Fabrication of a mold for replicating a component having a predetermined three-dimensional shape

Abstract

The present invention relates to a method for producing a mold for replicating a component having a predetermined three-dimensional shape, the method comprising the steps of (a) producing a glass-based mold having a predetermined three-dimensional shape by using a moldable nanocomposite comprising an organic binder and glass particles dispersed therein, and (b) replicating the glass-based mold obtained in step (a) by melting a metal inside the glass-based mold or melting a metal outside the glass-based mold and pouring it onto or into the glass-based mold and subsequently cooling, or by pressing the glass-based mold into a malleable metal substrate, thereby obtaining a mold for replicating a component having an inverse of the predetermined three-dimensional shape. Furthermore, the present invention relates to a method for replicating a component having a predetermined three-dimensional shape, in which the mold obtained by the method is used for replicating the component, in which the glass particles of the moldable nanocomposite comprise a first type of glass particles having a diameter ranging from 5 nm to 500 nm.

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a mold for replicating a component having a predetermined three-dimensional shape.Furthermore, the present invention relates to a method for replicating a component having a predetermined three-dimensional shape. [Background technology]

[0002] Polymer components, i.e. components made of polymer materials, can be manufactured on an industrial scale by replication processes. In contrast to subtractive or additive manufacturing processes, replication processes, such as injection molding, do not require any shape-specifying steps during production, and therefore allow for the rapid and scalable production of polymer components. That is, in such replication processes, a thermoplastic or resin is injected into a mold and then hardened, which then predetermines the final three-dimensional shape of the polymer component. In contrast to thermoplastics, resins can result in crosslinked structures upon hardening.

[0003] As mentioned above, a thermoplastic or resin that is in a moldable state when injected into a mold tool to obtain a polymeric component must be curable. In the case of a thermoplastic, curing is achieved by cooling, whereby the softened thermoplastic becomes a polymeric component having a final three-dimensional shape. In the case of a resin, curing is achieved by solidification or polymerization, initiated by an external stimulus such as heat or irradiation, whereby the liquid component(s) of the resin become a polymeric component having a final three-dimensional shape. Because the final three-dimensional shape of the polymeric component is predetermined by the shape of the mold, the final three-dimensional shape is generally referred to as a predetermined three-dimensional shape. Of course, the shape of the mold is the inverse of the final three-dimensional shape of the polymeric component. In other words, the mold has an inverse of the predetermined three-dimensional shape.

[0004] Replication processes, such as injection molding, allow for the formation of highly complex structures, limited only by the surface properties of the tool. In this context, molds have proven particularly suitable as tools, as they are durable enough to be usable to produce thousands of polymer components using the same tool over an extended period of time.

[0005] With costs ranging from over 10,000 to several million euros per tool, mold manufacturing is a cost-intensive step in the production of polymer components by replication processes. Currently, most molds used in industry are obtained by subtractive manufacturing, in particular by CNC machining techniques, such as milling, drilling, or grinding. Additive manufacturing has become increasingly popular in rapid mold manufacturing, a process commonly referred to as rapid tooling. However, given the inadequate surface properties, such as high roughness and the presence of defects, that typically result from the additive manufacturing of metals, rapid tooling has not yet been widely applicable on an industrial scale.

[0006] In this context, Non-Patent Document 1 describes a process for manufacturing a mold for polymer replication, which process involves generating a microstructure in a photoresist by lithography, molding the microstructure into high-temperature silicone, which serves as a mold for making a metal mold, and melting a eutectic alloy of Sn, Ag, and Cu directly inside the silicone under light pressure in an oven, and obtaining the mold after cooling to room temperature.

[0007] Furthermore, Non-Patent Document 2 describes microtransfer molding using a metal stamp.

[0008] Moreover, Non-Patent Document 3 describes high-throughput thermal replication of transparent fused silica glass. [Prior art documents] [Non-patent literature]

[0009] [Non-Patent Document 1] C. Richter et al., Progress in Biomedical Optics and Imaging, 2017, vol. 10061 [Non-patent document 2] PL Schilardi et al., Journal of the Argentine Chemical Society, 2003, vol. 91, pages 143-152 [Non-patent document 3] F. Kotz et al., Progress in Biomedical Optics and Imaging, 2019, vol. 10875 Summary of the Invention

[0010] In view of the above, the present invention aims to overcome the above-mentioned drawbacks associated with the production of molds known in the art. In particular, the present invention has as its basic technical problem the provision of a method for producing molds, which should make it possible to provide molds in a cost-effective manner so as to be industrially scalable, while at the same time providing molds with suitable surface properties, such as low roughness and absence of defects.

[0011] The above-mentioned basic technical problem of the present invention has been solved by providing the embodiments characterized in the appended claims.

[0012] In particular, in one aspect, the present invention provides a method for making a mold for replicating a component having a predetermined three-dimensional shape, the method comprising: (a) fabricating a glass-based mold by using a moldable nanocomposite comprising an organic binder and glass particles dispersed therein; The glass mold has a predetermined three-dimensional shape, and is formed as follows: (i) forming the moldable nanocomposite into a predetermined three-dimensional shape to obtain a primary structure before, during, and / or after curing of the organic binder; (ii) degreasing the primary structure obtained in step (i) by removing the organic binder to obtain a secondary structure having voids formed therein; (iii) optionally filling voids in the secondary structure obtained in step (ii) with at least one glass-forming precursor; (iv) obtaining a glass-based mould by sintering the secondary structure obtained in step (ii) and optionally filled with at least one glass-forming precursor in step (iii); Obtained by; (b) replicating from the glass-based mold obtained in step (a) by melting metal inside the glass-based mold or melting metal outside the glass-based mold and pouring it onto or into the glass-based mold followed by cooling, or by pressing the glass-based mold into a malleable metal substrate, thereby obtaining a mold for replicating the component having an inverse of the predetermined three-dimensional shape; Including, The glass particles of the moldable nanocomposite include a first type of glass particles having a diameter in the range of 5 nm to 500 nm; A method of manufacture is provided.

[0013] Advantageously, the manufacturing method according to the invention, characterized by the process steps defined above, makes it possible to provide molds in a cost-effective manner so that they can be industrially scaled up. This is because the glass-based mold obtained in step (a) is subsequently replicated into a mold in step (b). In other words, according to the invention, the manufacture of the mold itself is a replication process, i.e., step (b) can be repeated several times, if necessary, to obtain two or more molds using the same or different glass-based molds. As a result, the manufacturing method according to the invention does not suffer from the drawbacks particularly known from CNC machining techniques, such as low throughput.

[0014] Advantageously, the manufacturing method according to the present invention, characterized by the process steps defined above, also makes it possible to provide a mold with suitable surface properties, such as low roughness and the absence of defects. This is because a moldable nanocomposite comprising an organic binder and glass particles dispersed therein is used to manufacture the glass-based mold. Because the glass particles of the moldable nanocomposite are not melted, i.e., only the organic binder of the moldable nanocomposite needs to be in a moldable state, the glass-based mold can be manufactured at a relatively low temperature in step (a). For example, when the glass-based mold is manufactured by a replication process using a template made of a polymer material, the template does not decompose. In other words, according to the present invention, the template is not exposed to molten glass or molten metal. On the other hand, the glass-based mold obtained in step (a) is resistant to high temperatures and can therefore be contacted with molten metal in step (b). Since the mold is directly replicated from the glass-based mold, meaning that the mold has the inverse shape of the glass-based mold, the surface properties of the mold are substantially influenced only by the surface properties of the glass-based mold. As a result, the manufacturing method according to the present invention does not suffer from the drawbacks that are particularly known in rapid tooling, such as low resolution and poor surface quality.

[0015] The manufacturing method according to the present invention will now be described in detail together with the specific process steps as defined above.

[0016] In step (a) of the manufacturing method according to the present invention, a glass-based mold is manufactured using a moldable nanocomposite comprising an organic binder and glass particles dispersed therein. The glass-based mold obtained in step (a) has a predetermined three-dimensional shape. According to the present invention, the nanocomposite used to manufacture the glass-based mold is moldable, which means that the organic binder of the nanocomposite is in a moldable state. Due to the moldable state of the organic binder, the moldable nanocomposite can be molded to manufacture a glass-based mold having a predetermined three-dimensional shape.

[0017] According to the present invention, the glass-based mold is obtained by steps (i) to (iv) as defined above in step (a). Before considering steps (i) to (iv) in more detail, the composition of the moldable nanocomposite, which comprises, as an essential part, an organic binder and glass particles dispersed therein, will first be described:

[0018] The organic binder of the moldable nanocomposite is not further limited so long as it is in a moldable state, i.e., it can be transferred to a moldable state, such that the moldable nanocomposite is moldable for the purpose of producing a glass-based mold.

[0019] In one embodiment of the present invention, the organic binder of the moldable nanocomposite is a thermoplastic that can harden upon cooling. Thus, upon cooling, the softened thermoplastic becomes solid and the organic binder is no longer moldable. As a result of the hardening of the thermoplastic used as the organic binder, the primary structure obtained in step (i), as further described below, maintains its shape.

[0020] When the organic binder is a thermoplastic, it can be selected from, but is not limited to, polyesters based on aromatic or aliphatic dicarboxylic acids and diols and / or hydroxycarboxylic acids, polycarbonates based on aliphatic or aromatic diols, polyolefins such as polyethylene, polypropylene, polybutene, polymethylpentene, polyisobutene, poly(ethylene vinyl acetate), ethylene propylene rubber (EPR), poly(ethylene propylene diene), poly(vinyl butyral) (PVB), polyacrylates and polymethacrylates, cycloolefin polymers, and the like, as well as polyamides, polyacetals such as polyoxymethylene, polyethers including aromatic polyethers based on bisphenols such as polyethylene glycol (PEG), or polyurethanes, or combinations thereof.

[0021] In another embodiment of the present invention, the organic binder of the moldable nanocomposite is a resin that can be cured by solidification or polymerization initiated by an external stimulus. In this context, the external stimulus can include heat or radiation, particularly UV radiation. In some cases, mixing can be sufficient as the external stimulus, such as in a two-component resin where the liquid components of the resin exhibit sufficient reactivity with each other. Furthermore, if necessary, the external stimulus can include an initiator added to the organic binder to promote the solidification or polymerization of the organic binder. Suitable initiators are known to those skilled in the art and include, but are not limited to, acetophenones such as 2,2-dimethoxy-2-phenylacetophenone (DMPAP), azo compounds such as azobisisobutyronitrile (AIBN), benzophenone derivatives, fluorescein and its derivatives such as rose bengal, quinones such as camphorquinone, and phosphine derivatives such as diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide. Therefore, the solidification or polymerization initiated by an external stimulus solidifies the liquid component(s) of the resin, so that the organic binder is no longer in a moldable state. When exposed to an external stimulus, depending on the resin used, the resin either solidifies to form a crosslinked structure or polymerizes to form a non-crosslinked structure. In other words, the term "resin" as used herein encompasses not only thermosetting resins but also thermoplastic resins. That is, the resin may include any monomer and / or oligomer and / or polymer composition without limitation. As a result of the curing of the resin used as the organic binder, the primary structure obtained in step (i) as further described below maintains its shape.

[0022] When the organic binder is a resin, it can be selected from, but not limited to, acrylate and methacrylate resins, unsaturated polyester resins, vinyl ester resins, epoxy resins, thiol-ene resins, or polyurethane resins. In particular, when the organic binder is a resin, 2-hydroxyethyl methacrylate (HEMA) or a mixture of 2-hydroxyethyl methacrylate and tetraethylene glycol diacrylate (TEGDA) can be mentioned as the organic binder.

[0023] In addition to the organic binder, the moldable nanocomposite contains, as an essential part, glass particles. The glass particles are dispersed in the organic binder. Dispersion of the glass particles can be achieved by any means known in the art, depending on the organic binder used. When a thermoplastic is used as the organic binder, the thermoplastic may be softened or dissolved in a suitable organic solvent or gas phase before adding the glass particles thereto. When a resin is used as the organic binder, the glass particles can be added directly to the liquid component(s) of the resin.

[0024] In a preferred embodiment of the present invention, the glass particles of the moldable nanocomposite are fused silica glass particles. Fused silica glass is characterized by being composed solely of high-purity amorphous silicon dioxide. In this specification, fused silica glass is understood to mean glass having a mass fraction of silicon dioxide of at least 99% relative to the total mass of the glass and containing less than 15 ppm of typical impurities, such as Al, Ca, Cu, Fe, Na, K, Li, and Mg. That is, fused silica glass is substantially free of any components that are typically added to other types of glass to lower their melting points. Therefore, fused silica glass exhibits high thermal stability and can withstand the temperatures encountered when contacting molten metal in step (b), as described in detail below.

[0025] According to the present invention, the glass particles of the moldable nanocomposite include glass particles having diameters in the range of 5 nm to 500 nm, preferably in the range of 7 nm to 400 nm. These glass particles are also referred to as first type particles. It is the first type particles having diameters in the nanometer range that make a composite comprising an organic binder and glass particles dispersed therein a moldable nanocomposite.

[0026] The glass particles of the moldable nanocomposite can include glass particles having diameters in the range of 2 μm to 50 μm, preferably 2 μm to 40 μm, in addition to glass particles having diameters in the range of 5 nm to 500 nm, preferably 7 nm to 400 nm. These glass particles are also referred to herein as second-type glass particles. When the glass particles include a first type of glass particle and a second type of glass particle, i.e., a bimodal mixture of glass particles, the smaller-sized glass particles can fill the gaps between the larger-sized glass particles. This allows for a more dense packing of the glass particles in the moldable nanocomposite, which in turn results in less shrinkage during sintering in step (iv), as further described below. In principle, the glass particles can also include any other type of glass particle having a diameter different from the diameter of either the first type of glass particle or the second type of glass particle. Such multimodal mixtures of glass particles are also within the scope of the present invention.

[0027] In this specification, the diameter of the first, second, and any other type of particles is to be interpreted as the average diameter measured according to ISO 9276-2. According to the present invention, the glass particles do not need to be (perfectly) spherical. That is, the glass particles can also be spheroidal, i.e., they can be sphere-like. For example, for the first type of particles with a diameter in the range of 5 nm to 500 nm, preferably in the range of 7 nm to 400 nm, this means that these glass particles cannot substantially have a size less than 5 nm in diameter, preferably less than 7 nm in diameter, and cannot substantially have a size greater than 500 nm in diameter, preferably greater than 400 nm in diameter.

[0028] Although not limited thereto, the content of glass particles in the moldable nanocomposite is at least 5 parts by volume, preferably at least 30 parts by volume, and more preferably at least 50 parts by volume, per 100 parts by volume of organic binder. The higher the content of glass particles in the moldable nanocomposite, the higher the packing density of the glass particles in the glass-based mold obtained in step (b), as further described below. Surprisingly, the inventors have found that even if the content of glass particles relative to the organic binder in the moldable nanocomposite is significantly higher, for example, 55 parts by volume or even higher per 100 parts by volume of organic binder, it is still possible to mold the moldable nanocomposite for the purpose of producing a glass-based mold.

[0029] In addition to the organic binder and glass particles dispersed therein, the moldable nanocomposite can optionally include one or more additional agents that facilitate the production of a glass-based mold and its replication in a mold. According to the present invention, the total content of any additional agents in the moldable nanocomposite preferably does not exceed 20% by weight, more preferably 15% by weight or less, even more preferably 10% by weight or less, and even more preferably 5% by weight or less, based on 100% by weight of the total mass of the moldable nanocomposite. That is, the moldable nanocomposite according to the present invention consists essentially of the organic binder and glass particles dispersed therein, including any initiator added to the organic binder. As used herein, the term "consisting essentially of" means that the content of the organic binder and glass particles dispersed therein, including any initiator added to the organic binder, preferably accounts for at least 80% by weight, more preferably at least 85% by weight, even more preferably at least 90% by weight, and even more preferably at least 95% by weight, based on 100% by weight of the total mass of the moldable nanocomposite.

[0030] For example, a dispersing agent can be added to facilitate dispersion of glass particles in the organic binder. Examples of dispersing agents include, but are not limited to, alcohols, nonionic surfactants such as polyoxyethylene alkyl ethers or polyoxymethylenes, and anionic surfactants such as fatty acids and their salts or aliphatic carboxylic acids and their salts, such as stearic acid and its salts or oleic acid and its salts. Another example of a dispersing agent that may be suitable for use in the present invention is 2-[2-(2-methoxyethoxy)ethoxy]acetic acid. The presence of a dispersing agent is not essential according to the present invention. That is, the present invention also encompasses embodiments in which the moldable nanocomposite does not contain any dispersing agent.

[0031] To facilitate debinding of the primary structure in step (ii) as described further below, the moldable nanocomposite preferably further comprises a phase former dispersed in the organic binder. A phase former is a substance that is solid or viscous at room temperature (herein defined as 25°C) and forms an internal phase in the organic binder. Examples of phase formers include alcohols, ethers, and silicone oils, as well as combinations thereof, which have a sufficiently high molecular weight and / or suitable functional groups so as to be solid or viscous at room temperature. As used herein, the term "viscous" is understood to mean a viscosity at room temperature of at least 1 mPa·s as measured according to DIN 53019. The phase former can be removed from the organic binder before or during debinding of the primary structure in step (ii) as described further below, for example, by a heat treatment that results in evaporation or sublimation of the phase former or decomposition of the phase former. Furthermore, the phase former can also be removed by solvent extraction or vapor phase extraction.

[0032] A specific example of a phase former is phenoxyethanol (POE). POE has a viscosity of approximately 30 mPa·s at room temperature, making it a viscous substance. POE can be evaporated at atmospheric pressure at a temperature of 242°C. However, due to its high vapor pressure, a significant amount is already removed at lower temperatures. Furthermore, the aforementioned PEG and 2-[2-(2-methoxyethoxy)ethoxy]acetic acid can also function as phase formers.

[0033] It should be noted that once the primary structure is formed, the organic binder is solid (not liquid, gel-like, or paste-like). As will be appreciated by those skilled in the art, a solid is characterized by an inability to specify its viscosity. As used herein, the moldable nanocomposite does not contain any thickeners or solvents, such as water. According to certain embodiments of the present invention, the moldable nanocomposite does not contain any triglycerides, waxes, paraffins, or plasticizers, such as phthalates and any derivatives thereof.

[0034] To improve the mechanical stability of the glass-based mold obtained in step (a), the moldable nanocomposite can further comprise a powder of a ceramic material or a precursor of a ceramic material dispersed in an organic binder. In this context, the term "powder of a ceramic material" means that the particles contained in the powder are made of a ceramic material. If the moldable nanocomposite comprises a powder of a ceramic material, the particles contained in the powder must have an appropriate diameter, i.e., an appropriate size, in addition to what is outlined above for glass particles. Also, the term "precursor of a ceramic material" means that the ceramic material is formed from the precursor during sintering in step (iv), as further described below. If the moldable nanocomposite comprises a precursor of a ceramic material, the precursor is at least one metal-containing compound, which can be selected from the group consisting of organometallic compounds, metal complexes, and metal salts, or a combination of two or more thereof. That is, the precursor of the ceramic material serves as the metal source of the ceramic material. The means outlined above for dispersing glass particles in an organic binder for the purpose of dispersing the powder and / or precursor of a ceramic material in the organic binder are equally applicable here.

[0035] In step (i), the moldable nanocomposite described in detail above is molded into a predetermined three-dimensional shape before, during, and / or after the organic binder has cured. This results in a primary structure, also called a green compact. Depending on the organic binder used, curing is achieved by cooling or by solidification or polymerization initiated by an external stimulus. The shape of the primary structure obtained in step (i) already reflects the shape of the glass-based mold obtained in step (iv), as further described below.

[0036] Forming the moldable nanocomposite into a predetermined three-dimensional shape can be accomplished by any suitable means known in the art. In particular, the moldable nanocomposite can be formed in step (i) by a subtractive manufacturing process, an additive manufacturing process, a replication process, or a combination thereof. Depending on the process(es) applied, the organic binder containing dispersed glass particles is cured before, during, and / or after forming the moldable nanocomposite.

[0037] In subtractive shaping processes, an organic binder containing dispersed glass particles is cured prior to forming the moldable nanocomposite. In other words, the moldable nanocomposite is formed into a predetermined three-dimensional shape after the organic binder has cured. Suitable subtractive shaping processes include, but are not limited to, laser-based structuring techniques and CNC machining techniques, such as milling, drilling, grinding, sawing, lathing, and polishing.

[0038] In the additive manufacturing process, an organic binder containing dispersed glass particles is cured during the formation of the moldable nanocomposite. In other words, the moldable nanocomposite is formed into a predetermined three-dimensional shape while the organic binder is curing. Suitable additive manufacturing processes include, but are not limited to, selective laser sintering and selective laser melting, fused filament fabrication (also known as fused deposition modeling), stereolithography, two-photon polymerization, inkjet printing, and volumetric printing techniques.

[0039] In the replication process, the organic binder containing dispersed glass particles is cured after molding of the moldable nanocomposite. In other words, the moldable nanocomposite is molded into a predetermined three-dimensional shape before the organic binder is cured. Suitable replication processes include, but are not limited to, casting, injection molding, (injection) compression molding, extrusion, thermoforming, cold or hot drawing, hot embossing, nanoimprinting, and blow molding.

[0040] In one embodiment of the present invention, the moldable nanocomposite is formed in step (i) by casting the moldable nanocomposite onto a template, followed by curing. The template has an inverse of a predetermined three-dimensional shape; that is, the shape of the template is the inverse of the final three-dimensional shape of the component to be replicated. The template therefore has the shape of the component replication tool. Thus, in this embodiment, the moldable nanocomposite is formed in step (i) by a replication process.

[0041] The present invention is not further limited as far as the material of the template is concerned. As mentioned above, the template is not exposed to molten glass or molten metal, so there are no particular limitations regarding the temperature resistance of the material, as long as the template can be replicated into a glass-based mold in step (i).

[0042] For example, the template may be made of, but is not limited to, a polymeric material. The polymeric material may be derived from a thermoplastic or a resin. In this specification, the term "polymeric material" should not be construed as including only carbon-based polymers. For example, the term "polymeric material" also includes silicon-based polymers (also known as silicones), such as polysiloxanes. If necessary, the polymeric material may be at least partially crosslinked to provide the template with sufficient mechanical stability. Partial crosslinking can be achieved by using a thermosetting resin, such as a suitable silicone resin having at least three or more reactive functional groups per molecule, at least to some extent.

[0043] If desired, the template can be previously obtained by subtractive manufacturing processes, additive manufacturing processes, replication processes, or a combination thereof. In this context, the means outlined above for forming moldable nanocomposites are equally applicable here.

[0044] For example, the template can be previously obtained by, but is not limited to, microlithography. In microlithography, a photoresist on a substrate covered with a mask is irradiated. The photoresist can be either positive or negative. A negative photoresist is insoluble in a developer if it has been previously irradiated; that is, the areas of the photoresist that have been irradiated through the mask are retained on the substrate to form the template. A positive photoresist is insoluble in a developer if it has not been previously irradiated; that is, the areas of the photoresist that have not been irradiated through the mask are retained on the substrate to form the template. Suitable subtractive manufacturing processes include, but are not limited to, the CNC machining techniques, laser cutting, and water jet cutting described above. Suitable additive manufacturing processes include, but are not limited to, selective laser sintering and fused filament fabrication, two-photon polymerization, direct laser writing, and lithography, particularly stereolithography, as described above.

[0045] When the template is previously obtained by a replication process, the template is replicated from an existing component having a predetermined three-dimensional shape. In this specification, the existing component can be identical to the component to be replicated. As with the template, the existing component can be made of a polymer material. Furthermore, as with the template, the existing component can be previously obtained by a subtractive manufacturing process, an additive manufacturing process, a replication process, or a combination thereof. In this context, the considerations outlined above for the template are equally applicable to the existing component. The existing component can be replicated into the template by using a thermoplastic or resin. To do so, a liquid component(s) of softened thermoplastic or resin is cast onto the existing component. Then, by hardening, a template made of a polymer material is obtained. As mentioned above, the polymer material not only includes carbon-based polymers, but also, for example, silicon-based polymers.

[0046] As already mentioned above, one or more subtractive manufacturing processes, additive manufacturing processes, and replication processes can be combined to form a moldable nanocomposite into a predetermined three-dimensional shape. For example, if a moldable nanocomposite is formed by a replication process and the primary structure has visible artifacts due to the replication process, a subtractive manufacturing process or an additive manufacturing process can be applied to the primary structure as a post-process. In particular, such post-processing can be easily applied when the primary structure is obtained by casting the moldable nanocomposite against a template. Suitable means for post-processing are known to those skilled in the art and include, but are not limited to, CNC machining techniques, as mentioned above. The above considerations are equally applicable to templates and existing components.

[0047] In step (ii), the primary structure obtained in step (i) is degreased by removing the organic binder, thereby obtaining a secondary structure (also referred to as a degreased body). As a result of degreasing, i.e., removing the organic binder, voids are formed in the secondary structure.

[0048] Depending on the organic binder used, the primary structure obtained in step (i) can be degreased in step (ii) by heat treatment, chemical reaction, vacuum, solvent extraction, or gas phase extraction, or a combination thereof. For example, the primary structure can be first immersed in a solvent for solvent extraction and then heat treated. In principle, any means can be applied that can remove the organic binder without adversely affecting the glass particles forming the secondary structure and, if present, the powder and / or precursor of the ceramic material. In this context, a person skilled in the art will routinely select appropriate conditions to apply to remove the organic binder in step (ii).

[0049] For example, when debinding is performed by heat treatment, the temperature applied during debinding is typically in the range of 100°C to 600°C, e.g., 150°C to 550°C, the heating rate is typically in the range of 0.1°C / min to 5°C / min, e.g., 0.5°C / min to 1°C / min, and the holding time is typically in the range of 2 minutes to 12 hours, depending on the size of the resulting glass-based mold. If the size of the resulting glass-based mold is quite small, even a few seconds may be sufficient to debinding the primary structure in step (ii). The heat treatment can also be performed in stages. In accordance with the above considerations, debinding by heat treatment can be further facilitated by reducing the pressure, i.e., a pressure lower than atmospheric pressure, which increases the volatility of the organic binder.

[0050] After removal of the organic binder, the glass particles and, if present, the powder and / or precursor of the ceramic material are attached to each other by hydrogen bonds, which provides mechanical stability to the secondary structure. Considering the size of the glass particles, their diameters in the nanometer range, they have a high specific surface area that allows for sufficient interactions to maintain the mechanical stability of the secondary structure.

[0051] Before or during removal of the organic binder in step (ii), the phase former, if present, is removed from the primary structure, for example by evaporation or sublimation, or by decomposition. If present, removal of the phase former can also be achieved by solvent extraction or gas phase extraction. In principle, the same means as those described above in connection with the removal of the organic binder can be applied.

[0052] If a phase former is present, removal of the phase former facilitates debinding of the primary structure in step (ii). This is because pores are generated in the primary structure when the internal phase in the organic binder formed by the phase former is removed. These pores can then be used to remove the remaining organic binder in a more controlled manner. This reduces the risk of damage to the secondary structure, especially when thick structures are employed. The same applies when the organic binder is removed in multiple steps. For example, if the organic binder is a combination of two or more binder components that exhibit different thermal decomposition behaviors, debinding can be performed sequentially. In this case, after removing the first binder component, i.e., the binder component with the lowest decomposition temperature, the pores generated in the primary structure after removal of the first binder component facilitate the removal of the remaining binder component(s).

[0053] In an optional step (iii), the voids of the secondary structure obtained in step (ii) can be filled with at least one glass-forming precursor. The at least one glass-forming precursor, also referred to as a filler, must have an appropriate size so that it can be introduced into the voids formed in the secondary structure. By filling the voids of the secondary structure with at least one glass-forming precursor, shrinkage of the secondary structure during sintering in step (iv), as described further below, can be reduced. Furthermore, by selecting an appropriate glass-forming precursor, it is possible to increase the hardness of the obtained glass-based mold and / or change its thermal expansion coefficient, for example, to minimize the thermal expansion coefficient. In this specification, the at least one glass-forming precursor is not further limited and can be appropriately selected based on the intended purpose.

[0054] Silicon-based glass-forming precursors, such as, but not limited to, tetraethyl orthosilicate (Si(OC2H5)4) (also referred to as TEOS), can be used. In particular, glass-forming precursors that form glasses indistinguishable from those of the glass particles in the moldable nanocomposite can be used herein, but glass-forming precursors that form glasses different from those of the glass particles in the moldable nanocomposite can also be used herein. For example, when the moldable nanocomposite contains fused silica glass particles as the glass particles, titanium-based glass-forming precursors, such as tetraethyl orthotitanate (Ti(OC2H5)4), can also be used. Other metal alkoxides that can be used herein include titanium isopropoxide, titanium ethoxide, zirconium ethoxide, aluminum isopropoxide, vanadyl isopropoxide, niobium ethoxide, tantalum ethoxide, and potassium tert-butoxide. Further suitable glass-forming precursors are known to those skilled in the art and can be used herein as well.

[0055] When the glass particles in the moldable nanocomposite are fused silica glass particles and the voids of the secondary structure are filled with a silicon-based glass-forming precursor such as TEOS, a glass-based mold made of high-purity fused silica glass with a density comparable to that of conventionally processed fused silica glass can be obtained. As a result, the glass-based mold obtained in step (a) has particularly high resistance to high temperatures. Even if the secondary structure is not filled with a glass-forming precursor in step (iii), the Vickers hardness of the glass-based mold obtained after sintering in step (iv) is comparable to that of conventionally processed fused silica glass.

[0056] In step (iii), the voids of the secondary structure can be filled with at least one glass-forming precursor by immersing the secondary structure in a solution containing at least one glass-forming precursor, by exposing the secondary structure to physical or chemical vapor deposition in an atmosphere containing or producing at least one glass-forming precursor, or a combination thereof. However, in principle, any other filling process can be applied in this regard as well. For example, a sol-gel process can also be applied. Optionally, depending on the at least one additive used to fill the voids of the secondary structure in step (iii), the secondary structure can first be immersed in a solution containing one of the glass-forming precursors and then exposed to physical or chemical vapor deposition containing or producing another one of the glass-forming precursors. The voids of the secondary structure can be filled with at least one glass-forming precursor, even before the debinding of the primary structure is complete. In this case, it is the partially debound primary structure that is filled with at least one glass-forming precursor.

[0057] In step (iv), the secondary structure obtained in step (ii) and optionally filled with at least one glass-forming precursor in step (iii) is sintered, thereby obtaining a glass-based mold.

[0058] Suitable sintering conditions are known to those skilled in the art and are routinely selected as appropriate. Depending on the size of the resulting glass-based mold, the temperature applied during sintering typically ranges from 700°C to 1600°C, the heating rate typically ranges from 1°C / min to 10°C / min, e.g., 5°C / min, and the holding time typically ranges from 0.5 hours to 8 hours, e.g., 4 hours. When the moldable nanocomposite includes a precursor of a ceramic material dispersed in an organic binder and / or when the voids of the secondary structure are filled with a glass-forming precursor in step (iii), the secondary structure can be pre-sintered at an intermediate temperature to convert the precursor of the ceramic material into a ceramic material and / or the glass precursor into glass. For example, pre-sintering can be performed at a temperature ranging from 400°C to 700°C.

[0059] When the glass particles dispersed in the moldable nanocomposite are fused silica glass particles, both a relatively fast heating rate and a relatively fast cooling rate can be selected in view of the low thermal expansion coefficient of fused silica glass and in view of its high thermal shock resistance.

[0060] According to the present invention, sintering does not require the application of pressure. On the contrary, the sintering in step (iv) can be suitably carried out at a pressure lower than atmospheric pressure, for example, at a pressure of at most 0.1 mbar, preferably at a pressure of at most 0.01 mbar, particularly preferably at a pressure of at most 0.001 mbar. Since sintering can be carried out at atmospheric pressure or even lower pressure, there are no specific requirements to be met in the present invention regarding the sintering furnace.

[0061] After sintering, the resulting glass-based form can be cooled to room temperature and subsequently replicated into a mold in step (b) as further described below.

[0062] In step (b) of the manufacturing method according to the present invention, the glass mold obtained by carrying out steps (i) to (iv) in step (a) is replicated by melting metal inside the glass mold or melting metal outside the glass mold and pouring it onto or into the glass mold, followed by cooling, or by pressing the glass mold into a malleable metal substrate. This results in a mold for replicating a component. The mold has an inverse of the predetermined three-dimensional shape of the component to be replicated. A mold obtained by pouring molten metal onto the glass mold according to the present invention is shown in FIG. 1.

[0063] As far as the metal is concerned, the invention is not further limited, for example the metal can be selected from the group consisting of nickel, aluminum, copper, zinc and tin, or can be an alloy of these or other metals, such as brass, bronze or the multi-component alloy AlMgSiMn.

[0064] The shape of the glass-based mold corresponds to the shape of the component to be replicated, and accordingly, the metal can be melted inside the glass-based mold or melted outside the glass-based mold and poured onto or into the glass-based mold. After this is completed, the metal is cooled and solidified. Alternatively, the glass-based mold can be pressed into a metal substrate, if desired. For pressing purposes, the metal substrate must be malleable at either room temperature or at elevated temperatures. Suitable pressable metals include, but are not limited to, aluminum and copper. The mold can be used as obtained and does not require any post-processing. However, the mold can be subjected to post-processing, for example, by subtractive or additive manufacturing processes, for example, to remove features present in the template for manufacturing the glass-based mold or to add features not present in the template.

[0065] In another aspect, the present invention provides a method for replicating a component having a predetermined three-dimensional shape. In the replication method according to the present invention, a mold obtained by the manufacturing method according to the present invention as described above is used to replicate the component. The replicated component is shown in Figure 2 together with the mold used to replicate the component.

[0066] According to the present invention, the mold obtained according to the present invention can be used to replicate components by any replication process known in the art, for example, but not limited to, injection molding, blow molding, hot embossing, thermoforming, or injection compression molding.

[0067] The invention is not further limited as far as the material of the components to be replicated is concerned: in a preferred embodiment of the invention, the replicated components are made of a polymer material, which can be of thermoplastic or resin origin, as outlined above for the template.

[0068] The present invention makes it possible to provide molds using the above-described manufacturing method in a cost-effective manner so as to be industrially scalable, while at the same time providing molds with suitable surface properties, such as low roughness and the absence of defects. In contrast to manufacturing methods known in the art, the predetermined three-dimensional shape of the component to be replicated is transferred to the mold without the need for any shape-specifying step, as is required in subtractive or additive manufacturing. Surprisingly, the transfer of the predetermined three-dimensional shape can be achieved based on a glass-based mold having a predetermined three-dimensional shape obtained during manufacturing. Once the glass-based mold is obtained, the process of replicating from the glass-based mold to the mold can be repeated multiple times, as needed, using the same or different glass-based molds.

[0069] The present invention also makes it possible to provide, using the replication method described above, replicated components suitable for use in various technical fields, in particular in the optical field where high precision is essential, such as lenses, due to the suitable surface properties of the mold that are transferred to the replicated components. [Brief explanation of the drawings]

[0070] [Figure 1] 1A and 1B show (a) a glass-based mold and (b) a mold obtained by pouring molten metal onto the glass-based mold according to the present invention. [Figure 2] Figure 1 shows the replicated components along with the mold used to replicate the components. The replicated components are made of poly(methyl methacrylate). [Figure 3] 1A-1C are diagrams showing the schematic manufacturing of the molds obtained in the examples described below. [Figure 4] 1 shows an evaluation of the molds obtained in the examples described below: (a) white light interferometry of the molds; and (b) microscope images of the molds. DETAILED DESCRIPTION OF THE INVENTION [Example]

[0071] The present invention is further illustrated by, but not limited to, the following examples.

[0072] First, microfluidic channels were obtained by microlithography for the components to be replicated. To replicate the microfluidic channels into templates, a polydimethylsiloxane-based two-component resin was cast into the microfluidic channels and subsequently mixed as an external stimulus to initiate curing, i.e., solidification, resulting in a crosslinked structure.

[0073] The template was then replicated using a moldable nanocomposite containing an organic binder and glass particles dispersed therein. A commercially available moldable nanocomposite was used ("Glassomer L50," a fused silica nanocomposite that is liquid at room temperature and can be hardened by solidifying with UV radiation). To replicate the template into a glass-based mold, the moldable nanocomposite was cast into the template and then cured, i.e., solidified with UV radiation. After debinding by heat treatment and sintering, a glass-based mold made of high-purity fused silica glass was obtained. The moldable nanocomposite used herein enabled easy replication from the template into a temperature-stable glass-based mold.

[0074] Nickel was then melted at a temperature of 920 °C and poured onto the glass mold for glass-to-mold replication. After cooling to room temperature, a high-quality mold was obtained, which could be used as-is to replicate microfluidic channels as replicating components.

[0075] The fabrication of the mold obtained herein is shown schematically in FIG.

[0076] Figure 4 shows (a) white light interferometry and (b) microscopy images, which demonstrate that the mold obtained here had the microfluidic channel geometry replicated with high fidelity.

Claims

1. 1. A method for manufacturing a mold for replicating a component having a predetermined three-dimensional shape, comprising: (a) fabricating a glass-based mold by using a moldable nanocomposite comprising an organic binder and glass particles dispersed therein; The glass mold has the predetermined three-dimensional shape, and is formed as follows: (i) forming the moldable nanocomposite into the predetermined three-dimensional shape to obtain a primary structure before, during, and / or after curing of the organic binder; (ii) removing the organic binder to degrease the primary structure obtained in step (i), thereby obtaining a secondary structure having voids formed therein; (iv) sintering the secondary structure obtained in step (ii) to obtain the glass-based mold; obtained by: (b) replicating from the glass-based mold obtained in step (a) by melting a metal inside the glass-based mold or melting a metal outside the glass-based mold and pouring it onto or into the glass-based mold followed by cooling, or by pressing the glass-based mold into a malleable metal substrate, thereby obtaining the mold for replicating the component, which has an inverse of the predetermined three-dimensional shape; Including, The method of manufacturing, wherein the glass particles of the moldable nanocomposite comprise a first type of glass particles having a diameter ranging from 5 nm to 500 nm.

2. The method of claim 1 , wherein the organic binder of the moldable nanocomposite is a thermoplastic that can harden upon cooling.

3. The method of claim 1 , wherein the organic binder of the moldable nanocomposite is a resin that is curable upon solidification or polymerization initiated by an external stimulus.

4. The method of any one of claims 1 to 3, wherein the glass particles of the moldable nanocomposite are fused silica glass particles.

5. The method according to any one of claims 1 to 4, wherein the diameter of the first type of glass particles is in the range of 7 nm to 400 nm.

6. 6. The method of claim 1, wherein the glass particles of the moldable nanocomposite include, in addition to the first type of glass particles, second type of glass particles having a diameter in the range of 2 μm to 50 μm.

7. 7. The method of claim 1, wherein the moldable nanocomposite further comprises a phase former dispersed in the organic binder, the phase former being solid or viscous at room temperature and forming an internal phase in the organic binder.

8. The method of any one of claims 1 to 7, wherein in step (i), the formable nanocomposite is formed by a subtractive manufacturing process, an additive manufacturing process, a replication process, or a combination thereof.

9. 9. The method of any one of claims 1 to 8, wherein in step (i), the moldable nanocomposite is molded by casting the moldable nanocomposite into a template and subsequently curing, the template having an inverse of the predetermined three-dimensional shape.

10. The method of claim 9 , wherein the template is made of a polymer material.

11. The method of claim 9 or 10, wherein the template is previously obtained by a subtractive manufacturing process, an additive manufacturing process, a replication process, or a combination thereof.

12. In step (ii), the primary structure obtained in step (i) is degreased by heat treatment, chemical reaction, reduced pressure, solvent extraction or gas phase extraction, or a combination thereof. The manufacturing method according to any one of claims 1 to 11.

13. Further comprising step (iii):

13. The method according to claim 1, wherein in step (iii) voids of the secondary structures obtained in step (ii) are filled with at least one glass-forming precursor before sintering the secondary structures in step (iv).

14. A method for replicating a component having a predetermined three-dimensional shape, comprising using a mold obtained by the manufacturing method according to any one of claims 1 to 13 for replicating the component.

15. 15. The replication method of claim 14, wherein the component is replicated by injection molding, blow molding, hot embossing, thermoforming, or injection compression molding.

16. 16. A method according to claim 14 or 15, wherein the replicated components are made of a polymer material.

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