ADDITIVE MANUFACTURING PROCESS USING A BUILDING MATERIAL THAT CONTAINS METAL-OXIDE COATED MICA

Abstract

The present invention relates to a method of producing an article, comprising the step of producing the article by means of an additive manufacturing method from a build material comprising an aromatic polycarbonate and interference pigments and/or pearlescent pigments from the group of the metal oxide-coated micas. The invention likewise relates to an article obtainable by the method. The build material further comprises ≥0.05% by weight to ≤3% by weight of anhydride-modified α-olefin polymer.

Claims

1.-15. (canceled)

16. A method of producing an article, comprising producing the article by means of an additive manufacturing method from a build material, wherein the build material, based on the total weight of the build material, comprises A) ≥50% by weight to ≤98.5% by weight of aromatic polycarbonate, B) ≥0.8% by weight to ≤3.0% by weight of interference pigment and/or pearlescent pigment from the group of metal oxide-coated micas and C) ≥0.05% by weight to ≤3% by weight of anhydride-modified α-olefin polymer, where the sum total of the percentages by weight of A), B) and C) is ≤100% by weight.

17. The method as claimed in claim 16, wherein the build material A) comprises a polycarbonate having a weight-average molecular weight M.sub.w of ≥10 000 to ≤40 000 g/mol, determined by gel permeation chromatography in methylene chloride at 25° C. against polycarbonate standards.

18. The method as claimed in claim 17, wherein the pearlescent pigment and/or interference pigment B) from the group of the metal oxide-coated micas present is anatase- or rutile-coated mica.

19. The method as claimed in claim 16, wherein the anhydride-modified α-olefin polymer C) has been modified with maleic anhydride and is based on ethene, propene and/or 1-octene.

20. The method as claimed in claim 16, wherein the anhydride-modified α-olefin polymer C) has an average molecular weight M.sub.w, determined by means of gel permeation chromatography in ortho-dichlorobenzene at 150° C. with polystyrene calibration, of ≥1000 to ≤15 000 g/mol and an acid number of ≥45 to ≤170 mg KOH/g, determined to DIN ISO 17025:2018-03 by means of potentiometric titration.

21. The method as claimed in claim 16, wherein the build material further comprises D) ≥0.001% by weight to ≤0.500% by weight, based on the total weight of the build material, of one or more phosphorus-containing thermal stabilizers, and the sum total of the percentages by weight of A), B), C) and D) is ≤100% by weight.

22. The method as claimed in claim 16, wherein the build material further comprises E) >0% by weight to ≤7% by weight, based on the total weight of the build material, of further additives selected from the group consisting of flame retardants, anti-dripping agents, thermal stabilizers other than component D), impact modifiers, fillers, antistats, colorants, pigments other than component B, also including carbon black, lubricants, demolding agents, hydrolysis stabilizers, compatibilizers, UV absorbers and/or IR absorbers, and the sum total of the percentages by weight of A), B), C), D) and E) is ≤100% by weight.

23. The method as claimed in claim 16, wherein the production of the article by the additive manufacturing method comprises the steps of: applying a layer of particles including the build material to a target surface; introducing energy into a selected portion of the layer corresponding to a cross section of the article such that the particles in the selected portion are bonded; repeating the steps of applying and introducing energy for a multitude of layers, such that the bonded portions of the adjacent layers become bonded in order to form the article.

24. The method as claimed in claim 16, wherein the production of the article by the additive manufacturing method comprises the steps of: applying a filament of an at least partly molten build material to a carrier, such that a layer of the build material is obtained, corresponding to a first selected cross section of the article; applying a filament of the at least partly molten build material to a previously applied layer of the build material, such that a further layer of the build material is obtained, which corresponds to a further selected cross section of the article and which is bonded to the layer applied beforehand; repeating the step of applying a filament of the at least partly molten build material to a previously applied layer of the build material until the article has been formed.

25. The method as claimed in claim 16, wherein the method is conducted within a build chamber and the temperature of the build chamber is ≥10° C. lower than the glass transition temperature T.sub.g of the build material (determined by DSC to ISO 11357-2:2013-05 at a heating rate of 10° C./min).

26. The method as claimed in claim 16, wherein the surface temperature of a layer of the build material applied last in the additive manufacturing method is not less than a temperature which, in a dynamic-mechanical analysis of the build material (to ISO 6721-10:2015-09 at an angular frequency of 1/s), corresponds to a point of intersection of a theoretical straight line in the section of the curve of the storage modulus E′ corresponding to a vitreous state of the build material and a theoretical straight line in the section of the curve of the storage modulus E′ in which the storage modulus E′ declines and indicates a glass transition.

27. The method as claimed in claim 16, wherein a multitude of build materials is used, and at least one of the build materials is as defined in claim 16.

28. An article obtained by a method as claimed in claim 16, wherein the article is at least partly produced from a build material as defined in claim 16, and wherein the article, in build direction of the additive manufacturing method used in the production thereof, has a tensile strength (ISO 527:2012-02) of ≥30% to <100% of the tensile strength (ISO 527:2012-02) of an injection-molded test specimen made of the same build material.

29. The article as claimed in claim 28, wherein the article comprises a multitude of build materials, and at least one of the build materials does not comprise component b).

30. The article as claimed in claim 28, wherein the article is a housing, a prosthesis, a lampshade, a reflector or a decorative cover.

Description

EXAMPLES

[0188] The invention is illustrated in detail by working examples hereinafter, without restriction thereto. The methods of determination described here are employed for all corresponding parameters in the present invention, in the absence of any statement to the contrary.

[0189] For the Charpy impact resistance tests (ISO 179 1 e U), flat specimens having dimensions of 80 mm×10 mm×4 mm were produced by the FDM method. Production conditions: nozzle diameter: 0.4 mm; print speed: 38 mm/s; layer thickness: 0.2 mm; nozzle temperature: 295° C.; print bed temperature: 100° C. The measurements were effected at 23° C.

[0190] For the tensile tests according to ISO 527-2:2012-02, corresponding S2 specimens were likewise produced by the FDM method. The build direction in each case is the Z direction.

[0191] The molecular weight was determined by means of gel permeation chromatography to DIN 55672-1:2007-08, calibrated against bisphenol A polycarbonate standards and using dichloromethane as eluent, by method 2301-0257502-09D (from 2009, in German) from Currenta GmbH & Co. OHG, Leverkusen; column combination of crosslinked styrene-divinylbenzene resins. Diameter of analytical columns: 7.5 mm; length: 300 mm. Particle sizes of column material: 3 μm to 20 μm. Concentration of solutions: 0.2% by weight. Flow rate: 1.0 ml/min, temperature of solutions: 30° C. Detection using a refractive index (RI) detector.

[0192] The build material for experiment no. 1-1 had the following composition: 97.51% by weight of an aromatic polycarbonate having Mw of about 24 000 g/mol, 0.08% by weight of a phosphite thermal stabilizer, 0.02% by weight of a phenolic antioxidant, 0.4% by weight of a maleic anhydride-modified polyolefin, 1.94% by weight of effect pigment based on TiO.sub.2- and Fe.sub.2O.sub.3-coated mica and 0.05% by weight of organic colorant composition.

[0193] The build material for comparative experiment no. V-1 had the following composition: 97.48% by weight of an aromatic polycarbonate having Mw of about 31 000 g/mol, 0.4% by weight of an organic lubricant and demolding agent, 1.94% by weight of effect pigment based on TiO.sub.2-coated mica and 0.18% by weight of organic colorant composition.

[0194] The build material for experiment no. 2-1 had the following composition: 97.38% by weight of an aromatic polycarbonate having Mw of about 31 000 g/mol, 0.08% by weight of a phosphite thermal stabilizer, 0.02% by weight of a phenolic antioxidant, 0.4% by weight of a maleic anhydride-modified polyolefin, 1.94% by weight of effect pigment based on TiO.sub.2-coated mica and 0.18% by weight of organic colorant composition.

TABLE-US-00001 Plane of examination of Experiment No. the test specimen 1-1 1-1 1-1 V1 V1 V1 2-1 2-1 2-1 Test Unit X/Y Y/Z Z/Y X/Y Y/Z Z/Y X/Y Y/Z Z/Y Charpy Number of test specimens: 5/0 5/0 5/0 5/0 5/0 5/0 3/2 3/2 5/0 broken/unbroken Average of broken test kJ/m.sup.2 76 138 9 46 69 8 66 165 10 specimens Tensile test Modulus of elasticity N/mm.sup.2 1510 923 1720 1060 2070 1300 Tensile strength N/mm.sup.2 42 17 49 22 57 28 Elongation at break % 6.5 3.1 8.5 3 8.5 3.1 GPC of material samples of the test specimens M.sub.n g/mol 10320 10110 11650 M.sub.w g/mol 23810 28170 31160 M.sub.z g/mol 38420 47560 51090 M.sub.w/M.sub.n 2.30 2.78 2.67

[0195] It can be seen that a distinct reduction in polymer degradation was achievable in the case of test specimens of the invention. The formulations equipped with the novel stabilizers show virtually no breakdown in spite of repeated melting. A distinct increase in toughness is also found in the formulations of the invention compared to the standard formulation.