WO2010013220A1

WO2010013220A1 - Process for the production of film for packaging with one-way valves and reel obtained

Info

Publication number: WO2010013220A1
Application number: PCT/IB2009/053327
Authority: WO
Inventors: Claudio Ernestino Zanarella
Original assignee: Claudio Ernestino Zanarella
Priority date: 2008-07-30
Filing date: 2009-07-30
Publication date: 2010-02-04
Also published as: ITPD20080231A1

Abstract

A new process is described for the production of polylaminate film (F) for packaging and the reel obtained, comprising the phases of unwinding (1) of an inner film (N) and an outer film (E), application (3) of adhesive substance (C) on the bonding surface of said inner film (N) and/or of said outer film (E), with the exception of localised areas (N1, E1); bonding (5) of said outer film (E) with said inner film (N) so that the respective said localised areas (E1, N1) are opposite each other, creation (6, 7) of one or more holes (N2, E2) on said inner film (N) and on said outer film (E), in each of said localised areas (N1, E1) and wherein said holes (N2) of said inner film (N) do not overlap said holes (E2) of said outer film (E); rewinding (8) of said polylaminate composite film (F) on a reel.

Description

PROCESS FOR THE PRODUCTION OF FILM FOR PACKAGING WITH ONE-WAY VALVES AND REEL OBTAINED

DESCRIPTION

The present patent relates to hermetic packaging for products of various types - food, chemical or other - and in particular concerns a new process for the production of polylaminate film for packaging with one or more incorporated one-way valves and film in reels obtained. Currently, for the conservation of products of various types — food and/or chemical - widespread use is made of packages or containers or wrappings which are in general hermetically sealed, suitable for preventing air from the outside getting into the package, thus preventing oxygen, responsible for the processes of oxidisation, from coming into contact with the product contained. In particular, the known packaging materials used for the production of packages and bags in general comprise two or more polylaminate films, of which at least one internal film is made of polymeric plastic material, for example polyester, polyethylene, polyvinyl chloride, polypropylene, polyamide, etc. and/or aluminium foil. Said materials are characterised by high strength and chemical inertia, suitable for contact with many chemical and/or food substances and products. After packaging of the product to be conserved, the gas contained in the package or bag or container in general is extracted to create a vacuum and said packaging is then hermetically sealed. Since said vacuum packs or bags are hermetically sealed, they do not permit the outflow of any gases that may be released by the product contained inside.

For example coffee, in grains or powder, packed in bags after roasting, releases a large quantity of CO₂ entailing an increase in pressure inside the bag and therefore swelling of the bag, with the danger of damaging the packaging, for example causing rupture of the seal lines and consequent bursting.

To solve said drawback, packages or bags provided with one-way valves are known, suitable for permitting outflow of the gas contained inside the package when certain overpressure values are reached, while they prevent the outside air, and therefore O₂ and water vapour, penetrating the inside of the package, affecting the characteristics of the product and even damaging it.

Said one-way valves are used for example in bags of coffee, particularly in grains, in packages of cheese and fresh products in general, in bags of animal food, etc.

The known one-way valves are substantially discs applied to the packaging during the production phase.

The known bag packaging is produced by lines where the films in reels are bonded, shaped and sealed in continuous mode; however, application of the one-way valve is not performed in continuous mode, to the disadvantage of production efficiency and speed.

The bags with one-way valves of the known type furthermore have a considerable cost, which makes them uneconomical compared to the vacuum packs without valve. Steam-cooking of food is known, very popular due to the fact that the nutrients contained in the food are broken down and dissolved in water to a lesser extent than in boiling, for example. Steaming, like boiling, also takes time, with considerable consumption of fuel and electricity.

Furthermore, for steaming, at least two containers have to be used on top of each other, the lower one containing the water and the upper one containing the food to be cooked. It should furthermore be noted that steaming also involves a certain loss of nutrients, especially vitamins and mineral salts, which are washed away by the steam and at the end of cooking are dissolved in the condensed water accumulated on the bottom of the lower container. This water is thrown away and not used, with consequent total loss of the nutrients dissolved in it.

To remedy all said drawbacks a new process has been studied and developed for the production of polylaminate film for packaging of products of various types - food, chemical or other - with incorporated one-way valves, and polylaminate film in reels obtained. The main aim of the present invention is to optimise the continuous production process of the package with one-way valve/s incorporated in the polylaminate film in reels.

A further important object of the present invention is to guarantee the correct conservation of chemical and/or food products packaged with the polylaminate film, which must be protected from oxidisation or degenerative processes in general induced by contact of the product with the air. The valve/s incorporated in the packaging obtained by the new polylaminate film permits the passage of gases such as water vapour, CO₂ or other, in one single direction, i.e. from the inside of the packaging towards the outside, while it prevents the inflow of air from the outside.

Furthermore, due to said incorporated one-way valve, no overpressures occur inside the package due to the release of gases by the products contained, thus there is no risk of damage or undesired breakage of the packaging.

A further important object of the present invention is to produce packaging without any encumbrance outside or inside the packaging due to the presence of one or more one-way valves, which are incorporated in the polylaminate film and obtained by particular work processes performed on the films in reels.

A further important advantage consists in the fact that the new oneway valve is not in any way visible from the outside of the package. A further important object is to guarantee the hermetic seal of the package obtained using the new film, by interposing if necessary a silicone or rubbery substance or soft plastic or thermoadhesive substance, suitable for sealing the opening/s of the valve in the absence of overpressures inside the package.

A further important object is to produce packages suitable for use in microwave oven cooking, since said one-way valve permits venting of the water vapour generated by the food products inside the package during cooking, without having to open the package beforehand, thus eliminating the risk of the package tearing or bursting. A further important object of the present invention is to produce packages for the steaming of food in a microwave oven, capable of maintaining the internal pressure at ideal values for steaming, limiting and controlling outflow of the steam.

These and further objects, direct and complementary, are achieved by the new process for the production of polylaminate film for packaging of products of various type, with incorporated one-way valves, and polylaminate film in reels obtained.

The new process provides for the use of two or more films to be bonded, where each of said incorporated one-way valves is obtained by overlapping corresponding localised areas of said laminate films. Said new polylaminate film comprises in particular at least one outer film, suitable for constituting the outer surface of the film and wrapping or package obtained from said film, coupled with at least one further inner film, suitable for constituting the inner surface of the film and wrapping or package obtained. Said outer film comprises at least one localised area on which one or more through holes are obtained. Analogously, said inner film comprises at least one localised area on which one or more further through holes or openings are obtained, and where said outer and inner films are bonded so that the relative said localised areas are overlapped, while said holes of the outer film and said holes of the inner film do not directly communicate, i.e. they are not overlapped or partially overlapped.

Said outer film and said inner film are bonded and sealed according to the known processes with the exception of said localised areas, where no adhesive substance is positioned between said inner film and said outer film.

In said localised areas at least one layer can be interposed made of a material suitable for guaranteeing a hermetic seal between said inner film and said outer film, for example a soft layer, such as paint or a rubbery or silicone substance or a soft plastic. Alternatively between said inner film and said outer film, in at least part of said localised area, preferably in the part not corresponding either to the holes of the inner film or the holes of the outer film, a thermoadhesive substance can be applied which guarantees the seal between said inner film and said outer film, preventing the passage of gas through said holes, until the melting temperature of said substance is reached.

The new polylaminate film therefore comprises a plurality of one-way valves, identified by said perforated localised areas, where said oneway valves are closed, preventing the passage of gas, when said localised areas of the inner and outer films adhere, and open when an overpressure acting on said inner film causes the detachment of said localised areas, permitting the passage of gas from the inside to the outside via said holes. Said new polylaminate film with one-way valves is therefore obtained by a continuous process, unlike the known processes in which application of the one-way relief valves requires interruption of the production process.

The new process basically comprises the following phases: . application of adhesive substance on the bonding surface of said inner film and/or of said outer film, with the exception of localised areas distributed at constant or modular pitch on said films; • application if necessary of said soft layer and/or thermoadhesive substance in said localised areas; . bonding of said outer film with said inner film so that the relative localised areas are opposite each other;

. creation of one or more through holes on said inner film corresponding to each of said localised areas and creation of one or more through holes on said outer film corresponding to each of said localised areas, where the holes of the inner film are in positions not corresponding to the holes of the outer film, i.e. they are not overlapping or partially overlapping;

. rewinding of the poly laminate film thus obtained on a reel. In detail, production of the new type of polylaminate product entails firstly the use of at least one polymeric plastic and/or aluminium film in a reel to be used for the inner lining of the package, i.e. in material suitable for contact with the product to be packaged, for example a food or chemical product, and at least one polymeric plastic film in a reel, suitable for use as the outer part of the package. In the preferred solution, said inner film is made of polyester or polyethylene or polyvinyl chloride or polypropylene or polyamide or other, if necessary bonded with at least one further aluminium film, where said films are used for the inner lining of the package and will be in contact with the product to be conserved.

Said outer film is also preferably made of polyester or polyethylene or polyvinyl chloride or polypropylene or polyamide or other, and can be produced in accordance with known processes. Said holes or openings of specific size in said localised areas of said inner and outer films are for example made using laser, mechanical, electrical or thermal devices, etc. In particular, in the preferred solution, said holes are made by means of mechanical punching machines with controlled depth punch. According to one of the possible embodiments, in said localised areas of said inner and outer film/s, at least one soft layer is interposed made of rubbery or silicone or plastic material, having the twin function of guaranteeing the hermetic seal between the films, substantially determining the closure of said holes made both on the outer and inner film/s, and permitting detachment of the localised area of said outer film/s from the corresponding localised area of said inner film/s. The new polylaminate film with one-way valves is applied in particular in the packaging of food and/or chemical products, but can also be used for products and objects of other types. The package obtained therefore comprises a portion of said new polylaminate film folded and closed hermetically and comprises at least one of said one-way valves. Any increase in pressure inside the hermetic package obtained, due to the release of gas by the product contained, causes detachment of the outer film/s from the inner fϊlm/s only in said localised area with soft layer, so that the gas present inside the package is released to the outside via the holes provided on said inner film/s, creating an air chamber between inner film/s and outer fϊlm/s.

The gas contained in said air chamber is therefore released to the outside via the hole/s made in said outer fϊlm/s. In this way, when the inner pressure, due to the outflow of gas, i.e. degassing of the environment inside the package, drops until it balances the outer pressure, the area of outer film comes to rest again in the corresponding area of inner film, so that the holes are blocked and the seal is guaranteed by the presence of said soft layer, which acts as a gasket. Therefore, the one-way valve permits outflow of the gas in overpressure inside the package while preventing the introduction of air, water vapour and oxygen from the outside to the inside of the package.

According to a possible further embodiment, a layer of thermoadhesive substance is applied between said localised areas of said inner and outer films. The new film thus obtained is therefore also suitable for the production of hermetic packages for microwave cooking, each comprising one or more of said one-way valves. The increase in pressure and temperature inside the package resulting from microwave cooking, which causes evaporation of the water contained in the food to be cooked, causes melting of the thermoadhesive substance permitting detachment of said localised area of the outer film from the inner film, allowing the gas to flow out of the package.

Said package, as above, furthermore permits control of the internal pressure, since the flow rate of the steam flowing through said holes is determined and limited by the diameter of the holes. Said holes, in fact, permit outflow of the water vapour due to internal overpressures and prevent said outflow when the inner pressure is below certain limit values. The one-way valve is completely incorporated in the thickness of the polylaminate product, can be produced in continuous mode on films in reels, has no protruding thickness and is not visible from the outside of the package. The characteristics of the present invention will be better clarified by the following description with reference to the drawing attached by way of non-limiting example.

Figure 1 schematises the new process for the production of polylaminate film (F) with incorporated one-way valves (V) for the production of hermetic packages (J, K). Figure 2 shows in section a portion of the new polylaminate film (F), with one-way valve (V), obtained by overlapping localised areas (Nl, El) of an inner film (N) and an outer film (E) respectively. Figure 3 schematises, in section, operation of the one-way valve (V), where the localised area (El) of the outer film (E) detaches from the corresponding localised area (Nl) of the inner film (N) due to an overpressure acting on said inner film (N), generated by gas (W). Figure 4 schematises a possible application for the production of a package (J) for example for use in the microwave cooking of food, with one or more one-way valves (V) on the upper part of the package (J).

Figure 5 schematises a possible alternative embodiment of the new polylaminate film (F) with one-way valve (V).

Figure 6 schematises a further possible configuration of a package (K) with one-way valves (V). The new process for production of the polylaminate film comprises the phases of: unwinding (1) of a film (N) suitable for acting as inner film;

• unwinding (2) of a film (E) suitable for acting as an outer film;

• application (3) of adhesive substance (C) on the bonding surface of said inner film (N) and/or said outer film (E), with the exception of localised areas (Nl, El) distributed over said films (N, E) at constant or modular pitch;

• application (4) if necessary of a soft layer (G) and/or thermoadhesive substance (H) in said localised areas (Nl, El) of said inner film (N) and/or said outer film (E);

• bonding (5) of said outer film (E) with said inner film (N) so that the relative localised areas (El, Nl) are opposite each other;

• production (6) of one or more through holes (N2) or openings on said inner film (N) in each of said localised areas (Nl), and production (7) of one or more holes (E2) of the outer film (E) in each of said localised areas (El), where the holes (N2) of the inner film (N) are in positions not corresponding to the holes (E2) of the outer film (E), i.e. they are not overlapping or partially overlapping; • rewinding (8) on a reel of the polylaminate composite film (F) thus obtained.

The polylaminate composite film (F) thus obtained therefore comprises at least two bonded films (N, E), an outer film (E) and an inner film (N), and a plurality of incorporated one-way valves (V) arranged at constant or modular pitch. Said incorporated one-way valves (V) are obtained by the overlapping of said non-glued localised areas (Nl, El) of said films (N, E). The increase in pressure inside the hermetic package (J, K) obtained using the new polylaminate film causes detachment of the outer film (E) from the inner film (N) only in said localised area (El, Nl), i.e. where there is no adhesive substance (C), so that the gas or water vapour (W) present inside the package flows out via the holes (N2) provided in said inner film (N), creating an air chamber (Cl) between inner film (N) and outer film (E). The gas or water vapour (W) contained in said air chamber (Cl) therefore flows out via the holes (E2) provided in said outer film (E),

(figure 3).

Between said inner film (N) and said outer film (E), in said localised areas (El, Nl), preferably where said holes (N2, E2) are not present, thermoadhesive glue (H) can be applied so that said localised areas adhere to each other, guaranteeing hermetic closing of the valve (V) as long as the temperature remains below the melting value of the thermoadhesive glue.

The package (J) obtained by the use of said new polylaminate film (F) with one-way valves (V) can also be used for microwave cooking. In fact, at a temperature below said melting temperature of the thermoadhesive substance (H), the package (J) is hermetically closed, whereas when said melting temperature is reached, during microwave cooking, with consequent increase in pressure due to the generation of water vapour by the product contained in the package (J), said thermoadhesive substance (H) melts and said outer film (E) detaches from said inner film (N) in said localised areas (El, Nl), identifying said chamber (Cl), permitting outflow of the gas (W) from the inside of the package (J). Figure 5 shows a further possible embodiment of the new polylaminate film with one-way valve (V), comprising an inner film

(N) in turn obtained by the bonding of a plastic film (Na) and an aluminium film (Nb), and an outer plastic film (E), said outer film (E) and inner film (N) being bonded by the interposition of an adhesive substance (C) with the exception of respective localised areas (Nl, El) in which through holes (E2, N2) are made in positions not overlapping or partially overlapping.

Between said localised areas (Nl, El) at least one soft layer (G) can be interposed, for example paint or rubbery or silicone substance or soft plastic acting as a gasket. Said soft layer (G) guarantees a seal in the absence of overpressure acting on said inner layer (N) but permits detachment between said inner layer (N) and said outer layer (E) in the event of overpressures acting on said inner layer (N).

Figure 6 schematises a possible application for the production of a package for coffee (K) for example, with one or more one-way valves

(V) on the side of the package (K).

Therefore with reference to the preceding description and the accompanying drawings the following claims are made.

Claims

1. Process for the production of polylaminate film (F) for packaging comprising two or more films (N, E) bonded by means of adhesive substances (C), at least one inner (N) and at least one outer (E) film, and one or more one-way valves (V), characterised in that it comprises the phases of:

• unwinding ( 1 ) of said inner film (N);

• unwinding (2) of said outer film (E);

• application (3) of adhesive substance (C) on the bonding surface of said inner film (N) and/or said outer film (E), with the exception of localised areas (Nl, El) arranged in succession at constant or modular pitch;

• bonding (5) of said outer film (E) with said inner film (N) so that the respective said localised areas (El, Nl) are opposite each other; • creation (6) of one or more through holes (N2) or openings on said inner film (N), in each of said localised areas (Nl), and creation (7) of one or more through holes (E2) or openings on said outer film (E), corresponding to each of said localised areas (El); and wherein said holes (N2) of the localised areas (Nl) of said inner film (N) are in positions not corresponding to said holes (E2) of the localised areas (El) of said outer film (E), i.e. they are not overlapped or partially overlapped.

2. Process for the production of polylaminate film (F) for packaging, according to claim 1, characterised in that it comprises the phase of rewinding (8) said polylaminate composite film (F) on a U

reel.

3. Process for the production of polylaminate film (F) for packaging, according to claims 1, 2, characterised in that it comprises, upstream of said bonding phase (5) of said inner film (N) and outer film (E), the phase of application (4) of a soft sealing layer

(G) on the bonding surface of said inner film (N) and/or outer film (E), in said localised area/s (Nl, El).

4. Process for the production of polylaminate film (F) for packaging, according to claim 3, characterised in that said soft layer (G) is made of rubbery or silicone or plastic material.

5. Process for the production of polylaminate film (F) for packaging, according to claims 1, 2, characterised in that it comprises, upstream of said bonding phase (5) of said inner film (N) and outer film (E), the phase of application (4) of a thermoadhesive sealing substance (H) on the bonding surface of said inner film (N) and/or outer film (E), in said localised area/s (Nl, El), and wherein said thermoadhesive substance (H) has a lower melting point than the melting point of said inner film (N) and outer film (E).

6. Process for the production of polylaminate film (F) for packaging, according to the preceding claims, characterised in that said through holes or openings (N2, E2) are specifically sized and produced by means of laser and/or mechanical and/or electrical and/or thermal method.

7. Process for the production of polylaminate film (F) for packaging, according to the preceding claims, characterised in that said through holes or openings (N2, E2) are produced by means of rotary punching machines (61, 71) for punching the through holes (6, 7) respectively, at pre-defined depth, of said inner film (N) and said outer film (E).

8. Process for the production of polylaminate film (F) for packaging, according to the preceding claims, characterised in that said inner film (N) comprises at least one film (Nl) made of polymeric plastic bonded with at least one aluminium film (N2).

9. Process for the production of polylaminate film (F) for packaging, according to the preceding claims, characterised in that said outer film (E) is made of polymeric plastic material.

10. Reel of polylaminate film for hermetic wrappings or bags or packages comprising two or more films (N, E) bonded by means of adhesive substances (C), at least one inner (N) and at least one outer (E), produced as in one or more of the preceding claims, characterised in that it comprises a plurality of one-way valves (V) with modular or constant pitch, obtained by the overlapping, without interposition of adhesive substance (C), of at least one localised area (Nl) of said inner film (N) with at least one localised area (El) of said outer film (E), and wherein one or more through holes (N2) are obtained on said inner film (N), in said localised area (Nl) and in positions not overlapping or partially overlapping one or more through holes (E2) provided on said outer film (E) in said localised area (El).

11. Reel of polylaminate film, according to claim 10, characterised in that between said localised area (Nl) of said inner film (N) and said corresponding localised area (El) of said outer film (E), at least one soft layer (G) is interposed providing a seal, and wherein an overpressure of fluid (W) acting on said inner film (N) causes the detachment of said localised area (El) of said outer film (E) from said localised area (Nl) of said inner film (N), permitting the outflow of said fluid (W) through said holes (N2, E2).

12. Reel of polylaminate film, according to claim 10, characterised in that between said localised area (Nl) of said inner film (N) and said corresponding localised area (El) of said outer film (E) at least one layer of thermoadhesive substance (H) is interposed providing a seal, and wherein reaching of the melting temperature of said thermoadhesive substance (H) together with an overpressure of fluid (W) acting on said inner film (N) causes detachment of said localised area (El) of said outer film (E) from said localised area (Nl) of said inner film (N), permitting the outflow of said fluid (W) through said holes (N2, E2).