Use of particles containing at least one cavity, process for the manufacture of a three-dimensional object, multi-phase material system, particle for use in laser sintering, and, object made of particles that are mutually connected

Abstract

USE OF PARTICLES CONTAINING AT LEAST ONE CAVITY, PROCESS FOR THE MANUFACTURING OF A THREE-DIMENSIONAL OBJECT, MULTIPLE-PHASE MATERIAL SYSTEM, PARTICLE FOR USE IN LASER SINTERIZATION, AND, OBJECT MADE OF PARTICLES THAT ARE MUTUAL CONSTRUCTED OBJECTS BY MUTUAL DIMENSIONS THROUGH MUTUAL Dimensions of layer structuring processes continue to increase while said objects become heavier and are thus less easy to handle and transport. Thin structures can still break outside the total body as a result of their intrinsic weight. The objective of the present invention is, therefore, to create a layer structuring process for the production of a three-dimensional object as well as suitable material systems that improve its handling and transport capacity without imposing substantial restrictions regarding the variety of materials selectable and component stability. Said objective is achieved by the use of particles that contain at least one cavity, whereby the volume of the solid body and, thus, the weight are reduced when compared with solid particles without substantially reducing the stability.

Description

"USE OF PARTICLES CONTAINING AT LEAST LARGE NULLITIES; PROCESS FOR MANUFACTURING A THREE-DIMENSIONAL OBJECT, MULTIPLE-PHASE MATERIAL SYSTEM, PARTICLE FOR USE IN LASER SINTERING, AND, OBJECT MADE OF PARTICLES THAT ARE MUTUALLY CONNECTED" The present invention relates to a process for manufacturing a three-dimensional object in a layered form and to suitable material systems for this purpose according to the preamble of claims 1, 2, 4 and 5, and an object manufactured using this process according to claim 9. Processes and material systems of this type are known from DE 101 08 612 Cl and DE 100 26 955 Al. Processes for manufacturing three-dimensional objects in a layered form are finding increasing fields of application, particularly in: rapid prototyping, rapid fabrication, and rapid manufacturing. These types of processes can be liquid-based, e.g., stereolithography; powder-based, e.g., laser sintering or 3D printing; or solid-layer-based, e.g., laminated object fabrication. What all these processes have in common is that, as the fields of application expand, the dimensions of the objects manufactured with them also continue to grow. In addition, the objects are becoming heavier and therefore more difficult to handle and transport. Thinner structures can even break off from the overall body due to their weight. Therefore, it is an object of the present invention to provide a process for manufacturing a three-dimensional object in the form of layers and suitable material systems that improve handling and transport characteristics while not bringing any significant restriction on the wide variety of selectable materials and the stability of the components. This object is solved by using *perti cutes'que fcobtôwl.pel tf less a cavity. This reduces the volume of solid material and therefore the weight when compared with massive particles without significantly reducing stability. Particles of this type can be efficiently and cost-effectively manufactured from microporous materials, e.g., activated carbon or zeolites, or on an industrial scale and in particle size distributions suitable for said processes by comminution or re-accumulation; for example, emulsion polymerization can be used to manufacture hollow beads in the micrometer range or below on an industrial scale. Industrially manufactured hollow beads can be suitable particles for such production or serve for their manufacture by accumulation, for example, of agglomerates of multiple hollow beads or of at least one hollow bead and at least one solid particle to form suitable particles. Suitable particle size distributions can be achieved by known procedures, e.g., screening, sieving. As for the material of such particles, any material with cavities of a suitable size that occurs naturally or can be manufactured is suitable, e.g., metals, ceramics, or plastics. With respect to the process to be created, the present invention is represented by the characteristics according to claim 2, and with respect to the material to be created, the present invention is represented by claims 4 and 5. The other claims contain other advantageous developments and improvements of the process and material according to the present invention (claims 3 and 6 to 8), as well as an object manufactured by means of the process and materials according to the present invention (claim 9). With regard to the process to be created, the object is solved according to the present invention by carrying out the following steps: application of a layer of : partfeúla's*«0ffl-tfnla target; - Irradiation of a selected portion of the layer corresponding to a cross-section of the object with an energy beam or a jet of liquid in such a way that the particles in the selected portion become mutually connected; - repetition of the application and irradiation steps with a beam or jet for multiple layers in such a way that the connected parts of adjacent layers connect to each other to form the object, in what The particles used contain at least one cavity. In this context, the energy beam can be of any type, e.g., an electron beam or an IR beam, preferably a laser beam, as long as the energy input into the particle layer is high enough to effect particle connection. For this purpose, it is not necessary for the particles to fuse completely in the irradiated area. Initial fusion or the start of a chemical reaction by the energy may also be sufficient. With regard to the liquid used, at least one component of the particles must be soluble in it, or a reaction must be initiated due to interaction with the liquid, such that the particles in the area of ​​impact with the liquid are forced to connect with each other. The term liquid jet will encompass not only a continuous jet, but also individual droplets. In another advantageous development of the process, the irradiation of the particles into a beam or jet is carried out in such a way that the cavities are essentially preserved. For this purpose, it is sufficient to limit the input of energy or liquid in such a way that only one superficial connection of particles without fusion* or-&s9Óruçao«'c<§mJ>tó&ã.«&já efetuada. With regard to the material system to be created, particularly for use in 3D printing, the object is designed according to the present invention in which it contains solid particles and a liquid, wherein at least parts of the particles have the characteristic of forming lasting connections to adjacent particles upon exposure to the liquid, wherein the particles contain at least one cavity. A material system of this type allows the processes described above to be used to accumulate three-dimensional objects that have comparable characteristics to the accumulation of objects from solid particles, but are significantly lighter in weight and thus easier to handle. A lasting connection can be formed by at least some of the particles (e.g., a coating) being, for example, dissolved, induced to react, or partially fused by the liquid upon exposure to the liquid. A material system suitable for use in laser sintering (also called selective laser sintering) consists of particles comprising, at least on part of their surface, a component whose softening temperature is below 100°C and containing at least one cavity. Materials with a softening temperature of this type may include alloys that are used, for example, in fusible bonds (compare e.g. JP 2001143588A), as well as linear carbonic acids with a chain length > 16 (e.g., heptadecanoic acid, melting point 60 to 63°C) or polymers in the broader sense. Particles of this type can be processed quickly and precisely with common laser sintering plants, and objects made from them can be produced using this method. from these they possess good characteristics cie mahusbi<5'«p'oií dau^d ..datf cavities. In the material systems mentioned above, it is advantageous for the particle size distribution curves to have centers of gravity at diameters smaller than 500 µm, preferably at diameters on the order of 10 to 300 µm. Particle sizes of this type can be used to cover virtually all requirements of the application fields known today. Strict precision requirements necessitate that the particle size distribution show little variation and may require small diameters close to the lower threshold mentioned above. In addition, it is advantageous for said material systems if the volume fraction of the particle cavities is at least 30% and at most 90%, preferably at least 50% and at most 80%, of the particle volume. Depending on the material used, this allows for stability of the objects produced while maintaining their weight and ensuring good handling characteristics. It is advantageous for such material systems that the particles comprise crosslinkable polymers, at least on their surface. These can be provided, for example, in the form of a coating. Crosslinking can be initiated by exposure to energy or by the liquid and leads to the formation of a lasting connection to adjacent particles. In the following, the process according to the present invention and the material systems according to the present invention are illustrated in more detail by means of two exemplary embodiments. A suitable material system for laser sintering contains particles made from naturally occurring volcanic zeolites that have been comminuted and sorted to have a diameter distribution with a primary emphasis on 100 µm. Its porosity is approximately... 45%, resulting in a reduction in density refeMè*«2;3«g / Jm 3 .ftosà. g / cm 3Apparent. Mineralogical ingredients: mainly crinoptilolite and mordenite. Chemical composition: mainly SiO2 and Al2O3. These particles were coated with a polyvinyl butyral coating, which has a softening temperature of approximately 66°C, using a known fluidized bed procedure (compare with DE 10313452 Al). The coated particles are applied layer by layer to a target surface. A selected portion of the layer, corresponding to a cross-section of the object, is irradiated with a laser beam in such a way that the particles in the selected portion become mutually connected. Then, the application and beam irradiation steps are repeated for multiple layers, such that the connected parts of adjacent layers link together to form the object. The laser beam (power ~10 Watt (or less if stability requirements are less stringent), feed rate ~5 m / s, laser spot diameter ~0.4 mm) is guided in such a way that the radiation energy thus coupled causes the coating to soften and therefore causes the irradiated particles to connect to each other without fusing the core material. The coating is approximately 0.3 to 0.7 pm thick. A suitable material system for 3D printing contains particles made of hollow PMMA beads that have been produced by emulsion polymerization and coated with polyvinylpyrrolidone (PVP) using a fluidized bed process. The coating is approximately 0.3 to 0.7 µm thick. The particle diameter distribution is primarily focused on 50 µm. The material system contains water as the liquid component. PVP is water-soluble. The coated particles are applied layer by layer in ••• * • •• *•••••• a target surface, a selected part of the cross-section of the object is irradiated with water droplets in such a way that the particles in the selected part become mutually connected, then the application and irradiation steps are repeated for a multiplicity of layers in such a way that the connected parts of adjacent layers connect to each other in order to form the object. In the embodiments of the examples described above, the process according to the present invention and the material systems according to the present invention prove to be particularly well suited for rapid prototyping, rapid tooling, and rapid manufacturing applications in the automotive industry. In particular, they allow for a clear improvement in the handling and stability characteristics of large, finely detailed structures. The present invention should not be limited to the exemplary embodiments illustrated above, but rather is applicable to other exemplary embodiments as well. Thus, it is conceivable, for example, that the cavities of the particles are filled with a medium that is lighter when compared to the cavity wall, e.g., a liquid or gas. Particles in the form of hollow metal beads can also be used. These can be manufactured by the fluidized bed procedure by, for example, spraying a binder suspension – metal powder – onto the styrofoam beads and heating sufficiently for the metal powder to melt and form a solid surface, while the styrofoam evaporates. The resulting surface can be closed or porous.

Claims

CLAIMS 1. Use of particles containing at least one cavity, characterized by being in the process for manufacturing a three-dimensional object in a layered form.

2. Process for manufacturing a three-dimensional object, comprising the following steps: - applying a layer of particles to a target surface; - Irradiation of a selected portion of the layer corresponding to a cross-section of the object with an energy beam or a jet of liquid in such a way that the particles in the selected portion become mutually connected; - repetition of the application and irradiation steps with a beam or jet onto multiple layers in such a way that the connected parts of adjacent layers connect to each other to form the object, characterized by the fact that The particles used contain at least one cavity.

3. Process according to claim 2, characterized in that the particles are irradiated in such a way that the cavities are essentially preserved.

4. Multi-phase material system for use in 3D printing containing solid particles and a liquid; in which at least some of the particles have the characteristic of forming lasting connections to adjacent particles in contact with the liquid, characterized by the fact that the particles contain at least one cavity.

5. Particles for use in laser sintering, comprising, on at least part of its surface, a component whose softening temperature is below 100°C, characterized by the fact that it contains at least one cavity.

6. A material or particle system according to claim 4 or 5, characterized in that the particles have diameters smaller than 500 µm, preferably diameters in the order of 10 to 300 µm.

7. A system of material or particles according to any one of claims 4 to 6, characterized in that the volume fraction of the cavities comprises at least 30% and at most 90%, preferably at least 50% and at most 80%, of the volume of the particles.

8. A system of material or particles according to any one of claims 4 to 7, characterized in that the particles comprise crosslinkable polymers at least on their surface.

9. An object made of particles that are mutually connected, characterized in that it was manufactured by means of a process according to any one of claims 2 to 3 and / or it was manufactured from a system of material or particles according to any one of claims 4 to 8. SUMMARY "USE OF PARTICLES CONTAINING AT LEAST ONE CAVITY, PROCESS FOR MANUFACTURING A THREE-DIMENSIONAL OBJECT, MULTI-PHASE MATERIAL SYSTEM, PARTICLE FOR USE IN LASER SINTERING, AND OBJECT MADE OF PARTICLES THAT ARE MUTUALLY CONNECTED" The dimensions of objects produced through layer-structuring processes continue to increase while said objects become heavier and thus less easy to handle and transport. Thin structures can even break off from the overall body as a result of their intrinsic weight. The objective of the present invention is, therefore, to create a layer-structuring process for the production of a three-dimensional object, as well as suitable material systems that improve its handling and transportability without imposing substantial restrictions on the variety of selectable materials and the stability of the components. Said objective is achieved by using particles containing at least one cavity, whereby the volume of the solid body, and thus the weight, are reduced when compared to massive particles without substantially reducing stability.