Tear-Off Lid and Method For Its Manufacture
The invention relates to a lid ring (20′) for production of a tear-off lid, whereby a hot-sealing coating (62) is only applied to the edge (68) of the dispensing opening (25). A material saving is thus possible relative to conventional full-surface application. A coating different from the hot-sealing coating can form the lid ring surface outside the hot-sealing coating.
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This application claims the priority of Swiss patent application No. 453/05, filed on Mar. 17, 2005, the disclosure of which is incorporated herein by reference in its entirety.
BACKGROUNDThe invention relates to a tear-off lid comprising a lid ring with a take out opening covered by a tear-off foil and wherein lid ring and tear-off foil are releasable connected to each other by a hot sealable plastic coating in a connection area around the edge of the take out opening. Further the invention relates to a container with a tear-off lid. Still further the invention relates to a method for the manufacture of a tear-off lid wherein a tear-off foil is fixed by a hot sealable material to a ring shaped lid with a take out opening.
PRIOR ARTIt is known to provide lids on containers in the form of cans or boxes, respectively, as ring shaped lids, in particular metal lids, being permanently fixed to the container and being provided with a take out opening in said lid which is closed by a tear-off foil, and in particular a tear-off metal foil, fixed to the ring shaped lid by hot sealing up to the first use of the contents of the package. Such lids are known as tear-off lids. An additional plastic cover that is arranged over the metal lid provides a closure for the package during the consumption time of the contents of the package. It is known to make the ring shaped lid from a starting material coated on its whole surface wherein a heat sealable coating of polypropylene or a coating containing polypropylene has been provided on the whole surface of the upper face of the starting material where the tear off foil will be hot sealed. This coating is subject to the manufacturing steps during forming of the ring shaped lid. From WO 01/07330 it is known to apply the hot sealable full surface coating of the ring shaped lid only after the forming thereof.
SUMMARY OF THE INVENTIONIt is the object of the invention to improve a tear-off lid of the mentioned kind.
This object is met by a tear-off lid with the characterizing features of claim 1.
By limiting the hot sealable coating to the border of the take out opening or only to the connection area and thus essentially to the actual sealing area, it is possible to save a considerable amount of hot-sealing material. It has been found that the hot sealable coating material has disadvantages for the forming of the lid outside of the sealing area and for example is frequently damaged during flanging. Outside of the sealing area a different coating of the lid can be provided, for example a coating made of PET (polyethylene terephthalate) which is already known in the prior art as the coating on the lower face (thus as the coating facing the contents of the container). In this case the PET-coating may lie beneath the hot sealable coating within the connection area or the border of the take out opening, respectively, or may be omitted there. The hot sealable coating is preferably a polypropylene coating or a coating containing polypropylene, but other hot sealable substances can be used as well.
Another object of the invention is to provide a method for the manufacturing of tear-off lids.
This object is met for the method mentioned at the beginning with characterizing features of claim 9.
In special embodiments of the method the hot sealable coating is applied before applying and sealing of the foil only on the border or the connection area, respectively, on the one hand to the preformed or formed ring shaped lid or on the other hand to the not yet formed starting material on the areas that later form the border or the connection area, respectively.
In another embodiment the hot sealable coating is specifically applied as well to the preformed ring shaped lid on the special flange (so called “retort-curl”) of the edge of the take out opening.
In both embodiments the hot sealable coating can be applied to the bare metallic lid ring or on the bare metallic starting material (wherein the metal may be a metal with a metallic coating) or on the other hand the hot sealable coating can be applied to a lid ring that is already provided with a non metallic coating or on a starting material that is already provided with a non metallic coating and wherein said non metallic coating is not suitable for hot sealing and is for example a PET coating.
Further embodiments, advantages and uses of the invention follow from the dependent claims and from the following description and the drawings, wherein:
Known methods and apparatus for making metal lids with tear-off foils are shown in prior art
As already explained the coating may cover on the one hand the whole border 68 of the take out opening as shown with coating 62 of
Further
In the shown preferred embodiment the conveying apparatus comprises two toothed belts 31 and 32, in particular lying with their surfaces in the same planes and thus running coplanar and being led over pulleys 34, 36 at the beginning and end of the conveying apparatus so that an endless toothed belt drive in the necessary length for the number of working stations is provided. A step motor or a servo motor driving the belts by toothed rollers, as can be seen in the Figure with motor 33 and driving axle 38, provides the stepwise toothed belt movement synchronized with the working stations. If further conveying apparatus, as apparatus 30′ are provided, their toothed belts can be driven by the same motor over additional driving axles or they may be provided with their own motor drive. Motor 33 is controlled by a control 37 for making the step by step forward movement which control 37 may be a common control for the lid making apparatus, which controls as well the working stations and the station 9, or which control 37 is a control for the conveying apparatus only which is in communication with a master control for the lid making. Motor 33 and the other drive components for the toothed belts are arranged on a machine bed 35 of which only feet 35 are shown. Dogs are connected to the toothed belts which are depicted in
It is preferred that the distance between the toothed belts 31 and 32 can be set whereby the distance of opposing dogs 40 of the toothed belts can be adjusted to adapt the conveying apparatus to different object sizes. To this end transverse links 58 are provided which allow a simple setting of the distance between the toothed belts. The drive axle 38 is adapted to allow such a distance setting. The distances between dogs 40 on each toothed belt are given by the spacing of the teeth of the toothed belt and the fixation of the dogs. This distance can preferably be changed to adapt to the object size by changing the toothed belts to another set of toothed belts having dogs with a different distance to each other. In this way the preferred take up size can be provided by setting the distance between the toothed belts and changing to toothed belts with different distances between the dogs. Thereby a changeover to different object sizes can be done for all dogs at the same time and quickly. The manufacturing steps described for the tear-off lids and the corresponding working stations and conveying apparatus are to be understood as examples only and serve for the understanding of the invention. The invention can be practiced as well for tear-off lids manufactured in a different way.
For both embodiments described of the manufacturing and conveying apparatus, respectively, wherein the heat sealable coating is applied to the lid ring, it is necessary to provide a corresponding working station along the conveying path and of course ahead of the heat sealing station. For those embodiments where the coating is applied to the starting material, the coating is already present on the lid blanks at the beginning of the shown manufacturing and conveying paths, respectively, and as well on the material of the tear-off foil that only needs punching.
While there are shown and described presently preferred embodiments of the invention, it is to be understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims.
Claims
1. Tear-off lid having a lid ring (20′) with a take out opening (25) covered by a tear-off foil (25″), wherein said lid ring and said tear-off foil are releasable connected to each other with a heat sealable coating (62) along the border (68) of said take out opening by a connection area, characterized in that said lid ring is not coated or is coated with a plastic coating different from said heat sealable coating (62) outside of said border or said connection area.
2. Tear-off lid according to claim 1, characterized in that the heat sealable plastic coating is a polypropylene coating or a coating containing polypropylene, and in particular a polypropylene containing lacquer coating.
3. Tear-off lid according to claim 1, characterized in that the plastic coating different from the heat sealable coating is a polyethylene terephthalate coating or a coating containing polyethylene terephthalate.
4. Tear-off lid according to claim 1 characterized in that the plastic coating different than the heat sealable coating extends on one side or on both sides over the whole lid ring and therefore lies in the connection area beneath the heat sealable coating.
5. Tear-off lid according to claim 1, characterized in that the lid ring comprises a flanged edge (67) beaded towards the take out opening (25′) and that the flange is covered by the heat sealable coating.
6. Tear-off lid according to claim 1, characterized in that the lid ring is made of metal.
7. Tear-off lid according to claim 1, characterized in that the lid ring or the take out opening is round or oval or rectangular or is provided with another non round shape.
8. Container with a tear-off lid according to claim 1.
9. A method for manufacturing a tear-off lid wherein a tear-off foil (25) is connected to a lid ring (20′) with a take out opening (25) by heat sealing of a heat sealable material, characterized in that the heat sealable material (62) is applied on the lid ring only to the border (68) of the take out opening (25) or in the connection area with the tear-off foil and/or that the heat sealable material (65) is applied only to the border of the tear-off foil.
10. Method according to claim 9 characterized in that the heat sealable material (62, 65) is applied on the starting material (60) before a forming or punching thereof.
11. Method according to claim 9 characterized in that the heat sealable material (62, 65) is applied after a forming of the lid blank (20) or lid ring (20′) or after a punching of the tear-off foil.
12. Method according to claim 9, characterized in that the heat sealable material is applied in liquid form or is laid on as a solid band.
13. Method according to claim 9, characterized in that the lid ring (20′) is provided with a flange directed upwardly and inwardly (67; retort curl) and that the heat sealable coating is applied so that the flange is at least partly covered.
14. Method according to claim 9, characterized in that the lid ring or its starting material, respectively, is provided at least on one side and preferably on both sides with a plastic coating that is not suitable for heat sealing.
15. Method according to claim 14, characterized in that the coating not suitable for heat sealing extends beneath the heat sealable coating (62) by applying the latter as a layer on the coating not suitable for heat sealing.
16. Method according to claim 9, characterized in that the lids are conveyed on a linear conveying apparatus by toothed belts or by chains to the working stations and in particular to the heat sealing station, as the case may be with a preceding working station along the conveying path wherein the heat sealable coating is applied to the lid rings following each other.
Type: Application
Filed: Mar 13, 2006
Publication Date: Sep 18, 2008
Applicant: Soudronic AG (Bergdietikon)
Inventor: Marcel Oberholzer (Kindhausen)
Application Number: 11/908,817
International Classification: B65D 41/32 (20060101); B65B 51/10 (20060101);