Method of applying 2d patterns to 3D objects

Abstract

The present invention relates to a method of manufacturing a 3D article (1) by fused deposition modeling, the method comprising the steps of: a) depositing a first 3D printable material (4) and a second 3D printable material (5) in layers to provide a 3D article (1) comprising a stack of layers (2) having an exposed surface (3), where the first 3D printable material (4) has a first polarity and a first porosity; wherein the second 3D printable material (5) has a second polarity and a second porosity; the first polarity is different from the second polarity and / or the first porosity is different from the second porosity; wherein the first 3D printable material (4) forms a first surface portion (4 ') of the exposed surface (3) of the layer stack (2) and the second 3D printable material (5) forms a second surface portion (5') of the exposed surface (3) of the layer stack (2), and wherein the method further comprises the following steps: b) applying a coating (7) on the second surface portion (5 ') of the exposed surface (3) of the layer stack (2).

Description

Technical Field

[0001] The present invention relates to a method for applying a 2D pattern to a 3D printed object. Furthermore, the present invention relates to a 3D printable material for use in the method. The present invention also relates to a 3D printed object obtainable by the method. Furthermore, the present invention relates to a lighting device comprising such a 3D printed object. Background Art

[0002] Digital manufacturing will increasingly change the nature of global manufacturing over the next 10 to 20 years. One aspect of digital fabrication is 3D printing. Currently, many different technologies have been developed to produce a variety of 3D printed objects using a variety of materials such as ceramics, metals, and polymers.

[0003] The most widely used additive manufacturing technology is the process known as fused deposition modeling (FDM). Fused deposition modeling (FDM) is an additive manufacturing technology commonly used for modeling, prototyping and production applications. FDM works on an "additive" principle by laying down material in layers; a plastic filament or metal wire is unwound from a coil and provides the material to create a part. For example, in the case of thermoplastics, the filament may be melted and extruded before being laid down. Generally speaking, FDM printers use thermoplastic filaments, which are heated to their melting point and then extruded layer by layer, or indeed filament by filament, to create a three-dimensional object. FDM printers are relatively fast, low-cost and can be used to print complex 3D objects. Such printers are used to print a variety of shapes using a variety of polymers. The technology has also been further developed for the production of LED lamps and lighting solutions.

[0004] Sometimes, it may be desirable to provide a 2D printed pattern on a 3D printed object for decorative or informational purposes.

[0005] However, many plastic materials used as FDM 3D printable materials have chemically inert and non-porous surfaces with low surface tension, making them difficult to bond with printing inks, coatings and adhesives.

[0006] Therefore, there is a need to provide a method for applying 2D patterns to 3D objects in an efficient manner. Summary of the invention

[0007] In view of the above, the present invention provides such a method. The method for producing 3D objects by fused deposition modeling (FDM) of the present invention comprises the following steps:

[0008] a) depositing in layers a first 3D printable material and a second 3D printable material to provide a 3D object comprising a layer stack having an exposed surface,

[0009] wherein the first 3D printable material has a first polarity and a first porosity;

[0010] wherein the second 3D printable material has a second polarity and a second porosity;

[0011] The first polarity is different from the second polarity and / or the first porosity is different from the second porosity;

[0012] wherein the first 3D printable material forms a first surface portion of the exposed surface of the layer stack, and the second 3D printable material forms a second surface portion of the exposed surface of the layer stack;

[0013] Wherein the method also comprises the following steps:

[0014] b) Applying a coating on a second surface portion of the exposed surface of the layer stack.

[0015] The term "3D printable material" refers to the material to be deposited or to be printed, and the term "3D printing material" refers to the material obtained after deposition. These materials can be substantially the same, because the 3D printable material can particularly refer to the material in the print head or extruder at an elevated temperature, and the 3D printing material refers to the same material, but at a stage after deposition. The 3D printing material can be printed as a filament and deposited in the form of a filament. The 3D printable material can be provided as a filament, or it can be formed into a filament. Therefore, regardless of the starting material used, the filament containing the 3D printable material is provided by the print head and 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 printing material". In fact, the extrudate contains the 3D printable material because the material has not yet been deposited. After the 3D printable material or extrudate is deposited, the material is therefore indicated as a 3D printing material. Generally, the 3D printable material, the extrudate and the 3D printing material are the same material as the material upstream of the print head, downstream of the print head, and are substantially the same material when deposited.

[0016] Herein, the term "3D printable material" may also be indicated as "printable material". The term "polymeric material" may refer to a mixture of different polymers, but in embodiments may also refer to a substantially single polymer type with different polymer chain lengths. Thus, the term "polymeric material" or "polymer" may refer to a single type of polymer, but may also refer to a plurality of different polymers. The term "printable material" may refer to a single type of printable material, but may also refer to a plurality of different printable materials. The term "printing material" may refer to a single type of printing material, but may also refer to a plurality of different printing materials.

[0017] The first 3D printable material may include a first thermoplastic polymer, and the second 3D printable material may include a second thermoplastic polymer that is identical to the first thermoplastic polymer. This embodiment provides the advantage of simplified and therefore cost-effective manufacturing, wherein both the first and second 3D printable materials include the same polymer matrix, and wherein the second 3D printable material may be modified such that the second polarity and / or the second porosity of the second 3D printable material is different from the first polarity and / or the first porosity of the first 3D printable material. In particular, the first and / or the second thermoplastic polymer may be polyethylene (PE) or polypropylene (PP).

[0018] Alternatively, the second thermoplastic polymer may be different from the first thermoplastic polymer. In this embodiment, the second polarity and / or the second porosity of the second thermoplastic polymer is different from the first polarity and / or the first porosity of the first thermoplastic polymer.

[0019] The first thermoplastic material may be a single material or a combination of two or more materials. Similarly, the second thermoplastic material may be a single material or a combination of two or more materials. If a combination of at least two materials is used, all materials constituting the second thermoplastic material should have a polarity and / or porosity different from that of the first thermoplastic material.

[0020] The 3D printable material may include an additive, wherein the volume percentage of the additive is at most about 60 volume %, in particular at most about 30 volume %, such as at most 20 volume %, relative to the total volume of the thermoplastic material and the additive.

[0021] The at least one additive may be selected from 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, antifogging agents, antimicrobial agents, colorants, laser marking additives, surface effect additives, radiation stabilizers, flame retardants, and anti-drip agents. The additive may have useful properties selected from optical properties, electrical properties, thermal properties, and mechanical properties.

[0022] Typically, the first thermoplastic material and the second thermoplastic material have a glass transition temperature Tg and / or a melting temperature Tm. The glass transition temperature Tg and / or the melting temperature Tm of the first thermoplastic material may be the same or different from the glass transition temperature Tg and / or the melting temperature Tm of the second thermoplastic material. The 3D printable material will be heated to at least the glass transition temperature, typically at least the melting temperature, by the 3D printer before leaving the nozzle. Therefore, the print head action may include heating the 3D printable material to above the glass transition temperature or above the melting temperature. It should be noted that melting occurs when polymer chains fall off from their crystal structure and become a disordered liquid, while the glass transition is a transition that occurs on an amorphous polymer (that is, a polymer whose chains are not arranged in an ordered crystal, but are dispersed around in any way, even if they are in a solid state). The polymer may be amorphous, essentially having a glass transition temperature rather than a melting temperature, or may be (semi) crystalline, typically having a glass transition temperature and a melting temperature, the latter typically being higher than the former. The glass transition temperature and the melting point may be determined, for example, by differential scanning calorimetry.

[0023] As will be apparent from the above, the purpose of introducing the second 3D printable material is to provide a surface portion, ie the second surface portion, having an enhanced affinity for a coating to be applied to the 3D article.

[0024] The 3D object manufactured according to the method of the present invention may be a core-shell object, wherein the core may be formed of one of a first 3D printable material and a second 3D printable material, and wherein the shell is formed of the other of the first 3D printable material and the second 3D printable material. In such an embodiment, the shell is not printed in a desired area, so that the core forms a first surface portion of the exposed surface.

[0025] The coating may comprise or may be an ink and / or an adhesive.Thus, the method of the present invention provides for an improved transfer of a coating (eg a 2D image) onto the surface of a 3D object.

[0026] The ink and / or adhesive may contain a colorant, such as a dye and / or pigment. The dye and / or pigment may have a color or reflectivity that is different from the color or reflectivity of the first surface portion. For example, the difference in reflectivity may be at least 30%, preferably at least 40%, and more preferably at least 50%.

[0027] In certain embodiments, the coating may not be applied on the first surface portion of the exposed surface of the layer stack.

[0028] The first polarity may correspond to or be hydrophilicity, and the second polarity may correspond to or be hydrophobicity. Alternatively, the first polarity may correspond to or be hydrophobicity, and the second polarity may correspond to or be hydrophilicity.

[0029] The first polarity may be a (relatively) high polarity, and the second polarity may be a (relatively) low polarity. A material with a low polarity may be referred to as a non-polar material. Alternatively, the first polarity may be a (relatively) low polarity, such as non-polar, and the second polarity may be a (relatively) high polarity. Typically, the second polarity is greater than the first polarity.

[0030] The coating may have a polarity that is the same as or comparable to the second polarity. If the second polarity is (relatively) high, the polarity of the coating may also be (relatively) high. For example, if the second polarity corresponds to or is hydrophilic, the coating may also be hydrophilic. If the second polarity is (relatively) low, the polarity of the coating may also be relatively low. For example, if the second polarity corresponds to or is hydrophobic, the coating may also be hydrophobic.

[0031] The second porosity may be greater than the first porosity. To this end, the second 3D printable material may include a modified thermoplastic material, such as polymethyl methacrylate (PMMA). The modified thermoplastic material may be in the form of particles dispersed in a polymer matrix. This embodiment has the advantage of improving the adhesion of the coating to the second surface portion compared to the first surface portion. Porosity (or void ratio) is a measure of the void (i.e., "empty") space in the material, and is the ratio of the void volume to the total volume, between 0 and 1, or a percentage between 0% and 100%. In particular, the total amount of "accessible voids", i.e., the void space accessible from the surface, can be used as a definition. The difference between the first porosity and the second porosity may be at least 30%, preferably at least 40%, and more preferably at least 50%.

[0032] The second surface portion of the exposed surface of the layer stack can form a pattern. The pattern can match the pattern to be printed on the 3D object, such as a picture, pictogram or text.

[0033] Alternatively or additionally, the second 3D printable material may include filler particles. The filler particles may be selected from the group consisting of wood particles, paper particles, metal particles, ceramic particles, glass particles, and combinations thereof. In particular, the filler particles may be porous glass particles. In addition, the filler particles may be reflective particles, such as reflective flakes with a high aspect ratio. This embodiment provides a second surface portion with a high specular reflectivity. The concentration of filler particles in the second 3D printable material may be less than 0.1 wt %.

[0034] Each filler particle may have a minimum bounding box having a length Lp, a width Wp and a height Hp. The term "minimum bounding box" is understood to be a box with a minimum volume into which the particle fits. In particular, the ratio between Lp and Hp may be greater than 5, i.e. Lp / Hp>5. In such an embodiment, the filler particles are in the form of flakes and needles. Furthermore, the ratio between Wp and Hp may be greater than 5, i.e. Wp / Hp>5. In such an embodiment, the filler particles are in the form of needles, thereby increasing the coating affinity of the second surface portion.

[0035] The first surface portion of the 3D article may have visual and / or tactile properties that are different from the properties of the second surface portion of the 3D article. In particular, the visual and / or tactile properties of the second surface portion of the 3D article are different from the visual and / or tactile properties of the first surface portion of the 3D article before step b) (i.e., before applying the coating). Such an embodiment provides the advantage of indicating where the coating will be located so that a user can verify the correctness of the pattern to be provided on the 3D article before applying the coating.

[0036] The method according to the present invention may further comprise step c) applying a protective layer on the second surface portion of the exposed surface of the layer stack of the 3D article. The protective layer may be clear and transparent. The protective layer may be used to fix the coating on the second surface portion. The thickness of the protective layer may preferably be lower than 0.5Lp of the filler particles. If present, step c) occurs after step b) so that the protective layer is applied after the coating, thereby protecting the printed image.

[0037] It should be noted that steps a), b) and c) are performed in a sequential manner, i.e. step a) is performed before step b), and step b) is performed before step c). The method of the present invention may include further steps, such as cooling, curing, washing, drying, etc. These additional steps may be performed between steps a), b) and / or c).

[0038] It is also conceivable that steps a) and b) partially overlap. In other words, when step b) starts, step a) may still be in progress.

[0039] The first surface portion of the exposed surface of the layer stack may have a first area R1, and the second surface portion of the exposed surface of the layer stack may have a second area R2, wherein the first area may be greater than the second area. In particular, the ratio between the second area R2 and the first area R1 may be 0.01 to 0.5, preferably 0.03 to 0.3, and more preferably 0.05 to 0.1.

[0040] The 3D printable material is printed on a recipient object. In particular, the recipient object may be a building platform, or may also be comprised by a building platform. During the 3D printing process, the recipient object may also be heated. However, during the 3D printing process, the recipient object may also be cooled.

[0041] The phrase "printing on a recipient item" and similar phrases particularly include printing directly on the recipient item, or printing on a coating on the recipient item, or printing on a 3D printing material previously printed on the recipient item. The term "receiver item" may refer to a printing platform, a print bed, a substrate, a support, a building panel, or a building platform. The term "substrate" may also be used instead of the term "receiver item". Therefore, the phrase "printing on a substrate" and similar phrases particularly include printing directly on a substrate, or printing on a coating on a substrate, or printing on a 3D printing material previously printed on a substrate.

[0042] The printable material is deposited layer by layer, by which a 3D printed object is generated in a printing phase. The 3D printed object may display a characteristic ribbed structure originating from the deposited filaments. However, it is also possible to perform another phase after the printing phase, such as a finishing phase. This phase may include removing the printed object from the recipient object and / or one or more post-processing actions. One or more post-processing actions may be performed before removing the printed object from the recipient object, and / or one or more post-processing actions may be performed after removing the printed object from the recipient object. Post-processing may include, for example, one or more of polishing, coating, adding functional ingredients, cross-linking, etc. Post-processing may include smoothing the ribbed structure, which may result in a substantially smooth surface. Post-processing may include cross-linking of the thermoplastic material. This may result in a reduction or disappearance of the thermoplastic properties of the material.

[0043] The present invention also relates to a 3D printable material for the above method. The 3D printable material according to the present invention comprises a first 3D printable material having a first polarity and a first porosity; and a second 3D printable material having a second polarity and a second porosity; the first polarity is different from the second polarity and / or the first porosity is different from the second porosity. The features of the first 3D printable material and the second 3D printable material are similar to the above description.

[0044] Furthermore, the present invention relates to a 3D article comprising a layer stack having an exposed surface, wherein the layer stack comprises a first 3D printed material having a first polarity and a first porosity, and a second 3D printed material having a second polarity and a second porosity; the first polarity being different from the second polarity and / or the first porosity being different from the second porosity. The first 3D printed material forms a first surface portion of the exposed surface of the layer stack, and the second 3D printed material forms a second surface portion of the exposed surface of the layer stack.

[0045] In order to have good adhesion between the polar layer and the non-polar layer, core-shell type printing can be used. For example, a polar polymer can be used in the core and a non-polar polymer can be used in the shell. Therefore, in the area where only the core is printed, the core becomes the exposed surface and has polarity. In the area where the core and shell are printed, the shell becomes the exposed surface and the surface is non-polar.

[0046] Similar to above, the second surface portion of the exposed surface of the layer stack may be patterned.

[0047] In particular, the second surface portion of the exposed surface of the layer stack may comprise a coating, such as ink.The 3D object of the present invention may be manufactured by the method described above.

[0048] A 3D printed object may include multiple layers stacked on top of each other, i.e. a stack of layers. The width W of an individual 3D printed layer is L and height H L For example, in an embodiment, it can be selected from the range of 100-5000 μm, such as 200-2500 μm, wherein the height is usually smaller than the width. For example, the ratio of height to width can be equal to or less than 0.8, such as equal to or less than 0.6. It should be noted that the layer width W of each layer L and / or floor height H L Can be combined with other layers in terms of layer width WL and / or layer height H L The 3D printed object may comprise at least 5 layers, such as at least 8 layers, such as at least 10 layers.

[0049] Finally, the present invention provides a lighting device comprising a 3D object as described above. The 3D object can be configured as one or more of the following: (i) at least a portion of a housing of the lighting device, (ii) at least a portion of a wall of a lighting chamber, and (iii) an optical element. The optical element can be a lens, a collimator, or a reflector. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings, in which corresponding reference characters indicate corresponding parts, and in which:

[0051] Figure 1a A portion of a 3D object according to the invention (a filament according to the invention) is depicted;

[0052] Figure 1b Shows Figure 1a A portion of a 3D object with a 2D image.

[0053] All the figures are schematic, not necessarily to scale, and generally show only parts which are necessary in order to elucidate embodiments of the invention, wherein other parts may be omitted or merely suggested. DETAILED DESCRIPTION

[0054] The present invention will now be described below with reference to the accompanying drawings, in which exemplary embodiments of the present invention are shown. However, the present invention may be implemented in many different forms and should not be construed as limited to the embodiments of the present invention set forth herein; rather, these embodiments of the present invention are provided by way of example so that this disclosure will convey the scope of the present invention to those skilled in the art. In the accompanying drawings, the same reference numerals represent the same or similar components having the same or similar functions, unless otherwise specifically stated.

[0055] Figure 1a A 3D article 1 comprising a layer stack 2 having an exposed surface 3 is shown. Figure 1a The 3D printed object 1 depicted in FIG. 1 includes 8 layers.

[0056] The layer stack 2 includes a first 3D printed material 4 having a first polarity and a first porosity and a second 3D printed material 5 having a second polarity and a second porosity; the first polarity is different from the second polarity and / or the first porosity is different from the second porosity. The first 3D printed material 4 forms a first surface portion 4' of the exposed surface 3 of the layer stack 2, and the second 3D printed material 5 forms a second surface portion 5' of the exposed surface 3 of the layer stack 2.

[0057] As mentioned above, the second surface portion 5 ′ of the exposed surface 3 of the layer stack 2 may be patterned.

[0058] The second 3D printing material 5 includes filler particles 6. The filler particles 6 may be selected from the group consisting of wood particles, paper particles, metal particles, ceramic particles, glass particles, and combinations thereof. In particular, the filler particles may be porous glass particles. In addition, the filler particles 6 may be reflective particles, such as reflective flakes with a high aspect ratio. This embodiment provides a second surface portion 5' with a high specular reflectivity. The concentration of the filler particles 6 in the second 3D printing material 5 may be less than 0.1 wt%.

[0059] Each filler particle 6 may have a minimum bounding box having a length Lp, a width Wp and a height Hp. The term "minimum bounding box" is understood to be a box with a minimum volume into which the particle fits. In particular, the ratio between Lp and Hp may be greater than 5, i.e. Lp / Hp>5. In such an embodiment, the filler particles 6 are in the form of flakes and needles. Furthermore, the ratio between Wp and Hp may be greater than 5, i.e. Wp / Hp>5. In such an embodiment, the filler particles 6 are in the form of needles, thereby increasing the coating affinity of the second surface portion 5'.

[0060] from Figure 1aAs can be seen in the figure, the first surface portion 4' of the 3D object 1 has visual and / or tactile properties that are different from the properties of the second surface portion 5' of the 3D object 1. In particular, the visual and / or tactile properties of the second surface portion 5' of the 3D object 1 are different from the visual and / or tactile properties of the first surface portion 4' of the 3D object 1 before step b), i.e. before applying the coating 7. Such an embodiment provides the advantage of indicating where the coating 7 will be located, so that the user can verify the correctness of the pattern to be provided on the 3D object 1 before applying the coating 7.

[0061] from Figure 1b As can be seen in FIG. 2 , the second surface portion 5 ′ of the exposed surface 3 of the layer stack 2 comprises a coating 7 , for example ink.

[0062] The first surface portion 4' of the exposed surface 3 of the layer stack 2 may have a first area R1, and the second surface portion 5' of the exposed surface 3 of the layer stack 2 may have a second area R2, wherein the first area may be greater than the second area. In particular, the ratio between the second area R2 and the first area R1 may be 0.01 to 0.5, preferably 0.03 to 0.3, and more preferably 0.05 to 0.1.

[0063] Although the present invention has been described with reference to various embodiments, those skilled in the art will recognize that changes may be made without departing from the scope of the invention. The specific embodiments are intended to be regarded as illustrative, and the appended claims (including all equivalents) are intended to define the scope of the invention. Although the present invention has been described in the drawings and the foregoing description, the description should be regarded as illustrative or exemplary, not restrictive; the invention is not limited to the disclosed embodiments. By studying the drawings, the disclosure and the appended claims, those skilled in the art can understand and implement other variations of the disclosed embodiments when practicing the claimed invention. In the appended claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude the plural. The mere fact that certain measures are listed in mutually different dependent claims does not mean that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be interpreted as limiting the scope.

Claims

1. A method for manufacturing a 3D object (1) by fused deposition modeling, the method comprising the following steps: a) depositing a first 3D printable material (4) and a second 3D printable material (5) in layers to provide said 3D object (1) comprising a layer stack (2) having an exposed surface (3), wherein the first 3D printable material (4) has a first polarity; wherein the second 3D printable material (5) has a second polarity; One of the first polarity and the second polarity corresponds to or is hydrophilic, and the other of the first polarity and the second polarity corresponds to or is hydrophobic; wherein the first 3D printable material (4) forms a first surface portion (4') of the exposed surface (3) of the layer stack (2), and the second 3D printable material (5) forms a second surface portion (5') of the exposed surface (3) of the layer stack (2); Wherein the method further comprises the following steps: b) applying a coating (7) on the second surface portion (5) of the exposed surface (3) of the layer stack (2), and The coating (7) has a polarity that is the same as or equivalent to the second polarity.

2. The method according to claim 1, wherein the coating (7) comprises ink and / or adhesive.

3. The method according to any of the preceding claims, wherein the second surface portion (5') of the exposed surface (3) of the layer stack (2) forms a pattern.

4. The method according to any of the preceding claims, wherein the second 3D printable material (5) comprises filler particles.

5. The method according to any of the preceding claims, wherein the first 3D printable material (4) comprises a first thermoplastic polymer and the second 3D printable material (5) comprises a second thermoplastic polymer that is the same as the first thermoplastic polymer.

6. The method according to any of the preceding claims, wherein the first surface portion (4') of the 3D object (1) has visual and / or tactile properties that are different from the properties of the second surface portion (5') of the 3D object (1).

7. The method according to any one of the preceding claims, further comprising the steps of: c) Applying a protective layer on at least the second surface portion (5') of the exposed surface (3) of the layer stack (2).

8. A method according to any one of the preceding claims, wherein the first surface portion (4') of the exposed surface (3) of the layer stack (2) has a first area R1, and the second surface portion (5') of the exposed surface (3) of the layer stack (2) has a second area R2, wherein the first area is larger than the second area. 9 . The method according to claim 8 , wherein a ratio between the second area R2 and the first area R1 is 0.01 to 0.5, preferably 0.03 to 0.3, and more preferably 0.05 to 0.

1.

10. A 3D article (1) comprising a layer stack (2) having an exposed surface (3), wherein the layer stack (2) comprises a first 3D printed material (4) having a first polarity and a second 3D printed material (5) having a second polarity; One of the first polarity and the second polarity corresponds to or is hydrophilic, and the other of the first polarity and the second polarity corresponds to or is hydrophobic; wherein the first 3D printed material (4) forms a first surface portion (4') of the exposed surface (3) of the layer stack (2), and the second 3D printed material (5) forms a second surface portion (5') of the exposed surface (3) of the layer stack (2), wherein the second surface portion (5') of the exposed surface (3) of the layer stack (2) comprises a coating (7), and The coating (7) has a polarity that is the same as or equivalent to the second polarity.

11. The 3D article (1) according to claim 10, wherein the second surface portion (5') of the exposed surface (3) of the layer stack (2) forms a pattern.

12. A lighting device comprising a 3D object (1) according to any one of claims 10 and 11, wherein the 3D object (1) is configured as one or more of the following: (i) at least a part of a housing of the lighting device; (ii) at least a part of a wall of a lighting room; and (iii) an optical element.

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