Method for the continuous synthesis of polyoxazolines using a spiral tube reactor

Abstract

The invention relates to the continuous synthesis of polyoxazolines. A process for the continuous synthesis of polyoxazolines is protected, comprising the step... - Passing at least one oxazoline monomer through a helical tube reactor under the influence of heat, wherein the helical tube reactor has a spirally wound tube with an inner tube diameter and a diameter of the spiral winding, characterized in that: • the inner pipe diameter ranges from 4.5 mm to 34 mm, and • the lambda ratio, as the ratio of the pipe's inner diameter to the diameter of the spiral winding, lies in the range of 0.11-0.17, and • the spirally wound tube is a stainless steel tube, as well as the use of a helical tube reactor for the continuous synthesis of polyoxazolines, wherein the helical tube reactor comprises: a spirally wound tube with an inner tube diameter and a diameter of the spiral winding, characterized in that: • the inner pipe diameter ranges from 4.5 mm to 34 mm, and • the lambda ratio, as the ratio of the pipe's inner diameter to the diameter of the spiral winding, is in the range of 0.11-0.17, and • the spirally wound tube is a stainless steel tube.

Description

[0001] The invention relates to a process for the continuous polymerization of oxazolines to polyoxazolines (hereinafter referred to as poly(2-oxazolines)). These are also called poly(N-acetyleneimines) and consist of polymerized 2-oxazoline monomer units. It is known that oxazolines, in particular 2-substituted 2-oxazolines, can be polymerized to polyoxazolines in a cationic ring-opening, living polymerization. Batch processes, including, for example, microwave ovens, are possible and widespread. A disadvantage, however, is that the products vary slightly from batch to batch (also called batch-to-batch variation). Furthermore, batch sizes in batch processes are limited.

[0002] Coiled flow reactors have also been known for some time. Regardless of the polymerization mechanism, there is great interest on a large scale in further increasing the throughput of polymerization methods. Furthermore, polyoxazolines, for example, for medical applications, should have a dispersity of <1.5, preferably <1.3.

[0003] WO 2014 / 191171 A1 describes a continuous process for producing polyoxazolines in a tubular flow reactor containing a static mixer in the form of a "metal grid." Various advantages over known batch processes are cited. However, the only example cited yields only a polymer with a molecular weight of 4850 g / mol (corresponding to 30 repeat units, with a set number of 33 repeat units) and a high dispersity of 1.6. These results suggest that increased mixing in the tubular reactor occurs in the flow direction, leading to inhomogeneous polymers. The dispersity of this polymer would be insufficient for medical applications. WO 2017 / 182610 A1 describes a process for producing polymers from cyclic imino ethers, polyoxazolines, in a tubular reactor, for example, a wound tubular reactor, wherein the linear flow rate is at least 120 cm / min.A disadvantage is that in the tubular flow reactor without a mixing device, the polymer is not homogeneous despite comparatively very high flow rates. The dispersity is good at 1.10-1.20. The reactors used have only small internal diameters of 0.75 to 2.4 mm. It has been disclosed that with increasing pipe diameters in the present system, the dispersity increases independently of other parameters. As explained in Comparative Example 4 and calculated in Table 3 / line 2, the maximum lambda value is 0.06 – for PTFE as the pipe material, even a maximum of 0.027 (Table 3 / line 26). The lambda ratio is the ratio of the pipe's internal diameter to the diameter of the coils of the spiral pipe.

[0004] EP 2 719 452 A1 describes a spiral tube reactor with a very low lambda ratio of 0.03-0.1 in other contexts, such as crystallizations, emulsion polymerizations or heterogeneous catalysis.

[0005] CN212942950U describes a bundle of spiral reaction tubes in the context of a ring-opening polymerization.

[0006] CN1390240A describes the use of spiral reaction tubes in the context of the production of polyether polyols.

[0007] Reis et al. (2020) describe spiral tubular reactors for the synthesis of block copolymers using a modular design.

[0008] Continuous tubular reactors are therefore suitable for producing polyoxazolines with low dispersities, as they produce homogeneous products in the so-called “steady state” without interruption of production and, unlike in numerous examples from research, there can be no batch-to-batch differences.

[0009] To achieve very low dispersities, it is well known that a low degree of mixing in the flow direction is necessary. However, in a spiral tube reactor with flow, laminar flow is often present. This laminar flow leads to mixing in the flow direction due to the different flow velocities at the wall and the center of the tube.

[0010] Turbulent-flow tubular reactors are also used. However, these currently have very small diameters, in the range of <1 mm. Tubular reactors with such small diameters are not suitable for high product throughput, meaning they cannot be scaled up. Increasing the diameter is likely to result in the turbulent flow transforming into laminar flow. It is known that tubular reactors with diameters ≥1 mm are only capable of achieving laminar flow.

[0011] Furthermore, in turbulent flow tubular reactors, the residence times in the reactor are often too short to achieve complete conversion of the reactants, so that laminar, and consequently slower flow, tubular reactors have been used for living polymerization.

[0012] In summary, with known methods, when the pipe inner diameters are enlarged to obtain high throughputs (i.e., molar conversion per unit time), the mixing in the flow direction and consequently the dispersity of the resulting polymer increases.

[0013] The object of the invention is therefore to develop a new process for the large-scale, continuous production of polyoxazolines, with the highest possible conversion per unit time (throughput). At the same time, the process should allow for good and controllable properties of the resulting polyoxazoline. The polymer should be homogeneous and have a low dispersity in the range of <1.5, preferably <1.3. The helical tube reactor used should ensure thorough mixing of the mixtures flowing through it orthogonal to the flow direction, thus counteracting mixing in the flow direction by the laminar regime and be resistant to aggressive media.

[0014] The problem is solved by the features of the independent patent claims. Preferred embodiments are described by the dependent claims.

[0015] The invention relates to a process for the continuous synthesis of polyoxazolines, in particular poly(2-oxazolines), comprising the step - passing at least one oxazoline monomer (in a reaction mixture) through a helical tube reactor under the action of heat, comprising a spirally wound tube having an inner tube diameter and a diameter of the spiral winding (of the tube), characterized in that, • the inner diameter of the tube (of the spiral wound tube) is 4.5 mm to 34 mm, and • the lambda ratio as the ratio of the inner diameter of the tube to the diameter of the spiral winding is in the range of 0.11-0.17, and • the spiral wound pipe is a stainless steel pipe.

[0016] The spiral winding of the tube forms so-called coils of the spiral tube reactor.

[0017] According to the invention, the formed spiral (formed by the wound tube) has a constant diameter over the substantial part of the length of the spiral. This is called a spiral tube reactor. This constant diameter of the spiral corresponds to the diameter of the spirally wound tube according to the invention. This means that the spiral tube reactor does not form a cone shape, but rather a cylinder shape, although it is still possible for the diameter to change gradually – within the scope of the value defined according to the invention.

[0018] The “lambda ratio” is the ratio of the inner diameter of the tube to the diameter of the spiral winding.

[0019] In order to achieve the corresponding lambda ratio for the given pipe inner diameter, the diameter of the spiral windings could sensibly be in the range of 35 mm to 305 mm.

[0020] The invention further relates to the use of a spiral tube reactor in a process for the continuous synthesis of polyoxazolines (from a reaction mixture containing at least one oxazoline monomer), which comprises: a spirally wound tube having an inner tube diameter and a diameter of the spiral winding (of the spirally wound tube), characterized in that, • the pipe inner diameter is 4.5 mm to 34 mm, and • the lambda ratio as the ratio of the inner diameter of the pipe to the diameter of the spiral winding is in the range of 0.11-0.17, and • the spirally wound pipe is a stainless steel pipe; in particular also the use in the method according to the invention.

[0021] When used, it is advisable to pass at least one oxazoline monomer (in a reaction mixture) through the helical tube reactor under the influence of heat.

[0022] Statements concerning the procedure apply equally to the use and vice versa.

[0023] For the purposes of the invention, "at least one oxazoline monomer" does not mean at least a single molecule, but rather "monomers of at least one chemical structure," meaning explicitly many individual molecules. A monomer of one chemical structure would be, for example, 2-methyl-2-oxazoline, and one of another chemical structure would be, for example, styrene or 2-ethyl-2-oxazoline.

[0024] It is also explicitly stated that not the entire tube of a helical tube reactor needs to be spirally wound. However, "spirally wound tube" refers to the part that is spirally wound, although straight intermediate sections may also be provided.

[0025] In this context, it is also encompassed that there may be further pipes (also designed according to the invention).

[0026] Linear initial, final, or intermediate sections are also possible. Laminar flow can then also be present in these sections. These sections do not serve the main part of the polymerization, but may only serve as a post-reaction, allowing the final small amounts of monomer to react, or cooling the reaction mixture. In such a helical tube reactor according to the invention, however, at least 80% of the stainless steel tube sections are spirally wound.

[0027] It is also explicitly stated that only part of the tube is heatable, or that, if there are multiple tubes, not all of them are heatable. Generally, heating ensures that polymerization can take place at these points.

[0028] There is an important connection between the relatively large inner pipe diameters according to the invention and the homogeneous mixing required. A stabilization of the flow regime by a secondary flow (orthogonal to the primary flow) was observed. This secondary flow most likely stabilizes the laminar primary flow (primary flow in the pipe flow direction), allowing higher flow velocities while still maintaining good mixing while flowing through the helical tube reactor. Mixing in the flow direction, which leads to an increase in dispersity, is thus minimized. The residence time nevertheless appears to be long enough to enable complete oxazoline polymerization. If the residence time during flow is too short at the points exposed to heat, the polymerization is incomplete.For example, if a block copolymer is to be produced, it could happen that the first monomer is still present in the reaction mixture, so that after the addition of the second monomer, the block composed of the second monomer building blocks becomes contaminated with the first monomer building blocks, since these have not yet been consumed. If, however, the residence time is too long, side reactions occur more frequently, such as chain transfer through proton abstraction and subsequent initiation of new polymer chains by the resulting species.

[0029] The mixing in the flow direction, which leads to an increase in dispersity, is minimized by the invention.

[0030] The invention allows for the production of as much polyoxazoline in 5 minutes as would be possible with conventional batch syntheses in only 1 week. These syntheses are 1g-30g.

[0031] The invention makes it possible for the first time to produce polyoxazolines at a high (mass) throughput, namely from 6 mmol / min to 480 mmol / min, while simultaneously achieving good dispersity in the range 1.23-1.3 (as demonstrated in the three exemplary embodiments, here 41 mmol / min). The good dispersity is evidently based on sufficiently good mixing during passage through the helical tube reactor. In the prior art, however, when the tube inner diameters are enlarged to achieve high throughputs (i.e., mass conversion per unit time), mixing becomes insufficient, and the dispersity of the resulting polymer becomes high.

[0032] To achieve high throughputs with the pipe inner diameter according to the invention, high pressures are often required. The stainless steel material allows for the necessary pressure stability, but changes the possible minimum diameter of a spiral winding, which in turn changes the flow conditions and thus also the mixing and consequently the dispersity of the polymer.

[0033] The inventive combination of stainless steel with the mentioned tube inner diameters and the very large lambda ratio, which in turn specifies a small diameter of the spiral winding, is a surprisingly favorable spiral tube reactor design for the polymerization of oxazolines.

[0034] The stabilization of the laminar primary flow by a vortex-like secondary flow (orthogonal to the primary flow) in the spirally wound tube is one possible reason for the surprising results. In any case, the inventive design allows higher flow velocities (during the polymerization of polyoxazolines) than would be possible in laminar flow without this inventive geometry. The stainless steel withstands the high pressure that can occur at such high flow velocities. It is obvious that the geometry of a spirally wound tube and the resulting flow behavior depend significantly on the tube material.

[0035] The invention allows (for the synthesis of polyoxazolines) an optimal ratio between high yield per time and, at the same time, suppression of side reactions, which could occur, for example, due to excessively long residence times in the reactor under the influence of heat.

[0036] Advantageously, the tubular reactor according to the invention allows complete consumption of each oxazoline monomer present in the reaction mixture in the process according to the invention. The reaction mixture is the mixture that is passed through the tubular reactor in continuous operation with the aim of producing the polyoxazoline. At the same time, thorough mixing is achieved, which is fundamentally necessary to obtain a homogeneous polymer with a minimum dispersity of 1.0. This means that the polymer has as uniform a composition as possible in each molecule.

[0037] The resulting polyoxazoline polymer is also homogeneous.

[0038] As already indicated above, the invention advantageously allows for improved mass, heat, and energy transfer, thus increasing the conversion per unit time. A more homogeneous reaction mixture is achieved in the reactor, so that the polydispersity is <1.5, often even <1.3.

[0039] The pipe is preferably 2m to 5m long.

[0040] The relatively large inner diameter allows for the production of larger quantities per unit time, which consequently also reduces the proportion of labor costs in the product price. The invention is applicable on an industrial scale. Continuous operation allows the production of a polymer of defined and consistent quality.

[0041] The geometry according to the invention (this refers to the above-mentioned inner tube diameter and the lambda ratio for the stainless steel tube) also allows for a space-saving arrangement and thus a modular design. This means that if the helical tube reactor has several spirally wound tubes that are linearly and preferably separably connected to one another, the very simple production of copolymers, especially block copolymers, is possible.

[0042] The actual pitch of the spirals has no influence on the invention.

[0043] In a preferred embodiment of the invention, the inner diameter of the spirally wound tube is 6.35-38.1 mm, particularly preferably 8-12 mm, also 9-10 mm, in particular even 10 mm.

[0044] In a likewise preferred embodiment, the lambda ratio is 0.11-0.16.

[0045] It is also preferred if, in one embodiment of the invention, the diameter of the spiral winding is 50-300 mm, even 50-120 mm, particularly preferably 70-95 mm, in particular also 72 mm.

[0046] In one embodiment of the invention, the stainless steel tube (spirally wound tube) has a wall thickness of 0.9-2.2 mm, particularly 1-2.2 mm. This is optimal for achieving the inventive design of the helical tube reactor with this material. In a preferred embodiment, the lambda ratio is 0.13 ±0.01.

[0047] It is also a preferred version if the • Pipe inner diameter at 10mm ±1mm, and • the diameter of the spiral winding is 72mm ±7mm.

[0048] These are particularly favorable parameters for the spiral-wound stainless steel pipe to stabilize the laminar primary flow.

[0049] In this embodiment, the wall thickness (of the spirally wound tube) is most preferably 1mm ±0.2mm, better 0.9-1.1mm.

[0050] In a preferred embodiment of the invention, the monomer throughput when passing the oxazoline monomer through the spirally wound tube is between 6 and 480 mmol / min. Most preferably, the concentration of the oxazoline monomer at the beginning of the passage is 4 mol / L ±2.5 mol / L (preferably ±1.5 mol / L; in particular even 3-5 mol / L).

[0051] In this embodiment, it is particularly preferred if the flow of the oxazoline monomer when passing through the helical tube reactor according to the invention is 10 mL / min.

[0052] In another embodiment of the invention, the concentration of the oxazoline monomer at the beginning of the passage is 1-10 mol / L, in particular 3-5 mol / L.

[0053] It is also a preferred embodiment of the invention if the lambda ratio is 0.13 ±0.01 and the pressure during passage is 40 bar ±5 bar (or 39-41 bar).

[0054] This advantageously achieves the very best flow behavior in the (spirally wound) stainless steel pipe according to the invention.

[0055] In a preferred embodiment, the temperature in the spirally wound tube during passage is 130-150°C. This range is particularly favorable for achieving complete polymerization of all oxazoline monomers at the high throughputs according to the invention. The temperature to be selected for the tube also depends on the internal diameter, with this range being an optimized one for the spiral tube reactor design according to the invention. The stainless steel also advantageously allows for more pressure to be applied, allowing more heat to be applied (i.e., a higher temperature of 130-150°C can be applied) without the reaction mixture boiling, depending on the solvent.

[0056] It is also a preferred embodiment if the lambda ratio is 0.13 ± 0.01, and the concentration of the oxazoline monomer during the passage is 4 mol / L ± 1.5 mol / L at the beginning of the passage, and the monomer flow rate of the oxazoline monomer during the passage is 6 to 480 mmol / min (preferably 50 mmol / min ± 5 mmol / min). In particular, this could be methyloxazoline.

[0057] In another preferred embodiment of the invention, during the passage, first a first oxazoline monomer and then a second oxazoline monomer different from the first are passed through the helical tube reactor, so that the polyoxazoline obtained is a block copolymer having at least two blocks.

[0058] Another preferred embodiment for block polymerization is designed such that the helical tube reactor has at least two spirally wound tubes and a monomer feed upstream of the first tube and between all tubes in the flow direction. This block construction is easily possible with the space-saving design of the helical tube reactor according to the invention.

[0059] It is also possible to have a monomer feeder between each tube.

[0060] The “first tube” refers to the first heated tube in which the polymerization is to take place.

[0061] Monomers of the same or different chemical structure can be introduced into the tubular reactor at these multiple monomer feeds. This arrangement is ideal for the production of block copolymers, with different monomer types being added at the different monomer feeds, thus forming polymer blocks.

[0062] In a variant of this design, all spirally wound tubes are the same length, so that depending on the length of the polymer block to be produced, a different number of consecutively arranged tubes (here without a monomer feed in between) are used. The length of a polymer block is thus controlled by the amount of monomer supplied (of the same chemical structure) and the number of subsequent tubes. Subsequently, a monomer of a different chemical structure, for example, can be added to the next monomer feed, which polymerizes onto the "growing polymer chain" in the subsequent tubes.

[0063] It is also preferred if the flow velocity during passage according to the invention is 0.1 - 1 cm / s, particularly preferably even 0.21 cm / s (±0.05 cm / s).

[0064] In a likewise preferred embodiment of the invention, the flow rate during passage is 9-11 mL / min and the inner tube diameter is 9-11 mm. The tube length is preferably 1 m (±10%).

[0065] The reaction mixture containing the at least one oxazoline monomer according to the invention and passed through the tubular reactor can expediently also contain an initiator capable of initiating the respective polymerization reaction. The same applies to terminating reagents capable of stopping the polymerization or terminating chain growth, whereby these are preferably used at the end of the tube in which the polymerization takes place, or only afterward.

[0066] The solvent in the process according to the invention, which is expediently added to the oxazoline monomer, i.e., which flows through the tubular reactor as part of the reaction mixture, is preferably a non-nucleophilic solvent. It is particularly preferably a polar, non-protic solvent, in particular selected from acetonitrile, chlorobenzene, chloroform, 1,2-dichlorobenzene, dichloromethane, dimethylformamide, dimethyl sulfoxide, and mixtures thereof, in particular a mixture of acetonitrile and chlorobenzene. As is known, other solvents such as methanol, ethanol, or water can also be used for termination, i.e., for terminating the polymerization at the end of the process according to the invention.

[0067] In one embodiment, the oxazoline monomer is methyl oxazoline.

[0068] Table 1 shows the batch sizes of three examples, each using methyloxazoline (MeOx) with the terminating reagent piperidine.

[0069] Table 2 shows the corresponding analytical results of the resulting polyoxazoline. Table 3 shows, in line 14, the spirally wound tube used in Examples 1 to 3 as a helical tube reactor. Furthermore, lines 2 and 26 show tube designs from the prior art, and the preferred embodiments of the invention are shown in lines 4-8, 13-20, and 22-24.

[0070] All embodiments can be combined with each other in any way. Examples of implementation Examples of implementation 1-3: High-throughput synthesis:

[0071] The initiator was weighed and dissolved in a mixture of 19 mL of dry chlorobenzene and 20 mL of dry acetonitrile. The calculated amount of 2-methyl-2-oxazoline (oxazoline monomer) was added to the solution. After mixing, 50 mL of the solution was pumped into a helical tube reactor.

[0072] The helical tube reactor had an inner tube diameter of 10 mm and the coils had a diameter of 72 mm.

[0073] The flow rate was 10 mL / min, the reactor temperature was between 130 and 150 degrees Celsius, and the pressure was 40 bar. After 30 to 35 minutes of flow, the product was collected in a bottle with a small amount of piperidine for 90 minutes. The resulting mixture was concentrated, taken up in methanol, and precipitated with a 15-fold excess of diethyl ether. The process was repeated, the product was dissolved in water, and freeze-dried. About the helical tube reactor used:

[0074] The inner diameter was 10 mm. The flow rate is calculated as follows: Radius r = 5 mm = 0.05 dm, cylinder volume: V = r^2 * pi * h, where h corresponds to the tube length and at h=1 m = 10 dm. V = 0.05 * 0.05 * 3.141 * 10 dm^3 = 78.5 ml → for a length of 1 m this results in 78.5 ml / m.

[0075] The flow rate was set to 10 mL / min. The calculated cylinder volume is: 0.1274 m / min = 12.74 cm / min = 0.212 cm / s

[0076] The monomer throughput is calculated as follows: m(monomer) = 21 g, M(monomer) = 85.1 g / mol, n(monomer) = 247 mmol V(solution: chlorobenzene + acetonitrile + monomer) = 19 ml + 20 ml + 21 ml = 60 ml c(Monomer) = 247 mmol / 60 ml = 4 mol / L 247 mmol in 60 ml solution 10 ml / min flow (in 5 minutes) → 247 / 5 mmol / min = 49.4 mmol / min. A safety margin is maintained to prevent air from entering the system.

[0077] The following Table 1 shows various implementation examples: Table 1 shows the batch sizes of three examples, each using methyloxazoline (MeOx) with the terminating reagent piperidine. Implementation example Connection m [g] n [mmol] eq. T [°C] 1 8 3,2587 7,1 1 150 MeOx 21,1050 248 35 Piperidine 2,4500 28,8 4 2 9 3,1026 6,96 1 140 MeOx 21,1050 248 36 Piperidine 2,4500 28,8 4 3 11 5,3600 4,14 1 140 MeOx 14,0700 165 20 Piperidine 2,4500 28,8 4 Table 2 shows the corresponding analytical results of the obtained polyoxazoline Implementation example Pn (theor.) Pn (NMR) Mn (NMR) [kg / mol] Pn (MALDI) Mn (MALDI) [kg / mol] Mn (GPC) [kg / mol] D (GPC) Yield [%] 1 35 39 3,8 35 3,4 2,5 1,3 69 2 36 35 3,4 36 3,4 3,2 1,32 83 3 20 30 3,1 19 2,2 2,3 1,25 70 Mn number average molecular weight Pn degree of polymerization D Dispersity of the polymer About the helical tube reactors used:

[0078] Table 3 shows in line 14 the spiral wound tube used in the embodiments 1 to 3 as a helical tube reactor. Table 3: Pipe designs. Lines 2 and 26 from the prior art. According to the invention in lines 4-8, 13-20, and 22-24. Outside diameter [inches] Outer diameter [mm] Wall thickness [inches] Wall thickness [mm] Inner diameter [inches] Inner diameter [mm] Bending radius [inches] Bending radius mm Diameter [mm] lambda comment 1 1 / 16 1,59 0,014 0,36 0,0345 0,8763 4,00 8,00 0,1095375 2 1 / 8 3,18 0,028 0,71 0,069 1,7526 9 / 16 14,29 28,58 0,061333333 Maximum value Uni Gent (lambda not specified in disclosure) 3 4 1 / 4 6,35 0,035 0,89 0,18 4,572 3 / 4 19,05 38,10 0,12 5 3 / 8 9,53 0,035 0,89 0,305 7,747 15 / 16 23,81 47,63 0, 162666667 6 1 / 2 12,70 0,035 0,89 0,43 10,922 1 1 / 2 38,10 76,20 0,143333333 7 5 / 8 15,88 0,065 1,65 0,495 12,573 1,81 45,97 91,95 0,136740331 8 3 / 4 19,05 0,065 1,65 0,62 15,748 2,2 55,88 111,76 0,140909091 9 1 25,40 0,083 2,11 0,834 21,1836 4 101,60 203,20 0,10425 10 1 1 / 4 31,75 0,083 2,11 1,084 27,5336 5 127,00 254,00 0,1084 11 1 1 / 2 38,10 0,095 2,41 1,31 33,274 6 152,40 304,80 0,109166667 12 13 10,00 1,00 8 36,00 72,00 0,111111111 14 12,00 1,00 10 36,00 72,00 0,138888889 Wegener system 15 15,00 1,00 13 46,00 92,00 0,141304348 16 16,00 1,00 14 46,00 92,00 0,152173913 17 18,00 1,20 15,6 55,00 110,00 0,141818182 18 20,00 1,20 17,6 67,00 134,00 0,131343284 19 22,00 1,20 19,6 67,00 134,00 0,146268657 20 25,00 1,80 21,4 82,00 164,00 0,130487805 21 28,00 1,80 24,4 112,00 224,00 0,108928571 22 30,00 2,00 26 112,00 224,00 0,116071429 23 32,00 2,00 28 126,00 252,00 0,111111111 24 38,00 2,20 33,6 152,00 304,00 0,110526316 25 26 10,00 1,00 8 150,00 300,00 0,026666667 additional example for PTFE hose Explanations for the calculations of pipe diameters, bending radii and lambda:

[0079] Table 3 shows the respective dimensions of the spiral-wound tubing according to the manufacturer's specifications, Swagelok. The units listed in the columns are decimal values ​​for measurements in mm and inches, except for the "Outer Diameter [inch]" and "Bend Radius [inch]" columns. In these exceptions, the dimensions are given in standard (imperial) fractions.

[0080] The goal was to achieve the largest possible lambda (inner diameter) / coil diameter. To achieve this, the inner diameter should be as large as possible, with a tight coil and a small coil diameter. Since the manufacturer specifies values ​​for each outer and inner radius, these lambda values ​​are easily reproducible.

[0081] It can be assumed that the respective bending radii for stainless steel with the corresponding wall thicknesses are similar for many manufacturers due to the material parameters. The lambda value was calculated from the manufacturer's specifications for the bending radii and inner radii. The coil diameter is twice the bending radius.

[0082] It is evident that lambda values ​​of 0.10–0.17 can be achieved at a minimal bending radius. However, this requires the pipes to be deliberately / intentionally bent to these bending radii. Comparative Example 4 - according to WO 2017 / 182610A1:

[0083] Table 3 shows in the second entry (line 2) the calculation of the maximum lambda value for the tubular reactor from WO2017 / 182610A1.

[0084] If these bending radii are not specified (as in the application from Ghent University, i.e., WO2017 / 182610A1), it must be assumed that the bending was done unintentionally. This is plausible, since pipes with outer diameters of 1 / 16" and 1 / 8", in particular, can be wound by hand. This results in a maximum lambda value of 0.06, derived from the data from Ghent University (inner diameters and bending radii from the examples in the disclosure).

[0085] Table 3 shows in line 26 a calculation of the maximum lambda value according to WO2017 / 1812610A1 for PTFE as pipe material.

[0086] However, since in WO2017 / 182610A1 a) PTFE with an even smaller lambda value of maximum 0.026 was specified as an additional material and b) no bending radius or winding diameter was specified, it can be assumed that the present disclosure was purely used to save space by winding. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO 2014 / 191171 A1

[0003] WO 2017 / 182610 A1 [0003, 0083, 0084, 0086] EP 2 719 452 A1

[0004] CN 212942950U

[0005] CN 1390240A

[0006] WO 2017 / 1812610A1

[0085]

Claims

[1] Process for the continuous synthesis of polyoxazolines comprising the step of passing at least one oxazoline monomer through a helical tube reactor under the action of heat, wherein the helical tube reactor has a spirally wound tube with an inner tube diameter and a diameter of the spiral winding, characterized by , that: • the pipe inner diameter is 4.5 mm to 34 mm, and • the lambda ratio as the ratio of the inner pipe diameter to the diameter of the spiral winding is in the range of 0.11-0.17, and • the spiral wound pipe is a stainless steel pipe. [2] The method of claim 1, wherein the lambda ratio is 0.13 ± 0.

01. [3] Method according to claim 2, wherein • Pipe inner diameter at 10mm ±1mm, and • the diameter of the spiral winding is 72mm ±7mm. [4] Method according to claim 3, wherein • the wall thickness of the spiral wound tube is 1mm ±0.2mm. [5] A process according to any one of claims 1 to 4, wherein the monomer throughput of the oxazoline monomer during the passage is 6 to 480 mmol / min. [6] The method according to claim 5, wherein the concentration of the oxazoline monomer at the beginning of the passage is 4 mol / L ±1.5 mol / L. [7] The method of claim 6, wherein the flow of the oxazoline monomer during the passage is 10 mL / min. [8] Method according to one of claims 1 to 7, wherein the lambda ratio is 0.13 ± 0.01, and the pressure during passage is 40 bar ± 5 bar. [9] Method according to one of claims 1 to 8, wherein the lambda ratio is 0.13 ±0.01, and when passing through, the concentration of the oxazoline monomer at the beginning of the passage is 4 mol / L ±1.5 mol / L, and when passing through, the monomer throughput of the oxazoline monomer is 6 to 480 mmol / min. [10] Process according to one of claims 1 to 9, wherein, during the passage, first a first oxazoline monomer and then a second oxazoline monomer different from the first is passed through the helical tube reactor, so that the polyoxazoline obtained is a block copolymer having at least two blocks. [11] Process according to one of claims 1 to 10, wherein the spiral tube reactor has at least two spirally wound tubes and has a monomer feed in front of the first tube and between all tubes in the flow direction. [12] Method according to one of claims 1 to 11, wherein the flow velocity during passage is 0.1 - 1 cm / s. [13] Method according to one of claims 1 to 6 or 8 to 12, wherein the flow during passage is 9-11 mL / min and the inner diameter of the tube is 9-11 mm. [14] Use of a spiral tube reactor for the continuous synthesis of polyoxazolines, wherein the spiral tube reactor comprises: a spirally wound tube with a tube inner diameter and a diameter of the spiral winding, characterized by , that: • the pipe inner diameter is 4.5 mm to 34 mm, and • the lambda ratio as the ratio of the inner diameter of the tube to the diameter of the spiral winding is in the range of 0.11-0.17, and • the spiral wound pipe is a stainless steel pipe.