Methods for polymer deposition

Abstract

The precipitant is provided in a precipitant reservoir (9) and the polymer solution is provided in a reservoir vessel (6). A precipitant pump (7) feeds the precipitant under pressure to a nozzle arrangement (4) to generate a free jet (1). The polymer solution arrives on the flat surface of the free jet (1) in the form of a continuous non-atomized polymer solution jet (2). At the impingement point (3) of the polymer solution jet (2), the average velocity difference between the precipitant stream and the polymer solution is more than one meter per second. Due to the corresponding shear forces at the impingement point (3), a good distribution of the polymer solution on the surface of the free jet (1) is achieved, as well as an immediate good mixing of the polymer solution with the precipitant. In the free jet (1), the polymer contained in the supplied polymer solution precipitates as solid polymer particles. The resulting mixture of precipitant, solvent and polymer solution is collected in a collection tank (11). In a centrifuge (13) or a filtration device, the polymer particles are separated from the liquid.

Description

[Technical Field]

[0001] The present invention relates to a method and apparatus for polymer deposition. [Background technology]

[0002] In general, the basic physical prerequisite for precipitation is the mixing of two liquids or liquid mixtures, whereby a substance dissolves or disperses in one liquid (or mixture) that is not soluble or dispersible in the other liquid (or mixture), or dissolves or disperses to a significantly lesser extent in the other. In a phase diagram of a three-substance mixture, a corresponding miscibility gap occurs in the range of the three substances that can precipitate. Precipitation can also be caused by a substance dissolved or dispersed in one liquid, causing the substance dissolved or dispersed in the other liquid to aggregate or agglomerate.

[0003] Polymer precipitation is a common method for separating polymers present in a liquid medium. Primarily, the polymer contained in a solvent or solvent mixture must be converted into a solid agglomerate, in particular in particulate form, and / or a polymer already present in particulate form must be separated from the suspension. Polymer precipitation is also used as a purification method, for example, to separate previously added reagents (e.g., smaller molecules) or impurities, or to separate polymer fragments or smaller chains.

[0004] The precipitated polymer, i.e. the polymer converted into a solid material of the desired consistency, is separated in a further step mechanically, for example by filtration and / or centrifugation, and / or thermally, i.e. by drying.

[0005] Precipitation occurs when a liquid in which the polymer to be precipitated is dissolved is added to a fluid in which the polymer is not soluble or only very slightly soluble (antisolvent, referred to in this application as a precipitant), provided that the temperature, concentration, volume, and addition rate are appropriately selected for polymer precipitation. The previously dissolved polymer precipitates in the form of solid particles. If the solvent of the polymer solution and the precipitant are immiscible or completely immiscible with each other, solids may form due to interactions at the interface.

[0006] During the precipitation of the polymer, it is also possible to remove impurities such as reactants, catalysts or short polymer chains that are more soluble in the precipitant than in the solvent of the polymer solution.

[0007] The purity of the resulting solid depends heavily on the process parameters selected. Differences in the concentration of the polymer solution can lead to nanoparticles, microparticles, or particles in the millimeter range. In the purification of polymers, an undesired particle size range can lead to significant drawbacks. Particles that are too small can still be present in suspension and must be separated from the suspension by further process steps, such as extraction. Furthermore, there can be a risk of undesired side reactions due to the large surface area. Also, in the case of separation by extraction, already separated components can be re-extracted during extraction by precipitation. On the other hand, particles that are too large can still contain solution inside them and thus become contaminated with the solvent and impurities contained in the particles.

[0008] Those skilled in the art know that some polymers are difficult or impossible to obtain in the desired purity by precipitation due to poor solubility, tendency to swell, or tendency to rapidly aggregate into solvent-contaminated, low-density masses during precipitation.

[0009] Another established method involves precipitating the polymer in low-temperature solvents such as ether or hexane at −80° C., but large amounts of water can condense and the method is difficult to scale up due to its high energy consumption.

[0010] Spray drying is another method for obtaining solid, non-dissolved polymers. This method differs from the others in that it does not involve purification by removing undesired substances dissolved in the solvent, but rather relies solely on solvent removal, which also involves concentration of impurities. Material losses, and especially energy consumption, are generally very high, and spray drying is only suitable for solvents with low boiling points or high vapor pressures.

[0011] On a laboratory scale, some polymer precipitations work easily in a beaker equipped with a stirring fish, into which a suitable precipitant is placed and the polymer solution is slowly added.

[0012] For larger scale polymer separation, for example, a large scale reactor is disclosed in WO 2014 / 207106 A1. Continuous flow systems are also known.

[0013] US Patent Application Publication No. 2012 / 245239 A1 and European Patent Application Publication No. 0462317 A2 describe high-pressure nozzle chambers, and WO 2008 / 035028 A1 discloses a turbulence chamber with counter-rotating rotors and spray drying.

[0014] U.S. Pat. No. 3,953,401 describes a method in which an atomized polymer solution is applied to a slowly moving precipitant surface, i.e., an agitated stream of precipitant placed in a stirred vessel, either to the surface of an open precipitant channel, or to a precipitant film continuing over the vessel wall.

[0015] Large-scale applications can be divided into two basic categories, each with its own advantages and disadvantages: on the one hand, completely closed systems such as continuous flow, high-pressure nozzle chambers, and turbulent chambers, and on the other hand, open large-scale reactors.

[0016] In closed systems, there is generally no gas-liquid phase boundary in the reaction chamber, making floating or levitation impossible, in contrast to open systems with a pre-existing gas-liquid phase boundary. In closed systems, the polymer solution is always added in the precipitation medium, which may limit the acceptable concentration range of the polymer solution depending on the polymer. For example, some polymers have a strong tendency to form large particles or filaments, which have strong adhesive properties and easily adhere to the edges or agitators of the reactor. To prevent adhesion or other adverse effects, for example, in Korean Patent Publication No. 20080051399 (A), several precipitating agents are also used simultaneously, which initially produces fine particles and then produces larger particles in a further step. However, this produces a solvent mixture that cannot be reused without further processing.

[0017] In open systems, the addition can also take place outside the liquid phase. In this case, obstacles such as the floating (floating) of the precipitated product or the formation of a cover layer on the surface of the precipitant must be overcome. The latter is particularly problematic, since after the formation of the cover layer, further precipitation of the polymer is significantly slowed or completely prevented. [Prior art documents] [Patent documents]

[0018] [Patent Document 1] International Publication No. 2014 / 207106 [Patent Document 2] US Patent Application Publication No. 2012 / 245239 [Patent Document 3] European Patent Application Publication No. 0462317 [Patent Document 4] International Publication No. 2008 / 035028 [Patent Document 5] U.S. Patent No. 3,953,401 [Patent Document 6] Korean Patent Publication No. 2008-0051399 Summary of the Invention [Problem to be solved by the invention]

[0019] Against this technical background, it is an object of the present invention to provide an alternative technique for separating polymers from polymer solutions, which at least partially avoids or mitigates the known drawbacks of conventional methods. [Means for solving the problem]

[0020] According to one aspect of the invention, this problem is solved by a method according to claim 1. According to a further aspect of the invention, this problem is solved by an apparatus according to claim 12. Advantageous embodiments of the invention can be implemented according to one of the dependent claims.

[0021] The present invention therefore provides, in particular, a method for polymer precipitation, in which a polymer solution is added to a precipitant stream, which is provided as a free jet, preferably emerging in a gaseous medium, in particular air, at the point where the polymer solution is added to the precipitant stream. According to the usual definition, in the context of the present invention, a free jet is understood to be a fluid flow from an opening into a free environment, i.e., in particular, a free environment without a wall boundary of the jet transverse to its flow direction (main direction of propagation).

[0022] According to the present invention, the polymer precipitates in a jet of precipitant. Due to the velocity difference between the precipitant and the polymer solution, the jet distributes the added polymer solution to the location where it was added. This effect is enhanced by the flow of surrounding fluids, especially air, which creates a free jet in the environment due to hydrodynamic effects. Due to the short diffusion path between the polymer solution and the precipitant, the solution droplets are placed directly in the precipitant and rapidly exchange the solvent and soluble impurities by diffusion. The solvent is completely removed from the polymer.

[0023] On the other hand, in conventional precipitation methods, the droplet size is difficult to change because it depends on the concentration and the solvent.

[0024] Thus, a simple, cost-effective method has been created that allows for good mixing of the precipitant and polymer solution, is easily scalable, and can be adapted to a wide range of boundary conditions through easily adjustable parameters such as the volumetric flow rates of the precipitant and polymer solution and the velocity of the free jet. According to the present invention, a very pure product is achieved in that the diffusion path between the polymer solution and the precipitant is short, as explained above.

[0025] The method according to the invention can be used not only for the purification of polymers after polymerization, but also for modifying the properties of the solid product: due to the large velocity difference between the polymer solution and the precipitant, swollen polymers that cannot normally be recovered by precipitation can also be converted into solids.

[0026] Furthermore, the method according to the present invention provides a new method for the continuous production of submicron to nanoparticles.

[0027] Another possible application of the process according to the invention is the separation of polymer blends by means of the shear forces that occur, especially when polymers or polymer blends containing fillers are to be separated from one another.

[0028] Another field of application of the method according to the invention is the expansion of polystyrene. Due to the high air input near the free jet, the polymer particles produced can have a particularly large surface and / or can have internal cavities.

[0029] Even polymers whose solvents are insoluble in the precipitant can be precipitated by the method according to the invention in a way that is surprising for those skilled in the art. As far as the precipitant is concerned, the skilled artisan is surprisingly not even limited to the use of liquids, but the method according to the invention can also be advantageously carried out using gaseous precipitants, such as steam or carbon dioxide, i.e., the method according to the invention can also be advantageously carried out using gaseous precipitants, such as steam or carbon dioxide. However, in many precipitation tasks in which the method according to the invention can be advantageously used, the coagulation state of the precipitant stream in the free jet will be liquid.

[0030] Preferably, the polymer solution is added to the precipitant stream in a non-atomized form, i.e., poured, dripped, or sprayed in the form of one or more liquid jets, rather than sprayed into a free jet. Therefore, less equipment is required than if atomization had to be provided. This avoids technical problems such as clogging of the atomization nozzle or uneven spraying. The shear forces acting on the surface of the free jet ensure sufficient distribution of the polymer solution, making atomization of the polymer solution unnecessary in most cases.

[0031] Particularly preferably, the free jet is advantageously generated as a flat jet, for example, by a flat jet nozzle or a flat nozzle, or by a configuration of two or more nozzles arranged side by side. In this context, a flat jet is considered to be a jet whose width in the area of ​​polymer solution addition in a first spatial direction perpendicular to the main direction of propagation of the free jet is at least twice, preferably at least four times, the width in a second spatial direction perpendicular to both the first and main directions of propagation of the free jet. Thus, the surface area of ​​the free jet on which the polymer solution can impinge is increased compared to an omnidirectional jet of the same precipitant flow. The main direction of propagation of the free jet is defined as the spatial direction perpendicular to the surface on which the volumetric flow rate of the precipitant is greatest.

[0032] According to a particularly advantageous embodiment, the mean velocity difference Δv between the precipitant stream and the polymer solution at the time of collision with the precipitant stream is greater than or equal to 1 meter per second, preferably greater than or equal to 3 meters per second. In this case, the mean velocity difference Δv at the time of collision is greater than or equal to the volumetric flow rate Q of the precipitant stream in the main direction of propagation of the precipitant stream. F The area A crossed by the precipitant flow perpendicular to the main direction of propagation of the precipitant flow at the median impingement position (in the numerator) and the median impingement position (in the denominator) F and the volumetric flow rate Q of the polymer solution that has not yet collided with the precipitant stream in the main direction of propagation of the precipitant stream (intramolecularly). P , and the area A through which the polymer solution flows perpendicular to the main direction of propagation of the precipitant flow at the central impingement location (denominator). Pand the second quotient formed from the equation. Therefore, Δv=Q F / A F -Q P / A P is.

[0033] The central impingement location is defined as the plane perpendicular to the main direction of propagation of the precipitant stream, where half of the polymer solution streams fed upstream and downstream of it encounter the precipitant stream. "Upstream" and "downstream" refer to upstream and downstream of the precipitant stream, respectively.

[0034] As a simplified design criterion in an advantageous embodiment, the difference between the average velocity of the precipitant stream as it leaves the nozzle and the average velocity of the polymer solution as it leaves the polymer solution outlet opening is selected to be at least 1 meter per second, preferably at least 3 meters per second, and the average velocity of the precipitant stream as it exits the nozzle is determined by the volumetric flow rate of the precipitant stream as it exits the nozzle and the crossed nozzle opening A. D The average velocity of the polymer solution when a polymer solution outlet opening is present is the quotient of the volumetric flow rate of the polymer solution when a polymer solution outlet opening is present and the area of ​​the crossed polymer solution outlet opening.

[0035] According to an advantageous embodiment, the Reynolds number Re at the outlet of the precipitant flow from the nozzle for forming the free jet is at least 2300, and the Reynolds number Re is such that Re=Q F / A D -d D / ν F The volumetric flow rate Q of the precipitant flow exiting the nozzle is F (numerator) and the area A of the nozzle opening through which the flow passes D The quotient of (denominator) and the minimum diameter d of the nozzle at the outlet D It is formed as the product of the quotient of the viscosity (numerator) and the dynamic viscosity F of the precipitant (denominator). In this way, a turbulent jet formation can be achieved, which particularly supports the mixing of the precipitant and polymer solution.

[0036] According to a further advantageous embodiment, the location of addition of the polymer solution is a gas-filled space with a gas pressure of less than 0.2 MPa, which allows the method to be carried out at atmospheric pressure without any technical effort.

[0037] According to an advantageous embodiment, the precipitant and the solvent in the polymer solution are selected so that the ratio of the maximum solubility of the polymer in the precipitant of the precipitant stream to the concentration of the polymer in the solvent contained in the polymer solution is at least 10 times, preferably 25 times, particularly preferably at least 100 times smaller than the volumetric flow rate of the solvent when the polymer solution is added and the volumetric flow rate of the precipitant stream.

[0038] According to a particularly preferred embodiment, the main direction of propagation of the free jet at the outlet from the nozzle is inclined downwards at an angle of at least 20 degrees and at most 70 degrees, preferably at least 35 degrees and at most 55 degrees, to the horizontal.

[0039] The present invention also provides a polymer precipitator including a precipitant supply device for supplying a precipitant, a nozzle device for generating a free jet from the supplied precipitant, and an addition device for adding a polymer solution to the free jet.

[0040] According to an advantageous embodiment, the nozzle device comprises a flat-jet nozzle or flat nozzle. A flat nozzle is understood to mean that the nozzle, in particular its outlet opening transverse to the outlet opening, is at least twice as wide as it is high, preferably at least four times as wide as it is high. In other words, the maximum transverse extent of the surface spanned by the boundary of the nozzle's outlet opening is at least twice as large, preferably at least four times as large as the transverse extent of this surface perpendicular to its maximum transverse extent. Also understood as a flat nozzle is a nozzle having at its outlet a notch or groove that opens out in two opposite directions transverse to the main outlet direction, the notch or groove being at least twice as wide, preferably at least four times as wide, in its projection in the main outlet direction, as its height. In other words, the maximum transverse extent of the notch or groove in its projection in the main outlet direction is at least twice as large, preferably at least four times as large, in its projection perpendicular to its maximum transverse extent.

[0041] According to a particularly preferred embodiment, the nozzle arrangement defines an outlet direction of the free jet which is inclined downwards at an angle of at least 20 degrees and at most 70 degrees, preferably at least 35 degrees and at most 55 degrees.

[0042] Preferably, the apparatus further comprises a collection device for collecting the mixture formed by adding the polymer solution, and a separation device, such as a centrifuge and / or a filtration device, for separating the precipitated polymer from the collected mixture.

[0043] The invention will now be explained in more detail, by way of example only, with reference to the accompanying schematic drawings, in which: the drawings are not to scale, and in particular, for the sake of clarity, the interrelationships of the individual dimensions partly correspond to the dimensional relationships in the actual technical implementation; although preferred embodiments have been described, the invention is not limited thereto.

[0044] In principle, any variant of the invention described or shown within the scope of this application may be particularly advantageous depending on the economic and technical conditions in the individual case. Unless stated to the contrary or as far as is technically feasible in principle, the individual features of the described embodiments are interchangeable or combinable with one another and with features known per se from the prior art.

[0045] The drawings show: [Brief explanation of the drawings]

[0046] [Figure 1] FIG. 2 is a flow diagram of a method associated with one embodiment of the present invention. [Figure 2] 1 shows in a schematic perspective view the geometric conditions at the point of addition of the polymer solution to the precipitant jet according to an embodiment of the invention. [Figure 3a] An example of a flat nozzle is shown in plan view. [Figure 3b] An example of a flat nozzle is shown in cross section at the cross section indicated by dashed line AA' in FIG. 3a. DETAILED DESCRIPTION OF THE INVENTION

[0047] In the drawings, corresponding elements are identified with the same reference numerals.

[0048] 1 shows a flow diagram of a method according to an embodiment of the invention. A precipitant, e.g., water, is provided in a precipitant reservoir 9, and a polymer solution, e.g., PLGA in acetone, is provided in a reservoir vessel 6. By means of a precipitant pump 7, which may be of a pump type conventional per se in the prior art, e.g., a centrifugal pump, the precipitant is fed under pressure from the precipitant reservoir 9 to a nozzle arrangement 4, generating a free jet 1. The medium surrounding the free jet, in which the precipitant is in a liquid state, is air.

[0049] The free jet is a flat jet whose extent transverse to the main direction of propagation 1 of the free jet and to gravity g is twice as large as its extent in the direction of gravity g, as shown in Figure 2. In the region of the free jet 1 there is a place 3 of addition of the polymer solution, which impinges on the flat side of the free jet 1 in the form of a continuous, non-atomized polymer solution jet 2. The addition device 5 can advantageously be a nozzle from which the polymer solution jet 2 exits under pressure, or simply a pipe opening from which the polymer solution jet 2 emerges under the force of gravity g.

[0050] The polymer solution is fed to the dosing device 5 by means of a feed pump 8. Here too, pump types known per se from the prior art can be used as feed pump 8, such as, for example, a peristaltic pump.

[0051] At the location 3 of impingement of the polymer solution jet 2 onto the free jet 1, more precisely at the intermediate impingement position M, the average velocity difference Δv between the precipitant stream and the polymer solution is greater than or equal to 1 meter per second.

[0052] Δv=Q F / A F -Q P / A P ≧1 m s -1

[0053] During the ceremony, Q F volumetric flow rate of the precipitant flow in the main direction of propagation H A F The region traversed by the precipitant flow perpendicular to the main direction H of propagation of the free jet 1 at the central impingement location M Q P is the volumetric flow rate of the polymer solution that has not yet impinged on the free jet 1 in the main direction of propagation H of the free jet, A P The area A crossed by the polymer solution jet 2 perpendicular to the main direction H of propagation of the free jet 1 at the central impingement position M P .

[0054] The intermediate impingement position M is defined as the plane perpendicular to the main direction H of propagation of the free jet 1, before and after which half of the polymer solution supplied per unit time impinges on the free jet 1, and the main direction H of propagation of the free jet 1 is understood to be the spatial direction perpendicular to the surface where the volumetric flow rate of the precipitant is greatest.

[0055] Due to the large differential velocity at the point of impingement 3 and the corresponding shear forces, the impinging polymer solution jet 2 is torn apart, resulting in a good distribution of the polymer solution on the surface of the free jet 1 and, at the same time, a good initial mixing of the polymer solution with the precipitant. Mixing can be further improved by making the jet flow as turbulent as possible. This can be achieved in particular if the Reynolds number at the outlet of the flat nozzle 4 is at least 2300.

[0056] Re=Q F / A D ·d D / ν F ≧2300

[0057] During the ceremony, Q F the volumetric flow rate of the precipitant leaving the flat nozzle 4, A D Area flowed through the nozzle opening, d D The minimum inner diameter of the flat nozzle 4 at the outlet, and ν F Dynamic viscosity of the precipitant, ν F .

[0058] A guard pan 10 is used to collect any precipitant, polymer or solvent lost by splashing or dripping in the area of ​​polymer solution addition.

[0059] In the free jet 1, the polymer contained in the supplied polymer solution is precipitated in the form of solid polymer particles by mixing the precipitant and solvent. The resulting mixture of precipitant, solvent, and precipitated polymer is collected in a collection tank 11. A suspension pump 12, which may be of a type known per se in the art, conveys the mixture to a centrifuge 13 or a filter device for solid-liquid separation, where the polymer particles and liquid are separated. In a dryer 14, the liquid residue can be thermally removed from the polymer particles, if necessary.

[0060] The precipitant from which the solvent has been removed in the separation device 15 can be recycled, i.e. recycled, and used again in the precipitant reservoir 9 .

[0061] Although Figure 1 shows diagrammatically a flat or slit nozzle with an essentially rectangular outlet, the outlet opening can also have rounded narrow sides, for example by being manufactured by squeezing an originally cylindrical or elliptical tube. Figures 3a and 3b show a flat jet nozzle with a notch 16 perpendicular to the cylindrical nozzle bore 17. In its projection perpendicular to the main outlet direction, a groove D D The maximum lateral extent of the perpendicular lateral extent d D This is 3.2 times the amount. [Example]

[0062] Example 1 To produce nanoparticles, 50 mg of polylactide-co-glycolide (PLGA) was dissolved in 2 ml of dimethyl sulfoxide (DMSO) and precipitated in water. The precipitant water was introduced as a free jet, exiting a flat-jet nozzle at an angle of approximately 45° to the horizontal (downward tilt) at a flow rate of approximately 400 ml / min into ambient air. The PLGA solution was applied to the precipitant stream in the direction of gravity from a vertically mounted cannula with a syringe pump at a flow rate of approximately 99 ml / hr. Some precipitant (approximately 0.5 L) was added to the precipitant stream collection tank to prevent it from drying out.

[0063] Particles are produced with a harmonic intensity average particle size (Z-average) of 89.5 nm as determined by dynamic light scattering, and a polydispersity index of 0.15. The zeta potential is -27 mV.

[0064] After the provided PLGA solution is used up, the nanoparticles contained in the collected precipitant are concentrated and purified by adding 5 ml of 3% polyvinyl alcohol solution by tangential flow filtration.

Claims

1. 1. A method for polymer precipitation in which a polymer solution (2) is added to a precipitant stream (1), comprising: the precipitant stream (1) is provided as a free jet emerging in a gaseous medium at a location (3) where the polymer solution (2) is added to the precipitant stream (1), the cohesive state of the precipitant stream in the free jet is liquid; the difference between the average velocity of the precipitant stream (1) as it leaves the nozzle (4) and the average velocity of the polymer solution (2) as it leaves the polymer solution outlet opening is equal to or greater than 1 meter per second; The average velocity of the precipitant stream (1) as it leaves the nozzle (4) is the volumetric flow rate Q of the precipitant stream (1) coming out of the nozzle (4). Ｆ and a nozzle opening A through which the precipitant flow passes. Ｄ is the quotient of the area of ​​and The average velocity of the polymer solution (2) when it leaves the polymer solution outlet opening is the volumetric flow rate Q of the polymer solution (2) when it leaves the polymer solution outlet opening. Ｐ and the area of ​​the polymer solution outlet opening through which the polymer solution flows.

2. 2. The method of claim 1, wherein the polymer solution (2) is provided unatomized at the point (3) of addition of the polymer solution (2) to the precipitant stream (1).

3. The method of claim 1 , wherein the free jet is generated as a flat jet.

4. the average differential velocity Δv between the precipitant stream (1) and the polymer solution (2) when colliding with the precipitant stream (1) is 1 meter per second or more; The mean differential velocity Δv is the volume flow rate Q of the precipitant flow (1) in the main direction (H) of propagation of the precipitant flow (1) in the collision situation. Ｆ and the area A through which the precipitant stream (1) flows perpendicular to the main direction of propagation (H) of the precipitant stream (1) at the central impingement location (M). Ｆ and a quotient formed from The volume flow rate Q of the polymer solution (2) that has not yet impinged on the precipitant stream (1) in the main direction of propagation (H) of the precipitant stream Ｐ and the area A through which the polymer solution flows perpendicular to the main direction of propagation (H) of the precipitant stream (1) at the central impingement location (M). Ｐ Δv=Q Ｆ / A Ｆ -Q Ｐ / A Ｐ is calculated according to the central impingement position (M) is defined as a plane perpendicular to the main direction of propagation (H) of the precipitant stream (1), upstream and downstream of which half of the polymer solution (2) fed per unit time impinges on the precipitant stream (1), 2. The method according to claim 1, wherein the main direction of propagation (H) denotes in each case a spatial direction perpendicular to a surface through which the volume flow rate QF of the precipitant flow (1) is highest.

5. the Reynolds number Re of the precipitant stream (1) at the outlet from the nozzle (4) for forming the polymer solution free jet is at least 2300; The Reynolds number Re is The volumetric flow rate Q of the precipitant stream (1) leaving the nozzle (4) Ｆ and the nozzle opening A through which the precipitant flow passes. Ｄ The quotient of the area of ​​and The minimum diameter d of the nozzle (4) at the outlet of the nozzle (4) Ｄ and the dynamic viscosity of the precipitant, ν Ｆ The quotient of Re = Q Ｆ / A Ｄ ・d Ｄ / ν Ｆ The method of claim 1 , wherein the product is formed according to:

6. 2. The method according to claim 1, wherein the location (3) of addition of the polymer solution is in a gas-filled space with a gas pressure of less than 0.2 MPa.

7. 2. The method of claim 1, wherein the ratio of the maximum solubility of the polymer in the precipitant of the precipitant stream to the concentration of the polymer in the solvent contained in the polymer solution (2) is at least 10 times smaller than the ratio between the volumetric flow rate of the solvent when the polymer solution (2) is added and the volumetric flow rate QF of the precipitant stream (1).

8. 2. The method according to claim 1, wherein the main direction of propagation of the free jet (1) at the outlet from the nozzle (4) is inclined downwards at an angle of at least 20 degrees and at most 70 degrees with respect to the horizontal.

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