Mechanically stable core-shell fdm prints containing porous cores

Abstract

The invention provides a method for producing a 3D item by means of fused deposition modeling, the method comprising: (a) a 3D printing stage comprising: depositing a 3D printable material layer by layer, wherein the 3D printable material comprises a 3D printable core material and a 3D printable shell material, to provide a 3D item comprising a core-shell layer of 3D printed material, wherein the 3D printed material comprises a core comprising the 3D printed core material and a shell comprising the 3D printed shell material, wherein the shell at least partially surrounds the core, wherein the 3D printable core material comprises a pore-forming material having a first concentration c1, wherein the 3D printable shell material comprises a pore-forming material having a second concentration c2, wherein c2 / c1 < 0.9; and (b) a pore-forming stage comprising: heating one or more of: (i) the printable material and (ii) the 3D printed material.

Description

TECHNICAL FIELD

[0001] The present invention relates to a method for manufacturing a 3D (printed) article. Further, the present invention can relate to a filament for use in such a method. The present invention also relates to a 3D (printed) article obtainable with such a method. Further, the present invention relates to a lighting device comprising such a 3D (printed) article. BACKGROUND

[0002] It is known to introduce pores in FDM printing. For example, EP 3403806 describes a cellular thermoplastic structure with hierarchical multiscale porosity produced by an integrated method of 3D printing, preferably by fused deposition modeling (FDM), and supercritical gas foaming (SCF). Porous filaments or strands and related hierarchical structures are processed in one continuous step. For thermoplastic-based polymers, the influence of printing parameters, e.g. deposition temperature and speed, on the foam morphology and pore distribution is described. The process can be applied to other thermoplastic filaments or strands with different properties. These strands are combined in 3D configurations to produce hierarchical structures and offer the possibility to fine-tune the cellular morphology in different scales in a continuous manner.

[0003] WO-2020 / 048889 discloses a method of producing a 3D article by means of fused deposition modeling. The method has a 3D printing phase and an exposure phase. During the 3D printing phase, the extrudate comprises a core-shell extrudate having a core of a core material and a shell of a shell material. During the exposure phase, at least a portion of a surface of the 3D article is exposed to a liquid, wherein the core material has a lower solubility in the liquid than the shell material.

[0004] WO-2016 / 187097 discloses a foamed ink composition for printing a porous structure, comprising stable particles and gas bubbles dispersed in a solvent. The stable particles comprise a predetermined interfacial energy so as to exhibit a contact angle with the solvent from about 15° to about 90°. At least a portion of the stable particles are positioned in an interfacial region between the solvent and the gas bubbles, thereby stabilizing the gas bubbles in the foamed ink composition. A 3D printed hierarchical porous structure comprises one or more continuous filaments arranged in a predetermined pattern on a substrate, the one or more continuous filaments comprising a sinterable material and comprising a porosity with a volume fraction of at least about 40%. SUMMARY

[0005] In the coming 10-20 years, digital manufacturing will increasingly transform the nature of global manufacturing. One aspect of digital manufacturing is 3D printing. Currently, many different techniques have been developed in order to produce various 3D printed objects using various materials such as ceramics, metals and polymers. 3D printing can also be used to produce a mold which can then be used to replicate an object.

[0006] For the purpose of manufacturing molds, it has been suggested to use the Polyjet technology. This technology makes use of the layer-by-layer deposition of a photopolymerizable material which is cured after each deposition to form a solid structure. Although this technology produces smooth surfaces, the photopolymerizable materials are not very stable and they also have a relatively low thermal conductivity to be beneficial for injection molding applications.

[0007] The most widely used additive manufacturing technique is a process known as Fused Deposition Modeling (FDM). Fused Deposition Modeling (FDM) is an additive manufacturing technique commonly used for modeling, prototyping, and production applications. FDM works by laying down material in layers, following the "additive" principle; plastic filaments or metal wires are unwound from a coil and drawn through a nozzle to produce parts. Possibly, the filament is melted and extruded before being laid down (e.g. for thermoplastics). FDM is a rapid prototyping technique. Other terms for FDM are "Fused Filament Fabrication" (FFF) or "Filament 3D Printing" (FDP), which are considered equivalent to FDM. Typically, FDM printers use thermoplastic filaments, which are heated to their melting point and then extruded to create three-dimensional objects layer by layer (or actually filament by filament). FDM printers are relatively fast, low cost and can be used to print complex 3D objects. Such printers are used to print various shapes using various polymers. The technology is further developed in the production of LED luminaires and lighting solutions.

[0008] It is therefore an aspect of the present invention to provide an alternative 3D printing method and / or 3D (printed) article, which preferably further at least partially obviates one or more of the above-mentioned disadvantages. It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide the public with a useful alternative.

[0009] Thus, in a first aspect, the present invention provides a method for producing a 3D article by means of fused deposition modeling. In particular, the method can comprise a 3D printing phase comprising depositing a 3D printable material layer by layer. In embodiments, the 3D printable material can comprise a 3D printable core material and a 3D printable shell material to provide a 3D article. The 3D article comprises (thereby) a core-shell layer of 3D printed material. In particular, the 3D printed material comprises a core comprising the 3D printed core material and a shell comprising the 3D printed shell material, wherein the shell can at least partially surround the core. In embodiments, the 3D printable core material can comprise a pore-forming material having a first concentration ci, and the 3D printable shell material can comprise a pore-forming material having a second concentration c2. In particular, c2 / ci < 0.9. In particular, the method can further comprise a pore-forming phase comprising heating one or more of: (i) the printable material and (ii) the 3D printed material to induce pore formation. The 3D printing phase and the pore-forming phase can overlap in time or even be substantially identical. Thus, in specific embodiments, the present invention provides a method for producing a 3D article by means of fused deposition modeling, the method comprising: (a) a 3D printing phase comprising: depositing a 3D printable material layer by layer, wherein the 3D printable material comprises a 3D printable core material and a 3D printable shell material to provide a 3D article comprising a core-shell layer of 3D printed material, wherein the 3D printed material comprises a core comprising the 3D printed core material and a shell comprising the 3D printed shell material, wherein the shell at least partially surrounds the core, wherein the 3D printable core material comprises a pore-forming material having a first concentration ci, wherein the 3D printable shell material comprises a pore-forming material having a second concentration c2, wherein c2 / ci < 0.9; and (b) a pore-forming phase comprising: heating one or more of: (i) the printable material and (ii) the 3D printed material.

[0010] In this way, a porous 3D printed article can be prepared by means of FDM while reducing the amount of material used, thus reducing the weight of the printed object, while maintaining the structural integrity and smooth surface structure of the printed article. This is achieved by printing a porous core and a non-porous shell.

[0011] In embodiments, the shell completely surrounds the core (in cross-section), thus providing a smooth surface on each layer. To further exploit the advantage of weight reduction, the amount of shell can be minimized. In specific embodiments, the shell can partially surround the core. Using this method, the shell can surround the core only at areas that will become the exterior of the 3D printed article. Thus, there can be no shell between the cores of adjacent layers.

[0012] To facilitate pore formation, the 3D printable material comprises a thermoplastic material and a pore-forming material embedded therein. The pore-forming material can expand during a pore-forming phase and thus create pores within the 3D printable or 3D printed material. In particular, in embodiments, the pore-forming material is heat sensitive. Pores can be formed due to evaporation and / or expansion of the pore-forming material, such as in case the embedded water is heated beyond its boiling point.

[0013] The porosity can depend on the type of pore-forming material and the concentration of the pore-forming material. The porosity can be determined via direct methods, such as in particular determining the total volume of the porous sample and then determining the volume of the skeleton material without pores (pore volume = total volume - material volume). Alternatively, the porosity can be determined via optical methods, such as in particular determining the area of the material in relation to the area of the pores visible under a microscope. For porous media with a random structure, the “area” and “volume” porosities can be essentially equal. Similarly, the pore diameter can be determined via optical methods, such as in particular measuring the size of the pores visible under a microscope. Alternatively, the porosity can be determined in particular using mercury intrusion porosimetry. Alternatively, in particular X-ray tomography can be applied. The pore diameter of spherical pores can be defined by their diameter. For irregularly shaped pores, an equivalent spherical diameter can be determined. The equivalent spherical diameter (or ESD) of a (irregularly shaped) object is the diameter of a sphere with the same volume. The equivalent circular diameter (or ECD) of a (irregularly shaped) two-dimensional shape is the diameter of a circle with the same area. For example, the equivalent circular diameter of a square with side a is 2*a*SQRT(l / π). For a circle, the diameter and the equivalent circular diameter are the same. If a circle with diameter D in the xy-plane is deformed into any other shape (in the xy-plane) without changing the size of the area, then the equivalent circular diameter of that shape will be D.

[0014] In embodiments, the porosity of the printed core material in the core-shell layer can be in the range of 5-60% by volume, in particular in the range of 5-50% by volume, more in particular in the range of 5-40% by volume, such as less than 40% by volume, more in particular less than 35% by volume.

[0015] The pore-forming material can be a single pore-forming material or a plurality of pore-forming materials. The proportion of individual pore-forming materials in a mixture of pore-forming materials can deviate from the total proportion of pore-forming materials between the core and the shell. Thus, in specific embodiments, a particular pore-forming material a having a first concentration ca1 in the core and a second concentration ca2 in the shell can comply with ca2 / ca1 > 1. However, the total concentration of pore-forming materials in the core c1 is greater than the total concentration of pore-forming materials in the shell c2. Thus c2 / c1 < 0.9, in particular c2 / c1 < 0.8, more particularly c2 / c1 < 0.6, in embodiments c2 / c1 < 0.3, c2 / c1 < 0.1, more particularly c2 / c1 < 0.05. In particular c2 / c1 < 0.01, more particularly c2 / c1 < 0.001

[0016] Thus, in embodiments, the shell printable material essentially does not contain any pore-forming material (i.e. its concentration can essentially be zero).

[0017] In embodiments, the pore-forming material in the core printable material and the pore-forming material in the shell printable material is one of the following pore-forming materials: (i) the same pore-forming material or the same pore-forming material in the same proportion, (ii) the same pore-forming material in different proportions, or (iii) different pore-forming materials. In specific embodiments, one pore-forming material (or a plurality of pore-forming materials) can have a boiling point above room temperature.

[0018] In embodiments, the pore-forming material can be a liquid at room temperature and a gas at the extrusion temperature (i.e. the temperature at which the 3D printable material is extruded from the printer nozzle). In particular, the pore-forming material has a boiling point between room temperature and 250 °C, more particularly the pore-forming material has a boiling point between room temperature and 90-240 °C. During the pore-forming phase, the pore-forming material is heated above its boiling point, which can lead to pore formation. In particular, the nozzle temperature is above the boiling point of the pore-forming material.

[0019] In embodiments, wherein the pore-forming material can comprise a plurality of pore-forming materials, the pore-forming material (i.e. the combination of pore-forming materials) can have a boiling range. In particular, the nozzle temperature can then be chosen above the start of the boiling range.

[0020] Materials which can be particularly suitable as pore-forming materials can be selected from the group of water and hydrocarbons, in particular alkanes and alkenes. Suitable alkanes can include one or more of the group of (i) pentane, (ii) hexane, (iii) heptane and (iv) octane. Suitable alkenes can include one or more of the group of (i) pentene, (ii) hexene, (iii) heptene, (iv) octene and (v) nonene; however, other suitable hydrocarbons can also apply. Thus, also combinations of two or more can be used, such as pentene and hexene, or pentene and heptane, etc.

[0021] The pore forming material can comprise water. In embodiments c2< 0.25wt%, in particular c2< 0.1wt%, more in particular c2< 0.04wt%. In embodiments c2< 0.03wt%, in particular embodiments c2< 0.02wt%. In embodiments, the pore forming material comprises water and the pore forming stage comprises applying one or more of the following to the core-shell 3D printed layer: (i) microwave radiation and (ii) ultrasound.

[0022] The pore forming material can comprise pentene. In embodiments c2< 0.15wt%, in particular c2< 0.06wt%, more in particular c2< 0.025wt%. In embodiments c2< 0.02wt%, in particular embodiments c2< 0.015wt%.

[0023] In embodiments, cl > 0.01wt%, even more in particular cl > 0.02wt%, still even more in particular cl > 0.03wt%. Further, in embodiments cl > 0.1wt%, such as cl > 0.25wt%, like in embodiments cl > 0.03wt%. In yet other embodiments, cl < 1wt%.

[0024] Thus, in embodiments 0.01wt% < cl < 1wt%, in particular 0.05wt% < cl < 0.5wt% and c2< 0.04wt%, wherein c2 / cl < 1, in particular wherein c2 / cl < 0.9.

[0025] When two or more different pore forming materials are available in the 3D printable core material, in particular the total weight of the pore forming materials can comply with 0.01wt% < cl < 1wt%, in particular 0.05wt% < cl < 0.5wt% and c2< 0.04wt%, wherein c2 / cl < 1, in particular wherein c2 / cl < 0.9.

[0026] In embodiments, the concentration of the pore forming material can be increased by exposing the printable material to a high vapor concentration of the pore forming material. For example, in embodiments the 3D printable core material can be exposed to humid air, such as air with a RH of at least 75%, like at least 90%.

[0027] In particular, the printable material can be chemically functionalized, e.g. with hydrophilic groups, for retaining a higher concentration of the pore forming material.

[0028] In addition to the pore forming material, the 3D printable material can comprise other additives and / or particles. In embodiments, stabilizers, light absorbing agents, dyes, reflective particles, etc... can be included. This will be described in more detail later.

[0029] The density reduction that can be obtained depends on the choice of several parameters, which can include: the pore-forming material, the first concentration ci, the second concentration c2, and the 3D printing conditions. In embodiments, a density reduction of the core-shell layer of more than 10%, in particular more than 20%, more in particular more than 30% can be obtained compared to the theoretical maximum density that is obtained when no pore-forming material is incorporated in the 3D printable material.

[0030] In embodiments, the method provides a 3D printed article having a core-shell layer, the core-shell layer having a shell with a shell width (W2), and the core-shell layer having a layer width (W); wherein 0.01 < W2 / W < 0.3, in particular wherein 0.02 < W2 / W < 0.3, more in particular wherein 0.03 < W2 / W < 0.2. A smaller shell width W2 can result in a (relatively) higher density reduction, a larger shell width W2 can result in better mechanical properties.

[0031] In embodiments, the method provides a core-shell filament having a shell with a shell width (W2F), wherein the core-shell filament has a width (WF); wherein 0.01 < W2F / WF < 0.3, in particular wherein 0.02 < W2F / WF < 0.3, more in particular wherein 0.03 < W2F / WF < 0.2.

[0032] In embodiments, the core-shell layer can be printed with a core-shell nozzle. In embodiments, the core-shell layer can be obtained from a core-shell filament (such as for example as described above).

[0033] The 3D printing phase and the pore-forming phase can overlap in time or even be substantially the same. In embodiments, the pore-forming material has a boiling temperature, and the method comprises 3D printing the 3D printable material with a nozzle temperature that is higher than the boiling temperature.

[0034] In embodiments, the diameter d of the pores in the core can be in the range of d / W < 0.4, such as in particular embodiments d / H < 0.4. Alternatively or additionally, in embodiments d / W > 0.05, even more in particular d / H > 0.05. Here, H refers to the height of the core-shell layer, and W refers to the width of the core-shell layer. Typically, H < W (see also below).

[0035] In particular embodiments, 50 pm < d < 2 mm, in particular 20 pm < d < 2 mm.

[0036] The pores can be voids, which can be embedded in the 3D printed material.

[0037] In embodiments, the core and the shell are the same thermoplastic material. In particular, the core and the shell comprise polycarbonate.

[0038] As mentioned above, the method comprises depositing a 3D printable material during the printing phase. Herein, the term "3D printable material" refers to the material that will be deposited or printed, and the term "3D printed material" refers to the material obtained after deposition. These materials can be essentially the same, as the 3D printable material can especially refer to the material in the print head or extruder at high temperature, and the 3D printed material refers to the same material, but at a later stage when deposited. The 3D printable material is printed into a filament and deposited as such. The 3D printable material can be provided as a filament or can be formed into a filament. Thus, regardless of the starting material applied, the filament comprising the 3D printable material is provided by the print head and is 3D printed. The term "extrudate" can be used to define the 3D printable material downstream of the print head, but not yet deposited. The latter is indicated as "3D printed material". In fact, the extrudate comprises the 3D printable material, as the material has not yet been deposited. Upon deposition of the 3D printable material or extrudate, the material is thus indicated as 3D printed material. In essence, these materials are the same material as the thermoplastic material upstream of the print head, downstream of the print head, and when deposited, these materials are in essence the same material.

[0039] Herein, the term "3D printable material" can also be indicated as "printable material". The term "polymeric material" can in embodiments refer to a blend of different polymers, but can in embodiments also essentially refer to a single polymer type having different polymer chain lengths. Thus, the term "polymeric material" or "polymer" can refer to a single type of polymer, but can also refer to a plurality of different polymers. The term "printable material" can refer to a single type of printable material, but can also refer to a plurality of different printable materials. The term "printed material" can refer to a single type of printed material, but can also refer to a plurality of different printed materials. The term "pore forming material" can in embodiments refer to a single type of pore forming material but can also refer to a plurality of different pore forming materials.

[0040] Thus, the term "3D printable material" can also refer to a combination of two or more materials. Typically, these (polymeric) materials have a glass transition temperature T g and / or a melting temperature T m . Prior to the 3D printable material leaving the nozzle, the 3D printable material will be heated by the 3D printer to a temperature of at least the glass transition temperature, and typically at least the melting temperature. Thus, in one specific embodiment, the 3D printable material comprises a polymer having a glass transition temperature (T g ) and / or a melting point (T m) and the print head action comprises heating the 3D printable material above the glass transition temperature and, if the 3D printable material is a semi-crystalline polymer, above the melting temperature. In yet another embodiment, the 3D printable material comprises a (thermoplastic) polymer having a melting point (T m ) and the print head action comprises heating the 3D printable material to be deposited on the receiver article to a temperature that is at least the melting point. The glass transition temperature is typically different from the melting temperature. Melting is a transition that occurs in crystalline polymers. Melting occurs when polymer chains fall out of their crystalline structure and become disordered liquids. The glass transition is a transition that occurs in amorphous polymers; i.e. their chains are not arranged in an ordered crystal but are scattered in any way around the surrounding polymer, even though they are in a solid state. Polymers can be amorphous, essentially have a glass transition temperature instead of a melting temperature, or can be (semi-) crystalline, typically both have a glass transition temperature and a melting temperature, wherein typically the latter is greater than the former. The glass temperature can be determined, for example, with differential scanning calorimetry. The melting point or melting temperature can also be determined with differential scanning calorimetry.

[0041] In embodiments, the boiling point of the pore-forming material can be lower than the T g or T m . In specific embodiments, the boiling point of the pore-forming material can be lower than the T g .

[0042] As mentioned above, the present application thus provides a method comprising providing a filament of a 3D printable material and printing said 3D printable material on a substrate during a printing phase to provide said 3D article.

[0043] Thus, in another aspect, the present application provides a filament for producing a 3D article by means of fused deposition modeling. In particular, the filament can comprise a core comprising a printable core material. The printable core material can comprise a first concentration ci of a pore-forming material. The filament can also comprise a shell comprising a printable shell material. The printable shell material can comprise a second concentration c2 of a pore-forming material. In embodiments, c2 / c1 < 0.01, or even lower (see above). In specific embodiments, c2 < 0.04 wt%, or even lower (see above). In embodiments, the shell at least partially surrounds the core.

[0044] Thus, in specific embodiments, the present application provides a filament for producing a 3D item by means of fused deposition modeling, the filament comprising: (i) a core comprising a printable core material, wherein the printable core material comprises a first concentration ci of pore-forming material; and (ii) a shell comprising a printable shell material, wherein the printable shell material comprises a second concentration c2 of pore-forming material; wherein c2 / ci < 0.01, and wherein c2 < 0.04 wt%; wherein the shell at least partially surrounds the core. In particular, in embodiments, the shell completely surrounds the core (in cross-sectional view).

[0045] In this way, a porous 3D printed item can be prepared by means of FDM, starting from a previously prepared filament.

[0046] In particular, in embodiments, the printable material can be chemically functionalized, e.g. functionalized with hydrophilic groups, to retain a higher concentration of pore-forming material.

[0047] In specific embodiments, the filament can comprise: (i) a core comprising a printable core material having a porosity pi, and (ii) a shell comprising a printable shell material having a porosity p2, wherein p2 / pi < 0.9, in particular wherein p2 / pi < 0.8, more in particular wherein p2 / pi < 0.6, in embodiments p2 / pi < 0.3, p2 / pi < 0.1, in particular p2 / pi < 0.05, especially p2 / pi < 0.01, more in particular p2 / pi < 0.001; wherein the shell at least partially surrounds the core.

[0048] Thus, in embodiments, the 3D printed shell material has essentially no porosity (i.e. p2 is essentially zero).

[0049] In specific embodiments, the filament comprises a shell having a shell width (W2F), and the core-shell filament has a width (WF); wherein 0.01 < W2F / WF < 0.3, in particular wherein 0.02 < W2F / WF < 0.3, more in particular wherein 0.03 < W2F / WF < 0.2.

[0050] Materials that can be particularly suitable as 3D printable material can be selected from the group of metals, glass, thermoplastic polymers, silicones, etc. In particular, the 3D printable material comprises a (thermoplastic) polymer selected from the group of ABS (acrylonitrile butadiene styrene), nylon (or polyamide), acetate (or cellulose), PLA (poly lactic acid), terephthalate (such as PET polyethylene terephthalate), acrylic (polymethacrylate, Perspex, polymethyl methacrylate PMMA), polypropylene (or polypropene), polycarbonate (PC), polystyrene (PS), PE (such as expanded-high impact polyethylene (or polyethylene), low density (LDPE) high density (HDPE)), PVC (polyvinyl chloride) polyvinyl chloride, such as thermoplastic elastomers based on co-polyester elastomers, polyurethane elastomers, polyamide elastomers, polyolefin-based elastomers, styrene-based elastomers, etc. Optionally, the 3D printable material comprises a material selected from the group of urea-formaldehyde, polyester resin, epoxy resin, melamine, thermoplastic elastomer, etc. Optionally, the 3D printable material comprises a 3D printable material selected from the group of poly(sulphones). Elastomers - in particular thermoplastic elastomers - are of particular interest as they are flexible and can help to obtain relatively more flexible filaments comprising thermally conductive material. Thermoplastic elastomers can comprise one or more of the following materials: styrenic block copolymers (TPS (TPE-s)), thermoplastic polyolefin elastomers (TPO (TPE-o)), thermoplastic vulcanizates (TPV (TPE-v or TPV)), thermoplastic polyurethanes (TPU (TPU)), thermoplastic co-polyesters (TPC (TPE-E)) and thermoplastic polyamides (TPA (TPE-A)).

[0051] Suitable thermoplastic materials, such as also mentioned in WO2017 / 040893, can include one or more of the following materials: polyacetals (e.g., polyoxymethylene and polyformaldehyde), poly(C 1-6 alkyl) acrylates, polyacrylamides, polyamides (e.g., aliphatic polyamides, polyphthalamides, and polyaramides), polyamide-imides, polyanhydrides, polyarylates, polyarylethers (e.g., polyphenylene ether), polyarylene sulfides (e.g., polyphenylene sulfide), polyarylene sulfones (e.g., polyphenylene sulfone), polybenzothiazoles, polybenzoxazoles, polycarbonates (including polycarbonate copolymers such as polycarbonate-siloxane, polycarbonate-ester, and polycarbonate-ester-siloxane), polyesters (e.g., polycarbonates, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyarylate), and polyester copolymers such as polyester-ether, polyether ether ketone, polyetherimides (including copolymers such as polyetherimide-siloxane copolymers), polyether ketone ketone, polyether ketone, polyether sulfone, polyimides (including copolymers such as polyimide-siloxane copolymers), poly(C1-6 Alkyl) methacrylates, polymethacrylamide, polynorbornene (including copolymers containing norbornene units), polyolefins (e.g., polyethylene, polypropylene, polytetrafluoroethylene and their copolymers, such as ethylene-α-olefin copolymers), polyoxadiazoles, polyoxymethylene, polyphthalides, polysilazanes, polysiloxanes, polystyrene (including copolymers such as acrylonitrile-butadiene-styrene (ABS) and methyl methacrylate-butadiene-styrene (MBS)), polysulfides, polysulfonamides, polysulfonates, polysulfones, polysulfides, polytriazines, polyureas, polyurethanes, polyvinyl alcohol, polyvinyl esters, polyvinyl ethers, polyvinyl halides, polyvinyl ketones, polyvinyl sulfides, polyvinylidene fluoride, etc., or combinations comprising at least one of the aforementioned thermoplastic polymers. Examples of polyamides may include, but are not limited to, the synthesis of linear polyamides, such as nylon-6,6; nylon-6,9; nylon-6,10; nylon-6,12; nylon-11; nylon-12 and nylon-4,6, preferably nylon 6 and nylon 6,6, or combinations comprising at least one of the foregoing. Polyurethanes that can be used include aliphatic, alicyclic, aromatic and polycyclic polyurethanes, including those mentioned above. Also used is polyacrylic acid (C... 1-6 Alkyl esters and polymethyl methacrylate (C 1-6 Alkyl esters, including polymers such as methyl acrylate, ethyl acrylate, acrylamide, methacrylic acid, methyl methacrylate, n-butyl acrylate, and ethyl acrylate. In embodiments, polyolefins may include one or more of the following materials: polyethylene, polypropylene, polybutene, polymethylpentene (and copolymers thereof), polynorbornene (and copolymers thereof), poly-1-butene, poly(3-methylbutene), poly(4-methylpentene), and copolymers of ethylene with propylene, 1-butene, 1-hexene, 1-octene, 1-decene, 4-methyl-1-pentene, and 1-octadecene.

[0052] In specific embodiments, the 3D printable material (and 3D printing material) comprises one or more of the following materials: polycarbonate (PC), polyethylene (PE), high-density polyethylene (HDPE), polypropylene (PP), polyoxymethylene (POM), polyethylene naphthalate (PEN), styrene-acrylonitrile resin (SAN), polysulfone (PSU), polyphenylene sulfide (PPS), semi-crystalline polyethylene terephthalate (PET), acrylonitrile butadiene styrene (ABS), polymethyl methacrylate (PMMA), polystyrene (PS), and styrene-acrylic acid copolymer (SMMA).

[0053] The term 3D printable material is further elucidated below, but especially refers to a thermoplastic material, optionally comprising additives, in a volume percentage (of the total volume of the thermoplastic material and the additives) of at most about 60%, especially at most about 30 vol.%, such as at most 20 vol.%.

[0054] Hence, in embodiments, the printable material can comprise two phases. The printable material can comprise a phase of a printable polymeric material (especially a thermoplastic material) (see also below), which phase is especially a substantially continuous phase. In this continuous phase of the thermoplastic material, there can be present a polymeric additive, such as one or more of the following additives: antioxidants, heat stabilizers, light stabilizers, ultraviolet light stabilizers, ultraviolet light absorbing additives, near-infrared light absorbing additives, infrared light absorbing additives, plasticizers, lubricants, mold release agents, antistatic agents, antimisting agents, antimicrobial agents, colorants, laser marking additives, surface effect additives, radiation stabilizers, flame retardants, anti-dripping agents. The additives can have useful properties selected from optical properties, electrical properties, thermal properties, and mechanical properties (see also above).

[0055] The printable material in embodiments can comprise a particulate material, i.e. particles embedded in the printable polymeric material, which particles form a substantially discontinuous phase. Especially in applications for lowering the coefficient of thermal expansion, the number of particles in the total mixture is especially not more than 60 vol.% relative to the total volume of the printable material (including the (anisotropically conductive) particles). For optical and surface related effects, the number of particles in the total mixture is equal to or less than 20 vol.%, such as up to 10 vol.% relative to the total volume of the printable material (including the particles). Hence, the 3D printable material especially refers to a substantially continuous phase of a thermoplastic material, in which other materials (such as particles) can be embedded. Similarly, the 3D printable material especially refers to a substantially continuous phase of a thermoplastic material, in which other materials (such as particles) are embedded. The particles can comprise one or more additives as defined above. Hence, in embodiments, the 3D printable material can comprise a particulate additive.

[0056] The printable material is printed on a receiver article. Especially, the receiver article can be or can be comprised by a build platform. The receiver article can also be heated during 3D printing. However, the receiver article can also be cooled during 3D printing.

[0057] The phrase "printing on a receiver article" and similar phrases include, inter alia, printing directly on the receiver article, or printing on a coating on the receiver article, or printing on 3D-printed material that was previously printed on the receiver article. The term "receiver article" can refer to a print platform, print bed, base, support, build plate or build platform, etc. The term "base" can also be used instead of the term "receiver article". The phrase "printing on a receiver article" and similar phrases also include, inter alia, printing on or comprised by a separate base on or by a print platform, print bed, support, build plate or build platform, etc. Hence, the phrase "printing on a base" and similar phrases include, inter alia, printing directly on the base, or printing on a coating on the base or printing on 3D-printed material that was previously printed on the base. In the following, also the term base is used, which can refer to a print platform, print bed, base, support, build plate or build platform, etc. or a separate base on or comprised by them.

[0058] The layer-by-layer deposition of the printable material results in (during the printing phase) a 3D-printed article. The 3D-printed article can show a characteristic rib-like structure (resulting from the deposited filaments). However, a further phase, such as a finishing phase, can be performed after the printing phase. This phase can comprise removing the printed article from the receiver article and / or one or more post-processing actions. The one or more post-processing actions can be performed before removing the printed article from the receiver article, and / or the one or more post-processing actions can be performed after removing the printed article from the receiver article. The post-processing can comprise one or more of, for example, polishing, coating, adding a functional component, cross-linking, etc. The post-processing can comprise smoothing the rib-like structure, which can result in a substantially smooth surface. The post-processing can comprise cross-linking of the thermoplastic material. This can result in a material having less or no thermoplasticity.

[0059] Furthermore, the present invention relates to a software product that can be used to perform the method described herein. Hence, in yet another aspect, the present invention also provides a computer program product that, when running on a computer functionally coupled to or comprised by a fused deposition modeling 3D printer, enables the method as described herein.

[0060] Hence, in one aspect, the present invention (therefore) provides a software product that, when running on a computer, enables the method (one or more embodiments thereof) for producing a 3D article by means of fused deposition modeling as described herein.

[0061] The method described herein provides a 3D-printed article. Hence, in another aspect, the present invention also provides a 3D-printed article that can be obtained with the method described herein. In another aspect, a 3D-printed article that can be obtained with the method described herein is provided.

[0062] In particular, the present application provides a 3D item comprising a 3D printed material, wherein the 3D item can comprise a plurality of layers of the 3D printed material. In embodiments, at least one of these layers comprises a core-shell layer of the 3D printed material. In particular, wherein the 3D printed material comprises: (i) a core comprising a 3D printed core material, and (ii) a shell comprising a 3D printed shell material. In embodiments, the shell can at least partially surround the core. In embodiments, the 3D printed core material has a first porosity pi, and the 3D printed shell material has a second porosity p2; wherein p2 / pi < 0.9, in particular p2 / pi < 0.8, more in particular p2 / pi < 0.6, in embodiments p2 / pi < 0.3, p2 / pi < 0.1, more in particular p2 / pi < 0.05, in particular p2 / pi < 0.01, more in particular p2 / pi < 0.001. Thus, in specific embodiments, the present application provides a 3D item comprising a 3D printed material, wherein the 3D item comprises a plurality of layers of the 3D printed material, wherein at least one of the layers comprises a core-shell layer of the 3D printed material; wherein the 3D printed material comprises (i) a core comprising a 3D printed core material, and (ii) a shell comprising a 3D printed shell material, wherein the shell at least partially surrounds the core, wherein the 3D printed core material has a first porosity pi, wherein the 3D printed shell material has a second porosity p2; wherein p2 / pi < 0.9.

[0063] Thus, in embodiments, the 3D printed shell material has substantially no porosity (i.e. p2 is substantially zero).

[0064] The 3D printed item can comprise a plurality of layers (i.e. stacked layers) on top of each other. The width (thickness) and height of the (individually 3D printed) layers can for example in embodiments be chosen from the range of 100-5000 pm, such as 200-2500 pm, wherein the height is typically smaller than the width. For example, the ratio of height to width can be equal to or smaller than 0.8, such as equal to or smaller than 0.6.

[0065] The layers can be core-shell layers or can consist of a single material. Within the layers, there can also be variations in composition, for example when a core-shell printing process is applied, and during the printing process, which changes from printing a first material (without printing a second material) to printing a second material (without printing the first material).

[0066] At least a portion of the 3D printed item can comprise a coating layer.

[0067] Some specific embodiments with respect to the 3D printed item have been elucidated above when discussing the method. Below, some specific embodiments with respect to the 3D printed item are discussed in more detail.

[0068] In embodiments, the 3D item can have a first porosity pi of the core in the range of 5-60 vol.%, in particular in the range of 5-50 vol.%, more in particular in the range of 5-40 vol.%, such as less than 40 vol.%, more in particular less than 35 vol.%.

[0069] In embodiments, the 3D item can have a density reduction of more than 10%, in particular more than 20%, more in particular more than 30% compared to the theoretical maximum density when pi and p2 are each less than 1 vol.%.

[0070] In specific embodiments, the cross-sectional area of the 3D printed item comprising the at least two (such as at least five) layer axes Ax is larger than or equal to 5 cm 2 , such as equal to or larger than 25 cm 2 .

[0071] In specific embodiments, the 3D printed item comprises at least 5 layers, like at least 8 layers, such as at least 10 layers comprising the porous core as described herein. In yet some other embodiments, layers with the porous core and layers without the porous core can alternate with each other. In yet some embodiments, groups of at least two layers with the porous core and groups of at least two layers without the porous core can alternate with each other.

[0072] The 3D printed item obtained (with the method described herein) can be functional as such. For example, the 3D printed item can be a lens, a collimator, a reflector, etc. The 3D item obtained thereby can (alternatively) be used for decorative or artistic purposes. The 3D printed item can comprise or be provided with functional components. The functional components can in particular be selected from the group consisting of optical components, electrical components, and magnetic components. The term "optical component" in particular refers to components having an optical function (such as lenses, mirrors, light-transmitting elements, optical filters, etc.). The term optical component can also refer to light sources (like LEDs). The term "electrical component" can for example refer to integrated circuits, PCBs, batteries, drivers, but can also refer to light sources (as light sources can be considered both optical components and electrical components), etc. The term magnetic component can for example refer to magnetic connectors, coils, etc. Alternatively or additionally, the functional components can comprise thermal components (e.g. configured to cool or heat electrical components). Thus, the functional components can be configured to generate heat or clear heat, etc.

[0073] As mentioned above, the 3D-printed item can be used for different purposes. Among others, the 3D-printed item can be used for lighting. Hence, in yet another aspect, the present application also provides a lighting device comprising a 3D item as defined herein. In a specific aspect, the present application provides a lighting system comprising (a) a light source configured to provide (visible) light source light and (b) a 3D item as defined herein, wherein the 3D item can be configured as one or more of (i) at least part of an enclosure, (ii) at least part of a wall of a lighting cavity, and (iii) a functional component, wherein the functional component can be selected from the group consisting of an optical component, a support, an electrically insulating component, an electrically conductive component, a thermally insulating component, and a thermally conductive component. Hence, in specific embodiments, the 3D item can be configured as one or more of (i) at least part of a lighting device enclosure, (ii) at least part of a wall of a lighting cavity, and (iii) an optical element. Due to the fact that a relatively smooth surface can be provided, the 3D-printed item can be used as a mirror or a lens, etc. In embodiments, the 3D item can be configured as a cover. The device or system can comprise a plurality of different 3D-printed items having different functions.

[0074] Returning to the 3D-printing process, the 3D-printed item as described herein can be provided using a specific 3D-printer. Hence, in yet another aspect, the present application also provides a fused deposition modeling 3D-printer comprising (a) a print head comprising a printer nozzle, and (b) a 3D-printable material providing device configured to provide a 3D-printable material to the print head, wherein the fused deposition modeling 3D-printer is configured to provide a 3D-printable material as described above.

[0075] The printer nozzle can comprise a single opening. In other embodiments, the printer nozzle can be of core-shell type with two (or more) openings. The term "print head" can also refer to a plurality of (different) print heads; hence, the term "printer nozzle" can also refer to a plurality of (different) printer nozzles.

[0076] The 3D-printable material providing device can provide a filament comprising the 3D-printable material to the print head, or can provide the 3D-printable material itself, wherein the print head generates the filament comprising the 3D-printable material. Hence, in embodiments, the present application provides a fused deposition modeling 3D-printer comprising (a) a print head comprising a printer nozzle, and (b) a filament providing device configured to provide a filament comprising a 3D-printable material to the print head, wherein the fused deposition modeling 3D-printer is configured to provide said 3D-printable material to a substrate, as described above.

[0077] In particular, the 3D printer comprises a controller (or is functionally coupled to a controller) which is configured to execute the method as described herein in a control mode (or "operation mode"). The term "control system" (see above, for example) can also be applied instead of the term "controller".

[0078] The term "control" and similar terms refer, inter alia, to at least determining a behavior of an element or supervising a running of an element. Thus, "control" and similar terms herein can refer, for example, to imposing a behavior on an element (determining a behavior of an element or supervising a running of an element) and the like, such as, for example, measuring, displaying, actuating, opening, displacing, changing a temperature, etc. In addition thereto, the term "control" and similar terms can additionally include monitoring. Thus, the term "control" and similar terms can include imposing a behavior on an element and imposing a behavior on an element and monitoring the element. The control of an element can be done with a control system, which can also be indicated as "controller". The control system and the element can thus be functionally coupled at least temporarily or permanently. The element can comprise the control system. In embodiments, the control system and the element can not be physically coupled. The control can be done via wired and / or wireless control. The term "control system" can also refer to a plurality of different control systems which are functionally coupled, inter alia, and wherein, for example, one control system can be a master control system and one or more other control systems can be slave control systems. The control system can comprise or can be functionally coupled to a user interface.

[0079] The control system can also be configured to receive and execute instructions from a remote control. In embodiments, the control system can be controlled via an App on a device, such as a portable device, like a smartphone or iPhone, a tablet, etc. Thus, the device does not necessarily have to be coupled to the lighting system, but can (temporarily) be functionally coupled to the lighting system.

[0080] Thus, in embodiments, the control system can (also) be configured to be controlled by an App on a remote device. In such embodiments, the control system of the lighting system can be a slave control system or a control in slave mode. For example, the lighting system can be identified with a code, in particular a unique code for the respective lighting system. The control system of the lighting system can be configured to be controlled by an external control system which accesses the lighting system based on knowledge of the (unique) code (input by a user interface with an optical sensor, e.g. a QR code reader). The lighting system can also comprise means for communicating with other systems or devices, such as based on Bluetooth, WIFI, LiFi, ZigBee, BLE or WiMAX, or other wireless technologies.

[0081] A system, apparatus or device can perform an action in a "mode" or "operating mode" or "mode of operation". Similarly, in a method, an action or phase or step can be performed in a "mode" or "operating mode" or "mode of operation" or "operational mode". The term "mode" can also be indicated as "control mode". This does not exclude that the system, apparatus or device can also be adapted to provide another control mode or a plurality of other control modes. Similarly, this can not exclude that one or more other modes can be performed before and / or after the performance of the mode.

[0082] However, in embodiments, a control system can be available which is adapted to provide at least a control mode. The selection of such mode can especially be performed via a user interface if other modes are available, although other options like performing a mode according to a sensor signal or a (time) scheme are also possible. In embodiments, the operating mode can also refer to a system, or apparatus or device which is only capable of operating in a single operating mode (i.e. "on" without further tunability).

[0083] Hence, in embodiments, the control system can be controlled according to one or more of an input signal of a user interface, a sensor signal (of a sensor) and a timer. The term "timer" can refer to a clock and / or a predetermined time scheme.

[0084] The term "3D printer", "FDM printer" or "printer" can be used in short for the term "fused deposition modeling (FDM) 3D printer". A printer nozzle can also be indicated as "nozzle" or sometimes as "extruder nozzle". BRIEF DESCRIPTION OF DRAWINGS

[0085] Embodiments of the application will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

[0086] Figures 1A-1C Some general aspects of one embodiment of a 3D printer and a 3D printing material are schematically depicted;

[0087] Figures 2A-2E Some further aspects of a method of the application are schematically depicted; and

[0088] Figure 3 Applications are schematically depicted.

[0089] The drawings are not necessarily to scale. DETAILED DESCRIPTION

[0090] Figure 1ASome aspects of a 3D printer are schematically depicted. Reference 500 indicates a 3D printer. Reference 530 indicates a functional unit configured for 3D printing, in particular FDM 3D printing; this reference can also indicate a 3D printing stage unit. Here, only a print head for providing 3D printing material is schematically depicted, such as an FDM 3D print head. Reference 501 indicates a print head. The 3D printer of the invention can in particular comprise a plurality of print heads (see below). Reference 502 indicates a printer nozzle. The 3D printer of the invention can in particular comprise a plurality of printer nozzles, although other embodiments are possible as well. Reference 320 indicates a filament of 3D printable material, such as shown above. For the sake of clarity, not all features of the 3D printer are depicted, only those features that are particularly relevant to the invention are depicted (see also further below). Reference 321 indicates an extrudate of (3D printable material 201).

[0091] 3D printer 500 is configured to generate a 3D item 1 by depositing a plurality of layers 322 on a receiver item 550, which in embodiments can be at least temporarily cooled, layer by layer, wherein each layer 322 comprises 3D printable material 201, such as a thermoplastic material having a melting point T m 3D printable material 201 can be deposited on a substrate 1550 (during a printing stage). By deposition, 3D printable material 201 has become 3D printed material 202. 3D printable material 201 that escapes from nozzle 502 is also indicated as extrudate 321. Reference 401 indicates a thermoplastic material.

[0092] 3D printer 500 can be configured to heat filament 320 material upstream of printer nozzle 502. This can for example be done with a device comprising one or more of an extruding and / or heating function. Such a device is indicated with reference 573, and is arranged upstream of printer nozzle 502 (i.e. in time before filament material leaves printer nozzle 502). Print head 501 can (therefore) comprise a liquefier or heater. Reference 201 indicates printable material. When deposited, this material is indicated as (3D) printed material, which is indicated with reference 202.

[0093] Reference 572 indicates a spool or roll with material, in particular in the form of a thread, which can be indicated as filament 320. The 3D printer 500 transforms the filament into an extrudate 321 downstream of the printer nozzle, which becomes a layer 322 on the receiver article or on the already deposited print material. Typically, the diameter of the extrudate 321 downstream of the nozzle 502 is reduced relative to the diameter of the filament 322 upstream of the print head 501. Hence, the printer nozzle is sometimes (also) indicated as extrudate nozzle. Arranging the layers 322 one by one, a 3D article 1 can be formed. Reference 575 indicates a filament providing device, which inter alia comprises a spool or roll, indicated with reference 576, and a drive wheel.

[0094] Reference A indicates a longitudinal axis or filament axis.

[0095] Reference C schematically depicts a control system, for instance a temperature control system configured to control the temperature of the receiver article 550, inter alia. The control system C can comprise a heater capable of heating the receiver article 550 to a temperature of at least 50 °C, but in particular to a range of up to about 350 °C, such as to a temperature of at least 200 °C.

[0096] Alternatively or additionally, in embodiments the receiver plate can also be movable in one or two directions in the x-y plane (horizontal plane). Further, alternatively or additionally, in embodiments the receiver plate can also be rotatable around the (vertical) z-axis. Hence, the control system can move the receiver plate in one or more of the x-direction, the y-direction and the z-direction.

[0097] Alternatively, the printer can have a head which can also be rotated during printing. Such a printer has the advantage that the print material cannot rotate during printing.

[0098] The layers are indicated with reference 322 and have a layer height H and a layer width W.

[0099] Note that the 3D printable material is not necessarily provided to the print head as a filament 320. Further, the filament 320 can also be made in the 3D printer 500 from a sheet of 3D printable material.

[0100] Reference D indicates the diameter of the nozzle through which the 3D printable material 201 is forced.

[0101] Figure 1BThe printing of the constructed 3D item 1 is schematically depicted in more detail in 3D. Here, in this schematic drawing, the ends of the filaments 321 in the individual planes are not interconnected, although in embodiments this can actually be the case. Reference H indicates the height of the layer. The layers are indicated with reference 322. Here, the layers have a substantially circular cross-section. However, in general, they can be flat, such as having an outer shape similar to a flat elliptical tube or flat elliptical conduit (i.e. having a circular rod with a diameter compressed into a height smaller than the width, wherein the side (defining the width) is still circular).

[0102] Thus, Figures 1A-1B Some aspects of a fused deposition modeling 3D printer 500 are schematically depicted, including: (a) a first print head 501 comprising a printer nozzle 502; (b) a filament providing device 575 configured to provide a filament 321 comprising a 3D printable material 201 to the first print head 501; and optionally (c) a receiver item 550. In Figures 1A-1B In general, the first or second printable material or the first or second print material is indicated with the general designations printable material 201 and print material 202, respectively. Directly downstream of the nozzle 502, the filament 321 with the 3D printable material 201 becomes a layer 322 with the 3D print material 202 when deposited.

[0103] Figure 1C A stack of 3D printed layers 322 is schematically depicted, each stack having a layer height H and a layer width W. Note that in embodiments, the layer width and / or the layer height can be different for two or more of the layers 322. Figure 1C Reference 252 in indicates an item surface of the 3D item (in Figure 1C is schematically depicted).

[0104] Reference is made to Figures 1A-1C The deposited filament of 3D printable material results in a layer having a height H (and a width W). By depositing the layers 322 one by one, the 3D item 1 is generated. Figure 1C A single-walled 3D item 1 is very schematically depicted.

[0105] Figures 2A-2E Some further aspects of the method of the invention are schematically depicted. Figures 2A-2B Some embodiments of the (core-shell) filament 320 that can be used in the method are depicted. The filament 320 can be used in the printer 500, for example, as Figures 1A-1B is shown, the printer 500 has a nozzle 502 with a single opening. The geometry of the filament, in particular the width W1F of the core, the height H1F of the core and the width (or thickness) W2F of the shell are shown. In Figure 2BIn embodiments, the shell material 341 comprising the shell polymeric material 345 completely surrounds the core material 331 (comprising the core polymeric material 335) (W2F is non-zero at all locations along the periphery of the filament 320).

[0106] In Figures 2A-2B In the depicted embodiment, the filament 320 comprises (i) a core material 331 comprising a printable core material 1351, wherein the printable core material 1351 comprises a pore-forming material 210; and (ii) a shell material 341 comprising a printable shell material 1361.

[0107] In Figure 2A In embodiments, the shell material 341 only partially surrounds the core material 331. The shell material 341 does not surround the core material 331 at two locations indicated by the arrows; at these locations W2F is zero (0 pm). As such, the shell material 341 of the filament 320 covers (surrounds) the core material 331 of the filament 320 at two consecutive portions arranged at the surface of the filament 320, wherein W2F is non-zero.

[0108] In the 3D printing phase, the filament 320 comprising Figure 2B The filament 320 comprising Figure 2D the depicted 3D item 1. In the 3D printing phase, the filament 320 comprising Figure 2A The filament 320 comprising Figure 2E the depicted 3D item 1 or in embodiments a stack of core-shell layers 1332, wherein W2 is zero at some locations between two adjacent layers 1322 and non-zero at other locations (between adjacent layers).

[0109] In addition to or as an alternative to using core-shell filaments, a core-shell nozzle 502 as schematically illustrated in Fig. 2c can be used. The filament 320 comprising the core printable material 1351 and the shell printable material 1361 enters a print head 501 in a core nozzle (no reference number) and a shell nozzle 30, respectively. The core printable material 1351 can comprise a pore-forming material 210. During the pore-forming phase, the pore-forming material is heated and can form pores 412. After extrusion, a core-shell layer 1322 is deposited, which comprises a core 330 comprising a core material 331 comprising a core printable material 1352; and a shell 340 comprising a shell material 341 comprising a shell printable material 1362.

[0110] Figures 2D-2EA stack of 3D-printed core-shell layers 1322 is schematically depicted. The layers comprise core-shell layers 1322 of 3D-printed material 202 and comprise a core 330 and a shell 340. The core 330 comprises a core material 331 comprising a first component. The shell 340 comprises a shell material 341 comprising a second component that is different from the first component, e.g. in physical, chemical and / or optical properties. In embodiments, the core print material 1352 comprises a hole 412. Further, a core height of the core 330 is indicated with reference H1 and a core width is indicated with reference W1. The shell 340 has a shell width W2. The shell width W2 can also be referred to herein as a thickness W2 of the shell 340. Figure 2D An embodiment is depicted in which (in each core-shell layer 1322) the shell 340 substantially completely surrounds the core 330. In Figure 2E In an embodiment, the shell 340 partially surrounds the core 330 in each core-shell layer 1322.

[0111] Further, as Figures 2D-2E is shown, the core width W1 and the shell width W2 can be determined substantially perpendicular to the stack height. Further, the core height H1 can be determined substantially parallel to the stack height.

[0112] Figure 2E An embodiment is further illustrated that comprises a plurality of core-shell layers 1322 on top of each other, in which the shell width W2 between two adjacent cores 330 is 0 pm, and in which the shell width W2 at at least one side of the core 330 is non-zero. In embodiments, the shell width W2 at both sides of the core 330 is non-zero. Further, two surfaces 252 of the article 1 are schematically indicated. Figures 2D-2E A 3D article 1 is very schematically depicted having an article wall comprising two surfaces. Figure 2E It is also depicted that both surfaces of the wall comprise shell material 341 without core material 331. In further embodiments, one or a portion of the surfaces of the wall comprises shell material 341. In the former embodiment (in which one surface comprises shell material), in particular the shell material 341 can be arranged at only one side of the core material 331. In Figure 2E In an embodiment, the shell material 341 is arranged at both sides of the core material 331.

[0113] Figures 2D-2E An embodiment is further illustrated in which in the core-shell layers 1322, the shell material 341 completely surrounds the core material 331 (Fig. 2d) between the core-shell layers 1322, the shell material 341 completely surrounds the core material 331 (Fig. 2d) in the 3D article 1. Figure 2E

[0114] Reference is made to Figures 2D-2E ​The term "shell width" can in particular refer to the maximum shell width. The term "core height" can in particular also refer to the maximum core height. The term "core width" can in particular also refer to the maximum core width. In particular, the maximum shell width is the shell width in the same plane as the maximum core width.

[0115] In embodiments, the shell material 341 can cover the core material 331, in particular hiding the core material 331 and / or protecting the core material 331.

[0116] Figure 3 One embodiment of a lamp or luminaire indicated with reference number 2 is schematically depicted, which comprises a light source 10 for generating light 11. The lamp can comprise an outer shell or cover or another element, which can comprise or be a 3D printed article 1. Here, the half sphere (in cross-sectional view) is schematically indicative of the outer shell or cover. The lamp or luminaire can be or can comprise the lighting device 1000 (which comprises the light source 10). Hence, in specific embodiments, the lighting device 1000 comprises the 3D article 1. The 3D article 1 can be configured as one or more of (i) at least part of a lighting device outer shell, (ii) at least part of a wall of a lighting cavity, and (iii) an optical element. Hence, in embodiments, the 3D article can be reflective for the light source light 11 and / or transmissive for the light source light 11. Here, the 3D article can for example be an outer shell or cover.

[0117] The term "a plurality of" refers to two or more.

[0118] The terms "substantially" or "essentially" and similar terms will be understood by the skilled person herein. The terms "substantially" or "essentially" can also include embodiments with "entirely", "completely", "all" and the like. Hence, in embodiments, the adjective "substantially" or "essentially" can also be removed. Where applicable, the term "substantially" or the term "essentially" can also relate to 90% or more, such as 95% or more, in particular 99% or more, even more in particular 99.5% or more, including 100%.

[0119] The term "comprising" also includes embodiments where the term "comprising" is interpreted as "consisting of".

[0120] The term "and / or" relates in particular to one or more of the items preceding and following "and / or". For example, the phrase "item 1 and / or item 2" and similar phrases can relate to one or more of item 1 and item 2. The term "comprising" can in one embodiment refer to "consisting of", but can in another embodiment also refer to "at least containing the defined substance and optionally one or more further substances".

[0121] Furthermore, the terms first, second, third, etc. have been used, in the description and in the claims, to describe various elements, but the elements should not be limited to these descriptions and / or terms. It will be understood that the terms so used are also interchangeable under appropriate circumstances. The embodiments of the application described herein are capable of operating in different sequences than described or illustrated herein.

[0122] These devices, apparatuses, or systems can be described herein, inter alia, during operation. As will be obvious to those skilled in the art, the application is not limited to methods of operation, or devices, apparatuses, or systems in operation.

[0123] It should be noted that the above-mentioned embodiments illustrate rather than limit the application, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims.

[0124] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

[0125] The use of the verb "comprise" and its conjugations does not exclude the presence of elements other than those stated in the claims. In the entire description and claims, the word "comprising" and its conjugations should not be interpreted as being restricted to the meaning of "including only that which follows", but rather, should be interpreted as meaning "including at least that which follows".

[0126] The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0127] The application can be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In a device claim enumerating several means, those means can be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0128] The application also provides a control system, which can control a device, apparatus, or system, or which can carry out a method or process as described herein. Furthermore, the application also provides a computer program product, which, when running on a computer functionally coupled to or comprised by a device, apparatus, or system, controls one or more controllable elements of such device, apparatus, or system.

[0129] The application also applies to a device, apparatus, or system comprising one or more of the characterising features described in the description and / or shown in the drawings. The application also relates to a method or process comprising one or more of the characterising features described in the description and / or shown in the drawings.

[0130] Various aspects discussed in this patent can be combined to facilitate providing additional advantages. Further, those skilled in the art will appreciate that embodiments can be combined and more than two embodiments can be combined. Moreover, some features can form the basis of one or more divisional applications.

[0131] It goes without saying that one or more of the first (printable or printed) material and the second (printable or printed) material can comprise a T g or T m Fillers (such as glass and fibers) that have no (not necessarily no) influence.

Claims

1. A method for producing 3D articles (1) by means of fused deposition modeling, the method comprising: The 3D printing stage includes: layer-by-layer deposition of a 3D printable material (201), wherein the 3D printable material (201) comprises a 3D printable core material (1351) and a 3D printable shell material (1361) to provide the 3D article (1) comprising a core-shell layer (1322) of the 3D printable material (202), wherein the 3D printable material (202) comprises a core (330) and a shell (340), the core (330) comprising the 3D printable core material (1352), the shell (340) comprising the 3D printable shell material (1362), wherein the shell (340) at least partially surrounds the core (330), wherein the 3D printable core material (1351) comprises a pore-forming material (210) having a first concentration c1, and wherein the 3D printable shell material (1361) comprises the pore-forming material (210) having a second concentration c2, wherein ;as well as The pore-forming stage includes heating one or more of the following materials: (i) the 3D printable material (201) and (ii) the 3D printing material (202).

2. The method according to claim 1, wherein And in terms of weight percentage, %, and in terms of weight percentage, %.

3. The method according to any one of claims 1 and 2, wherein the shell (340) of the core-shell layer (1322) of the 3D article (1) has a shell width (W2), wherein the core-shell layer (1322) has a layer width (W); wherein 0.01 ≤ W2 / W ≤ 0.3, and wherein the first porosity p1 of the core (330) of the core-shell layer (1322) is in the range of 5% to 40% by volume.

4. The method according to any one of claims 1 and 2, wherein the pore-forming material (210) has a boiling temperature, and wherein the method comprises 3D printing the 3D printable material (201) at a nozzle temperature higher than the boiling temperature.

5. The method according to any one of claims 1 and 2, wherein the pore-forming material (210), the first concentration c1, the second concentration c2, and the 3D printing conditions are selected such that the density of the core-shell layer (1322) is reduced by more than 10% compared to the theoretical maximum density obtained when no pore-forming material (210) is incorporated into the 3D printable material (201).

6. The method according to any one of claims 1 and 2, wherein the core (330) and the shell (340) are the same thermoplastic material.

7. The method according to any one of claims 1 and 2, wherein the pore-forming material (210) comprises water, and wherein the pore-forming stage comprises applying one or more of the following: (i) microwave radiation and (ii) ultrasound.

8. The method according to any one of claims 1 and 2, wherein the pore-forming material (210) in the 3D printable core material (1351) and the pore-forming material (210) in the 3D printable shell material (1361) are one of the following pore-forming materials: (i) the same pore-forming material (210) or the same pore-forming material (210) at the same ratio, (ii) the same pore-forming material (210) at a different ratio, or (iii) a different pore-forming material (210); wherein the pore-forming material (210) in the 3D printable core material (1351) has a boiling point above room temperature.

9. A filament (320) for producing a 3D article (1) by means of fused deposition modeling, said filament (320) comprising: (i) a core (330) comprising a 3D-printable core material (1351), wherein the 3D-printable core material (1351) comprises a pore-forming material (210) at a first concentration c1; and (ii) a shell (340) comprising a 3D-printable shell material (1361), wherein the 3D-printable shell material (1361) comprises the pore-forming material (210) at a second concentration c2; wherein And in terms of weight percentage, %; wherein the shell (340) at least partially surrounds the core (330).

10. The filament according to claim 9, wherein And in terms of weight percentage, %.

11. A 3D article (1) comprising 3D printing material (202), wherein the 3D article (1) comprises a plurality of layers (322) of the 3D printing material (202), wherein at least one of the layers (322) comprises a core-shell layer (1322) of the 3D printing material (202); wherein the 3D printing material (202) comprises: (i) a core (330) comprising a 3D printed core material (1352), and (ii) a shell (340) comprising a 3D printed shell material (1362), wherein the shell (340) at least partially surrounds the core (330), wherein the 3D printed core material (1352) has a first porosity p1, and wherein the 3D printed shell material (1362) has a second porosity p2; wherein p2 / pl < 0.

9.

12. The 3D article (1) according to claim 11, wherein the first porosity p1 of the core (330) is in the range of 5% to 40% by volume, and wherein .

13. The 3D article (1) according to any one of claims 11 and 12, wherein when p1 and p2 are each less than 1% of the volume percentage, the 3D article (1) has a density reduction of more than 10% compared to the theoretical maximum density.

14. The 3D article (1) according to any one of claims 11 and 12, wherein the shell (340) has a shell width (W2), and wherein the core-shell layer (1322) has a layer width (W); wherein .

15. An illumination device (1000) comprising a 3D article (1) according to any one of claims 11 and 12, wherein the 3D article (1) is configured as one or more of: (i) at least a portion of an illumination device housing, (ii) at least a portion of a wall of an illumination cavity, and (iii) an optical element.

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