MXPA98004366A - Method of and apparatus for treating a laminate - Google Patents

Abstract

A groove (16) is provided through a covering (12, 13) forming part of a laminate (11) and extending over a polymer layer (15) of the laminate (11). By way of the groove (16), a limited zone (15A) of the polymer layer (15) substantially aligned with the groove (16) is heated to a temperature such that, following cooling of the zone (15A), the zone is more readily breakable. The covering (12, 13) mitigates the effect of the heat H on other zones of the polymer layer (15).

Description

METHOD AND APPARATUS FOR THE TREATMENT OF A LAMINAR UNIT DESCRIPTIVE MEMORY This invention relates to a method and apparatus for treating a limited area of a polymer layer of a laminar unit. Document EU-A-4Z65616 mentions that it was known that the orientation of a oriented thermoplastic polymer film can be destroyed by heating the film to a temperature above the temperature at which the film was oriented. Describes a continuous procedure for forming a longitudinally weakened strip in a cross-overlapping oriented poly-thin film. The method comprises directing heat from two longitudinally aligned sources to opposite sides of a strip of the cross-lapped, oriented polyolefin film, to such an extent that the tensile breaking strength in the heat-weakening strip formed in this way is on the scale of 20 to 100 N. per cm. of film length. The film formed in this way is to pack explosives in suspension form. Containers comprising a laminar unit consisting of a substrate having one or more layers of polymer towards the inside thereof are well known. It is known that the laminar unit consists of the following layers that go from the outside to the inside of the container: an outer polymer layer (for example LDPE-pol and low-density poly), a substrate (for example cardboard), a layer of barrier polymer (for example EVOH-ethylene vinyl alcohol) and an inner polymer layer (for example LDPE) which makes contact with the contents, for example a fruit juice or long-life milk. It is particularly advantageous to keep the barrier polymer layer intact from the manufacturing time of the laminar unit to the opening of the container by the consumer. It is also known that the container is designed in such a way that the opening of the container requires the rupture of the barrier polymer layer by the consumer, for example when cutting the consumer through the barrier layer or pushing in a portion of the container. of the barrier layer. To facilitate the opening of a pouring hole (in case, for example, the container has a spigot sealed by a lid sealed to the outside of it), or a hole for a straw, the potential hole can be delineated by a closed or open loop slot formed through at least a portion of the outer polymer layer and the substrate to limit a portion of the laminar unit that will be pushed inward. The groove can be formed by laser engraving, die cutting or milling, for example. It is also known to provide a similar arrangement to facilitate tearing a portion of the container to open it. In some circumstances. despite the formation of the slot »the barrier polymer layer and the inner polymer layer can provide a higher breaking strength than that desired to open the container by the consumer. Document EU-A-5000321 discloses a package for containing consumer articles that is made from a multilayer composite sheet material. The package includes at least one transversely extending seam seal and an aperture arrangement positioned adjacent to the seam seal. The aperture arrangement includes an aperture section comprising weakened sections in the form of a line in which the material of the composite sheet is weakened in terms of its resistance to rupture. These weak sections can be slots, so that the synthetic layers that are on an aluminum layer are thinner than anywhere else on the composite packing sheet. This can be achieved, for example, by heating it with a laser beam. A change in the breaking strength of a section in the form of a line can not only be achieved by macroscopic changes (grooves), but also by means of changes in the structure of the internal material, for example by means of changes in the degree of polymerization of the material. In accordance with an aspect of the present invention. A method is provided comprising providing a laminar unit comprising a polymer layer and a cover extending over a surface of said polymer layer, the outer surface of the cover being provided with a hole therethrough, characterized because it transmits energy by means of said hole to a limited area of said polymer layer substantially aligned with said hole to heat said limited zone to a temperature such that after cooling of the limited zone, said limited zone can be broken more easily. In accordance with another aspect of the present invention. an apparatus is provided comprising supply means for providing a laminar unit consisting of a polymer layer and a cover extending over a surface of said polymer layer »said outer surface of the cover being provided with a hole through it. the same, characterized by means of energy transmission arranged to transmit energy by means of said hole to a limited area of said polymer layer substantially aligned with said hole to heat said limited area to a temperature such that. after the cooling of said limited area »said limited zone can be broken more easily. Thanks to the present invention, it is possible to relatively precisely limit that area or those areas of the polymer layer whose breaking strength is really reduced, since the cover serves as a mask that mitigates any effect, on other areas of the polymer layer, the energy produced by the heating of the limited area (s). As a result, it is not necessary to use a very precise and expensive heating apparatus, for example a laser apparatus, and a less precise and cheaper apparatus can be used, for example hot air emitters. Suns believe, although they are not sure in any way, that the reason why the heating in question weakens the polymer in a way that makes it more breakable is that the relatively high molecular orientation that originates through Processes such as extrusion coating for the formation of the polymer layer, provides a relatively high resistance to rupture but that the application of heat to the layer reduces the degree of molecular orientation in the layer and therefore reduces the resistance to the break. In this way, it would appear that the heating should be such that there would be a significant reduction in the degree of molecular orientation in the polymer layer. The present invention is particularly »but not exclusively» applied to a packaging laminar unit »especially to a laminar unit forming a packaging container where the limited area of the polymer layer is required to be broken by the consumer to open the container. Additional or alternatively to the consumer obtaining access to the contents through a spout that surrounds the limited area. He could obtain access through a straw used to break the limited area and / or tearing a portion of the container to throughout zone 1 imitated. When the packaging laminar unit consists of a substrate with a barrier layer towards the inside thereof, if the barrier layer is a metal foil, for example an aluminum foil, the polymer layer (see p. -polyethylene, PE copolymers "or ionomers) that will become more breakable will be towards the inside of the metal sheet" probably in contact with the contents of the package. In case the barrier layer is a polymer layer (e.g. »of EVOH» PA-polyamide, PET-polyethylene terephthalate or PEN-polyethylene naphthalate). so the barrier layer and any polymer layer (s) inwardly thereof are advantageously made easier to break. The heating should at least be to soften the limited area of the polymer layer along at least a major part of its thickness and preferably sufficient to melt that area over at least a major part of its thickness . The heating time at the softening point or melting point of the polymer layer should be between O.ls. and 5s. »preferably between 0.5s. and 2s. The heating can be carried out by hot air, radiantly, ultrasonically or inductively. To achieve a dedicated heat for a sufficient time, the heating is preferably carried out in a machine in which a laminar unit belt is converted into full containers. As an alternative, in a system where pieces are cut from a laminated tape and supplied to a forming machine. filler, sealer, the heating is preferably carried out after that machine. In this last system, it may be possible to carry out the heating in a plant in which the tape is converted into the pieces. The polymer layer that will be made more breakable can be provided by extrusion, co-extrusion or lamination. The hole can have several shapes seen perpendicular to the laminar unit; for example, it can be a curved and / or linear groove and can be formed by laser engraving, die cutting or milling, for example. In order that the invention may be clearly understood and carried out easily, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a block diagram representing a packaging machine in which A filled cardboard is produced directly from a tape of packaging material. Figure 2 is a fragmentary and developed view of a laminated wall of a tube formed from the tape. Figure 3 is a perspective view of a filled and sealed carton produced in the machine of Figure 1. Figure 4 is a block diagram representing a converter of an alternative version of the system, in which the converter converts a tape in cardboard covers? FIG. 5 is a plan view of a piece of cardboard cut from the tape in the converter of FIG. 4, FIG. 6 is a fragmentary section taken on line VI-VI of FIG. 5, FIG. Figure 7 is a diagrammatic perspective view of a filled and sealed carton produced using the piece of Figure 5, Figure B is a block diagram representing a packaging machine of a modified version of the last system, in which full rectangular cartons and sealed are formed from cardboard sleeves, Figure 9 shows a diagrammatic vertical section through a full and sealed triangular top board, produced in the machine of Figure 8 »and after having been opened by the consumer Figure 10 shows a section taken on the line XX of figure 9. but at the beginning of the opening by the consumer, and figure 11 shows an alternative version of the detail shown in the figure. 2. With reference to Figure 1, a packaging machine 1 receives a ribbon 11 which is printed with an artistic pattern by a printing device 2 »and then a hole-forming device 3» for example a rotary milling head, makes a hole in the tape in the form of a 1S slot. The tape 11 is then formed in a vertical tube which is sealed by heat and pressure along overlapping edges thereof, and portions 15A of a polymer layer 15 are heated substantially at the same time. The apparatus for forming and sealing the tube and for heating the portions 15A is indicated with the number 4. The tube advances downwards and, by means of a filling device 5. a liquid product therein which will be packed is continuously filled to a substantially constant level in the tube. Then a sealing device 6 seals the tube advancing down transversely at intervals along it, trapping the liquid product between the seals and the transverse seals are cut centrally from their widths by a cutting device 7 to produce full tetrahedral cartons and sealed "each substantially identical to the cardboard 8 shown in Figure 3. The laminated structure of the tape 11 supplied to the packaging machine 1 can have any suitable character, for example the character shown in Figure 2» 6 or 9. In reference to figure 2 »the laminated tape 11 consists of an outer polymer layer 12» a cardboard layer 13 and an inner polymer layer 15. which will make contact with the liquid contents of the cardboard 8 ("outer" and "inner") "are words that refer to the positions of the layers in question in the carton 8 produced). The groove ÍS is formed through the layers 12 and 13 towards the outer surface of the layer 15 »which has the form of an open or closed loop and limits a portion 17 of the layers 12 and 13 which will be pressed to the inside by a consumer to break the layer 15 around the base of the slot lß to allow the portion 17 to be pushed into the container to allow the contents to be sucked out through the soda hole formed in this manner. As indicated by the arrows H. heat in the form of hot air emitted at a temperature of approximately S00 ° C. but which naturally comes to the belt 11 at a lower temperature, it is applied to the belt in the region of the portion 17 for about 1.3s .. and a part of the heat penetrates the base of the groove 16 (1 mm wide) ) along the length of the slot. By thus exposing the measured area 15A of the polymer layer 15 at the base of the groove 16 to an intense heat for a short period of time, an internal structural change occurs in the layer 15 in that area 15A and remains after the enfliation. Although the heating of zone 15A has utility with a laminar unit of the character shown in FIG. 2, it has a greater utility with a laminar unit of the character shown in FIG. 11 where a barrier layer 14, especially a layer that it constitutes a suitable barrier for oxygen, it is interposed between the cardboard layer 13 and the inner polymer layer 15. whereby the pushing of the portion 17 inwards is more difficult. The barrier layer 14 can consist of a metal foil »for example an aluminum foil» or it can be a polymer layer (e.g. »of EVOH, PA, PET or PEN); and illustrated in Figure 11 as a polymer layer. In the version of FIG. 11, the heat supplied is preferably such that both the limited area 14A of the layer 14 at the base of the groove 16 and the cleaned area 15A undergo internal structural changes that remain after cooling. In a test on a triangular top character board having an outer polymer layer 12 consisting of LDPE of 14 microns thick, a cardboard layer 13 of 400 microns thick »an aluminum layer 14 of B micrometers. thickness having outer and inner layers of 15 microns and 6 microns thick respectively, but not illustrated, and an inner polymer layer 15 consisting of LDPE 50 microns thick »was discovered that the force required to be applied to the portion 17 to break layers 14 and 15 was approximately 80N. After heating as indicated, the required force was approximately 40N. In the converter 20 illustrated in FIG. 4 and in the alternate version of the system, a laminated tape 11 is printed with an artistic pattern by a printing device 21 and slots 6T are formed in the tape 11 by a hole forming device 22. which is preferably one or more lasers. Then, the tape 11 has pieces 23 each as shown in Figure 5 cut from it by a device 24. The pieces 23 are advanced forward in the direction of a heating apparatus 25 where respective edges of the pieces 23 are heated to make them sticky. Then, the pieces 23 are bent to create flat cardboard covers by means of a folding device 26 »and the sticky edges form side seams of the covers. The covers are advanced towards a heating apparatus 19 where the limited areas 15AT are heated to the required temperature. Since the period of time required for heating is relatively long, the speed of movement of the sleeves through the apparatus 19 is much less than the speed of movement of the belt 11 and of the pieces 23 through the converter 20. In reference to figure 5, each piece 23 is formed with a set of marked lines 27 to provide a row of lower closing sealing panels 2B »a row of lower closing sealing panels 29. a row of sidewall panels 30, a row of top closing shutter panels 31 and a row of top closing sealing panels 32. The groove 16 'is mainly linear and extends along the boundary between the row of top closing shutter panels 31 and the row of top closure seal panels 32. However, the slot 16 'has its end portions 16A' extending to the free edge 33 of the row of top closure sealing panels 32. The unit laminates r 11 'of the piece 23 can have any suitable character, for example the character shown in figure 6, which corresponds to that shown in figure 9, except that the barrier layer 14 is a metal sheet, particularly an aluminum sheet . As indicated by the arrows Hf in FIG. 6, the heat in the form of radiant heat emitted at a temperature of approximately 600 ° C, but which naturally arrives at the part 23 at a lower temperature, is applied to the piece in the region of the slot 16 'for approximately 1.3s and a portion of the heat penetrates to the base of the slot 16 »(which measures 1mm wide) along the extension of the slot. By thus exposing the limited area 15A 'of the polymer layer 15 at the base of the groove 16' to intense heat for a short period of time by conduction through the aluminum layer 14, an internal structural change occurs in the layer 15 in that area and it remains after cooling. After the piece 23 has been bent to create a flat sleeve and sewn from the sides, it is transported to a forming machine, filler and senator in which the flat cover is opened to a rectangular shape, the cover is placed on a mandrel of a turret »a sealed bottom seal is formed while the cover is on the mandrel, the open upper part formed of this way is removed from the mandrel and advanced to be filled and sealed at the top to provide a flat top board 34 of the character illustrated in Figure 7, in which the ends of the fin seal provided by the sealing panels of top closure 32 are glued on the respective side wall panels 30. To open the cardboard »the consumer simply peels off from the side wall 30 the end of the flap seal through which the slot 16t extends and flips it upwards, and then. starting at the inner end 16A 'of the bent slot 16 * »tears that length of the sealing flap l mited by the groove, the polymer layer 15 and thus the layer of aluminum foil 14, tearing along the I mited area 15A '. In the system described with reference to figures 4 to 7, the formation of the slots 16 'and the heating of the zones 15Af is carried out on the converter. In the modified version of which the packaging machine 35 is shown in Figure B »said slots are not formed» and said limited zones are not heated on the converter, but instead the formation of the slots (in any way and size) and the heating of the limited areas is carried out after the packing machine 35. On that machine, the sleeves sewn on the sides are opened by an opening device 36. Afterwards. as indicated by the number 37 »the covers are placed on mandrels of a turret. Although the shells are on the mandrels, the sealed lower closures are formed thereon, the slots, for example the loop-shaped slots 16 are formed, for example mechanically on the outer surfaces of the sheaths, and the limited areas 15A are heated to the necessary temperature; all by the apparatus indicated with the number 38. The cartons are then removed from the mandrels, as indicated by the number 39, and advanced to a filling device 40 and then to a device 41 that forms top seals sealed in the cartons , after which a pour spout attachment applicator 42 secures pour spout accessories 43 to the cartons 51. Referring to Figures 9 and 10. the triangular top board 51 has top closure roof panels 52. and 53 and a top closing sealing flap 54. Liquid contents 55. for example milk or orange juice, from the container 51 almost fill the container, leaving an upper space 56 limited by the roof panels 52 and 53. The container 51 consists of a laminar unit 11 comprising the following layers progressing outwards: an inner thermoplastic layer 15. for example low density polyethylene (LDPE). which constitutes a barrier for the liquid contents 55. a layer 14, for example an aluminum foil or ethanol-vinyl alcohol (EVOH), which constitutes a barrier for a gaseous substance, for example oxygen, a hardening layer 13, for example of cardboard, and an outer thermoplastic layer 12, for example of LDPE, which constitutes a water barrier. In panel 52 there is a laser cut through the outer thermoplastic layer and the hardening layer, but not through the gaseous barrier layer or the inner thermoplastic layer, and thus in the form of a partial deep cut. , a circular but open loop 16"'groove extending thereby on the outer surface of the panel 52. Sealing by heat and pressure to the outer thermoplastic layer around the groove 16' 'is a directed annular flange Outwardly 58 of a ring 59. The ring 59 includes an externally threaded intermediate annular portion 60 and an annular upper inwardly directed flange 61. The annulus 59 coaxially surrounds a tubular spout 62 and is connected thereto by thin bridging portions and frangible 63. The ring 59 and the spout 62 are injection molded in one piece from pol et leno The lower edge 64 of the tubular spout 62 is formed as a knife edge a diameter almost as big as that of the renura 16". It has a cylindrical internal sealing surface 65 and an external and convex annular sealing surface 66. In the condition in which the container is received by a consumer, there is a closure cap 67 screwed on the ring 59 having a radially rim external 6B which is internally threaded at number 69 for its cooperation with part 60. Cover 67 also has an internal edge hanging downwards 70 »whose radially outer surface is cylindrical to cooperate sealable with surface 65. Spout 62 is Having formed an outer and annular shoulder 75 for leaning against the flange 61. Having received the card 51 and for opening the pouring fitting 43 »the consumer unscrews first and removes the lid 67. Afterwards, the consumer uses his finger or thumb to push the spout 62 inward to break the bridging portions 63. A result of the inward movement of the spout 62 is that the surface 66 slides sealable It is placed inside the surface 63 and advanced through the surface 63 to remain in a fixed position shown in Figure 9, in which the shoulder 75 abuts the flange 61. Another result of the inward thrust of the spout 62 is that the portion 17 of the panel 52 bounded by the slot 16 't is pressed inward thereby breaking the gaseous barrier layer 14 and the inner thermoplastic layer 15 in the zones 14AT "and 15A", so that the portion 17 make hinge around the bridging portion 77 between the portion 17 and the rest of the panel 52. The accessory 43 and the portion 17 are now in a condition ready for pouring »after which the cardboard 51 is tilted in the direction of the arrow A in figure 9. Sracias to the location of the open portion 17 on the upper side instead of the lower one, from the spout 62 »the liquid 55 that is poured tends to push the portion 17 beyond the inlet to the spout 62 instead of pushing it towards that inlet. When it is desired to re-close the pouring fitting 43 for further pouring later, the lid 67 is screwed back onto the ring 69 and its edge 70 is easily adapted to the surface 65. The formation of the holes, such as slots 16, 16 'and 16", and the heating of the limited areas, such as 15A, 15A' and 15A", do not have to be carried out in the particular system steps described with reference to the drawings, but rather they can be carried out at different stages in the systems. It will be understood that the particular varieties of the system described above with reference to the drawings are not limited to the production of the particular containers illustrated for the respective varieties, but that each can be used to produce containers of a different character. Likewise, it will be appreciated that the present invention is applicable to a wide variety of systems for producing filled and sealed containers.

Claims (9)

NOVELTY OF THE INVENTION tQVXNPICCIQ EN

1. - A method comprising providing a laminar unit (11) consisting of a polymer layer (15; 14; 15) and a cover (12; 13) extending over a surface of said polymer layer (15; 14; 15), the outer surface of the cover (12, 13) being provided with a hole (16; 16 '; 16") through it» characterized in that energy is transmitted by means of said hole (16; 16'). 16") to a limited area (15A; 14A. 15A; 15A '; 14A", 15A ") of said polymer layer (15; 14; 15) substantially aligned with said hole (16; 16'; 16") for heating said limited zone (15A; 14A, 15A; 15A '»14A", 15A ") to a temperature such that» after cooling of the limited area (15A; 14A, 15A; 15A »; 14A', 15A") , said limited zone (15A; 14A, 15A; 15A; 15A; 14A ", 15A") can be broken more easily.

2. A method according to claim 1, further characterized in that said heating is selected from the group consisting of heating by hot air, radiant heating, ultrasonic heating and inductive heating.

3. A method according to claim 1 or 2, further characterized in that said heating and cooling do not substantially alter the shape of said limited area (15A; 14A5 15A; 15A'f 14A ", 15A").

4. A method according to any preceding claim, further characterized in that said cover (12, 13) includes an oxygen barrier layer (14) and said hole (16, 16 '; 16") extends from said outer surface of said cover (12, 13) to substantially the surface of said barrier layer (14) closer to said cover (12, 13).

5. A method according to claim 4, further characterized in that said barrier layer (14) comprises a metal sheet through which the energy supplied by means of said hole (16 ') is conducted to said limited area ( 15A

6. - A method according to any of claims 1 to 3, further characterized in that said polymer layer (15) comprises an oxygen barrier layer

7. A method according to any of the preceding claims, further characterized in that the period of said heating, at least the softening point of said polymer layer (15; 14 »15), is between O.ls and 5s B. - A method according to claim 7 Also characterized because The period is between 0.5s and 2.s. 9. A method according to any of the preceding claims "and carried out in a packaging machine (1)» in which said laminar unit (11). starting in the form of a belt (11), it is converted into packing containers (8) substantially simultaneously with the filling of product therein. 10. A method according to any of claims B »and carried out in a packaging machine (35) to which said laminar unit (11) is supplied in the form of a piece of packaging container (23) and wherein said piece (23) is formed in an open container that is then filled and closed. 11. A method according to any of claims 1 to B and carried out in a converter (20). wherein said laminar unit (11), starting in the form of a belt (11). It is converted into pieces of packaging container. 12. A method according to any of claims 9 to 11 »further characterized in that after said cooling and after the production of a full and closed packing container (8), another area (17) of said polymer layer (15) around which said limited area (15A; 15A ") extends, is displaced to provide an opening 13. A method according to any of claims 9 to 11, further characterized in that after said cooling and after the production of a full and closed packing container (34), said packing container (34) is torn open along said limited area (15A ') 14.- A method of compliance with any of the preceding claims, further characterized in that said hole (16; 16 '; 16") has been provided through said external surface by removing material from said cover (12; 13). 15. An apparatus comprising a supply means for providing a laminar unit (11) consisting of a polymer layer (15; 14, 15) and a cover (12, 13) that extends over a surface of said polymer layer (15, 14 »15), the outer surface of the cover (12, 13) being provided with a hole (16, 16 '; 16") therethrough, further characterized by energy transmission means (4; 19; 38) arranged to transmit energy by means of said hole (16, 16 '; 16") to a limited area (15A; 14A, 15A; 15A'; 14A"; 15A ") of said polymer layer (15; 14: 15) substantially aligned with said hole (16, 16 *; 16") to heat said limited area (15A; 14A, 15A; 15A '; 14A"; 15A ") to a temperature such that after of the cooling of said limited zone (15A; 14A; 15A; 15A '; 14A ", 15A"), said limited zone (15A; 14A, 15A; 15A'; 14A ", 15A") can be broken more easily. - An apparatus according to claim n 15, further characterized in that said power transmission means (4; 19; 3B) are selected from the group consisting of hot air emission means, radiant heating means; ultrasonic heating means and inductive heating means. 17. An apparatus in accordance with the claim 15 or 16, further comprising hole forming means (3, 22, 38) for forming said hole (16, 16 '»16") through said cover (12, 13) by removing material from said cover (12, 13). 1

8. An apparatus according to any of claims 15 to 17, and in the form of a packaging machine (1), further comprising means (4, 6, 7) for converting said laminar unit (11), initiating in the form of a belt (11), in packing containers (8), and filling means (5) to fill them substantially simultaneously with said conversion. 1

9. An apparatus according to any of claims 15 to 17, and in the form of a packaging machine (35) further comprising means (36, 37, 38) for converting said laminar unit (11), starting in of a piece of packaging container, in an open packaging container, filling means (40) for filling said container and closing means (41) for closing said container. 20. An apparatus according to any of claims 15 to 17, and in the form of a converter (20), in which said laminar unit (11), starting in the form of a belt (11), is converted into pieces of packaging container (23).