PROCESS AND APPARATUS FOR PRODUCING PLASTIC PRODUCTS AND PLASTIC PRODUCTS PRODUCED THEREWITH

Abstract

A method for the production of plastic products includes a loading step in which plastic material in granular form is inserted in a containing element, and a heating step, in which the plastic material in granular form is heated until the melting temperature is reached. The method also includes an extrusion step in which the plastic material is conveyed toward extrusion means and extruded to form at least one layer of a film of plastic material and a printing step in which, by means of printing means, at least one layer of printing material is deposited on the film of plastic material to define information associated with the film of plastic material. During the printing step the printing means deposit electrically conductive material on the film of plastic material, according to a predetermined conformation able to define a predetermined electric circuit. The electric circuit comprises electronic memorization means configured to memorize at least predetermined information associated with the type of plastic product to be made.

Claims

1. A method for the production of plastic products comprising: a loading step in which plastic material in granular form is inserted in a containing element, a heating step, in which said plastic material in granular form is heated by heating means associated with said containing element until the melting temperature is reached, an extrusion step in which said plastic material is conveyed toward extrusion means and extruded to form at least one layer of film of plastic material, a printing step in which, by means of printing means, at least one layer of printing material is deposited on said film to define information associated with said film of plastic material, wherein during said printing step the printing means deposit conductive material on said film of plastic material, arriving continuously from said extrusion step, said conductive material being deposited according to a predetermined conformation able to define a predetermined electric circuit, said electric circuit comprising at least electronic memorization means configured to memorize at least information associated with the type of plastic product to be made.

2. The method as in claim 1, wherein in said printing step a passively fed electric circuit is made.

3. The method as in claim 1, wherein said electrically conductive material comprises material of a biodegradable type.

4. The method as in claim 1, wherein said printing step is carried out immediately after the extrusion step.

5. The method as in claim 1, wherein said method provides a step of winding the film onto one or more reels, said printing step being carried out after the extrusion step and before said winding step.

6. The method as in claim 1, wherein said method provides a drawing and stretching of the film after the extrusion step, said printing step being carried out after the drawing and stretching step.

7. A plastic product for non-rigid containing elements, comprising at least one layer of plastic film, wherein said layer of plastic film comprises a printed portion in which information relating to the plastic film itself or to the use of the containing elements made with said plastic film is associated, wherein said printed portion comprises electrically conductive material, having a predetermined conformation defining a predetermined electric circuit, said electric circuit comprises electronic memorization means able to memorize at least predetermined information associated with the type of containing element.

8. A plastic product as in claim 7, wherein said electric circuit is the passively fed type.

9. A plastic product as in claim 8, wherein said electric circuit comprises at least an RFID tag.

10. A plastic product as in claim 7, wherein said electrically conductive material comprises material of the biodegradable type.

11. A plastic product as in claim 7, wherein said layer of plastic film is extruded and said printed portion is formed by conductive material deposited on the film of plastic material arriving continuously from an extrusion head.

12. An apparatus for the production of plastic products, comprising: heating means configured to heat and melt plastic material in granular form, extrusion means, associated with said heating means, configured to extrude the melted plastic material in order to form a layer of film of plastic material, printing means configured to deposit on said film of plastic material at least one layer of printing material to define information associated with the plastic film itself or with the use of the containing elements made with said plastic film, wherein said printing means are configured to deposit electrically conductive material on said plastic film according to a predetermined conformation able to define a predetermined electric circuit, said printing means comprising forming means configured to deposit said electrically conductive material to make at least electronic memorization means in said electric circuit.

13. An apparatus as in claim 12, wherein said printing means are configured to deposit electrically conductive material of the biodegradable type.

14. An apparatus as in claim 12, further comprising writing/reading means configured to cooperate with said memorization means to memorize and/or read predetermined information, said information being associated with the type of plastic product to be made or with the type of objects to be inserted in said containing elements.

15. An apparatus as in claim 12, wherein said printing means are disposed immediately after the extrusion means.

16. An apparatus as in claim 12, further comprising reels for winding the film downstream of the extrusion means, said printing means being disposed after the extrusion means and before said one or more winding reels.

17. An apparatus as in claim 12, further comprising stretching means configured to draw and stretch the film and disposed after the extrusion means, said printing means being disposed after said stretching means.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0055] These and other characteristics of the present invention will become apparent from the following description of a preferential embodiment, given as a non-restrictive example with reference to the attached drawings wherein:

[0056] FIG. 1 is a schematic representation of the method for the production of plastic products according to the present invention.

[0057] To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one embodiment can conveniently be incorporated into other embodiments without further clarifications.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

[0058] We shall now refer in detail to the various embodiments of the present invention, of which one or more examples are shown in the attached drawings. Each example is supplied by way of illustration of the invention and shall not be understood as a limitation thereof For example, the characteristics shown or described insomuch as they are part of one embodiment can be adopted on, or in association with, other embodiments to produce another embodiment. It is understood that the present invention shall include all such modifications and variants.

[0059] Before describing these embodiments, we must also clarify that the present description is not limited in its application to details of the construction and disposition of the components as described in the following description using the attached drawings. The present description can provide other embodiments and can be obtained or executed in various other ways. We must also clarify that the phraseology and terminology used here is for the purposes of description only, and cannot be considered as limitative.

[0060] With reference to the attached drawings, a method for the production of plastic products according to embodiments described here can be used in a continuous production line for plastic films for making non-rigid containers, such as for example bags for containing food products, packing bags, bags for disposing of urban waste.

[0061] In particular, in the case of bags for disposing of solid urban waste, the plastic material used can be the biodegradable type. The bags made using the method described here comprise an RFID tag 75, and can be used in the differentiated disposal of waste, associating each bag with an actual user, allowing to precisely record the quantity of waste disposed of.

[0062] With reference to FIG. 1, the method for the production of plastic products according to embodiments described here can provide to use an apparatus 1 comprising: [0063] heating means 23 configured to heat and melt plastic material in granular form, [0064] extrusion means, hereafter also called extruder 20, associated with the heating means 23, configured to extrude the melted plastic material in order to form at least a layer of film 40 of plastic material, [0065] printing means, hereafter also called printer 70, configured to deposit on the film 40 of plastic material at least one layer of printing material to define information associated with the plastic film itself or with the use of the containing elements made with the plastic film.

[0066] In possible implementations, the extruder 20 can be a bubble extruder.

[0067] In other possible implementations, the extruder 20 can be an extruder with a flat head (cast extrusion).

[0068] In possible implementations, the printer 70 can be disposed immediately after the extruder 20.

[0069] In possible implementations, the apparatus 1 can include reels 80 for winding the film 40 downstream of the extruder 20, said printer 70 being disposed after the extruder 20 and before the one or more winding reels 80.

[0070] In possible implementations, the apparatus 1 can also include drawing and stretching means, also called stretching unit 50, configured to draw and stretch the film 40 and disposed after the extruder 20. In particular, the stretching unit 50 can be configured to draw and stretch the extruded film. For example, the stretching unit 50 can be the oscillating type. In possible implementations, the stretching unit 50 can include drawing and stretching rolls. Furthermore, the stretching unit 50 can have cooled rolls depending on the characteristics to be imparted to the film. In possible implementations, for example in particular in the case of bubble extrusion, the stretching unit can be a so-called tip roller.

[0071] In possible implementations, the apparatus 1 can include a control and processing unit 5, a measurer 6, a loading hopper 10, the extruder 20, the stretching unit 50, rolls 60, the printer 70 and one or more of the winding reels 80.

[0072] In some embodiments, the method provides a first step, or loading step, in which plastic material in granular form is inserted inside the feed or loading hopper 10. The material is introduced into the hopper 10 which is in turn connected to the measurer 6, of a known type and not described any further here. The measurer 6 releases the desired quantity and measure of plastic material according to the commands received from the control and processing unit 5 as will be described in more detail hereafter. The hopper 10 is connected by means of a first tubular pipe 4, or feed pipe, to the extruder 20.

[0073] The method provides a second step in which the plastic material in granular form unloaded inside the extruder 20 is heated. Indeed, the extruder 20 comprises a heating chamber 21 provided with heat resistances 23 by means of which the plastic material is heated until it reaches the melting temperature. The extruder 20 also comprises mechanical conveyors associated with the heating chamber 21, of a known type and not shown, and an extrusion head 30, connected to the heating chamber 21 by means of a second pipe 22. The plastic material in melted form is thrust at high pressure, by means of a screw (not shown), toward the extrusion head 30.

[0074] The method also comprises an extrusion step in which the plastic material in melted form is made to exit at high pressure from the extrusion head 30 to form a film 40, substantially non-rigid. The extrusion head 30 is also provided with an air ring 32, which has a circular shape and is suitable to emit air to cool the plastic material exiting. The air ring 32 allows to make the melted plastic material come out in the form of a film 40 with a bubble conformation and subsequently to convey it toward the stretching unit 50. In possible embodiments, the method provides a step of drawing and stretching the film 40 using the stretching unit 50, after the extrusion step.

[0075] The film 40 is then made to advance through a succession of cooling rolls 60, disposed so as to keep the film 40 always in predetermined tension conditions.

[0076] The production method also comprises a printing step in which the film 40 of plastic material is made to pass in correspondence with the printer 70, interposed between two adjacent rolls 60, so as to deposit the printing material on a surface portion of the film 40 in desired tension conditions and to conform a flat portion of film 40 on which to print. Therefore, for example, the printing step using the printer 70 can be carried out after the drawing and stretching step done with the stretching unit 50. It is understood that the printer 70 can be disposed in any other suitable position in the production line of the plastic film.

[0077] During the printing step, the printer 70 deposits in predetermined positions on the surface of the film 40, and in coordination with the feed of the film 40, one or more layers of electrically conductive material and one or more layers of electric insulating material in a desired conformation and so as to obtain a predetermined electric circuit comprising the RFID tag 75. In particular the printer 70 deposits both a first portion of electrically conductive material to obtain the antenna of the RFID tag 75 and also a second portion of electric circuit to obtain a non-volatile memory of the RFID tag 75.

[0078] In particular, the printer 70 comprises forming means, such as for example a photolithographic mask 72, by means of which the electrically conductive material is deposited on the film 40 of plastic material according to a predetermined electric topography such as to obtain the configuration of the RFID tag 75, in this case both the antenna and the non-volatile memory.

[0079] It is understood that the printing step can be carried out by any other known printing technique, such as for example described in the document Technologies for Printing Sensors and Electronics Over Large Flexible Substrates: A Review by Khan et al. For example the conductive material can be deposited by silk screen printing techniques, ink jet or slot-die printing.

[0080] In one embodiment of the present invention, the electrically conductive material comprises biodegradable material, such as for example magnesium. In this way the bag made is completely biodegradable and recyclable, making the invention particularly suitable for use in the disposal of all types of urban waste, and in particular wet urban waste or compost.

[0081] The control and processing unit 5 controls the measurer 6, the extruder 20 and the printer 70 to make the film 40 come out of the stretching unit 50, in coordination with the speed of feed of the film 40 in the apparatus 1. In fact, the printing and depositing speed of the printer 70 is regulated according to the speed of feed of the film 40 itself, and vice versa. The apparatus 1 comprises one or more speed sensors of the known type (not shown in the drawings), for example a rotation encoder, associated with at least one of the rolls 60 and/or the reels 80 and suitable to measure continuously the speed of feed of the film 40. The encoders are connected to the control and processing unit 5 to detect continuously the speed of feed of the film 40 at different points of the apparatus 1. The control and processing unit 5 can in this way verify that the speed of feed of the film 40 and the printing speed of the printer 70 are as established. Therefore, the control and processing unit 5 sends to the measurer 6 the measuring commands so as to determine the delivery of a type and quantity of granular plastic material such as to guarantee the production and exit of the film 40 from the stretching unit 50 with pre-set rheological properties and transverse and longitudinal surface tension and at a speed coordinated to the printing speed.

[0082] It is understood that the encoder can in turn be associated with an electronic feedback circuit of a known type (not shown), and directly connected to the printer 70 or the control and processing unit 5 and such as to adjust the printing or depositing speed of the electric material of the printer 70 according to the value of speed of feed of the film 40 as detected by the encoders.

[0083] The apparatus 1 also comprises temperature sensors 62 disposed in different positions, to continuously detect the temperature at different points of the line, for example of the heating chamber 21 and the extrusion head 30. The temperature sensors 62 are connected to the control and processing unit 5 to send feedback data of the process to it, together with the data arriving from the speed sensors.

[0084] The apparatus 1 also comprises pressure sensors, typically associated with the extruder 20, of a known type and not shown here, which are connected to the control and processing unit 5 and detect the pressure value inside the extruder 20. Based on the temperature values detected in the apparatus 1, the pressure values in the extruder 20, the value detected of the speed of feed of the film 40 and the specific properties of the plastic film to be obtained, the control and processing unit 5 controls the measurer 6, the resistances 23 and the printer 70 so as to determine the exit of the film 40 from the stretching unit 50, and the depositing by the printer 70 of the conductive material in order to make the tags 75.

[0085] By way of non-restrictive example, in order to deposit ink of conductive material with a PEDOT base on a film obtained starting from an LDPE type resin, so as to obtain an accurate and precise deposit of the conductor tracks and with desired thicknesses, in the range of about ten micrometers, the control and processing unit 5 adjusts and corrects the parameters of the production line substantially continuously. In the case of a film consisting of an external layer comprising metallocene-polyethylene resin with a melt index (at 190 C., 2.16 kg) equal to 1.3-1.4 g/10 min, the percentage of PEDOT that makes up the ink is in a range that goes from 13% to 26%. In particular, to obtain a film 40 that has a predetermined coefficient of ultimate elongation, measured in percentage unit as a parameter of the ISO test method, resistance to tearing, measured in N/mm as a parameter of the ISO test methods, and resistance to impact, measured in grams as a parameter of the ISO test method, the control unit 5 must precisely adjust the composition of the film 40. In particular the control unit 5 acts on the measurer 6 to release a desired quantity and mixture of plastic material in granular form to the extruder 20. The control unit 5 also detects, as already described above, the speed of feed of the film 40 by the speed detectors, the process temperature by the temperature sensors 62, the environmental temperature by means of corresponding temperature sensors (not shown) and the pressure in the extruder 20. The control unit 5 also detects, in a known manner, the surface tension of the film, measured in dynes.

[0086] The deposit of the conductive material in order to make the RFID tags 75 during the production of the plastic film 40 allows to control precisely both the thickness of the tags deposited and also, possibly, to at least partly drown the tags inside the film, as the deformability of the plastic film 40 can be exploited during production. In this way it is possible to prevent problems of overlapping of the tags 75 in the subsequent winding step, reducing to a minimum the thickness tolerances required.

[0087] Furthermore, seeing that the production process of a plastic film by extrusion is a process that, given the same polymer material used, depends on the working conditions and on specific additives used during working, in the method according to the present invention the depositing of the RFID tags 75 made directly in the production line of the plastic film allows for example to modify the color and transparency of the plastic film itself in combination with the specific tags. In the known methods of the roll-to-roll type, this is not possible because the film has already been made and the properties can no longer be modified.

[0088] It is understood that the direct depositing of tags 75 on plastic films during the production process of the films 40 allows to reduce the times needed to select both the printing materials, for example the inks in the case of ink-jet printing, and the specific composition of the polymers. In fact, said selection and composition operations can be carried out during the equipping of the line, verifying that the properties of the film produced are in conformity with those predetermined.

[0089] In one embodiment of the present invention, not shown in the attached drawings, the printer of the ink-jet type comprises at least two printing cartridges, a first cartridge intended to contain conductive ink and a second cartridge to contain insulating ink. In another embodiment, the printer 70 comprises two or more delivery cartridges and as many ink mixers in which the mixers take the components to generate respectively conductive inks and insulating inks to be deposited on the plastic film 40 according to its specific properties. In this way it is possible to modify in real time the specific composition of the printing materials, that is, of the inks, according to the specific composition of the plastic film 40 produced, since the control and processing unit 5 can act simultaneously both on the parameters of the extruder 20, as described before, and also on the mixing of the conductive and insulating inks.

[0090] The method then comprises a memorization step in which, by means of an RFID tag reader/writer 77, disposed near the printer 70 and advantageously connected to a control unit, such as a personal computer, not shown in the drawings, on each RFID tag 75 of the film 40 during the feed step, predetermined information is memorized, such as for example the type of bag that will be produced, its intended use, a unique serial number that univocally identifies each bag produced using the present method. In this way it is possible to produce rubbish bags that can be associated with the final user and to memorize additional information in the RFID tag 75, also at a later time, such as the identity of the user and hence obtain an association between the specific bag and the user. This allows for example in the case where the bags produced with the method according to the present invention are used for the disposal of solid urban waste, to precisely record the quantity of waste produced, associating it with the specific user.

[0091] For example, if the plastic film 40 is intended for making bags for the food sector, it is possible to memorize in the RFID tags 75 information relating to the date of production of the film, the producer of the food products, the duration of the film or the type of food compatible with the plastic film.

[0092] It is understood that the tag reader/writer 77 can be incorporated in the printer 70, or that it can be disposed in another position of the apparatus 1 for the production of plastic products according to the present invention.

[0093] In one embodiment of the method according to the present invention, the tag reader/writer 77 only controls the presence of the RFID tag 75 on the film 40 or possibly on the finished bag. In this way it is possible to verify the correct printing of the RFID tag 75 on every portion of film 40 or on every bag thus produced.

[0094] The method also comprises a winding step in which the film 40 on which the RFID tags 75 are printed is wound onto a reel 80 to then be sent to subsequent work steps in one of which the film 40 wound on the reel 80 is for example die-cut or cut to size, and in coordination with the positions of the RFID tags 75 printed on the film 40 to obtain the bags. According to one embodiment, not shown here, the method does not include the winding step, but a direct step of cutting or die-cutting, in which the film is cut or die-cut to size after the RFID tag 75 has been deposited and made available as a finished product. In this case it is obvious that the production costs of the containing elements are considerably reduced, since no further winding steps are required.

[0095] It is understood that the method according to the present invention can also provide a step of treating the plastic film 40, to facilitate the adhesion of the printing material. For example, the method can provide a known step, not further described here, of crown or plasma treatment, performed before the printing material has been deposited in order to increase the intrinsic surface energy of the plastic film 40.

[0096] It is clear that modifications and/or additions of parts may be made to the apparatus 1 and the method for the production of plastic products and the plastic products as described heretofore, without departing from the field and scope of the present invention.

[0097] For example, it comes within the field of the present invention to provide that the memorization means comprise an NFC (Near Field Communication) chip or other type of semi-conductor circuit of the wireless type, and passive, fed by an electromagnetic field interacting with the memorization means deposited on the film 40 of plastic material.

[0098] It also comes within the field of the present invention to provide that the printer 70 deposits electrically conductive material so as to obtain other circuit components, such as for example a weight measurer or an extensometer. In this way, if the bags are used for rubbish disposal, with the bags made with the film 40 of plastic material according to the present invention it is possible not only to memorize the specific user and the type of waste disposed of, but also to calculate the corresponding weight, or possibly the volume, thus facilitating the operations to manage and charge for the waste.

[0099] It is clear that modifications and/or additions of parts and/or steps may be made to the method for the production of plastic products, the corresponding production apparatus and the plastic products thus obtained as described heretofore, without departing from the field and scope of the present invention as defined by the claims.

[0100] It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of the method for the production of plastic products, the corresponding production apparatus and the plastic products thus obtained, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.

[0101] In the following claims, the sole purpose of the references in brackets is to facilitate reading: they must not be considered as restrictive factors with regard to the field of protection claimed in the specific claims.