WO2024041782A1

WO2024041782A1 - Method for printing three-dimensional structures with reduced processing effort

Info

Publication number: WO2024041782A1
Application number: PCT/EP2023/067623
Authority: WO
Inventors: Frank Virus
Original assignee: Tesa Se
Priority date: 2022-08-25
Filing date: 2023-06-28
Publication date: 2024-02-29
Also published as: DE102022121548A1

Abstract

The invention relates to a method for producing a three-dimensional target structure using a 3D-printing device, comprising the method steps: a) generating at least one three-dimensional support structure using the 3D-printing device by discharging at least a first material, b) applying an adhesive on a portion of the surface of the support structure in order to obtain a prepared support structure (14a-c) with a surface adhesive layer, c) generating a three-dimensional target structure (18) using the 3D-printing device by discharging at least a second material, wherein the second material is at least partially administered on the adhesive layer of the prepared support structure (14a-c), and d) detaching the support structure from the target structure (18) in the region of the adhesive layer.

Description

Method for printing three-dimensional structures with reduced processing effort

The invention relates to a method for producing a three-dimensional target structure with a 3D printing device and to the use of an adhesive in a 3D printing process to reduce the processing effort and/or to increase the surface quality when separating the target structure. Also disclosed are a 3D printing device for use in the corresponding process and a target structure produced or capable of being produced using the corresponding process.

In many different areas of technology, for example in medical and dental technology but also in automotive technology, the use of additive manufacturing processes using 3D printing devices has established itself as an integral part of the production chain in recent decades, both in the context of series production as well as in the production of prototypes and models. The advantages of such 3D printing processes arise in particular from the possibility of flexible production of desired target structures in a comparatively time- and cost-efficient manner, at least for individual productions. In particular, additive manufacturing makes it possible to produce complex and delicate structural components in a time-efficient manner with a high level of precision, which is usually not achievable with a variety of conventional manufacturing methods with comparable effort.

Various 3D printing processes are known to those skilled in the art, among which the so-called material extrusion processes, in particular the so-called melt deposition processes (Fused Deposition Modeling (FDM) or Fused Filament Fabrication (FFF)) have proven to be particularly powerful for many applications . In melt layering, the target structure is built up in layers from one or more melts, for example polymer melts or metal melts. In the 3D printing devices used here, the shaping is usually carried out in layers by a discharge unit, which is also referred to as a print head, whereby the melt can be provided, for example, via an extruder or a comparable unit.

In practice, many 3D printing processes, especially melt deposition processes, regularly face the challenge of complex Target structures, in particular target structures with overhangs and filigree structural elements, have to be supported in the printing process due to production in order to enable material to be discharged in layers and to minimize or even completely avoid the risk of individual structural parts of the target structure breaking apart or breaking off or their distortion.

The printing of such complex structural parts is therefore regularly associated with a higher manufacturing effort, with each support structure created increasing the material consumption and the post-processing effort, since the support structures have to be removed from the target structure at the end of production. When creating support structures as part of printing planning, there is often a conflict of objectives between a sufficient stabilization effect through comprehensive support and the fundamentally desirable reduction in the number of support structures to avoid waste and additional work steps, which directly results in a reduction in manufacturing costs.

Basically, two different concepts for support structures are known from the prior art, which differ primarily in the melting material used for their production.

On the one hand, the support structures can be made from different materials than the target structures. However, in many processes, for example in the case of material extrusion processes, a number of separate discharge units and associated material supply systems corresponding to the number of materials used must be provided. In this case, the expenditure on equipment, the acquisition costs and the maintenance costs for corresponding more complex 3D printing devices increase.

The great advantage of using different materials for support structures and target structure becomes apparent during post-processing, ie when separating the target structure, since the different physico-chemical properties of the materials enable easier separation, for example different melting points or solubilities. For example, by using materials that are soluble in solvents, for example water, the support structures can be relatively easily separated from the target structure after the printing process by placing the printed product in the appropriate solvent. The supporting structures dissolve in the solvent, so that the target structure can be removed from the solvent essentially without leaving any residue In some cases there is no need to even finish the surface. However, the complete dissolution of the support structures in the solvent regularly requires a lot of time, so that the absolute duration of the manufacturing process of the target structure is significantly increased, which, in addition to the need for solvent, the additional waste and the lack of recyclability of the support material, is regularly viewed as a disadvantage.

Alternatively, support structures can also be made from the same material as the target structure. By using such support structures of the same material to stabilize the target structures, advantageously no additional material melts are required, which would, for example, require separate discharge units and material supply systems in the 3D printing device. In this respect, such support structures can in particular minimize the expenditure on equipment in relation to the 3D printing device.

However, a major disadvantage when using support structures made of the same material is the particularly complex post-processing of the target structure, which is necessary in this case in order to produce sufficient surface quality. The same physico-chemical properties of the target and support structures make separation more difficult and in particular chemical separation, for example by dissolving the support structures, is not possible.

Instead, the support structures usually have to be removed mechanically, for example using cutting devices such as scissors or knives, whereby the additional time required, especially with complex target structures, in some cases even exceeds the absolute printing time of these structures. In addition, it is usually difficult to avoid residues on the target structure during post-processing, so that the surface quality of the end product, especially when producing shape-critical components, is regularly perceived as inadequate without subsequent processing steps such as grinding.

Despite the fundamental advantages of the concepts known from the prior art for the use of support structures in supporting target structures and the methods carried out with them for producing three-dimensional target structures with 3D printing devices, these are therefore perceived as disadvantageous in many respects, in particular with regard to the duration of the Separation process of the support structures and the associated additional manufacturing costs. In addition, the processes known from the prior art often do not enable efficient recycling of the for Materials used for support structures because they are present dissolved in the solvent, for example. In addition, insufficient preparation can lead to defects on the surface of the target structures, which in the worst case can even make it necessary to recreate the target structures. There is therefore a constant need to improve the corresponding additive manufacturing processes and the 3D printing devices used.

The primary object of the present invention was accordingly to eliminate or at least reduce the disadvantages of the prior art described above.

In particular, it was the object of the present invention to provide a method for producing a three-dimensional target structure with a 3D printing device, which can be operated in a more time- and cost-efficient manner compared to methods known from the prior art, in particular the detachment of the in the method Support structures used should be easier, faster and more reliable to implement compared to the state of the art.

In this respect, it was an object of the present invention that the support structures used in the method to be specified should have a high mechanical strength despite the easier removal during the printing process and that excellent bond strength between the target structure and the support structure should be achievable in the method to be specified.

It was also an object of the present invention that, in the method to be specified, the effort required for processing the target structures produced in order to obtain advantageous surface qualities should be reduced. In this respect, it was an object of the present invention that the target structures to be produced using the method to be specified should not have any residues of the support structures after separation, so that in particular no or only little post-processing of the target structure should be necessary in order to obtain an excellent surface quality of the target structure, Desirably, the risk of detachment-related defects in the surface of the target structure should also be reduced.

In this context, it was also an object of the present invention that, in the method to be specified, ideally no additional aids for removing the Support structures, such as solvents or cutting tools, should be needed.

It was also an object of the present invention that, in comparison to conventional processes, the waste generated should be reduced as much as possible, in particular by avoiding the use of solvents. In this respect, it was also an object of the present invention to reduce the energy consumption required in the method to be specified. In this respect, particularly in the series production of target structures, multiple use of the same support structures for a large number of target structures should be made possible.

In addition, it was an object of the present invention to specify the use of an adhesive in a 3D printing process to reduce the processing effort and/or to increase the surface quality when separating the target structure.

It was a secondary object of the present invention to provide a 3D printing device that is particularly suitable for carrying out the method.

It was a further secondary object of the present invention to specify a target structure produced or capable of being produced using the corresponding method.

The inventors of the present invention have now found that the above tasks can surprisingly be achieved if, in a method for producing a three-dimensional target structure with a 3D printing device, an adhesive layer is provided as an easily separable layer between the support structure and the target structure in order to To be able to quickly and easily detach the support structure from the target structure after the printing process without negatively influencing the necessary support effect during the manufacturing process, as defined in the claims.

The above-mentioned objects are thus achieved by the subject matter of the invention, as defined in the claims. Preferred embodiments according to the invention result from the subclaims and the following statements.

Such embodiments, which are referred to below as preferred, are combined in particularly preferred embodiments with features of other embodiments designated as preferred. Are therefore particularly preferred Combinations of two or more of the embodiments described below as particularly preferred. Also preferred are embodiments in which a feature of one embodiment that is designated as preferred to some extent is combined with one or more further features of other embodiments that are designated as preferred to some extent. Features of preferred 3D printing devices, target structures and uses result from the features of preferred methods.

The invention relates to a method for producing a three-dimensional target structure with a 3D printing device, comprising the method steps: a) generating at least one three-dimensional support structure with the 3D printing device by discharging at least a first material, b) applying an adhesive to a portion of the surface of the Support structure for obtaining a prepared support structure with a superficial adhesive layer, c) generating a three-dimensional target structure with the 3D printing device by discharging at least one second material, the second material being at least partially applied to the adhesive layer of the prepared support structure, and d) detaching the support structure from the target structure in the area of the adhesive layer.

The person skilled in the art is familiar with a large number of methods for producing three-dimensional target structures using 3D printing devices. In addition to material extrusion processes, powder-based processes are also known, for example, in which powdered materials are connected to one another, for example using binders or thermal energy. The person skilled in the art understands that the method according to the invention is fundamentally not limited to one of these techniques, but is compatible with various 3D printing devices and 3D printing processes. The method according to the invention initially comprises, independent of the method, producing at least one three-dimensional support structure or a three-dimensional target structure with the 3D printing device by discharging at least a first or second material. In view of the above statements, the creation can basically be done using various 3D printing processes. However, what is relevant for most cases is a method according to the invention because of its high industrial importance and good adaptability for dispensing adhesives, wherein the support structure and/or the target structure, preferably all structures, are produced in one Melt coating process takes place. A method according to the invention is also preferred for essentially all embodiments, wherein the 3D printing device is a melt coating device.

In particular, in the case of melt coating processes described above, three-dimensional structures are generated via a discharge unit of the 3D printing device, which comprises, for example, an extruder, by discharging a material. In most cases, the material is initially fed to the discharge unit in a solid state, for example in the form of a filament, with the discharge unit converting the material into a highly viscous, liquid state by tempering. In this highly viscous state, the material can be dispensed through the outlet opening of the discharge unit to produce the desired geometric shape of the three-dimensional structure and then return to the solid state by cooling. The output of the material to produce target or support structures can take place on a receiving substrate intended to receive the three-dimensional structure.

In most cases, when dispensing the material, the discharge unit is moved by means of a movement unit, for example a linear axis system, in order to obtain the shape of the desired three-dimensional structure by building it up in layers. The discharge unit in such a movement unit is controlled, for example, via an external control unit, which can be arranged on the 3D printing device. The external control unit can, for example, be set up to translate a computer-generated image of the desired three-dimensional target structure and the associated support structures into movements of the movement unit and thus of the discharge unit and to control these accordingly along the contours of the desired three-dimensional structures.

In method step a) of the method according to the invention, one or more support structures are created which serve to support the target structure. The person skilled in the art understands that the support structures can, for example, be created completely in front of the target structure or partially at the same time as the target structure, the latter in particular being a particularly relevant application if the target structure and the support structures are built together layer by layer over large parts of the method become.

The advantages of the method according to the invention arise when only one support structure is used, although in practice it is usually expedient to provide several support structures and then also in the sense of the invention Prepare procedure. A method according to the invention is therefore typical, with two or more, preferably three or more, three-dimensional support structures being produced in the method.

The support structures produced in method step a) comprise the first material as material. In principle, the support structure can also include other materials in addition to the first material, for example in order to optimize the physico-chemical properties or to take into account a material change in the production of the target structure, which is also reflected in the support structures for reasons of efficiency, for example because these essentially at the same time, i.e. in the same layer discharge. In most cases, however, with a view to simple process management and low expenditure on equipment, it is preferred if the support structures consist of the first material.

In a second method step, the method according to the invention comprises applying adhesive to a portion of the surface of the support structure, whereby a prepared support structure with a superficial adhesive layer is obtained, which serves to later connect the support structure to the target structure.

For certain applications, it may at least theoretically be advantageous to carry out the application of the adhesive independently of the 3D printing device, for example manually and/or at least partially automated via an external application device. This applies in particular to applications in which the 3D printing device has limited capacities for applying different materials and, for example, does not include an additional discharge unit for dispensing the adhesive and/or separate material supply systems. In most cases, however, it is explicitly preferred if the adhesive is also applied by a 3D printing device, preferably by the 3D printing device also used to produce the support and target structures. This is not only advantageous for the time efficiency of the manufacturing process itself, but also has an advantageous effect on the precision of the application, since the 3D printing device does not have to be recalibrated and any manufacturing errors can be avoided through manual process steps. Explicitly preferred is therefore a method according to the invention, wherein the adhesive is applied by means of a 3D printing device, preferably the 3D printing device used in method step a) and / or c), the 3D printing device preferably having a separate discharge unit for applying the adhesive includes. Accordingly, an additional or alternative is also preferred Method according to the invention, wherein the adhesive in one

Melt coating process is applied.

In the method according to the invention, the portion of the surface of the prepared support structures covered by the adhesive is expediently usually exclusively that portion of the support structure which, after the three-dimensional target structure has been produced, has a contact surface with it, i.e. the portion of the support structure to which the second material is then applied. The expert calculates this contact surface informally, for example using a computer-generated model of the target structure and the support structure required for the target structure. In most cases, the portion of the surface of the support structure to which the adhesive is applied will be arranged at the tip of the support structure, i.e. opposite to the portion of the support structure resting on the substrate base. If several support structures are used, the advantages of the method according to the invention are particularly clear if all of these support structures are prepared accordingly. A method according to the invention is therefore preferred, wherein the adhesive is applied to a portion of the surface of all support structures.

In some cases, the section of the support structure to which the adhesive is to be applied can also have an irregular surface structure. In these cases, the adhesive can be applied in such a way that the surface structure of the section is reproduced, for example by applying the adhesive in a single layer with a substantially constant thickness. Alternatively, the adhesive can also be used to compensate for unevenness in the partial area of the surface, so that the surface structure of the adhesive layer is independent of the surface structure of the partial section, so that, for example, planar surfaces of the adhesive layer always result regardless of the surface of the partial section. However, a method according to the invention is preferred, wherein the adhesive is applied in a single-layer discharge using the 3D printing device.

The inventors have identified suitable layer thicknesses for the adhesive layer resulting from the application of the adhesive, which, according to the inventors' assessment, enable good adhesion properties of the adhesive layer in most applications as well as good dimensional stability and at the same time good removability, especially when using pressure-sensitive adhesives. A method according to the invention is preferred, in which the adhesive layer of the prepared support structure has an average layer thickness in the range from 0.01 to 5 mm, preferably in the range from 0.1 to 2 mm, particularly preferably in the range from 0.2 to 0.5 mm.

In a third method step, the three-dimensional target structure is generated with the 3D printing device by discharging at least a second material. As explained above, the second material is at least partially applied to the adhesive layer of the prepared support structure, so that after all components have hardened, a target structure is obtained which is at least partially connected to at least one support structure via the adhesive layer. This composite enables good support of the target structure during the printing process, but can be dissolved very easily after completion of the target structure due to the adhesive layer or the predetermined breaking point in the composite created by the adhesive layer, for example by comparatively light manual application of force, especially if a pressure-sensitive adhesive is used Adhesive is used.

Detaching the support structure from the target structure in the area of the adhesive layer significantly reduces the necessary equipment expenditure, since the adhesive layer stabilizes the target structure during production, but forms a predetermined breaking point at the moment of detachment, which can be reliably achieved without the use of separating tools, particularly when using pressure-sensitive adhesives or solvents can be dissolved. In principle, for the simplest and most efficient possible detachment, it is advantageous if the first material of the support structure and the second material of the target structure are completely separated from one another by the adhesive layer, so that the target structure only contacts the prepared support structure in the areas of the adhesive layer. In this respect, the composite of support structure and target structure is preferably only mediated by the adhesive layer. Accordingly, a method according to the invention is particularly preferred, wherein the target structure is produced in such a way that the second material is applied to the prepared support structure in such a way that no contact occurs between the first material and the second material. Alternatively or additionally, a method according to the invention is preferred, wherein the target structure is produced in such a way that the target structure and the support structure are essentially completely separated by the adhesive layer.

In order to achieve the best possible bond strength between the support structure and the target structure during the printing process and at the same time to ensure a particularly simple, solvent-free and residue-free removal of the support structure after the printing process, pressure-sensitive adhesives are particularly suitable for the adhesive used in the method according to the invention, as they are inherently suitable high cohesion When applying the second material, they regularly have advantageous dimensional stability and also ensure a good supporting effect due to their adhesion to the materials, whereby the adhesive properties also enable particularly efficient, residue-free removal, which can usually dispense with complex post-processing steps. A method according to the invention is preferred for essentially all embodiments, wherein the adhesive is a pressure-sensitive adhesive.

According to the expert understanding, a pressure-sensitive adhesive is an adhesive that has pressure-sensitive adhesive properties, ie the property of forming a permanent bond to an adhesive base even under relatively weak pressure. Corresponding pressure-sensitive adhesive layers can usually be removed from the adhesive base after use essentially without leaving any residue and are generally permanently self-adhesive even at room temperature, which means that they have a certain viscosity and stickiness to the touch, so that they wet the surface of a substrate even with slight pressure. Without wishing to be bound to this theory, it is often assumed that a pressure-sensitive adhesive can be viewed as an extremely high-viscosity liquid with an elastic component, which therefore has characteristic viscoelastic properties that lead to the permanent inherent tack and pressure-sensitive adhesive ability described above. It is assumed that with corresponding pressure sensitive adhesives, mechanical deformation leads to both viscous flow processes and the build-up of elastic restoring forces. The proportionate viscous flow serves to achieve adhesion, while the proportionate elastic restoring forces are necessary in particular to achieve cohesion. The connections between rheology and pressure sensitive tack are known in the art and are described, for example, in “Satas, Handbook of Pressure Sensitive Adhesives Technology”, Third Edition, (1999), pages 153 to 203. To characterize the degree of elastic and viscous proportion, the storage modulus (G') and the loss modulus (G") are usually used, which can be determined using dynamic mechanical analysis (DMA), for example using a rheometer, as described, for example, in WO 2015/189323 is disclosed. In the context of the present invention, an adhesive is preferably understood to be pressure-sensitively tacky and thus a pressure-sensitive adhesive if, at a temperature of 23 ° C in the deformation frequency range of 10 ° to 10 ¹ rad / sec, G 'and G "are each at least partially in the range of 10 ³ to 10 ⁷ Pa.

In the context of the present invention, the adhesive used is in principle not limited in terms of its chemical nature, so that the person skilled in the art in the light of can select the intended process parameters from the adhesives known from the prior art. The adhesive used in the method according to the invention should ideally solve the conflict of objectives between strong cohesion and good bond strength that can be achieved, ie adhesion to both the support structure and the target structure, on the one hand, and the simple, preferably residue-free, detachment of the adhesive layer from the target structure on the other hand that fits the respective requirements of the 3D printing process designed by the expert. The expert in the field of adhesive technology is fully familiar with the coordination of the physico-chemical properties of adhesives and can adapt the aspects of cohesion and adhesion to the materials and process conditions used, for example by selecting the polymers used and/or adjusting the degree of crosslinking the adhesive and/or by adjusting the concentration of common additives. With regard to dimensional stability, the inventors suggest that preferred limit values, which have proven themselves in a wide range of printing processes, can be defined via the viscosity of the adhesive. In this respect, a method according to the invention is preferred, wherein the adhesive has a complex viscosity of 10,000 Pa s or more at 23 ° C, preferably 12,000 Pa s or more, particularly preferably 15,000 Pa s or more and / or a complex viscosity at 125 ° C Range from 500 to 4000 Pa s, with the complex viscosity being determined with an oscillatory rheometer at a frequency of 10 rad/s.

For the combination of a particularly advantageous adhesion with good removability, the inventors suggest that particularly suitable procedures are those in which process step d) takes advantage of the fact that the adhesion or tackiness of some adhesives occurs in the course of a so-called “stripping effect”. Stretching of the adhesive can be reduced or an anisotropy of the adhesive is thereby induced, which promotes detachment in a reliable manner, as is known, for example, from adhesive elements that are commercially available under the name “tesa Powerstrips”. A method according to the invention is therefore preferred, wherein the detachment of the support structure from the target structure is promoted or effected by stretching the adhesive in the adhesive layer.

According to the inventors' assessment, synthetic rubber adhesives are particularly suitable for the method according to the invention, ie adhesives which comprise at least partially, preferably predominantly, particularly preferably essentially completely, synthetic rubbers as a polymeric component. Synthetic rubber adhesives are known to those skilled in the art from the prior art and regularly have one have advantageous temperature resistance, usually have favorable dimensional stability at room temperature and show good adhesion to the usual materials used in 3D printing. In addition, synthetic rubber adhesives regularly show a particularly pronounced stripping effect, ie synthetic rubber adhesives can regularly be designed particularly efficiently in such a way that the adhesion or pressure-sensitive tack can be reduced by stretching the adhesive in the adhesive layer. Very particularly preferred is therefore a method according to the invention, wherein the adhesive is selected from the group consisting of synthetic rubber adhesives, which, in the opinion of the inventors, is particularly preferred for essentially all embodiments of the invention. Synthetic rubbers, for example styrene block copolymers, are well known to those skilled in the field of adhesive technology and belong to the larger group of (co-)polymer systems that are often used in adhesives. Suitable synthetic rubbers and adhesives based thereon are commercially available to the person skilled in the art from a wide range of manufacturers, with the person skilled in the art selecting a suitable pressure-sensitive adhesive in light of the specific physico-chemical properties desired for the printing process

According to the inventors' assessment, it can be seen as a great advantage of the method according to the invention that it is particularly easy to use and reuse the separated, old support structures as secondary sources of raw materials. In the method according to the invention, this is made easier in particular by the fact that the support structure, the target structure and the adhesive layer can be separated from one another particularly easily and in many cases essentially without leaving any residue, so that the support structures can be made available for recycling as a whole and not dissolved in solvent or in Individual parts are disassembled. For example, a support structure produced in the method according to the invention can be reused as the first material in a downstream method for the production of further target structures, for example by melting the material and mixing it with a straw made from primary raw material. Accordingly, preference is given to a method according to the invention, wherein the first material of the support structure detached in method step d) is recycled, preferably in method step a) of a downstream method for producing a three-dimensional target structure.

According to the inventors' assessment, it can be seen as an advantage of the method according to the invention that it is not additionally restricted with regard to the type of materials used, so that in principle all materials can be used for the support and target structures that the person skilled in the art can use for the respective 3D printing process as suitable materials are known. However, for the materials used in the process, the inventors have identified materials which have proven to be particularly suitable for use in the process according to the invention and which in particular have good compatibility with or good adhesion to typical adhesives, in particular synthetic rubber adhesives. A method according to the invention is preferred, wherein the first material and/or the second material is selected from the group consisting of thermoplastics, preferably from the group consisting of acrylonitrile-butadiene-styrene, acrylonitrile-styrene acrylate, polyethylene terephthalate, polycarbonate, polypropylene, polyaryl ether ketones , polyetherimides, polyurethanes and polylactides.

For the purpose of keeping the process as simple as possible and minimizing the complexity of the apparatus, the inventors believe that it has proven to be particularly advantageous to make the first material and the second material identical, since in this case, for example, there is a need for a further output unit for the output unit that is different from the first material second material is omitted. This takes advantage of the fact that, in contrast to the prior art, the method according to the invention means that there is no need for complex mechanical processing processes, for example separation processes, even when using identical materials. A method according to the invention is therefore preferred, wherein the first material and the second material are identical.

When using different materials for the target and support structures, the method according to the invention advantageously achieves greater flexibility in the choice of materials, since the first material, for example, does not have to be soluble in a specific solvent, so that, for example, particularly cost-effective materials can be used. In this respect, for example, a method according to the invention is preferred, wherein the first material is essentially insoluble in water.

In accordance with the knowledge of those skilled in the art, the melt coating processes preferred in the context of the present invention in most cases require tempering of the materials used in order to convert them from a solid state of matter into a sufficiently liquid state of matter before discharge. The expert understands that the nature of the materials used in the 3D printing process is subject to certain requirements in practice at the time of application. A material that is too hot, i.e. with a correspondingly low viscosity, In some cases, it may not retain its shape sufficiently after extrusion before cooling. A material whose temperature is too low, i.e. a material with a very high viscosity, can under certain circumstances clog the dispensing unit and/or can only be applied at an insufficient speed. In addition, the structures created in the previous discharge step should be cooled down at least to such an extent that they can survive the subsequent discharge without deformation.

Setting these temperature ranges and choosing an adapted process does not pose any major problems in practice for the person skilled in the art with regard to the materials used, since he or she is familiar with printing these materials and/or can find the corresponding parameters, for example, from the manufacturer's information. What is typical in this respect is a method according to the invention, wherein the first material and/or the second material during discharge has a temperature in the range from 130 to 260 ° C, preferably in the range from 150 to 240 ° C, particularly preferably in the range from 170 to 220 ° C , exhibit.

In the context of the present invention, the person skilled in the art must therefore adapt the process parameters primarily to the adhesive, especially if this is also applied using the 3D printing device. In practice, the optimal parameters will depend significantly on the chemical nature of the adhesives. As a guide for the person skilled in the art, from which he can determine suitable parameters in the context of routine experiments, the inventors suggest temperature ranges with which, according to the inventors' knowledge, reliably high performance for the adhesives commonly used, but in particular for the preferred synthetic rubber adhesives disclosed above Have procedures implemented. In this respect, preference is given to a method according to the invention, the adhesive having a temperature in the range from 110 to 260 ° C, preferably in the range from 120 to 200 ° C, particularly preferably in the range from 130 to 180 ° C, when applied. Additionally or alternatively, a method according to the invention is also preferred, wherein the average temperature of the support structure when applying the adhesive is 120 ° C or less, preferably 60 ° C or less, particularly preferably 30 ° C or less. Alternatively or additionally, a method according to the invention is preferred, wherein the average temperature of the adhesive layer when the second material is applied is 120 ° C or less, preferably 60 ° C or less, particularly preferably 30 ° C or less.

In light of the above statements, the person skilled in the art understands that the invention also includes the use of an adhesive in a 3D printing process Intermediate layer between the target structure to be printed and one or more support structures, to reduce the processing effort and / or to increase the surface quality when separating the target structure.

Also disclosed is a 3D printing device for carrying out the method according to the invention, comprising: i) a first discharge unit with a first material supply system connected thereto for providing a first material to the first discharge unit, ii) a second discharge unit with a second material supply system connected thereto for providing a second Material to the second discharge unit, and iii) a third discharge unit with an associated third material supply system for providing an adhesive to the third discharge unit.

This 3D printing device is particularly suitable for delivering two different materials and an adhesive in the method according to the invention.

The person skilled in the art understands that the 3D printing device is preferably suitable for carrying out the method according to the invention in preferred embodiments and to this extent also includes the features that are advantageous for the method according to the invention. A 3D printing device is therefore particularly preferred, wherein the 3D printing device is a melt coating device.

A 3D printing device is also preferred, wherein the 3D printing device comprises one or more movement units for moving the first discharge unit, second discharge unit and third discharge unit, preferably one or more linear axis systems. A 3D printing device is also preferred, wherein the 3D printing device comprises a receiving substrate which is set up so that three-dimensional structures can be generated on its surface by the 3D printing device.

Finally, a target structure is also disclosed that is produced or can be produced using the method according to the invention, for example a vehicle component, which is characterized by: is characterized by easy manufacturability and an advantageous surface quality after just a short preparation.

Preferred embodiments of the invention are explained and described in more detail below with reference to the accompanying figures. Show:

1 shows a schematic representation of exemplary three-dimensional support structures after their production in a method according to the invention;

2 shows a schematic representation of exemplary prepared support structures after application of a surface adhesive layer in a method according to the invention;

3 shows a schematic representation of a three-dimensional target structure produced on the prepared support structures in a method according to the invention; and

4 shows a schematic representation of a target structure isolated in a method according to the invention and of the support structures detached from the target structure.

Fig. 1 shows a schematic and, for reasons of clarity, greatly simplified side view of support structures 10a, 10b, 10c made of a first material, as can be produced in a method according to the invention for producing a three-dimensional target structure 18 with a 3D printing device in method step a). , whereby in practice the support structures 10a-c are usually produced together, i.e. in parallel layers, with the target structure 18. The person skilled in the art understands that in practice a much larger number of significantly more delicate support structures 10a, 10b, 10c will usually be used, which are often also connected to one another in order to ensure the necessary stability for supporting the target structure 18.

The exemplary method according to the invention visualized by the figures is a melt coating method, wherein the support structures 10a-c were printed using a first discharge unit of the 3D printing device, which is set up to apply the first material. In the exemplary process according to the invention, the first material is acrylonitrile-butadiene-styrene copolymer (ABS).

Method step b) is visualized in FIG all support structures 10a-c, in order to thereby obtain prepared support structures 14a, 14b, 14c, which are provided at their tip with a superficial adhesive layer 16a, 16b, 16c. In the exemplary method according to the invention, the adhesive is applied in a single-layer discharge by means of a second discharge unit of the same melt coating device, the adhesive layers 16a-c in the example shown in FIG. 2 each having a layer thickness of approximately 0.35 mm. In the exemplary method according to the invention, the adhesive is in each case a pressure-sensitive adhesive, namely a synthetic rubber adhesive, the polymer system of which essentially consists of synthetic rubber. In the exemplary method according to the invention, the application takes place at a temperature in the range from 130 to 180 ° C, the exemplary method according to the invention being carried out in such a way that the temperature of the support structures 10a-c at this point essentially already corresponds to room temperature.

3 now shows the previously prepared support structures 14a-c of FIG. 2 with a three-dimensional target structure 18 generated on the prepared support structures 14a-c, which is supported by the prepared support structures 14a-c. The target structure 18 is arranged in sections on the adhesive layers 16a-c of the prepared support structures 14a-c, so that the overhang of the target structure 18 shown in the example cannot break off or be otherwise damaged, since the prepared support structures 14a-c serve to stabilize the target structure 18 , wherein the support structures 10a, 10b, 10c are each connected to the target structure 18 via the adhesive layers 16a-c.

In the example shown, the target structure 18 consists of a second material, namely polylactide (PLA), which in the exemplary method according to the invention is applied via a third discharge unit of the melt coating device in such a way that no contact occurs between the first material and the second material. In this respect, the target structure 18 and the support structures 10a-c are completely separated from one another by the adhesive layers 16a-c.

4 finally visualizes method step d) of the exemplary method according to the invention and shows the isolated target structure 18 and the support structures 10a-c detached from the target structure 18. As part of the exemplary method according to the invention, the connection between the target structure 18 and the respective support structures 10a-c was promoted using the “stipping effect” by stretching the synthetic rubber adhesive of the adhesive layers 16a-c, so that the support structures 10a-c with little application of force can be deducted, For example, manually, so that only any adhesive that may be adhering to the target structure 18 needs to be removed, which can be done, for example, by peeling or rubbing.

In the exemplary method according to the invention, the support structures 10a-c removed in this way are freed from any residues of the adhesive and then recycled so that they can be reused as the first material.

Reference character list

10a-c support structure

12a-c subsection

14a-c prepared support structure 16a-c adhesive layer

18 Target structure

Claims

Expectations

1. A method for producing a three-dimensional target structure with a 3D printing device, comprising the method steps: a) generating at least one three-dimensional support structure (10a-c) with the 3D printing device by discharging at least a first material, b) applying an adhesive to a partial section (12a-c) the surface of the support structure (10a-c) to obtain a prepared support structure (14a-c) with a superficial adhesive layer (16a-c), c) generating a three-dimensional target structure (18) with the 3D printing device by discharge at least one second material, the second material being at least partially applied to the adhesive layer (14a-c) of the prepared support structure (14a-c), and d) detaching the support structure (10a-c) from the target structure (18) in the area of Adhesive layer (16a-c).

2. The method according to claim 1, wherein the adhesive layer (16a-c) of the prepared support structure (14a-c) has an average layer thickness in the range of 0.01 to 5 mm.

3. The method according to any one of claims 1 or 2, wherein the adhesive is applied using the 3D printing device.

4. The method according to any one of claims 1 to 3, wherein the target structure (18) is produced in such a way that the second material is applied to the prepared support structure (14a-c) in such a way that no contact occurs between the first material and the second material .

5. The method according to any one of claims 1 to 4, wherein the detachment of the support structure (10a-c) from the target structure (18) is promoted or effected by stretching the adhesive in the adhesive layer (16a-c).

6. The method according to any one of claims 1 to 5, wherein the first material of the support structure (10a-c) detached in method step d) is recycled.

7. The method according to any one of claims 1 to 6, wherein the first material and the second material are identical.

8. The method according to any one of claims 1 to 7, wherein the adhesive is a pressure-sensitive adhesive.

9. The method according to any one of claims 1 to 8, wherein the adhesive is selected from the group consisting of synthetic rubber adhesives.

10. Use of an adhesive in a 3D printing process as an intermediate layer between the target structure to be printed and one or more support structures, to reduce the processing effort and/or to increase the surface quality when separating the target structure.