EP3898167A1 - Mold composition comprising a sugar component - Google Patents

Abstract

The invention relates to a mold composition comprising at least one sugar component in a weight proportion of at least 20% in relation to the weight of the mold composition and at least one loading material, and to a mold for a molding method, the mold being a compact three-dimensional structure which consists of the mold composition. The invention also relates to a method for molding a workpiece by means of said mold.

Description

MOLD COMPOSITION COMPREHENSIVE OF A SUGAR COMPONENT

The invention relates to a molding composition comprising at least one sugar component, a mold for a molding process from this molding composition, and a method for molding a workpiece with a mold.

BACKGROUND OF THE INVENTION

Molds, in particular lost molds, are used in the molding of workpieces in various molding processes, for example in the production of metallic, ceramic or polymeric workpieces by press, injection molding, casting, injection molding, powder injection molding or, in the case of fiber composite workpieces, by the laminating method . The shape is typically a negative of at least part of the three-dimensional design of a workpiece.

The term “shape” as used herein denotes a model, in particular a lost shape, a lost core or a support structure.

Complex shaped metallic, ceramic or polymer workpieces - e.g. with cavities or so-called undercuts - can usually not be achieved with molds or molds that can be demolded or removed by pressing processes or casting processes because internal or undercut molded parts cannot be removed for mechanical reasons at the end of the molding process. In order to be able to manufacture such workpieces, so-called lost molds or lost mold cores are used in the art, which are removed by dissolving in water or other liquids, by melting or by thermal decomposition or combustion to form liquid, gaseous or free-flowing, powdery decomposition products can. In other cases, a removable tool is technically possible, but not economical compared to a lost mold.

1.Melt core injection molding

Plastics (polymers) are mainly processed in the injection molding process: Mostly thermoplastic, but also thermosetting or elastomeric plastic powders, granules or pastes are heated and compressed to 150 - 300 ° C in a heated cylinder with a piston or rotating screw (extruder) until they are plasticized and then injected into a shaping, water-cooled, mostly steel, two-part cavity at pressures of 500 - 2000 bar. After cooling and curing or vulcanizing, the workpiece can pass through Opening of the cavity can be removed. In order to be able to produce workpieces with cavities or undercuts, lost molds or mold cores are also used here: These cores are made on the one hand from low-melting metal alloys (melting alloys) such as Wood's metal or Roses metal by casting, which are removed from the injection molding by melting or consist, for example, of water-soluble polyacrylate polymers, which in turn were produced by injection molding. Melt-core injection molding can also be used to manufacture fiber-reinforced plastic workpieces, see, for example, EP 1 711 334 A2. When melting out melting alloys, care must be taken to ensure that the metal mold core is stable and malleable for long enough at the selected injection molding temperature and that the plastic workpiece is not subsequently thermally affected at the required melting temperature (Michaeli, W .; Greif, H. ; Kretzschmar, G .; Ehrig, F., Injection Molding Technology, 3rd ed .; Hanser: Munich, 2009).

2. Powder Injection Molding

A further development of the injection molding process for plastics described above is the so-called powder injection molding, which is also known as metal injection molding for sinterable powders such as metallic powders (typically sintered ferrous and non-ferrous metals, hard metals, metal composite materials), ceramic powders (typically ceramics (cermets) , Oxide ceramics, nitride ceramics, carbide ceramics and functional ceramics) also called ceramic injection mol ding and special polymer powders such as Teflon are used. Injection molding compounds consisting of metallic, ceramic or polymeric particles (or mixtures of such particles), auxiliary substances such as lubricants and (organic) binders are used. After the injection molding, the so-called green compact is largely removed by dissolving the binder in water or suitable solvents or by thermal treatment. The resulting, almost binder-free brown product is then sintered to the finished workpiece in a material-specific, thermal process. In a modification of this method, special binders can also remain in the green compact in order to modify the properties of the workpiece. Powder injection molding can also be used to manufacture composite materials, such as fiber composite materials. Analogous to the underlying normal injection molding - as described above - lost molds or mold cores can also be used in powder injection molding in order to be able to produce workpieces with cavities and undercuts ("powder injection molding"; Volker Piotter et al., Wiley Encyclopedia of Composites , 2nd Edition (2012), 4, 2354-2367; "Recent Advances in CIM Technology"; BS Zlatkov et al., Science of Sintering, 40, 2008, 185-195). 3. Pressing

Sinterable metallic, ceramic or polymeric powders, e.g. as described in 2.Powder Injection Molding, can also be processed into workpieces by discontinuous pressing processes, whereby composite materials, e.g. Fiber composite materials can be produced. For this purpose, molding compounds consisting of ceramic, metallic or polymeric particles, auxiliary materials such as e.g. Lubricants and (organic) binders are produced, which are introduced into press molds (press dies) made of wear-resistant steel or hard metals. The molding compounds can be processed dry (dry pressing) or wet (wet pressing), cold (cold pressing), warm (hot pressing) or hot (pressure sintering). By shaking (vibration compaction) an even distribution - particularly important with complex shapes - and first compression of the molding compound can be achieved. With a press stamp (uniaxial pressing) or several press stamps (coaxial pressing) a green body is produced at pressures from a few 100 bar up to 10,000 bar. In contrast to liquids, the pressure does not spread evenly in all directions and the lateral material flow is low; the resulting compaction of the green body decreases due to internal frictional forces and friction with the press mold with increasing distance from the press stamp (s).

To avoid this disadvantage, so-called isostatic pressing is increasingly being used: The molding compound to be pressed - usually dry and powdery - is introduced into a closable elastic mold (e.g. made of polyurethane, silicone or rubber) and usually by shaking (vibration compaction) ) pre-compressed. The mold is now introduced into the so-called recipient (a pressure-tight, closable container) filled with liquid (usually water, oil or oil-water mixtures), more rarely gas, which is closed. By increasing the pressure in the recipient using a hydraulic system (compressors for gas) to a few 100 to a few 1,000 bar, the shape is then isostatically pressed due to the even distribution of pressure in the liquid or the gas, so that the compression does not take place axially, but from the outside inside. Furthermore, the particles to be compressed cover a much shorter distance in isostatic pressing than in axial pressing methods. As a result, the resulting green compact has its highest compression and thus, after sintering, the highest strength on the surface, where it is also used in the finished workpiece, whereby the density distribution and the resulting strength distribution have a much lower gradient than in axial pressing processes . Isostatic pressing is usually done cold (cold isostatic pressing), but can be used when using gases as pressure medium such as argon and elastic Molds made of metal containers (so-called capsules) can also be carried out hot (hot isostatic pressing), in which case pressure sintering is already possible in the latter case. After the isostatic pressing process, the excess pressure of the pressure medium is released and the green body is removed from the elastic form. The further treatment to the sintered end product is carried out in the same way as in the second powder injection molding, with binders being removed by subsequent process steps or being able to remain in the green body in a targeted manner.

Analogous to the processes described above, molds or mold cores made of water-soluble, meltable or burnable substances can also be used in uniaxial, coaxial or isostatic pressing in order to be able to produce workpieces with cavities and undercuts. Depending on the requirements of the pressing process (pressure, temperature), the sintered materials used, the shape of the workpiece, etc., mold cores also come from e.g. low-melting metals, salts, waxes, foamed or compact plastics or other disintegrable materials for use ("Introduction to powder metallurgy; processes and products"; 6th edition, 2010; brochure of the European Powder Metallurgy Association (EPMA), SY2 6LG Shrewsbury, United Kingdom; available from Fachverband Pulvermetallurgie eV, 58093 Hagen, Germany; www.pulvermetallurgie.com).

4. Investment casting

In the investment casting process, lost models of the workpiece are produced from special meltable or water-soluble waxes (e.g. based on polyethylene glycol or polyacrylate) or burn-out thermoplastic materials (e.g. from foamed polyurethane or polystyrene), for example using injection molding technology with aluminum or steel tools. In order to create cavities or undercuts, such a model can additionally be provided with water-soluble, meltable or burnable lost cores. The model is then dipped in so-called slip, a ceramic mass for the production of a molded shell, consisting of a refractory, fine powder and a binder, for example ethyl silicate. The model wetted with slip is then sprinkled with sand and dried. Diving and sanding are repeated until the fireproof molded shell has reached the required stability. Water-soluble cores are now removed in a water bath, meltable cores are removed by thermal treatment, for example with steam. The molded shells are now fired at approx. 750 - 1200 ° C, whereby burnable cores or core residues are completely removed. Then the actual metal casting (e.g. steels and alloys based on iron, aluminum, nickel, cobalt, titanium, copper, magnesium or zirconium) takes place in the ceramic molded shell and reworking the cooled workpiece. The castings obtained in this way are characterized by their level of detail, dimensional accuracy and surface quality. Investment casting tends to serve niche markets in the high-performance segment with smaller quantities ("Investment casting: production, properties, application"; brochure Bundesverband der Deutschen Gießerei-Industrie, 2015, www.kug.bdguss.de; Giessereilexikon. 19th edition, Stephan Hasse, 2007; Verlag Schiele and Schön, ISBN 978-3794907533).

5. Laminating fiber-plastic composites

Modern fiber-plastic composites consist of a matrix (e.g. from thermosets such as synthetic resins, more rarely from thermoplastics) and several layers of fiber fabrics, scrims, knitted fabrics, mats, tiles etc. with different main fiber directions. Particularly tear-resistant fibers are used, e.g. Glass fibers, carbon fibers (carbon fibers), ceramic fibers, polyaramid fibers, steel fibers, polyamide fibers, polyester fibers, cellulose fibers, etc. In the hand-laminating technique, the fibers are placed on a shaped body and impregnated with the not yet hardened / solidified matrix. The layer is compressed, deaerated and excess matrix removed by pressing with a roller. This process is repeated layer by layer until the desired material thickness is reached. The workpiece is then cured thermally at normal pressure or in a vacuum until the matrix material has cured. Other automatable lamination processes are resin transfer molding (RTM), high pressure resin transfer molding (HD-RTM) and structural reaction injection molding (SRIM).

Here too, lost shapes are used for complex workpiece geometries with cavities and undercuts. An example of this are CFRP mountain bike handlebars, which use the CAVUS project procedure (see http://www.polyurethanes.basf.de/pu/solutions/de/content/group/innovation/concepts/Cavus and http: //www.ktm-technologies.com/projekte/cavus): lost molds and cores made from sand-binder mixtures are used here to be able to produce the extremely light but high-strength, complex-shaped and internally hollow mountain bike handlebars. The lost mandrel is covered with a carbon fiber knitted tube and processed to the finished workpiece in a few minutes at 200 bar in an HD-RTM process. The lost core is then removed in a water bath, dissolving the water-soluble binder. Depending on the process (1-5), lost molds are formed in the prior art from metals or alloys with low melting temperatures, from thermoplastic materials or from waxes. These materials per se or in their processing have a number of disadvantages:

Melting alloys such as Wood's metal, Roses metal etc. are reusable to a limited extent, but are toxic due to the heavy metals they contain, such as lead and cadmium. The relatively high density makes handling particularly difficult with large mold core volumes due to the high weight. Modern, heavy metal-free melting alloys e.g. based on indium, bismuth and tin are not toxic, but their price is significantly higher in the order of magnitude.

Table 1: Properties of melting metals and alloys

Sources: http://www.matweb.com; Journal of Biomechanical Engineering, 2006, 128, 161; https: //www.azom. com / properties. aspx? ArticleID = 590;

Properties of Lead-Free Solders, NIST Database Release 4.0, 2002:

https://www.msed.nist.gov/solder/NIST_LeadfireeSolder_v4.pdf Table 1 shows the mechanical properties of such melt alloys and some of their alloy components. The pure metals lead, tin and indium are i as core materials because of their softness i. A. Not suitable, pure indium is far too expensive. Pure bismuth is significantly harder and therefore suitable for mold cores, but, as already mentioned, also relatively expensive; it is also relatively brittle and can break relatively easily. The melting alloys listed show relatively good hardness, but are either toxic (alloy components Pb, Cd) or very expensive (alloy components In). Bismuth-tin alloys seem to be relatively well suited (hardness, tensile strength, toxicity), but are also in the price range of 100 - 200 euros / L. In addition to lead and cadmium, indium and bismuth are also classified as "Hazardous waste according to the Ordinance on Waste Catalogs (AVV)" (http://gestis.itrust.de) according to the GESTIS database of the German Institute for Occupational Safety and Health, and thus generate disposal costs . As is known to the person skilled in the art, melts of the metal alloys mentioned show maximum viscosities of a few mPa s, which, when the lost molds or mold cores are melted out, together with the high density, makes it easy to drain from cavities with narrow cross sections. Nevertheless, it can be expected that metallic residues cannot be avoided, which can lead to problematic metal and metal oxide vapors (especially in the case of alloys containing heavy metals) and also the end product at the required more or less high temperatures of the various shaping processes in processing strain.

Compared to the aforementioned metals, lost molds and mold cores made of, for example, thermoplastic materials are orders of magnitude cheaper, so that, in contrast to metals, one-time use can be economical. The density of suitable plastics is in the range of approx. 0.9 to 1.2 g / cm ³ (see table 2) and thus significantly lower than that of metal alloys, which makes handling large mold cores easier.

Table 2: Properties (guide values) of selected plastics

Sources: https://www.kern.de/de/richtwerttabelle

Tensile strengths of plastics tend to be higher than those of metal alloys, the modulus of elasticity shows a much better elasticity with values lower by two powers of ten, which, on the one hand, leads to higher mechanical stability of the lost mold core when anisotropic pressure conditions are used when molding a molded part in the processes described above (less easy tearing of structures due to shear forces), but on the other hand it can lead to larger deviations from the target geometry of the workpiece. In contrast to metallic lost mold cores, it is not possible to simply melt and drain them to remove them from the workpiece, since the naturally high viscosities of plastic melts (high molecular weights) with approx. 100 to a few 1000 Pa · s are 5-6 powers of ten above those of metals described above (plastic paperback; Oberbach, Saechtling, 28th edition, Hanser Munich 2001, ISBN 978-3-446-21605-1). In order to be able to remove plastic cores completely, they must either a.) Be soluble in a solvent or b.) Completely decompose into gaseous components at high temperatures (protective gas, e.g. necessary when sintering carbon-containing ceramics or carbides; often does not succeed , because charring takes place) or burned (air). In order for the dissolving of water-soluble plastics or other plastics in organic solvents to be economical, this must take place quickly enough and the disposal costs or reprocessing costs of the resulting solution must be within acceptable limits. As the solutions of plastic polymers also have high viscosities, the dissolving process is, as expected, relatively slow, especially when it can no longer be accelerated by mechanically generated turbulent flow or thermally generated turbulent convection. This also applies if the material has to make several changes of direction when it is released and released from the cavity. In the case of cavity or undercut structures of the tool to be produced, which are, for example, deeply located, that is, one have a large distance to the surface or very small cross sections, the dissolution process is more and more diffusion controlled and therefore slower and slower.

The thermal decomposition or burning of plastic mold cores is only successful if the workpiece can withstand the necessary temperature, duration and atmosphere (oxidative, inert, reductive). During the decomposition process itself, large quantities of hot gases are naturally generated, which must be able to escape freely from the cavities or undercuts of the workpiece, since otherwise the pressure generated can damage or destroy the workpiece. Due to the high viscosity of the polymer melt that arises before thermal decomposition, problems can arise in narrow and / or angled or complex, communicating cavity or undercut structures of the tool to be produced if the escape of the gases is made difficult by blocking, still molten areas or is prevented.

In principle, the thermal removal of the lost plastic mold cores requires the post-treatment of the resulting decomposition gases, which usually contain toxic components (e.g. NOx in polyurethanes, polycyclic aromatics, monomers, etc.).

Molded cores made of water-soluble waxes (e.g. based on polyethylene glycol) or water-insoluble waxes (e.g. paraffins) can only be used to a very limited extent at low pressures, e.g. in investment casting.

It is therefore the task of providing a composition which overcomes the disadvantages described above and can be used as a lost form in various processes. This means that a shape can be produced from the composition that has both good mechanical stability and at the same time best removability.

BRIEF DESCRIPTION OF THE INVENTION

The object is achieved by a mold composition comprising

- At least one sugar component in a weight fraction of at least 20%, preferably at least 50%, particularly preferably at least 80%, based on the weight of the molding composition and

- at least one aggregate. The object is also achieved by a mold for a molding process, the mold being a compact three-dimensional structure made up of the mold composition according to the invention. This means that a mold composition according to the invention can be used as such (without further additives) to produce a mold.

In a further aspect, the invention relates to a method for shaping a workpiece, comprising the steps

Providing at least one form,

Contacting the mold with a material to be molded,

- hardening of the material to be shaped in order to obtain the workpiece,

- removing the shape from the workpiece,

characterized in that the at least one shape is a shape according to the invention, ie is a compact three-dimensional structure made up of a shape composition according to the invention.

The molding composition according to the invention comprises a sugar component as an essential component, preferably in terms of quantity as the main component.

The sugar component is understood to mean a mono-, di- or oligosaccharide (sugar / saccharides) or a sugar alcohol derived from such a saccharide, a hydrate of a sugar or a sugar alcohol or a mixture thereof. Sugar and sugar alcohols have long been known, extremely inexpensive, non-toxic and readily available substances, which are widely used in the field of food production as sweeteners or in the production of pharmaceutical preparations as e.g. find tablettable matrices or other excipients ("Pharmaceutical excipients"; Schmidt, Lang, 2013, Govi-Verlag Pharmaceutischer Verlag GmbH, Eschborn, ISBN 978-3-7741-1298-8).

It has now been found that a composition comprising a sugar component can be provided as a compact three-dimensional structure and as such is suitable as a mold for various molding processes, for example in the process according to the invention for molding a workpiece. Due to the glass-like surface, low porosity, high strength, low density and good formability, molds made from the mold composition according to the invention have proven to be suitable for transferring a three-dimensional contour when the mold comes into contact with a material to be molded, for example in the production of ceramic workpieces . The shapes can be used in particular for imaging internal areas such as undercuts and cavities because they are easily melted out by the sugar component, burned out or soluble with hydrophilic solvents such as water. The shape is therefore preferably used as a lost shape. The sugar components are also very inexpensive, readily available, non-toxic and easy to dispose of (commercial waste, sewage treatment plant).

The structure of the mold is achieved if the mold composition is provided as a (cooled) melt or a compressed material. The mold composition can be shaped by melting the sugar component, mixing with the additive (or vice versa) and pouring the mold composition, e.g. by casting in appropriate silicone molds to obtain mechanically stable molds after cooling. Other methods that are conceivable include injection molding, 3D printing or direct pressing without melting. These processes are known in food production (e.g. hard caramels) or in the pharmaceutical industry.

The mold composition according to the invention and the mold according to the invention further comprise at least one additive.

The additive has the surprising effect that the mold from the mold composition has an even higher mechanical strength. In particular, the fracture formation and fracture continuation in a structure made from the sugar component could be reduced by adding a relatively small amount of an additive without impairing the formability or other advantageous properties compared to a shape consisting only of a sugar component.

DETAILED DESCRIPTION OF THE INVENTION

According to the invention, the term sugar component is to be understood as meaning a mono-, di- or oligosaccharide (synonymously also sugar or saccharide), a sugar alcohol derived from such a saccharide, a hydrate of such a saccharide or a sugar alcohol or a mixture thereof. These compounds can be summarized as a subgroup of carbohydrates, the generic name of which includes both saccharides and the sugar alcohols (alditols) derived from reduction of the carbonyl group (IUPAC. Compendium of Chemical Terminology, 2nd ed. (The "Gold Book"). Compiled by AD McNaught and A. Wilkinson, Blackwell Scientific Publications, Oxford (1997), XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nie, J. Jirat, B. Kosata ; Updates compiled by A. Jenkins. ISBN 0-9678550-9-8. "Carbohydrates"; doi: 10.1351 / goldbook.C00820). The prefix oligo denotes compounds that lie between dimers and higher polymers. Typically, oligomeric structures have 3 to 10 repeat units (IUPAC. Compendium of Chemical Terminology, 2nd ed. (The "Gold Book"). Compiled by AD McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997). XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nie, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8., "oligo" doi: 10.1351 / goldbook.O04282) and also here the term oligosaccharide is intended to include carbohydrates from 3 to 10 saccharide units. The sugar component can therefore have 1-10 saccharide units.

The sugars or sugar alcohols can be used as a compound of the general formula I.

C (n * a) H (n * a * 2) + 2b-2c 0 (n * a) -c (I), wherein

n is 1 to 10, preferably 1 or 2,

a is 4, 5 or 6,

b is 0 or 1, and

c is n-1 or n,

describe.

In monosaccharides or sugar alcohol derived from monosaccharides, n is 1, while in disaccharides or sugar alcohols derived from disaccharides n is 2. In oligosaccharides, depending on the number of repeat units, n is 3-10.

Variants include four carbon atoms (tetrose), five carbon atoms (pentose) and six carbon atoms (hexose), so a can be 4, 5 or 6, preferably 4 or 6, even more preferred 6. While the term sugar component also includes mixed di- and oligosaccharides with regard to the number of carbon atoms of the individual repeating units, formula I is only to be applied to the sugar components in which the repeating units have the same number of carbon atoms.

In di- and oligosaccharides, one or more water molecules are formally split off by the condensation. For each condensation there are two H and one O less in the sum formula, which is reflected in formula I, because in di- and oligosaccharides n is greater than 1 and thus a value for c greater than or equal to 1 results from c equal to n-1. The formal deduction of an FFO molecule per condensation follows in formula I. Cyclodextrins are a group of oligosaccharides with 6-8 glucose units that are linked a-1,4-glycosidically and form a ring. Another water molecule is split off by the ring formation. In the case of cyclic oligosaccharides, c is therefore n. A - Cyclodextrin with 6 glucose units has the empirical formula C36H60O30, i.e. corresponds to formula I with n = 6, a = 6, b = 0 and c = n = 6.

Sugar alcohols are derived from the respective sugar by reduction, which is formally expressed by two additional hydrogen atoms in the empirical formula. For sugar alcohols in formula I, b is therefore 1, while for sugars, i.e. ketoses or aldoses, b is 0.

In addition, a sugar component can be a hydrate of a saccharide or a sugar alcohol or a compound of the general formula I. Sugars such as glucose occur as anhydrous forms (anhydrates) or as hydrates. The term “hydrate” can mean both a variant that contains crystal water and an organic hydrate in which water is bound by an addition reaction, as can occur, for example, with aldoses. The anhydrous forms of the sugar components or compounds of the formula F are preferred

Likewise, the at least one sugar component can be a mixture of at least two saccharides or sugar alcohols or compounds of general formula I or their hydrates.

Isomalt is a hydrogenated isomaltulose (Palatinose ^® ), which consists of approximately equal parts of 6-OaD-glucopyranosyl-D-glucite (GPS, isomaltitol) and 1-Oad-glucopyranosyl-D-mannitol (GPM). This is a preferred mixture of two sugar alcohols, each derived from a disaccharide.

Mixtures are particularly preferred when the mixture has a low melting point compared to the individual sugar components, i.e. so-called eutectic mixtures.

A mono-, di-, oligosaccharide (saccharide), or a sugar alcohol derived from such a saccharide or a compound of the general formula I can typically be present in various stereoisomers (enantiomers) due to the asymmetrically substituted carbon atoms. From the general designation or all possible enantiomers are included, but the naturally occurring enantiomers are preferred in each case.

In a preferred embodiment, the at least one sugar component is selected from the group consisting of sucrose, D-fructose, D-glucose, D-trehalose, cyclodextrins, erythritol, isomalt, lactitol, maltitol, mannitol, xylitol and mixtures of these.

The at least one sugar component typically has a decomposition temperature range and / or a melting point. The term decomposition temperature range describes a temperature range at which the sugar component softens under chemical decomposition, such as (strong) caramelization. When caramelizing, various reactions also occur between the individual molecules of the sugar component, such as condensation and polymerization and elimination of smaller molecules, so that the original sugar component is decomposed. The end product of the thermal decomposition of a sugar component is CO2 and water under oxidative conditions and carbon under reductive conditions. In practice, there is often no distinction between the decomposition temperature range and the melting point and both values are often given in the literature as mp, for English melting point. The melting point is to be defined here as the temperature range at which the sugar component changes from the solid to the liquid or gel state of aggregate without decomposition. The melting point, as used herein, includes both the transition from a crystalline solid state to a liquid and the transition from a glassy solid state to a liquid (also known as a glass transition temperature). A change in the viscosity of the sugar component therefore occurs at the melting point. Typically, the viscosity drops by at least a power of ten when the sugar component is heated from a temperature below the melting point to a temperature above the melting point.

In a preferred embodiment, the at least one sugar component has a melting point and a decomposition temperature range, the melting point being below the decomposition temperature range.

Many sugars in their anhydrous form decompose strongly below their melting point and caramelize. Sucrose has a real melting point of 185-186 ° C, with decomposition starting at around 160 ° C. D-fructose (mp 106 ° C) or D-glucose (mp 146 ° C) cannot be processed by melting and are therefore considered Sugar component not preferred. The melting points can be reduced by eutectic mixtures with one another to the extent that this problem can be solved, for example sucrose (30% w) - glucose (mp 137 ° C.), sucrose (30% w) - fructose (mp 97 ° C.), glucose (27% w) - Fructose (mp 93.2 ° C) (see J. Appl. Chem., 1967, Vol. 17, 125).

D-trehalose (mp 214-216 ° C) can e.g. melted without caramelizing and only decomposes at 284 ° C; most water-free sugar alcohols such as Erythritol (mp 122 ° C), isomalt (mp 145-150 ° C), lactitol (mp 144-146 ° C), maltitol (mp 148-151 ° C), mannitol (mp 165-168 ° C, Td 300 ° C) or xylitol (mp 93-94.5 ° C) show no thermal decomposition well beyond their melting point and can therefore be processed in accordance with the invention (“Pharmaceutical auxiliaries”; Schmidt, Lang, 2013, Govi-Verlag Pharmaceutischer Verlag GmbH, Eschborn, ISBN 978-3-7741-1298-8).

The particularly preferred sugar components therefore include D-trehalose, isomalt, erythritol, lactitol, mannitol and eutectic mixtures of sucrose and D-glucose.

In a preferred embodiment, the molding composition is not hygroscopic or is hygroscopic only from a relative humidity of the ambient air of 80%.

The hygroscopic properties of the mold composition, i.e. its property of absorbing water from the environment, is mainly determined by the sugar component, but can possibly be influenced by an additive. Some sugars or sugar alcohols are highly hygroscopic, i.e. they already take off at a low relative humidity of the ambient air (RH). This property is mostly described in the literature or the person skilled in the art can determine it using common methods.

Hygroscopic sugar components are often less suitable for the application according to the invention, since the glass transition temperature drops with uncontrolled absorption of water (see https://de.wikipedia.org/wiki/Gordon-Taylor- equation; "Critical water activity of disaccharide / maltodextrin blends"; Sillick, Gregson, Carbohydrate Polymers 79 (2010) 1028-1033) and if the temperature falls below room temperature, the sugar or sugar alcohol changes from a glass to a plastically deformable and rubber-like state. As a result, the properties of a compact three-dimensional structure made from a mold composition containing such sugar components are less suitable for some applications. If the mold has a relatively large surface area, is exposed to moist air for a relatively short time or not at all, and / or if the application permits a tolerance, molding compositions with hygroscopic properties may also be suitable.

D-fructose, D-sorbitol and D-lactose and to a lesser extent D-glucose can be mentioned as examples of strongly hygroscopic sugars or sugar alcohols. Weakly hygroscopic and therefore preferred are e.g. the sugars and sugar alcohols already mentioned, sucrose (from 85% RH), D-trehalose (from 92% RH), maltitol (from 80% RH) and xylitol (from 80% RH). The sugar alcohols erythritol, lactitol, and mannitol are not hygroscopic. Mixtures (e.g. eutectic mixtures) of hygroscopic sugars and / or sugar alcohols with non-hygroscopic sugars and / or sugar alcohols are not hygroscopic per se and can therefore be preferred.

Table 3: Properties for various sugar components

* Melting point or range of decomposition.

¹ Molecules 2008, 73 (8), 1773-1816.

² G. Kumaresan, R. Velraj and S. Iniyan, 2011. Thermal Analysis of D-mannitol for Use as Phase Change Material for Latent Heat Storage. Journal of Applied Sciences, 11: 3044-3048. ³ https://cameochemicals.noaa.gov/chemical/20064X accessed December 2018).

⁴ Römpp Online 4.0, https://roempp.thieme.de (accessed December 2018).

⁵ BJ Donnelly, JC Fruin, and BL Scallet. 1973 Reactions of Oligosaccharides. III. Hygroscopic Properties. Cereal Chem 50: 512-519.

⁶ Peter C. Schmidt, Siegfried Lang, Pharmaceutical auxiliaries 2013: mp 223 ° C (pure anhydrous alpha-lactose), mp 252.2 ° C (pure anhydrous beta-lactose), mp 232.0 ° C

(typical commercial product). In a further embodiment, it is preferred that the molding composition according to the invention further comprises water, preferably water in a weight fraction of at most 10% based on the weight of the molding composition.

In particular when producing the mold from a cooled melt, the addition of small amounts of water to the mold composition already showed a significant improvement in the elastic properties, i.e. compared to the molds from the corresponding mold composition without water, the molds from the water-containing mold composition showed better resistance to impact or breakage after scoring (see Example 2).

Another component of the molding composition according to the invention is the additive. The additive is preferably present in a weight fraction of at most 20%, preferably at most 10%, based on the weight of the molding composition.

For the molding composition according to the invention, the following compositions, inter alia, result for the weight fractions of the three constituents described:

Sugar component: approximately 70% to approximately 99%, preferably approximately 85% to approximately 99%

Aggregate: approximately 1% to approximately 20%, preferably approximately 1% to approximately 10%

Water: 0% to approximately 10%, preferably approximately 0% to approximately 5%

A proportion by weight starting from a value of 0% includes that this component is not included in the composition (0%) or is included (> 0%). The percentages by weight are in each case expressed as a percentage by weight of the total mass of the molding composition (m / m).

An additive can be in powder, fiber or other form, the additive preferably being solid and in pieces, for example as a fiber or powder, at room temperature. The aggregate is preferably used with a fiber length or grain size <5 mm, for example as a fiber of 0.2 mm to 3 mm in length. In such sizes, the aggregate can form well in the mold composition, i.e. uniform, to be distributed. In a preferred embodiment, the at least one additive is powdery or fibrous.

Even in small quantities, the additive has a considerable effect on the mechanical properties of molds from the mold composition according to the invention (see examples 1 C and 1 D). The aggregate prevents, among other things, the susceptibility to break typical of glass-like bodies or to bursting to sudden stress. The exact mechanism of how this effect is achieved remains unclear. Since both crystalline and amorphous areas are to be expected in the structure due to the sugar component, the mechanical properties can vary solely by influencing the distribution or the limits of these areas.

The inventors have tested various materials and shapes for the aggregate and the benefits are evident for a wide range of materials and shapes (Example 1 C-D).

In general, the inventors are expected to find that such materials, which are solid, have good mechanical properties (high compressive and / or tensile strength) and that they interact with the sugar component, such as electrostatic interactions (e.g. ion-dipole interactions) ) and / or hydrogen bonds, but also weak interactions such as Van der Waals interactions and hydrophobic interactions.

It is preferred that the additive is not soluble in the sugar component or is not dissolved during the manufacture of the mold. The mold composition is therefore preferably a heterogeneous mixture, the additive being selected such that it can be uniformly distributed in the sugar component or in the melt of the sugar component.

Both lipophilic materials such as carbon or polyethylene and hydrophilic materials such as cellulose are suitable as additives. In contrast, materials that are both hydrophobic and lipophobic, such as perfluorinated polymers (e.g. polytetrafluoroethylene and polyvinylidene fluoride), have proven to be less suitable. For such materials, no or hardly any interactions with a sugar component are to be expected. For example, the wetting angle between the material of the additive and the liquefied sugar component can be seen as a relevant criterion, which is preferably less than 160 °, more preferably less than 120 °.

It is also preferred that the aggregate has good thermal stability. In one embodiment, the aggregate has a melting point or thermal decomposition point that is higher than that of the sugar component, which means that the Aggregate is solid even during the manufacture of a mold by means of melting and does not decompose thermally.

Suitable materials for the aggregate can be those which the person skilled in the art, for example, as a filler and / or reinforcing material in connection with plastics (for example described in DIN EN ISO 1043-2: 2012-03 plastics part 2: fillers and reinforcing materials) or as a fiber material in Fiber composites (e.g. described in https://de.wikipedia.org/wiki/Faserverbundwerkstoff) as fiber-plastic composite (e.g. described in https://de.wikipedia.org/wiki/Faser-Kunststoff-Verbund) are known.

Known fillers and reinforcing materials are selected, for example, from the group consisting of aramid, boron, carbon (crystalline, partially crystalline or amorphous, for example carbon fiber, graphite, carbon black, activated carbon, graphene), aluminum hydroxide, aluminum oxide, clay, glass, calcium carbonate, cellulose, metals, Mineral, organic natural substances such as cotton, sisal, hemp, flax etc., mica, silicate, synthetic organic substances (e.g. polyethylene, polyimide), thermosets, talc, wood, chalk, sand, diatomaceous earth, zinc oxide, titanium dioxide, zirconium dioxide, quartz, starch .

Known fibrous additives are selected, for example, from the group consisting of inorganic reinforcing fibers (such as basalt fibers, boron fibers, glass fibers, ceramic fibers, quartz fibers, silica fibers), metallic reinforcing fibers (eg steel fibers), organic reinforcing fibers (eg aramid fibers, carbon fibers, PBO fibers, Polyester fibers, nylon fibers, polyethylene fibers, polymethyl methacrylate fibers), and natural fibers (e.g. flax fibers, hemp fibers, wood fibers, sisal fibers, cotton fibers and products made from these fibers, which have been modified by chemical and / or physical treatment ).

Preferably, only one additive is used in the molding composition according to the invention, i. H. a material in a form (e.g. powder or fiber). However, it is not excluded that the mold composition comprises several additives, for example additives made of different materials and / or in different forms.

In a preferred embodiment, the at least one additive is selected from the group consisting of cellulose, carbon, glass, aramid, aluminum oxide, Silicon dioxide and polyethylene, preferably cellulose and carbon, more preferably glass, cellulose and carbon fibers.

The mold according to the invention, which is suitable for use in a molding process, is a compact three-dimensional structure made from the mold composition according to the invention. The term compact three-dimensional structure is intended to express that the form forms a dimensionally stable body of a specific shape / geometry. This body is preferably formed uniformly, uniformly from the molding composition.

In the mold according to the invention, the heterogeneous character of the mold composition can also be recognized macroscopically or under the light microscope. In one embodiment, it is a heterogeneous (two-phase) structure in which the additive is present as a disperse phase in the sugar component (as a continuous phase or matrix).

For the mold according to the invention, which is a structure of the mold composition according to the invention, parts by weight are to be expected which correspond to those of the mold composition. Naturally, fluctuations between composition and shape can occur. For example, the proportion of water in the manufacture of the mold can decrease due to the evaporation of water compared to the mold composition and thus be lower in the mold.

In order to obtain a structure, the components of the molding composition are provided, mixed and molded into a three-dimensional body. The final step in this method of making the mold can be achieved at least in two different ways.

The mold composition is preferably introduced as a melt into a further three-dimensional casting mold, which is a negative of the three-dimensional body, which the shape according to the invention is to take, and is cooled. The melt is achieved by heating the mold composition to a temperature in the region of the melting point, preferably above the melting point, of the sugar component. The liquefied mold composition can then be molded by casting. Suitable molds for molding the melt are, for example, silicone molds, which due to their elasticity can also be removed from complex three-dimensional structures as soon as they have cooled and are therefore firm. In this case, the structure is a cooled melt. Cooled melts of a sugar component are also called sugar glass. Such methods for producing three-dimensional structures from cooled melts are known for example from food production (for example with hard caramels or sugar decorations) and, as shown here, can be used not only for sugar components but also for mold compositions which also contain an additive.

Further modifications in which a structure consisting of a melt is produced from the mold composition by means of injection molding or 3 pressure are conceivable for the person skilled in the art.

Alternatively, the mold composition can also be pressed into a three-dimensional structure. For example, it is known from the pharmaceutical industry that sugar components can be molded into compact three-dimensional structures by means of pressure. In this case, the structure is compressed. For the cohesion in the compressed or the compact, cohesive, adhesive forces, solid bridges or form-fitting bonds come into consideration (Bauer KH, Frömming K.-H., Führer C. Pharmaceutical Technology, 5th edition, 1997, Gustav Fischer Verlag, page 332 "Binding in tablets"). The production of the mold by means of pressing will be preferred especially for molds which have a relatively simple three-dimensional shape.

In a preferred embodiment, for the mold according to the invention and also for the process for molding a workpiece, the structure is a melt or a compact of the molding composition.

The method according to the invention for shaping a workpiece, comprising the steps

Providing at least one form according to the invention,

Contacting the mold with a material to be molded,

- hardening of the material to be shaped in order to obtain the workpiece,

- Remove the shape from the workpiece.

In one embodiment, the method of forming a workpiece in the frame

1. a melt core injection molding process,

2. a powder injection molding process,

3. a pressing process,

4. a production of a fiber-plastic composite material by means of laminators or

5. a production of a ceramic molded shell for the investment casting

be used. The types of molding processes (1-5) described above are known in principle. The mold according to the invention, which is a compact three-dimensional structure comprising the mold composition according to the invention, can replace the known molds, in particular the known lost molds, in these processes. Embodiments with regard to the workpieces, the materials to be molded, hardness steps or possible post-treatments thus result in part from the prior art.

The material to be molded is preferably provided in a flowable, free-flowing or at least plastically deformable state for contacting the mold or, if appropriate, a plurality of molds, so that when the mold contacts, a positive fit between the material and the mold is achieved and the three-dimensional configuration of the mold during hardening of the material is transferred.

In the method according to the invention, the hardening step is seen as the step in which the mold according to the invention permanently transfers its contour to the material to be molded. In preferred embodiments, such as in pressing and also in powder injection molding, additional steps for further processing of the initially obtained workpiece (green body) can also be provided, which can (also) be referred to as hardening steps, but are to be distinguished from the hardening step according to the invention.

The material can be hardened in different ways depending on the type of molding process. The hardening is preferably carried out mechanically or mechanically-thermally.

In this embodiment, the hardening is preferably carried out by exerting pressure on an arrangement of mold (s) and material to be molded, which arises when the mold contacts the material, as is the case, for example, in the course of a pressing process, in particular an isostatic pressing process. When hardening by pressure, the advantageous mechanical properties of the mold composition are particularly effective.

In molding processes such as melt-core injection molding, powder injection molding or processes for the production of fiber-plastic composites by means of lamination, the material to be molded (polymer mass, feedstock or layered matrix material) is often provided at an elevated temperature so that it contacts the mold in the plastic state becomes. The hardening is then also carried out by cooling (ie mechanical-thermal). In the case of thermal hardening, the person skilled in the art will note that preference is given to using those molds according to the invention in which Sugar component has a decomposition temperature range and / or a melting point that is not significantly lower than the temperatures used during contact with the material.

In a preferred embodiment of the method according to the invention, the structure of the mold is destroyed when the mold is removed.

In this embodiment, the at least one mold according to the invention, which is a compact three-dimensional structure comprising a mold composition according to the invention, is a so-called lost mold. At least it loses its three-dimensional design, shape or geometry), i.e. the structure after it has been transferred to the material. Optionally, the components of the mold composition are broken down when destroyed. The at least one form of the process can be removed by various process steps due to the sugar component, which is an essential or the main component of the mold composition.

The shape can preferably be removed by

Dissolving the mold composition with a hydrophilic solvent, preferably water,

Melting the sugar component by heating and, if appropriate, pouring off the mold composition,

Decompose the sugar component by heating and, if necessary, shaking out the

Mold composition (gasification),

or a combination of these measures.

In all cases, the structure of the mold is destroyed and the mold composition can be removed with the additive. Solving and melting are preferred, in which the mold is removed in the liquid state. Solving is preferred with workpieces that are thermally sensitive, since no elevated temperatures have to be used here. On the other hand, removal of the mold by melting can be advantageous if the further processing of the workpiece already provides for thermal treatment. In the case of ceramic and metal workpieces, after the initial hardening, that is to say the production of a green compact, a further thermal hardening step is often provided (sintering), which in the method according to the invention can be accompanied by the removal of the shape from the workpiece. The decomposition of the sugar component usually requires a higher temperature compared to melting and is therefore less preferred, but can be used well to remove possible residues which have not yet been completely removed by melting. During decomposition, the mold composition is at least partially removed in the gaseous state, ie it is also possible to remove it from cavities that are particularly difficult to access.

In the method according to the invention, the at least one shape according to the invention is preferably used as an internal shape. An internal shape is also referred to as a mold core or support structure and forms the inner product geometry of a workpiece to be molded.

In this embodiment, an outer shape can also be used, which preferably consists of a different material than the shape according to the invention. The outer shape can also be formed in several parts, for example a split permanent shape. In carrying out the method in which a further mold is used, an arrangement is formed when the molds come into contact with the material, in which a large part, preferably more than 80%, of the entire outer surface of the mold is in contact with the material to be molded . The shape according to the invention is therefore at least partially enclosed by the material when it comes into contact with the material. It forms a model of a cavity in the workpiece to be molded, while an additional external shape represents a negative external model of the workpiece to be molded.

Experiments are shown below which illustrate compositions according to the invention and / or are helpful for understanding the invention. It goes without saying that the design variants are exemplary.

The figures show stages of a method for forming a workpiece, showing in detail

1 shows two forms, namely an inner form and an outer form in a side view, FIG. 2 in cross section the contacting of the forms with a material to be shaped before hardening (A), after hardening (B) and removal of the outer form, and after the post-curing (C) and the complete removal of the mold from the workpiece (D), and Fig. 3 shows the molded workpiece in side view.

Example 1 - Production and characterization of shapes

A. Production of molds (test bars)

Two different types of sugar were used for the test measurements. On the one hand, commercially available isomalt ("Isomalt ST-M", Beneo GmbH) and on the other a mixture of sucrose ("Wiener Feinkristallzucker", Agrana Zucker GmbH) and glucose ("Dextropur", Dextro Energy GmbH & Co. KG) was used.

Isomalt ST-M contains approx. 2.5% wt water and was melted at 155 ° C overnight in closed aluminum containers in order to keep the water content constant during the melting process. The sucrose / glucose mixture was mixed with water in a ratio of 62% wt sucrose, 14% wt glucose and 24% wt water (known as "sugar boiling"). The sugar mixture was heated up to a temperature of 150 ° C. in a beaker (1000 ml, lower form) on a heatable laboratory magnetic stirrer with vigorous stirring (considerable amounts of water evaporate) and then the melt obtained was immediately further processed. The melt thus obtained typically contains 2-3% wt water.

On the basis of these two sugar melts ("Isomalt ST-M" and sucrose / glucose), test bars measuring 4.7 cm x 2.5 cm x 1.0 cm (haptic tests) and 7.0 cm x 3 were subsequently produced , 8 cm x 3.5 cm (measurement of strength and V modulus), using commercially available silicone molds as the negative mold.

B. Characterization of forms without aggregate

It was found that Isomalt ST-M in particular was very brittle after pouring and cooling, so that the test specimens obviously had very high strength (breaking by hand not possible), but after scratching or punctiform damage to the surface with a sharp object, the test specimen could Test specimens are broken very easily; furthermore, the test specimen burst into numerous pieces after a short, quick blow with a hard object (e.g. with a screwdriver) such as glass. It was also observed that test specimens made from Isomalt ST-M showed very strong scattering with regard to the properties described, which could indicate thermal stresses.

Therefore, attempts have now been made to remove these tensions by annealing. For this purpose, the test specimens produced were cooled once under ambient conditions (room temperature), once kept at 40 ° C (24 h) and once cured in the refrigerator (4 ° C, 24 h) to make the differences clear. The hardness of the differently produced test specimens was evaluated haptically (breaking by hand, scratching the surface and breaking by hand, quick impact). However, tempering the test specimens obviously had no positive influence on hardness and brittleness and the scatter of these properties of the test specimens examined. In a further test series, Isomalt ST-M was melted in a closed vessel and mixed with water in order to obtain water contents of 5% wt and 10% wt. In addition, Isomalt ST-M was melted in an open vessel to obtain a water content of 0% wt. Test specimens were produced with the different Isomalt ST-M types (0, 2.5, 5, 10% wt water), which were then haptically assessed for their hardness. The test specimens with the higher water contents (5% wt or 10% wt) were significantly softer than standard Isomalt ST-M, obviously no longer brittle, but unfortunately not strong enough either, because they could be deformed or broken relatively easily by hand . The test specimens without water were extremely susceptible to impact or mechanical stress, which suggests increased brittleness.

In another, analog test series with a sucrose / glucose mixture, the same effect or trend as with Isomalt ST-M was observed.

Furthermore, when working and storing test specimens made from isomalt ST-M versus sucrose / glucose mixtures, clear differences were found with regard to hygroscopicity: While the former showed negligible tendency to absorb water, sucrose / glucose test specimens were exposed after contact with the open one In the atmosphere, a sticky consistency was observed within a short time, which led to progressive plasticization of the surface of the test bodies within hours, so that they became unusable. In practice, forms made from sucrose / glucose would have to be processed immediately or packaged airtight for storage, especially if the air humidity is high.

C. Haptic description of molds from mold composition with aggregate

In a series of experiments, the various additives (Table 4) with isomalt ST-M and sucrose-glucose (as described above) were examined as a matrix (sugar component).

Table 4: Investigated aggregates

¹ Ordered via Sigma-Aldrich, Inc.

To produce the molding composition, an appropriate amount of Isomalt ST-M was melted as described above, provided with the appropriate amount of additive and carefully distributed uniformly in a beaker with a glass rod. The amount of the aggregate was max. 10% wt. limited, but some additives could only be distributed evenly in the sugar matrix in small amounts.

To prevent premature curing of the material, the mixture was quickly poured into appropriate silicone molds and small test bars (4.7 cm x 2.5 cm x 1 cm). The mechanical properties of the test bars were evaluated haptically in analogy to the method described above (breaking by hand, scratching the surface and breaking by hand, quick blow) and compared with the properties of the corresponding form from the sugar component alone (Table 5). Table 5. Results of the haptic-mechanical testing of sugar bars with various additives.

D. Mechanical description of molds with aggregate

Larger test bars (7.0 cm x 3.8 cm x 3.5 cm) were produced by some candidates who performed better in the haptic tests compared to the non-additive sugar matrix. Of these, compressive strength, flexural strength and V-modulus were measured. A test system from Form & Test Prüfsysteme (www.formtest.de) was used to determine the compressive strengths. Model: DigiMaxx C-20, max. Piston stroke 15 mm, max. Force 600 kN and feed pressure 1 MPa / s according to DIN EN 993-5 (1998). Test bars with the following dimensions were cast for the measurements: 7 cm × 3.8 cm × 3.5 cm. A bending strength machine from Messphysik (www.messphysik.com, Model Midi 5) with a measuring cell up to 500 kN was used to determine the bending strength or the V-module. Here a feed pressure of 0.15 MPa / s was used (according to DIN EN 993-6, 1995). The V-module (also the deformability module) is related to the E-module and, like the E-module, is the first derivative of the stress after expansion or deformation. The V-modulus is determined by creating a regression line in the area of the curve at e _ßr / 2, where 8 _{ßr is} the deformation that occurs when breaking.

The results of the corresponding measurements are shown in Table 6 below:

Table 6. Results for compressive or flexural strength and V-modulus (± standard deviation absolute and relative) for different mold compositions (measured as bars)

4-fold determinations, Isomalt ST-M 10-fold determination It was observed that compared to the pure sugar component - but also compared to a mold composition made up of sugar component and water - the compressive strength is increased for all the aggregate or sugar components examined. The molding compositions according to the invention are therefore more suitable for processes in which a high compressive strength is required.

For isomalt molds, the bending strength shows very high scatter, which indicates mechanical stresses within the mold. The aggregates do not have a quantitative effect on the bending strength for all materials, but it was found that the scatter between different measurements was reduced. The better reproducibility of the flexural strength represents an optimization of the mechanical properties of the molds compared to those without additives. For some mold compositions (with cellulose and pulverized carbon fibers), flexural strengths are achieved that are comparable in size to the tensile strengths of metallic melt alloys (see Table 1).

The addition of an additive shows different effects on the V-module depending on the sugar component. For isomalt, the V-modulus tends to decrease, i.e. that the elasticity is increased, but in particular a reduction in the scatter is also achieved here. For sucrose / glucose, the additive (10 wt% cellulose) has an opposite effect. In both cases, however, the V modulus achieved with aggregate is of the order of magnitude of the modulus of elasticity that is specified for plastics that are used as lost forms (see Table 2).

Example 2 - Process for forming a ceramic workpiece

Technical ceramics are often manufactured using isostatic presses (see also point 3 above).

The mold according to the invention was used in such a method as an internal mold within the ceramic compact, which is to be described in more detail here with reference to the figures.

First (FIG. 1), a mold 1 according to the invention as described in Example 1 was produced from a mold composition with isomalt STM as the sugar component and carbon fiber (ground carbon fiber) as an additive by means of melting and casting in a silicone mold. The mold composition was brought to 160 ° C. in a controlled manner (5 hours), stirred with a simple laboratory mixer and poured into a new silicone mold (20th x 15x 120mm). After the melt has cooled, a high-strength and rigid cast is produced, ie the ingot-shaped mold 1. In addition, an outer rubber mold 2 has been provided in which the mold according to the invention is arranged in the center.

In the second step (FIG. 2A), a ceramic granulate 3 was filled into the outer mold as the material to be molded, so that an arrangement according to FIG. 2B resulted. The outer shape is filled up to the edge. The ceramic granulate was based on alumina graphite with a resin binder.

The rubber mold is closed with a mutual rubber mold and wrapped in a waterproof film. Then the arrangement was pressed using water pressure of 360 bar.

The rubber mold 2 could easily be removed due to its flexibility. The ceramic mass 3 encloses the mold 1 after the pressing process without any visible deformation of the mold (FIG. 2B)

In order to remove the mold 2, the arrangement is heated to 240 ° C. in a hardening furnace, the mold composition 4 incompletely flowing out of the workpiece 3 to be molded, with loss of the mold 2. The residues can be dissolved in the water or only after the subsequent fire.

After curing, the fire follows where the product is heated to 1000 ° C under reducing conditions. Most of the residues evaporate and only small amounts of ash remain in product 5 (FIG. 2D). These can be easily removed using a water jet.

The final product 5 (see also FIG. 3) can have differently complex internal geometries through this technology. The slight shrinkage of the resulting cavity is due to the shrinkage of the ceramic material used and not due to the deformation of the meltable tool. Therefore, the shrinkage can be taken into account when planning the final geometry in order to achieve precise geometry.

Claims

Expectations 1. Comprising mold composition - At least one sugar component in a weight fraction of at least 20%, preferably at least 50%, particularly preferably at least 80%, based on the weight of the molding composition and - at least one aggregate. 2. The molding composition according to claim 1, wherein the at least one Sugar component is selected from the group consisting of monosaccharides, disaccharides, oligosaccharides, sugar alcohols derived from a monosaccharide, a disaccharide or an oligosaccharide, hydrates thereof and mixtures thereof. 3. A molding composition according to claim 1, wherein the at least one Sugar component is a compound of general formula I. C (n * a) H (n * a * 2) + 2b-2c 0 (n * a) -c (I), wherein n is 1 to 10, preferably 1 or 2, a is 4, 5 or 6, b is 0 or 1, and c is n-1 or n, is a hydrate of a compound of general formula I, or a mixture of at least two compounds of general formula I and / or their hydrates. 4. Molding composition according to one of claims 1 to 3, wherein the at least one sugar component is selected from the group consisting of sucrose, D-fructose, D-glucose, D-trehalose, cyclodextrins, erythritol, isomalt, lactitol, maltitol, mannitol, xylitol and mixtures of these, particularly preferably D-trehalose, isomalt, erythritol, lactitol, mannitol and eutectic mixtures of sucrose and D-glucose. 5. The molding composition according to claim 1, wherein the at least one sugar component has a melting point and a decomposition temperature range, the melting point being below the decomposition temperature range. 6. Molding composition according to one of claims 1 to 5, wherein the Molding composition further comprises water, preferably water in a weight fraction of at most 10% based on the weight of the Mold composition. 7. Molding composition according to one of claims 1 to 6, wherein the at least one sugar component is not hygroscopic or is hygroscopic only from a relative humidity of 80%. 8. Molding composition according to one of claims 1 to 7, wherein the at least one additive is present in a weight fraction of at most 20%, preferably at most 10%, based on the weight of the molding composition. 9. Molding composition according to one of claims 1 to 8, wherein the at least one additive is powdery or fibrous. 10. Molding composition according to one of claims 1 to 9, wherein the at least one additive is selected from the group consisting of cellulose, carbon, glass fiber, aramid, aluminum oxide, silicon dioxide and polyethylene, preferably cellulose and carbon. 11. A mold for a molding process, the mold being a compact three-dimensional structure composed of a molding composition according to one of claims 1 to 10. 12. The mold of claim 11, wherein the structure is a melt or a compressed of the mold composition. 13. A mold according to claim 11 or 12, wherein the shape is a heterogeneous structure in which the additive is present as a disperse phase in the sugar component. 14. A method of forming a workpiece comprising the steps Providing at least one mold according to one of claims 11 to 13, Contacting the mold with a material to be molded, - hardening of the material to be shaped in order to obtain the workpiece, - Remove the shape from the workpiece. 15. The method according to claim 14, wherein the structure of the mold is destroyed when removed. 16. The method according to claim 15, wherein the destruction of the structure of the mold is carried out by Melting the sugar component by heating and removing, in particular pouring off, the mold composition, Dissolving the mold composition with a hydrophilic solvent, preferably water, Decompose the sugar component by heating and optionally removing Remnants of the mold composition, or a combination of these measures. 17. The method according to any one of claims 14 to 16, wherein the at least one shape comes to lie within the material to be molded during contacting, and optionally a further shape is contacted from the outside with the material to be molded. 18. The method according to any one of claims 14 to 17, wherein the method for forming a workpiece in the frame - a production of a ceramic molded shell for the investment casting, - a melt core injection molding process, - a powder injection molding process, - a pressing process, or - A production of a fiber-plastic composite material is used by means of lamination. 19. The method according to any one of claims 14 to 17, wherein the hardening to obtain the workpiece is carried out mechanically, preferably by exerting pressure on an arrangement of mold and material to be formed, which arises when the mold contacts the material.