Patent Description:
Today, roll-fed packaging machines are commonly used for producing packages holding liquid food products. An advantage of using roll-fed packaging machines is speed. By continuously feed packaging material, folding this into a tube, filling food product into the tube, and sealing and cutting the tube in a lower end, food packages can be produced at impressive speed, e.g. <NUM><NUM> packages per hour. In addition to the impressive speed of roll-fed packaging machines, by having the food product held in the tube, unwanted microorganisms can efficiently be hindered from coming in contact with the food product. In this way it is made possible to produce so-called aseptic packages, that is, packages that can hold food products, such as UHT-treated milk, for several months in room temperature.

To achieve packages that can protect the food product for several months, several aspects must be considered. For instance, microorganisms should be hindered from coming in contact with the food product and sun light should be blocked out from reaching the food product, since this may deteriorate the food product. In addition, measures should be made for assuring that the packages can stand for several months. For instance, for carton packages, a protective strip, sometimes referred to as longitudinal sealing (LS) strip, can be applied inside the tube over the longitudinal sealing to provide for that the food product is hindered from coming in contact with a carton layer of the packaging material, thereby avoiding that this is dissolved by the food product.

Applying the protective strip onto the inside of the tube is today common practice for roll-fed carton packaging machines. To apply the protective strip, usually a polymer-based strip, this and the packaging material is first heated such that the protective strip and an inner plastic layer of the packaging material melt, and, secondly, the two are pressed together such that they adhere to each other.

To provide for that the protective strip adheres to both sides of the longitudinal sealing, part of the protective strip can first be attached to a first longitudinal edge of a web of packaging material and once this has been formed into the tube, the other part of the protective strip can be attached to the inside of the tube such that the joint of the tube, that is, the longitudinal sealing, is covered by the protective strip from an inside of the tube.

Further prior art can be found in <CIT> disclosing a unit for heat sealing a sealing strip to a strip of packaging material for pourable food products. It features a method where the strip of packaging material and the sealing strip are preheated. The nozzles are part of a single air heating system, sharing a common hot air supply that branches off to target the two different materials separately.

Even though application of protective strips has been used for many years and the technology behind has been developed and refined over the years, there is a need to further improve this process. For instance, by applying heat to melt the inner plastic layer of the packaging material, the packaging material is affected. By being able to reduce the impact of heat on the packaging material during the protective strip application, the risk that the packaging material is affected to the extent that defective packages are produced can be reduced. In addition, by being able to control this process in more detail, less heat is needed, which is positive from an environmental standpoint. Further, it is made possible to reduce the thickness of the different layers of the packaging material as well as the thickness of the protective strip, which is also environmentally beneficial.

It is an object of the invention to at least partly overcome one or more of the above-identified limitations of the prior art. In particular, it is an object to present a protective strip application process providing reliable adherence of the strip while reducing a risk of overheating the packaging material. A further object is to provide for that less material is needed for providing food safe packages.

According to a first aspect, it is provided a method for producing packages holding a food product according to claim <NUM>.

An advantage of heating the web by the first flow and the strip via the second flow is that individual heating of the two can be achieved. This provides for that a risk of over-heating can be reduced, resulting in that a risk of blisters being formed in the packaging material can be reduced, and that a risk of delamination in the packaging material can be reduced.

The individual heating also comes with the benefit that the strip and the web can be optimized for the sake of the strip application process individually. As an effect, it is made possible to use less material and/or material with lower carbon footprint, but still provide reliable food packages.

The first flow of heated air has a first temperature, and the second flow of heated air has a second temperature, wherein the first temperature is adjusted in accordance with properties of the packaging material, and the second temperature is adjusted in accordance with properties of the protective strip.

The first temperature may be in the range <NUM> to <NUM> degrees Celsius and/or the second temperature may be in the range <NUM> to <NUM> degrees Celsius.

The first flow of heated air provided via the first nozzle may be directed in a first flow direction and the second flow of heated air provided via the second nozzle may be directed in a second flow direction, and the first and second flow directions may be diverted at least <NUM> degrees.

By having the first and second flow directions diverted <NUM> degrees or more, it is made possible to ensure individual heating of the web and the strip.

The first flow of heated air has a first volumetric flow rate, and the second flow of heated air has a second volumetric flow rate, wherein the first volumetric flow rate may be adjusted in accordance with properties of the packaging material, and the second volumetric flow rate may be adjusted in accordance with properties of the protective strip.

An advantage with having different volumetric flow rates in the first and second nozzle is that the heated air may be supplied from the same source, but that different heating is achieved by different volumetric flow rates.

The web of packaging material may further comprise a barrier layer arranged between the outer protective layer and the inner protective layer, wherein the barrier layer may provide for that oxygen is hindered from passing through the packaging material into the food product, wherein the first temperature of the first flow and/or the first volumetric flow rate may be adjusted such that negative impact on the barrier layer is prevented.

Since disturbances of the barrier layer could result in loss of quality of the food produced held in the package, measures should be taken to assure that the integrity of barrier layers is maintained. By heating the strip and the web individually in combination with that the first flow and/or the first volumetric flow rate is chosen such that the barrier layer is not impaired, and it is made possible to produce packages with good quality and yet provide an individually adjusted heating of the strip.

The first and second temperature and/or the first and second volumetric flow rate may be set based on measured humidity level, measured pressure and/or measured temperature in surrounding air.

An advantage of taking into account the humidity level, the pressure and/or the temperature of the surrounding air is that the heating of the strip and/or the web can be dynamically set based on the specific conditions provided at the place of the heating arrangement. Thus, by both individually heat the strip and the web and also adjust based on the measurements made on the surrounding air, an even more reliable heating can be achieved with even less negative effects on the packaging material.

According to a second aspect, it is provided an apparatus for producing package holding a food product according to claim <NUM>.

The same features and advantages as presented above with respect to the first aspect also applies to this second aspect.

The first flow of heated air may have a first temperature and the second flow of heated air may have a second temperature, wherein the first temperature may be adjusted in accordance with properties of the packaging material, and the second temperature may be adjusted in accordance with properties of the protective strip.

The first flow of heated air may have a first volumetric flow rate, and the second flow of heated air may have a second volumetric flow rate, wherein the first volumetric flow rate may be adjusted in accordance with properties of the packaging material, and the second volumetric flow rate may be adjusted in accordance with properties of the protective strip.

The web of packaging material may further comprise a barrier layer arranged between the outer protective layer and the inner protective layer, wherein the barrier layer may provide for that oxygen is hindered from passing through the packaging material into the food product, wherein the first temperature of the first flow and/or the first volumetric flow rate may be adjusted to prevent negative impact on the barrier layer as well as on the packages produced.

The first and second temperature and/or the first and second volumetric flow rate may be set based on measured humidity level in surrounding air, measured pressure and/or measured temperature in surrounding air.

According to a third aspect, it is provided a kit of parts arranged to be mounted onto an existing filling machine according to claim <NUM>.

The same features and advantages as presented above with respect to the first and second aspect also applies to this third aspect.

The information can be restricted to materials being used, but it is also possible to include production data for the protective strip material and/or the packaging material, i.e. weighing in production parameters.

<FIG> generally illustrates a packaging machine <NUM>. In the illustrated example, the packaging machine <NUM> is a roll-fed carton packaging machine. The general principle of such a machine is that from a roll of packaging material PM, a web <NUM> is formed. Although not illustrated, if needed in order to fulfil food safety regulations, the web <NUM> may be sterilized using a hydrogen peroxide bath, a Low Voltage Electron Beam (LVEB) device or any other apparatus capable of reducing a number of unwanted microorganisms. After sterilization, by using a longitudinal sealing arrangement <NUM>, the web <NUM> can be formed into a tube <NUM>. When having formed the tube, a food product FP, for instance milk, can be fed into the tube <NUM> via a product pipe <NUM> placed at least partly inside the tube <NUM>.

In order to form a package <NUM> from the tube <NUM> filled with food product FP, a transversal sealing can be made in a lower end of the tube by using a transversal sealing arrangement <NUM>. Generally, this arrangement <NUM> has two main functions; <NUM>) providing the transversal sealing, i.e. welding two opposite sides of the tube together such that the product in a lower part of the tube, placed downward the sealing arrangement, is separated from the product in the tube placed upward the sealing arrangement, and <NUM>) cutting off the lower part of the tube such that the package <NUM> is formed. Alternatively, instead of providing the transversal sealing and cutting off the lower part in one and the same arrangement <NUM> as illustrated, the step of cutting off the lower part may be made in a subsequent step by a different piece of equipment, or by the consumer if the packages are intended to be sold in a multi-pack.

To provide for that the food product FP is hindered from coming in contact with a raw edge of the packaging material PM, a protective strip <NUM> may be applied onto to the web <NUM> as illustrated in <FIG>. One way of providing for that the protective strip <NUM> and the web <NUM> can be attached to each other is to heat these by using an induction heating device <NUM>. By heating the protective strip <NUM> and the web <NUM>, the with a counter-pressure roller <NUM> can be used for pressing the web <NUM> and the protective strip <NUM> together such that the web <NUM> and the strip <NUM> adhere to one another.

As illustrated in <FIG>, once the protective strip <NUM> is attached to the web <NUM>, a first longitudinal edge section <NUM> of the web <NUM> can be covered by a first longitudinal section <NUM> of the protective strip <NUM>. The web <NUM> and the protective strip <NUM> can be attached to each other in that an outside surface <NUM> of the protective strip <NUM> in the first longitudinal section <NUM> is attached to an inside surface <NUM> of the web <NUM> in the first longitudinal edge section <NUM>.

When the tube <NUM> is formed in the longitudinal sealing arrangement <NUM>, the web <NUM>, which may comprise an inner protective layer <NUM>, an outer protective layer <NUM> and a cellulose-based mid-layer <NUM>, can be folded such that the first longitudinal edge section <NUM> of the web <NUM> is placed inside a second longitudinal edge section <NUM> of the web <NUM>, i.e. placed radially inwards, as illustrated by way of example in <FIG>. To provide the longitudinal sealing, an outside surface <NUM> of the first longitudinal edge section <NUM> can be attached to an inside surface <NUM> of the second longitudinal section <NUM> of the web <NUM>. This attachment may be achieved by heating the two sections and by providing a pressure by using a pair of rollers similar to those illustrated in <FIG>.

In the longitudinal sealing arrangement <NUM>, a second longitudinal edge section <NUM> of the strip <NUM> can be attached to the web <NUM> such the food product FP is hindered from coming into contact with the cellulose-based mid-layer <NUM>. More particularly, an inside surface <NUM> of the second longitudinal edge section <NUM> of the strip <NUM> can be attached to an outside surface <NUM> of a mid-section <NUM> of the web <NUM>, wherein the mid-section <NUM> is placed between the first and second longitudinal edge sections <NUM>, <NUM> of the web <NUM>.

In addition to the outer protective layer <NUM>, which may be a polymer-based layer arranged to protect the cellulose-based mid-layer <NUM> from e.g. moisture, and the inner protective layer <NUM>, which also may be a polymer-based layer, but arranged to protect the mid-layer <NUM> from the food product FP, the packaging material PM may comprise a barrier layer <NUM>. A barrier layer may be an Aluminum foil, but it may also be e.g. a polymer-based layer and/or a barrier-coated film. A barrier layer <NUM>, or a combination of such layers, serves for that oxygen is hindered from reaching the food product FP held in the packages <NUM>.

As illustrated in <FIG>, in the transversal sealing sections <NUM>, the tube <NUM> can be pressed together such that the protective strip <NUM> is also forming part of the transversal sealing sections <NUM>.

A problem that may arise when using induction heating, as illustrated in <FIG>, for adhering the strip <NUM> to the web <NUM> is that the packaging material PM is negatively affected. For instance, as illustrated in <FIG> by way of example, generating excessive heat during strip application may result in delamination, that is, the different layers of the packaging material PM release from each other or that one of the layers, e.g. the cellulose-based mid-layer <NUM>, is transformed into several layers. In the <FIG>, examples of delamination is pointed to by white arrows.

Another unwanted affect that may be arise in the packaging material PM during the strip application process is that blisters are formed, pointed to by striped arrows in <FIG>. It has been found that this phenomena is of particular relevance when the cellulose-based mid-layer <NUM> is a carton layer or similar type of layer in which moisture can be present. When heat is added, the presence of moisture may result in that the blisters are formed.

The problem with the delamination and the blisters are that the packaging material PM is weakened and that food protecting properties of this may be deteriorate once the strip <NUM> has been applied. This may be less of a problem if the layers of the packaging material PM are even more deteriorated by e.g. the transversal sealing process performed in the transversal sealing arrangement <NUM>, but as more efficient and well-controlled processes are provided in e.g. the transversal sealing arrangement <NUM> it has been found that the effects of the packaging material PM caused by the strip application also should be considered and taken into account for.

<FIG> illustrates a simplified model on how blisters and pin-holes, may be formed. Generally, if pressure P is held below a pressure threshold P' and temperature T is held below a temperature threshold T', no or at least few blisters and pinholes are formed. The thresholds P', T' can be determined by gauge pressure <NUM> and load bearing capacity of a polymer used for the strip <NUM>.

To reduce any negative effects on the packaging material PM that may be caused as an effect of the strip application process, it has been found that an air heating arrangement <NUM> as generally illustrated in <FIG> can be used. Unlike present systems for strip application, the heating arrangement <NUM> provides individual heating of the strip <NUM> and the web <NUM>. As illustrated, a first nozzle <NUM> may be used for providing a first flow <NUM> of heated air onto the web <NUM>, and a second nozzle <NUM> may be used for providing a second flow <NUM> of heated air onto the strip <NUM>.

By having individual temperatures, T1 for the first flow <NUM> and T2 for the second flow <NUM>, it is made possible to provide sufficient heating for achieving melting of strip <NUM> and the web <NUM>, respectively, such that the two can be adhered together reliably, at the same time as the risk of overheating, thereby causing blisters and delamination, can be held low. In addition to individually set the first and second temperatures T1, T2, also a first and a second volume flow rate VFR1, VFR2, may be set individually. Thus, instead of having different temperatures, it may be possible to achieve different heating by having different volume flow rates.

Even though not illustrated, by measuring humidity, temperature and/or pressure in surrounding air <NUM>, this may be taken into account when setting the first and second temperatures T1, T2 and/or the first and second volume flow rates VFR1, VFR2.

As illustrated, the first flow <NUM> may be directed in a first flow direction FD1 and the second flow <NUM> may be directed in a second flow direction FD2. By having these directions diverted <NUM> degrees or more, it is made possible to reduce a risk that the web <NUM> is heated by the second flow <NUM> or a risk that the strip <NUM> is heated by the first flow <NUM>, thereby ensuring adequate individual heating of the two.

<FIG> and <FIG> illustrate an example of the air heating arrangement <NUM> that can be attached to an existing apparatus <NUM>. By applying this air heating arrangement <NUM> directly upstream a PM reel holder easily accessible on one side of the apparatus <NUM>, the strip <NUM> and the web <NUM> may be heated and adhered to each other before the web <NUM> is fed into the apparatus <NUM> and thereby not easily accessible.

A mounting bracket <NUM> can be provided such that the air heating arrangement <NUM> can easily be attached to the packaging machine <NUM>. An advantage of having the air heating arrangement <NUM> placed on an outside of the packaging machine <NUM> and having the mounting bracket <NUM>, or other similar arrangement for providing easy installation, is that upgrading of existing filling machines is facilitated. An additional advantage of having the air heating arrangement <NUM> placed on the outside of the packaging machine <NUM> is that heating of the protective strip <NUM> and the web <NUM> can be monitored by an operator easily.

<FIG> illustrates, also by way of example, the air heating arrangement <NUM>, illustrated by way of example in <FIG> and <FIG>, as well as parts of the packaging machine <NUM> arranged for feeding and directing the protective strip <NUM> such that this can be exposed to the heat via the second flow <NUM> from the second nozzle <NUM>.

<FIG> is a flowchart illustrating a method <NUM> for producing packages <NUM> holding food product by way of example.

In a first step <NUM>, the web <NUM> can be provided, and in a second step <NUM>, the protective strip <NUM> can be provided.

In a third step <NUM>, the first longitudinal edge section <NUM> of the inside surface <NUM> of the web <NUM> can be heated by applying the first flow <NUM> of heated air via the first nozzle <NUM>.

In a fourth step <NUM>, the first longitudinal edge section <NUM> of the inside surface <NUM> of the protective strip <NUM> can be heated by applying the second flow <NUM> of heated air via the second nozzle <NUM>.

In a fifth step <NUM>, the outside surface <NUM> of the first longitudinal edge section <NUM> of the protective strip <NUM> can be attached onto the inside surface <NUM> of the first longitudinal edge section <NUM> of the web <NUM>.

In a sixth step <NUM>, the tube <NUM> can be formed from the web <NUM> of packaging material (PM) by directing the first longitudinal edge section <NUM> of the web <NUM> inside the second longitudinal edge section <NUM> of the web <NUM>.

In a seventh step <NUM>, the outside surface <NUM> of the first longitudinal edge section <NUM> can be attached onto the inside surface <NUM> of the second longitudinal edge section <NUM>.

In an eighth step <NUM>, the inside surface <NUM> of the second longitudinal section <NUM> of the protective strip <NUM> can be attached onto the outside surface <NUM> of the mid-section <NUM> of the web <NUM>, wherein the mid-section <NUM> can be placed between the first and second edge sections <NUM>, <NUM>, thereby providing for that the food product (FP) can be hindered from coming into contact with the cellulose-based mid-layer <NUM> of the packaging material (PM).

In a ninth step <NUM>, the food product (FP) can be filled into the tube <NUM>.

In a tenth step <NUM>, the tube <NUM> can be transversally sealed in transversal sealing sections <NUM> in a lower end of the tube <NUM>.

In an eleventh step <NUM>, the tube <NUM> can be cut in the transversal sealing sections <NUM> such that the packages <NUM> are formed.

Even though described in a particular order, the different steps may also be performed in other orders and also some of the steps may be performed in parallel, e.g. the web and the protective strip may be heated in parallel.

<FIG> generally illustrates an apparatus <NUM> for producing packages <NUM> holding food product FP. The apparatus can comprise a web holder <NUM> arranged to hold the web <NUM> of packaging material PM comprising at least the outer protective layer <NUM>, the cellulose-based mid-layer <NUM> and the inner protective layer <NUM>. Further, the apparatus may comprise a protective strip holder <NUM> arranged to hold a protective strip (<NUM>). The apparatus <NUM> may further comprise the air heating arrangement <NUM>, illustrated by way of example in <FIG>, <FIG> and <FIG>, comprising the first nozzle <NUM> and the second nozzle <NUM>, wherein the first nozzle <NUM> can be arranged to heat the first longitudinal edge section <NUM> of the inside surface <NUM> of the web <NUM> by applying the first flow <NUM> of heated air, and the second nozzle <NUM> can be arranged to heat the first longitudinal edge section <NUM> of the outside surface <NUM> of the protective strip <NUM> by applying the second flow <NUM> of heated air via the second nozzle <NUM>. Still further, it may be provided a first strip application arrangement <NUM> arranged to attach the outside surface <NUM> of the first longitudinal edge section <NUM> of the protective strip <NUM> onto the inside surface <NUM> of the first longitudinal edge section <NUM> of the web <NUM>. A tube forming arrangement <NUM> may be arranged to form the tube <NUM> of the web <NUM> of packaging material PM by directing the first longitudinal edge section <NUM> inside the second longitudinal edge section <NUM> of the web <NUM>. The apparatus may also comprise the longitudinal sealing arrangement <NUM> arranged to seal the web <NUM> longitudinally by attaching the outside surface <NUM> of the first longitudinal edge section <NUM> onto the inside surface <NUM> of the second longitudinal edge section <NUM>. In addition, it may be provided a second strip application arrangement <NUM> arranged to attach the inside surface <NUM> of the second longitudinal edge section <NUM> of the protective strip <NUM> onto the outside surface <NUM> of the mid-section <NUM> of the web <NUM>, wherein the mid-section <NUM> is placed between the first and second edge sections <NUM>, <NUM>, thereby providing for that the food product FP is restrained, or hindered, from coming into contact with the cellulose-based mid-layer <NUM> of the packaging material PM. In addition, the food product pipe <NUM> may be arranged to fill the food product FP into the tube <NUM>, and also the apparatus <NUM> can comprise the transversal sealing arrangement <NUM> arranged to seal the tube <NUM> transversally in transversal sealing sections <NUM> in the lower end of the tube <NUM>, and to cut the tube <NUM> in the transversal sealing sections <NUM> such that the packages <NUM> are formed.

<FIG> is a flowchart illustrating a method <NUM> for preparing the web <NUM> of packaging material PM and a protective strip <NUM> before attaching these to each other. In a first step <NUM>, protective strip material data can be received. In a second step <NUM>, a first temperature T1 and/or a first volumetric flow rate VFR1 based on the protective strip material data can be determined. In a third step <NUM>, the air heating arrangement <NUM> can be controlled to expose the protective strip <NUM> to the first flow <NUM> of heated air via the first nozzle <NUM>, wherein the first flow <NUM> has the first temperature T1 and/or the first volumetric flow rate VFR1. In a fourth step <NUM>, packaging material data can be received. In a fifth step <NUM>, a second temperature T2 and/or a second volumetric flow rate VFR2 can be determined based on the packaging material data. In a sixth step <NUM>, the air heating arrangement <NUM> can be controlled to expose the web <NUM> to the second flow <NUM> of heated air via the second nozzle <NUM>, wherein the second flow <NUM> has the second temperature T2 and/or the second volumetric flow rate VFR2.

Claim 1:
A method (<NUM>) for producing packages (<NUM>) holding a food product (FP), said method (<NUM>) comprising
providing (<NUM>) a web (<NUM>) of packaging material (PM) comprising at least an outer protective layer (<NUM>), a cellulose-based mid-layer (<NUM>) and an inner protective layer (<NUM>),
providing (<NUM>) a protective strip (<NUM>),
heating (<NUM>) a first longitudinal edge section (<NUM>) of an inside surface (<NUM>) of the web (<NUM>) by applying a first flow (<NUM>) of heated air via a first nozzle (<NUM>),
heating (<NUM>) a first longitudinal edge section (<NUM>) of an inside surface (<NUM>) of the protective strip (<NUM>) by applying a second flow (<NUM>) of heated air via a second nozzle (<NUM>),
attaching (<NUM>) the outside surface (<NUM>) of the first longitudinal edge section (<NUM>) of the protective strip (<NUM>) onto the inside surface (<NUM>) of the first longitudinal edge section (<NUM>) of the web (<NUM>),
forming (<NUM>) a tube (<NUM>) of the web (<NUM>) of packaging material (PM) by directing the first longitudinal edge section (<NUM>) of the web (<NUM>) inside a second longitudinal edge section (<NUM>) of the web (<NUM>),
attaching (<NUM>) an outside surface (<NUM>) of the first longitudinal edge section (<NUM>) onto an inside surface (<NUM>) of the second longitudinal edge section (<NUM>),
attaching (<NUM>) an inside surface (<NUM>) of a second longitudinal section (<NUM>) of the protective strip (<NUM>) onto an outside surface (<NUM>) of a mid-section (<NUM>) of the web (<NUM>), wherein the mid-section (<NUM>) is placed between the first and second edge sections (<NUM>, <NUM>), thereby providing for that the food product (FP) is hindered from coming into contact with the cellulose-based mid-layer (<NUM>) of the packaging material (PM),
filling (<NUM>) the food product (FP) into the tube (<NUM>),
sealing (<NUM>) the tube (<NUM>) transversally in transversal sealing sections (<NUM>) in a lower end of the tube (<NUM>), and
cutting (<NUM>) the tube (<NUM>) in the transversal sealing sections (<NUM>) such that the packages (<NUM>) are formed characterized in that the first flow (<NUM>) of heated air has a first temperature (T1), and the second flow (<NUM>) of heated air has a second temperature (T2), wherein the first temperature (T1) is adjusted in accordance with properties of the packaging material (PM), and the second temperature (T2) is adjusted in accordance with properties of the protective strip (<NUM>).