US20180141692A1

US20180141692A1 - Lid assembly for a packing container, packing container with such a lid assembly, and method for manufacturing same

Info

Publication number: US20180141692A1
Application number: US15/574,997
Authority: US
Inventors: Peter Hauck; Eugen Gerber; Joachim Zimmermann; Holger Kocksch
Original assignee: Sonoco Development Inc
Current assignee: Sonoco Development Inc
Priority date: 2015-05-19
Filing date: 2015-05-19
Publication date: 2018-05-24
Also published as: EP3297932A1; CA2986176C; CA2986176A1; ES2740905T3; EP3297932B1; WO2016184478A1

Abstract

A lid assembly, for a packing container, includes a lid ring of a plasticizable, thermoplastic polymer material and a dimensionally stable lid part, to be placed on the lid ring. The lid part (or the lid ring) has a layer of a peelable plastic material, on a side facing the lid ring (or the lid part), that contains a sealable, thermoplastic polymer or is coated with a cover layer of such a polymer. The lid ring (or the lid part) has an end face facing the lid part (or the lid ring), with two parallel circumferential projections, arranged at a distance of at most 3 mm and sealed to the peelable layer or to the cover layer of the lid part (or of the lid ring). A packing container with such a lid assembly as well as a method for manufacturing same by ultrasonic welding are also provided.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Phase Application of International Application PCT/EP2015/001016 filed May 19, 2015, the entire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention pertains to a lid assembly for a packing container, with a lid ring consisting of a plasticizable, thermoplastic polymer material and with a dimensionally stable lid part that can be placed on the lid ring, wherein—the lid part has at least one layer of a peelable plastic material on its side facing the lid ring, wherein the peelable layer contains at least one sealable, thermoplastic polymer and/or is coated with a cover layer consisting of such a polymer, and wherein the lid ring has, on its end face facing the lid part, at least one circumferential projection, which is sealed to the peelable layer and/or with the cover layer of the lid part; or—the lid ring has, on its side facing the lid part, at least one layer of a peelable plastic material, wherein the peelable layer contains at least one sealable, thermoplastic polymer and/or is coated with a cover layer consisting of such a polymer, and wherein the lid part has, on its end face facing the lid ring, at least one circumferential projection, which is sealed to the peelable layer and/or with the cover layer of the lid part.

BACKGROUND OF THE INVENTION

The present invention further pertains to a packing container with a sleeve, which sleeve is provided with such a lid assembly, as well as to a method for manufacturing such a lid assembly.
Packing containers, which are provided with lid assemblies, which comprise a lid ring that can be placed on a lid part, are widely used especially in the form of so-called composite cans. The lid part in this case closes one end of the sleeve usually manufactured from paper or cardboard composite materials, to which sleeve the lid ring is fixed, while the other end of the sleeve is closed by a bottom part. Such packing containers or cans are used especially for accommodating free-flowing or fluid substances, for example, foods and luxury foods. To protect the contents of the packing container from external effects, e.g., moisture, or from loss of substance, for example, due to drying out, the material of the sleeve usually has an inner lamination consisting of an essentially gas- and liquid-impermeable material, such as aluminum, plastic or the like.
In addition to such a protection of the packaged goods, the packing containers may, as a rule, be sealed by means of a membrane consisting of a gas-impermeable material, such as metal, plastic or the like, in order to guarantee in this manner an extensive protection and longer shelf life of the packaged goods as well as protection of the consumer against unintended or intentional damage or contamination of the packaged goods. If the packing container is provided with such a lid assembly of the above-mentioned type, the membrane is sealed onto the sealable inner lamination along a cylindrical sealing surface on the inner side of the sleeve, or is sealed onto the end face of the sleeve if this has an opening edge, for example, in the form of a crimp, which can be closed with a simple snap-on lid. Such a membrane sealing is permanently removed more or less completely at the time of the first opening of the cardboard composite can, as a result of which an opening of the cardboard composite can, once performed, is clearly recognizable. To ensure simple tearing off of such a membrane, without rests of the membrane, which have sharp edges and consequently represent a risk of injury, being left behind on the inner circumference of the sleeve and projecting into the interior of the sleeve, so-called peelable membranes are frequently used, which consist of a plurality of layers having a lamellar configuration, at least one layer of which is manufactured from a peelable, delaminating material. Such membranes are known, for example, from EP 2 386 410 A1.
The lid assembly is used in prior-art packing containers mainly to reclose the packing container after the sealing membrane, if present, has been removed, wherein the lid part should advantageously be in as close a contact as possible with the lid ring fixed on the top side of the sleeve in order to protect the packaged goods, insofar as possible, against external effects. Moreover, it is known that the lid part can, in turn, be sealed or welded onto the lid ring, so that, on the one hand, a tamper-evident closure is formed, which is capable of showing the first-time opening of the packing container and which can offer, on the other hand, an additional or alternative protection for the packaged goods against external effects, in addition to the membrane, providing that the lid ring is also connected to the sleeve in a gas- and liquid-tight manner, due to it being sealed or welded, for example, to the inner lamination of the sleeve.
The latter is, however, problematic in case of a more or less dimensionally stable lid part, as it is necessary for having the ability to fix it on the lid ring after the first-time opening, e.g., in a positive-locking or non-positive manner, such as in a clamping or locking manner or in some other manner. There is a problem in this connection because when the lid part is sealed or welded onto the lid ring, a more or less flat fused connection is generated, which makes it very difficult to separate the lid part from the lid ring in a simple manner at the time of the first-time opening, and, moreover, both the lid part and the lid ring may be damaged in the process.
AT 366 639 B describes a packing container consisting of a thermoplastic plastic, which passes over on a top side into a ring-shaped flange in the manner of a lid ring. To make it possible to weld or seal a lid part on this “lid ring” as permanently, gas-tightly and nondetachably as possible, for example, by means of ultrasound, the upper sealing surface of the “lid ring” facing the lid part has one or more weld combs, which project upward from this “lid ring” and which lead to a locally intense heating of the polymer material during the welding operation in order to permanently connect the lid part to the flange-like “lid ring” in a gas-tight and nondetachable manner. For the first-time opening, i.e., for the first-time separation of the lid part from the “lid ring,” the latter is provided with a peripheral predetermined breaking line close to its sleeve section, so that the terminal ring section permanently welded to the lid part or practically the entire “lid ring” together with the lid part can be detached from the sleeve section of the container. The drawback is, on the one hand, the relatively laborious breaking up of the “lid ring” from the sleeve along the predetermined breaking line when the lid part welded thereto shall be removed for the first time, and, on the other hand, only a ring section that is parallel to the sleeve is available as a sealing surface at the inner circumference, which is in contact with a projection of the lid part, which projection meshes with the sleeve, after the first-time opening, so that the sealing effect of the lid part leaves something to be desired, after it has been separated from the sleeve for the first time.
Moreover, the applicant noted that sealing or welding of the lid part on the lid ring also causes problems when the lid ring is provided with a layer of peelable plastic material, which shall ensure a clean separation of the lid ring. The reason for this is mainly that the sealing or welding of the dimensionally stable lid part on the lid ring requires such a large amount of melting energy due to its greater material thickness compared to that of conventional membrane films that the peelable layer is destroyed and it is no longer able to fulfill its intended function of providing good opening behavior. This is especially true in case of an ultrasonic sealing or welding, in which the lid part is set to vibrate by means of ultrasound in order to heat its contact surface with the lid ring as a consequence of friction and to seal or weld them to one another. It was found in this connection that depending on the dimensions of the lid, such a large amount of ultrasound energy is necessary to generate a satisfactory, liquid- and gas-tight connection that peelable layers of the lid part are destroyed. The two functions, namely, to ensure a simple separation of the lid ring from the lid part, on the one hand, and to guarantee a gas-tight connection between same, on the other hand, are thus in conflict with one another, because great tightness requires melting of the lid ring with the lid part possibly over the full surface (high ultrasound energy and/or high contact pressure), while the slightest possible melting is necessary to spare the peelable layer, which must not be destroyed during the ultrasonic welding or ultrasonic sealing (low ultrasound energy and/or low contact pressure).
WO 2013/167958 A1 describes a packing container with a lid assembly of this class, which comprises a lid ring placed on the sleeve of the container and a lid part that can be placed on said lid ring. Both the lid ring and the lid part are manufactured from dimensionally stable plastic materials. As far as the connection of the lid ring to the lid part is concerned, provisions may be made for the latter to be provided with a layer of a peelable plastic, the peelable layer containing a sealable thermoplastic polymer, such as polyethylene. The lid ring consists, e.g., of polypropylene and comprises a horizontal section, onto which the lid part is sealed or welded. The connection surface of the lid ring intended for the welding/sealing to the lid part may be configured with a circumferential projection, which shall act as an energy flow indicator during the welding by means of ultrasound.
The ultrasonic sealing of the lid ring with the lid part to establish a gas-tight connection between same, on the one hand, and to prevent the peelable layer from being destroyed, on the other hand, to the extent that a reliable separation of the lid part from the lid ring cannot be ensured any longer, is problematic here as well. Even though the circumferential projection acting as an energy flow indicator ensures a linear contact of the lid with the lid ring during the ultrasonic welding and consequently a linear sealing, a slight melting at best takes place radially inside and outside of this weld line due to lack of contact. This further implies, albeit, of course, in a slightly understated form, the above drawback, namely, that a reliable fused connection cannot be achieved in a reproducible manner, because it extends only along a very narrow circumferential line parallel to the course of the circumferential projection, as long as the peelable layer of the lid is prevented from not being destroyed. Moreover, such (excessively) “thin” melt lines form during the first-time removal of the lid from the ring, so-called “angel hair,” which is defined as fine, hair-like plastic filaments, which ensure the fused connection and are completely separated during the tearing open on account of their extremely small thickness and may fall into the container, which is not desirable in view of a contamination of the packaged goods.

SUMMARY OF THE INVENTION

A basic object of the present invention is therefore to perfect a lid assembly of the above-mentioned type as well as a packing container provided with such a lid assembly in a simple and cost-effective manner such that the lid part can be sealed or welded onto the lid ring in an essentially gas-tight and liquid-tight manner, but a simple first-time separation of the lid part from the lid ring is nevertheless ensured. The present invention is further directed towards a method for manufacturing such a lid assembly.
This object is accomplished according to the present invention in a lid assembly of the above-described type by-the lid ring having, on its face facing the lid part, at least two circumferential projections, which are arranged essentially parallel and which are sealed to the peelable layer and/or with the cover layer of the lid part; or-the lid part having, on its end face facing the lid ring, at least two circumferential projections, which are arranged essentially parallel and which are sealed to the peelable layer and/or with the cover layer of the lid ring, wherein the distance between the circumferential projections is at most 3 mm.
A packing container suitable for accomplishing this object is characterized in that the packing container has such a lid assembly, with a lid ring that is fixed at one end of the sleeve, especially in an essentially gas- and liquid-tight manner.
Finally, the present invention makes provisions, from a technological point of view, for accomplishing this object in a method for manufacturing such a lid assembly, for the lid part to be placed onto the lid ring and for the lid part to be energized with ultrasound, wherein the peelable layer is energized with ultrasound, wherein the peelable layer and/or the cover layer of the lid part or of the lid ring are sealed with ultrasound while forming a fused connection between the circumferential projections.
The configuration according to the present invention makes it possible in a surprisingly simple manner to seal or weld the dimensionally stable lid part provided with at least one peelable layer (or the lid ring provided with the at least one peelable layer) of the lid assembly onto the lid ring (or onto the lid part) by means of ultrasound and thus to form both a tamper-evident closure that can be opened in a very simple and convenient manner and to ensure the greatest possible gas and liquid tightness of the lid assembly, because the at least two circumferential projections, which extend approximately parallel and are arranged at a very short distance of at most 3 mm, ensure that not only a linear, narrow fused connection, which is guaranteed only by “angel hair,” becomes established at each of the projections, but a flat fused connection will be formed in the area between the circumferential projections, especially as a consequence of heat conduction from both (or even more than two) circumferential projections, and this fused connection does not lead, due to the absence of contact between the circumferential projections during the ultrasonic energization, to a thermomechanical compromise of the peelable layer. The at least two circumferential projections prevent plasticized plastic material from flowing off during the ultrasonic welding, so that this remains in the intermediate space between the circumferential projections in the manner of a ring-shaped “lake” in order to ensure the greatest possible gas tightness of the fused connection and at the same time to make possible a reliable tearing off of the lid part from the lid ring, because the peelable layer is capable of satisfactorily fulfilling its function of ensuring good separation behavior there due to the absence of damage (see below with reference to FIG. 6). If desired, the lid assembly according to the present invention is capable of eliminating the need for an (additional) sealing member in the interior of the sleeve of the packing container, even though such a sealing membrane may, of course, basically nevertheless be provided.
The circumferential projections of the lid ring (or of the lid part), which are in contact with the lid part (or with the lid ring), do not consequently act only as local energy flow indicators during the ultrasonic sealing or ultrasonic welding of the lid part to the lid ring by being locally plasticized or fused as a consequence of friction with the lid part prestressed especially mechanically in the direction of the lid ring when the lid part is set into ultrasonic vibrations at the time of the ultrasonic welding operation by means of a sonotrode, but the projections also considerably simplify the procedure, because the ultrasonic welding parameters, especially ultrasonic energy and contact pressure, can be set in a broad range compared to the state of the art, namely, from very low values (until the intermediate space between the circumferential projections has just become filled with polymer material having melted from them, in order to ensure the high tightness) up to relatively high values (up to a slight thermomechanical damage to the peelable layer directly at the tips of the projections, which still “just” guarantee a simple separation). The ultrasonic energy necessary for the formation of this welded or sealed connection (or the amplitude of the ultrasound) can consequently be selected, despite the relatively great thickness of the dimensionally stable lid part compared to a membrane film, to be low enough to prevent a thermal and/or mechanical destruction of the peelable layer of the lid part, so that this layer is capable of fulfilling its intended function without problems in terms of ensuring good opening behavior. The method according to the present invention is especially practically self-regulating, because even if a local thermomechanical compromise of the peelable layer occurs in the immediate contact area of the circumferential projections of the lid ring (or of the lid part) with the lid part (or with the lid ring), which may even be desirable concerning a high and reliable gas tightness, a fused connection is produced in the areas located between the circumferential projections essentially only as a consequence of heat conduction, so that destruction of the peelable layer is ruled out there at any rate. Consequently, not only is an especially secure, reliable and reproducible fused connection having the greatest possible tightness formed between the lid ring and the lid part, but a defined area, within which the peelable layer of the lid part (or of the lid ring) is capable of being torn off from one another at the time of the first-time separation, is formed especially in the area, e.g., an approximately ring-shaped area, between the circumferential projections, in which area a fused connection is likewise formed as a consequence of heat conduction during the ultrasonic sealing or ultrasonic welding. The lid ring may be placed before the welding operation on the sleeve of the packing container, so that the lid part remains freely accessible to be set into ultrasonic vibrations.
The material of the peelable layer may have, in principle, any desired known structure, and its ability to be delaminated is usually achieved by it being formed from at least two polymers, which have poor compatibility with one another and/or have different melting points, as a consequence only relatively weak binding forces act at the boundary surfaces of the material, so that it can be cleanly separated. Peelable layers consisting of polyolefins, on the one hand, such as polyethylene, e.g., LDPE (low-density polyethylene), polypropylene or copolymers thereof and polymer blends and other polyolefins, such as polypropylene, polyethylene, polybutene, e.g., isotactic polybutylene-1 (iPB-1), or copolymers and polymer blends thereof, shall be mentioned only as examples in this connection. The lid part provided with such a peelable layer (or the lid ring provided with such a peelable layer) may especially have a laminate-like structure itself and comprise, in addition to the peelable layer, additional layers, such as dimensionally stable support layers, e.g., likewise made of polyolefins, terephthalates, e.g., polyethylene terephthalate, polyamides and the like, bonding layers, barrier layers (see farther below in this connection), etc. Further, the peelable layer may form the immediate cover layer on the side of the lid part facing the lid ring (or on the side of the lid ring facing the lid part), and at least one of the polymers of the peelable layer is ultrasonically sealed or ultrasonically welded to the lid ring (or to the lid part) (i.e., the peelable layer is used itself to form the fused connection), or the peelable layer may is coated on the outer side with a sealable or weldable thermoplastic cover layer, which ensures at least predominantly the formation of the sealed or welded connection and remains on the lid ring (or on the lid part) at the time of the first-time separation of the lid part from the lid ring, while the peelable layer arranged under it is torn.
It should be noted here that the term “sealing” refers within the framework of this disclosure to the establishment of a fused connection, and the term “welding” is used synonymously.
It may further be advantageous during the ultrasonic welding or ultrasonic sealing of the lid part to the lid ring if the lid part is energized with ultrasound by means of at least one sonotrode, which extends at least essentially around the entire circumference of the at least two circumferential projections of the lid ring, so that a fused connection of the lid ring to the lid part is ensured over the entire surface at least in the area between the circumferential projections. The sonotrode may be, for example, plate-shaped or ring-shaped.
The at least two circumferential projections of the lid ring or of the lid part may be arranged, for example, essentially concentrically, and, as was mentioned, the distance between them is at most 3 mm. Consequently, two (or even more) circumferential projections extend in such a case concentrically around the circumference of the lid ring or of the lid part, even though it is, of course, also possible to arrange the circumferential projections in another manner, for example, in a more or less sinusoidal or zigzag course around the circumference of the lid ring or of the lid part, insofar as the distance between two parallel circumferential projections is always at most 3 mm. For example, a grid-like, diamond-shaped, honeycomb-shaped arrangement, etc., of circumferential projections arranged in pairs each around the circumference of the lid ring or of the lid part is likewise conceivable, the distance between the circumferential projections arranged in pairs being again at most 3 mm.
While it is often sufficient for ensuring a satisfactory gas tightness of the welded or sealed connection between the lid ring and the lid part to provide exactly two circumferential projections on the end faces thereof, a greater number of such circumferential projections may, of course, be provided as well. The possibility of three circumferential projections at a distance of at most 3 mm or of four circumferential projections, two each of which or even all four of which have a distance of at most 3 mm, shall only be mentioned as an example here.
The radial distance of the circumferential projections is preferably between about 0.3 mm and about 3 mm, especially between about 0.5 mm and about 2 mm, and preferably between about 0.7 mm and about 1 mm.
Moreover, it proved to be advantageous if the circumferential projections have a height between about 0.05 mm and about 0.4 mm, especially between about 0.1 mm and about 0.35 mm, and preferably between about 0.15 mm and about 0.3 mm, and they preferably should have a height of at least about 0.05 mm in order to prevent them from melting off more or less entirely, which would lead to a flat transmission of the ultrasonic energy and as a result of this to a flat thermomechanical stress on the entire end face of the lid ring and of the lid part being in contact herewith, which stress would in turn lead to the risk of destruction of the peelable layer at least after a certain stress duration.
It further proved to be advantageous if the cross section of the circumferential projections tapers towards the free end of the projection, with the projection tapering to a tip especially upward (or toward its free end). Even though such circumferential projections tapering to a tip impart a relatively high stress due to pressure locally on the peelable layer immediately at the beginning of the ultrasonic welding operation, a tip-shaped configuration of the circumferential projections is nevertheless seen to be favorable, because the melting off of the tip of the circumferential projections a consequence of very rapid local heating of the circumferential projections leads to a spontaneous melting off of the tips to fill the intermediate space between the circumferential projections with the plasticized material having melted off and to form hereby the gas-tight, but yet easy-to-open fused connection.
The circumferential projections may have especially an essentially triangular cross section, which preferably tapers to a tip upwardly for the above-mentioned reasons, but may basically also have a rounding on the end face.
As was mentioned already, the lid part has, at any rate, a sufficient thickness to ensure its desired dimensional stability, which enables it to be placed again onto the lid ring and to be fastened to it after the first-time separation from the lid ring, be it brought about by clamping, locking or in another manner. In an advantageous embodiment, the lid part has a thickness totaling at least about 0.2 mm, especially totaling at least about 0.3 mm and preferably totaling at least about 0.4 mm, and it may preferably have a thickness of up to about 10 mm, especially up to about 8 mm, preferably up to about 5 mm, and especially preferably less than 5 mm.
As was already suggested above, provisions may, moreover, be made in another advantageous embodiment for at least the lid part to have at least one additional layer in the form of an essentially gas-tight and liquid-tight barrier layer in order to ensure the hermetic sealing of the packaged goods and thus to make a sealing membrane in the interior of the packing container dispensable. Such barrier layers are known as such and may be formed, for example, from metal or metal oxides, e.g., silicon (di)oxide, aluminum, aluminum oxide, etc.; from polymers, e.g., ethylene vinyl alcohol (EVOH), polyvinyl alcohol (PVOH), polyvinylidene chloride (PVDC), polyamide (PA), including copolymers and polymer blends thereof, etc. Such barrier layers may be laminated, for example, as an outside cover layer or-optionally with the intermediate arrangement of suitable bonding layers-as an inner layer at the time of the process of manufacturing a suitable laminate used for the cover part or applied in the form of a coating.
As was likewise already suggested, provisions are made in an advantageous embodiment of the lid assembly according to the present invention for the lid part to have at least one circumferential projection, which projects in the direction of the lid ring, and whose cross section is adapted to the cross section of a contact surface of the lid ring, which contact surface is complementary to it, such that the lid part can be fixed to the lid ring after the first-time separation from the lid ring, the lid part especially being essentially sealingly in contact with the contact surface of the ling ring. The lid part, which may be configured, for example, as a deep-drawn part, may now have a circumferential projection, whose outer cross section essentially corresponds to the inner cross section of the lid ring, so that the circumferential projection of the lid part is in contact on (re)closing with the inner cross section of the lid ring along a ring-shaped contact surface. The outer cross section of the circumferential projection of the lid part and/or the inner cross section of the lid part may be coated, if desired, with a suitable sealing material.
The sleeve of a packing container according to the present invention, such as a can, which container or can is provided with a lid assembly of the above-described type, may advantageously have an essentially gas-tight and liquid-tight inner lamination, which may be manufactured from know materials suitable for this purpose, such as metals (e.g., aluminum) and/or polymers.
Provisions may be made in this case in an especially advantageous embodiment for the inner lamination of the sleeve to have at least one layer consisting of a sealable plastic material, which is sealed to the lid ring of the lid assembly, so that a permanent, satisfactorily gas-tight and liquid-tight sealed or welded connection is also ensured between the sleeve of the packing container and the lid ring of the lid assembly according to the present invention. The sealed or welded connection may be established in any desired and known manner, for example, likewise by means of ultrasonic sealing or ultrasonic welding, by means of high-frequency sealing or high-frequency welding or the like.
The method according to the present invention offers especially the possibility of first attaching the lid ring onto the sleeve of a packing container and of subsequently sealing or welding the lid part to the lid ring by means of ultrasound.
If the sleeve has at least one layer consisting of a sealable plastic material, the lid ring can be sealed or welded to the inner lamination of the sleeve in the above-described manner after it has been placed on the sleeve, which may happen especially along an inner circumferential section of the sleeve, with which sleeve the lid ring meshes.
Further features and advantages of the present invention appear from the following description of an exemplary embodiment with reference to the drawings. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a schematic perspective view of a packing container in the form of a can with an embodiment of a lid assembly according to the present invention, with a lid ring that is fixed at one end of the sleeve, and showing the lid part removed;

FIG. 2 is a schematic sectional view of the packing container provided with the lid assembly according to FIG. 1;

FIG. 3 is a schematic detail view showing detail B according to FIG. 2;

FIG. 4 is a schematic perspective view of the lid ring of the lid assembly according to FIGS. 1 through 3 in the unfinished state, i.e., prior to the sealing or welding to the lid part;

FIG. 5 is a schematic detail a sectional view of the lid ring according to FIG. 4; and

FIG. 6 is a micrograph of an ultrasonic welded or sealed connection according to the present invention between the lid part and the lid ring of a packing container according to FIG. 1 in an area between the two circumferential projections of the lid ring, which circumferential projections are arranged at a distance of about less than 1 mm.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, the packing container schematically shown in FIGS. 1 and 2 and designated by reference number 1 as a whole is formed by a so-called composite can in this exemplary embodiment and has a sleeve 2, which is manufactured, for example, from a paper or cardboard composite and may be provided with an essentially gas-tight and liquid-tight inner lamination with an inner, sealable or weldable cover layer, e.g., one made of polymer-coated aluminum. The sleeve 2, which does not, of course, necessarily have to have the more or less square cross section shown but may also have any other desired cross-sectional shape, e.g., a round, oval, polygonal shape, etc., is closed on its underside in the conventional manner by means of a bottom part 3 (FIG. 2), which may be manufactured itself from corresponding materials just as the sleeve 2, but also of metal, plastic or corresponding composites with high gas-tightness and liquid-tightness.
A lid ring 4 of a lid assembly, designated as a whole by the reference number 5, which is manufactured from a thermoplastic polymer material, for example, one based on polyethylene, is fixed at the end of the sleeve, which end is the upper end in FIGS. 1 and 2 and faces away from the bottom part 3. As is seen especially in FIG. 3, the lid ring 4 has a more or less L-shaped cross section, whose first leg 4 a is arranged parallel to the sleeve around the upper inner circumferential section of the sleeve 2 and whose second leg 4 b extends essentially at angles hereto around the upper end of the sleeve 2 and extends over and covers the upper end face of the sleeve 2. The outer circumference of the first leg 4 a of the lid ring 2 is sealed or welded to the inner lamination of the sleeve 2, for example, by means of ultrasonic or high-frequency sealing or ultrasonic or high-frequency welding.
As can likewise be seen in FIGS. 1 and 2, the first leg 4 a of the lid ring 4 is further used to clampingly mount a dimensionally stable lid part 6 of the lid assembly 5, which lid part is configured, for example, in the form of a deep-drawn part, on its inner circumference, by its inner cross section approximately corresponding to the outer cross section of a circumferential projection 4 a projecting in the direction of the lid ring 4, so that the lid part 6 can be detachably fixed to the lid ring 4, and the outer cross section of its circumferential projection 4 a is sealingly in contact with the inner cross section of the first leg 4 a of the lid ring 4.
As can be seen in the detail views of the lid ring 4 according to FIG. 4 and especially according to FIG. 5, which show the lid ring 4 according to FIGS. 1 through 3 in the unfinished state, the lid ring 4 has, on its end face facing the lid part 6 (not shown again in FIG. 4 and FIG. 5), i.e., on the side of its second leg 4 b, which is the upper side in FIGS. 4 and 5, two parallel circumferential projections 4 a, 4 d, which are concentric in this case and project upward from its end face. The radial distance of the two circumferential projections 4 c, 4 d equals about 0.8 mm in the unfinished state, while its height, likewise in the unfinished state, equals about 0.2 mm. The overall thickness of the legs 4 a, 4 b of the lid ring 4 may equal, for example, about 1.4 mm in this case. The circumferential projections 4 c, 4 d taper in this case-likewise in the unfinished state shown in FIGS. 4 and 5—upward and taper upward, e.g., essentially to a point, so that they have an approximately triangular cross section.
The lid part 6 has a laminate-like structure, not shown in the drawings, with a plurality of layers, and it comprises, when viewed from its side facing the lid ring (4) in the direction of its side located opposite this lid ring (4), a peelable layer, e.g., one consisting of an LDPE/iPB-1 composite, a bonding layer, a barrier layer, e.g., one based on EVOH, another bonding layer and a carrier layer, e.g., one consisting of polyethylene terephthalate (PET). Moreover, an additional sealable layer, e.g., one based on polyethylene, may optionally be applied, for example, to the side facing the lid ring (4), i.e., to the peelable layer. For the purpose of a sufficient dimensional stability and stability, the lid part 6 having such a structure has, e.g., an overall thickness of about 0.5 mm.
To seal or weld the lid part 6 onto the lid ring 4 shown in FIGS. 4 and 5 in the unfinished state while forming a gas-tight and liquid-tight tamper-evident closure. the lid part 6 placed on the lid ring 4, which is especially already connected in advance to the sleeve 2 of the packing container 1 and is then energized by means of ultrasound, for example, at a frequency of about 10 kHz to about 50 kHz, e.g., 20 kHz, and over a duration of about 0.5 sec to about 5 sec, e.g., about 1 sec to 2 sec, and is set to vibrate, in order to seal or weld the peelable layer of the lid part 6-and/or optionally the sealable cover layer arranged on the outer side thereof—onto the upper end face of the second leg 4 b of the lid ring 4. This may be brought about especially by means of one or more sonotrodes (not shown), which are pressed from the top onto the lid part 6 and which advantageously extend essentially around the entire circumference of the circumferential projections 4 c, 4 d of the lid ring 4 (i.e., congruently with these), in order to ensure a satisfactory and uniform sound transmission.
As can be seen in FIG. 3, which shows the lid ring 4 in a state in which it has already been sealed or welded to the lid part 6 and the lid part 6 has again been separated (for the first time) from the lid ring 4 while tearing up its peelable layer, the circumferential projections 4 c, 4 d of the lid ring 6 are partly melted off at least in the area of their tip during the ultrasonic sealing or ultrasonic welding (their height is therefore smaller compared to FIG. 5), so that a gas-tight and liquid-tight fused connection is produced there as well as especially between the circumferential projections 4 c, 4 d and also in the areas located radially next to the circumferential projections 4 c, 4 d as a consequence of heat conduction, wherein even though a fused connection is likewise formed in the areas located radially next to the circumferential projections 4 c, 4 d and especially between same, where the lid part 6 had no or only a weak pressure contact with the lid ring 4 during the ultrasonic welding, the peelable layer is not destroyed based on a markedly lower thermomechanical load, so that it can fulfill its intended function of ensuring good opening behavior without restrictions.
If desired, it is, of course, also possible to provide more than two circumferential projections 4 c, 4 d at the lid ring 4, which do not necessarily have to extend concentrically with the lid ring 4. Further, it is possible to provide the lid part 6, instead of the lid ring 4, with two or more, corresponding circumferential projections and to provide the peelable layer in the upper end face area of the lid ring 4 (neither one being shown).
Finally, FIG. 6 shows a micrograph of an ultrasonic welded or sealed connection according to the present invention, where it can be seen that that a fused connection 4S, which was formed entirely from plastic material plasticized during the ultrasonic welding and melted off from the two circumferential projections 4 c, 4 d, and at which fused connection the peelable layer (see on the underside of the lid part 6 facing the lid ring) has nevertheless remained fully intact, became established between the circumferential projections 4 c, 4 d of the lid ring 4 b, which circumferential projections are arranged at a distance of about 0.8 mm in this case. The peelable layer has still remained partially intact even in the area of the-partly melted-off-tips of the two circumferential projections 4 c, 4 d, so that simple and secure (first-time) separation of the lid part 6 from the lid ring 4 is ensured in case of a tight fused connection, which extends over the entire radial section between the two circumferential projections 4 b, 4 c, and this fused connection ensures great tightness even in the absence of a partial tearing-off of the material of one of the parts 4, 6 and adhesion to the other parts 6, 4 when the lid part 6, once separated, is fixed again to the lid ring 4, i.e., in purely positive-locking or frictionally engaged manner.
While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

Claims

In the claims:

1. A lid assembly for a packing container, the lid assembly comprising:

a lid ring consisting of a plasticizable, thermoplastic polymer material; and

a dimensionally stable lid part, which can be placed on the lid ring, wherein:

the lid part has, on a side facing the lid ring, at least one layer of a peelable plastic material, wherein the layer of peelable plastic material contains at least one sealable, thermoplastic polymer and/or is coated with a cover layer consisting of such a polymer, and wherein the lid ring has, on an end face facing the lid part, at least one circumferential projection, which is sealed to the layer of peelable plastic material and/or to the cover layer of the lid part; or

the lid ring has, on a side facing the lid part, at least one layer of a peelable plastic material, wherein the layer of peelable plastic material contains at least one sealable, thermoplastic polymer and/or is coated with a cover layer consisting of such a polymer, and wherein the lid part has, on an end face facing the lid ring, at least one circumferential projection, which is sealed to the layer of peelable plastic material and/or to the cover layer of the lid part; and

the lid ring has, on an end face facing the lid part, at least two circumferential projections arranged essentially parallel, which are sealed to the layer of peelable plastic material and/or to the cover layer of the lid part; or

the lid part has, on an end face facing the lid ring, at least two circumferential projections arranged essentially parallel, which are sealed to the layer of peelable plastic material and/or to the cover layer of the lid ring,

wherein a distance between the circumferential projections is at most 3 mm.

2. A lid assembly in accordance with claim 1, wherein at least two circumferential projections of the lid ring or of the lid part are arranged essentially concentrically with a radial distance that is at most 3 mm.

3. A lid assembly in accordance with claim 1, wherein the lid ring or the lid part has exactly two circumferential projections on the end face thereof.

4. A lid assembly in accordance with claim 1, wherein the distance between the circumferential projection is between 0.3 mm and 3 mm.

5. A lid assembly in accordance with claim 1, wherein the circumferential projections have a height between 0.05 mm and 0.4 mm.

6. A lid assembly in accordance with claim 1, wherein a cross section of the circumferential projections tapers to a point toward a free end of the circumferential projections.

7. A lid assembly in accordance with claim 1, wherein circumferential projections have an essentially triangular cross section.

8. A lid assembly in accordance with claim 1, wherein the lid part has a thickness totaling at least 0.2 mm.

9. A lid assembly in accordance with claim 1, wherein at least the lid part has at least one additional layer in the form of an essentially gas-tight and liquid-tight barrier layer.

10. A lid assembly in accordance with claim 1, wherein the lid part has at least one circumferential projection, which projects in a direction of the lid ring and has a cross section that is adapted to a contact surface of the lid ring, which said contact surface is complementary to the lid part, such that the lid part can be fixed to the lid ring after a first-time separation from the lid ring, and the lid part is especially sealingly in contact with the contact surface thereof.

11. A packing container comprising:

a sleeve;

a lid assembly comprising a lid ring consisting of a plasticizable, thermoplastic polymer material, and a dimensionally stable lid part, which can be placed on the lid ring , wherein:

the lid part has, on an end face facing the lid ring, at least two circumferential projections arranged essentially parallel, which are sealed to the layer of peelable plastic material and/or to the cover layer of the lid ring, wherein

a distance between the circumferential projections is at most 3 mm and

the lid ring is fixed at one end of the sleeve in an essentially gas-tight and liquid-tight manner.

12. A packing container in accordance with claim 11, wherein the sleeve has an essentially gas-tight and liquid-tight inner lamination.

13. A packing container in accordance with claim 12, wherein the inner lamination of the sleeve has at least one layer consisting of a sealable plastic material, which is sealed to the lid ring of the lid assembly.

14. A method for manufacturing a lid assembly comprising a lid ring consisting of a plasticizable, thermoplastic polymer material, and a dimensionally stable lid part, which can be placed on the lid ring , wherein:

a distance between the circumferential projections is at most 3 mm, the method comprising the steps of:

placing the lid part on the lid ring; and

energizing the lid part with ultrasound, wherein the layer of peelable plastic material and/or the cover layer of the lid part or of the lid ring is sealed ultrasonically to the at least two circumferential projections of the lid ring or of the lid part while a fused connection is formed between the circumferential projections.

15. A method in accordance with claim 14, wherein the lid part is energized by means of at least one sonotrode, which extends at least essentially around an entire circumference of the at least two circumferential projections of the lid ring or of the lid part.

16. A method in accordance with claim 14, further comprising providing a sleeve of a packing container, wherein the lid ring is placed first on the sleeve of the packing container and the lid part is then sealed ultrasonically to the lid ring.

17. A method in accordance with claim 16, wherein the lid ring is sealed to an inner lamination of the sleeve, which has at least one layer consisting of a sealable plastic material.