MXPA98007761A - Composite closure, method for assembling, and method for closing a container with - Google Patents

Abstract

The present invention relates to a composite closure for a container before fitting, which comprises a tubular plastic band substantially of open ends (24, 24 '), formed internally with one or more thread or snap-in formations (44). ) to be coupled with a complementary formation or formations (20) on the container, for attaching the closure to the container, and a captive insert disc (72) at least substantially of plastic material, which is adjusted and retained in the band, to overlap and seal with the lip defining the mouth (14) of the container, the strap including an abutment element (66) by which, when the closure is fitted to the container, a marginal region (82) of the disc (72) ) which includes the free edge (76), can be deformed down around the rim of the container (14), characterized in that: a) the disk (72) has its free edge (76) received in an annular recess that faces inwards (62, 62 ' ) adjacent an inwardly extending flange formation (28), which forms an opening (70) at one end of the band, and b) the disc (72) is of a larger size radially in relation to the recess (62, 62 '), and by engaging the free edge (76) with the outer periphery of the recess, it stops in a dome condition that is convex to the exterior of the closure, and projects towards the opening (70) of the band (6

Description

COMPOSITE CLOSURE, METHOD TO ASSEMBLE, AND METHOD TO CLOSE A RECIPIENT WITH THE FIELD OF THE INVENTION This invention relates to composite closures for packaging containers, that is, closures having a sealing disc configured as an insert for overlapping and sealing with the lip defining the mouth of the container, and a tubular plastic band of ends open where the disc is adjusted and retained. The invention also extends to the insert discs for these closures. The band of this closure is formed internally with one or more thread or instantaneous coupling formations that can be coupled with a complementary formation or formations on the container to join the closure and the container together.

BACKGROUND OF THE INVENTION For some packaging applications, composite closures have different advantages over conventional closures (ie, those having crowns without openings), and are widely used for food products that are hot filled or pasteurized or sterilized. In the container. A form of composite closure is known from the European Patent Specification Number 0272431B1 (reference of Agents: 4386), wherein the insert disc is cut and stamped from an extruded plastic material in multiple layers, to have a circular inner portion rounded by an external generally C-shaped portion. When the closure has been adjusted to a container, the outer portion of the insert disc forms an annular channel that faces downwards, by which the container flange is received in the container. a sealing relationship, and then the internal portion overlaps and closes the mouth of the container. A drawback of the closure disclosed in European Patent Number EP.0272431, and mentioned above, is presented due to the presence of the generally C-shaped external portion of the insert disc. To enable the disc to achieve satisfactory seal security with the container, heat and pressure are used in order to give the disc a required form of close tolerance around its margin. The present invention arises when the Applicants realized that substantial cost savings and other benefits can be achieved through the use of a flat sheet, at least substantially plastic, multi-layered or otherwise, that it can adopt (and adopt) a non-planar configuration required in the fitted closure. Another composite closure having a plastic or substantially plastic insert disc is shown in United States Patent Number 4782968. The disc can be cut from a flat sheet of plastic, with the added cost advantages. on discs having a non-planar configuration, by using an appropriate manufacturing method, for example, by thermoforming. However, in U.S. Patent No. US 4782968, the closure assembly requires that the disc be peripherally secured to the tubular closure band. The assurance operation, which is achieved by centrifugal welding, induction sealing, or mechanical rivet, is an additional manufacturing cost. Moreover, the union of the disc to the band will restrict the capacity of the disc to conform to the finish of the container with which it is required to seal, and may limit the applications for which the closure can be used, due to the need to avoid stresses. excessive in the interconnection made between the two components. It is also known that for conventional plastic closures, a disc-type sealing liner is provided, of a size such that, when the closure is fitted on the neck of a container, it projects outwardly beyond the rim of the container, as a hanging peripheral margin, and that the closure has a formation around the underside of its crown, and configured to be supported downwardly on the hanging margin when the closure is adjusted, such as by a stop to wrap the margin around the outer radius of the container rim. In this way, the seal security provided by the coating is improved, and becomes less sensitive to the top load of the closure in storage, in transit, and on display. A closure of this kind is provided in European Patent Publication Number EP 0693434A. OBJECTIVES AND ADVANTAGES OF THE INVENTION From the foregoing, it could be expected in accordance with the same, that the combination of an insert disk inherently -flat with a closure cover having a butt formation configured to be coupled with a peripheral margin The outer disk to wrap it in close sealing relationship around the container finish could provide a composite seal with a desirable combination of relatively low cost and good sealing integrity. However, a total or substantially plastic composition for the insert disc and the band, together with any elevated temperatures and / or differential pressures to which the closure can be subjected during use, and when additionally combined with an increased capacity of the closure to deform due to the weakening effect of the opening in the band above the insert disc, in practice, make it difficult to reliably achieve the achievement of good sealing integrity. Failures in the integrity of the seal can originate when the disc is being assembled with the band in the initial creation of the closure, and / or can be caused by the forces imposed on the band and the disc during a capping operation. to adjust the closure subsequently on a container. Whatever their origin, the Applicants have found that sealing failures can be substantially reduced if the assembled disc closures are subjected to radially inward compression forces, and, moreover, the dome formation of the discs resulting from them. forces are directed away from the closure, i.e. towards the adjacent opening in the band, which is available to accommodate the dome form at least partially. According to the invention, from a first aspect, there is provided according to the same, a composite closure for a container before adjusting it, which comprises a tubular plastic band substantially of open ends, formed internally with one or more formations of threaded or instantaneous coupling, for coupling with a complementary formation or formations on the container, for attaching the closure to the container, and a captive insert disc at least substantially of a plastic material, which is adjusted and retained on the band, to overlap and seal with the flange defining the mouth of the container, the band including a butt element by which, when the closure has been adjusted in the container, a marginal region of the disc including the free edge, can be deformed down around the rim of the container, characterized in that: a) the disk has its free edge received in an annular recess that faces towards a ro, adjacent to an inwardly extending flange formation, which forms an opening at one end of the band; and b) the disc is of a larger size radially in relation to the recess, and by engaging the free edge with the outer periphery of the recess, it stops in a dome condition that is convex to the exterior of the closure, and projects towards the opening of the band. According to a second aspect, the invention provides a method for assembling the band and the disc in the manufacture of the composite closure defined in the previous paragraph, characterized in that the disc is forced to a position inside the recess, passing through the threaded formation or of instantaneous coupling, by coupling a thrust element with a central region of the disc, thereby making the disc adopt the condition convexly in dome which is subsequently maintained by engagement with the outer periphery of the recess.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will become clearer from the following description of its modalities, which will now be described by way of example, and with reference to the accompanying drawings. In the drawings: Figure 1 shows a first closure embodying the invention when fitted to a container. Figure 2 shows the first closure / container combination, as seen on radial section II-II of Figure 1. Figure 3 is a fragmented view of the first closure / container combination, in a slightly modified form, but which illustrates the behavior of the combination in response to negative pressures inside the container. Figure 4 illustrates the assembly of the closure disc, with the closure band in the formation of the first closure. Figure 5 illustrates the manner in which the closure disk can be cut from a source sheet, and can be assembled into the closure band by a heated perforation assembly. Figure 6 is a view similar to Figure 2, and showing a second closure / container combination according to the invention, as seen on a radial section.

DETAILED DESCRIPTION OF THE INVENTION Referring now to Figures 1 and 2, a container 10 molded from a PET thermoplastic material (polyethylene terephthalate) has a reduced diameter neck 12 terminating in a flange 14 (Figure 2) , which defines and surrounds the mouth of the container (not referenced). The flange has a generally flat top face 15, and an outer radius 90. The neck is generally cylindrical. At some distance from the flange 14, it is formed externally with an annular transfer ring 16, by means of which the container can be carried for filling operations, and so on. Between the transfer ring and the flange, it is additionally formed with an annular snap-engagement projection 18, and a continuous-turn screw thread (CT) 20, of which a part can be seen in Figure 2.

A composite screw closure 22 fits over the neck of the container, to form a seal with the flange 14. The closure is formed of two components that are formed separately and assembled together after their formation. One of the two components is a tubular plastic band with open ends or cover 24, which is injection molded from polypropylene. As can be understood from Figure 2, it has a generally cylindrical central portion 26, and at the respective ends of the central portion, a flange portion of parallel faces extending radially inwardly 28, having a free inner edge 70, and an enlarged diameter portion 32. The central and flange portions 26, 28 are joined by an arcuate transition portion 30 that forms the upper corner of the closure, as shown. The enlarged diameter portion 32 is formed with a weakening line 34, to form a removable ring 40 at the lower end of the closure. A projection 42 formed around the interior of this ring, may be coupled below the instant coupling projection 18 of the container, to separate the closure ring in a manner to give evidence of known forcing, when the closure is removed. The central portion 26 of the plastic strip is formed internally with a continuous screw thread 44, which the screw thread coupling can make, with the screw thread 20 of the container, as shown. In addition, between the screw thread and the flange portion 28, and in the separation thereof, an annular retaining projection 46 is formed, which extends continuously around the closure, its ridge remaining approximately the same radius as the crests of the screw thread 44. The exterior of the central portion is formed with the ribs projecting 48, to assist in the fastening by the user. Now the attention is directed to the transition portion 30 of band 24, and to the nature of their respective junctions with the central and flange portions 26, 28. The outer surface 50 of the transition portion is partially circular in cross section, extending over an subtended angle of 90 °. It arises at its ends towards the outer surface 52 of the flange portion, and the external base surface 54 of the central portion, from which the ribs 48 project. The outer surface 52 of the flange portion is flat, while the outer surface 52 of the flange portion is flat. surface 54 of the central portion is cylindrical. The internal (non-referenced) surface of the transition portion 30 is specially configured for a purpose that will become clear. At its lower end it emerges with the upper flank 58 of the annular protrusion 46, in axial alignment with the internal base surface 60 of the central portion 26. From its junction with the protrusion 46, a partially circular location follows an undercut angle of about 90 °, as the outer periphery 56 of an inward recess 62, which extends around the band 24, the flank 58 forming its lower side face. Above the outer periphery 56 of the recess 62, the inner surface of the transition portion 30 is truncated, and thins up and in at an angle of approximately 45 ° to the axis of the closure XX. This trunco-conical portion 64 forms the upper side face of the recess, and arises at its upper end with the lower (non-referenced) surface of the flange portion 28. Together with the periphery 56, it forms a surface protrusion 66 projecting downwardly and inwardly in a convex manner in recess 62, and towards the interior of the closure. Accordingly, it will be seen that the thickness of the base of the strip 24 is generally uniform over the central, transition, and flange portions 26, 30, and 28, the thread 44, the projection 46, and the protuberance 66, each being formed by a local thickening of the band wall. The second component of the composite closure 20 is a sealing and sealing disc 72, which forms an insert in the band 24. The disc is circular, and is cut from a plastic sheet created by the co-extrusion of multiple layers of material. plastic through a horizontal and rectilinear die hole (not shown). The disc is originally flat, but as described below, it is deformed to the upward dome configuration shown in Figure 2, when the disc is inserted into the band, and subsequently the closure is fitted over the container 10. Then the disc closes the circular opening (not referenced) defined by the free edge 70 of the band. The diameter of the disc 72 is greater than the largest diameter of the annular recess 62, which is presented at its outer periphery 56. As illustrated in Figure 4, the insertion of the disc in the band is achieved by a cushioned pusher member 74, which is coupled with the disk on a central part of its area, leaving a peripheral margin of the free disk. With the band suitably restrained against movement, the disc is forced upwards, passing through the screw thread 44 and the retaining projection 46 of the band, until its free edge 76 comes to rest in recess 62. In the movement passing through the thread 44 and the projection 46, the closing disc is forced to adopt an upward dome-shaped condition. The formation of the dome will occur primarily in the pendant margin of the disc outside the pusher member 74, which accordingly will deform downward relative to the general plane of the disc, as shown. It may be preferred to prevent any dome formation of the disc above the pusher member, and this may be achieved by means of a fastening member (not shown) that engages the disc above the pusher member, and is restrained in an elastic manner by an appropriate element. However, in general, the dome shape of the disc above the pusher member is considered desirable, and is therefore encouraged; in this regard, it should be remembered that the opening in the band 24 is available to accommodate any convexity of the disc inside the free edge 70 of the band. Because it has a larger size relative to the recess 62, the disc 72 is not free to flatten completely, when the closure has been assembled, and the pusher member 74 has been removed. Accordingly, the disc is maintained in its condition in dome form by the compression forces generally radially inward imposed on it by the band 24. The formation of residual dome in this sense is beneficial, because it ensures a correct deformation of the disc, when the closure is subsequently adjusted to a container, as described now. The closure disk after assembly to the band 24 is securely held captive within the recess 62 by the protrusion 66 and the projection 46 on each side, and by the interference of its free edge 76 with the outer periphery 56 of the recess. The location and orientation of the disc inside the band, therefore, remain within narrow limits of tolerance, with little or no risk of straightening or of a random deformation that could damage the safety of the seal of the closure after covering. In this condition, the closure is dispatched to the packer. Figure 5 shows the use of a drill assembly incorporating a heated perforator 74 'to form a disk 72, having a dome configuration, even before being inserted into the band 24. With the assistance of a cutting ring 78, the perforator is also used to cut the disc of the source sheet 80. The closure can be applied to a container filled with product 10 by conventional capper equipment, possibly (but not necessarily) at a time when the product is hot, and / or there is steam in the upper space above it. As the neck of the container 12 moves, in relative terms, up and into the closure, its flange 14 engages with the underside of the closure disc, and forces the disc upwardly against the flange portion 28.

A marginal region 82 of the closure disc, which includes its free edge 76, lies radially outside the rim of the container 14. Before the disc engawith the flange portion 28, this region, which is already subject to some deformation towards down by the closing assembly operation as described above, it engawith the protrusion 66 of the band 22, and subsequently deforms further down the protrusion, to the substantially inclined position shown in Figure 2. During this movement Further down the marginal region, the portion of the disc that overlies the mouth of the container may be subject to dome movement in the upward direction. Therefore, it can be considered that the protrusion is a stop element for the disc. Due to the substantial deformation created by the disk, the marginal region 82 of the disk moves in and down with a substantially truncoconical configuration, and the free edge of the disk 76, as shown, can lose contact with the web 22. Without However, the free edge still remains radially well outside the ridge of the ledge 46. The Applicants prefer that, at the end of the capping operation, the angle of the included cone of the generally truncoconical marginal region 82, is within the scale from 120 ° to 60 °, preferably approximately 90 °. As mentioned above, the closure disc 72 has a multilayer plastic structure. It can have two or more layers, one intermediate of which, for example, EVOH, can be provided to improve the gas barrier and / or moisture. Only one of its layers is specifically shown in Figure 2. It is the innermost layer 79 of the disc, and is formed of a polymer resin conforming to the relatively soft configuration, such as a soft grade of polypropylene. Figure 3 further shows that the disk has a thin central barrier layer 84, and a thick top layer 86, which imparts substantial mechanical strength to the disk. Suitable materials for layers 84, 86 are well known to the skilled person. During capping, when relative upward movement of the marginal region 82 of the closing disc 72 is prevented by the protrusion 66, the marginal region becomes wrapped down around the outer radius 80 of the rim of the container 14, such so that the soft bottom layer 79 of the disc in that location is brought into intimate contact with the container finish, and forms a seal with the container. Due to the axially directed component of its orientation, the seal made by the disc at radius 80 is less susceptible to variations in top loading, than would be a seal formed exclusively with the generally flat top surface of the flange of container 14. More yet, during capping, the transition and flange portions 30, 28 of the fastener strip 24 are subject to an elastic deformation in the outward direction, with the result that a substantial elastic pressure generally normal to the fastener is maintained. marginal region 82 of disk 72 through the web after the capping is finished. In accordance with the foregoing, and also by virtue of the soft nature and conformation of the layer 79, the seal formed between the disc and the container is airtight and secure until the first opening by the user, despite the imperfections that may occur. exist in the container's finish. Also, and as illustrated in Figure 3, the downward inclination of the marginal region 82 makes it possible for the closure disc to better resist inward (ie, downward) dome formation caused by high levels of partial vacuum in. of the container, which can be generated by products that are hot filled and / or closed with steam flow. Removal of closure 22 by the user is achieved in the normal manner, unscrewing the band in the appropriate direction. As mentioned above, if the free edge 76 of the disc has lost contact with the band in its inward and downward movement when the closure was applied, the band can initially rotate and rise through a small initial movement before it is released. alter the disc. With additional movement of the band, the free edge of the disc engages with the upper flank of the retaining projection 46, the seal made between the disc and the container is broken, and the disc rotates and rises with the strip to be removed. . Due to this two-stage process, the maximum torque that the user must exert to remove the closure is reduced in a substantial way. This is of a particular value if there is a high partial vacuum in the upper space of the container, and / or a substantial addition caused by residues of the product that are present in the interface of the disc / container. On the other hand, if the degree of dome formation resulting from the closing assembly operation is sufficient, the free edge 76 of the disc 72 can remain in a compression engagement in the recess of the band 62 throughout the operation of covered. This configuration may be preferred for the applications of the invention where high torques for removal are unlikely to be encountered. Whether or not the free edge of the disk maintains contact with the web during capping, the downward tilt of its marginal region 82 resulting from the deformation that occurs during assembly and capping, as described above, improves capacity. of the disc to withstand the forces of removal of the closure without inversion, thus reducing any risk of the band separating from the disc and leaving it behind on the container. An additional contribution for a satisfactory disc removal is provided by any cold setting of the plastic material of the disc until its deformed state that is present in the closure adjusted in the time elapsed before its removal. The cold setting prevents any substantial relaxation of the disk towards its original flat condition for the limited time in which the web is unscrewed. Figure 4 - shows a second embodiment of the invention, which is identical to the modality described above, except for the transition portion of the plastic band. The modified transition portion, and the band of which it is a part, are denoted according to the above, by the references 30 'and 24'. Instead of combining to form a protrusion 66 as in Figure 2, the trunco-conical abutting surface 64 'of the transition portion 30' of this second embodiment arises smoothly with the generally partially circular external periphery 56 'of the internal recess 62 ' Accordingly, although the transition portion, therefore, again provides an abutment by which the marginal portion 82 abuts and deforms, the degree of deformation that results is a little less than the deformation caused by the protrusion. in the first mode, and therefore, the closure may be more suitable for use with products for which only a liquid seal is required. The invention can be applied to closure / container combinations having multi-start threads, instead of the continuous-turn screw threads of the embodiments shown. In a modification of the described configurations, the screw threads 20, 44 of the container and the closure are of multiple starts, and the lower faces of the recesses 62, 62 'are discontinuous, and are formed by the upper ends of the segments of the screw thread of the respective lock 44. The projections 46 are omitted in accordance with the same. Although the closures of the described modalities have closure discs made entirely of plastic materialIt is contemplated that, in some applications of the invention, a thin metal layer or layers may be included. In one of these configurations, the outer surface of the closure disk is formed for cosmetic purposes by a thin metal covering, deposited in a vacuum.

The invention is not limited in its application to screw closures as is particularly described, but also has application in snap-fit fasteners. In addition, although it is preferred and desirable that the entire closure disc be initially flat to be assembled to the closure band as described above, within the scope of the invention are the closure configurations and the methods for forming them where the disc closure is not initially flat. For example, the part of the disc destined to overlap in the mouth of the container, can be formed with ribs for reinforcement purposes, and / or can be recessed in a truncated surface step capable of locating the disc centrally in relation to the container, coupling in of the container flange.

Claims (14)

NOVELTY OF THE INVENTION Having described the above invention, it is considered as a novelty, and therefore, the content of the following is claimed as property: CLAIMS

1. A composite closure for a container before fitting, which comprises a tubular plastic band substantially of open ends (24, 24 '), formed internally with one or more thread or snap-in formations (44) for coupling with a formation or complementary formations (20) on the container, for attaching the closure to the container, and a captive insert disc (72) at least substantially of plastic material, which is adjusted and retained in the band, to be overlaid and sealed with the flange defining the mouth (14) of the container, the band including an abutment element (66) by which, when the closure has been adjusted to the container, a marginal region (82) of the disc (72) that includes the free edge (76), can be deformed down around the rim of the container (14), characterized in that: a) the disc (72) has its free edge (76) received in an annular recess that faces inwards (62, 62 ') adjacent to a formation a flange extending inwardly (28), which forms an opening (70) at one end of the band; and b) the disc (72) is of a larger size radially in relation to the recess (62, 62 '), and by engaging the free edge (76) with the outer periphery of the recess, it stops in a condition of dome that is convex to the outside of the closure, and projects towards the opening (70) of the band (66).

2. A closure according to claim 1, characterized in that, by virtue of its dome formation, the disc (72) projects towards the opening (70) in the flange formation (28). A closure according to claim 1 or claim 2, characterized in that the disc (72) is inherently flat, but stops in its dome-like condition by its engagement with the outer periphery of the recess ( 62, 62 '). A closure according to claim 1, characterized in that the disc (72) has a multilayer structure, which has its innermost layer of the closure formed of a soft plastic material. 5. A closure according to claim 1, characterized in that the recess (62, 62 ') is formed between the flange formation (28), and a retaining projection extending inwardly (46). formed around the band (24, 24 '), adjacent to the thread formation or instantaneous coupling (44) thereof. 6. A closure according to claim as claimed in any of the preceding claims, characterized in that the butt element (66) is convex inside the closure. 7. A closure according to claim 1 in any of claims 1 to 5, characterized in that the butt element (66) is truncated. A method for assembling the band (24, 24 ') and the disc (72) in the manufacture of the composite closure claimed in any of the preceding claims, characterized in that the disc (72) is forced to its position inside the recess ( 62, 62 '), through the formation of thread or instantaneous coupling (44), by means of the coupling of a pushing element (74, 74'), with a central region of the disc, thus making the disc ( 72) adopt the condition convexly in dome, which is subsequently maintained by its coupling with the outer periphery of the recess. 9. A composite closure according to claim 1 in any of claims 1 to 7, when fitted on a container, characterized in that, by virtue of its engagement with the abutment element (66), the marginal region (82) of the disc (72) is deformed to a generally truncoconical position extending downward. 10. A combination of compliance with that claimed in claim 9, characterized in that the marginal region (82) of the disc (72) is tilted downwards, by an angle within the range of 30 ° to 60 °. 11. A combination according to claim 10, characterized in that the marginal region (82) of the disc (72) is tilted downward by an angle of approximately 45 °. 12. A combination according to claim as claimed in any of claims 9 to 11, characterized in that the free edge (76) of the disc (72) has been separated from the base of the recess (62, 62 ') by the deformation caused by the butt element (66). 1

3. A combination of conformance to that claimed in any of claims 9 to 11, characterized in that the free edge (76) of the disc (72) remains in engagement with the base of the recess (62, 62 '). 1

4. A combination according to claim 13, characterized in that the closure is a screw closure.