ES2273618T3 - PACK WITH VENTILATION AREA. - Google Patents

Abstract

Packaging comprises polymer film (1) with portions of the film (1) sealed together to form an enclosure for the food stuff, said sealed portions being sealed by a film-to-film seal except in a vent region (5) where a lacquer layer (6) is bonded to each portion of film before said portions are sealed together with the lacquer layers cohering, the seal strength of the lacquer-to-lacquer interface (6) being similar to that of the film-to-film interface under predetermined storage conditions, and the seal strength of said lacquer-to-lacquer interface (6) being reduced compared with that of the film-to-film interface at temperatures above those expected under said predetermined storage conditions so that the enclosure is vented to atmosphere by a cohesive peel action in the vent region (5) between said lacquer layers (6).

Description

Container with ventilation zone.

Technical sector

The present invention relates to containers of the type suitable for use with food items for the purpose of allow them to be cooked, for example in an oven microwave, keeping the container in its condition.

Containers of this type must form a envelope element with tightness to contain the items and prevent them from becoming contaminated during storage. In addition, for convenience, such containers must be adapted to allow water vapor to escape from the sealing element while cooking the item food, without having to pierce the container first. Have been given to know various ventilation arrangements for packaging of microwaves, which include wax plugs, waterproof closures weakened and leakage paths that ventilate, all, to increased temperatures and / or pressures. One of these packages is described in the document US-B-6582123.

An objective of the present invention is to give know an improved package of the type mentioned above that It is especially suitable for fresh food.

Description of the invention

According to the invention, the package comprises film of a polymer with parts thereof tightly bonded between yes in order to form an enveloping element for the article foodstuff, said parts being sealed together tightness by a watertight closure of film to film type except in a ventilation zone where a layer of varnish is join each part of the film before these parts are joined tightly with each other, blending the layers of varnish, the sealing resistance of the varnish interface being a varnish similar to the one with the low film to film interface predetermined storage conditions, and the sealing resistance of said varnish to varnish interface compared to the one that has the film-to-film interface to temperatures above those expected under these conditions of default storage, so that the envelope element is purged into the atmosphere by a detachment action or "peeled" cohesive in the ventilation zone between said layers of varnish.

Description of the drawings

The invention will be described by way of example with reference to the accompanying drawings, in which:

Figure 1 illustrates a package according to the invention;

Figure 2 shows a section through a air tight seal of the container of figure 1.

Way of carrying out the invention

The illustrated microwave package comprises a sheet (1) of oriented polypropylene film (OPP) that is folds on itself to gather opposite edges that are heat sealed each other along a waterproof back closure (2) to form a tube. The lower open end of the tubular sheet is closed at gather opposite parts of the lower edge and heat seal each other to form a lower seal (3). The container is filled then of food items and the open top end is closes by gathering opposite parts of the upper edge and at heat seal each other to form a tight top seal (4).

However, a part (5) of the seal upper (4) has a varnish to varnish interface between the two parts of the sheet (1) in order to form a tight seal capable to detach that extends across the full width (w) of the tight seal (4). The varnish is a coating (6) that is adheres to the inside of each of the opposite parts of the sheet (1) and that can be applied by a gravure process or flexographic printing before the sheet is shaped adopting the shape of the final wrapping element illustrated.

The varnish coating (6) can be a colorless, colored or opaque coating composed of resins or cellulose derivatives and a plasticizer in a solvent. Resin comprises a synthetic polymeric compound that looks like physically to natural resin, such as polyvinyl, polystyrene or epoxy A preferred example comprises a resin composition with EVA base and a solvent mixture comprising acetate  ethyl, isopropyl acetate and hydrocarbons such as naphtha no aromatic Said varnish is available as "Sovereign Proxseal J9683A ", varnish comprising an EVA copolymer dispersed in a solvent mixture of ethyl acetate and hydrocarbons aliphatic

The properties of tight seals, both those parts comprising tightly joined OPP sheet surface to surface, like those parts that incorporate the layer to varnish interface, are similar in resistance to ambient, cooling and freezing temperatures such as that occur when the container is being used to store food items. In addition, high humidity conditions caused by food items inside the container not unfavorably affect the resistance of the seal under environmental conditions, refrigeration and freezing. The high humidity conditions could include those that go up to 100% at 5-8ºC, but humidity conditions Typical comprise 85% or 95% at 5-8 ° C.

However, when the container is heated in a microwave oven to cook the food item, the resistance of that part of the seal (5) that incorporates the varnish coatings (6) is significantly reduced to high temperatures that are generated up to 100 ° C or higher, the resistance being only \ 30 g / 25 mm. This resistance reduced sealing of varnish to varnish type is such that allows a cohesive detachment, and provides a trajectory of open ventilation between the two parts of the OPP sheet to allow water vapor and pressurized gases to escape from inside of the container In contrast to this, the tight seal resistance in which the OPP sheet is tightly bonded surface to surface without intermediate varnish coatings remains high enough to keep the seal closed. From this way, the ventilation of the container is controlled so that it present only in the area (5) covered with varnish of the waterproof seal upper (4). Typically, the sealing resistance of the Watertight closure of varnish to varnish type is significantly reduced at temperatures of 60 ° C and higher.

The size of the ventilation zone (5) varnished is selected to provide a cross section of proper ventilation. If required, the ventilation zone (5) the entire length of the tight seal could be extended (4). Alternatively, the position of the varnished area (5) can be vary so that it is appropriate to the particular application and may be located in one or more of the other seals (2) and (3). Alternatively, multiple ventilation zones can be arranged (5) in one or more of the seams (2), (3), (4).

In alternative embodiments of the invention, the film may comprise any one of the following Compounds: polypropylene, polyethylene, polyester, polyamide, regenerated cellulose, polylactic acid, or a combination of any of them. The movie can also include movies With a heat-sealed coating.

The film can be adapted for a container of modified atmosphere forming microperforations in the same as are small enough to control the atmosphere Oxygen / carbon dioxide soda inside the bag. He food item will have a respiratory rate that is done match the natural permeability of the film and the additional permeability of microperforations for the purpose of produce the modified atmosphere required inside the container. Do not However, the total area of the microperforations would be too much small to have any significant effect on the water vapor permeability of the film or the need for Provide independent ventilation.

In addition, in alternative embodiments of the invention, the varnish may comprise an EVA varnish based on water or an epoxy / acrylic solvent based varnish.

Claims (10)

1. Container for food items, intended to be heated, comprising a sheet of a polymer (1) with parts of the sheet fixed together, in a sealed manner to constitute an envelope for the food product, characterized in that said parts are sealed by a seal of the laminar element to laminar element type, except in a ventilation zone (5), in which a lacquer layer (6) is attached to each of the laminar parts before said parts are tightly joined with each other, said lacquer layers coalescing, the sealing resistance of the lacquer-lacquer interface being similar to the interface of a laminar element with a laminar element under predetermined storage conditions, and reducing the sealing resistance of said lacquer interface to lacquer in comparison with that of the laminar element to laminar element interface at temperatures higher than those expected under said storage conditions nto predetermined, so that the envelope is vented to the atmosphere by a peeling action in the ventilation zone (5) between said lacquer layers (6). 2. Container according to claim 1, wherein said envelope is formed by sealing parts of the seal laminar element (1) with each other along multiple seams (2, 3, 4) with a ventilation zone (5) formed in one or several seams (4). 3. Package according to claim 2, wherein said envelope is formed by tightly joining parts of the laminar element with each other along multiple seams (2, 3, 4) with said ventilation zone (5) formed along the all of a seam (4), but not throughout the entire the length of all seams (2, 3). 4. Packaging, according to any of the previous claims, wherein the lacquer (6) is applied to the laminar element by a gravure printing process or flexography 5. Packaging, according to any of the previous claims, wherein the laminar element (1) It comprises polypropylene, polyethylene, polyester, polyamide, regenerated cellulose, polylactic acid, or a combination of any of the above. 6. Container according to claim 5, wherein The lacquer (6) comprises an EVA based resin. 7. Package according to claim 6, wherein The lacquer (6) comprises a combination of solvents comprising alcohols, esters and hydrocarbons. 8. Packaging, according to any of the claims 1 to 5, wherein the lacquer (6) comprises an EVA lacquer water based or a solvent based lacquer epoxy / acrylic. 9. Packaging, according to any of the previous claims, wherein the laminar element (1) is equipped with microperforations to withstand a modified atmosphere inside the package when it contains a food item that It requires breathing. 10. Laminar element for the production of a package according to any one of claims 1 to 9, wherein at least one area of the laminar element (1) adapted for its incorporation in a seal of the container between two parts of the laminar element, is provided with a coating of a lacquer (6) comprising an EVA based resin.