WO2016059572A2

WO2016059572A2 - A plant and method for making a plastic film

Info

Publication number: WO2016059572A2
Application number: PCT/IB2015/057872
Authority: WO
Inventors: Renato Federici
Original assignee: Polimer Sas Di Federici Renato E C
Current assignee: Polimer Sas Di Federici Renato E C
Priority date: 2014-10-16
Filing date: 2015-10-14
Publication date: 2016-04-21
Anticipated expiration: 2017-04-16
Also published as: WO2016059572A3

Abstract

A plant (10) for making a plastic film (11), in particular tubular or in a flat sheet, preferably intended for making sacks, bags and the like, comprising means (12) for forming the film (11) in the form of a bubble (15) starting with a respective molten mass of plastic material, which is fed to the forming means (12) by corresponding means (14) for extruding a relative raw material (13), which comprise a compounding extruder (18).

Description

DESCRIPTION

A PLANT AND A METHOD FOR MAKING A PLASTIC FILM. Technical field

This invention relates to a plant and a method for making, in particular for extruding, a plastic film, especially in the tubular or flat sheet form.

Background art

There are prior art plants for making tubular plastic film, for making sacks, bags and the like, which comprise means for forming the film in the form of a bubble, starting from a respective molten mass of plastic material made by corresponding extruding means in the form of a single-screw extruder, which heats and extrudes, until melting, a raw material composed of granules or particles obtained by compounding pure polymers, such as, for example, polyethylene, polypropylene or the like, or biodegradable polymers or obtained from recycled plastic, with particular addition of additives and/or fillers, in particular mineral fillers.

One problem seen in use of the prior art plants has been noted, in particular, with the use of compounds obtained from recycled or regenerated plastic, which have a non-uniform composition which easily gives rise to the development of gas, which thus have the drawback of forming irregularities, in particular the so-called 'soft corn' marks, in the film being formed, with consequent irreparable damage to the product. The so-called single-screw extruders used in the plants for extruding a film configured in the form of a bubble are conceived for directly compressing the molten raw material in the head for forming the bubble of film and are therefore configured for keeping the mass in a high pressure condition and must necessarily operate starting from raw materials already compounded. In practice, with the use of the so-called single-screw extruders, in the plants for making plastic film in the form of a bubble, a considerable use of energy is required for heating and compressing the plastic mass, which is added to the energy already used for making the compounded material, which is then used in the film extruding plants.

The need is therefore felt in the trade of having plants or methods for making the plastic film wherein the drawbacks to the film can be overcome resulting from unsuitable or low quality raw material, in particular regenerated or recycled raw material, avoiding in particular the production of damaged film which must therefore be rejected.

The general need is also felt in the trade of having plants or methods which allow an overall energy saving to be achieved, with obvious advantages in terms of protection of the environment, especially in terms of less pollution of the environment.

Summary of the Invention

This invention therefore proposes a new solution as an alternative to the solutions known up to now and, more specifically, proposes to overcome one or more of the above mentioned drawbacks and/or problems and/or to meet one or more of the needs felt in the trade or inferable from the above.

A plant is provided for making a plastic film, in particular tubular or in a flat sheet, preferably intended for making sacks, bags and the like; comprising means for forming the film in the form of a bubble starting with a respective molten mass of plastic material, which is fed to the forming means by corresponding means for extruding a raw material received from respective means for loading the raw material in the plant; characterised in that the means for extruding the raw material comprise a compounding extruder.

In this way, it is possible to make the compound of desired raw materials directly during the step for extruding the raw material, with consequent energy advantages, that is to say, with consequent elimination of the previous step of compounding the material.

In practice, during the melting of the raw material, which is compressed in the means for making the film, compounding of the same raw material is performed simultaneously.

This makes it possible to avoid having to process the material previously compounded with a considerable overall energy saving.

The invention further provides an advantageous method for making a plastic film.

Brief description of the drawings

These and other innovative aspects are set out in the appended claims and its technical features and advantages are apparent from the detailed description which follows of a preferred, advantageous embodiment of it, which must be considered purely as a non-limiting example, the description being made with reference to the accompanying drawings, in which:

- Figure 1 is a schematic view of a preferred embodiment of the plant according to this invention;

- Figure 2 is a schematic lateral view of the extruding means used in the preferred embodiment of the plant according to this invention;

- Figure 3 is a schematic front view of the preferred embodiment of the extruding means used in the preferred embodiment of the plant according to this invention;

- Figure 4 is a perspective view of a preferred embodiment of degassing means which are used in the means for extruding the raw material. Detailed description of preferred embodiments of the invention

Figure 1 illustrates a schematic view of an embodiment of the plant 10 for making a plastic film 11 , in particular tubular or in a flat sheet, preferably intended for making sacks, bags and the like.

As illustrated, the plant 10 comprises means 12 for forming the film 11 in the form of a bubble 15 starting with a respective molten mass of plastic material, which is fed to the forming means 12 by corresponding means 14 for extruding a raw material 13.

As illustrated, the plant also comprises means 16 for loading the raw material on the extruding means 14.

Advantageously, as may be inferred also from Figures 2 and 3, the plant comprises means 14 for extruding the raw material, which include a respective compounding extruder 18.

In practice, in this way, a method is implemented for making a plastic film 11 , preferably tubular in shape, and in particular for making sacks, bags or the like, using respective means 12 for forming the film 11 , in the form of a bubble 15, starting from a respective molten mass of plastic material, wherein, advantageously, a respective molten mass is melted and compounded, which is fed directly to the means for making the film 11. This prevents a waste of energy for making, in a step before making the plastic film, the compounds defining the raw material.

In this way, it is also possible to make the compound of desired raw materials and use them immediately transforming them into plastic film, thus avoiding the need for storage and the consequent risk that this incorporates undesired humidity.

As illustrated, once produced, the film 11 may be placed on suitable collection reels 111 , preferably to be sent to the plants for making sacks, bags and the like.

More specifically, the raw material used comprises plastic which is recycled, or regenerated, after consumption.

In this case, thanks to this plant and method, it is possible to avoid the risk that any gas which forms during the extrusion of the raw material can damage the plastic film produced, as the extruding means advantageously allow the removal of the gas during the extruding step in the compounding extruder 14.

More specifically, the raw material used comprises a biodegradable and/or compostable polymer. In this case, it is possible to compound the biodegradable and/or compostable polymer with mineral filler which is advantageous in terms of biodegradability of the product obtained and without requiring the prior formation of compound which comprises the biodegradable and/or compostable polymer and corresponding mineral filler, thus achieving an considerable overall energy saving.

Is also be imaginable the fact that the raw material used comprises respective pure polymers, such as, for example, polyethylene and/or polypropylene or mixtures of the pure polymers.

According to this advantageous method, the raw material used also comprises additives and/or fillers, in particular mineral fillers.

Advantageously, in this plant, the means 12 for extruding the raw material comprise advantageous means 22 for compressing the molten mass in the forming means 12.

More specifically, as illustrated, the compressing means 22 are positioned downstream of the compounding extruder 18.

Further advantageously, the means 14 for extruding the raw material comprise means 20 for filtering the molten mass, in particular operating with a continuous flow, which are in particular positioned downstream of the compounding extruder 18 and upstream of the compressing means 22.

Advantageously, the means 20 for filtering the molten mass are of the automatic filter change type, in such a way as to keep a continuous flow of the molten mass towards the means 12 for forming the film during the entire process for forming the plastic film.

Further advantageously, the means for compressing the molten mass in the means 12 for forming the plastic film, especially comprising a respective compression pump 22, which is, in particular, operating with continuous flow and is preferably in the form of a pump of the gear pump type, which advantageously increases the pressure of the molten mass flowing out from the compounding extruder 18 up to a pressure level sufficient to compress it in the corresponding head, or means, for forming the plastic film 12 in the form of a bubble. In more detail, advantageously these compression means 22 are provided such as to change the pressure of the molten mass to a level equal to 300 bar, which is particularly suitable to feed the corresponding head for forming the film in the bubble 12, in particular starting from quite a low pressure of the molten mass escaping from the compounding extruder 18, which has, for example, a pressure level equal to 80 bar.

More specifically, advantageously, the compounding extruder 18 is in the form of an extruder of the twin-screw type.

More specifically, the twin-screw type extruder could be made from respective screws, or spirals, either co-rotating or contra-rotating, the latter being particularly advantageous for processing biodegradable raw materials, that is, such as to prevent the decay of the respective particle. More specifically, the compounding extruder could be in the form of a conical twin-screw type extruder, that is, a parallel twin-screw type extruder.

Another compounding extruder may be made in the form of an extruder having a single rotatable screw, whose respective screw body has an additional alternating movement according to the line of the axis of rotation.

Advantageously, the compounding extruder 18 comprises a series of successive stages 181 for thermal conditioning of the extruded mass, in particular for heating the mass during forming, which allow a homogeneous and optimum mass to be made, in a suitable manner, even starting from different types of raw material.

Further advantageously, the compounding extruder 18 comprises respective means 24 for degassing the molten mass.

In this way, it is possible to make a uniform molten mass which can be compressed directly in the means 12 for forming the plastic film.

More specifically, advantageously, the compounding extruder 18 comprises a plurality, in particular first and second, means 24, 24 or units for degassing the molten mass, which are labelled 24, 24 in the accompanying drawings.

As illustrated, advantageously, the first and second means 24, 24 for degassing the molten mass are provided longitudinally spaced from each other along the linear or longitudinal extension of the extruder 18.

In this embodiment the degassing means 24 are in the form of venting means positioned at the top of the hollow body, or cylinder, forming the inner chamber of the extruder 14 and in communication with the inner extruding chamber of the compounding extruder 14.

According to an alternative different and preferred embodiment, use might be made, alternatively or in addition to the venting means 24, of degassing means 240, of the type illustrated in Figure 4. It relates to degassing means which can be positioned laterally to the hollow body, or cylinder, forming the inner chamber of the compounding extruder 14, as indicated with a dashed line in Figure 2, and which are in communication with the inner extrusion chamber of this and which in particular are such as to allow the degassing of the molten mass without allowing any escape of the raw material of the mass.

In the embodiment illustrated in Figure 4, these degassing means 240 without escape of material comprise a first and a second screw 241 , 241 , leading into the extruding chamber defined by the outer cylinder of the compounding extruder 14, and coming out from a respective duct 242, which operate on the molten mass in such a way as to keep the mass inside the extruding chamber, whilst allowing gas to come out of the extruding chamber through the same duct 242 and, therefore, outside the device 240 through the opening 243.

More specifically, these degassing means 240 are positioned downstream of the zones 162 and/or 26 for inserting the raw material.

Advantageously, the compounding extruder 18 also comprises means 26 for inserting a secondary raw material, preferably in the form of a mineral filler, preferably consisting of calcium carbonate, talc, kaolin and other substances. More specifically, the means 26 for inserting a secondary raw material are, in particular, located downstream of the corresponding means 162 for inserting the main raw material fed through the loading means 16, which introduce the main raw material at an upstream end of the compounding extruder 18, as may be well inferred from Figure 2.

Advantageously, the means 26 for inserting a secondary raw material are also designed to define respective means, or units, for degassing the molten mass.

More specifically, advantageously, the means 16 for loading the raw material are designed to feed a respective raw material, comprising one or more of the following materials: particles or granules of recycled or regenerated plastic, in particular particularly regenerated, granules of biodegradable and/or compostable polymer, granules of pure polymers, additives and/or fillers, in particular mineral fillers.

More specifically, as illustrated, the loading means comprise respective loading hoppers 162, 162, each being designed preferably to receive a corresponding raw material, or a respective component part of the raw material, in particular of the main raw material.

As illustrated, advantageously, the means 26 for inserting the secondary raw material are located at an intermediate position of the compounding extruder 18, in particular downstream of the means 162 for inserting the main raw material.

Advantageously, as illustrated, the degassing means 24 are provided at and/or downstream of the means 26 for inserting the secondary raw material.

As illustrated, the raw material extruding means 14 comprise, at the end downstream of the compounding extruder 18, means 28 designed to render uniform and/or to compact the molten mass of material coming out of the compounding extruder 18.

Advantageously, the extruding means 14 comprise outfeed means for the molten mass, in particular downstream of the compressing means 20, the outfeed means for the molten mass 141 being directly connected to a respective infeed 121 in the film forming means 12.

As illustrated, the extruding means 14 comprise a respective motor 8 connected through a respective reducer 9 to the shaft, or axis, of rotation of the extruding feeder(s), or screw(s), as well as corresponding means 7 for cooling the motor.

This provides a plant and method which allows the extrusion in a continuous cycle, and therefore in a particularly advantageous manner, of a respective film, in tubular or flat sheet form.

The invention described has evident industrial applications. It would be obvious to one skilled in the art that several changes and modifications can be made to the invention without departing from the spirit and scope of the invention, described in depth above. It is also easy to imagine further embodiments of the invention comprising one or more of the features described herein. Moreover, it will be understood that all the details of the invention may be substituted for technically equivalent elements.

Claims

1. A plant (10) for making a plastic film (1 1 ), in particular tubular or in a flat sheet, preferably intended for making sacks, bags and the like; comprising means (12) for forming said film (1 1 ) in the form of a bubble (15) starting with a respective molten mass of plastic material, which is fed to said forming means (12) by corresponding means (14) for extruding a raw material (13) received from respective means (16) for loading the raw material in the plant; characterised in that said means (14) for extruding the raw material comprise a compounding extruder ( 8).

2. The plant according to claim 1 , characterised in that said means (14) for extruding the raw material comprise means (22) for compressing the molten mass in said forming means (12), in particular downstream of said compounding extruder (18).

3. The plant according to either of the preceding claims, characterised in that said means (14) for extruding the raw material comprise means (20) for filtering the molten mass, in particular downstream of said compounding extruder (18) and upstream of said compressing means (22).

4. The plant according to claim 3, characterised in that said means (20) for filtering the molten mass are of the type with continuous flow or automatic filter change.

5. The plant according to any one of the preceding claims 2 to 4, characterised in that said means for compressing the molten mass in said means (12) for forming the plastic film comprise a respective compression pump (22), preferably operating with continuous flow, in particular of the gear pump type.

6. The plant according to any one of the preceding claims, characterised in that said compounding extruder (18) is in the form of an extruder of the counter-rotating twin-screw type.

7. The plant according to any one of the preceding claims 1 to 5, characterised in that said compounding extruder (18) is in the form of an extruder of the co-rotating twin-screw type.

8. The plant according to any one of the preceding claims 1 to 5, characterised in that said compounding extruder (18) is in the form of an extruder having a single rotatable screw, whose respective screw body has an additional alternating movement according to the line of the axis of rotation.

9. The plant according to any one of the preceding claims, characterised in that said compounding extruder (18) is in the form of an extruder of the conical twin-screw type or of the parallel twin-screw type.

10. The plant according to any one of the preceding claims, characterised in that the compounding extruder (18) comprises a series of stages (181 ) one after another for thermal conditioning of the extruded mass, in particular for heating said mass.

1 1. The plant according to any one of the preceding claims, characterised in that the compounding extruder (18) comprises means

(24) for degassing the molten mass.

12. The plant according to claim 1 1 , characterised in that the compounding extruder (18) comprises a plurality, in particular first and second, means (24, 24) or units for degassing the molten mass.

13. The plant according to any one of the preceding claims, characterised in that the compounding extruder (18) comprises means (26) for inserting a secondary raw material, preferably in the form of a mineral filler, in particular in the form of calcium carbonate, talc, kaolin and other substances.

14. The plant according to claim 13, characterised in that said second inserting means (26) for inserting a secondary raw material are, in particular, located downstream of the means (162) for inserting the main raw material through said loading means (16).

15. The plant according to claim 13 or 14, characterised in that said means (26) for inserting a secondary raw material are designed to form means for degassing the molten mass.

16. The plant according to any one of the preceding claims, characterised in that said means (16) for loading the raw material are designed to feed a respective raw material, comprising one or more of the following materials: particles or granules of recycled or regenerated plastic, in particular particularly regenerated, granules of biodegradable and/or compostable polymer, granules of pure polymers, additives and/or fillers, in particular mineral fillers.

17. The plant according to any one of the preceding claims, characterised in that said loading means (16) comprise respective loading hoppers (162), preferably each being designed to receive a corresponding raw material, or component part of the raw material, in particular of the main raw material.

18. The plant according to any one of the preceding claims, characterised in that said means (26) for inserting the secondary raw material are located at an intermediate position of said compounding extruder (18), in particular downstream of said means (162) for inserting the main raw material.

19. The plant according to any one of the preceding claims 11 to 18, characterised in that said degassing means (24) are provided at and/or downstream of said means (26) for inserting the secondary raw material.

20. The plant according to any one of the preceding claims 11 to 19, characterised in that said degassing means (24) are in the form of venting means positioned at the top of the hollow body forming the inner chamber of the extruder (14).

21. The plant according to any one of the preceding claims 11 to 20, characterised in that said degassing means (240) are positioned at the side of the hollow body forming the inner chamber of the extruder (14).

22. The plant according to any one of the preceding claims 11 to 21 , characterised in that said degassing means (240) are designed to allow degassing of the molten mass without allowing any of the raw material of said mass to come out.

23. The plant according to claim 22, characterised in that said degassing means (240) comprise a first and a second screw (241 , 241), leading into the extruding chamber of said compounding extruder (14), said screws coming out of a respective duct (242) and operating on the molten mass in such a way as to keep the mass inside the extruding chamber, whilst allowing gas to come out of the extruding chamber through said duct (242).

24. The plant according to any one of the preceding claims, characterised in that said raw material extruding means (14) comprise, in particular provided at the end downstream of said compounding extruder (18), respective means (28) designed to render uniform and/or to compact the molten mass coming out of the compounding extruder (18).

25. The plant according to any one of the preceding claims, characterised in that said extruding means (14) comprise outfeed means for said molten mass, in particular downstream of said compressing means (20), which are directly connected to a respective infeed (121 ) in said film forming means (12).

26. A method for making a plastic film ( 1), in particular tubular or in a flat sheet, preferably intended for making sacks, bags and the like; the method comprising making said film using respective means (12) for forming said film (11), in the form of a bubble (15), starting with a respective molten mass of plastic material, characterised in that it comprises melting and simultaneously compounding a respective molten mass, which is fed directly to the means for making said film (11).

27. The method according to claim 26, characterised in that it is implemented using a plant according to any one of the preceding claims 1 to 25.

28. The method according to claim 26 or 27, characterised in that the raw material used comprises a recycled or regenerated plastic.

29. The method according to any one of the preceding claims 26 to 28, characterised in that the raw material used comprises a biodegradable and/or compostable polymer.

30. The method according to any one of the preceding claims 26 to 29, characterised in that the raw material used comprises pure polymers.

31. The method according to any one of the preceding claims 26 to 30, characterised in that the raw material used comprises additives and/or fillers, in particular mineral fillers.

32. A plant and a method, each respectively characterised in that it is as described in any one of the corresponding preceding claims and/or as described and illustrated with reference to the accompanying drawings.