Method for heat-sealing an inner container's sealed section to ensure it is liquid-tight.

Abstract

A method is provided for compressing and heat sealing a container closure "joint" at the edge of a polymer-coated medium or large cardboard panel folded 180° between the polymer-coated cardboard panel and the edge of a polymer-coated film element.

Description

Technical Field

[0004] , ,

[0001] The present invention is a method of compressing and heat-sealing an inner liquid container sealing "junction" that is liquid-tight, comprising a 180°-folded polymer-coated paperboard panel edge between a polymer-coated paperboard panel and an edge region of a polymer-coated film element.

Background Art

[0002] In mass production, compression tools generally remain in exactly the same precise position during long production cycles with large mechanical strokes. A 1 mm tolerance is required to press a polymer-coated paperboard sleeve onto an inner anvil without collapsing the wall of one or more polymer-coated paperboards. Thus, the polymer-coated paperboard sleeve needs to have a cross-section 2 mm larger than the inner anvil. Due to the required inner tolerance between the rectangular polymer-coated paperboard sleeve and the rectangular anvil, all container-sealing edges of the 180°-folded polymer-coated paperboard panel vary during mass production and do not reach the same position during compression and heat-sealing, damaging the edges of the 180°-folded polymer-coated paperboard panel or forming channels through which liquid penetrates outside the container, causing the container to leak during storage and distribution and damaging surrounding products.

[0003] The present invention is applicable to various polymer-coated paperboard container-sealing designs for liquids having medium or large paperboard grammages, in which the container-sealing inner section of a section of the 180°-folded polymer-coated paperboard panel edge is compressed and heat-sealed between the polymer-coated paperboard panel and the polymer film element edge.

[0004] When heat sealing using Ultra Sonic welding, in order to precisely control the energy direction for heat sealing the container seal in specific welding zones and to allow the container seal to be fully opened afterward, an inner heating alloy anvil with a 0.0045MT-110 50 textured etched surface pattern and a welding horn with a knurled pentahedron / square pyramidal micropattern are required in different heat sealing zones. In addition, one of the semi-hexagonal textured etched surface sections, raised 0.013-0.030” from the anvil surface, may have a serrated edge on one side. The points of the multiple pentahedrons need to be machined into the planar forehead, which is typically used to prevent multiple sharp points from penetrating the polymer layer. The angle between the pentahedron panels may be 60°. Incorporating a spring-loaded compression tool into the ultrasonic horn introduces several other technical problems, such as: because the actuated supersonic horn vibrates at high frequencies, any moving elements incorporated into the ultrasonic horn interfere with the frequency, making the ultrasonic welding process unstable.

[0005] According to the present invention, the front portion of the compression and heat-seal punch, on which the hard ball is formed, overlaps the joint of the pre-sealed container from the outer polymer-coated cardboard panel wall side with the front portion of the compression and heat-seal punch, which is embedded in a flexible elastomer body. Between the outer side of the inner panel of the polymer-coated cardboard and the edge region of the polymer-coated film element relative to the heated anvil, the polymer-coated cardboard edge, which is pre-folded 180°, is sealed by bending it laterally with an inelastic punch in the driving direction, without destroying the liquid-tightness of the 180° folded polymer-coated cardboard edge. It may be necessary to vibrate the front portion on which the ball is formed of the compression punch.

[0006] To prevent polyethylene (PE) from adhering to the heated alloy mandrel during the heat-seal compression process, the anvil must be coated with a non-stick polytetrafluoroethylene (PTFE) coating. When multiple stacked coated polymer-coated cardboard panels are compressed and heat-sealed ultrasonically, all layers are sealed together. To prevent some areas from being sealed together, allowing the container seal to be opened later, a non-heat-sealable water-based overprint varnish is applied to these surface areas during the flexographic printing process.

[0007] After heat sealing, some areas of the film element need to be peeled away from the polyethylene-coated cardboard panel when opening the container seal. Therefore, a peelable composite layer needs to be coated on the surface of the film element. A lacquer or polymer composite coating that is peelable and at the same time provides a heat seal with sufficient strength can be a complex application. To avoid this problem, according to the present invention, one side of a polyester (PE) film with a non-peelable low-density polyethylene (LDPE) coating is permanently heat-sealed to a non-peelable low-density polyethylene (LDPE) cardboard coating, and the other side of the polyester (PE) film is coated with a low-density polyethylene (LDPE) peelable composite layer, a portion of the film is folded, a lip is formed along the perforations, and both peelable low-density polyethylene (LDPE) peelable composite layers of the lip are heat-sealed together, peeled off only along the perforations, and after opening the carton closure, remains attached to the low-density polyethylene (LDPE) non-peelable layer of the cardboard.

[0008] By installing a half-depth cutting die within a rotary crimping and cutting manufacturing tool linked to a printing press that manufactures container blanks, deep polymer-coated cardboard sections can be delaminated and removed by vacuum before being folded 180° in the filling machine. The recess in the 180° folded polymer-coated cardboard edge minimizes the radius of the folded polymer-coated cardboard edge that is heat-sealed to the polymer-coated film element, eliminating any liquid pathways. [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] Therefore, the object of the present invention is to eliminate the aforementioned drawbacks and disadvantages associated with known sealing methods in the prior art.

[0010] Another object of the present invention is to provide a more economical container.

[0011] Another objective of the present invention is to eliminate the plastic screw caps required by consumers for all modern liquid cartons, and to introduce a paperboard biopolymer coating to provide a 100% biodegradable container, thereby protecting the environment in a more efficient way.

[0012] Another object of the present invention is to provide a container that reduces the consumption of natural resources. [Brief explanation of the drawing]

[0013] [Figure 1]A 180° folded polyethylene-coated cardboard panel is superimposed on the inner and inner film elements 2 of the outer polyethylene (PE)-coated cardboard, and a compression and heat-seal punch has a rigid front section into which a flexible ball is formed, and produces an inclined, guided imprint in the pre-folded and compressed seal, bypassing the edge of the 180° folded polyethylene (PE)-coated cardboard panel. Enlarged cross-section of the compression and heat-seal station. [Figure 2] Figure 1 shows an enlarged side cross-sectional view of the edge of a 180° folded polyethylene-coated cardboard panel, liquid-tightly sealed between the inner polyethylene-coated film element and the outer polyethylene-coated cardboard panel after compression and heat sealing. [Figure 3] Plan view of the inner portion of the container seal, showing an inner leak-proof joint where the polyethylene-coated film element edges overlap with the inner edges and inner surfaces of the 180° polyethylene-coated cardboard panel. [Figure 4] Enlarged isometric view showing the recessed edge of a polyethylene-coated cardboard panel folded 180°. [Figure 5] Enlarged side cross-section of a polyethylene (PE) coated cardboard panel heat-sealed to a film lip. [Figure 6] Enlarged side cross-section of a polyethylene (PE) coated cardboard panel, where a portion of the film lip is heat-sealed in a non-peelable manner, and the other side of the film lip is peelable from the film element, peeling and removing along the perforations of the film element when the seal is opened. [Figure 7] Plan view of an ultrasonic heat seal knurled pattern having oblique and vertically oriented sealing sections with a divided intermediate section, showing the sealed cross-sectional pattern of the sealed section of a cardboard container when folded flat. [Figure 8]Top view of the first panel of polymer-coated cardboard, where two perforated tabs are connected by two different perforation patterns and the two perforated tabs are heat-sealed to the second polymer-coated cardboard panel. [Figure 9] Isometric view of a mandrel assembly, which has a textured etched mandrel surface with two raised semi-hexagonal surface sections and a front part of the mandrel connected to the mandrel base by four hollow pins, preventing heat transfer from the heated upper plate to the mandrel base. [Figure 10] This is a side view of a four-mandrel index rotor with a left-side first mandrel having a rectangular container sleeve pressed onto the mandrel by an index timing belt, the seal being folded between the first and second mandrel stations, an ultrasonic welding stack at the upper second mandrel station heat-sealing the seal, the right-side third mandrel station compressing and sealing the seal liquid-tight according to the present invention, and the lower fourth mandrel station removing the rectangular cardboard structure containing the completed folded and sealed seal from the mandrel, an induction coil heating the upper mandrel plate as the mandrel plate passes under the induction coil between the fourth mandrel station and the first mandrel station. [Modes for carrying out the invention]

[0014] As shown in Figure 1, the channel 8 along the edge 7 of the 180° folded polymer-coated cardboard panel is formed in a conventional heat-seal station. The container sealing joint is compressed and heat-sealed liquid-tightly by the front portion of a compression and heat-seal punch with a hard ball formed on it against a heated mandrel 1. The front portion 6 of the compression and heat-seal punch with the hard ball formed on it is laterally movable within the flexible elastomer body 5 during compression, sealing the edge 7 of the 180° folded polymer-coated cardboard between the inner panel 3 of the outer polymer-coated cardboard and the edge region 2 of the polymer-coated film element, and compressing and heating the channel 8 liquid-tightly without damaging the polyethylene coating of the edge 7 of the 180° folded polyethylene-coated cardboard panel. Reference numeral 6 indicates an air or liquid passage within the hard punch, which cools the adhesion / adjacent flexible elastomer element 5 of the compression and heat-seal punch during long manufacturing cycles.

[0015] Figure 2 shows a liquid-tight joint 9 according to the present invention, after it has been compressed and heat-sealed to a liquid-tight state.

[0016] According to Figure 3, a top view of the portion shown in the drawing of Figure 2 is shown, in which the polymer-coated film element 10 is overlapped and heat-sealed on a 180° folded polymer-coated cardboard panel including a free edge 11 with a leak-proof joint 12, and is liquid-tight heat-sealed by a ball-formed front within a circle 13. Reference numeral 14 indicates the potential liquid pathway liquid-tightly sealed by the ball-formed front within the circle 13 after compression and heat sealing.

[0017] Figure 4 shows a concave edge 16 of a polyethylene-coated cardboard panel edge that is folded 180°, which has the potential to reduce and eliminate the liquid path inlet 15.

[0018] According to FIG. 5, a polymer-coated cardboard panel having a film lip 17 with a perforation along a fold line is shown, and the non-peelable side of the outer lip of the film element is permanently heat-sealed to the polymer-coated cardboard panel.

[0019] According to FIG. 6, a polymer-coated cardboard panel permanently heat-sealed to a film lip is shown, the polymer-coated cardboard panel includes a film lip, and in region 18, it is peeled from the film and only the film lip is peeled off at the perforation 19.

[0020] According to FIG. 7, vertically 20 and obliquely 21 oriented knurled seal patterns attached to a horn concave panel 22 are shown.

[0021] According to FIG. 8, polymer-coated cardboard tabs 25 and 26 connected by perforations at the edges of a polymer-coated cardboard panel 23 are shown. The polymer-coated cardboard tabs 25 and 26 are further heat-sealed to the polymer-coated cardboard panel 23. When tab 26 has a joining perforation length exceeding approximately half of the total length of the tab, the first perforation cut starts from the cardboard edge, and the entire tab 25 is separated when lifted by the unsealed cardboard panel 23. When tab 26 has a joining perforation length less than approximately half of the total length of the tab, the first perforation cut does not start from the cardboard edge, and the peeling is performed while one cardboard tab 26 layer remains connected to the polymer-coated cardboard panel 23 and the other cardboard tab 25 layer remains connected to the polymer-coated cardboard panel 24 along the perforation, enabling the panel 26 to be peeled off, providing a touchless opening of the seal.

[0022] As shown in Figure 9, four hollow alloy pins 28 are shown to prevent heat transfer from the heated (200°C) mandrel upper plate 27 to the mandrel base 29. When the temperature of the mandrel upper plate 29 drops to a predetermined level, a wireless infrared sensor signals to a temperature controller, activating an induction coil. As the mandrel upper plate 27 passes under the induction coil, the ferromagnetic material within the mandrel upper plate 27 is heated, maintaining the mandrel upper plate 27 at a constant temperature of ±100°C. Alternatively, a hot air blower or infrared heating element can be switched on and off, directed towards the mandrel upper plate 27. A third option is a 100-150 watt heating element integrated into the mandrel upper plate 27, controlled by an infrared wireless sensor with an image recognition camera that reads individual images of each mandrel, recognizes the temperature of each mandrel upper plate, and signals to the mandrel upper plate temperature controller. Each of the four lanes has four rotating mandrels connected to an index shaft. Eighteen power lines are connected to 16 heating elements on the mandrel upper plate 27 and to the mandrel base 29 via hollow pins 28, and the shaft center, which has nine channel slip rings, is joined at each end of the index mandrel shaft.

[0023] According to Figure 10, a side view of the first mandrel 30 of a four-mandrel index rotor is shown, and a rectangular container sleeve is pressed onto the mandrel by index stainless steel front reinforced polymer paddles 31 welded onto an endless steel-reinforced polyurethane (PUR) timing belt 32. The seal is folded between the first leftward-facing mandrel 30 and the second upward-facing mandrel 41 by a rotating bevel gearbox 33, which has two folding arms 34 of different lengths on either side of the seal and pivots in different directions, and the seal is pre-folded as the gearbox rotates around a stationary central shaft 35 by two guides 36 of different profile levels, which fold the seal plane before it enters under the ultrasonic weld horn 37. The upper-oriented mandrel station seals the carton seal by an ultrasonic stack including the horn 37, a booster 38, and a converter 39, and is driven by a pneumatic actuator 40 oriented at the top center of the ultrasonic stack. The rightward-facing third mandrel station 42 includes an additional expansion and compression die, as shown in detail, which, in accordance with the present invention, liquid-tightly compresses and heat-seals the joint of the pre-sealed ultrasonic seal. At the downward-facing fourth mandrel station 43, the vacuum cup pulls the outer panel of the container initially by a very small distance, and using two arms, releases the inner container seal from the front of the mandrel, and further pushes the rectangular carton structure with the folded seal out of the mandrel into the downward-facing pocket belt. Between the lower fourth mandrel station 43 and the first leftward-facing mandrel station 30, an induction coil 44 embedded in a Teflon® (PTFE) body operates to maintain the upper plate of the mandrel at a constant temperature.

[0024] The present invention should not be considered limited to the specific embodiments described above, but rather should be understood to cover equivalent methods and processes in all embodiments, and many materials and structures to which the present invention may be applicable will be readily apparent to those skilled in the art based on the examination herein.

Claims

1. A method for compressing and heat-sealing the inner section of a sealed joint for a liquid container having a polymer-coated cardboard panel edge folded 180° between a polymer-coated cardboard panel and a polymer-coated film element edge region, The 180° folded polymer-coated cardboard panel edge and the inside of the polymer-coated cardboard panel overlap the edge region of the polymer-coated film element. The folded, compressed and pre-sealed container sealing joint is compressed and heat-sealed from the outside of the container by a punch having a front portion in which a hard ball is formed. A method for compressing and heat-sealing an inner section of a liquid container sealing joint, wherein the front portion on which the hard ball is formed is flexible and moves laterally by colliding with the outside of the polymer-coated cardboard panel that is not folded 180° during compression after imprinting the polymer-coated cardboard panel on the outside of the container, thereby liquid-tightly heat-sealing the 180° folded polymer-coated cardboard panel edge between the inner panel of the polymer-coated cardboard on the outside of the container and the polymer-coated film element edge, without damaging the polymer coating of the 180° folded cardboard panel edge.

2. A method for compressing and heat-sealing the inner section of a sealed joint for a liquid container according to Claim 1, characterized in that the sealed joint has perforations, and the perforations break when the sealed joint is opened.

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