Patent Description:
In the food packaging field, plastic films are used to form packages. The plastic film wraps and protects the product also allowing the consumer to see the product and thus visually assess product features such as size, shape, and quality of the product. Plastic packages used in the packaging of food often include containers in the form of a bag or pouch of plastic material into which the product, such as a food product, is inserted. The plastic container is then sealed.

In the above context, heat shrinkable plastic film materials have been widely used for their ability to provide a resistant enclosure for the product, while typically reducing the quantity of plastic material necessary to form the package and thus reducing waste material when the package needs to be disposed of after aperture.

On the other hand, known packaging processes and systems used to wrap products using heat shrinkable plastic film material often form packages of scarce aesthetic properties and/or not susceptible of receiving prints.

Furthermore, known processes and systems using heat shrinkable material are often complex to implement and require additional operations, such as piercing and then sealing of the processed package, in order to evacuate gas possibly contained in the package during shrink.

Moreover, known shrink techniques are often using water to shrink packages, which inherently requires very complex and cumbersome apparatus.

In addition, known shrink apparatus and processes are unable to shrink selected portions of the processed packages.

Additionally, known systems and processes, particularly those using shrinkable plastic wraps, do not provide efficient solutions for forming easy opening features on the package, thus resulting either in complex solutions or in the production of packages, which may be difficult to open.

Finally, known systems and processes, particularly those using shrinkable plastic wraps, do not provide efficient solutions for automatizing the application of labels to the package. Document <CIT> discloses a bag sealer with a composite belt assembly comprising a pair of belts forming a gap where the bag neck of a package to be sealed is received.

The object of the present invention is to solve the one or more of the drawbacks and/or limitations of the above prior art. Auxiliary objects of the invention are indicated below.

An object of the invention is to provide a new heat shrink apparatus and/or a new heat shrink device and related process of simplified design, which may be used to efficiently shrink the film of the packages under formation, such as bags or pouches or other containers.

A further object of the invention is to provide a new heat shrink apparatus and/or a new heat shrink device and/or a new heat shrink process capable of efficiently shrinking the packages under formation, avoiding the need of supplementary operations such as piercing of the film.

Another object is that of providing a new heat shrink apparatus and/or a new heat shrink device and/or a new hat shrink process adapted to treat and heat shrink selected portions of a given package.

An additional object of the invention is that of rendering available a new heat shrink apparatus and/or a new heat shrink device and/or a new heat shrink process capable of efficiently evacuate at least part of the gas from inside the processed container.

A further object of the invention is to provide a new heat shrink apparatus and/or a new heat shrink device and/or a new heat shrink process which may be combined with an apparatus/process for vacuumizing the packages under formation, resulting a lean packaging line.

Another object of the invention is a packaging line and a packaging process implementing the new shrink apparatus and/or the new heat shrink device and process in an efficient manner.

Furthermore, it is an object offering a packaging line and process which may be able to form packages, for example in the form of a plastic bag or pouch, using a reduced quantity of plastic, yet guaranteeing and efficient and robust packaging.

Another object of the invention is a packaging line and process able to form packages of simple and cost-effective structure.

An additional object is that of offering is a packaging line and process able to form packages of improved aesthetic properties and provided with substantially smooth surfaces suitable for carrying prints, drawings, images and the like.

Furthermore, an ancillary object is that of offering a packaging line and process where application of labels is facilitated and automatized.

Finally, a further ancillary object is that of offering a packaging line and process configured for forming an easy opening feature on the package.

A heat shrink device according to the invention is disclosed in any one of claims <NUM>-<NUM>.

A process of heat shrinking according to the invention is disclosed in any one of claims <NUM>-<NUM>.

A packaging line according to the invention is disclosed in any one of claims <NUM>-<NUM>.

A packaging process according to the invention is disclosed in any one of claims <NUM>-<NUM>.

Some embodiments and some aspects of the invention are described hereinafter with reference to the accompanying drawings, provided only for illustrative and, therefore, nonlimiting purposes, in which:.

It should be noted that in the present detailed description, corresponding parts illustrated in the various figures are indicated by the same reference numerals. The figures may illustrate the object of the invention by representations that are not in scale; therefore, parts and components illustrated in the figures relating to the object of the invention may relate solely to schematic representations.

The terms upstream and downstream refer to a direction of advancement of the containers or packages being processed along a predetermined operating path.

The term product P means an article or a composite of articles of any kind. For example, the product may be of a foodstuff type and be in solid, liquid or gel form, i.e. in the form of two or more of the aforementioned aggregation states. In the food sector, the product may comprise: meat, fish, cheese, treated meats, prepared and frozen meals of various kinds.

The heat shrink apparatus, the heat shrink device and the packaging line described herein include at least one control unit <NUM> designed to control part or all the steps of the processes herein described and claimed for making the package. The control unit may be only one or be formed by a plurality of different control units, for example at least one associated to apparatus <NUM>, at least one associated to device <NUM> and at least one governing controller for the line <NUM>. Of course, different configurations may be envisaged according to the design choices and the operational needs. The term control unit means an electronic component which may comprise at least one of: a digital processor (for example comprising at least one selected from the group of: CPU, GPU, GPGPU), a memory (or memories), an analog circuit, or a combination of one or more digital processing units with one or more analog circuits. The control unit can be "configured" or "programmed" to perform some steps: this can be done in practice by any means that allows configuring or programming the control unit. For example, in the case of a control unit comprising one or more CPUs and one or more memories, one or more programs can be stored in appropriate memory banks connected to the CPU or to the CPUs; the program or programs contain instructions which, when executed by the CPU or the CPUs, program or configure the control unit to perform the operations described in relation to the control unit. Alternatively, if the control unit is or includes analog circuitry, then the control unit circuit may be designed to include circuitry configured, in use, for processing electrical signals so as to perform the steps related to control unit. The control unit may comprise one or more digital units, for example of the microprocessor type, or one or more analog units, or a suitable combination of digital and analog units; the control unit can be configured for coordinating all the actions necessary for executing an instruction and instruction sets.

The film used for forming the containers (e.g., bags or pouches) and packages of the invention is made of plastic material, in particular polymeric material; the film is for example a flexible mono or multilayer material comprising at least an outer heat-weldable layer. In case of a multilayer film, the film may include an optional gas barrier layer and a one or more protective layers.

The film, in a currently preferred option, is a heat-shrinkable plastic film showing a free shrinking value at <NUM> (value measured in accordance with ASTM D2732, in oil) in the range from <NUM>% to <NUM>%, optionally from <NUM>% to <NUM>%, in particular from <NUM>% to <NUM>%, in both longitudinal and transverse directions. As used herein the terminology "heat-shrinkable," "heat-shrink," and the like, refer to the tendency of film to shrink upon the application of heat, such that the size of the film decreases while the film is in an unrestrained state. The plastic film material has preferably thickness comprised between <NUM> and <NUM>, optionally between <NUM> and <NUM>. In one example, the plastic film material has thickness comprised between <NUM> and <NUM> and is heat-shrinkable showing the free shrinking value indicated above.

Although, any plastic film with the above thickness, optionally made in shrinkable material with the above shrink properties would be adequate to implement the claimed invention, suitable exemplifying materials are disclosed in the publications:
<CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>.

In <FIG> and <FIG> a heat shrink apparatus is indicated with reference number <NUM>. The heat shrink apparatus <NUM> is adapted to process containers <NUM> having a main portion <NUM> where a product P is housed, a terminal portion <NUM> having at least one aperture 102a (in particular a terminal open mouth - see <FIG>) allowing gas evacuation from the container, and an intermediate portion <NUM> connecting the main portion and the terminal portion. The containers disclosed herein are of the type made from or comprising heat shrinkable plastic film: in particular the containers <NUM> may be bags or pouches entirely made for heat shrinkable plastic film material. For example the containers are bags or pouches made from heat shrinkable plastic film, wherein the heat shrinkable plastic film used for making each container shows a free shrinking value at <NUM> (value measured in accordance with ASTM D2732, in oil) in the range from <NUM>% to <NUM>% in both longitudinal and transverse directions. In accordance with a currently preferred variant the heat shrinkable plastic film used for making each container shows a free shrinking value at <NUM> (value measured in accordance with ASTM D2732, in oil) in the range from <NUM>% to <NUM>% in both longitudinal and transverse directions or in the range from <NUM>% to <NUM>% in both longitudinal and transverse directions.

The shrink apparatus <NUM> comprises an inlet <NUM> for receiving containers to be processed and an outlet <NUM> for delivering processed containers. A heat treatment zone <NUM> (see <FIG>) is defined between the inlet and the outlet: the heat treatment zone <NUM> is configured to heat shrink the main portion <NUM> of processed containers. In practice, the heat treatment zone <NUM> only receives the main portion <NUM> of the processed containers <NUM> and is configured to direct heat basically only onto the containers main portion. At this purpose, the heat shrink apparatus <NUM> comprises a heat protected zone <NUM> extending adjacent to the heat treatment zone <NUM> and configured for receiving the terminal portion <NUM> of each container and for protecting the terminal portion from heat coming from the heat treatment zone <NUM>, such that the terminal portion <NUM> of each container <NUM> is not heat shrunk or at most minimally heat shrunk to an extent largely inferior to the heat shrinking applied to the main portion <NUM>.

In other words, the heat shrink apparatus <NUM> is a capable of selectively heat shrinking only or substantially only the main portion <NUM> of each processed container.

The heat protected zone <NUM> is connected to the heat treatment zone <NUM> via one or more openings <NUM> (see <FIG>) extending between the heat treatment zone <NUM> and the heat protected zone <NUM>: in this way, each of the processed containers <NUM> may have the respective main portion <NUM> travelling in the heat treatment zone <NUM>, the respective intermediate portion <NUM> crossing the mentioned one or more openings <NUM>, while the terminal portion <NUM> remains protected by and travels inside the heat protected zone <NUM>.

Note that depending upon the variants, the one or more openings <NUM> may comprise a single longitudinal opening extending along to the entire heat treatment zone and positioned between the heat treatment zone <NUM> and the heat protected zone <NUM>: the single longitudinal opening may for example be in the form of a longitudinal slit or of a thin and elongated opening configured for receiving at least the intermediate portion of each processed container, such that, during operation of the heat shrink apparatus, the main portion <NUM> of each processed container <NUM> is received in the heat treatment zone <NUM>, while the terminal portion <NUM> of each processed container remains outside the heat treatment zone <NUM> with the intermediate portion of each container passing through the longitudinal opening <NUM>.

In an alternative variant, the apparatus may present a plurality of discrete openings <NUM> formed along the heat treatment zone and each configured for receiving the intermediate portion <NUM> of a respective processed container <NUM>, such that, during operation of the heat shrink apparatus, the main portion <NUM> of each processed container is received in the heat treatment zone <NUM>, while the terminal portion <NUM> of each processed container remains outside the heat treatment zone with the intermediate portion of each container passing through a respective discrete opening <NUM>.

In order to properly support the processed containers <NUM> during heat treatment, the heat treatment zone <NUM> also comprises a support structure <NUM> configured for supporting the main portion <NUM> of each processed container during motion from the inlet <NUM> to the outlet <NUM> of the heat shrink apparatus <NUM>. The support structure <NUM> may for example be formed by a plurality of adjacent rollers <NUM> (for example idle rollers with axis of rotation orthogonal to the direction of movement of the containers in the zone <NUM>) positioned at intervals along the heat treatment zone and displaceable along a closed path, which comprises a top segment extending from said inlet <NUM> to said outlet <NUM>, by a chain mechanism <NUM> operative at each end of the rollers <NUM>, as shown in <FIG>. Alternatively, the support structure <NUM> may comprise idle rollers and driven rollers positioned at intervals along the heat treatment zone or all driven rollers. Of course other alternative designs (not shown) of the support structure <NUM> may be contemplated such as a simple sliding plane extending along the heat treatment zone, or a conveyor belt extending along the heat treatment zone and actively driving the main portions of the processed containers. In case driven means are used such as one or more driven rollers or one or more conveyor belts, these driven means are controlled by the control unit <NUM> and synchronized with the motion of the pair of belts acting on the intermediate portion of the processed packages (as it will be further explained below).

In accordance with an aspect, the apparatus <NUM> is configured to keep the heat treatment zone <NUM> at a shrink temperature sufficiently high to heat shrink the material of the film used to form the containers <NUM>, while at the same time keeping the heat protected zone <NUM> at a temperature sufficiently below the film shrink temperature: for example in a currently preferred option the apparatus <NUM> is configured for keeping the heat protected zone at a temperature at least <NUM>° C below said shrink temperature, optionally at a temperature at least <NUM>° below the shrink temperature.

In greater detail, the heat treatment zone <NUM> comprises at least one heater <NUM> which, during operation of the apparatus, is configured to maintain the heat treatment zone at a/the shrink temperature, which is above <NUM>° C, optionally comprised between <NUM>° and <NUM>° C, more optionally in a range of <NUM>° ± <NUM>. The temperature range maintained in the heat treatment zone <NUM> depends upon the material of the film used for the containers <NUM> and may be set by a user acting on a user interface <NUM> associated to a control unit <NUM> operatively connected to and controlling the one or more heaters <NUM>. In the example shown, the apparatus and specifically the heat treatment zone comprises a plurality of independently controllable heaters <NUM> (for example controllable by said control unit <NUM>): in a possible implementation <NUM> to <NUM> or even more independently controllable heaters <NUM> may be used, distributed along longitudinal development of the heat treatment zone <NUM>, as shown in <FIG>, thereby defining a corresponding plurality of independently heat controllable consecutive longitudinal sections 4a of the heat treatment zone <NUM>. In the example shown, the heat treatment zone also has one or more temperature sensors <NUM>, distributed along the heat treatment zone: the control unit <NUM> is communicatively connected with the one or more temperature sensors <NUM> and with the heater or heaters <NUM>. In detail, the control unit <NUM> is configured to:.

In particular, the control unit <NUM> is configured to control the heater or heaters <NUM> based on said one or more temperature signals and on one or more reference values in order to maintain the temperature of the heat treatment zone within a set temperature above <NUM>° C, optionally comprised between <NUM>° and <NUM>° C, more optionally in a range of <NUM>° ± <NUM>.

From a structural point of view, each one of the heaters <NUM> comprises a heating source 7a (for example an electric resistor or a IR heating source or other) and one or more fans 7b configured to blow on the heating source and direct hot hair in the heat treatment zone, for example via appropriate channels leading to nozzles 7c which are distributed on a top portion and on one or more sides of the heat treatment zone <NUM>, as shown in <FIG>, to thereby direct hot air towards the processed containers both from above and from one or more sides. In accordance with one additional aspect the support structure <NUM> described above has through apertures or passages <NUM> at intervals (in case the support surface is formed by rollers this is evident, but also in case the support surface is defined by a conveyor or by a sliding plane a plurality of through apertures may be distributed all along the support surface) for hot air coming from the heater <NUM>, which is conveniently located below the support structure <NUM>, and configured to direct air towards the processed containers also from below the support structure such that hot air may impinge also on the inferior side of the processed containers. In this way, the heat treatment zone is uniformly a heated and the containers main portions <NUM> uniformly treated with hot air, thus performing an efficient heat shrinking with the heated air without use of any liquid.

As to the heat protected zone <NUM>, the apparatus <NUM> is configured during operation (i.e., while the containers <NUM> are processed and the main portions thereof heat treated and shrunk in the heat treatment zone <NUM>) to keep the heat protected zone <NUM> at a temperature below <NUM>° C, in particular below <NUM>° C.

In order to protect the heat protected zone <NUM> from heat generated in the heat treatment zone, one or more heat insulators <NUM> delimit the heat treatment zone <NUM> and are in particular in the form of one or more heat insulating walls positioned at the periphery of the heat treatment zone. The heat insulators <NUM> include at least one heat insulating wall or diaphragm <NUM> just interposed between the heat protected zone <NUM> and the heat treatment zone and delimiting the opening(s) <NUM>. As shown in <FIG>, there may be two adjacent heat insulating walls or diaphragms <NUM> located at the opening(s) <NUM> on opposite sides of the same opening(s). The heat protected zone <NUM> of the enclosed example also comprises a cooling structure <NUM> defining an elongated seat <NUM> (<FIG>), which may for example be in the form of an elongated flat channel, configured for receiving the terminal portions <NUM> of each processed container: the seat <NUM> has a proximal side 12a ending at said one or more longitudinal openings <NUM> in order to receive the containers terminal portions. In the example shown, the mentioned heat insulating wall <NUM> is interposed between the side of the cooling structure <NUM> proximal to the heat treatment zone <NUM> and the same heat treatment zone <NUM>, such that on the one side the wall <NUM> provides an insulating effect and on the other the cooling structure further acts in cooling the received terminal portions <NUM>. The cooling structure <NUM> may be formed by one or more longitudinally extending bodies made in heat conductive material (such as metal, in particular Aluminum) and may be provided with heat dissipating features such as protruding cooling fins. As shown in <FIG> and <FIG>, the heat protected zone comprises at least one active cooler <NUM> which, during operation of the apparatus <NUM>, is configured to act on the cooling structure <NUM> to keep the elongated seat <NUM> of the heat protected zone at a temperature at least <NUM>° C below said shrink temperature, more optionally at a temperature at least <NUM>° below the shrink temperature. For example the heat protecting structure <NUM> may have a plurality of coolers, for example from <NUM> to <NUM> coolers, distributed along the heat protected zone and independently controllable by the control unit <NUM>.

Each cooler <NUM> may be configured to cool at least cooling structure described above and may at this purpose comprises a cooling fan 13a configured to blow cold air towards cooling structure <NUM> and/or a liquid cooling system having a source of cold liquid (not shown) and an associated cold liquid circuit 13b circulating cold liquid inside or adjacent to cooling structure <NUM> via appropriate pipes or channels.

In accordance with a further aspect, the heat protected zone may further include one or more auxiliary temperature sensors <NUM> operative at the heat protected zone: in this case the control unit <NUM> would be communicatively connected with the one or more auxiliary temperature sensors <NUM> and with the active cooler or coolers <NUM> and would be configured to:.

In the example of the attached figures the shrink apparatus <NUM> comprises a tunnel <NUM> delimiting or containing the heat treatment zone (the tunnel <NUM> being preferably formed from wall(s) <NUM> in insulating material) and optionally the heat protected zone <NUM>: as it is visible the longitudinal opening(s) is for example defined at a longitudinal side portion of the tunnel facing the heat protected zone <NUM>. On its turn, the heat protected zone is positioned adjacent the one or more longitudinal openings and may extend on a side of said tunnel. In a currently preferred variant all walls of the tunnel are made from heat insulating material. The above described longitudinal opening <NUM> is for example in the form of a longitudinal slit, in particular of a longitudinal and rectilinear slit, through the wall <NUM> which extends in the tunnel and extends from the inlet to the outlet of the heat shrink apparatus and which separates the heat treatment zone from the heat protected zone.

Note that although in the example herein described, the heat treatment zone and the heat protected zone extend horizontally, nothing excludes the heat shrink apparatus <NUM> and thus the heat treatment zone <NUM> and the heat protected zone <NUM> be inclined or vertical, with the containers thus moving from inlet to outlet along a non-horizontal path.

In accordance with a further aspect, a pair of opposed belts <NUM> having mutually facing rectilinear belt stretches 17a operate in correspondence of said opening(s) <NUM>. In practice, the opening or openings <NUM> may be formed on the wall <NUM> interposed between the heat treatment zone and the heat protected zone and the two belts <NUM> may be placed immediately adjacent to said opening(s) <NUM> and said wall <NUM>, or alternatively the openings may directly be defined by the mutually facing belt stretches of the two cooperating and opposed belts <NUM>. As it is visible from <FIG>, the two opposed belts are endless belts engaged to respective two or more pulleys <NUM> at least one of which is a driven pulley.

Each pair of opposed belts is designed according one the following alternatives:.

In all the above variants, the apparatus <NUM> may include a regulator for adjusting the size, in particular the thickness, of the one or more longitudinal openings <NUM>. In a possible option, there may also be a further regulator operative on one or both the belts of each pair of opposed belts to adjust the size of the gap or the entity of pressure between mutually facing stretches of the two belts forming each pair of belts.

In this way it is possible to adapt the size of the opening(s) and/or of the gap between the belts to the specific containers treated and thus to the actual thickness of the film used, thereby adjusting the resistance offered by the terminal portions of each contained to air/gas passage. This may be advantageous to obtain during heat treatment in the heat treatment zone an initial bubbling of the main portion which may initially expand due to expansion of the gas contained therein (as gas inside the heat treatment zone but outside the containers may easily escape to the outside environment at least given the presence of the inlet and outlet apertures of the apparatus) and due to the resistance offered to air passage by the terminal portions of each container and then when the shrink effect and related forces increase the main portion significantly contracts expelling a major portion of gas contained in the containers main portions.

Another aspect concerns a process of heat shrinking a selected portion of the described containers <NUM>: in particular, the process uses the apparatus <NUM> and allows to heat shrink the main portion <NUM> of each processed container <NUM> without basically heat shrinking the terminal portion <NUM> of the same containers or heat shrinking the terminal portion of each container significantly less than the main portion. During the process the containers <NUM> are fed to the apparatus inlet <NUM>, with the main portion <NUM> of each container received in the heat treatment zone <NUM> and with the terminal portion <NUM> of each container received in the heat protected zone <NUM>. Motion of the containers is continuous at a given speed (greater than zero and preferably constant). Of course a discontinuous step by step movement is not excluded. Motion to the containers may be imparted by the support structure or by driving means operative downstream the apparatus <NUM>.

Thus, the containers are displaced from the inlet <NUM> to the outlet <NUM>: heating and heat shrinking of the main portion <NUM> of each container take place while the main portion travels along the heat treatment zone <NUM> and while the terminal portion <NUM> of each container travels along the heat protected zone <NUM>.

Heat shrinking the main portion <NUM> of each container takes place when the main portion of each container is inside the heat treatment zone <NUM> of the apparatus <NUM> and is at least brought above a shrink temperature causing shrink of the film material forming said main portion. At the same time the terminal portion <NUM> of each container is maintained outside the heat treatment zone and sufficiently insulated from this latter, such that no heat shrinking (or just a minimal heat shrinking significantly less than that on the main portion) occurs to the terminal portion which is constantly maintained at a temperature below the shrink temperature, optionally at a temperature at least <NUM>° C below said shrink temperature, more optionally at a temperature at least <NUM>° below the shrink temperature.

Going in further details, the apparatus <NUM> is controlled such that the heat treatment zone <NUM> is heated to bring the main portion of each container above <NUM>° C, optionally between <NUM>° and <NUM>° C, while at the same time the heat protected zone maintains the respective terminal portion of each container at a temperature below <NUM>° C, in particular below <NUM>° C. As described above, the heater or heaters <NUM> of apparatus <NUM> are activated and the heat treatment zone <NUM> is heated with hot air, which is then delivered onto the main portion <NUM> determining heat shrinking without use of liquid.

During heat shrinking of the main portion <NUM>, the intermediate portion <NUM> of each processed container extends through the one or more openings <NUM> (and if present between the opposite belts <NUM> of apparatus <NUM>) and the terminal portion <NUM> positions inside the cooled structure <NUM> of the heat protected zone <NUM> described above. During heat treatment of the main portion <NUM> of the containers, i.e., while the heat treatment zone <NUM> is heated with hot air, the heat protected zone may be cooled with cooling liquid and/or cooling air active on the mentioned cooled structure <NUM> hosting the terminal portions of the containers.

During heat shrinking of the main portion <NUM> of each container, the main portion contracts and contacts the surface of the product forming a plastic skin on and around the same product and causing air to escape from the inside of the main portion via the intermediate portion <NUM> and out of the container <NUM> via aperture 102a. The one or more openings <NUM> are sized such that, during heating of the main portion <NUM> of each container, initially air inside the main portion expands the main portion (due to the resistance to air passage offered by the intermediate and terminal portions of each container positioned in the opening <NUM> and optionally between belts <NUM>); then heat shrinking generates contracting forces on the film of the main portions <NUM> causing each main portion to contract and contact the surface of the product forming a plastic skin on and around the same product, and also causing air to escape from the inside of the main portion via the intermediate portion and out of the container.

It should be noted that according to a currently preferred option, during heat shrinking of the main portion <NUM> of each container, no vacuum is applied at the terminal portion <NUM> or at the aperture 102a of each container: in other words gas is evacuated from the main portion <NUM> of each container solely by effect of heat shrinking of the same main portion pushing gas out of said aperture <NUM> and with no need of a positive action by a vacuum chamber, or similar vacuum apparatus, operative on the aperture 102a of the terminal portions <NUM>.

In the example shown in the attached figures, the intermediate portion <NUM> of each container is also captured between the mutually opposed rectilinear stretches 17a the described pair of belts <NUM>, which contact the surface of the intermediate portion of each container and compress it without however causing a total occlusion to gas exiting from the main portion of each container via said intermediate portion. The belts may in practice aid in precisely controlling the position of the terminal portions of the processed containers also aiding in driving the containers from the inlet to the outlet, while leaving escape channels 19a open to gas evacuation.

The process and the apparatus <NUM> above described thus allow an efficient gas evacuation from the main portion of the processed packages and also a stretching of the film at the main portion with a consequent positive aesthetical effect as the main portion of the package copies as a skin the contained product an yet remains free or substantially free of wrinkles. Furthermore, as the terminal portion is not heat treated there is no risk of sticking of the internal surfaces of the terminal portion and thus gas can reliably evacuate during the entire process with no need of applying vacuum from the outside of the package.

Another aspect of the invention concerns a heat shrink device <NUM>, shown in detail in <FIG>, for processing the above described containers <NUM> and adapted for heat treatment and specifically for heat shrinking the terminal portions <NUM> not occupied by product of said containers <NUM>. The device <NUM> may be for example used together with the apparatus <NUM> described above and specifically may operate on containers which have already been processed by apparatus <NUM> to heat shrink the terminal portion <NUM> of the containers, which as above discussed is not heat treated by the apparatus <NUM>.

As shown in <FIG>, the device <NUM> comprises a pair of opposed shrink belts <NUM>: each shrink belt <NUM> has an operative stretch 31a facing a corresponding operative stretch of the opposite shrink belt and forming a gap <NUM>. More precisely, the operative stretches 31a have respective external surfaces, which are opposite to each other and define therebetween the mentioned gap <NUM>. The gap extends all along the mutually facing stretches 31a of the belts and is configured for receiving the terminal portion <NUM> of each container <NUM> to be processed.

A belt heater <NUM> is associated to at least one of said shrink belts. In a currently preferred option a belt heater <NUM> is associated to each shrink belt <NUM>. Each belt heater <NUM> configured for bringing the external surface of the operative stretch 31a of the respective belt <NUM> at least at a shrink temperature sufficient to cause heat shrinking of the film forming the terminal portion of the processed packages. In accordance with an aspect, each belt heater <NUM> is configured for bringing the external surface of the operative stretch of the respective belt at a shrink temperature comprised between <NUM>° and <NUM>, such that the terminal portion of each processed container passing through said gap is heat shrunk.

The heat shrink device <NUM> further comprises a flattening body <NUM> associated to one or both shrink belts <NUM> and configured for maintaining flat at least a portion of said external surfaces of the flat stretches. The flattening body <NUM> may be a body in a conductive material, such as a metal and in particular Aluminum, and is positioned downstream the belt heater <NUM> associated to the same belt <NUM>, with respect to a direction of movement A imparted by the opposed shrink belts to the processed containers. Each flattening body <NUM> has a flat active surface 34a acting on the respective operative stretch 31a of the corresponding shrink belt <NUM>.

As shown in the figures, each one of operative stretches 31a is a rectilinear stretch having a respective external surface which is a flat surface and the gap <NUM> is, in an option, a constant thickness planar gap: the thickness of the gap may be comprised between <NUM> and <NUM>, optionally between <NUM> and <NUM>.

Going in further detail, each shrink belt <NUM> is an endless belt engaged between at least a respective driving pulley <NUM> and a respective driven pulley <NUM>: each shrink belt <NUM> is particularly large in width and specifically the width of each shrink belt is comprised between <NUM> and <NUM>, optionally between <NUM> and <NUM> thereby being able to efficiently heat treat terminal portions of relatively big size.

The heater <NUM> associated to each shrink belt is housed inside a loop defined by each respective endless shrink belt <NUM> and configured for heating by direct contact an inside surface of the respective shrink belt and in particular the inside surface of the operative stretch of the respective shrink belt. On its turn, the flattening body <NUM> associated to each shrink belt is also housed inside a loop defined by each respective endless belt and configured for directly contacting an inside surface of the respective shrink belt.

The heat shrink device <NUM> may also comprise a pair of rollers <NUM> operative downstream the opposed shrink belts <NUM> with respect to a direction of movement A imparted by the opposed shrink belts to the processed containers <NUM>: the pair of rollers <NUM> cooperate to define a nip therebetween for receiving the terminal portion <NUM> of each processed container and for further squeezing the terminal portions of the processed containers reducing as possible any wrinkles.

Finally the device <NUM> may include a sealer <NUM> configured to form a heat sealing band on the terminal portion of each processed bag thereby hermetically sealing each processed container. The sealer <NUM> may be separate from the described components (belts and rollers) or it may be associated to one or rollers, for example in the form of a heated circumferential feature on the external surface of one or both the rollers <NUM> (see <FIG>), or to one of the opposed belts optionally in the form of a heated feature on the external surface of one or both the opposed shrink belts. The heated feature on the roller or on the shrink belt may be independently heated to reach a temperature adequate to cause formation of a seal band across the terminal portions of the processed packages. The above components of the device <NUM>, namely the belts and related driving pulleys, the heaters, and the rollers, as well as the sealer, if present, may be controlled by control unit <NUM> or by a dedicated controller of device <NUM>.

A further aspect of the invention concerns a process of heat shrinking a selected portion of above described containers and specifically the terminal portion <NUM> not occupied by product. The process of heat treatment of the terminal portion <NUM> of said containers may be executed using the heat shrink device <NUM> described above and comprises heat shrinking the terminal portion <NUM> of each container: in particular, during heat shrinking of the terminal portion <NUM> of the processed containers <NUM>, the main portion <NUM> of the same containers is not heat shrunk or in any case is heat shrunk significantly less than the terminal portion. In accordance with this process, the terminal portion <NUM> of each processed container is inserted into said gap <NUM> defined by said shrink belts <NUM> of the heat shrink device <NUM> (<FIG>) and heat shrunk while travelling within said gap. At this purpose, each respective belt heater <NUM> associated to each shrink belt is operated for bringing said external surfaces of both the operative stretches 31a at least at a shrink temperature comprised between <NUM>° and <NUM>, such that the terminal portion <NUM> of each processed container passing through said gap <NUM> is also brought to said shrink temperature and thus heat shrunk.

In accordance with an aspect, the terminal portion <NUM> of each container, while travelling through the gap <NUM> between the two shrink belts of device <NUM> is put in contact with and flattened by the external surfaces of the flat stretches 31a, also thanks to the action on the belts of flattening bodies <NUM>. The process may also provide a step of squeezing the terminal portion of each processed container between the above described pair of rollers <NUM> operative downstream the opposed shrink belts <NUM>.

The process may also provide for forming with said shrink belts a heat sealing band on the terminal portion of each processed container thereby hermetically sealing each processed container. Alternatively or in addition the process may provide for forming with said pair of rollers a heat sealing band or a further heat sealing band on the terminal portion of each processed bag thereby hermetically sealing each processed container.

During the above described process and while the terminal portion of each container is brought above the shrink temperature causing heat shrinking of the same terminal portion, the main portion of each container is maintained at a temperature below the shrink temperature, optionally at a temperature at least <NUM>° C below said shrink temperature, more optionally at a temperature at least <NUM>° below the shrink temperature. For example the terminal portion of each container may be brought at a temperature above <NUM>° C, optionally between <NUM>° and <NUM>° C, while the respective main portion is maintained at a temperature below <NUM>° C, in particular below <NUM>° C.

Finally, in accordance with a further aspect the process may provide (typically at the beginning of the process) for a step of adjusting the size of said gap <NUM> before processing said containers in order to adapt the gap to the thickness of the film of the containers being processed.

In <FIG> and <FIG> a respective packaging line <NUM> according to a first and a second example is shown. Each packaging line <NUM> is destined to form a closed and heat shrunk package <NUM> starting from a heat shrinkable film <NUM>. The formed packages <NUM> may be bags or pouches and in particular may be made from heat shrinkable plastic film showing a free shrinking value at <NUM> (value measured in accordance with ASTM D2732, in oil) in the range from <NUM>% to <NUM>% in both longitudinal and transverse directions, optionally in the range from <NUM>% to <NUM>% in both longitudinal and transverse directions, more optionally in the range from <NUM>% to <NUM>% in both longitudinal and transverse directions.

The packaging line <NUM> of <FIG> and <FIG> comprise a loader <NUM> of the containers <NUM>: as already discussed, the containers have a main portion <NUM> where a product P is housed, a terminal portion <NUM> having at least one aperture allowing gas evacuation from the container, and an intermediate portion <NUM> connecting the main portion and the terminal portion. The line <NUM> comprises the heat shrink apparatus <NUM> described above positioned immediately downstream the loader <NUM>; the loader is configured to supply said containers <NUM> to the heat shrink apparatus <NUM>, which is configured to heat shrink the main portion <NUM> of each container, as explained above.

Note that the loader <NUM> is configured to supply said containers <NUM> to the heat shrink apparatus either in form of interconnected containers (as shown in <FIG> and <FIG>) or in form of a sequence of separated containers.

In detail, the loader <NUM> of the line of <FIG> and <FIG> comprises a conveyor <NUM> configured for advancing products P to be packaged along an operating path, and a film supply <NUM> configured for supplying heat shrinkable plastic film <NUM> along the operating path and for positioning the film <NUM> around the products P forming an almost tubular structure <NUM> housing the products P to be packaged. The almost tubular structure <NUM> may be substantially C or U or V shaped in cross section and in any case forms a longitudinal aperture 55a delimited by opposite longitudinal borders of the film <NUM>. In order to obtain the almost tubular structure <NUM> film <NUM> may supplied in the form of a flat film from a film supply <NUM> comprising a feed roll 54a. The flat film <NUM> is bent on itself by a film former or bending device <NUM> to confer to the film the desired almost tubular shape. Of course, nothing excludes that the film be directly supplied in the almost tubular form from an extruder or from other film supplying device or that the film is supplied in tubular form and then opened along a longitudinal line to form an almost tubular film structure.

The loader <NUM> also includes a transverse sealer <NUM> configured for forming seal bands <NUM> transversal to the almost tubular structure <NUM> forming a plurality of the above described containers <NUM>, each of said containers hosting a respective product at the main portion <NUM> and having a terminal portion <NUM> with an aperture, such as with an open end. As mentioned the containers <NUM> may be severed from each other or, as it is currently preferred, supplied as a chain of interconnected open containers to the heat shrink apparatus <NUM> described above. Once the heat shrink apparatus has taken care of heat shrinking the main portion <NUM> of the processed containers <NUM>, the containers exiting from the apparatus <NUM> may be treated by the heat shrink device <NUM>, which is also part of the lines of <FIG> and <FIG>.

In the alternative of <FIG>, the containers <NUM> with the main portion <NUM> heat shrunk exiting from apparatus <NUM> directly reach the heat shrink device <NUM>, which is positioned immediately downstream of the heat shrink apparatus <NUM> and is configured to receive said containers <NUM> with heat shrunk main portions <NUM> and to heat shrink the terminal portions <NUM> of each processed container.

In accordance with a possible variant the heat shrink device <NUM> may also be configured to form a heat seal band across the terminal portion of each processed container (for example perpendicular to seal bands <NUM>) to hermetically close said aperture 102a and form closed packages.

In the variant of <FIG>, the packaging line <NUM> comprises a vacuum station <NUM> configured for receiving the terminal portions <NUM> of the processed containers and to suck gas from each container via said aperture 102a.

In greater detail, the vacuum station <NUM> of the line of <FIG> is positioned immediately downstream of the heat shrink apparatus <NUM> and is configured to receive containers <NUM> with heat shrunk main portions <NUM> coming from the heat shrink apparatus <NUM>.

The vacuum station <NUM> applies to the terminal portions <NUM> of the processed containers a pressure inferior to the pressure present inside the main portions, thereby sucking gas from each container <NUM> via said aperture 102a and vacuumizing the containers <NUM>.

Going into greater detail, and referring to <FIG> and <FIG>, the vacuum station <NUM> of the line of <FIG> is operatively positioned between the heat shrink apparatus <NUM> and the heat shrink device <NUM> and is configured to deliver to the heat shrink device <NUM> vacuumized containers having heat shrunk and vacuumized main portions. The device <NUM> then threats these containers <NUM> and heat shrinks the terminal portions <NUM> thereof as described above.

Note also the vacuum station <NUM> may include a own heat sealer <NUM>, for example comprising heat sealing belts or heat sealing wheels or other heat sealing devices, configured to form a heat seal band across the terminal portion of each processed container to hermetically close said aperture and form closed, and vacuumized, packages.

As shown in <FIG>, the vacuum station <NUM> of the example herein disclosed comprises an elongated vacuum chamber <NUM> having an elongated opening <NUM> extending along the vacuum chamber, a vacuum source <NUM> configured for providing the vacuum chamber <NUM> with an internal vacuum pressure that is lower than an ambient pressure outside the vacuum chamber, and a conveyor <NUM> supporting the main portion of the processed containers <NUM>. In practice the conveyor <NUM> may be a conveyor belt or other type of conveyor and is configured for moving the processed containers <NUM> relative to the vacuum chamber, as shown by arrow B: the containers to be evacuated are positioned so that, during the relative movement of the each container <NUM> with respect to the vacuum chamber <NUM>, the terminal portion <NUM> of each container relatively moves within the vacuum chamber <NUM> and the main portion <NUM> of each container relatively moves outside the vacuum chamber (and lies on the conveyor <NUM>), with the intermediate portion <NUM> of each processed container passing through and relatively moving along the elongated opening <NUM>.

In order to aid in driving and precisely positioning the terminal portion of each container, the vacuum station may comprise a first guide belt arranged along a length of the elongated opening <NUM> and configured with an outer surface contacting the terminal portion of each processed container: the outer surface of the first guide belt <NUM> is optionally provided with a contoured shape comprising recesses. The vacuum station has also a second guide belt <NUM> arranged along said length of the elongated opening <NUM>, opposed to the first guide belt <NUM> and configured with a respective outer surface contacting the terminal portion of each processed container: also the outer surface of the first guide belt may optionally be provided with a contoured shape comprising recesses. The first and second drive belts <NUM>, <NUM> are endless belts and their motion is controlled by control unit <NUM> or by an further controller of the line <NUM> and is synchronized with the motion of the conveyor <NUM> supporting the containers main portions.

In accordance with another aspect, the vacuum chamber <NUM> may include at least a first sub-chamber 62a and a second sub-chamber 62b (a third or more other sub-chambers <NUM> c may be provided): in this case the vacuum station <NUM> may be configured to provide the first sub-chamber 62a with a first pressure (in general lower than atmospheric pressure present outside the vacuum station) and to provide the second sub-chamber 62b with a second pressure different from, optionally lower than, the first pressure, to improve as possible flexibility of the vacuum station and ability to extract gas from the processed containers.

Note that in addition or in alternative to sealer <NUM> a separate sealing station configured for heat sealing the terminal portions of each container (for example by forming one or more seal bands transversal to the terminal portions) and thus form closed packages may be positioned downstream the vacuum station or downstream the device <NUM> in case the vacuum station and the device <NUM> are deprived of a own sealer.

The lines of <FIG> and <FIG> may also comprise a cutting station <NUM> (see also <FIG>) configured for transversely severing the interconnected containers <NUM> and form a plurality of separated containers: the cutting station <NUM> is operative either immediately downstream the heat shrink apparatus <NUM> or immediately downstream the vacuum station <NUM> (if present) or, in a currently preferred option, downstream the heat shrink device <NUM> (see <FIG> and <FIG>).

In accordance with a further aspect, the lines of <FIG> and <FIG> may also comprise a forming station <NUM> (schematically represented in <FIG>, <FIG> and <FIG>) configured for forming an easy opening feature: the easy opening feature may be a cut or notch or a weakening line formed at one of the peripheral borders of each processed container <NUM>, for example formed at the terminal portion <NUM> of each container. The forming station <NUM> is operative either immediately downstream the heat shrink apparatus <NUM> or immediately downstream the vacuum station <NUM> (if present) or, in a currently preferred option, downstream the heat shrink device <NUM>, for example before or after or even at the cutting station <NUM>.

As shown in <FIG>, <FIG> and <FIG>, the packaging line <NUM> may also include a redirecting station <NUM> configured to orient each processed container <NUM> such that its terminal portion <NUM> is oriented towards a direction of motion of the container downstream the same redirecting station: in the examples shown the redirecting station <NUM> directs the containers transversally with respect to the operating path the containers had upstream the redirecting station <NUM>. The redirecting station <NUM> is operative, in a currently preferred option, downstream the heat shrink device <NUM> and in particular downstream the cutting station <NUM> in order to act on containers which are no longer interconnected.

In the examples shown, the packaging line <NUM> comprises also a heat shrink finisher <NUM> operative downstream the heat shrink apparatus <NUM>, in particular downstream the heat shrink device <NUM>. The heat shrink finisher <NUM> may for example be located immediately upstream the re-directing station <NUM> (if present). The heat shrink finisher <NUM> is configured to direct hot air, optionally hot air at a temperature comprised between <NUM> and <NUM>, at least towards the intermediate portion <NUM> of each processed container to basically heat shrink also the intermediate portion which may have not been properly shrunk at the preceding stations. The heat shrink finisher <NUM> optionally comprises two opposite hot air blowers <NUM> configured for acting on opposite sides of the intermediate portion of each processed container: the two air blowers are independently controlled, for example by control unit <NUM>, and are able to control bending of the terminal portion of each processed container.

Finally, the lines of <FIG> and <FIG> may also comprise a labelling station <NUM> configured for applying at least one label <NUM> to each processed container: in particular, the labelling station <NUM> may be adapted to apply a label <NUM> to the terminal portion of each processed container; the labelling station <NUM> is operative downstream the heat shrink apparatus <NUM>, in particular downstream the heat shrink device <NUM> and, if present, downstream the redirecting station <NUM>. The labelling station includes a label feed roll <NUM>, guide rollers or other guide means <NUM> configured for driving and positioning the adhesive label <NUM> on the portion of interest of each container arriving at the labeling station, and a waste roll <NUM> for receiving the support layer 96a which carried the applied label <NUM>.

A further aspect of the invention concerns a packaging process using the line <NUM> described above for example the packaging line of <FIG> or the packaging line of <FIG>.

The process provides for forming or receiving a plurality of containers <NUM> of the type described above, namely made from heat shrinkable plastic film and having a main portion <NUM> where a product P is housed, a terminal portion <NUM> having at least one aperture 102a allowing gas evacuation from the container, and an intermediate portion <NUM> connecting the main portion and the terminal portion.

In an alternative, preformed containers <NUM> of the type described above either interconnected or separated from each other may be supplied directly to the heat shrink apparatus <NUM>.

In another alternative, which is represented in <FIG> and <FIG>, the process provides for inline forming the containers <NUM>. The forming of the containers may take place at the loader <NUM> described above and may include:.

The almost tubular structure <NUM> has a longitudinal aperture 55a, optionally a longitudinal side aperture, and the containers formed from the almost tubular structure are either in the form of interconnected containers or, if a severing sub step takes place, in the form of a sequence of separated containers.

Irrespective of how the open containers described above are obtained, the process then provides for executing on the containers a process of heat shrinking the main portion <NUM> of the containers using the heat shrink apparatus <NUM> and subsequently executing a process of heat shrinking the terminal portions <NUM> of the processed containers using the heat shrink device <NUM>.

Once or while the terminal portions <NUM> of the containers are been heat shrunk, the process forms a heat seal band across the terminal portion of each processed container to hermetically close said aperture and form closed packages <NUM>.

Note that closure of the containers with a sealer forming a heat seal band may also take place before heat shrinking the terminal portions or after vacuumization at vacuum station <NUM> when this latter is present (variant of <FIG>).

In the variant of line shown in <FIG>, the containers exiting from apparatus <NUM> and thus having their main portions <NUM> heat shrunk are treated at the vacuum station <NUM> described above where withdrawing of gas from each container <NUM> via said aperture 102a is obtained by applying a vacuum from outside each terminal portion <NUM>.

As shown in <FIG>, the steps of receiving the containers at the vacuum station <NUM> and withdrawing gas preferably take place after said main portion <NUM> of the containers housing the product P has been heat shrunk and before heat shrinking the terminal portion <NUM> of containers.

The vacuum station <NUM> applies to the terminal portions <NUM> of the processed containers a pressure inferior to the pressure present inside the main portions, thereby sucking gas from each container via said aperture and forming vacuumized containers having heat shrunk main portions.

The vacuum station <NUM> may be of the type described above in connection with the packaging line of <FIG>. In an option, the vacuum station <NUM> may comprise a own heat sealer <NUM> forming a heat seal band across the terminal portion of each processed container to hermetically close said aperture and form closed packages.

The containers <NUM> or closed packages <NUM> exiting from the vacuum station <NUM> arrive at the shrink device <NUM> where the terminal portions are heat shrunk. Then, if the containers or closed packages are still interconnected they reach cutting station <NUM>, which transversely severs the interconnected containers and forms a plurality of separated containers. Subsequently or at the same time with cutting or before the cutting, a step of forming an easy opening feature (at forming station <NUM>), optionally a cut or notch or a weakening line, at one of the peripheral borders of each processed container is provided: for example forming the easy opening feature may take place after said main portion of the containers housing the product has been heat shrunk, optionally after also said terminal portion of the containers has been heat shrunk.

In the examples show, the process implemented by the lines of <FIG> and <FIG> also comprises a step of redirecting each processed container such that its terminal portion extends forward from the main portion towards a direction of motion of the container: in the examples shown redirecting takes place at redirecting station <NUM>, after said terminal portion <NUM> of the containers has been heat shrunk and before labelling.

Claim 1:
A heat shrink device (<NUM>) for processing containers (<NUM>) of the type made from or comprising heat shrinkable plastic film, the containers (<NUM>) having a main portion (<NUM>) where a product (P) is housed, a terminal portion (<NUM>) not occupied by product (P), and
an intermediate portion (<NUM>) connecting the main portion (<NUM>) and the terminal portion (<NUM>),
wherein the device comprises:
- a pair of opposed shrink belts (<NUM>), each shrink belt (<NUM>) having an operative stretch (31a) facing a corresponding operative stretch (31a) of the opposite shrink belt (<NUM>), wherein said operative stretches (31a) have respective external surfaces defining therebetween, at least in operation, a gap (<NUM>) configured for receiving the terminal portion (<NUM>) of each container (<NUM>) to be processed;
- a belt heater (<NUM>) associated to at least one of said shrink belts (<NUM>) and configured for bringing the external surface of at least one operative stretch (31a) at least at a shrink temperature, optionally comprised between <NUM>° and <NUM>, such that the terminal portion (<NUM>) of each processed container passing through said gap (<NUM>) is heat shrunk.