Microparticles for use as flowing agents in 3D printing applications

Abstract

The present invention refers to a composition for 3D printing comprising or consisting of i) a powder comprising of polymer particles selected from at least one caprolactone based polymer and / or at least one dioxanone based polymer, and ii) polymer particles selected from at least one lactide based polymer and / or at least one caprolactone based polymer, which have a different particle size than the particles of the powder of i), and iii) optionally at least one additive. Furthermore, the present invention refers to a process for manufacturing the composition of the invention comprising the steps: I) providing a powder comprising of polymer particles selected from at least one caprolactone based polymer and / or at least one dioxanone based polymer, and II) providing polymer particles selected from at least one lactide based polymer and / or at least one caprolactone based polymer, which have a different particle size than the particles of the powder of I), and III) optionally providing at least one additive, and IV) blending the powder of I) and the particles of II) and the optionally at least one additive of III). In addition the present invention refers to the use of the polymer particles selected from at least one lactide based polymer and / or at least one caprolactone based polymer, wherein the particle size distribution D50 is 1 to 10 µm obtained via sieving, as flowing agent in 3D printing applications.

Description

[0001] 202100343 1

[0002] Microparticles for use as flowing agents in 3D printing applications

[0003] Field of the invention

[0004] The present invention refers to a composition for 3D printing comprising or consisting of i) a powder comprising of polymer particles selected from at least one caprolactone based polymer and / or at least one dioxanone based polymer, and ii) polymer particles selected from at least one lactide based polymer and / or at least one caprolactone based polymer, which have a different particle size than the particles of the powder of i), and iii) optionally at least one additive.

[0005] Furthermore, the present invention refers to a process for manufacturing the composition of the invention comprising the steps:

[0006] I) providing a powder comprising of polymer particles selected from at least one caprolactone based polymer and / or at least one dioxanone based polymer, and

[0007] II) providing polymer particles selected from at least one lactide based polymer and / or at least one caprolactone based polymer, which have a different particle size than the particles of the powder of I), and

[0008] III) optionally providing at least one additive, and

[0009] IV) blending the powder of I) and the particles of II) and the optionally at least one additive of III). In addition the present invention refers to the use of the polymer particles selected from at least one lactide based polymer and / or at least one caprolactone based polymer, wherein the particle size distribution D50 is 1 to 10 pm obtained via sieving, as flowing agent in 3D printing applications.

[0010] Description of the related art

[0011] Selective laser sintering (SLS) trends are focusing on solving more and more personalized cases with individual solutions. Bioresorbable polymers that have been cryo-milled are known in the art for SLS. For improving the flow properties, flowing agents such as p-TCP, hydroxyl apatite, bioactive glass, metal alloys or salts such as NaCI have been used. However, in some cases it is not desired to use such flowing agents or even to use any material beside the base polymer.

[0012] The inventors of the present invention surprisingly found that microparticles selected from at least one lactide based polymer and / or at least one caprolactone based polymer can replace commonly known flowing agents. Based on this finding, the inventors found a composition for 3D printing comprising or consisting of a powder comprising of polymer particles selected from at least one caprolactone based polymer and / or at least one dioxanone based polymer, and polymer particles selected from at least one lactide based polymer and / or at least one caprolactone based polymer, which have a different particle size than the particles of the powder, and optionally at least one additive. 202100343 2

[0013] Summary

[0014] In a first aspect the present invention refers to a composition for 3D printing comprising or consisting of i) a powder comprising of polymer particles selected from at least one caprolactone based polymer and / or at least one dioxanone based polymer, and ii) polymer particles selected from at least one lactide based polymer and / or at least one caprolactone based polymer, which have a different particle size than the particles of the powder of i), and iii) optionally at least one additive.

[0015] In a second aspect the present invention pertains to a process for manufacturing the composition of the invention comprising the steps:

[0016] I) providing a powder comprising of polymer particles selected from at least one caprolactone based polymer and / or at least one dioxanone based polymer, and

[0017] II) providing polymer particles selected from at least one lactide based polymer and / or at least one caprolactone based polymer, which have a different particle size than the particles of the powder of I), and

[0018] III) optionally providing at least one additive, and

[0019] IV) blending the powder of I) and the particles of II) and the optionally at least one additive of III).

[0020] In a third aspect the present invention refers to the use of the polymer particles selected from at least one lactide based polymer and / or at least one caprolactone based polymer, wherein the particle size distribution D50 is 1 to 10 pm obtained via sieving, as flowing agent in 3D printing applications.

[0021] These and other aspects, embodiments, features, and advantages of the invention will become apparent to a person skilled in the art through the study of the following detailed description and claims. Any feature from one aspect of the invention can be used in any other aspect of the invention. Furthermore, it will readily be understood that the examples contained herein are intended to describe and illustrate the invention but not to limit the invention and that, in particular, the invention is not limited to these examples.

[0022] Detailed description

[0023] Numerical ranges that are indicated in the format “from x to y” also include the stated values. If several preferred numerical ranges are indicated in this format, it is self-evident that all ranges that result from the combination of the various endpoints are also included.

[0024] "At least one" means one or more, i.e. 1 , 2, 3, 4, 5, 6, 7, 8, 9 or more. "At least one", as used herein in relation to any component, refers to the number of chemically different molecules, i.e. to the number of different types of the referenced species, but not to the total number of molecules. For example, "at least one additive" means that at least one type of molecule falling within the definition for an additive is used 202100343 3 but that also two or more different types of additive falling within this definition can be present but does not mean that only one or more molecules of one type of additive are present.

[0025] All percentages given herein in relation to the compositions or formulations relate to wt.% relative to the total weight of the respective composition, if not explicitly stated otherwise.

[0026] In the following, “selective laser sintering” is referred to as “SLS” as well.

[0027] As used herein, the term “flow function” is defined as the relationship between the strength and the degree of compaction.

[0028] In particular the present invention refers to:

[0029] A composition of the present invention, suitable for 3D printing, comprises or consists of i) a powder comprising of polymer particles selected from at least one caprolactone based polymer and / or at least one dioxanone based polymer, and ii) polymer particles selected from at least one lactide based polymer, which have a different particle size than the particles of the powder of i), and iii) optionally at least one additive.

[0030] In an embodiment the at least one caprolactone based polymer of i) is preferably selected from poly(caprolactone) and / or a poly(lactide-co-caprolactone) and / or mixtures thereof and / or the at least one dioxanone based polymer is selected from polydioxanone and / or the at least one lactide based polymer is poly(L-lactide).

[0031] In an embodiment the at least one caprolactone based polymer and / or the at least one dioxanone based polymer and / or the at least one lactide based polymer have a weight average molecular weight of 5.000 to 140.000 g / mol, preferably 5.000 to 120.000 g / mol, more preferably 10.000 to 100.000 g / mol measured via GPC using polystyrene standards.

[0032] In an embodiment the at least one caprolactone based polymer and / or the at least one dioxanone based polymer and / or the at least one lactide based polymer have an inherent viscosity of 0.1 to 2.5 dL / g, preferably 0.5 to 2.5 dL / g or 0.8 to 2.0 dL / g in CHCh at 25°C measured with a Ubbelhode size 0c glass capillary viscometer.

[0033] In an embodiment the weight of the powder comprising polymer particles i) is 80 to 98 wt%, preferably 85 to 93 wt%, more preferably 85 to 90 wt% and / or the weight of the polymer particles of ii) is 2 to 20 wt%, preferably 5 to 18 wt%, more preferably 7 to 15 wt% and / or the weight of the optionally at least one additive is up to 5 wt%, preferably 1 to 5 wt% wherein the total weight of the components is 100 wt%.

[0034] In an embodiment the powder comprises polymer particles selected from at least one caprolactone based polymer. 202100343 4

[0035] In an embodiment the powder comprises polymer particles selected from at least one dioxanone based polymer.

[0036] In an embodiment the powder comprises polymer particles selected from at least one caprolactone based polymer and / or at least one dioxanone based polymer, wherein the weight ratio of the at least one caprolactone based polymer to the at least one dioxanone based polymer is 1 :5 to 5:1 , preferably 1 :4 to 4:1.

[0037] In an embodiment the particle size distribution D50 of the polymer particles of the powder of i) is larger than the particle size distribution D50 of the polymer particles of ii).

[0038] In an embodiment the particle size distribution D50 of the polymer particles of the powder of i) is 40 to 70 pm, preferably 50 to 70 pm, more preferably 55 to 70 pm obtained via cryogenic micronization using a suitable mill (i.e. pin-mill) and afterwards a sieving step, where over corn and under corn (too large and too small) particles are sieved.

[0039] The measurement of the particle size distribution was performed according to ISO 13320 (2020) using a Malvern Mastersizer 3000, which is a laser scattering equipment that can measure the particle size using air or water as medium.

[0040] In an embodiment the particle size distribution D50 of the polymer particles of ii) is 1 to 10 pm, preferably 1-7 pm, more preferably 1-5 pm, obtained via sieving.

[0041] Preferably, the polymer particles of the powder of i) and the polymer particles of ii) are spherical.

[0042] In an embodiment the difference between the particle size distribution D50 of the polymer particles of the powder of i) and the particle size distribution D50 of the polymer particles of ii) is 30 to 69 pm, preferably 43 to 69 pm, more preferably 50 to 69 pm.

[0043] In an embodiment the flow function of the powder of i) is 3 to 50, preferably 3 to 15, more preferably 4 to 10, most preferably 4 to 7, measured via powder rheological measurements.

[0044] The flow functions are obtained from powder-rheological (also commonly referred as tribological) measurements near the melting point of the respective polymer. The flow functions are obtained from the Mohr’s stress diagram at 3, 6 and 9 kPa resulting in an average flow function.

[0045] In an embodiment the optionally at least one additive is a flowing agent, which is different from the polymer particles of ii) and / or selected from polylactide-co-glycolide, polylactide or a mixture thereof

[0046] In an embodiment the melting temperature of the powder of i) is 50 to 70 °C, preferably 52 to 68 °C, more preferably 55 to 65 °C and / or the melting temperature of the polymer particles of ii) is 150 to 230 °C, 202100343 5 preferably 160 to 220 °C, more preferably 170 to 210 °C measured via differential scanning calorimetry. The skilled person knows the differential scanning calorimetry and knows how to use this method.

[0047] Furthermore the present invention provides a process for manufacturing the composition according to the invention, comprising the following steps

[0048] I) providing a powder comprising of polymer particles selected from at least one caprolactone based polymer and / or at least one dioxanone based polymer, and

[0049] II) providing polymer particles selected from at least one lactide based polymer, which have a different particle size than the particles of the powder of I), and

[0050] III) optionally providing at least one additive, and

[0051] IV) blending the powder of I) and the particles of II) and the optionally at least one additive of III).

[0052] The above mentioned embodiments of the composition according to the invention apply as well to the mentioned process of the invention.

[0053] In an embodiment the powder of step I) and / or the particles of step II) are obtained via milling, wherein milling is preferably performed by micronizing or cryogenic milling, and subsequent sieving of the respective polymers. The skilled person is aware of these methods of milling and knows how to use them in order to obtain the powder of step I) and the particles of step II).

[0054] The skilled person knows techniques for blending a powder, particles and additives.

[0055] Additionally the present invention provides the use of the polymer particle of ii) as flowing agent in 3D printing applications.

[0056] In a preferred embodiment the 3D printing application is SLS.

[0057] SLS 3D printing methods are known in the art. SLS can be performed on a blade based (e.g. EOS P series) machine. The technique produces physical parts through a selective solidification of a variety of fine powders. SLS builds up parts layer by layer using powders which are selectively bonded when a laser beam scans the powder across each layer’s cross-sectional area. Typical laser energy densities are from 7 kJ / m2 to 60 kJ / m2. SLS fuses thin layers of powder (typically ~0.1 mm of thickness) which have been spread across the build area using a blade. Building of parts takes place inside an enclosed chamber filled with an inert gas, preferably nitrogen gas, to minimize oxidation and degradation of the powdered material. The powder in the build platform is maintained at an elevated temperature just below the melting point (for semi-crystalline polymer only) of the powdered material.

[0058] Examples to the invention 202100343 6

[0059] Poly(caprolactone) or poly(dioxanone) were micronized into a powder with a particle size distribution D50 of 40 to 70 pm. Subsequently, poly(L-lactide) was micronized into particles with a particle size distribution D50 of 1 to 10 pm. Different amounts of the particles (3 wt%, 4 wt%, 5 wt%, 10 wt% and 20 wt%) were blended with the powder.

[0060] Example 2: Flowing of different compositions

[0061] The flowability of the compositions 1 and 2 of the invention were investigated and compared to the flowability of the compositions 3 and 4, which served as comparative examples. The flowability was measured using a tribometer (Anton Paar Germany GmbH) and a shear cell. The flowability of the compositions 1 and 2 of the invention was improved compared to the flowability of the compositions 3 and 4. This was evaluated visually.

Claims

202100343 7Claims1 . A composition suitable for 3D printing comprising or consisting of i) a powder comprising polymer particles selected from at least one caprolactone based polymer and / or at least one dioxanone based polymer, and ii) polymer particles selected from at least one lactide based polymer, which has a different particle size than the particles of the powder i), and iii) optionally at least one additive.

2. The composition according to claim 1 , wherein the at least one caprolactone based polymer is selected from poly(caprolactone) and / or a poly(lactide-co-caprolactone) and / or mixtures thereof and / or the lactide based polymer is poly(L-lactide) and / or the at least one dioxanone based polymer is poly(dioxanone).

3. The composition according to any of the preceding claims, wherein the at least one caprolactone based polymer and / or the at least one lactide based polymer and / or the at least one dioxanone based polymer have a weight average molecular weight of 5.000 to 140.000 g / mol, measured via GPC using polystyrene standards.

4. The composition according to any of the preceding claims, wherein the weight of the powder i) is 80 to 98 wt% and / or the weight of the polymer particles of ii) is 2 to 20 wt% and / or the weight of the optionally at least one additive is up to 5 wt%, wherein the total weight of the composition is 100 wt%.

5. The composition according to any of the preceding claims, wherein the particle size distribution D50 of the polymer particles of the powder is 40 to 70 pm, obtained via sieving.

6. The composition according to any of the preceding claims, wherein the particle size distribution D50 of the polymer particles of ii) is 1 to 10 pm, obtained via sieving.

7. The composition according to any of the preceding claims, wherein the difference between the particle size distribution D50 of the polymer particles of the powder and the particle size distribution D50 of the polymer particles of ii) is 30 to 69 pm.

8. The composition according to any of the preceding claims, wherein the flow function of the powder is 3 to 50, measured via powder rheological measurement.

9. The composition according to any of the preceding claims, wherein the optionally at least one additive is a flowing agent, which is different from the polymer particles of ii).202100343 810. The composition according to any of the preceding claims, wherein the melting temperature of the powder of i) is 50 to 70 °C and / or the melting temperature of the polymer particles of ii) is 150 to 230 °C measured via differential scanning calorimetry.

11. A process for manufacturing the composition according to any of claims 1 to 10, comprising the following stepsI) providing a powder comprising of polymer particles selected from at least one caprolactone based polymer and / or at least one dioxanone based polymer, andII) providing polymer particles selected from at least one lactide based polymer, which have a different particle size than the particles of the powder of I), andIII) optionally providing at least one additive, andIV) blending the powder of I) and the particles of II) and the optionally at least one additive of III).

12. The process according to claim 11 , wherein the powder of step I) and / or the particles of step II) are obtained via milling, wherein milling is performed by micronizing or cryogenic milling, and subsequent sieving of the respective polymers.

13. Use of the polymer particles selected from at least one lactide based polymer, wherein the particle size distribution D50 is 1 to 10 pm obtained via sieving, as flowing agent in 3D printing applications.

14. Use of the polymer particles according to claim 13, wherein the 3D printing application is selective laser sintering.

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