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EP-4735226-A1 - METHOD OF EXTRUDING A WATER-CONTAINING POLYMER

EP4735226A1EP 4735226 A1EP4735226 A1EP 4735226A1EP-4735226-A1

Abstract

A method for extruding a polymer comprises the steps: a. providing, in an extruder, a particulate polymer starting material, the particulate polymer starting material comprising a polymer and water; b. extruding, using the extruder, the provided polymer starting material through at least one nozzle of the extruder, thereby obtaining an extruded polymer material. The polymer of the polymer starting material is selected such that in a second heating curve of a differential scanning calorimetry measurement of the polymer, the measurement being according to DIN EN ISO 11357 and at a heating rate of 20 K/min, the highest end temperature T ef for a phase transition of the polymer is ≥ −60 °C and ≤ 110 °C. T ef is defined in accordance with DIN EN ISO 11357. The polymer starting material has a water content of ≥ 3 weight-% to ≤ 35 weight-% based on the total weight of the polymer starting material and the temperature of the extruded polymer material is ≥ 30 °C to ≤ 100 °C.

Inventors

  • FISCHER, ANNE
  • SCHUSTER, Fabian
  • ACHTEN, DIRK
  • BIJLARD-JUNG, Ann-Christin
  • TILLACK, JOERG
  • KOENIG, THOMAS
  • SCHMELZLE, Steffen

Assignees

  • Covestro Deutschland AG

Dates

Publication Date
20260506
Application Date
20240621

Claims (10)

  1. 1. A method for extruding a polymer comprising the steps: a. providing, in an extruder, a particulate polymer starting material, the particulate polymer starting material comprising a polymer and water; b. extruding, using the extruder, the provided polymer starting material through at least one nozzle of the extruder, thereby obtaining an extruded polymer material; characterized in that the polymer of the polymer starting material is selected such that in a second heating curve of a differential scanning calorimetry measurement of the polymer, the measurement being according to DIN EN ISO 11357 and at a heating rate of 20 K/min, the highest end temperature T e f for a phase transition of the polymer is > -60 °C and < 110 °C, T e f being defined in accordance with DIN EN ISO 11357: for a peak of the curve as the point of intersection of the interpolated virtual baseline and tangent drawn at the point of inflection of the far side of peak and for a step of the curve as the point of intersection of the extrapolated end baseline and a tangent drawn at the point of inflection of the step, the provided polymer starting material has a water content of > 3 weight-% to < 35 weight-% based on the total weight of the polymer starting material and the temperature of the extruded polymer material is > 30 °C to < 100 °C and wherein the extruded polymer material has a water content of > 50% to < 100% of the water content of the polymer material provided in step a and wherein the polymer is a polyurethane.
  2. 2. The method of claim 1, further comprising: c. granulating the extruded polymer material obtained in step b., thereby obtaining a granulated polymer material.
  3. 3. The method of claim 1 or 2, further comprising: d. drying the extruded polymer material obtained in step b. and/or the granulated polymer material obtained in step c.
  4. 4. The method of one of the preceding claims, wherein the extruded polymer material has a water content of > 55 % to < 98% of the water content of the polymer material provided in step a.
  5. 5. The method of one of the preceding claims, wherein the extrusion is performed at an extrusion pressure of > 3 bar to < 80 bar.
  6. 6. The method of one of the preceding claims, wherein the diameter of the at least one nozzle of the extruder is > 0,5 mm to < 6 mm.
  7. 7. The method of one of the preceding claims, wherein the mass throughput of extruded polymer material through the at least one nozzle of the extruder is > 1 kg/h per nozzle to < 100 kg/h per nozzle.
  8. 8. The method according to one of the preceding claims, wherein the polymer comprises internally hydrophilizing functional groups and/or the polymer material comprises externally hydrophilizing agents.
  9. 9. The method according to one of the preceding claims, wherein the polymer is a thermoplastic polyurethane, preferably a thermplastic polyester-based polyurethane.
  10. 10. The method according to one of the preceding claims, further comprising the steps before step a.: i. Providing an aqueous dispersion of the polymer; ii. Coagulating the aqueous dispersion; iii. Removing water from the coagulate such that a polymer starting material having a water content of > 3 weight-% to < 35 weight-%, based on the total weight of the polymer starting material, is obtained.

Description

Method of extruding a water-containing polymer The present invention relates to a method for extruding a polymer comprising the step of providing, in an extruder, a particulate polymer starting material, the particulate polymer starting material comprising a polymer and water and the method further comprising the step of extruding, using the extruder, the polymer starting material through at least one nozzle of the extruder at an extrusion pressure and at a temperature of the extruded material, thereby obtaining an extruded polymer material. Polymer dispersions can be freeze-coagulated in order to obtain the solid polymer material. For example, WO 2021/233749 Al discloses a method of manufacturing a solids- incorporating polymer comprising the steps of: I) providing an aqueous polymer dispersion, the dispersion comprising crystallizing polyurethane particles having a mean particle size of < 500 nm and further comprising inorganic particles; II) storing the dispersion of step I) at a temperature of < 0 °C until a precipitate is formed; III) Isolating the precipitate of step II) and IV) removing water from the isolated precipitate of step III), thereby obtaining a water- depleted precipitate. The disclosure also relates to a solid particulate composition which is obtainable by the method and the use of the composition as a build material in additive manufacturing processes, as a coating, an adhesive or as a rubber. WO 2019/158599 Al relates to a method for applying a meltable polymer above its decomposition temperature. In the experimental section the freezing of certain Dispercoll® U type polyurethane dispersions at -18 °C for 12 h, followed by filtering the precipitate, drying, sieving and extruding into a filament, is described. It is reported that the precipitate was dried in a drying cabinet with extractor suction at 30 °C over the course of 24 h. US 2016/280809 Al describes a continuous or semi-continuous freeze coagulation process for aqueous polymer dispersions, wherein said process comprises a freezing step and a solid-liquid separation step and is further characterized in that it comprises the further step of admixing water and/or water vapor between the freezing step and the solid-liquid separation step. It is reported that after passing through the solid-liquid separation step, the removed solid fraction (with residual moisture) may, in a preferred embodiment, be further processed directly under the optional admixture of further additives, in a compounding step, for example to perform an extrudate and/or a pellet material. Polymer slurries can be subjected to extruder-based dewatering processes. US 6,517,335 discusses an apparatus and method for dewatering an elastomeric polymer. More specifically, the discosure is directed to an apparatus and method for dewatering a slurry of water and/or other liquids and elastomeric polymer, (e.g., ethylene propylene diene monomer rubber (EPDM), ethylenepropylene rubber (EPR), butyl rubber, halogenated butyl rubber and the like) in which the slurry is extruded through the barrel of a dewatering extruder, while the extruder conditions are continuously adjusted to provide a predetermined moisture content to the dewatered extrudate based on a real-time measurement of the water or moisture content of the elastomeric polymer within the extruder barrel. By controlling the moisture content of the elastomeric polymer based on the water or moisture content within the extruder barrel, a more efficient process can be achieved, and thus, a superior finished elastomeric polymer product, can reportedly be provided. US 4,305,901 relates to a method of making elongate, extruded thermoplastic products comprising the steps of mixing together (1) thermoplastic resin, (2) fine inert material and (3) water, the quantities of such additives being such that from about 5% to about 60% of the solids is thermoplastic resin, from about 40% to about 95% of the solids is fine inert material and the amount of water is such that the mixture has an extrudable consistency, forcing the mixture through an opening in a machined extrusion die with a pressure of at least about 25 psi forming a uniform elongate extrusion of the extruded material, of a cross-section determined by said die cross-section, drying said elongate member and fusing said thermoplastic resin. The present invention has the object of providing a method for extruding a polymer where the extruded polymer can be further processed, in particular into granules, which does not or not significantly degrade the technical properties of the polymer and which exhibits a favorable time and energy profile over the prior art methods. Such a method is recited in claim 1. Advantageous embodiments are the subject of the dependent claims. They can be combined freely unless the context clearly indicates otherwise. Accordingly a method for extruding a polymer comprises the steps: a. providing, in an extruder, a particulate polymer starting mater