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WO2023016848A1 - Sinter powder (sp) comprising at least one polylactide and at least one polycaprolactone - Google Patents

Sinter powder (sp) comprising at least one polylactide and at least one polycaprolactone Download PDF

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Publication number
WO2023016848A1
WO2023016848A1 PCT/EP2022/071583 EP2022071583W WO2023016848A1 WO 2023016848 A1 WO2023016848 A1 WO 2023016848A1 EP 2022071583 W EP2022071583 W EP 2022071583W WO 2023016848 A1 WO2023016848 A1 WO 2023016848A1
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WO
WIPO (PCT)
Prior art keywords
sinter powder
powder
range
fibres
polylactide
Prior art date
Application number
PCT/EP2022/071583
Other languages
French (fr)
Inventor
Jordan Thomas KOPPING
Claus Gabriel
Original Assignee
Basf Se
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Basf Se filed Critical Basf Se
Publication of WO2023016848A1 publication Critical patent/WO2023016848A1/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/12—Powdering or granulating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y70/00—Materials specially adapted for additive manufacturing
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
    • C08L67/04—Polyesters derived from hydroxycarboxylic acids, e.g. lactones
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2367/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
    • C08J2367/04—Polyesters derived from hydroxy carboxylic acids, e.g. lactones
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2467/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
    • C08J2467/04—Polyesters derived from hydroxy carboxylic acids, e.g. lactones

Definitions

  • Sinter powder comprising at least one polylactide and at least one polycaprolactone
  • the present invention relates to a sinter powder (SP) comprising at least one polylactide (A), at least one polycaprolactone (B), optionally at least one additive (C) and optionally at least one reinforcer (D).
  • SP sinter powder
  • the present invention further relates to a method of producing a shaped body using the inventive sinter powder (SP), to a shaped body obtained by this method and to the use of the inventive sinter powder (SP) in a sintering method.
  • the present invention relates to a method of producing the sinter powder (SP) and to the use of at least one polycaprolactone (B) in a sinter powder (SP) comprising at least one polylactide (A) for improving the mechanical properties of shaped bodies made from said sinter powder (SP).
  • SLS selective laser sintering
  • Selective laser sintering is frequently too time-consuming for the production of a relatively large number of shaped bodies, and so it is possible to produce relatively large volumes of shaped bodies using high-speed sintering (HSS) or “multi-jet fusion technology” (MJF) from HP.
  • HSS high-speed sintering
  • MTF multi-jet fusion technology
  • Polylactide is a well-known thermoplastic polymer used primarily in bioplastic applications. It is obtained by polymerizing a mixture of L-lactic acid and D-lactic acid, yielding either an amorphous or a semi-crystalline polymer, based on the ratio of D- lactic acid to L-lactic acid.
  • PLA Polylactide
  • shaped bodies produced with pure PLA of a high L-lactic content show generally poor mechanical properties, are brittle and have low toughness.
  • the laser sintering characteristics of PLA powders along with incorporating additives or biomass blend components to improve the processability of PLA powders are described. However, only moderate improvements to the part flexibility is noted with significant loss to mechanical strength.
  • WO 2020/099236 A1 describes a polymer powder for use as build material for production of a three-dimensional object by layer-by-layer melting and solidification of the build material at the sites corresponding to the cross section of the three- dimensional object in the respective layer by the action of radiation, preferably by the action of NIR radiation, wherein the polymer powder comprises a dry blend of polymer- based particles and particles of an NIR absorber, wherein the NIR absorber comprises carbon black or is carbon black.
  • the polymer can be a polylactide.
  • WO 2018/173755 A1 describes a resin powder for producing a three-dimensional object, wherein the resin powder has a number-average equivalent circle diameter of 10 micrometers or greater but 150 micrometers or less, and wherein a median in an equivalent circle diameter-based particle size distribution of the resin powder is higher than the average equivalent circle diameter.
  • the resin can be polylactic acid.
  • US 2018/0178445 A1 discloses a method of manufacturing a three-dimensional product having uniform mechanical properties using an SLS 3D printer including the steps of: preparing a mixed powder material by mixing resin powder and glass bubbles, wherein the specific gravity of the glass bubbles is from about 0.8 to about 1.2 times that of the resin powder.
  • the resin powder may be polylactic acid.
  • thermoplastic polymer powder and the use thereof as material for selective laser sintering (SLS).
  • the polymer powder contains a partially crystalline polymer, an amorphous polymer and a compatibilizing agent, and optionally additional additives and/or auxiliary substances, wherein the partially crystalline polymer, the amorphous polymer and the compatibilizing agent are in the form of a polymer blend.
  • the thermoplastic polymer powder can comprise 10 to 89.9% by weight polylactide.
  • WO 2020/058313 A1 discloses a method for producing a three-dimensional component by selective laser sintering (SLS), wherein a processing temperature Tx is set in a build chamber, and a powder layer, consisting of a thermoplastic polymer powder, is provided in said build chamber.
  • the polymer powder contains a blend of a semicrystalline polymer, an amorphous polymer, and a polymer compatibilizer.
  • the polymer powder can comprise 20 to 79.9% by weight polylactide.
  • SP sinter powder
  • the sinter powder and the process should be as simple and inexpensive as possible to produce and carry out.
  • SP sinter powder
  • the sinter powder (SP) of the invention can be used efficiently in selective laser sintering methods, high-speed sintering methods and multijet fusion methods.
  • the shaped bodies obtained by these methods show improved mechanical properties compared to shaped bodies comprising pure polylactide, for example, an improved toughness without scarifying mechanical strength.
  • the sinter powder (SP) of the invention is elucidated in detail hereinafter.
  • the sinter powder (SP) comprises at least one polylactide as component (A), at least one polycaprolactone as component (B), optionally at least one additive as component (C), and optionally at least one reinforcer as component (D).
  • component (A) and “at least one polylactide” are used synonymously and therefore have the same meaning.
  • component (B) and “at least one polycaprolactone” are used synonymously in the context of the present invention and therefore have the same meaning.
  • component (C) and “at least one additive”, and “component (D)” and “at least one reinforcer” are also each used synonymously in the context of the present invention and therefore have the same meaning.
  • the sinter powder (SP) comprises 10% to 92.5% by weight of component (A), 7.5% to 30% by weight of component (B), 0% to 20% by weight of component (C), and 0% to 40% by weight of component (D), based in each case on the total weight of the sinter powder (SP).
  • the percentages by weight of components (A), (B), and optionally of components (C) and (D), typically add up to 100% by weight.
  • the present invention thus also provides a sinter powder (SP), wherein the sinter powder (SP) comprises
  • component (D) 0% to 40% by weight of component (D), based in each case on the total weight of the sinter powder (SP).
  • the sinter powder (SP) comprises particles. These particles have, for example, a median particle size (D50) in the range from 40 to 80 ⁇ m, preferably in the range from 45 to 75 ⁇ m, and more preferably in the range from 45 to 70 ⁇ m.
  • D50 median particle size
  • the sinter powder (SP) of the invention has, for example, a D10 in the range from 10 to 60 ⁇ m, a D50 in the range from 40 to 80 ⁇ m and a D90 in the range from 50 to 150 ⁇ m.
  • the sinter powder (SP) of the invention has a D10 in the range from 20 to 50 ⁇ m, a D50 in the range from 45 to 75 ⁇ m and a D90 in the range from 80 to 125 ⁇ m.
  • the present invention therefore also provides a sinter powder (SP) having a D10 in the range from 10 to 60 ⁇ m, a D50 in the range from 40 to 80 ⁇ m and a D90 in the range from 50 to 150 ⁇ m.
  • SP sinter powder
  • the present invention therefore also provides a sinter powder (SP) having a median particle size (D50) in the range from 40 to 80 ⁇ m.
  • SP sinter powder
  • D50 median particle size
  • the "D10” is understood to mean the particle size at which 10% by volume of the particles based on the total volume of the particles are smaller than or equal to D10 and 90% by volume of the particles based on the total volume of the particles are larger than D10.
  • the "D50” is understood to mean the particle size at which 50% by volume of the particles based on the total volume of the particles are smaller than or equal to D50 and 50% by volume of the particles based on the total volume of the particles are larger than D50.
  • D90 is understood to mean the particle size at which 90% by volume of the particles based on the total volume of the particles are smaller than or equal to D90 and 10% by volume of the particles based on the total volume of the particles are larger than D90.
  • the sinter powder (SP) is suspended in a dry state using compressed air or in a solvent, for example water or ethanol, and this suspension is analyzed.
  • the D10, D50 and D90 values are determined by laser diffraction using a Malvern Mastersizer 3000. Evaluation is by means of Fraunhofer diffraction.
  • the sinter powder (SP) typically has a melting temperature (T M(SP) ) in the range from 150 to 180°C.
  • the melting temperature (T M(SP) ) of the sinter powder (SP) is in the range from 170 to 180 °C.
  • the melting temperature (T M(SP) ) is determined in the context of the present invention by means of differential scanning calorimetry (DSC). Typically, a heating run (H1) and a cooling run (C) are measured, each at a heating rate/cooling rate of 20 K/min. This affords a DSC diagram.
  • the melting temperature (T M(SP) ) is then understood to mean the temperature at which the melting peak of the heating run (H1) of the DSC diagram has a maximum.
  • the present invention therefore also provides a sinter powder (SP), wherein the melting temperature (T M(SP) ) of the sinter powder (SP) is in the range from 150 to 180°C
  • the sinter powder (SP) typically also has a crystallization temperature (T c ) in the range from 70 to 130°C.
  • T c crystallization temperature
  • the crystallization temperature (T c ) of the sinter powder (SP) is in the range from 80 to 120°C and especially preferably in the range from 90 to 110°C.
  • the crystallization temperature (T c ) is determined in the context of the present invention by means of differential scanning calorimetry (DSC). As described above, this customarily involves measuring a heating run (H) and a cooling run (C). This gives a DSC diagram. The crystallization temperature (T c ) is then the temperature at the minimum of the crystallization peak of the DSC curve.
  • DSC differential scanning calorimetry
  • the sinter powder (SP) typically also has a glass transition temperature (T G ).
  • the glass transition temperature (T G ) of the sinter powder (SP) is, for example, in the range from 20 to 80°C, preferably in the range from 30 to 70°C and especially preferably in the range from 40 to 60°C.
  • the glass transition temperature (T G ) of the sinter powder (SP) is determined by means of differential scanning calorimetry. For determination, in accordance with the invention, first a first heating run (H1), then a cooling run (C) and subsequently a second heating run (H2) is measured on a sample of the sinter powder (SP). The heating rate in the first heating run (H1) and in the second heating run (H2) is 20 K/min; the cooling rate in the cooling run (C) is likewise 20 K/min. In the region of the glass transition of the sinter powder (SP), a step is obtained in the second heating run (H2) in the DSC diagram. The glass transition temperature (T G ) of the sinter powder (SP) corresponds to the temperature at half the step height in the DSC diagram. This process for determination of the glass transition temperature is known to those skilled in the art.
  • the sinter powder (SP) can be produced by any methods known to those skilled in the art.
  • the sinter powder (SP) is produced by grinding, by precipitation, by melt emulsification, by spray extrusion or by microgranulation.
  • the production of the sinter powder (SP) by grinding, by precipitation, by melt emulsification, by spray extrusion or by microgranulation is also referred to as micronization in the context of the present invention.
  • the sinter powder (SP) is produced by precipitation, components (A) and (B), and optionally (C) and (D), are usually mixed with a solvent, and component (A) and component (B) are dissolved in the solvent, optionally with heating, to obtain a solution.
  • the precipitation of the sinter powder (SP) is then carried out, for example, by cooling the solution, distilling off the solvent from the solution or adding a precipitating agent to the solution.
  • Grinding can be carried out by any method known to a person skilled in the art, for example, components (A) and (B), and optionally (C) and (D), are introduced in a mill and ground therein.
  • Suitable mills include all mills known to those skilled in the art, for example classifier mills, opposed jet mills, hammer mills, ball mills, vibratory mills or rotor mills such as pinned disk mills and whirlwind mills.
  • the grinding in the mill can likewise be effected by any methods known to those skilled in the art.
  • the grinding can take place under inert gas and/or while cooling with liquid nitrogen. Cooling with liquid nitrogen is preferred.
  • the temperature in the grinding is as desired; the grinding is preferably performed at liquid nitrogen temperatures, for example at a temperature in the range from -210 to -195°C.
  • the temperature of the components on grinding in that case is, for example, in the range from -40 to -10°C.
  • the components are first mixed with one another and then ground.
  • components (A) and (B) are in the form of granules before micronization.
  • components (C) and (D) may also be present in the form of granules.
  • the granulate can be spherical, cylindrical or elliptical, for example.
  • a granulate is used which comprises components (A) and (B), and optionally (C) and (D), premixed.
  • the method of producing the sinter powder then preferably comprises the steps of a) mixing components (A) and (B), and optionally (C) and/or (D):
  • SP sinter powder
  • step b) optionally at least one reinforcer, in an extruder to obtain an extrudate (E) comprising components (A) and (B), and optionally (C) and/or (D), b) pelletizing the extrudate (E) obtained in step a) to obtain a granulate (G) comprising components (A) and (B), and optionally (C) and/or (D), c) micronizing the granulate (G) obtained in step b) to obtain the sinter powder (SP).
  • the method of producing the sinter powder comprises the following steps: a) mixing components (A) and (B), and optionally (C) and/or (D):
  • (D) optionally at least one reinforcer, in an extruder to obtain an extrudate (E) comprising components (A) and (B), and optionally (C) and/or (D), b) pelletizing the extrudate (E) obtained in step a) to obtain a granulate (G) comprising components (A) and (B), and optionally (C) and/or (D), c1) micronizing the granulate (G) obtained in step b) to obtain a polylactide powder (PP), c2) mixing the polylactide powder (PP) obtained in step c1) with a free-flow aid to obtain the sinter powder (SP).
  • sinter powder (SP) comprises component (D)
  • a granulate is preferably used which comprises only components (A) and (B), and, optionally, component (C) premixed.
  • the at least one reinforcing agent (D) is then preferably added after the micronization step.
  • the method of producing the sinter powder then preferably comprises the steps of a) mixing components (A) and (B), and optionally (C):
  • (C) optionally at least one additive, in an extruder to obtain an extrudate (E1) comprising components (A) and (B), and optionally (C), b) pelletizing the extrudate (E1) obtained in step a) to obtain a granulate (G1) comprising components (A) and (B), and optionally (C), c) micronizing the granulate (G1) obtained in step b) to obtain a sinter powder (SP1), preferably by grinding, d) mixing the sinter powder (SP1) and component (D):
  • the process then preferably comprises the following steps: a) mixing components (A) and (B), and optionally (C): (A) at least one polylactide,
  • (C) optionally at least one additive, in an extruder to obtain an extrudate (E1) comprising components (A) and (B), and optionally (C), b) pelletizing the extrudate (E1) obtained in step a) to obtain a granulate (G1) comprising components (A) and (B), and optionally (C), c1) micronizing the granulate (G1) obtained in step b) to obtain a polylactide powder (PP1), preferably by grinding, c2) mixing the polylactide powder (PP1) obtained in step c1) with a free-flow aid to obtain a sinter powder (SP2), d) mixing the sinter powder (SP2) and component (D):
  • Suitable free-flow aids are, for example, silicas, amorphous silicon oxide or aluminium oxides.
  • a suitable aluminium oxide is, for example, Aeroxide® Alu C from Evonik.
  • a suitable amorphous silica is, for example, HDK N20 from Wacker.
  • a sinter powder in which the free-flow aid in step c2) is selected from silicas, amorphous silicon oxide and/or aluminium oxides.
  • the sinter powder (SP) comprises a free-flow aid
  • this is preferably added in process step c2).
  • the sinter powder (SP) comprises 0.02 to 1 % by weight, preferably 0.05 to 0.8% by weight and particularly preferably 0.1 to 0.6% by weight of the free-flow aid, in each case based on the total weight of the polylactide powder (PP) or (PP1), respectively, and the free-flow aid.
  • step c) For the grinding in step c) and in step c1), the previously described explanations and preferences with regard to the grinding apply accordingly.
  • a further object of the present invention is therefore also the sinter powder (SP), obtained by the process according to the invention.
  • SP sinter powder
  • component (A) is at least one polylactide.
  • component (A) and “at least one polylactide” are used synonymously and therefore have the same meaning.
  • “at least one polylactide” means either exactly one polylactide or mixtures of two or more polylactides.
  • component (A) is exactly one polylactide.
  • the at least one polylactide (A) is preferably obtained by polymerizing a mixture (M) of L-lactic acid and D-lactic acid, wherein the mixture (M) comprises at most 10% by weight, preferably at most 5% by weight, and most preferably at most 2% by weight, of D-lactic acid, based on the total weight of the mixture (M).
  • the present invention therefore, also provides a sinter powder (SP), wherein the at least one polylactide (A) is obtained by polymerizing a mixture (M) of L-lactic acid and D-lactic acid, wherein the mixture (M) comprises at most 10% by weight, preferably at most 5% by weight, and most preferably at most 2% by weight, of D-lactic acid, based on the total weight of the mixture (M).
  • SP sinter powder
  • the at least one polylactide (A) has a melting temperature (T M(A) ) in the range from 150 to 180°C, more preferably in the range from 170 to 180°C, determined as described above.
  • T M(A) melting temperature
  • the present invention therefore, also provides a sinter powder (SP), wherein the melting temperature (T M(A) ) of the at least one polylactide (A) is in the range from 150 to 180°C.
  • SP sinter powder
  • the at least one polylactide (A) typically also has a crystallization temperature (T C(A) ) in the range from 70 to 130°C.
  • T C(A) crystallization temperature
  • the crystallization temperature (T C ⁇ A )) of the at least one polylactide (A) is in the range from 80 to 120°C and especially preferably in the range from 90 to 110°C.
  • the crystallization temperature (T C ( A )) is determined in the context of the present invention by means of differential scanning calorimetry (DSC). As described above, this customarily involves measuring a heating run (H) and a cooling run (C). This gives a DSC diagram. The crystallization temperature (T c ) is then the temperature at the minimum of the crystallization peak of the DSC curve.
  • the at least one polylactide (A) preferably has a relative viscosity in the range from 2.0 to 4.0, more preferably in the range from 2.5 to 3.5, measured at 1.0 g/dL in chloroform at 30°C according to ASTM D5225.
  • the at least one polylactide (A) preferably has a specific gravity in the range from 1.0 to 1.5 g/cm 3 , more preferably in the range from 1.1 to 1.4 g/cm 3 , determined according to ASTM D792.
  • the at least one polylactide (A) preferably has a melt index in the range from 20.0 to 30.0 g/10 min at 2,16 kg and 210 °C, more preferably in the range from 22.0 to 28.0 g/10 min at 2,16 kg and 210 °C, determined according to ASTM D1238.
  • the present invention therefore, also provides a sinter powder (SP), wherein the at least one polylactide (A) has i) a relative viscosity in the range from 2.0 to 4.0, and/or ii) a specific gravity in the range from 1.0 to 1.5 g/cm 3 , and/or iii) a melt index in the range from 20.0 to 30.0 g/10 min.
  • SP sinter powder
  • polylactide is the polylactide IngeoTM Biopolymer 6100D obtainable from NatureWorks.
  • component (B) is at least one polycaprolactone.
  • component (B) and “at least one polycaprolactone” are used synonymously and therefore have the same meaning.
  • “at least one polycaprolactone” means either exactly one polycaprolactone or mixtures of two or more polycaprolactones.
  • component (B) is exactly one polycaprolactone.
  • the at least one polycaprolactone (B) has a melting temperature (T M(B) ) in the range from 55 to 65°C.
  • Suitable polycaprolactones (B) have a mean molecular weight (M (B) ) in the range from 30 000 to 70 000 g/mol, and preferably in the range from 40 000 to 60 000 g/mol.
  • the at least one polycaprolactone (B) preferably has a melt flow index in the range from 5.5 to 8.5 g/10 min at 2.16 kg and 160°C.
  • An example of a suitable polycaprolactone is the polycaprolactone CapaTM 6500 obtainable from Ingevity.
  • the use of the at least one polycaprolactone (B) in a sinter powder (SP) comprising at least one polylactide (A) improves the mechanical properties of shaped bodies made from said sinter powder (SP).
  • the present invention therefore also provides the use of at least one polycaprolactone
  • sinter powder comprising at least one polylactide (A) for improving the mechanical properties of shaped bodies made from said sinter powder (SP).
  • Component (C) is at least one additive.
  • At least one additive means either exactly one additive or a mixture of two or more additives.
  • the at least one additive is selected from the group consisting of antinucleating agents, stabilizers, conductive additives, end group functionalizers, dyes, antioxidants (preferably sterically hindered phenols, and phosphites as secondary stabilizers), nucleating agents and colour pigments.
  • the present invention therefore also provides a sinter powder (SP) in which component
  • (C) is selected from the group consisting of antinucleating agents, stabilizers, conductive additives, end group functionalizers, dyes, antioxidants, nucleating agents and colour pigments.
  • Suitable antinucleating agent is lithium chloride.
  • Suitable stabilizers are, for example, phenols, phosphites and copper stabilizers.
  • Suitable conductive additives are carbon fibres, metals, stainless steel fibres, carbon nanotubes and carbon black.
  • Suitable end group functionalizers are, for example, terephthalic acid, adipic acid and propionic acid.
  • Suitable dyes and colour pigments are, for example, carbon black and iron chromium oxides.
  • Suitable nucleating agents are talcum or D-Lactide.
  • Suitable antioxidants are, for example, Irganox® 245, Irganox® 1076, Irganox® B900, Irganox® 1098 and Irgafos® 168 from BASF SE or Weston® TNPP phosphite from Addivant.
  • the sinter powder comprises component (C), it comprises at least 0.1% by weight of component (C), preferably at least 0.2% by weight of component (C), based on the sum total of the proportions by weight of components (A), (B), (C) and (D), preferably based on the total weight of the sinter powder (SP).
  • any component (D) present is at least one reinforcer.
  • At least one reinforcer means either exactly one reinforcer or a mixture of two or more reinforcers.
  • a reinforcer is understood to mean a material that improves the mechanical properties of shaped bodies produced by the process of the invention compared to shaped bodies that do not comprise the reinforcer.
  • Component (D) may, for example, be in spherical form, in platelet form or in fibrous form.
  • the at least one reinforcer is in platelet form or in fibrous form.
  • a “fibrous reinforcer” is understood to mean a reinforcer in which the ratio of length of the fibrous reinforcer to the diameter of the fibrous reinforcer is in the range from 2:1 to 40:1, preferably in the range from 3:1 to 30:1 and especially preferably in the range from 5:1 to 20:1 , where the length of the fibrous reinforcer and the diameter of the fibrous reinforcer are determined by microscopy by means of image evaluation on samples after ashing, with evaluation of at least 70 000 parts of the fibrous reinforcer after ashing.
  • the length of the fibrous reinforcer in that case is typically in the range from 5 to 1000 ⁇ m, preferably in the range from 10 to 600 ⁇ m and especially preferably in the range from 20 to 500 ⁇ m, determined by means of microscopy with image evaluation after ashing.
  • the diameter in that case is, for example, in the range from 1 to 30 ⁇ m, preferably in the range from 2 to 20 ⁇ m and especially preferably in the range from 5 to 15 ⁇ m, determined by means of microscopy with image evaluation after ashing.
  • the at least one reinforcer is in platelet form.
  • "in platelet form” is understood to mean that the particles of the at least one reinforcer have a ratio of diameter to thickness in the range from 4:1 to 10:1 , determined by means of microscopy with image evaluation after ashing.
  • Suitable reinforcers are known to those skilled in the art and are selected, for example, from the group consisting of carbon nanotubes, carbon fibres, boron fibres, glass fibres, glass beads, silica fibres, ceramic fibres, basalt fibres, aluminosilicates, magnesium silicates, calcium carbonates, cellulose, lignin, aramid fibres and polyester fibres.
  • the present invention therefore also provides a sinter powder (SP) in which component (D) is selected from the group consisting of carbon nanotubes, carbon fibres, boron fibres, glass fibres, glass beads, silica fibres, ceramic fibres, basalt fibres, aluminosilicates , magnesium silicates, calcium carbonates, cellulose, lignin, aramid fibres and polyester fibres.
  • SP sinter powder
  • component (D) is selected from the group consisting of carbon nanotubes, carbon fibres, boron fibres, glass fibres, glass beads, silica fibres, ceramic fibres, basalt fibres, aluminosilicates , magnesium silicates, calcium carbonates, cellulose, lignin, aramid fibres and polyester fibres.
  • the at least one reinforcer is preferably selected from the group consisting of aluminosilicates, glass fibres, glass beads, silica fibres and carbon fibres.
  • the at least one reinforcer is more preferably selected from the group consisting of aluminosilicates, glass fibres, glass beads and carbon fibres. These reinforcers may additionally have been amino-functionalized.
  • Suitable silica fibres are, for example, wollastonite.
  • a suitable magnesium silicate is, for example, talc.
  • Suitable aluminosilicates are known as such to the person skilled in the art.
  • Aluminosilicates refer to compounds comprising AI 2 O 3 and SiO 2 .
  • a common factor among the aluminosilicates is that the silicon atoms are tetrahedrally coordinated by oxygen atoms and the aluminum atoms are octahedrally coordinated by oxygen atoms.
  • Aluminosilicates may additionally comprise further elements.
  • Preferred aluminosilicates are sheet silicates.
  • Particularly preferred aluminosilicates are calcined aluminosilicates, especially preferably calcined sheet silicates.
  • the aluminosilicate may additionally have been amino-functionalized.
  • the aluminosilicate may be used in any form.
  • it can be used in the form of the pure aluminosilicate, but it is likewise possible that the aluminosilicate is used in mineral form.
  • the aluminosilicate is used in mineral form.
  • Suitable aluminosilicates are, for example, feldspars, zeolites, sodalite, sillimanite, andalusite and kaolin. Kaolin is a preferred aluminosilicate.
  • Kaolin is one of the day rocks and comprises essentially the mineral kaolinite.
  • the empirical formula of kaolinite is AI 2 [(OH) 4 /Si 2 O 5 ].
  • Kaolinite is a sheet silicate.
  • kaolin typically also comprises further compounds, for example titanium dioxide, sodium oxides and iron oxides.
  • Kaolin preferred in accordance with the invention comprises at least 98% by weight of kaolinite, based on the total weight of the kaolin.
  • the sinter powder comprises component (D), it comprises preferably at least 10% by weight of component (D), based on the sum total of the percentages by weight of components (A), (B), (C) and (D), preferably based on the total weight of the sinter powder (SP).
  • the present invention also provides a method of producing a shaped body, comprising the steps of: i) providing a layer of the sinter powder (SP), ii) exposing the layer of the sinter powder (SP) provided in step i) in order to form the shaped body.
  • SP sinter powder
  • step i a layer of the sinter powder (SP) is provided.
  • the layer of the sinter powder (SP) can be provided by any methods known to those skilled in the art.
  • the layer of the sinter powder (SP) is provided in a construction space on a construction platform.
  • the temperature of the construction space may optionally be controlled.
  • the construction space has, for example, a temperature in the range from 1 to 100 K (kelvin) below the melting temperature (T M(SP) ) of the sinter powder (SP), preferably a temperature in the range from 5 to 50 K below the melting temperature (T M(SP) ) of the sinter powder (SP), and especially preferably a temperature in the range from 10 to 25 K below the melting temperature (T M(SP) ) of the sinter powder (SP).
  • the construction space has, for example, a temperature in the range from 140 to 175°C, preferably in the range from 145 to 170°C, and especially preferably in the range from 150 to 168°C.
  • the layer of the sinter powder (SP) can be provided by any methods known to those skilled in the art.
  • the layer of the sinter powder (SP) is provided by means of a coating bar or a roll in the thickness to be achieved in the construction space.
  • the thickness of the layer of the sinter powder (SP) which is provided in step i) may be as desired. For example, it is in the range from 50 to 300 ⁇ m, preferably in the range from 60 to 200 ⁇ m and especially preferably in the range from 70 to 150 ⁇ m.
  • step ii) the layer of the sinter powder (SP) provided in step i) is exposed.
  • the layer of the sinter powder (SP) melts.
  • the molten sinter powder (SP) coalesces and forms a homogeneous melt.
  • the molten part of the layer of the sinter powder (SP) cools down again and the homogeneous melt solidifies again.
  • Suitable methods of exposure include all methods known to those skilled in the art.
  • the exposure in step ii) is effected with a radiation source.
  • the radiation source is preferably selected from the group consisting of infrared sources and lasers. Especially preferred infrared sources are near infrared sources.
  • the present invention therefore also provides a method in which the exposing in step ii) is effected with a radiation source selected from the group consisting of lasers and infrared sources.
  • Suitable lasers are known to those skilled in the art and are for example fiber lasers, Nd:YAG lasers (neodymium-doped yttrium aluminum garnet laser) or carbon dioxide lasers.
  • the carbon dioxide laser typically has a wavelength of 10.6 ⁇ m.
  • the radiation source used in the exposing in step ii) is a laser
  • the layer of the sinter powder (SP) provided in step i) is typically exposed locally and briefly to the laser beam. This selectively melts just the parts of the sinter powder (SP) that have been exposed to the laser beam.
  • a laser is used in step ii)
  • the method of the invention is also referred to as selective laser sintering. Selective laser sintering is known per se to those skilled in the art.
  • the wavelength at which the radiation source radiates is typically in the range from 780 nm to 1000 ⁇ m, preferably in the range from 780 nm to 50 ⁇ m and especially in the range from 780 nm to 2.5 ⁇ m.
  • step ii) in that case, the entire layer of the sinter powder (SP) is typically exposed.
  • an infrared-absorbing ink IR-absorbing ink
  • the method of producing the shaped body in that case preferably comprises, between step i) and step ii), a step i-1) of applying at least one IR-absorbing ink to at least part of the layer of the sinter powder (SR) provided in step i).
  • the present invention therefore also further provides a method of producing a shaped body, comprising the steps of i) providing a layer of a sinter powder (SP), i-1) applying at least one IR-absorbing ink to at least part of the layer of the sinter powder (SP) provided in step i), ii) exposing the layer of the sinter powder (SP) provided in step i) to which the IR- absorbing ink has been applied.
  • SP sinter powder
  • Suitable IR-absorbing inks are all IR-absorbing inks known to those skilled in the art, especially IR-absorbing inks known to those skilled in the art for high-speed sintering.
  • IR-absorbing inks typically comprise at least one absorber that absorbs IR radiation, preferably NIR radiation (near infrared radiation).
  • NIR radiation near infrared radiation
  • the absorption of the IR radiation, preferably the NIR radiation, by the IR absorber present in the IR-absorbing inks results in selective heating of the part of the layer of the sinter powder (SP) to which the IR-absorbing ink has been applied.
  • the IR-absorbing ink may, as well as the at least one absorber, comprise a carrier liquid.
  • Suitable carrier liquids are known to those skilled in the art and are, for example, oils or solvents.
  • the at least one absorber may be dissolved or dispersed in the carrier liquid.
  • step ii) is effected with a radiation source selected from infrared sources and if step i-1) is conducted
  • the method of the invention is also referred to as high-speed sintering (HSS) or multijet fusion (MJF) method. These methods are known per se to those skilled in the art.
  • the layer of the sinter powder (SP) is typically lowered by the layer thickness of the layer of the sinter powder (SP) provided in step i) and a further layer of the sinter powder (SP) is applied. This is subsequently exposed again in step ii). This firstly bonds the upper layer of the sinter powder (SP) to the lower layer of the sinter powder (SP); in addition, the particles of the sinter powder (SP) within the upper layer are bonded to one another by fusion.
  • steps i) and ii) and optionally i-1) can thus be repeated.
  • the present invention also further provides for the use of the sinter powder (SP) in a sintering method, preferably in a selective laser sintering method (SLS), a high-speed sintering method (HSS) or a multi-jet fusion method (MJF).
  • SP sinter powder
  • the present invention therefore also further provides a shaped body obtained by the methods of the invention.
  • the process of the invention affords a shaped body.
  • the shaped body can be removed from the powder bed directly after the solidification of the sinter powder (SP) molten on exposure in step ii). It is likewise possible first to cool the shaped body and only then to remove it from the powder bed. Any adhering particles of the sinter powder (SP) that have not been melted can be mechanically removed from the surface by known methods. Methods for surface treatment of the shaped body include, for example, vibratory grinding or barrel polishing, and also sandblasting, glass bead blasting or microbead blasting.
  • the shaped body additionally typically comprises the IR-absorbing ink.
  • components (A) and (B), and optionally (C) and (D), do not enter into any chemical reaction on exposure in step ii); instead, the sinter powder (SP) merely melts.

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Abstract

The present invention relates to a sinter powder (SP) comprising at least one polylactide (A), at least one polycaprolactone (B), optionally at least one additive (C) and optionally at least one reinforcer (D). The present invention further relates to a method of producing a shaped body using the inventive sinter powder (SP), to a shaped body obtained by this method and to the use of the inventive sinter powder (SP) in a sintering method. In addition, the present invention relates to a method of producing the sinter powder (SP) and to the use of at least one polycaprolactone (B) in a sinter powder (SP) comprising at least one polylactide (A) for improving the mechanical properties of shaped bodies made from said sinter powder (SP).

Description

Sinter powder (SP) comprising at least one polylactide and at least one polycaprolactone
Description
The present invention relates to a sinter powder (SP) comprising at least one polylactide (A), at least one polycaprolactone (B), optionally at least one additive (C) and optionally at least one reinforcer (D). The present invention further relates to a method of producing a shaped body using the inventive sinter powder (SP), to a shaped body obtained by this method and to the use of the inventive sinter powder (SP) in a sintering method. In addition, the present invention relates to a method of producing the sinter powder (SP) and to the use of at least one polycaprolactone (B) in a sinter powder (SP) comprising at least one polylactide (A) for improving the mechanical properties of shaped bodies made from said sinter powder (SP).
The rapid provision of prototypes is a problem often addressed in very recent times. One process, which is particularly suitable for this so-called „rapid prototyping", is selective laser sintering (SLS). This involves selectively exposing of a polymer powder in a chamber with a laser beam. The powder melts; the molten particles coalesce and resolidify. Repeated application of polymer powder and subsequent exposure to a laser allows modelling of three-dimensional shaped bodies.
The process of selective laser sintering for producing shaped bodies from pulverulent polymers is described in detail in patent specifications US 6,136,948 and WO 96/06881.
Selective laser sintering is frequently too time-consuming for the production of a relatively large number of shaped bodies, and so it is possible to produce relatively large volumes of shaped bodies using high-speed sintering (HSS) or “multi-jet fusion technology” (MJF) from HP. In high-speed sintering, by spray application of an infraredabsorbing ink onto the component cross section to be sintered, followed by exposure with an infrared source, a higher processing speed is achieved compared to selective laser sintering.
Polylactide (PLA) is a well-known thermoplastic polymer used primarily in bioplastic applications. It is obtained by polymerizing a mixture of L-lactic acid and D-lactic acid, yielding either an amorphous or a semi-crystalline polymer, based on the ratio of D- lactic acid to L-lactic acid. Thus, when applying polylactide in a laser sintering process, it is difficult to choose the correct material grade with ideal melting and crystallization characteristics. Additionally, shaped bodies produced with pure PLA of a high L-lactic content show generally poor mechanical properties, are brittle and have low toughness. In the previous state of the art, the laser sintering characteristics of PLA powders along with incorporating additives or biomass blend components to improve the processability of PLA powders are described. However, only moderate improvements to the part flexibility is noted with significant loss to mechanical strength.
In the article “Processing and Characterization of a Polylactic Acid/Nanoclay Composite for Laser Sintering” by J. Bai et al. (Polymer Composites, 2015), the feasibility of processing polylactic acid (PLA) and a PLA/nanoclay composite by laser sintering are investigated. Under the same powder bed temperature, PLA/nanoclay parts exhibit an improvement in flexural modulus compared with neat PLA.
In the article “Optimize Print Speed and Laser Power of the 3D Printing Technology Selective Laser Sintering (SLS) for Mixture of Powder Materials Green Bean and Polylactic Acid (GBP/PLA)” by B. B. Dinh et al. (IOP Conference Series: Materials Science and Engineering, 2020, 782), a sintering (SLS) 3D printing mode for a mixture of Green Bean Powder and Polylactic acid powder (GBP/PLA) is optimized.
In the article “LASER SINTERING OF PINE/POLYLATIC ACID COMPOSITES” by H. Zhang et al. (Solid Freeform Fabrication, 2019), a powder feedstock comprising polylactic acid (PLA) powder and pine powder is proposed for laser sintering technology.
In the article “Effects of Ingredient Proportions on the Performance of a-Cellulose/PLA Mixtures Used for Laser Sintering” by H. Zhang et al. (Bioresources, 2020, 15, 5886), a powder feedstock comprising polylactic acid powder and of a-cellulose powder is evaluated for laser sintering.
WO 2020/099236 A1 describes a polymer powder for use as build material for production of a three-dimensional object by layer-by-layer melting and solidification of the build material at the sites corresponding to the cross section of the three- dimensional object in the respective layer by the action of radiation, preferably by the action of NIR radiation, wherein the polymer powder comprises a dry blend of polymer- based particles and particles of an NIR absorber, wherein the NIR absorber comprises carbon black or is carbon black. The polymer can be a polylactide.
WO 2018/173755 A1 describes a resin powder for producing a three-dimensional object, wherein the resin powder has a number-average equivalent circle diameter of 10 micrometers or greater but 150 micrometers or less, and wherein a median in an equivalent circle diameter-based particle size distribution of the resin powder is higher than the average equivalent circle diameter. The resin can be polylactic acid. US 2018/0178445 A1 discloses a method of manufacturing a three-dimensional product having uniform mechanical properties using an SLS 3D printer including the steps of: preparing a mixed powder material by mixing resin powder and glass bubbles, wherein the specific gravity of the glass bubbles is from about 0.8 to about 1.2 times that of the resin powder. The resin powder may be polylactic acid.
WO 2018/046582 A1 describes a thermoplastic polymer powder and the use thereof as material for selective laser sintering (SLS). The polymer powder contains a partially crystalline polymer, an amorphous polymer and a compatibilizing agent, and optionally additional additives and/or auxiliary substances, wherein the partially crystalline polymer, the amorphous polymer and the compatibilizing agent are in the form of a polymer blend. The thermoplastic polymer powder can comprise 10 to 89.9% by weight polylactide.
WO 2020/058313 A1 discloses a method for producing a three-dimensional component by selective laser sintering (SLS), wherein a processing temperature Tx is set in a build chamber, and a powder layer, consisting of a thermoplastic polymer powder, is provided in said build chamber. The polymer powder contains a blend of a semicrystalline polymer, an amorphous polymer, and a polymer compatibilizer. The polymer powder can comprise 20 to 79.9% by weight polylactide.
It is thus an object of the present invention to provide an improved sinter powder (SP) comprising polylactide which, in a process for the production of shaped bodies by laser sintering, does not have, or only has to a small extent, the aforementioned disadvantages of the sinter powders and processes described in the prior art. The sinter powder and the process should be as simple and inexpensive as possible to produce and carry out.
This object is achieved by a sinter powder (SP) comprising the following components:
(A) at least one polylactide,
(B) at least one polycaprolactone,
(C) optionally at least one additive and
(D) optionally at least one reinforcer.
It has been found that, surprisingly, the sinter powder (SP) of the invention can be used efficiently in selective laser sintering methods, high-speed sintering methods and multijet fusion methods.
The shaped bodies obtained by these methods show improved mechanical properties compared to shaped bodies comprising pure polylactide, for example, an improved toughness without scarifying mechanical strength. The sinter powder (SP) of the invention is elucidated in detail hereinafter.
Sinter powder (SP)
According to the invention, the sinter powder (SP) comprises at least one polylactide as component (A), at least one polycaprolactone as component (B), optionally at least one additive as component (C), and optionally at least one reinforcer as component (D).
In the context of the present invention, the terms “component (A)” and “at least one polylactide” are used synonymously and therefore have the same meaning. The same applies to the terms “component (B)” and “at least one polycaprolactone”. These terms are likewise used synonymously in the context of the present invention and therefore have the same meaning.
Accordingly, the terms “component (C)” and “at least one additive”, and “component (D)” and “at least one reinforcer” are also each used synonymously in the context of the present invention and therefore have the same meaning.
In a preferred embodiment, the sinter powder (SP) comprises 10% to 92.5% by weight of component (A), 7.5% to 30% by weight of component (B), 0% to 20% by weight of component (C), and 0% to 40% by weight of component (D), based in each case on the total weight of the sinter powder (SP).
The percentages by weight of components (A), (B), and optionally of components (C) and (D), typically add up to 100% by weight.
The present invention thus also provides a sinter powder (SP), wherein the sinter powder (SP) comprises
10% to 92.5% by weight of component (A),
7.5% to 30% by weight of component (B),
0% to 20% by weight of component (C) and
0% to 40% by weight of component (D), based in each case on the total weight of the sinter powder (SP).
The sinter powder (SP) comprises particles. These particles have, for example, a median particle size (D50) in the range from 40 to 80 μm, preferably in the range from 45 to 75 μm, and more preferably in the range from 45 to 70 μm.
The sinter powder (SP) of the invention has, for example, a D10 in the range from 10 to 60 μm, a D50 in the range from 40 to 80 μm and a D90 in the range from 50 to 150 μm.
Preferably, the sinter powder (SP) of the invention has a D10 in the range from 20 to 50 μm, a D50 in the range from 45 to 75 μm and a D90 in the range from 80 to 125 μm.
The present invention therefore also provides a sinter powder (SP) having a D10 in the range from 10 to 60 μm, a D50 in the range from 40 to 80 μm and a D90 in the range from 50 to 150 μm.
The present invention therefore also provides a sinter powder (SP) having a median particle size (D50) in the range from 40 to 80 μm.
In the context of the present invention, the "D10" is understood to mean the particle size at which 10% by volume of the particles based on the total volume of the particles are smaller than or equal to D10 and 90% by volume of the particles based on the total volume of the particles are larger than D10. By analogy, the "D50" is understood to mean the particle size at which 50% by volume of the particles based on the total volume of the particles are smaller than or equal to D50 and 50% by volume of the particles based on the total volume of the particles are larger than D50. Correspondingly, the "D90" is understood to mean the particle size at which 90% by volume of the particles based on the total volume of the particles are smaller than or equal to D90 and 10% by volume of the particles based on the total volume of the particles are larger than D90.
To determine the particle sizes, the sinter powder (SP) is suspended in a dry state using compressed air or in a solvent, for example water or ethanol, and this suspension is analyzed. The D10, D50 and D90 values are determined by laser diffraction using a Malvern Mastersizer 3000. Evaluation is by means of Fraunhofer diffraction.
The sinter powder (SP) typically has a melting temperature (TM(SP)) in the range from 150 to 180°C. Preferably, the melting temperature (TM(SP)) of the sinter powder (SP) is in the range from 170 to 180 °C. The melting temperature (TM(SP)) is determined in the context of the present invention by means of differential scanning calorimetry (DSC). Typically, a heating run (H1) and a cooling run (C) are measured, each at a heating rate/cooling rate of 20 K/min. This affords a DSC diagram. The melting temperature (TM(SP)) is then understood to mean the temperature at which the melting peak of the heating run (H1) of the DSC diagram has a maximum.
The present invention therefore also provides a sinter powder (SP), wherein the melting temperature (TM(SP)) of the sinter powder (SP) is in the range from 150 to 180°C
The sinter powder (SP) typically also has a crystallization temperature (Tc) in the range from 70 to 130°C. Preferably, the crystallization temperature (Tc) of the sinter powder (SP) is in the range from 80 to 120°C and especially preferably in the range from 90 to 110°C.
The crystallization temperature (Tc) is determined in the context of the present invention by means of differential scanning calorimetry (DSC). As described above, this customarily involves measuring a heating run (H) and a cooling run (C). This gives a DSC diagram. The crystallization temperature (Tc) is then the temperature at the minimum of the crystallization peak of the DSC curve.
The sinter powder (SP) typically also has a glass transition temperature (TG). The glass transition temperature (TG) of the sinter powder (SP) is, for example, in the range from 20 to 80°C, preferably in the range from 30 to 70°C and especially preferably in the range from 40 to 60°C.
The glass transition temperature (TG) of the sinter powder (SP) is determined by means of differential scanning calorimetry. For determination, in accordance with the invention, first a first heating run (H1), then a cooling run (C) and subsequently a second heating run (H2) is measured on a sample of the sinter powder (SP). The heating rate in the first heating run (H1) and in the second heating run (H2) is 20 K/min; the cooling rate in the cooling run (C) is likewise 20 K/min. In the region of the glass transition of the sinter powder (SP), a step is obtained in the second heating run (H2) in the DSC diagram. The glass transition temperature (TG) of the sinter powder (SP) corresponds to the temperature at half the step height in the DSC diagram. This process for determination of the glass transition temperature is known to those skilled in the art.
The sinter powder (SP) can be produced by any methods known to those skilled in the art. For example, the sinter powder (SP) is produced by grinding, by precipitation, by melt emulsification, by spray extrusion or by microgranulation. The production of the sinter powder (SP) by grinding, by precipitation, by melt emulsification, by spray extrusion or by microgranulation is also referred to as micronization in the context of the present invention.
If the sinter powder (SP) is produced by precipitation, components (A) and (B), and optionally (C) and (D), are usually mixed with a solvent, and component (A) and component (B) are dissolved in the solvent, optionally with heating, to obtain a solution. The precipitation of the sinter powder (SP) is then carried out, for example, by cooling the solution, distilling off the solvent from the solution or adding a precipitating agent to the solution.
Grinding can be carried out by any method known to a person skilled in the art, for example, components (A) and (B), and optionally (C) and (D), are introduced in a mill and ground therein.
Suitable mills include all mills known to those skilled in the art, for example classifier mills, opposed jet mills, hammer mills, ball mills, vibratory mills or rotor mills such as pinned disk mills and whirlwind mills.
The grinding in the mill can likewise be effected by any methods known to those skilled in the art. For example, the grinding can take place under inert gas and/or while cooling with liquid nitrogen. Cooling with liquid nitrogen is preferred. The temperature in the grinding is as desired; the grinding is preferably performed at liquid nitrogen temperatures, for example at a temperature in the range from -210 to -195°C. The temperature of the components on grinding in that case is, for example, in the range from -40 to -10°C.
Preferably, the components are first mixed with one another and then ground.
Preferably, at least components (A) and (B) are in the form of granules before micronization. In addition to components (A) and (B), components (C) and (D) may also be present in the form of granules. The granulate can be spherical, cylindrical or elliptical, for example. In the context of the present invention, in a preferred embodiment, a granulate is used which comprises components (A) and (B), and optionally (C) and (D), premixed.
The method of producing the sinter powder (SP) then preferably comprises the steps of a) mixing components (A) and (B), and optionally (C) and/or (D):
(A) at least one polylactide,
(B) at least one polycaprolactone,
(C) optionally at least one additive, and/or (D) optionally at least one reinforcer, in an extruder to obtain an extrudate (E) comprising components (A) and (B), and optionally (C) and/or (D), b) pelletizing the extrudate (E) obtained in step a) to obtain a granulate (G) comprising components (A) and (B), and optionally (C) and/or (D), c) micronizing the granulate (G) obtained in step b) to obtain the sinter powder (SP), preferably by grinding.
It is therefore also an object of the present invention to provide a method of producing the sinter powder (SP) comprising the steps of a) mixing components (A) and (B), and optionally (C) and/or (D):
(A) at least one polylactide,
(B) at least one polycaprolactone,
(C) optionally at least one additive, and/or
(D) optionally at least one reinforcer, in an extruder to obtain an extrudate (E) comprising components (A) and (B), and optionally (C) and/or (D), b) pelletizing the extrudate (E) obtained in step a) to obtain a granulate (G) comprising components (A) and (B), and optionally (C) and/or (D), c) micronizing the granulate (G) obtained in step b) to obtain the sinter powder (SP).
In a further preferred embodiment, the method of producing the sinter powder (SP) comprises the following steps: a) mixing components (A) and (B), and optionally (C) and/or (D):
(A) at least one polylactide,
(B) at least one polycaprolactone,
(C) optionally at least one additive, and/or
(D) optionally at least one reinforcer, in an extruder to obtain an extrudate (E) comprising components (A) and (B), and optionally (C) and/or (D), b) pelletizing the extrudate (E) obtained in step a) to obtain a granulate (G) comprising components (A) and (B), and optionally (C) and/or (D), c1) micronizing the granulate (G) obtained in step b) to obtain a polylactide powder (PP), c2) mixing the polylactide powder (PP) obtained in step c1) with a free-flow aid to obtain the sinter powder (SP).
If the sinter powder (SP) comprises component (D), a granulate is preferably used which comprises only components (A) and (B), and, optionally, component (C) premixed. The at least one reinforcing agent (D) is then preferably added after the micronization step.
The method of producing the sinter powder (SP) then preferably comprises the steps of a) mixing components (A) and (B), and optionally (C):
(A) at least one polylactide,
(B) at least one polycaprolactone, and
(C) optionally at least one additive, in an extruder to obtain an extrudate (E1) comprising components (A) and (B), and optionally (C), b) pelletizing the extrudate (E1) obtained in step a) to obtain a granulate (G1) comprising components (A) and (B), and optionally (C), c) micronizing the granulate (G1) obtained in step b) to obtain a sinter powder (SP1), preferably by grinding, d) mixing the sinter powder (SP1) and component (D):
(D) at least one reinforcer, to obtain the sinter powder (SP).
If a free-flow aid is added during the process of producing the sinter powder (SP), the process then preferably comprises the following steps: a) mixing components (A) and (B), and optionally (C): (A) at least one polylactide,
(B) at least one polycaprolactone, and
(C) optionally at least one additive, in an extruder to obtain an extrudate (E1) comprising components (A) and (B), and optionally (C), b) pelletizing the extrudate (E1) obtained in step a) to obtain a granulate (G1) comprising components (A) and (B), and optionally (C), c1) micronizing the granulate (G1) obtained in step b) to obtain a polylactide powder (PP1), preferably by grinding, c2) mixing the polylactide powder (PP1) obtained in step c1) with a free-flow aid to obtain a sinter powder (SP2), d) mixing the sinter powder (SP2) and component (D):
(D) at least one reinforcer, to obtain the sinter powder (SP).
Suitable free-flow aids are, for example, silicas, amorphous silicon oxide or aluminium oxides. A suitable aluminium oxide is, for example, Aeroxide® Alu C from Evonik. A suitable amorphous silica is, for example, HDK N20 from Wacker.
Thus, it is also an object of the present invention to provide a sinter powder (SP) in which the free-flow aid in step c2) is selected from silicas, amorphous silicon oxide and/or aluminium oxides.
In the case that the sinter powder (SP) comprises a free-flow aid, this is preferably added in process step c2). In one preferred embodiment, the sinter powder (SP) comprises 0.02 to 1 % by weight, preferably 0.05 to 0.8% by weight and particularly preferably 0.1 to 0.6% by weight of the free-flow aid, in each case based on the total weight of the polylactide powder (PP) or (PP1), respectively, and the free-flow aid.
For the grinding in step c) and in step c1), the previously described explanations and preferences with regard to the grinding apply accordingly.
A further object of the present invention is therefore also the sinter powder (SP), obtained by the process according to the invention. Component (A)
According to the invention, component (A) is at least one polylactide. In the context of the present invention, the terms “component (A)” and “at least one polylactide” are used synonymously and therefore have the same meaning. In the context of the present invention, “at least one polylactide” means either exactly one polylactide or mixtures of two or more polylactides. Preferably, component (A) is exactly one polylactide.
The at least one polylactide (A) is preferably obtained by polymerizing a mixture (M) of L-lactic acid and D-lactic acid, wherein the mixture (M) comprises at most 10% by weight, preferably at most 5% by weight, and most preferably at most 2% by weight, of D-lactic acid, based on the total weight of the mixture (M).
The present invention, therefore, also provides a sinter powder (SP), wherein the at least one polylactide (A) is obtained by polymerizing a mixture (M) of L-lactic acid and D-lactic acid, wherein the mixture (M) comprises at most 10% by weight, preferably at most 5% by weight, and most preferably at most 2% by weight, of D-lactic acid, based on the total weight of the mixture (M).
Preferably, the at least one polylactide (A) has a melting temperature (TM(A)) in the range from 150 to 180°C, more preferably in the range from 170 to 180°C, determined as described above.
The present invention, therefore, also provides a sinter powder (SP), wherein the melting temperature (TM(A)) of the at least one polylactide (A) is in the range from 150 to 180°C.
The at least one polylactide (A) typically also has a crystallization temperature (TC(A)) in the range from 70 to 130°C. Preferably, the crystallization temperature (TC<A)) of the at least one polylactide (A) is in the range from 80 to 120°C and especially preferably in the range from 90 to 110°C.
The crystallization temperature (TC(A)) is determined in the context of the present invention by means of differential scanning calorimetry (DSC). As described above, this customarily involves measuring a heating run (H) and a cooling run (C). This gives a DSC diagram. The crystallization temperature (Tc) is then the temperature at the minimum of the crystallization peak of the DSC curve. The at least one polylactide (A) preferably has a relative viscosity in the range from 2.0 to 4.0, more preferably in the range from 2.5 to 3.5, measured at 1.0 g/dL in chloroform at 30°C according to ASTM D5225.
In addition, the at least one polylactide (A) preferably has a specific gravity in the range from 1.0 to 1.5 g/cm3, more preferably in the range from 1.1 to 1.4 g/cm3, determined according to ASTM D792.
Further, the at least one polylactide (A) preferably has a melt index in the range from 20.0 to 30.0 g/10 min at 2,16 kg and 210 °C, more preferably in the range from 22.0 to 28.0 g/10 min at 2,16 kg and 210 °C, determined according to ASTM D1238.
The present invention, therefore, also provides a sinter powder (SP), wherein the at least one polylactide (A) has i) a relative viscosity in the range from 2.0 to 4.0, and/or ii) a specific gravity in the range from 1.0 to 1.5 g/cm3, and/or iii) a melt index in the range from 20.0 to 30.0 g/10 min.
An example of a suitable polylactide is the polylactide Ingeo™ Biopolymer 6100D obtainable from NatureWorks.
Component (B)
According to the invention, component (B) is at least one polycaprolactone. In the context of the present invention, the terms “component (B)” and “at least one polycaprolactone” are used synonymously and therefore have the same meaning. In the context of the present invention, “at least one polycaprolactone” means either exactly one polycaprolactone or mixtures of two or more polycaprolactones. Preferably, component (B) is exactly one polycaprolactone.
Preferably, the at least one polycaprolactone (B) has a melting temperature (TM(B)) in the range from 55 to 65°C.
Suitable polycaprolactones (B) have a mean molecular weight (M(B)) in the range from 30 000 to 70 000 g/mol, and preferably in the range from 40 000 to 60 000 g/mol.
The at least one polycaprolactone (B) preferably has a melt flow index in the range from 5.5 to 8.5 g/10 min at 2.16 kg and 160°C. An example of a suitable polycaprolactone is the polycaprolactone Capa™ 6500 obtainable from Ingevity.
The use of the at least one polycaprolactone (B) in a sinter powder (SP) comprising at least one polylactide (A) improves the mechanical properties of shaped bodies made from said sinter powder (SP).
The present invention therefore also provides the use of at least one polycaprolactone
(B) in a sinter powder (SP) comprising at least one polylactide (A) for improving the mechanical properties of shaped bodies made from said sinter powder (SP).
Component (C)
Component (C) is at least one additive.
In the context of the present invention, “at least one additive” means either exactly one additive or a mixture of two or more additives.
Additives as such are known to those skilled in the art. For example, the at least one additive is selected from the group consisting of antinucleating agents, stabilizers, conductive additives, end group functionalizers, dyes, antioxidants (preferably sterically hindered phenols, and phosphites as secondary stabilizers), nucleating agents and colour pigments.
The present invention therefore also provides a sinter powder (SP) in which component
(C) is selected from the group consisting of antinucleating agents, stabilizers, conductive additives, end group functionalizers, dyes, antioxidants, nucleating agents and colour pigments.
An example of a suitable antinucleating agent is lithium chloride. Suitable stabilizers are, for example, phenols, phosphites and copper stabilizers. Suitable conductive additives are carbon fibres, metals, stainless steel fibres, carbon nanotubes and carbon black. Suitable end group functionalizers are, for example, terephthalic acid, adipic acid and propionic acid. Suitable dyes and colour pigments are, for example, carbon black and iron chromium oxides. Suitable nucleating agents are talcum or D-Lactide.
Suitable antioxidants are, for example, Irganox® 245, Irganox® 1076, Irganox® B900, Irganox® 1098 and Irgafos® 168 from BASF SE or Weston® TNPP phosphite from Addivant.
If the sinter powder comprises component (C), it comprises at least 0.1% by weight of component (C), preferably at least 0.2% by weight of component (C), based on the sum total of the proportions by weight of components (A), (B), (C) and (D), preferably based on the total weight of the sinter powder (SP).
Component (D)
According to the invention, any component (D) present is at least one reinforcer.
In the context of the present invention, "at least one reinforcer" means either exactly one reinforcer or a mixture of two or more reinforcers.
In the context of the present invention, a reinforcer is understood to mean a material that improves the mechanical properties of shaped bodies produced by the process of the invention compared to shaped bodies that do not comprise the reinforcer.
Reinforcers as such are known to those skilled in the art. Component (D) may, for example, be in spherical form, in platelet form or in fibrous form.
Preferably, the at least one reinforcer is in platelet form or in fibrous form.
A "fibrous reinforcer" is understood to mean a reinforcer in which the ratio of length of the fibrous reinforcer to the diameter of the fibrous reinforcer is in the range from 2:1 to 40:1, preferably in the range from 3:1 to 30:1 and especially preferably in the range from 5:1 to 20:1 , where the length of the fibrous reinforcer and the diameter of the fibrous reinforcer are determined by microscopy by means of image evaluation on samples after ashing, with evaluation of at least 70 000 parts of the fibrous reinforcer after ashing.
The length of the fibrous reinforcer in that case is typically in the range from 5 to 1000 μm, preferably in the range from 10 to 600 μm and especially preferably in the range from 20 to 500 μm, determined by means of microscopy with image evaluation after ashing.
The diameter in that case is, for example, in the range from 1 to 30 μm, preferably in the range from 2 to 20 μm and especially preferably in the range from 5 to 15 μm, determined by means of microscopy with image evaluation after ashing. in a further preferred embodiment, the at least one reinforcer is in platelet form. In the context of the present invention, "in platelet form" is understood to mean that the particles of the at least one reinforcer have a ratio of diameter to thickness in the range from 4:1 to 10:1 , determined by means of microscopy with image evaluation after ashing. Suitable reinforcers are known to those skilled in the art and are selected, for example, from the group consisting of carbon nanotubes, carbon fibres, boron fibres, glass fibres, glass beads, silica fibres, ceramic fibres, basalt fibres, aluminosilicates, magnesium silicates, calcium carbonates, cellulose, lignin, aramid fibres and polyester fibres.
The present invention therefore also provides a sinter powder (SP) in which component (D) is selected from the group consisting of carbon nanotubes, carbon fibres, boron fibres, glass fibres, glass beads, silica fibres, ceramic fibres, basalt fibres, aluminosilicates , magnesium silicates, calcium carbonates, cellulose, lignin, aramid fibres and polyester fibres.
The at least one reinforcer is preferably selected from the group consisting of aluminosilicates, glass fibres, glass beads, silica fibres and carbon fibres.
The at least one reinforcer is more preferably selected from the group consisting of aluminosilicates, glass fibres, glass beads and carbon fibres. These reinforcers may additionally have been amino-functionalized.
Suitable silica fibres are, for example, wollastonite. A suitable magnesium silicate is, for example, talc.
Suitable aluminosilicates are known as such to the person skilled in the art. Aluminosilicates refer to compounds comprising AI2O3 and SiO2. In structural terms, a common factor among the aluminosilicates is that the silicon atoms are tetrahedrally coordinated by oxygen atoms and the aluminum atoms are octahedrally coordinated by oxygen atoms. Aluminosilicates may additionally comprise further elements.
Preferred aluminosilicates are sheet silicates. Particularly preferred aluminosilicates are calcined aluminosilicates, especially preferably calcined sheet silicates. The aluminosilicate may additionally have been amino-functionalized.
If the at least one reinforcer is an aluminosilicate, the aluminosilicate may be used in any form. For example, it can be used in the form of the pure aluminosilicate, but it is likewise possible that the aluminosilicate is used in mineral form. Preferably, the aluminosilicate is used in mineral form. Suitable aluminosilicates are, for example, feldspars, zeolites, sodalite, sillimanite, andalusite and kaolin. Kaolin is a preferred aluminosilicate.
Kaolin is one of the day rocks and comprises essentially the mineral kaolinite. The empirical formula of kaolinite is AI2[(OH)4/Si2O5]. Kaolinite is a sheet silicate. As well as kaolinite, kaolin typically also comprises further compounds, for example titanium dioxide, sodium oxides and iron oxides. Kaolin preferred in accordance with the invention comprises at least 98% by weight of kaolinite, based on the total weight of the kaolin.
If the sinter powder comprises component (D), it comprises preferably at least 10% by weight of component (D), based on the sum total of the percentages by weight of components (A), (B), (C) and (D), preferably based on the total weight of the sinter powder (SP).
Shaped bodies
The present invention also provides a method of producing a shaped body, comprising the steps of: i) providing a layer of the sinter powder (SP), ii) exposing the layer of the sinter powder (SP) provided in step i) in order to form the shaped body.
Step i)
In step i), a layer of the sinter powder (SP) is provided.
The layer of the sinter powder (SP) can be provided by any methods known to those skilled in the art. Typically, the layer of the sinter powder (SP) is provided in a construction space on a construction platform. The temperature of the construction space may optionally be controlled.
The construction space has, for example, a temperature in the range from 1 to 100 K (kelvin) below the melting temperature (TM(SP)) of the sinter powder (SP), preferably a temperature in the range from 5 to 50 K below the melting temperature (TM(SP)) of the sinter powder (SP), and especially preferably a temperature in the range from 10 to 25 K below the melting temperature (TM(SP)) of the sinter powder (SP).
The construction space has, for example, a temperature in the range from 140 to 175°C, preferably in the range from 145 to 170°C, and especially preferably in the range from 150 to 168°C.
The layer of the sinter powder (SP) can be provided by any methods known to those skilled in the art. For example, the layer of the sinter powder (SP) is provided by means of a coating bar or a roll in the thickness to be achieved in the construction space. The thickness of the layer of the sinter powder (SP) which is provided in step i) may be as desired. For example, it is in the range from 50 to 300 μm, preferably in the range from 60 to 200 μm and especially preferably in the range from 70 to 150 μm.
Step ii)
In step ii), the layer of the sinter powder (SP) provided in step i) is exposed.
On exposure, at least some of the layer of the sinter powder (SP) melts. The molten sinter powder (SP) coalesces and forms a homogeneous melt. After the exposure, the molten part of the layer of the sinter powder (SP) cools down again and the homogeneous melt solidifies again.
Suitable methods of exposure include all methods known to those skilled in the art. Preferably, the exposure in step ii) is effected with a radiation source. The radiation source is preferably selected from the group consisting of infrared sources and lasers. Especially preferred infrared sources are near infrared sources.
The present invention therefore also provides a method in which the exposing in step ii) is effected with a radiation source selected from the group consisting of lasers and infrared sources.
Suitable lasers are known to those skilled in the art and are for example fiber lasers, Nd:YAG lasers (neodymium-doped yttrium aluminum garnet laser) or carbon dioxide lasers. The carbon dioxide laser typically has a wavelength of 10.6 μm.
If the radiation source used in the exposing in step ii) is a laser, the layer of the sinter powder (SP) provided in step i) is typically exposed locally and briefly to the laser beam. This selectively melts just the parts of the sinter powder (SP) that have been exposed to the laser beam. If a laser is used in step ii), the method of the invention is also referred to as selective laser sintering. Selective laser sintering is known per se to those skilled in the art.
If the radiation source used in the exposing in step ii) is an infrared source, especially a near infrared source, the wavelength at which the radiation source radiates is typically in the range from 780 nm to 1000 μm, preferably in the range from 780 nm to 50 μm and especially in the range from 780 nm to 2.5 μm.
In the exposing in step ii), in that case, the entire layer of the sinter powder (SP) is typically exposed. In order that only the desired regions of the sinter powder (SP) melt in the exposing, an infrared-absorbing ink (IR-absorbing ink) is typically applied to the regions that are to melt. The method of producing the shaped body in that case preferably comprises, between step i) and step ii), a step i-1) of applying at least one IR-absorbing ink to at least part of the layer of the sinter powder (SR) provided in step i).
The present invention therefore also further provides a method of producing a shaped body, comprising the steps of i) providing a layer of a sinter powder (SP), i-1) applying at least one IR-absorbing ink to at least part of the layer of the sinter powder (SP) provided in step i), ii) exposing the layer of the sinter powder (SP) provided in step i) to which the IR- absorbing ink has been applied.
Suitable IR-absorbing inks are all IR-absorbing inks known to those skilled in the art, especially IR-absorbing inks known to those skilled in the art for high-speed sintering.
IR-absorbing inks typically comprise at least one absorber that absorbs IR radiation, preferably NIR radiation (near infrared radiation). In the exposing of the layer of the sinter powder (SP) in step ii), the absorption of the IR radiation, preferably the NIR radiation, by the IR absorber present in the IR-absorbing inks results in selective heating of the part of the layer of the sinter powder (SP) to which the IR-absorbing ink has been applied.
The IR-absorbing ink may, as well as the at least one absorber, comprise a carrier liquid. Suitable carrier liquids are known to those skilled in the art and are, for example, oils or solvents.
The at least one absorber may be dissolved or dispersed in the carrier liquid.
If the exposing in step ii) is effected with a radiation source selected from infrared sources and if step i-1) is conducted, the method of the invention is also referred to as high-speed sintering (HSS) or multijet fusion (MJF) method. These methods are known per se to those skilled in the art.
After step ii), the layer of the sinter powder (SP) is typically lowered by the layer thickness of the layer of the sinter powder (SP) provided in step i) and a further layer of the sinter powder (SP) is applied. This is subsequently exposed again in step ii). This firstly bonds the upper layer of the sinter powder (SP) to the lower layer of the sinter powder (SP); in addition, the particles of the sinter powder (SP) within the upper layer are bonded to one another by fusion.
In the process of the invention, steps i) and ii) and optionally i-1) can thus be repeated.
By repeating the lowering of the powder bed, the applying of the sinter powder (SP) and the exposure and hence the melting of the sinter powder (SP), three-dimensional shaped bodies are produced. It is possible to produce shaped bodies that also have cavities, for example. No additional support material is necessary since the unmolten sinter powder (SP) itself acts as a support material.
The present invention also further provides for the use of the sinter powder (SP) in a sintering method, preferably in a selective laser sintering method (SLS), a high-speed sintering method (HSS) or a multi-jet fusion method (MJF).
The present invention therefore also further provides a shaped body obtained by the methods of the invention.
The process of the invention affords a shaped body. The shaped body can be removed from the powder bed directly after the solidification of the sinter powder (SP) molten on exposure in step ii). It is likewise possible first to cool the shaped body and only then to remove it from the powder bed. Any adhering particles of the sinter powder (SP) that have not been melted can be mechanically removed from the surface by known methods. Methods for surface treatment of the shaped body include, for example, vibratory grinding or barrel polishing, and also sandblasting, glass bead blasting or microbead blasting.
It is also possible to subject the shaped bodies obtained to further processing or, for example, to treat the surface.
If step i-1) has been conducted, the shaped body additionally typically comprises the IR-absorbing ink.
It will be clear to those skilled in the art that, as a result of the exposure of the sinter powder (SP), components (A) and (B), and optionally (C) and/or (D), can enter into chemical reactions and be altered as a result. Such reactions are known to those skilled in the art.
Preferably, components (A) and (B), and optionally (C) and (D), do not enter into any chemical reaction on exposure in step ii); instead, the sinter powder (SP) merely melts.

Claims

Claims
1. A sinter powder (SP) comprising the following components:
(A) at least one polylactide,
(B) at least one polycaprolactone,
(C) optionally at least one additive and
(D) optionally at least one reinforcer.
2. The sinter powder (SP) according to claim 1, wherein the at least one polylactide (A) is obtained by polymerizing a mixture (M) of L-lactic acid and D- lactic acid, wherein the mixture (M) comprises at most 10% by weight, preferably at most 5% by weight, and most preferably at most 2% by weight, of D-lactic acid, based on the total weight of the mixture (M).
3. The sinter powder (SP) according to claim 1 or 2, wherein the melting temperature (TM(A>) of the at least one polylactide (A) is in the range from 150 to 180°C.
4. The sinter powder (SP) according to any of claims 1 to 3, wherein the at least one polylactide (A) has i) a relative viscosity in the range from 2.0 to 4.0, and/or ii) a specific gravity in the range from 1.0 to 1.5 g/cm3, and/or iii) a melt index in the range from 20.0 to 30.0 g/10 min.
5. The sinter powder (SP) according to any of claims 1 to 4, wherein the melting temperature (TM(SP)) of the sinter powder (SP) is in the range from 150 to 180°C.
6. The sinter powder (SP) according to any of claims 1 to 5, wherein the sinter powder (SP) comprises
10% to 92.5% by weight of component (A),
7.5% to 30% by weight of component (B),
0% to 20% by weight of component (C) and
0% to 40% by weight of component (D), based in each case on the total weight of the sinter powder (SP).
7. The sinter powder (SP) according to any of claims 1 to 6, wherein component
(C) is selected from the group consisting of antinucleating agents, impact modifiers, flame retardants, stabilizers, conductive additives, end group functionalizers, dyes, antioxidants, nucleating agents and colour pigments.
8. The sinter powder (SP) according to any of claims 1 to 7, wherein component
(D) is selected from the group consisting of carbon nanotubes, carbon fibres, boron fibres, glass fibres, glass beads, silica fibres, ceramic fibres, basalt fibres, aluminosilicates, magnesium silicates, calcium carbonates, cellulose, lignin, aramid fibres and polyester fibres, preferably aluminosilicates, glass fibres, glass beads, silica fibres and carbon fibres, more preferably aluminosilicates, glass fibres, glass beads and carbon fibres.
9. The sinter powder (SP) according to any of claims 1 to 8, wherein the sinter powder (SP) has a median particle size (D50) in the range from 40 to 80 μm.
10. The sinter powder (SP) according to any of claims 1 to 9, wherein the sinter powder (SP) has a D10 in the range from 10 to 60 μm, a D50 in the range from 40 to 80 μm and a D90 in the range from 50 to 150 μm.
11. A method of producing a shaped body, comprising the steps of: i) providing a layer of the sinter powder (SP) according to any of claims 1 to 10, ii) exposing the layer of the sinter powder (SP) provided in step i) in order to form the shaped body.
12. A shaped body obtained by the method according to claim 11.
13. The use of the sinter powder (SP) according to any of claims 1 to 10 in a sintering method, preferably in a selective laser sintering method (SLS), a highspeed sintering method (HSS) or a multi-jet fusion method (MJF).
14. A method of producing the sinter powder (SP) according to any of claims 1 to 10, comprising the steps of (A) at least one polylactide,
(B) at least one polycaprolactone,
(C) optionally at least one additive, and/or
(D) optionally at least one reinforcer, in an extruder to obtain an extrudate (E) comprising components (A) and (B), and optionally (C) and/or (D), b) pelletizing the extrudate (E) obtained in step a) to obtain a granulate (G) comprising components (A) and (B), and optionally (C) and/or (D), c) micronizing the granulate (G) obtained in step b) to obtain the sinter powder (SP). The use of at least one polycaprolactone (B) in a sinter powder (SP) comprising at least one polylactide (A) for improving the mechanical properties of shaped bodies made from said sinter powder (SP).
PCT/EP2022/071583 2021-08-09 2022-08-01 Sinter powder (sp) comprising at least one polylactide and at least one polycaprolactone WO2023016848A1 (en)

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