Methods for selecting and separating polymers derived from municipal and / or industrial plastic waste

Abstract

This invention relates to a method for selecting and separating polymers derived from urban and / or industrial plastic waste to obtain plastic materials for recycling, the method comprising a first step of supplying a mixture of polymers consisting of sheets of polymers ranging in size from 6 mm to 100 mm; a step of identifying sheets of colored and white plastic materials and sheets of black plastic materials by near-infrared (NIR) spectroscopy and subsequently separating them from each other; and several successive steps of identifying different types of polymers from the colored and white plastic materials by NIR spectroscopy and subsequently separating said polymer types.

Description

Technical Field

[0001] This invention relates to a method for selecting and separating polymers derived from urban and / or industrial plastic waste to obtain plastic materials for recycling. Background Technology

[0002] Given the vast amounts of plastic waste generated at both household and industrial levels, plastic disposal constitutes a significant environmental problem, particularly in most industrialized countries. While most plastics currently end up in landfills or are simply discarded into the environment at the end of their lifespan, several technologies and processes exist today attempting to address the issue. Various methods and technologies are employed to tackle this problem, including incineration, remelting of plastics for the production of new items, and biodegradation (if the plastic is biodegradable). However, it is known that only a relatively small fraction of currently produced plastics are biodegradable.

[0003] Each of the methods mentioned above results in a loss of value of the product obtained after conversion relative to the value of the original plastic. This is evident in the case of combustion (given that the plastic is used only as fuel in this technology) and equally evident in the case of biodegradation (given that the product obtained from biodegradation is used for applications with low economic value, such as as a soil conditioner in agriculture, or as a solid fuel after further conversion).

[0004] Similarly, in the case of remelting of plastics used to produce articles, there is a loss of value because the articles obtained from recycled plastics are used in applications with a lower value than the original products.

[0005] None of the technologies mentioned above can restore the original value of plastic, because it is obviously impossible to convert recycled plastic back into virgin plastic.

[0006] Therefore, the significant annual loss of virgin plastics necessitates the production of new plastics to replace the vast majority discarded plastics in the environment and to convert them into other product plastics intended for applications different from those of virgin plastics. Furthermore, the production of new plastics negatively impacts the availability of fossil resources used as raw materials for plastic production.

[0007] In recent years, technologies have been developed and advanced to differentiate plastic materials derived from waste in order to obtain reusable materials and thus reduce the production of virgin materials.

[0008] However, conventional separation techniques cannot achieve a high purity percentage of the selected polymer, and therefore are heavily contaminated by other types of polymers, making them only suitable for producing low-quality products.

[0009] In this context, the technical objective of the present invention is to provide a method for mechanically separating polymers from a mixture of polymers derived from commercial and / or industrial plastic waste, the method being able to distinguish and separate different materials to obtain recycled materials with high purity.

[0010] Therefore, a method for selecting and separating selected polymers with high precision to obtain fractions of the material with high purity, distinguishable in both material type and color, would be desirable.

[0011] Methods capable of continuous and uninterrupted operation to handle the selection and separation of large quantities of materials would also be desirable. Summary of the Invention

[0012] In particular, one object of the present invention is to provide a separation method that can obtain a separated portion of polymer material with a purity of more than 95%, which can replace part or all of the original material for the production of high-quality articles.

[0013] Another object of the present invention is to provide a separation method that can further select and separate different types of plastic materials according to color to obtain single material and single color products that can be directly reused in the plastics industry.

[0014] Another object of the present invention is to provide a method for separating polymers, which is capable of selecting and separating different types of polymers even when the plastic material is black, to obtain a portion of a high-purity material that is also of that material type.

[0015] Another object of the present invention is to provide a method for separating polymers, the method being capable of continuous operation to select and separate large quantities of materials.

[0016] The above and other objects and advantages of the invention, which will become clear from the following description, are achieved by the method according to claim 1.

[0017] Specifically, the objective is achieved by a method of mechanically selecting and separating at least two polymers from a mixture of polymers derived from commercial and / or industrial plastic waste, the method comprising the following steps:

[0018] i. Provide a mixture of polymers derived from commercial and / or industrial plastic waste, consisting of polymer sheets ranging in size from 6 mm to 100 mm;

[0019] ii. Identify the sheets of colored and white plastic material by near-infrared (NIR) spectroscopy, and separate the portion of the sheets rich in colored and white plastic material (F1) and the portion of the sheets rich in black plastic material (F2) by a suitable separation method;

[0020] iii. Identify the polymer P1 flakes from the portion (F1) of the flakes rich in colored and white plastic material separated in step ii by NIR spectroscopy, and separate the portion (F3) of the polymer P1-rich flakes from the portion (F1) of the flakes rich in colored and white plastic material by a suitable separation means, thereby obtaining the portion (F4) of the flakes poor in polymer P1.

[0021] iv. Identify a polymer different from P1 from the portion (F3) of the polymer-rich sheet separated in step iii by NIR spectroscopy, and separate a portion (F5) of the sheet rich in polymer different from P1 from the portion (F3) of the polymer-rich sheet by a suitable separation means.

[0022] v. Identify the polymer P2 flakes from the fraction (F4) of the polymer-poor flakes separated in step iii and from the fraction (F5) of the flakes rich in polymers different from P1 separated in step iv by NIR spectroscopy, and separate the fraction (F6) of the polymer-poor flakes from the fraction (F1) of the flakes rich in colored and white plastic materials by suitable separation means, thereby obtaining the fraction (F7) of the polymer-poor flakes.

[0023] vi. Identify, by means of NIR spectroscopy, a sheet of polymer different from P2 from the portion (F6) of the sheet rich in polymer P2 separated in step v, and separate the portion (F8) of the sheet rich in polymer different from P2 from the portion (F6) of the sheet rich in polymer P2 by means of a suitable separation method.

[0024] Preferably, the above method further includes the following steps:

[0025] vii. Identify the polymer P3 flakes from the portion (F2) of the sheet rich in black plastic material separated in step ii by mid-infrared (MIR) spectroscopy, and separate the portion (F9) of the polymer P3-rich flakes from the portion (F2) of the sheet rich in black plastic material by a suitable separation means, thereby obtaining the portion (F10) of the sheet poor in polymer P3.

[0026] viii. Identify a polymer different from P3 from the portion (F9) of the polymer P3-rich sheet separated in step vii by MIR spectroscopy, and separate a portion (F11) of the polymer different from P3 from the portion (F9) of the polymer P3-rich sheet by a suitable separation means.

[0027] ix. The polymer P4 sheet is identified by MIR spectroscopy from the portion (F10) of the sheet separated in step vii containing polymer P3 and from the portion (F11) of the sheet separated in step viii containing a polymer different from P3, and the portion (F12) of the polymer P4 sheet is separated from the portion (F2) of the sheet containing black plastic material by a suitable separation means, thereby obtaining the portion (F13) of the sheet containing polymer P4.

[0028] x. Identify flakes of a polymer different from P4 from the fraction (F12) of flakes rich in polymer P4 separated in step ix by MIR spectroscopy, and separate fractions (F14) of flakes rich in a polymer different from P4 from said fraction (F12) of flakes rich in polymer P4 by suitable separation means.

[0029] In this way, a method is provided that can also separate black polymers (which are often difficult to identify and separate, given that the color of black polymers prevents them from being correctly read using NIR spectroscopy).

[0030] Preferably, the method according to the invention includes the step of separating and removing any ferrous and non-ferrous metallic materials from the sheet of plastic material before performing the identification and separation in step ii.

[0031] In this way, other foreign matter in the plastic material is removed, which may reduce the final purity of the polymer and thus damage the machine (e.g., an extruder used to recycle the plastic after the selection and separation described above).

[0032] Preferably, the method according to the invention includes a step of grinding commercial and / or industrial plastic waste to obtain the material in sheet form with a size range of 6 mm to 100 mm.

[0033] In this way, plastic materials are prepared to allow for the correct and efficient selection and separation of various components to obtain separated polymer materials with a purity of over 95%, making them directly usable for the recycling of plastic materials.

[0034] Preferably, the method according to the present invention includes the following steps:

[0035] xi. Identify polymer P5 sheets from the portion (F7) of the polymer P2-poor sheet separated in step v and the portion (F8) of the polymer-rich sheet different from P2 separated in step vi by NIR spectroscopy, and separate the portion (F15) of the polymer P5-rich sheet from the portion (F7) and the portion (F8) to obtain the portion (F16) of the polymer P5-poor sheet;

[0036] xii. Identify flakes of polymers different from P5 from the fraction of flakes rich in polymer P5 separated in step xi by NIR spectroscopy, and separate fractions rich in polymers different from P5 from said fraction of flakes rich in polymer P5 by suitable separation means (F17).

[0037] In this way, a method is provided that can separate more than two polymers from a mixture of polymers derived from commercial and / or industrial plastic waste.

[0038] Preferably, the method according to the invention includes the following additional steps: identifying the color of the polymer flakes separated in the foregoing steps by UV / VIS spectroscopy, and separating portions of the polymer flakes rich in a uniform color by a suitable separation means.

[0039] In this way, portions of a single-material polymer with a consistent color are obtained, which can be used directly or in the recycling process of plastic materials used to produce high-quality items.

[0040] Preferably, the method according to the invention includes the following additional steps: identifying flakes of one of the polymers P1, P2, or P5 based on the polymer's melt flow index using NIR spectroscopy, and separating the polymer-rich phase using suitable separation means.

[0041] In this way, a method is provided that can separate HDPE (high-density polyethylene) from LDPE (low-density polyethylene).

[0042] Preferably, the method according to the invention includes, after the foregoing steps of identifying and separating the phase rich in the polymer, an additional step of washing the sheets of polymers P1 and P2, polymers P3 and P4 if necessary, and polymer P5 if necessary.

[0043] In this way, a final product free of impurities and contaminants is obtained, which can be directly used in subsequent material recycling steps without altering the quality of the polymer, and therefore without changing the quality of the products made from these polymers.

[0044] Preferably, according to the method of the present invention, in the identification and separation steps, the surface distribution range of the material to be identified and separated is 1 kg / cm² per reading unit. 2 Up to 20kg / cm 2 .

[0045] This ensures the proper positioning of the flakes as they undergo identification via NIR or MIR spectroscopy to obtain separated polymer materials with a purity greater than 95%.

[0046] Preferably, the method according to the invention provides separation of the polymer by means of a jet of compressed air.

[0047] In this way, a high workflow and optimal separation of the selected polymer can be achieved.

[0048] According to the present invention, polymers P3 and P4 may be of the same or different chemical types as polymers P1 and P2 selected and separated in the foregoing steps. In other words, polymers P3 and P4 may be the same polymers P1 and P2, but selected and separated from the mixture of black polymer flakes. Detailed Implementation

[0049] The method according to the invention will now be described with reference to a preferred, non-limiting embodiment of the method.

[0050] The method according to the invention can be implemented using machines already used in industry, such as conveyor belts, loading hoppers, etc., as will be described below.

[0051] The method according to the invention can be applied to the selection and separation of various polymers, such as polypropylene (PP), polystyrene (PS), polyethylene (PE), high-density polyethylene and low-density polyethylene (HDPE, LDPE), polyethylene terephthalate (PET), polyvinyl chloride (PVC), acrylonitrile-butadiene-styrene (ABS), or others.

[0052] The method according to the invention is carried out in the process of mechanically selecting and separating polymers as described below. In particular, a method for separating three different polymers from a polymer mixture will be described.

[0053] The process described below refers to the selection of polyethylene (PE), polystyrene (PS), and polypropylene (PP) from a mixture of polymers derived from plastic waste.

[0054] The polymers are arbitrarily selected to allow for a better understanding of the separation method according to the invention, and therefore should not be considered as a limitation or reduction of the method.

[0055] A mixture of polymers derived from commercial and / or industrial plastic waste, preferably from which any non-polymeric organic or inorganic materials have been removed, is fed into a grinder capable of grinding the material to obtain approximate dimensions ranging from 6 mm to 100 mm or approximately 6 mm in diameter. 2 Up to 100mm 2The surface of the material is a sheet of plastic material. Preferably, the size of the ground material sheet is 15 mm to 80 mm to obtain a sheet that can be easily selected and separated by suitable selection and separation means described below.

[0056] A sheet of plastic material is conveyed via a suitable conveyor belt to a device where any ferrous metals present in the polymer mixture are eliminated using neodymium magnets. The sheet is then conveyed to a second device where any non-ferrous metals present in the polymer mixture are eliminated using eddy currents.

[0057] Then, a polymer mixture that is essentially free of metals is deposited onto the conveyor belt to achieve a concentration in the range of 1 kg / cm² on the belt. 2 Up to 20kg / cm 2 The preferred range is 3 kg / cm². 2 Up to 10kg / cm 2 The surface distribution of the material. In this way, the slices will be optimally distributed, avoiding any overlap of slices that would invalidate subsequent selection by optical instruments. The material distribution can be defined as the surface distribution of each reading unit.

[0058] The material, thus distributed, is fed to a selection device, where a sheet of colored or white plastic material is identified relative to a sheet of black plastic material using near-infrared (NIR) spectroscopy.

[0059] According to the present invention, the term colored means a material that absorbs all electromagnetic radiation incident on the visible field except for radiation having a wavelength relative to the color referred to.

[0060] According to the present invention, the term white (or achromatic color) refers to a material capable of reflecting all electromagnetic radiation incident on the visible field.

[0061] According to the present invention, the term black refers to an object that absorbs all electromagnetic radiation incident on the visible field without reflecting it. Black corresponds to the visual impression experienced when no visible light reaches the eye.

[0062] As is known in the art, NIR (near-infrared) spectroscopy is a spectral absorption technique that utilizes electromagnetic radiation in the near-infrared spectrum (i.e., wavelengths ranging from 780 nm to 2500 nm).

[0063] Using NIR spectroscopy, materials with different properties can be selected based on the selective absorption of infrared radiation by different plastic materials.

[0064] Because the black pigment present in the plastic material absorbs infrared light, making the material "invisible" to the optical selector, the first device is able to select colored or white plastic materials by means of NIR spectroscopy.

[0065] Selected plastic materials are separated by jets of compressed air that impact the chosen material, i.e., materials identified by NIR spectroscopy, and thus sprayed onto different conveyor belts. Depending on the equipment setup, the jets of compressed air may also impact unselected materials, i.e., materials not identified by NIR spectroscopy.

[0066] The remaining plastic material is then transferred to different conveyor belts by gravity.

[0067] This separation step will be used for all selection and separation steps described below.

[0068] According to the present invention, other separation methods and steps not explicitly described in this specification may also be used.

[0069] After separation due to the jet of compressed air, there will be two parts of different plastic materials, one part F1 is rich in sheets of colored and white plastic materials, and the other part F2 is rich in sheets of black plastic materials.

[0070] The fraction F1, rich in colored and white plastic flakes, is then fed to a selection device where PE flakes are identified by NIR spectroscopy and separated by a jet of compressed air to form the fraction F3, which is rich in PE flakes. Similarly, the fraction F4, which is poor in PE flakes, is formed.

[0071] Fraction F3, rich in PE flakes, is fed back to a selection device where flakes of polymers different from PE are identified by NIR spectroscopy. These flakes are then separated by a jet of compressed air to form fraction F5, rich in polymers different from PE. The remaining PE flakes will have a purity of 95% or higher regarding PE.

[0072] The fraction F4, which is lean in PP flakes, and the fraction F5, which is rich in flakes of a polymer different from PE, are placed together on a single conveyor belt and conveyed to a selection device, where the PP flakes are identified by NIR spectroscopy and separated by a jet of compressed air to form the fraction F6, which is rich in PP flakes. Similarly, the fraction F7, which is lean in PP flakes, is formed.

[0073] The PP-rich fraction F6 is then fed back to a selection device, where flakes of polymers different from PP are identified by NIR spectroscopy. These flakes are then separated by a jet of compressed air to form fraction F8, which is rich in polymers different from PP. The remaining PP flakes will have a purity of 95% or higher regarding PP.

[0074] In order to select and separate different types of polymers from the portions of the black plastic material-rich flakes selected and separated in one of the aforementioned steps, a portion of F2 is fed to a selection device, wherein PE flakes are identified from the portion of F2 of the black plastic material flakes by MIR spectroscopy.

[0075] As is known in the art, MIR (mid-infrared radiation) spectroscopy is a spectral absorption technique that utilizes electromagnetic radiation in the mid-infrared spectrum (i.e., wavelength range of 2.5 μm to 25 μm).

[0076] After selecting and separating PE from fraction F2, fraction F9, which is rich in black PE, and fraction F10, which is poor in black PE, are obtained.

[0077] Fraction F9, rich in black PE flakes, is fed back to a selection device where flakes of polymers different from PE are identified by MIR spectroscopy. These flakes are then separated by a jet of compressed air to form fraction F11, rich in polymers different from PE. The remaining black PE flakes will have a purity of 95% or higher regarding PE.

[0078] A portion F10, which is deficient in black PE flakes, and a portion F11, which is rich in black flakes of a polymer different from PE, are placed together on a single conveyor belt and conveyed to a selection device, where the black PP flakes are identified by MIR photospectroscopy and separated by a jet of compressed air, thereby forming a portion F12 rich in black PP flakes. Similarly, a portion F13, which is deficient in black PP flakes, is formed.

[0079] Fraction F12, rich in black PP flakes, is fed back to a selection device where flakes of polymers different from black PP are identified by MIR (Medium-Intensity Reduction). These flakes are then separated by a jet of compressed air, forming fraction F14, which is rich in polymers different from PP. The remaining black PP polymer flakes will have a purity of 95% or higher regarding PP.

[0080] To separate additional types of polymers from a mixture of polymers derived from plastic waste, portions F7 and F8, as described above, are placed together on a single conveyor belt and conveyed to a selection device where PS flakes are identified by NIR spectroscopy. These flakes are then separated by a jet of compressed air to form portion F15, which is rich in PS flakes. Similarly, portion F16, which is poor in PS flakes, is formed.

[0081] The fraction F15, rich in PS flakes, is fed back to a selection device where flakes of polymers different from PS are identified by NIR spectroscopy. These flakes are then separated by a jet of compressed air to form fraction F17, which is rich in polymers different from PS. The remaining PS flakes will have a purity of 95% or higher regarding PS.

[0082] The previously selected and separated polyethylene flakes, including colored and white polyethylene flakes and black polyethylene flakes, can be further selected and separated through additional separation steps based on NIR or MIR spectroscopy. In fact, it is well known that the different average lengths (average molecular weights) of the PE polymer chains affect the NIR or MIR spectra of the polymer. Therefore, through additional NIR-based or MIR-based selection steps, higher molecular weight PE flakes (qualitatively characterized by a lower melt flow index) can be selected and separated from lower molecular weight PE flakes (qualitatively characterized by a higher melt flow index).

[0083] Specifically, the PE sheets are selected by NIR or MIR spectroscopy and separated by a jet of compressed air, as previously described.

[0084] The sheets, which were previously selected and separated according to the type of their constituent polymers, are then fed to a suitable grinding device to further reduce their size, thereby obtaining sheets of material with the size to be used immediately in plastic extrusion equipment.

[0085] These flakes are then fed to suitable washing equipment, where they are washed with water and, if necessary, with specific products to remove any residue of dirt or dust that may have formed in the selection and separation steps described above.

[0086] Previously separated, ground, and washed colored and white PE (HDPE and LDPE), PP, and PS flakes are conveyed to a continuous selection and separation device, in which the flakes are selected according to specific colors by UV / VIS spectroscopy and separated by a jet of compressed air.

[0087] As is known in the art, UV / VIS (ultraviolet / visible) spectroscopy is a spectral absorption technique that utilizes electromagnetic radiation in the ultraviolet / visible spectrum (i.e., wavelength range of 400 nm to 700 nm).

[0088] The method described in this invention allows for the selection and separation of an indeterminate number of different polymers. Therefore, this method can be applied to mixtures containing more than three polymers as described above without compromising selection and separation efficiency.

Claims

1. A method for mechanically selecting and separating at least two polymers from a mixture of polymers derived from commercial and / or industrial plastic waste, the method comprising the steps of: i. Providing a mixture of polymers derived from commercial and / or industrial plastic waste, consisting of sheets of the polymer in size from 6 mm to 100 mm; ii. Identify the sheets of colored and white plastic materials by near-infrared (NIR) spectroscopy, and separate the portion of the sheet rich in the colored and white plastic materials (F1) from the portion of the sheet rich in black plastic materials (F2) by a suitable separation method; iii. Identify the polymer P1 flakes from the portion (F1) of the flakes rich in colored and white plastic material separated in step ii by the NIR spectroscopy, and separate the portion (F3) of the polymer P1-rich flakes from the portion (F1) of the flakes rich in colored and white plastic material by a suitable separation means, thereby obtaining the portion (F4) of the flakes poor in polymer P1; iv. Identify a sheet of polymer different from P1 from the portion (F3) of the sheet rich in polymer P1 separated in step iii by the NIR spectroscopy, and separate a portion (F5) of the sheet rich in polymer different from P1 from the portion (F3) of the sheet rich in polymer P1 by a suitable separation means. v. Identify the polymer P2 sheet from the portion (F4) of the sheet separated in step iii containing polymer P1 and from the portion (F5) of the sheet separated in step iv containing a polymer different from P1 by the NIR spectroscopy, and separate the portion (F6) of the sheet rich in polymer P2 from the portion (F1) of the sheet rich in colored and white plastic materials by a suitable separation means, thereby obtaining the portion (F7) of the sheet containing polymer P2. vi. Identify, by means of the NIR spectroscopy, a sheet of polymer different from P2 from the portion (F6) of the sheet rich in polymer P2 separated in step v, and separate the portion (F8) of the sheet rich in polymer different from P2 from the portion (F6) of the sheet rich in polymer P2 by means of a suitable separation method.

2. The method according to claim 1, characterized in that... The method further includes the following steps: vii. Identify the polymer P3 flakes from the portion (F2) of the sheet rich in black plastic material separated in step ii by mid-infrared (MIR) spectroscopy, and separate the portion (F9) of the polymer P3-rich flakes from the portion (F2) of the sheet rich in black plastic material by a suitable separation means, thereby obtaining the portion (F10) of the sheet poor in polymer P3. viii. Identify, by means of the MIR spectroscopy, a sheet of polymer different from P3 from the portion (F9) of the sheet rich in polymer P3 separated in step vii, and separate the portion (F11) of the sheet rich in polymer different from P3 from the portion (F9) of the sheet rich in polymer P3 by means of a suitable separation method. ix. The polymer P4 sheet is identified from the portion (F10) of the sheet separated in step vii containing polymer P3 and from the portion (F11) of the sheet separated in step viii containing a polymer different from P3, and the portion (F12) of the sheet containing polymer P4 is separated from the portion (F2) of the sheet containing black plastic material by means of a suitable separation method, thereby obtaining the portion (F13) of the sheet containing polymer P4. x. Identify, by means of the MIR spectroscopy, a sheet of polymer different from P4 from the portion (F12) of the sheet rich in polymer P4 separated in step ix, and separate the portion (F14) of the sheet rich in polymer different from P4 from the portion (F12) of the sheet rich in polymer P4 by means of a suitable separation method.

3. The method according to claim 1 or 2, characterized in that... The method includes the steps of separating and removing any metallic material, encompassing both ferrous and non-ferrous metals, from the sheet of plastic material prior to the identification and separation in step ii.

4. The method according to claim 1 or 2, characterized in that... The method includes a milling step on commercial and / or industrial plastic waste to obtain the sheet material in the size range of 6 mm to 100 mm.

5. The method according to claim 1, characterized in that... The method further includes the following steps: xi. Identify polymer P5 sheets from the portion (F7) of the polymer P2-poor sheet separated in step v and the portion (F8) of the polymer-rich sheet different from P2 separated in step vi using the NIR spectroscopy, and separate the portion (F15) of the polymer P5-rich sheet from the portion (F7) and the portion (F8) to obtain the portion (F16) of the polymer P5-poor sheet; xii. Identify, by means of the NIR spectroscopy, a sheet of polymer different from P5 from the portion (F15) of the sheet rich in polymer P5 separated in step xi, and separate the portion (F17) of the sheet rich in polymer P5 from the portion of the sheet rich in polymer P5 by means of a suitable separation method.

6. The method according to claim 1 or claim 5, characterized in that... The method includes the following additional steps: identifying the color of the polymer flakes separated in claims 1 and 5 by UV / VIS spectroscopy, and separating portions of the flakes rich in the uniform color of the polymer by suitable separation means.

7. The method according to claim 1 or 2, characterized in that... The method includes an additional step of identifying flakes of one of polymers P1, P2, or P5 based on the average molecular weight of the polymer using NIR spectroscopy, and separating the polymer-rich phase using appropriate separation methods.

8. The method according to claim 1 or 2, characterized in that... The method includes, after the steps of identifying and separating the phase rich in the polymer, an additional step of washing the sheets of polymers P1 and P2, optionally polymers P3 and P4, and optionally polymer P5.

9. The method according to claim 1 or 2, characterized in that... The separation of the polymer is carried out by a compressed air jet.