DE102015223008A1 - Mold, process for its preparation and use - Google Patents

Abstract

The invention relates to a mold used for the production of fiber composite bodies or castings from a particulate molding material and a binder, wherein the mold has pores, the pores are filled with a pore filling material, the binder is water-soluble and the pore filling material is liquefiable by increasing the temperature and chemically with respect to the binder is inert. Furthermore, the preparation and the use of the mold are described.

Description

The invention described below relates to the production of fiber composite bodies or castings from plastic serving molds, their preparation and their use. In particular, the invention relates to the production of cavities in fiber composite bodies or castings of plastic serving cores.

In a variety of technical products, components made of plastic or of a fiber composite material (a composite material comprising a matrix of a plastic and a fiber material embedded in the matrix) are used, which have a cavity in their interior. The manufacture of such components is difficult, in particular if the cavity is to have a complex geometry, for example an elongated, curved shape or a shape with undercuts, while at the same time the cavity surface must be smooth and of high quality. One possible way to produce such components in one piece is casting using so-called "lost shapes". In this technique, in a preliminary step, a molded part (the so-called "core") is produced, which corresponds in size and shape to the cavity to be formed. The core is arranged in a casting mold consisting of further molded parts, into which subsequently a liquid polymer material or a liquid polymer precursor is injected. In the manufacture of fiber composites, the core is clad with a fibrous material prior to placement in the casting tool. After casting you get a fiber composite body or a plastic casting with the desired cavity, in which, however, still the core is inserted. This is then removed, which can not be done without destruction of the core due to the mentioned complex geometry of the cavity. The core is "lost" as a molded part.

In order to remove a core from a cavity of complex geometry, it can be crushed, for example, or converted into a liquid or at least flowable state. The prerequisite for this is a suitable condition of the core.

In so-called melt-core injection molding, the core is made from a low-melting metal or a low-melting alloy. The core is placed in a casting tool and molded with plastic. After completion of this step, the resulting casting, including the core contained therein, is transferred to a heating bath to melt the core. For this purpose, the heating bath is adjusted to a temperature which is slightly above the melting point of the low-melting metal or the low-melting alloy, so that the injection-molded part is not damaged. Optionally, the melting time can be shortened by inductive heating of the core metal. Liquid core metal collects at the bottom of the heating bath and can be used to make new cores.

The required low-melting metals or alloys, however, are relatively expensive. In addition, the metals and alloys are limited in the processing of polymers with low processing temperatures such as polypropylene and polyethylene.

Fiber composite components are often fabricated using inflatable tubing that can be placed in place of cores in a casting tool. These are usually closable hoses made of a silicone, which can be subjected to internal pressure during a casting process. After completion of the casting process, the pressure is released and the hose is removed. The hoses used are basically reusable. However, they are thermally and mechanically only limited stability, which sets their reusability in practice narrow limits. Moreover, they are only limitedly suitable for the production of cavities with complex geometries.

From metal casting, it is known to use cores made of sand for the production of cavities in castings. Such cores can also be used in plastic casting, provided that their surface is sealed (for example with a foil). They are made from a molding material mixture comprising a binder and the sand as a particulate molding material. The binder holds the particles of mold base together and thus accounts for the structural integrity of the cores. The cores must be able to withstand the thermal and mechanical stresses occurring during a casting process. After casting, the cores are usually crushed by vibration. When using a water-soluble binder, such as a binder based on magnesium sulfate, water glasses or based on polyphosphate and / or borate, the cores can be solved by the casting process with water from castings obtained.

Such cores are basically also suitable for processing polymers with low processing temperatures. However, the cores often lack the required strength and also the required shelf life. Water-soluble binder materials are often hygroscopic and thus store water in moist environments, which can significantly reduce their binding effect.

It is an object of the present invention to provide for the production of fiber composite bodies or castings from plastic serving molds, in particular for the production of cavities in fiber composite bodies or castings serving plastic cores, which are inexpensive to produce and offer a wide range of applications. In addition, the shapes and cores should have a high strength with high storage stability.

This object is achieved by the form with the features of claim 1 and the method for producing the mold having the features of claim 9. Preferred embodiments of the inventive form are given in the dependent claims 2 to 8. A preferred embodiment of the method according to claim 9 is given in the dependent claim 10. Furthermore, the method with the features of claim 11 of the present invention is also included. Preferred embodiments of this method can be found in the dependent claims 12 to 15. The wording of all claims is hereby incorporated by reference into the content of this description.

The mold according to the invention serves to produce fiber composite bodies or in cast parts made of plastic. In many cases, the mold according to the invention may also be a core for producing cavities. The mold comprises a particulate mold base and a binder and has pores. The binder is a water-soluble binder.

• 1a Sie weist Poren auf und die Poren sind mit einem Porenfüllmaterial befüllt, wobei dieses Porenfüllmaterial durch Temperaturerhöhung verflüssigbar ist.

In particular, the shape is characterized by the following feature:

• 1a It has pores and the pores are filled with a pore filling material, wherein this pore filling material is liquefiable by increasing the temperature.

The pores are at least partially filled with the pore filling material, in preferred embodiments also completely. In embodiments in which the pores are at least partially filled, especially the pores are filled, the openings have towards the surface of the mold.

In other preferred embodiments, the pore filling material not only fills said pores but also covers the surface of the mold.

The pore filling material is preferably chemically inert with respect to the binder and / or with respect to the particulate molding base material. With particular preference it is chemically inert both to the binder and to the particulate molding material. It is further preferred that the pore-filling material is solid at room temperature (20 ° C) and normal pressure (1 bar).

The term "chemically inert" is to be understood in the present case that the pore filling material does not or only to a negligible extent undergoes a reaction, in particular a chemical reaction, during its processing with the binder and / or the molding base material. The pore-filling material is preferably chosen so that it does not weaken the structural integrity of the core in direct contact with the binder and / or pore-filling material. In particular, it must not solve the binder used.

The combination of a porous mold based on a water-soluble binder and a binder to chemically inert pore filling material brings unexpected benefits and opens up applications in the field of plastics processing, which go beyond the possibilities of the aforementioned forms and cores far. In addition, the molds according to the invention are simple and inexpensive to produce.

• 2a Partikel aus anorganischen, wasserunlöslichen Materialien: Zu diesen Materialien zählen insbesondere Sand, Glas, Keramiken, Glaskeramiken, Glasfritten, Silikate wie Aluminiumsilikat, Metalloxide wie Aluminiumoxid, Metallnitride, Titanate, Zirkonate, Aluminate, Carbid, beispielsweise Siliciumcarbid, Metalle, Metalllegierungen, Graphitpartikel, wasserunlösliche oder in Wasser schwerlösliche Salze wie Bariumsulfat oder Calciumcarbonat. Bei den Sandpartikeln handelt es sich bevorzugt um Partikel aus einem feuerfesten, mineralischen Sand. Der Sand kann natürlichen oder synthetischen Ursprungs sein. In Frage kommen insbesondere Quarzsand, Zirkonsand, Chromerzsand, Mullitsand und Olivinsand. Der Begriff „Glaspartikel“ meint vorliegend insbesondere alle Partikel aus anorganischen Gläsern, die sich chemisch inert gegenüber Wasser oder wässrigen Lösungen verhalten, zumindest im Temperaturbereich zwischen 0 °C und 200 °C. Unter keramischen Partikeln sind insbesondere Partikel aus Carbiden, Nitriden, Oxiden, Siliciden sowie aus bekannten Tonmineralien wie zum Beispiel Kaolinit zu verstehen. Mit dem Begriff „Glaskeramiken“ sind Gläser gemeint, die kristalline Teilchen aufweisen, die in eine amorphe Glasphase eingebettet sind. Glasfritten treten als Zwischenprodukte bei der Herstellung von Glasschmelzen auf. Durch oberflächliches Schmelzen eines Glaspulvers backen die einzelnen Partikel des Pulvers zusammen. Bricht man den Schmelzvorgang an diesem Punkt ab, erhält man einen als Glasfritte bezeichneten porösen Körper. Der Begriff „Fritte“ wird auch auf aus diesem Körper durch Mahlen gewonnene Partikel und Pulver angewandt. Als Metallpartikel kommen vorliegend insbesondere Partikel aus Leichtmetallen wie Aluminium in Frage.
• 2b Partikel aus anorganischen, wasserlöslichen Materialien: Zu diesen Materialien zählen insbesondere Salze aus der Gruppe mit Natriumchlorid (NaCl), Kaliumchlorid (KCl) und Natriumcarbonat (Na₂CO₃). Weiterhin zählen auch Nitrate dazu, insbesondere Natriumnitrat (NaNO₃) und Kaliumnitrat (KNO₃).
• 2c Partikel aus organischen, wasserunlöslichen Materialien: Zu diesen Materialien zählen insbesondere wasserunlösliche Polymermaterialien wie Polystyrol, Polyethylen, Polypropylen, Polyurethan und Polycarbonat.
• 2d Partikel aus organischen, wasserlöslichen Materialien: Hierzu zählen insbesondere wasserlösliche Polymere wie Polyvinylalkohol (PVA) oder Salze organischer Säuren, beispielsweise Natriumacetat.
• 2e Partikel aus einem anorganisch-organischen Verbundmaterial: Hierzu zählt beispielsweise Verbundmaterialien aus einem der in 2c oder 2d genannten Polymermaterialien, in das anorganische Partikel, beispielsweise aus einem der unter 2a genannten Materialien, eingebettet sind.

The particulate molding material preferably consists of one of the following components or a combination of at least two of the following components or comprises at least one of the following components or a combination of at least two of the following components:

• 2a particles of inorganic, water-insoluble materials: These materials include in particular sand, glass, ceramics, glass ceramics, glass frits, silicates such as aluminum silicate, metal oxides such as aluminum oxide, metal nitrides, titanates, zirconates, aluminates, carbide, for example silicon carbide, metals, metal alloys, graphite particles, water-insoluble or sparingly soluble in water salts such as barium sulfate or calcium carbonate. The sand particles are preferably particles of a refractory, mineral sand. The sand can be natural or synthetic. In particular quartz sand, zircon sand, chrome ore sand, mullite sand and olivine sand are possible. The term "glass particles" means in the present case in particular all particles of inorganic glasses which are chemically inert to water or aqueous solutions, at least in the temperature range between 0 ° C and 200 ° C. Particles of carbides, nitrides, oxides, silicides and known clay minerals such as, for example, kaolinite are to be understood as meaning ceramic particles. By the term "glass-ceramics" is meant glasses having crystalline particles embedded in an amorphous glass phase. Glass frits occur as intermediates in the production of glass melts. By superficially melting a glass powder, the individual particles of the powder bake together. Canceling the melting process at this point yields a porous body called glass frit. The term "frit" is also applied to particles and powder obtained from this body by milling. In the present case, particular preference is given to particles of light metals, such as aluminum, as metal particles.
• 2b Particles of inorganic, water-soluble materials: These materials include in particular salts from the group with sodium chloride (NaCl), potassium chloride (KCl) and sodium carbonate (Na ₂ CO ₃ ). Also included are nitrates, especially sodium nitrate (NaNO ₃ ) and potassium nitrate (KNO ₃ ).
• 2c Particles of organic, water-insoluble materials: These materials include in particular water-insoluble polymer materials such as polystyrene, polyethylene, polypropylene, polyurethane and polycarbonate.
• 2d particles of organic, water-soluble materials: These include in particular water-soluble polymers such as polyvinyl alcohol (PVA) or salts of organic acids, for example sodium acetate.
• Particles of an Inorganic-Organic Composite Material: These include, for example, composite materials of one of the polymer materials mentioned in 2c or 2d, in which inorganic particles, for example from one of the materials mentioned under 2a, are embedded.

In preferred embodiments, the particles of the particulate molding material may be present as spheres or as hollow spheres. For example, spheres or hollow spheres of glass and of aluminum silicate and of ceramic and glass-ceramic materials are particularly suitable.

The particles of the particulate molding material preferably have an average particle size of <1000 .mu.m, preferably <600 .mu.m. Particularly preferred are particles having average particle sizes in the range of 50 microns to 500 microns.

In some preferred embodiments, the particulate mold base is free of water, preferably also free of water of crystallization, as long as the mold base is a salt.

• 3a Einen wasserlöslichen anorganischen Binder: Hierzu zählen besonders bevorzugt auf Wasserglas basierende Binder, auf Magnesiumsulfat basierende Binder oder auf Phosphat und/oder Borat basierende Binder. Als Wassergläser bezeichnet man sowohl aus einer Schmelze erstarrte, glasartige, wasserlösliche Alkalisilikate, insbesondere Natrium-, Kalium-, und Lithiumsilikate, als auch ihre wässrigen Lösungen. Zur Verwendung im Rahmen der vorliegenden Erfindung eignen sich besonders Natriumwassergläser. Es ist auch möglich, ein Gemisch aus zwei oder mehr verschiedenen Wassergläsern einzusetzen. Ein charakteristisches Merkmal von Wassergläsern ist ihr Modul, worunter man das Molverhältnis SiO₂:M₂O im Wasserglas versteht, wobei M bevorzugt ausgewählt ist aus Li⁺, K⁺ oder Na⁺. Vorliegend werden bevorzugt Wassergläser verwendet, deren Modul im Bereich von 1,5 bis 3,3 liegt. In der GB 782 205 A ist ein Alkaliwasserglas beschrieben, das sich auch im Rahmen der vorliegenden Erfindung als Binder eignet und das durch Einleitung von CO₂ ausgehärtet werden kann. Weitere geeignete auf Wasserglas basierende Binder sind z.B. aus der DE 199 25 167 A1 , der DE 10 2007 045 649 A1 oder aus der US 5474606 A bekannt. Aus der DE 10 2007 045 649 A1 sind sogenannte „in-situ Wassergläser bekannt“, die bei der Herstellung eines Binders „in-situ“ aus Kieselsäure und einer wässrigen alkalischen Lösung, beispielsweise 40%iger Natronlauge, hergestellt werden. Auch solche Wassergläser eignen sich hervorragend zur Verwendung im Rahmen der vorliegenden Erfindung. Borate sind Salze oder Ester der Borsäuren. Auch Borsäure selbst kann zu den Boraten gezählt werden, sie wird oft auch als Trihydrogenborat bezeichnet. Die Salze sind dadurch gekennzeichnet, dass sie in ihrem Ionengitter als Anion das Borat-Ion BO₃ ^3– bzw. eine kondensierte Form davon (zum Beispiel B₄O₅(OH)₄ ², Tetraborat) enthalten. Als Phosphate können neben klassischen Phosphaten wie Ammoniumphosphat insbesondere auch Polyphosphate und Hydrogenphosphate wie Natriumhydrogenphosphat eingesetzt werden. Bei Polyphosphaten handelt es sich bekanntlich um Kondensationsprodukte von Salzen der ortho-Phosphorsäure (H₃PO₄) mit der allgemeinen Summenformel M_n+2P_nO_3n+1 und der Struktur M-O-[P(OM)(O)-O]_n-M, wobei M ein einwertiges Metall ist. Zu den Polyphosphaten werden sehr häufig auch die kurzkettigen (also eigentlich Oligo-)Phosphate gezählt. Zyklische Polymere werden als Metaphosphate bezeichnet. Zum Einsatz im Rahmen der vorliegenden Erfindung geeignete Binder auf Basis von Polyphosphat und/oder Borat sind beispielsweise in der WO 92/06808 A1 beschrieben. Weitere geeignete phosphatbasierte Binder sind aus der DE 103 59 547 B3 oder aus der DE 195 25 307 A1 oder aus der US 5711792 A bekannt. In einigen besonders bevorzugten Ausführungsformen umfasst der erfindungsgemäß verwendete Binder als Phosphat Natrium-Hexametaphosphat ((NaPO₃)₆).
• 3b Einen wasserlöslichen organischen Binder: Hierzu zählen insbesondere Binder auf Basis von wasserlöslichen Polymeren, beispielsweise auf Basis von Polyvinylalkohol (PVA). Bei Polyvinylalkohol handelt es sich bekanntlich um einen thermoplastischen Kunststoff, der meistens durch Verseifung von Polyvinylacetat hergestellt wird. Der Kunststoff wird meist in Form einer wässrigen Lösung verarbeitet. Sein Schmelzpunkt liegt abhängig vom Hydrolyse- und Polymerisationsgrad in der Regel im Bereich von 200 °C bis 228 °C.

The water-soluble binder is preferably one of the following binders or a combination of at least two of the following binders:

• 3a A Water-Soluble Inorganic Binder: These include, most preferably, water glass based binders, magnesium sulfate based binders, or phosphate and / or borate based binders. Water glasses are both solidified from a melt, glassy, water-soluble alkali metal silicates, especially sodium, potassium, and lithium silicates, as well as their aqueous solutions. Sodium water glasses are particularly suitable for use in the context of the present invention. It is also possible to use a mixture of two or more different water glasses. A characteristic feature of water glasses is their modulus, which is understood to mean the molar ratio SiO ₂ : M ₂ O in the water glass, where M is preferably selected from Li ⁺ , K ⁺ or Na ⁺ . In the present case water glasses are preferably used whose modulus is in the range of 1.5 to 3.3. In the GB 782 205 A is described an alkali water glass, which is also suitable in the context of the present invention as a binder and can be cured by the introduction of CO ₂ . Other suitable water-based binders are for example from DE 199 25 167 A1 , of the DE 10 2007 045 649 A1 or from the US 5474606 A known. From the DE 10 2007 045 649 A1 are known as "in-situ water glasses", which are produced in the production of a binder "in situ" from silica and an aqueous alkaline solution, for example 40% sodium hydroxide solution. Such water glasses are also outstandingly suitable for use in the context of the present invention. Borates are salts or esters of boric acids. Boric acid itself can be counted among the borates, it is often referred to as trihydrogen borate. The salts are characterized in that they contain in their ion lattice as anion the borate ion BO ₃ ^3- or a condensed form thereof (for example B ₄ O ₅ (OH) ₄ ² , tetraborate). As phosphates in addition to classical phosphates such as ammonium phosphate in particular also polyphosphates and hydrogen phosphates such as sodium hydrogen phosphate can be used. Polyphosphates are, as is known, condensation products of salts of ortho-phosphoric acid (H ₃ PO ₄ ) with the general empirical formula M _{n + 2} P _n O _{3n + 1} and the structure MO- [P (OM) (O) -O] _n -M, where M is a monovalent metal. Very often the short-chain (ie actually oligo-) phosphates are also counted among the polyphosphates. Cyclic polymers are referred to as metaphosphates. For use in the context of the present invention suitable binders based on polyphosphate and / or borate are, for example in the WO 92/06808 A1 described. Further suitable phosphate-based binders are from the DE 103 59 547 B3 or from the DE 195 25 307 A1 or from the US 5711792 A known. In some particularly preferred embodiments, the binder used according to the invention comprises sodium hexametaphosphate ((NaPO ₃ ) ₆ ) as the phosphate.
• 3b A water-soluble organic binder: These include in particular binders based on water-soluble polymers, for example based on polyvinyl alcohol (PVA). Polyvinyl alcohol is known to be a thermoplastic material, which is usually produced by saponification of polyvinyl acetate. The plastic is usually processed in the form of an aqueous solution. Its melting point is usually in the range of 200 ° C to 228 ° C, depending on the degree of hydrolysis and polymerization.

• 4a Um einen auf Wasserglas basierenden Binder mit einem Anteil an einem synthetischen oder natürlichen Siliziumdioxid: Derartige Binder sind beispielsweise aus der EP 1 802 409 B1 und aus der DE 10 2007 045 659 A1 bekannt.
• 4b Sofern als Binder ein Polyphosphat zum Einsatz kommt, so handelt es sich hierbei bevorzugt um ein Polyphosphat mit der allgemeinen Summenformel M_n+2P_nO_3n+1 und der Struktur M-O-[P(OM)(O)-O]_n-M (M = einwertiges Metall), insbesondere um Natrium-Hexametaphosphat ((NaPO₃)₆).
• 4c Sofern als Binder ein Borat zum Einsatz kommt, so handelt es sich dabei bevorzugt um ein Polyborat der allgemeinen Formel M_n-2B_nO_2n-1 oder um ein Metaborat der allgemeinen Formel (BO₂)_n ^n–.
• 4d Magnesiumsulfat.

Most preferably, the water-soluble binder is one of the following binders or a combination of the following binders:

• 4a To a water glass-based binder with a proportion of a synthetic or natural silica: Such binders are for example from EP 1 802 409 B1 and from the DE 10 2007 045 659 A1 known.
• 4b If the binder used is a polyphosphate, this is preferably a polyphosphate having the general empirical formula M _{n + 2} P _n O _{3n + 1} and the structure MO- [P (OM) (O) -O] _n -M (M = monovalent metal), in particular sodium hexametaphosphate ((NaPO ₃ ) ₆ ).
• 4c If a borate is used as the binder, it is preferably a polyborate of the general formula M _n-2 B _n O _2n-1 or a metaborate of the general formula (BO ₂ ) _n ^n- .
• 4d magnesium sulfate.

Mixtures of magnesium sulfate and phosphate and / or borate are particularly preferred.

It is particularly preferred that the binders based on polyphosphate and / or borate as well as magnesium sulfate-based binders are combined with pore-filling materials which are anhydrous, in particular also have no water of crystallization. For example, the anhydrous salts described below or mixtures of two or more water-soluble salts are well suited.

• 5a Ein wasserunlösliches natürliches oder synthetisches Wachs, Fett oder Öl, beispielsweise ein Paraffin oder ein Fettsäureester, insbesondere mit einem Schmelzpunkt im Bereich von 20 °C bis 200 °C, besonders bevorzugt mit einem Schmelzpunkt im Bereich von 30 °C bis 100 °C.
• 5b ein wasserlösliches, schmelzbares Polymer, beispielsweise Polyethylenglykol oder niedermolekulares Polypropylenglycol, insbesondere mit einem Schmelzpunkt im Bereich von 20 °C bis 70 °C.
• 5c ein wasserunlösliches, schmelzbares Polymer, beispielsweise ein niedrigschmelzendes thermoplastisches Polyamid oder ein Ethylen-Vinylacetat-Copolymer, insbesondere mit einem Schmelzpunkt im Bereich von 50 °C bis 150 °C, besonders bevorzugt mit einem Schmelzpunkt im Bereich von 50 °C bis 100 °C.
• 5d Ein niedrigschmelzendes Metall oder eine niedrigschmelzende Legierung, wie man es oder sie auch zur Fertigung von Kernen für das Schmelzkern-Spritzgießen verwendet, beispielsweise Bismut oder eine Bismutlegierung, insbesondere mit einem Schmelzpunkt im Bereich von 50 °C bis 150 °C, besonders bevorzugt mit einem Schmelzpunkt im Bereich von 50 °C bis 100 °C.
• 5e Ein wasserlösliches Salz oder eine Mischung aus zwei oder mehr wasserlöslichen Salzen, insbesondere eine geschmolzene Mischung (Schmelze) aus den zwei oder mehr wasserlöslichen Salzen. Es gibt niedrigschmelzende Salze sowie eutektische Gemische solcher Salze, die sich im Rahmen der vorliegenden Erfindung als Porenfüllmaterial einsetzen lassen. Geeignet sind insbesondere Salzmischungen aus Salzen, welche sich aus Kationen der Alkali- und Erdalkalimetalle sowie aus Anionen der Typen Chlorid, Nitrit, Nitrat, Carbonat, Hydroxid, Fluorid, Cyanat und Sulfat zusammensetzen. Besonders geeignet sind beispielsweise Nitrate wie Lithium-, Kalium- oder Natriumnitrat oder Nitrite wie Lithium-, Kalium- oder Natriumnitrit oder Mischungen enthaltend ein Nitrat oder Nitrit oder bevorzugt zwei oder mehr Nitrate und/oder Nitrite. Es lässt sich beispielsweise aus 40 Gew.-% NaNO₂, 7 Gew.-% NaNO₃ und 53 Gew.-% KNO₃ ein ternäres Gemisch mit einer Schmelztemperatur von 142 °C bilden. Ein geeignetes binäres Gemisch aus 45 Gew.-% NaNO₂ und 55 Gew.-% KNO₃ weist eine Schmelztemperatur von 141 °C auf. Die Salzmischungen können auch Chloride enthalten, beispielsweise Magnesiumchlorid, Kaliumchlorid und/oder Natriumchlorid. Aus Natriumnitrat und Natriumchlorid lässt sich beispielsweise ein binäres Gemisch mit einem Schmelzpunkt von 282 °C bilden. Bevorzugt werden im Rahmen der vorliegenden Erfindung als Porenfüllmaterial ausschließlich Salze und Salzmischungen eingesetzt, die frei von Wasser, insbesondere auch frei von Kristallwasser, sind. Besonders bevorzugt werden Salze und Salzmischungen mit einer dynamischen Viskosität von weniger als 4 mPas (bei 300 °C), bevorzugt von weniger als 3 mPas (bei 300 °C), besonders bevorzugt von weniger als 2,5 mPas (bei 300 °C), eingesetzt. Weiterhin ist es bevorzugt, dass die Salze und Salzmischungen einen Schmelzpunkt im Bereich von 20 °C bis 500 °C, bevorzugt von 30 °C bis 380 °C, aufweisen. In einigen bevorzugten Ausführungsformen können die Salze und Salzmischungen einen Schmelzpunkt im Bereich von 30 °C bis 300 °C, bevorzugt von 30 °C bis 150 °C, aufweisen.

The pore filling material is preferably one of the following substances or a combination of at least two of the following substances:

• 5a A water-insoluble natural or synthetic wax, fat or oil, for example a paraffin or a fatty acid ester, in particular having a melting point in the range from 20 ° C to 200 ° C, particularly preferably having a melting point in the range from 30 ° C to 100 ° C.
• 5b, a water-soluble, meltable polymer, for example polyethylene glycol or low molecular weight polypropylene glycol, in particular having a melting point in the range of 20 ° C to 70 ° C.
• 5c is a water-insoluble, meltable polymer, for example a low-melting thermoplastic polyamide or an ethylene-vinyl acetate copolymer, in particular having a melting point in the range from 50 ° C. to 150 ° C., particularly preferably having a melting point in the range from 50 ° C. to 100 ° C. ,
• 5d A low melting point metal or alloy, such as is used to make cores for melt core injection molding, such as bismuth or a bismuth alloy, especially having a melting point in the range of 50 ° C to 150 ° C, more preferably with a melting point in the range of 50 ° C to 100 ° C.
• 5e A water-soluble salt or a mixture of two or more water-soluble salts, in particular a molten mixture (melt) of the two or more water-soluble salts. There are low-melting salts and eutectic mixtures of such salts, which can be used in the context of the present invention as a pore filling material. Salt mixtures of salts which are composed of cations of the alkali metals and alkaline earth metals and of anions of the types chloride, nitrite, nitrate, carbonate, hydroxide, fluoride, cyanate and sulfate are particularly suitable. Particularly suitable are, for example, nitrates such as lithium, potassium or sodium nitrate or nitrites such as lithium, potassium or sodium nitrite or mixtures containing a nitrate or nitrite or preferably two or more nitrates and / or nitrites. For example, from 40% by weight of NaNO ₂ , 7% by weight of NaNO ₃ and 53% by weight of KNO _{3, it is possible to form} a ternary mixture having a melting temperature of 142 ° C. A suitable binary mixture of 45 wt .-% NaNO ₂ and 55 wt .-% KNO ₃ has a melting temperature of 141 ° C. The salt mixtures may also contain chlorides, for example magnesium chloride, potassium chloride and / or sodium chloride. For example, a binary mixture having a melting point of 282.degree. C. can be formed from sodium nitrate and sodium chloride. In the context of the present invention, pore-filling material used is preferably exclusively salts and salt mixtures which are free from Water, especially free of water of crystallization, are. Particular preference is given to salts and salt mixtures having a dynamic viscosity of less than 4 mPas (at 300 ° C.), preferably less than 3 mPas (at 300 ° C.), more preferably less than 2.5 mPas (at 300 ° C.). used. Furthermore, it is preferred that the salts and salt mixtures have a melting point in the range of 20 ° C to 500 ° C, preferably from 30 ° C to 380 ° C. In some preferred embodiments, the salts and salt mixtures may have a melting point in the range of from 30 ° C to 300 ° C, preferably from 30 ° C to 150 ° C.

In many embodiments, it is quite generally preferred that the pore filling material is a material that is not water-soluble and has a melting point below the melting point of the particular particulate molding material used, preferably at least 20 ° C below the melting point, especially at least 50 ° C. This temperature difference is particularly relevant if particles of organic materials are used as the particulate molding material.

In cases where it is preferred that the pore-filling material be water-soluble, the melting point of the pore-filling material plays a comparatively minor role.

• 7a Als partikulärer Formgrundstoff wird ein organisches und/oder ein anorganisches wasserunlösliches Material verwendet. Als Binder wird ein wasserlöslicher anorganischer Binder verwendet. Als Porenfüllmaterial wird ein wasserlösliches Polymer verwendet. Ein Kern, der aus dieser Kombination aus Formgrundstoff, Binder und Porenfüllmaterial hergestellt wurde, lässt sich nach einem Gussvorgang aus einem Gussteil in der Regel leicht mittels Wasser herauslösen. Da sowohl das Porenfüllmaterial als auch der Binder wasserlöslich sind, verliert der Kern in Kontakt mit Wasser schnell seine strukturelle Integrität und zerfällt.
• 7b Als partikulärer Formgrundstoff wird ein organisches und/oder ein anorganisches wasserunlösliches Material verwendet. Als Binder wird ein wasserlöslicher, anorganischer Binder verwendet. Als Porenfüllmaterial wird ein wasserunlösliches natürliches oder synthetisches Wachs, Fett oder Öl oder ein wasserunlösliches, schmelzbares Polymer oder ein Metall oder eine Metalllegierung (beide niedrigschmelzend) verwendet. Ein Kern, der aus dieser Kombination aus Formgrundstoff, Binder und Porenfüllmaterial hergestellt wurde, zeichnet sich dadurch aus, dass er aufgrund des hydrophoben Porenfüllmaterials wasserabweisend ist. Er ist von sich aus also nicht wasserlöslich. Erwärmt man allerdings den Kern, so schmilzt das Porenfüllmaterial und der wasserlösliche Binder kann mit Wasser, beispielsweise dem Wasser eines Wasserbads, unmittelbar in Kontakt treten. Der dann einsetzende Lösungsvorgang resultiert in einer Zersetzung des Kerns.
• 7c Als partikulärer Formgrundstoff wird ein organisches und/oder ein anorganisches wasserunlösliches Material verwendet. Als Binder wird ein wasserlöslicher organischer Binder verwendet. Als Porenfüllmaterial wird ein wasserlösliches Polymer verwendet. Ein Kern, der aus dieser Kombination aus Formgrundstoff, Binder und Porenfüllmaterial hergestellt wurde, verhält sich in Kontakt mit Wasser ähnlich wie ein Kern gemäß 7a.
• 7d Als partikulärer Formgrundstoff wird ein organisches und/oder ein anorganisches wasserunlösliches Material verwendet. Als Binder wird ein wasserlöslicher, organischer Binder verwendet. Als Porenfüllmaterial wird ein wasserunlösliches natürliches oder synthetisches Wachs, Fett oder Öl oder ein wasserunlösliches, schmelzbares Polymer oder ein Metall oder eine Metalllegierung verwendet. Ein Kern, der aus dieser Kombination aus Formgrundstoff, Binder und Porenfüllmaterial hergestellt wurde, verhält sich ähnlich wie ein Kern gemäß 7b.
• 7e Als partikulärer Formgrundstoff wird ein organisches und/oder ein anorganisches wasserlösliches Material verwendet. Als Binder wird ein wasserlöslicher anorganischer oder organischer Binder verwendet. Als Porenfüllmaterial wird ein wasserunlösliches natürliches oder synthetisches Wachs, Fett oder Öl oder ein wasserunlösliches, schmelzbares Polymer oder ein Metall oder eine Metalllegierung (beide niedrigschmelzend) verwendet. Ein Kern, der aus dieser Kombination aus Formgrundstoff, Binder und Porenfüllmaterial hergestellt wurde, verhält sich ähnlich wie ein Kern gemäß 7b.

Within the scope of the present invention, molds having the following combinations of mold base, binder and pore filler are particularly preferred:

• 7a An organic and / or an inorganic water-insoluble material is used as the particulate molding material. As the binder, a water-soluble inorganic binder is used. As the pore filling material, a water-soluble polymer is used. A core made from this combination of mold base, binder and pore filler material is usually easy to dissolve with water after casting from a casting. Because both the pore filler and the binder are water soluble, the core quickly loses its structural integrity upon contact with water and disintegrates.
• 7b An organic and / or an inorganic water-insoluble material is used as the particulate molding material. The binder used is a water-soluble inorganic binder. As the pore-filling material, a water-insoluble natural or synthetic wax, fat or oil or a water-insoluble fusible polymer or a metal or a metal alloy (both low-melting) is used. A core made from this combination of mold base, binder and pore filler is characterized by being hydrophobic due to the hydrophobic pore-filling material. He is therefore not water-soluble on his own. However, when heating the core, the pore-filling material melts and the water-soluble binder can come into direct contact with water, for example the water of a water bath. The then beginning solution process results in a decomposition of the core.
• 7c An organic and / or an inorganic water-insoluble material is used as the particulate molding material. The binder used is a water-soluble organic binder. As the pore filling material, a water-soluble polymer is used. A core made from this combination of mold base, binder and pore filler behaves in contact with water similar to a core according to Fig. 7a.
• 7d An organic and / or an inorganic water-insoluble material is used as the particulate molding material. The binder used is a water-soluble organic binder. As the pore filling material, a water-insoluble natural or synthetic wax, fat or oil or a water-insoluble fusible polymer or a metal or a metal alloy is used. A core made from this combination of mold base, binder and pore filler behaves similar to a core according to Fig. 7b.
• 7e An organic and / or an inorganic water-soluble material is used as the particulate molding material. The binder used is a water-soluble inorganic or organic binder. As the pore-filling material, a water-insoluble natural or synthetic wax, fat or oil or a water-insoluble fusible polymer or a metal or a metal alloy (both low-melting) is used. A core made from this combination of mold base, binder and pore filler behaves similar to a core according to Fig. 7b.

It is particularly preferred that the pore filling material in the form - based on its total volume - in a proportion of 1 to 80 vol .-%, preferably from 1 to 50 vol .-%, particularly preferably from 10 to 50 vol .-%, is included. It fills the pores of the mold preferably more than 25%, in particular more than 50%, particularly preferably more than 75%, from. In some embodiments, all pores of the mold are filled with the pore filling material. In some other embodiments, the pores lying at and below the surface of the mold are filled with the pore filling material, while in the interior of the mold pores filled with pore filling material do not exist.

The present invention further relates to a method for producing a mold used for producing composite fiber bodies or castings, in particular for producing a core serving for producing voids in fiber composite bodies or castings made of plastic, particularly preferably a mold or a core, as described above were.

In the method, a mold having pores is first produced from one of the described particulate mold raw materials and one of the described water-soluble binders. In preferred embodiments, the pores are then filled with one of the described liquid pore filling materials. However, it is also possible that the pore filling material is processed in the same step with the molding material and / or with the binder.

In preferred embodiments, an organofunctional siloxane, in particular sodium (3- (trihydroxysilyl) propyl) methyl phosphonate, may be added to the molding material mixture of the molding base material and the binder and optionally the pore filling material. This is particularly preferred when using one of the water glass based binders.

As an alternative to the organofunctional silane, molding mixtures with water glass-based binders may also be added to sodium nitrate and / or sodium nitrite.

The porosity of the mold produced in the first step can be adjusted, for example, via the particle size distribution of the particulate molding base used. For example, large particles with a largely uniform size lead to higher porosities than mixtures of large and small particles.

Particularly preferably, the mold has an open-pored structure.

For the preparation of the mold from the particulate mold base and the water-soluble binder, one can resort to conventional methods such as the production in a molding box. But it is also possible, in most cases even preferred, to produce the mold by means of 3D printing.

In many cases it is advantageous to subject the mold made of the particulate molding material and the water-soluble binder to a hardening step before further treatment, for example by heating or treatment with microwave radiation.

Furthermore, in many cases it is preferred to dry the mold prior to its further processing, in particular to remove all unbound water.

For filling the pores, the pore filling material is preferably provided in liquid form and pressed or sucked into the pores of the mold by means of pressure or underpressure. For example, for this purpose, a mold with an open-pored structure can be inserted into a vacuum chamber, which is subsequently evacuated. After adjusting the desired negative pressure, the liquid pore filling material is then injected into the vacuum chamber and drawn into the pores of the mold. As a rule, the pore filling material is then allowed to cool until it solidifies. Thereafter, the finished shape of the vacuum chamber can be removed.

The pore filling material can also be introduced without pressure into the pores of the mold, in particular if it has a low viscosity. For example, the pore filling material may be provided in liquid form and the mold immersed in the liquid pore filling material, especially until it is completely covered by the pore filling material.

Such a treated form usually has an extremely high storage stability, since it, even if it was made using a strong hygroscopic binder, a high resistance to moisture, especially humidity, and thus also has a long shelf life. In addition, the treatment with the pore filling material increases the strength of the mold partly significant.

The molds and cores according to the invention or the molds and cores produced by the process described are preferably used for the production of fiber composite bodies or of molded plastic parts. However, the shapes and cores are also very well suited for the processing of concrete and ceramic materials, especially as forms and shells for concrete and ceramic processing.

Some embodiments of the molds and cores, in particular those with an inorganic, water-insoluble molding material and a binder based on polyphosphate and / or borate and the water-soluble salt or the mixture of two or more water-soluble salts as pore filling material are also suitable for processing liquid aluminum, especially for die-cast aluminum.

• – der Kern in einer Gießform angeordnet und
• – in die Gießform wird ein flüssiges Polymermaterial oder ein flüssiger Polymervorläufer eingebracht.

For the production of fiber composite bodies or molded parts made of plastic with a cavity is preferred

• - The core is arranged in a mold and
• - In the mold, a liquid polymer material or a liquid polymer precursor is introduced.

After solidification and / or curing of the polymer material or the polymer precursor, the core can be removed. However, this is not mandatory.

Upon solidification and / or curing, the polymeric material or polymer precursor transforms to the plastic. It is of particular advantage in this case that penetration of the polymer material or of the polymer precursor into the pores of the mold is prevented or at least counteracted, since they are indeed filled with the pore filling material.

The liquid polymer material may in principle be any polymer material which can be converted into a liquid state by melting, for example a polyamide. The polymer precursor can be, for example, a reactive mixture of a binder and a hardener adapted to the binder, for example a hydroxy-functional binder and an isocyanate-functional hardener (for producing a polyurethane). Excellent epoxy resins and hardeners can be used as reactive mixtures.

In particularly preferred embodiments, the core may be particularly cooled to a temperature in the range of -20 ° C to 20 ° C prior to being contacted with the polymeric material or polymer precursor or in the cladding with the fiber material described below preferably to a temperature in the range of -20 ° C to 15 ° C, in particular to a temperature in the range of -20 ° C to 10 ° C. By cooling, if necessary, a significant increase in the hardness of the pore filling material and thus the strength of the core as a whole is brought about. Thus, in principle, pore filling materials can also be used which, at temperatures above 20 ° C., make an insufficient contribution to the strength of the core.

To produce fiber composite bodies, the core is preferably sheathed with a fiber material before it is placed in the casting mold. The fibers may be, for example, glass fibers, carbon fibers, ceramic fibers, aramid fibers, boron fibers, steel fibers, natural fibers and nylon fibers. The fibers can be wrapped or braided around the core. However, it is also possible, e.g. To arrange nets, mats or fleeces from the fibers on the surface of the core.

In preferred embodiments of the inventive method, a pore filling material is used which has a melting and / or boiling point which is above the processing temperature of the polymer material or the polymer precursor used, preferably at least 5 ° C, more preferably at least 20 ° C, in particular at least 50 ° C. , Conversely, it is preferred that the polymer material or polymer precursor used during processing does not reach temperatures exceeding said temperature difference values. The pore filling material and the polymer material or the polymer precursor are therefore preferably matched to one another. For example, the processing temperature of some epoxy resins is in the range of 150 ° C to 180 ° C. The pore filling material used should then ideally have a melting point of at least 190 ° C, preferably of at least 200 ° C, in particular of at least 230 ° C.

As already mentioned above, the core is removed after solidification and / or curing of the polymer material or the polymer precursor by means of water and / or heating. If the pore filling material is water-soluble, the core can be removed exclusively by means of water. However, if the pore-filling material is water-repellent, the core must be converted to a water-soluble state. This is done, as already stated above, by melting the pore filling material.

In principle, however, it is also possible to remove the core by mechanical methods such as shaking, by ultrasound or by means of a high-pressure water jet.

When using water-repellent pore-filling materials, the pore-filling material and the polymeric material or polymer precursor are preferably matched to one another such that the pore-filling material has a melting temperature which is below the melting or decomposition temperature of the plastic formed from the polymeric material or polymer precursor, preferably at least 5 ° C preferably at least 20 ° C, especially at least 50 ° C.

Further features of the invention and advantages resulting from the invention will become apparent from the following description of some preferred embodiments. These are merely illustrative and for a better understanding of the invention and are in no way limiting.

I. Providing a voided core of a particulate molding base and a water-soluble binder

A With molding compounds with a binder based on water glass

• • 1,80 Gewichtsteile Alkaliwasserglas mit einem Modul SiO₂:Na₂O von ca. 2,4
• • 0,90 Gewichtsteile einer 50 %igen Lösung von Natrium-(3-(trihydroxysilyl)propyl)methylphosphonat (DOW CORNING Q1-6083 Antifreeze Additive)
• • 1,00 Gewichtsteile amorphes, pyrogenes Siliziumdioxid
• • 96,3 Gewichtsteile Quarzsand H32

The following components were processed into a molding material mixture:

• • 1.80 parts by weight of alkali water glass with a modulus SiO ₂ : Na ₂ O of approx. 2.4
• 0.90 parts by weight of a 50% solution of sodium (3- (trihydroxysilyl) propyl) methyl phosphonate (DOW CORNING Q1-6083 Antifreeze Additive)
• • 1.00 parts by weight of amorphous fumed silica
• • 96.3 parts by weight of quartz sand H32

For the preparation of the molding material mixture, the quartz sand were placed in a laboratory paddle mixer and added with stirring the water glass and methylphosphonate. After the mixture was stirred for one minute, the amorphous silica was added with further stirring.

The molding material mixture was introduced by means of compressed air into a mold. To accelerate the curing of the mixture, hot air was passed through the mold. The mold was opened and the core was removed. Immediately thereafter, the core was dried.

B With molding compounds with a binder based on "in situ" waterglass

• • 1,00 Gewichtsteile kolloidales Kieselsol (Ludox HS 40, Grace Chemicals, Columbia, MD, USA)
• • 0,40 Gewichtsteile NaOH (40 %ig)
• • 0,60 Gewichtsteile amorphes Siliziumdioxid (Flugasche Pozzolan aus Montserrat)
• • 98,0 Gewichtsteile Quarzsand H32

The following components were processed into a molding material mixture:

• 1.00 parts by weight colloidal silica sol (Ludox HS 40, Grace Chemicals, Columbia, MD, USA)
• 0.40 parts by weight NaOH (40%)
• 0.60 parts by weight of amorphous silica (fly ash pozzolan from Montserrat)
• • 98.0 parts by weight of quartz sand H32

To prepare the molding material mixture, the quartz sand was placed in a laboratory mixer and added with stirring, the colloidal silica sol and the sodium hydroxide solution and the amorphous silica.

The molding material mixture was introduced by means of compressed air into a mold. To accelerate the curing of the mixture, hot air was passed through the mold. The mold was opened and the core was removed. Immediately thereafter, the core was dried.

C With molding compounds with a binder based on borate / phosphate

• • 2,50 Gewichtsteile Di-Natriumoctaborat-Tetrahydrat (TIM-Borat der Firma Inkabor, P.I. Río Seco Arequipa – Perú)
• • 2,50 Gewichtsteile Natriumhydrogenphosphat
• • 5,00 Wasser
• • 90,0 Gewichtsteile Quarzsand H32

The following components were processed into a molding material mixture:

• 2.50 parts by weight of di-sodium octaborate tetrahydrate (TIM borate from Inkabor, PI Río Seco Arequipa - Perú)
• • 2.50 parts by weight of sodium hydrogen phosphate
• • 5.00 water
• • 90.0 parts by weight of quartz sand H32

To prepare the molding material mixture, the glass beads were placed in a laboratory paddle mixer and added with stirring, the di-sodium octaborate tetrahydrate and the sodium hydrogen phosphate and the water and the sodium hydroxide solution.

The molding material mixture was introduced by means of compressed air into a mold. To accelerate the curing of the mixture, hot air was passed through the mold. The mold was opened and the core was removed. Immediately thereafter, the core was dried.

D With molding compounds with a binder based on borate / phosphate

• • 2,50 Gewichtsteile Di-Natriumtetraborat-Decahydrat
• • 2,50 Gewichtsteile Natriumhydrogenphosphat
• • 5,00 Gewichtsteile Wasser
• • 90,0 Gewichtsteile Glaskugeln Quarzsand H32

The following components were processed into a molding material mixture:

• • 2.50 parts by weight of di-sodium tetraborate decahydrate
• • 2.50 parts by weight of sodium hydrogen phosphate
• • 5.00 parts by weight of water
• • 90.0 parts by weight of glass beads quartz sand H32

For the preparation of the molding material mixture, the glass beads were placed in a laboratory paddle mixer and added with stirring, the borax and the sodium hydrogen phosphate and the water and the sodium hydroxide solution.

The molding material mixture was introduced by means of compressed air into a mold. To accelerate the curing of the mixture, hot air was passed through the mold. The mold was opened and the core was removed. Immediately thereafter, the core was dried.

E With molding compounds with a binder based on borate / phosphate

• • 1,25 Gewichtsteile Di-Natriumoctaborat-Tetrahydrat
• • 1,25 Gewichtsteile Natriumhydrogenphosphat
• • 2,50 Gewichtsteile Wasser
• • 95,0 Gewichtsteile Glaskugeln (Silibeads der Firma Sigmund Lindner GmbH, 95485 Warmensteinach, Deutschland)

The following components were processed into a molding material mixture:

• 1.25 parts by weight of di-sodium octaborate tetrahydrate
• • 1.25 parts by weight of sodium hydrogen phosphate
• • 2.50 parts by weight of water
• 95.0 parts by weight of glass beads (Silibeads from Sigmund Lindner GmbH, 95485 Warmensteinach, Germany)

To prepare the molding material mixture, the glass beads were placed in a laboratory paddle mixer and added with stirring, the di-sodium octaborate tetrahydrate and the sodium hydrogen phosphate and the water and the sodium hydroxide solution.

The molding material mixture was introduced by means of compressed air into a mold. To accelerate the curing of the mixture, hot air was passed through the mold. The mold was opened and the core was removed. Immediately thereafter, the core was dried.

II. Filling the pores of the cores produced according to I with a pore filling material

F With a melt of two or more water-soluble salts as pore filling material

A mixture of 40% by weight NaNO ₂ , 7% by weight NaNO ₃ and 53% by weight KNO ₃ was converted by heating into a homogeneous, low-viscosity melt. In this melt, the cores A-E prepared according to I were immersed, after they were heated in an oven to a temperature of 140 ° C. The melt penetrated the pores of the cores and closed them. After cooling, the cores thus treated had a substantially nonporous surface.

G With a synthetic wax

A synthetic paraffin wax with a melting point of 90 ° C was converted by heating in a liquid, low viscosity state. The cores A-E prepared according to I. were exposed to a vacuum in a vacuum chamber. In this chamber, the liquid paraffin was injected. The paraffin penetrated the pores of the nuclei and closed them. After cooling to room temperature and subsequent removal of the cores from the vacuum chamber, the treated cores had a substantially nonporous surface.

III. Producing a plastic molding with an internal cavity

The cores treated according to F and G were placed in a mold into which after closing the mold, a polyamide having a processing temperature of 85 ° C was injected.

After curing and cooling of the polyamide, the plastic molding was removed from the mold.

IV. Producing a fiber composite body with an internal cavity

The cores treated according to F and G were wrapped with carbon fibers and placed in a mold into which after closing the mold a polyamide having a processing temperature of 85 ° C was injected.

After curing and cooling of the polyamide, the fiber composite body was removed from the mold.

V. Removal of the cores from the III. and IV. manufactured plastic moldings and fiber composite bodies

To remove the cores, the produced plastic moldings and fiber composite bodies were treated with heated to 95 ° C water. Both cores treated according to F and G were easily removed.

In the cores treated according to G, the paraffin wax used melted as a result of contact with the water. The melted paraffin wax was then easily separated and recycled.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• GB 782205 A [0022]
• DE 19925167 A1 [0022]
• DE 102007045649 A1 [0022, 0022]
• US 5474606 A [0022]
• WO 92/06808 A1 [0022]
• DE 10359547 B3 [0022]
• DE 19525307 A1 [0022]
• US 5711792 A [0022]
• EP 1802409 B1 [0023]
• DE 102007045659 A1 [0023]

Claims (15)

For the production of fiber composite bodies or castings made of plastic serving form of a particulate mold base material and a binder, wherein The form has pores, The pores are filled with a pore filling material, • the binder is water-soluble and • The pore filling material is liquefiable by increasing the temperature and is chemically inert to the binder and / or the particulate molding material. Mold according to Claim 1, characterized in that the particulate molding base material consists of one of the following components or contains at least one of the following components: particles of inorganic, water-insoluble materials, for example sand particles, glass particles, particles of a ceramic or of a glass ceramic, particles of one Glass frit, silicate particles such as particles of aluminum silicate, particles of a metal oxide such as aluminum oxide, particles of a metal nitride, particles of a titanate, particles of a zirconate, particles of an aluminate, particles of a carbide, for example silicon carbide, particles of a metal or a Metal alloy, graphite particles, particles of water-insoluble salts, particles of inorganic, water-soluble materials, for example salts of the group with sodium chloride (NaCl), sodium nitrate (NaNO ₃ ), potassium chloride (KCl), potassium nitrate (KNO ₃ ) and sodium carbonate (Na ₂ CO ₃ ) or M isocyanates of these salts, particles of organic, water-insoluble materials, for example of a water-insoluble polymer such as polystyrene, polyethylene, polypropylene, polyurethane or polycarbonate, particles of organic, water-soluble materials, for example of a water-soluble polymer such as polyvinyl alcohol (PVA) or a salt an organic acid such as sodium acetate, particles of an inorganic-organic composite material, for example a plastic, in which inorganic particles are embedded. Mold according to Claim 1 or Claim 2, characterized in that the water-soluble binder is a water-soluble inorganic binder, for example a binder based on water glass or on magnesium sulfate or on phosphate and / or borate and / or a water-soluble organic compound Binder, for example based on a water-soluble polymer such as polyvinyl alcohol (PVA) is. Mold according to one of the preceding claims, characterized in that the water-soluble binder • a water-based glass binder having a proportion of a synthetic or natural silica and / or • a phosphate, particularly a polyphosphate having the general empirical formula M _{n + 2} P _n O _{3n + 1} and the structure MO- [P (OM) (O) -O] _n -M (M = monovalent metal), in particular sodium hexametaphosphate ((NaPO ₃ ) ₆ ) and / or • a borate, in particular polyborate of the general formula M _n-2 B _n O _2n-1 or a metaborate of the general formula (BO ₂ ) _n ^n- and / or • magnesium sulfate. Mold according to one of the preceding claims, characterized in that the pore filling material is particularly preferably a natural or synthetic wax, fat or oil, for example paraffin or fatty acid esters, in particular having a melting point in the range from 20 ° C to 200 ° C having a melting point in the range from 30 ° C to 200 ° C, in particular from 30 ° C to 100 ° C, or • a water-soluble, meltable polymer, for example polyethylene glycol, in particular having a melting point in the range from 30 ° C to 70 ° C, or • a water-insoluble, meltable polymer, for example a low-melting thermoplastic polyamide or an ethylene-vinyl acetate copolymer, in particular having a melting point in the range from 50 ° C to 150 ° C, particularly preferably having a melting point in the range from 50 ° C to 100 ° C, or • a metal or a metal alloy, for example bismuth or a bismuth alloy, in particular with a melt zpunkt in the range of 50 ° C to 150 ° C, particularly preferably with a melting point in the range of 50 ° C to 100 ° C or • a water-soluble salt or a mixture of two or more water-soluble salts, in particular with a melting point in the range of 20 ° C to 500 ° C, more preferably having a melting point in the range of 30 ° C to 380 ° C, is. Mold according to one of the preceding claims, characterized in that the pore filling material • is not water-soluble and has a melting point which is below the melting point of the particulate mold base used, preferably at least 20 ° C, in particular at least 50 ° C, or • is water soluble. Mold according to any one of the preceding claims, characterized in that it comprises (a) as the particulate molding material an organic or inorganic, water-insoluble material and as binder a water-soluble inorganic binder and as pore-filling material a water-soluble polymer or (b) as particulate molding material an organic or inorganic, water-insoluble material and as binder a water-soluble inorganic binder and as pore filling material natural or synthetic wax, fat or oil or a water-insoluble, fusible polymer or a metal or a metal alloy or (c) as particulate molding material an organic or inorganic, water-insoluble material and as a binder water-soluble organic binder and as a pore filling material natural or synthetic wax, fat or oil or a water-soluble polymer or a water-insoluble fusible polymer or a metal or a Metalllegierun g or (d) comprises as particulate molding material an organic or inorganic, water-insoluble material and as binder a water-soluble, organic binder and as a pore filling material a natural or synthetic wax, fat or oil or a water-soluble polymer or a water-insoluble fusible polymer. Mold according to one of the preceding claims, characterized in that it contains the filler in a proportion of 1 to 80 vol .-%, preferably between 10 and 50 vol .-%. A process for producing a mold used for producing fiber composite bodies or castings from plastic, in particular according to one of claims 1 to 8, wherein a mold having pores is produced from a particulate mold base material and a water-soluble binder, in particular by 3D printing, and the pores are provided with a liquid pore filling material which behaves chemically inert with respect to the binder and / or the molding material. A method according to claim 9, characterized in that the pore filling material is provided in liquid form and is pressed or sucked without pressure or by means of pressure or negative pressure in the pores of the core. Process for producing fiber composite bodies or molded parts from plastic, wherein a mold according to one of claims 1 to 8 is used. A method according to claim 11, characterized in that a core suitable for producing voids in fiber composite bodies or castings made of plastic is used as the mold and the core is placed in a casting mold, a liquid polymer material or a liquid polymer precursor is introduced into the casting mold, and optionally, after solidification and / or curing of the polymeric material or polymer precursor, the core is removed. A method according to claim 12, characterized in that the core is coated with a fiber material before it is placed in the mold. Method according to one of claims 12 or 13, characterized in that • the pore filling material has a melting and / or boiling point which is above the processing temperature of the polymer material or the polymer precursor used, preferably at least 5 ° C, particularly preferably at least 20 ° C, in particular at least 50 ° C above, and / or that the pore filling material and the polymer material or the polymer precursor are matched to one another such that the pore filling material has a melting temperature which is below the melting or decomposition temperature of the plastic formed from the polymer material or the polymer precursor. Method according to one of claims 12 to 14, characterized in that the core is removed after solidification and / or curing of the polymer material or the polymer precursor by means of water and / or heating.