Packaging material

Abstract

A packaging laminate includes a core layer (or web) with through-holes covered on one side with a first outer layer, and on another side with a second outer layer, such that the first and second outer layers are sealed to each other within the through-holes. To provide a permanent seal between the outer layers, the web can be flame-treated to activate or polarize parts of the first outer layer within the through-holes.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a divisional of, and claims priority under 35 U.S.C. § 120 to, U.S. patent application Ser. No. 10 / 258,969, which was filed on Mar. 13, 2003, as a 371 of International Application No. PCT / SE01 / 00985, filed on May 7, 2001, and this application claims priority under 35 U.S.C. § 119 to Swedish Patent Application No. 0001677-4, filed on May 8, 2000. The entire contents of each of these applications are hereby incorporated by reference in this application.FIELD OF THE INVENTION [0002] The present invention relates to a method of producing a packaging material comprising a core layer with through-going holes which are covered by a first layer applied on one side of the core layer, and a second layer applied on the other side of the core layer, the first and second layers being bonded to one another within the regions of the opening contour of the through-going holes, the method comprising the steps of providing a web of co...

AI Technical Summary

Benefits of technology

[0014] A further object of the present invention is to realize a simple, but efficient method of producing a packaging material for a packaging container with a well-functioning opening arrangement of the type described above.

[0015] One particular object of the present invention is to realize a method of producing a packaging material for a packaging container with an opening arrangement of the type described above, which ensures an efficient and expedient opening function of the packaging container also in that case when the container wall includes an aluminum foil in at least one of its two outer layers.

[0019] As a result of the above-disclosed surface treatment by means of so-called flame-treating, a polarization or activation will be achieved of the bonding sites on the parts of the first outer layer accessible from the second, or uncoated, side, the polarized or activated bonding sites ensuring a permanent seal between the first and second outer layers when the second outer layer, in a subsequent coating operation, is applied to the web.

[0022] In order further to improve the sealing bond between the first layer of thermoplastic and the paper or paperboard web, the first thermoplastic layer is extruded preferably during the supply of, or in an atmosphere of ozone, which activates and / or generates bonding seats or sites in the surface of the thermoplastic layer so that the thermoplastic layer is sealed to the one side of the web with high sealing strength.

[0023] In order to amplify the sealing strength between, on the one hand, the web and the sealing- or lamination layer and, on the other hand, between the sealing- or lamination layer and the aluminum foil of the second outer layer, the sealing- or lamination layer is preferably also extruded during the supply of, or in an atmosphere of ozone which activates and / or generates the bonding seats or sites in the surface of the sealing- or lamination layer so that this layer, with good sealing strength, can be sealed to both the web and to the aluminum foil.

[0027] As in the earlier embodiment, the sealing strength between both the web and the extruded sealing- or lamination layer and between the sealing- or lamination layer and the aluminum foil can also be improved if the sealing- or lamination layer is extruded under the supply of, or in the presence of an atmosphere of ozone which activates and / or generates active bonding seats in the extruded surface of the sealing- or lamination layer so that this layer is sealed and bonded to the web and the aluminum foil, respectively, with high sealing strength.

Problems solved by technology

Both of these preconditions are, as a rule, easy to satisfy with packaging containers in which both of the respective outer layers of the packaging material consist exclusively of simple, easily sealed thermoplastic layers, while, on the other hand, it is not an uncommon occurrence that problems arise in packaging containers in which one or both of the outer layers of the packaging material also include a layer of another material than thermoplastic, such as, for example, an aluminum foil which is often employed in packaging containers for oxygen gas-sensitive products, such as juice, etc.

When the outer layer on the inside of the packaging wall also includes an aluminum foil which, by the intermediary of a sealing- or lamination layer, is connected to the outer layer on the inside of the packaging wall within the region of the opening contour of the hole, it occasionally happens that the seal between the two outer layers of the packaging wall is unintentionally ruptured when the opening strip or pull-tab is pulled off, and that the outer layer on the inside of the packaging wall at best is only partly removed from the hole.

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