WO2020049075A1 - Method for producing a metal casting or a cured moulding using an aliphatic binder system - Google Patents

Abstract

A method is described (i) for producing a metal casting and/or (ii) for producing a cured moulding, selected from the group consisting of a casting mould, a core and a feeder, for use when casting metal castings, and also a moulding material mixture for use in this method. Also described is the use of an aliphatic polymer, comprising hydroxy groups and crosslinked by one or more aliphatic polyisocyanates, as a binder of a moulding for use when casting metal castings. Likewise described is a cured moulding for use when casting metal castings, including a moulding with a green bond, and preferably able to be produced by the method according to the invention. Also described is the use of biopolymers from the group of poly-D-glucosamines as a binder or binder component for producing a moulding with a green bond in the foundry industry.

Description

 Process for producing a metallic casting or a hardened molded part using an aliphatic binder system

The present invention relates to a process (i) for producing a metallic casting and / or (ii) for producing a hardened molding, selected from the group consisting of casting mold, core and feeder, for use in casting metallic castings, and a molding material mixture, in particular for use in this process.

Furthermore, the present invention relates to the use of an aliphatic polymer, which is crosslinked by one or more aliphatic polyisocyanates and comprises hydroxyl groups, as a binder of a molded part for use in the casting of metallic castings. The present invention likewise relates to a hardened molded part for use in the casting of metallic castings, including a molded part which is stable on green, and preferably can be produced by the process according to the invention.

The present invention also relates to the use of biopolymers from the group of poly-D-glucosamines as binders or binder components for the production of a green part which is stable in the foundry industry. Foundry molded parts used in metal casting (hereinafter also referred to as "molded parts"), in particular cores, molds and feeders (including feeder caps and coverings or feeder sleeves), consist regularly of a refractory base material which, depending on the application, contains one or more refractory solids , for example quartz sand, and / or one or more particulate light fillers, for example spheres from fly ash, and a suitable binder which the molded part after removal from the mold (such as a molded part box such as a core box or a molded box, see below) gives sufficient mechanical strength. In the uncured state, the mixture of molding raw material and binding agent, which may also contain other additives, is referred to as a “molding material mixture”.

Refractory solids are preferably particulate and in a free-flowing form, so that after incorporation into a molding material mixture they can be filled into a suitable hollow mold (the molding tool, see above) and compressed there. For this purpose, feeders and cores are usually introduced into a mold in core shooters under pressure, i.e. “shot”. Smaller moldings are often also shot, while larger moldings, especially larger molds, are usually molded in a mold box by stamping. In general, all molded parts can also be produced by stamping in appropriate shapes, for example using the hand molding method. In order to obtain shootable or tampable molding material mixtures, their moisture content, and in the case of water-based binders in particular their water content, must be set accordingly so that the molding material mixture has sufficient dimensional stability for the corresponding molding process, or the ratio of the liquid components of the molding material mixture to their solid content Components are set accordingly.

Molded parts such as molds, cores and feeders must meet various typical foundry requirements. The type and extent of the fulfillment of these requirements are essentially determined by the binder used to manufacture them:

After the production of a molded part, ie immediately after the molded part has been removed from the production tool, the molded part should have the highest possible strength. The strengths at this point in time (“initial strength”, also referred to as “green stability”, see also below) are particularly important for the safe handling of cores, molds or feeders when they are removed from the manufacturing tool. A high so-called final strength (i.e. the strength after the molded part has completely hardened) and a high temperature resistance of a molded part during the actual metal casting are important, especially for cores and molds, so that the molded part does not deform under the weight of the cast metal (i.e. a good one Retains its shape during the casting process (also known as “cast resistance”) and the metal casting made with it can be made as far as possible without casting defects. In this context, it is also important that the molded parts used have as clean or smooth a surface as possible without distortions or the like, since otherwise surface defects of the molded parts can be transferred to the surfaces of the metal castings produced with them.

Furthermore, the high resistance of the molded parts to aqueous moisture is a great advantage. In general, such a high level of moisture resistance allows the molded parts to be stored for a longer period of time, even under demanding climatic conditions (warm, humid climate) and ideally over several days or weeks, which makes it easier or even possible to produce molded parts in stock and store them. As a result, the industrial production of metal castings with these molded parts gains considerable flexibility. It has also been shown that with all molded parts used in metal casting, in particular with feeders, water absorption (for example during their storage due to the absorption of moisture from the air) can lead to the corresponding water deposits at the high temperatures of the metal casting Form vapor bubbles, which can lead to the formation of voids in the metal casting, which then makes it unusable. In extreme cases, sudden water vapor formation can even lead to explosions. A high level of moisture resistance of the molded parts is also advantageous, since it allows, for example, their use with different types of size and in particular also with water-based sizes. Finishing agents are release agents on a ceramic basis, which in certain cases are intended to prevent direct contact between molded parts, for example cores, and the molten metal, so that they can better withstand the high thermal loads during metal casting. In view of the high quality of the metal cast, it is also desirable that molded parts remove as little thermal energy from the molten metal as possible, for example through reactions of the binder, such as can occur in known melting reactions of water glass binders. Such a withdrawal of thermal energy can lead to premature solidification of the molten metal and thus to an incomplete casting. This characterization of a binder by its properties of absorbing thermal energy itself, is also referred to as its "deterrent behavior". Particularly in the case of feeders, a particularly good thermal insulation effect is desired or necessary in order to keep the molten metal liquid as long as possible during the casting of the metal and to achieve the lowest possible formation of voids in the metal casting, any void formation occurring as far as possible outside the finished metal casting ( for example only in the feeder).

After the casting process has taken place, a molded part should then decompose as much as possible under the influence of the heat emitted by the casting metal in such a way that it loses its mechanical strength, that is to say the cohesion between individual particles of the base material is lost. In the ideal case, the molded part then disintegrates into fine particles of the basic molding material, which can be removed from the metal casting effortlessly and with as little residue as possible. If the molded part is a core, such advantageous disintegration properties lead to a particularly good removability of a metal casting.

In this context, it is also particularly desirable that the decomposition of the molded part, which is usually accompanied by thermal decomposition of the binder, is as emission-free as possible, i.e. without the emission of unpleasant smells and / or even substances that are hazardous to health, in order to minimize, reduce or ideally exclude any nuisance or health risks to the personnel working in the foundry. Such an impairment due to unpleasant smells and / or substances hazardous to health can occur especially when casting with the hot molten metal, in which case the feeders, which usually protrude from the mold, are the main cause, but also after the metal casting has solidified, when this is freed from the mold ("unpacked" or "demolded"). Various organic and inorganic binders are already known for the production of molded parts for the foundry industry, all of which have limitations or disadvantages typical of them.

In the field of organic binders and binder systems, those are known which can be cured by cold or hot processes. In the case of heat-curing processes, the molding material mixture is heated to a sufficiently high temperature, for example by the heated molding tool, in order to drive off the solvent contained in the binder and / or to cause a chemical reaction initiate by which the binder is cured. An example of such a thermosetting process is the so-called "hot box process". Today it is mainly used in the large-scale production of cores.

Cold-hardening processes are processes that are carried out essentially without heating the mold used for core production, usually. at room temperature or at a temperature caused by any, usually chemical, reaction. Curing is carried out, for example, by a gas which is passed through the molding material mixture to be hardened and thereby triggers a corresponding chemical reaction. An example of such a cold-hardening process is the so-called “cold box process”, which is used extensively in the foundry industry today.

According to the prior art, both hot-box processes and cold-box processes use organic binders based on phenolic resin. Irrespective of their exact composition, these have the disadvantage that, in the event of their desired decomposition, they are partly caused by the temperatures prevailing during metal casting. considerable amounts of pollutants such as Release benzene, toluene and xylene (also abbreviated "BTX"). In addition, the metal casting of such organic binders generally leads to undesirable odor and smoke or smoke emissions. In some such binder systems, undesirable emissions occur even during the manufacture and / or storage of the molded parts.

As an alternative to the aforementioned organic binders, corresponding inorganic binders are known which do not have the aforementioned phenomenon of releasing undesirable odors or pollutants during metal casting, or do so only to a much lesser extent. An example of such an inorganic binder is water glass. The corresponding molding material mixture essentially consists of molding material, for example quartz sand, and water glass (as an aqueous solution of alkali silicates). The shaped molding material mixtures are cured, for example, by gassing with CO ₂ .

However, the use of such inorganic binders is associated with other, typical disadvantages: moldings made from inorganic binders often have only low strengths. This is particularly evident immediately after the molded part has been removed from the tool. In addition, their often low moisture resistance leads to a limited shelf life of the manufactured products Molded parts. In addition, inorganic binders often do not have sufficient disintegration properties, which means that time-consuming reworking of the metal castings produced with corresponding molded parts is necessary. It is also known that waterglass-bound feeders generally have less good insulation properties than feeders bound with organic binders. Finally, inorganic binder systems such as water glass are also known for noticeably absorbing, ie consuming, thermal energy when casting metal, which causes the molten metal to solidify relatively early, so that casting errors can occur. This is especially true for iron and steel casting with the high casting temperatures required there. A number of organic binders as well as processes for the production of molded parts using such binders are already discussed in the prior art:

Document DE 10 2007 031376 A1 describes an alternative cold box process with crude oils.

Document DE 196 154 00 A1 describes a polymer, its use as a binder for the production of ceramic green bodies and a method for the production of ceramic objects.

JPH 061 57860 A describes water-resistant compositions.

In document JPS 61 276813 A curable compositions are given. Document EP 677 346 A2 relates to a casting process using a synthetic resin casting core, a synthetic resin core and a casting workpiece.

Document WO 96/26231 A1 describes a chemical binder comprising an ester-based polyol, an isocyanate and a catalyst.

Document WO 2011/044003 A2 relates to resins for cast sand based on lignite-urethane with improved performance.

The document WO 2017/071695 A1 describes phenol-formaldehyde resin-free binders for foundry molding sands. Document WO 2017/093371 A1 describes a method for producing refractory composite particles and feeder elements for the foundry industry, corresponding feeder elements and uses.

However, even in view of the prior art, there is still a need for a method for producing metallic castings or for producing hardened moldings for use in casting metallic castings, which realizes one, more and, ideally, all of the following advantageous properties: one high, at least sufficient for practical purposes, initial strength of the molded parts produced by the process; - A high final strength of the molded parts produced by the process; a high casting resistance or temperature resistance of the molded parts produced by the process; a clean or smooth surface of the molded parts produced by the process; - The highest possible moisture resistance or the highest possible water resistance of the molded parts produced by the process, so that among other things the best possible or long shelf life of the molded parts results even under different climatic conditions and / or these can be used with water-based sizes; - The lowest possible heat energy absorption and ideally a good heat insulation effect when casting metal from the molded parts produced by the process; the lowest possible emission of odors and / or pollutants as well as smoke or fumes of the molded parts produced by the process, in particular under the conditions of a metal casting, both when casting light metals and their alloys and when casting iron and steel; the at least partial use of renewable raw materials; the least possible expenditure on equipment when carrying out the method, in particular a feasibility (also) without heatable tools (that is to say can be carried out at least similar to a known cold box production method and with appropriate equipment). Furthermore, there is also a need for a binder for a molded part in the casting of metallic castings, which has or effects one, several and, ideally, all of the advantageous relevant properties specified above, and for a molding material mixture for use in such a process. Furthermore, there is also a need for a molded part which has one, more and, ideally, all of the relevant properties mentioned in connection with the method described above. There is also also a need for a binder that allows green-stable molded parts to be produced for use in the foundry industry, especially in the sense of flexible design of corresponding manufacturing processes.

It was therefore a primary object of the present invention to provide a method for producing a metallic casting or for producing a hardened molded part for use in casting metallic castings, which process provides one, more and, ideally, all of the above-mentioned advantageous Properties or has properties and a molding material mixture above all for use in the aforementioned method. It was a further object of the present invention to provide a binder for use in a molded part in the casting of metallic castings, which has or effects one, several and ideally all of the advantageous relevant properties indicated above.

A specific object of the present invention was also to provide a hardened molded part for use in the casting of metallic castings, which has one, several and ideally all of the relevant properties mentioned in connection with the method described above.

In addition, it was an object of the present invention to provide a binder which also makes it possible to produce molded parts which are stable on greenery for use in the foundry industry, if possible at room temperature. It has now surprisingly been found that the primary object and further objects and / or partial objects of the present invention are achieved by a method i) according to the invention for producing a metallic casting and / or ii) for producing a hardened molded part selected from the group consisting of a mold , Core and feeder, for use in casting metallic castings, with the following steps:

V1) Preparation of a molding material mixture comprising the following constituents (or consisting of the following constituents): a) at least one molding raw material, b) one or more aliphatic polymers, each comprising structural units of the formula I containing hydroxyl groups

c2) ein oder mehrere, vorzugsweise wasserdispergierbare und/oder aliphatische, Polyisocyanate, als Vernetzungsmittel für Hydroxygruppen des bzw. der aliphatischen Polymere; und d) Wasser; -CH ₂ -CH (OH) - (I), c) as hardener component, one or both components selected from the group consisting of: d) one or more biopolymers selected from the group of poly-D-glucosamines

c2) one or more, preferably water-dispersible and / or aliphatic, polyisocyanates, as crosslinking agents for hydroxyl groups of the aliphatic polymer or polymers; and d) water;

V2) shaping the molding material mixture, and then V3) hardening the molded molding material mixture or a resulting, non-hardened secondary product in one or more steps, so that a hardened molded part results.

The invention and combinations of preferred parameters, properties and / or components of the present invention which are preferred according to the invention are defined in the appended claims. Preferred aspects of the present invention are also specified or defined in the following description and in the examples.

With the method according to the invention, including its variants and preferred variants, hardened molded parts for the foundry industry can be produced, in particular molds, cores and feeders (insulating feeders and exothermic feeders, including feeder caps and feeder sleeves), which have a large number of advantageous properties. Depending on the design of the method (or its variants or the preferred variants), one, several or, ideally, all of the advantageous properties listed above can be achieved. All variants and configurations of the method according to the invention have in common that only low emissions of odor and / or pollutants as well as of smoke or smoke occur in them. In preferred embodiments of the method according to the invention, only very low emissions of odorous and / or pollutants as well as smoke or smoke occur. Furthermore, all variants and configurations of the method according to the invention have in common that the molded parts produced thereafter have little tendency to absorb thermal energy and exhibit advantageous quenching behavior.

In the above-mentioned process according to the invention, the molding material mixture in step V1) is preferably prepared by intensively mixing components a) to d) with one another in order to obtain a homogeneous distribution in the molding material mixture. The components are mixed with one another in a manner known per se, for example with a stirrer suitable for this purpose, for example a paddle stirrer. For preferred configurations of components a) to c) see below.

In step V2) the molding material mixture is formed into a three-dimensional structure, selected from the casting mold, core and feeder (including feeder caps and feeder sleeves). Step V2) is preferably carried out in a molding tool. In the context of the present invention, the term “molding tool” denotes any tool that can be used in the foundry industry for molding molded parts, preferably selected from the group consisting of casting mold, core and feeder (including feeder caps and feeder sleeves), in particular molded part boxes (including mold boxes and core boxes) and shooting machines for shooting molded parts, in particular core shooting machines.

If the molding in step V2) is carried out in a shooting machine, the ratio of total moisture content to total solids content in the molding material mixture is preferably adjusted before or during molding of the molding material mixture such that the molding material mixture can be fired in a shooting machine or in a molding box is stompable. This setting is readily possible for the person skilled in the art.

Step V3) of the method according to the invention specified above comprises hardening the molded molding material mixture or a non-hardened secondary product resulting therefrom, so that a hardened molded part results. Preferably, the hardening in step V3) results in an at least dimensionally hardened molded part. "Dimensionally stable" in this context means that a molded part with this property retains its shape in this way, also e.g. after removal of the molding tool, that it can be handled at least without loss or impairment of its shape and can be transported, for example, to a subsequent further processing site at the production site.

In the context of the present invention, the hardening of the shaped molding material mixture or a non-hardened secondary product resulting therefrom in step V3) comprises one, two or all three steps (in each case as far as applicable in a specific variant or configuration of the method according to the invention) selected from the group consisting of:

V31) Precipitation of at least portions of the one or more biopolymers (in the molded molding material mixture and / or the resulting, non-hardened secondary product), so that a green component is obtained (for further details see below),

V32) treatment of the shaped molding material mixture and / or of the resulting, not hardened secondary product and / or (if previously step V31) carried out ) of the molded part that is resistant to green standing by heating and / or removing water (for details see below), and

V33) Allowing hydroxy groups of the aliphatic polymer (s) of formula I (component b)) to crosslink with isocyanate groups of the polyisocyanates (component c1), if present), preferably the water-dispersible and / or aliphatic polyisocyanates, in the molded molding material mixture and / or in the resulting, non-hardened secondary product and / or in the green-proof molded part (if step V31 was carried out beforehand), so that a cross-linked molded part results as a hardened molded part (for details see below).

In the context of the present invention and in accordance with the customary understanding in the professional world, the term “green stability” means “dimensionally stable or dimensionally stable hardened or pre-hardened, but not yet hardened or hardened sufficiently for the intended purpose”. A green part that is stable on green has, for example, a hardness that is sufficient for removal from a molding tool or for transfer to a next processing step, but usually still does not have sufficient hardness for the ultimately intended purpose, here for use in the production of a metallic casting. The production of a green part that is stable in the green in the process according to the invention is preferred, for example, when the process is carried out without heatable molds: a green green stable part can then be treated further with or without the mold used for its production, in particular according to step V32) and / or step V33) of the method according to the invention, for example in a conventional drying oven. In order to produce a green part which is resistant to green standing in step V3) or V31), the presence of constituent c1), one or more biopolymers selected from the group of poly-D-glucosamines, in the molding material mixture is required by the process according to the invention. A green-stable molded part obtained after step V31) represents a hardened molded part in the sense of the present invention. In the preferred embodiments of the method according to the invention, wherein the hardening in step V3) comprises step V31), at least portions are, preferably the total amount of one or more biopolymers used in the process (preferably chitosan, see below for this) is precipitated from the aqueous proportions of the molded molding material mixture or a non-hardened secondary product resulting therefrom. This is preferably done in a manner known per se by increasing the pH of these aqueous fractions. The pH can be increased in any known manner, for example by adding aqueous alkali. The pH of the aqueous portions of the shaped molding material mixture or of an uncured secondary product formed therefrom is preferably increased by gassing with one or more alkaline compounds which are gaseous under the reaction conditions, preferably with one or more amines which are gaseous under the reaction conditions. The one or more of the several gaseous amines is preferably N, N, -dimethylpropyla- min. As a result of the increase in the pH value in the molded molding material mixture or the resulting, not hardened secondary product, which in each case contains the one or more biopolymers from the group of poly-D-glucosamines (preferably chitosan), at least portions of these biopolymers fail the aqueous constituents of the molded molding material mixture or the resulting, non-hardened secondary product, so that a green component is obtained. A molded part which is resistant to green standing can be produced in a manner known per se, in particular in accordance with the step of hardening or hardening a shaped molding material mixture (or a non-hardened secondary product resulting therefrom) in the cold box process: there This step can be carried out, for example, in a cold box tool which is known per se, in order to produce a green part which is resistant to green standing by the process according to the invention. A cold box core shooter without a heating device is suitable for this, without having to make any noteworthy changes to it, since in the cold box process, for example, the step of curing the molded molding material mixture (or the resulting, non-hardened secondary product) likewise preferably carried out by gassing with a gaseous amine. In the above-mentioned manner, green molds, cores and feeders which are stable in standing can be produced by the method according to the invention.

The shaped molding material mixture (as obtained after step V2)) and / or a non-hardened secondary product resulting therefrom and / or a green-stable molded part (as obtained after step V31)) is preferably further treated according to step V32) (see below). A molded part produced by the method according to the invention usually already has sufficient hardness for use in producing a metallic casting after step V32) has been carried out. Treating in step V3) or V 32) is obtained by heating the molded molding material mixture and / or the resulting, non-hardened secondary product and / or the green-resistant molded part, and / or by withdrawing water from the molded material mixture, secondary product or green-resistant molded part (as indicated above) ) as described in more detail below. As far as possible (ie if component c2), one or more polyisocyanates (as defined above or below or as preferred) is present as crosslinking agent for hydroxyl groups of the aliphatic polymer (s) in the molding material mixture in step V1) and is desired a (hardened) molded part obtained after step V31) and / or after step V32) in step V33) is further converted into a crosslinked (hardened) molded part, by crosslinking hydroxyl groups of the aliphatic polymer (s) of the formula I with isocyanate Groups of the aforementioned polyisocyanates. To produce a crosslinked molded part in step V3) or V33), the presence of constituent c2), one or more polyisocyanates (as defined above or below or defined as preferred) as crosslinking agent for hydroxyl groups of the or the is according to the inventive method aliphatic polymers, required in the molding material mixture.

The crosslinking of the hydroxyl groups with the isocyanate groups in step V33) is preferably carried out by heating the molded molding material mixture and / or the resulting uncured follow-up product and / or the green-resistant molded part and the, preferably simultaneous, removal of water therefrom, so that if step V32) is carried out accordingly and component c2) is present in the molding material mixture, the hydroxyl groups are at least partially crosslinked with the isocyanate groups (step V33)). In variants of the method according to the invention, in which step V3) comprises both step V32) and step V33), the product or end product of the method according to the invention therefore results in a crosslinked (hardened) molded part, which is a hardened molded part in the sense of the present invention. See below for details.

A cross-linked (hardened) molded part (as obtained after carrying out both steps V32) and step V33)) generally has sufficient hardness for use in the production of a metallic casting and additionally preferably has an advantageous high moisture resistance or high water resistance on. The initial strength, the final strength and the casting strength of such a crosslinked (hardened) molded part are generally particularly high. Preferred is a method according to the invention specified above, preferably a method (ii) according to the invention (preferably a method according to the invention designated above or below as preferred), wherein

- The molding material mixture as hardener component c) comprises (at least) component c1), one or more biopolymers selected from the group of poly-D-glucosamines, and preferably (additionally) component c2), one or more polyisocyanates (as above or defined below or defined as preferred), preferably (one or more) aliphatic polyisiocyanates, as crosslinking agents for hydroxy groups of the aliphatic polymer (s), and / or (preferably “and”)

- The hardening in step V3) includes

V31) (in the presence of component c1)) the precipitation of at least portions of the one or more biopolymers, preferably by increasing the pH of the aqueous portions of the molded molding mixture, particularly preferably by contacting, preferably gassing, with an alkaline gaseous compound, very particularly preferably by gassing with a gaseous amine, so that a green-stable molded part results; and / or (preferably "and")

V32) the treatment of the shaped molding material mixture and / or the resulting, non-hardened secondary product and / or (if step V31 was carried out beforehand) the molded part which is stable on green,

- by heating the molded molding material mixture and / or the resulting, not hardened secondary product and / or the green part which is stable on greenery, preferably to a temperature in the range of 100 ° C to 300 ° C, particularly preferably in the range from 150 ° C to 250 ° C and very particularly preferably in the range from 180 ° C to 230 ° C, and / or (preferably “and”)

- By removing water from the molded molding material mixture and / or from the resulting, not hardened secondary product and / or from the green-stable molded part.

In many cases, an embodiment of the method according to the invention specified above is also preferred, the molding material mixture as hardener component c) comprising only constituent c1), one or more biopolymers selected from the group of poly-D-glucosamines (ie comprising hardener component c) in this embodiment does not include component c2), one or more polyisocyanates). In this embodiment of the method according to the invention, which is preferred in many cases, step V31), the precipitation of at least portions of the one or more biopolymers, is preferably carried out to produce a green stand-resistant molded part. In this embodiment of the method according to the invention, step V32) is preferably carried out either with the shaped molding material mixture (as obtained after step V2), then without carrying out step V31 beforehand)) or - preferably - with the green part which is resistant to green (as obtained after step V31), then carried out in addition to and after the previous step V31)). The removal of water in step V32) (in all variants of the method according to the invention, which include step V32) and the removal of water) is selected by one, two or by all three measures from the group consisting of:

Freeze-drying the molded molding material mixture and / or the resulting, not hardened secondary product and / or the green-resistant molded part, - vacuum drying the molded molded material mixture and / or the resulting uncured secondary product and / or the green-stable molded part, and

Heating the molded molding material mixture and / or the resulting, non-hardened secondary product and / or the green part which is stable on greenery (and Removal of water from the molded molding material mixture and / or from the resulting, non-hardened secondary product and / or from the green part which is stable on greenery; executed. Preferably, the removal of water in step V32) (in all variants of the method according to the invention, which include step V32) and the removal of water) is carried out by heating the molded molding material mixture and / or the resulting uncured secondary product and / or the green-stable molded part and (preferably simultaneous) removal of water from the molded molding material mixture and / or from the non-hardened secondary product resulting therefrom and / or from the green-stable molded part.

Also preferred is an embodiment of the method according to the invention specified above, preferably a method according to the invention (ii) (preferably a method according to the invention designated above or below as preferred), the molding material mixture as hardener component c) only comprising component c1), one or more biopolymers selected from the group of poly-D-glucosamines and which, in addition to and after step V31) defined above, comprises the step:

V32) the treatment of the green-stable molded part,

- by heating the molded part which is stable on green, preferably to a temperature in the range from 100 ° C. to 300 ° C., particularly preferably in the range from 150 ° C. to 250 ° C. and very particularly preferably in the range from 180 ° C. to 230 ° C. , and / or (preferably "and")

- by removing water from the molded part that is stable against greenery. In a further, particularly preferred embodiment of the process according to the invention, the molding material mixture comprises, as hardener component c), both component c1), one or more biopolymers selected from the group of poly-D-glucosamines, and additionally component c2), one or more Polyisocyanates (as defined above or defined below or as preferred). In this embodiment, molded parts with particularly advantageous properties can be produced, in particular molded parts with a particularly high moisture resistance or a particularly high water resistance as well as with a particularly high initial strength, a particularly high final strength and a particularly high casting strength.

In the aforementioned, particularly preferred embodiment of the process according to the invention, in which the molding material mixture as hardener component c) comprises both component d) and additionally component c2), the polyisocyanates of component c2) are preferably selected from the group consisting of: aromatic Polyisocyanates, preferably water-compatible aromatic polyisocyanates, particularly preferably water-dispersible aromatic polyisocyanates, aliphatic polyisocyanates, preferably water-dispersible aliphatic polyisocyanates, particularly preferably the preferred aliphatic polyisocyanates and mixtures thereof, which are described in more detail below.

Particularly preferred as hardener component c2) in the process according to the invention described above or below (or in a preferred process according to the invention described above or below) (if hardener component c2) is used or is present) are water-dispersible polyisocyanates, preferably selected from the group consisting of water-dispersible aromatic polyisocyanates, water-dispersible aliphatic polyisocyanates and mixtures thereof. Water-dispersible aliphatic polyisocyanates are very particularly preferred as hardener component c2) in the process according to the invention described above or below (or in a preferred process according to the invention described above or below) (if hardener component c2) is used or is present.

Water-dispersible polyisocyanates are known per se in the field, inter alia from WO 2011/144644 A1 or from the product brochure “The Chemistry of Polyurethane Coatings”, Bayer MaterialScience LLC (08/05). They are characterized by their property from being able to act as a crosslinker, especially as a crosslinker of non-aqueous hydroxyl groups such as alcoholic hydroxyl groups, even in aqueous or water-containing medium. In contrast, the aromatic polyisocyanates used according to the prior art in the foundry industry, for example as cold box binders, cannot be used in the desired manner in aqueous or water-containing media because of the high reactivity of their isocyanate functions, as is the case with a combination with aliphatic polymers, each comprising hydroxyl-containing structural units (in particular polyvinyl alcohol), but is advantageous or even necessary.

Particularly preferred as hardener component c2) in the process according to the invention described above or below (or in a preferred process according to the invention described above or below) (if hardener component c2) is used or is present) water-dispersible polyisocyanates are those water-dispersible polyisocyanates which do the following fulfill the specified selection criterion: The water-dispersible polyisocyanate forms in contact with water within

24 hours a fluid that does not show any solid particles with the eye without optical aids. To check whether a polyisocyanate is water-dispersible, 100 mg of the polyisocyanate (preferably in the form of a 100 μm thick film) are added to 100 ml of water (at 20 ° C.) and shaken on a commercially available shaking table for 24 hours. If after shaking no more solid particles can be seen, but the fluid has a cloudiness (which can be seen with the eye without optical aids), the polymer is water-dispersible.

Aromatic polyisocyanates (as indicated above) have the advantage that they can be crosslinked with the structural units of the formula I which contain hydroxyl groups in each case and are therefore well suited for the production of moldings with high moisture resistance. However, the use of aromatic polyisocyanates is not particularly advantageous if the production of hardened molded parts in the foundry industry is based on working with as little emissions as possible and generating as few odors and / or pollutants as possible when using aromatic polyisocyanates such undesirable emissions occur more often. In the context of the present invention, the term “aromatic polyisocyanates” is understood to mean polyisocyanates which contain organic, aromatic rings (ie aromatic hydrocarbons as structural components). In all variants of the process according to the invention in which component c2) is used in step V1), the polyisocyanates of component c2) therefore preferably comprise aliphatic polyisocyanates, particularly preferably water-dispersible aliphatic polyisocyanates and very particularly preferably the preferred aliphatic polyisocyanates described below. Because of their reduced reactivity compared to aromatic polyisocyanates, aliphatic polyisocyanates are substantially better suited for use in aqueous or water-containing medium than aromatic polyisocyanates. The abovementioned aliphatic polyisocyanates, water-dispersible aliphatic polyisocyanates or the (defined below) preferred aliphatic polyisocyanates preferably make up a proportion of> 75% by weight in these preferred variants of the process according to the invention (in which component c2) is used in step V1). %, particularly preferably from> 90% by weight and very particularly preferably from> 95% by weight, based on the total mass of the one or more polyisocyanates used (or present) in the molding material mixture. In a particularly preferred variant of this embodiment of the process according to the invention, the polyisocyanates of component c2) comprise only (ie 100% by weight, based on the total mass of the one or more polyisocyanates used or present in the molding material mixture), preferably aliphatic polyisocyanates only water-dispersible aliphatic polyisocyanates and particularly preferably only the preferred aliphatic polyisocyanates described below.

Aliphatic polyisocyanates have the advantage that they contribute even less to the occurrence of undesirable emissions of odors and / or pollutants and of smoke or fumes when carrying out the process according to the invention than, for example, aromatic (i.e. containing organic, aromatic rings) polyisocyanates. Accordingly, a method according to the invention specified above is also preferred, preferably a method (ii) according to the invention (preferably a method according to the invention designated above or below as preferred), wherein

component c2) of the molding material mixture (if used or present) comprises one or more water-dispersible polyisocyanates or consists of one or more water-dispersible polyisocyanates, or - The one or more polyisocyanates (of component c2), if used or present) comprise one or more water-dispersible polyisocyanates or the one or more polyisocyanates (of component c2), if used or available) are one or more water-dispersible polyisocyanates. In the particularly preferred embodiment of the process according to the invention, in which the molding material mixture as hardener component c) comprises both constituent c1) and additionally constituent c2), step V31), the precipitation of at least portions of the one or more, is preferably used to produce a green-resistant molded part several biopolymers. If step V32) is carried out in this embodiment of the method according to the invention, this is carried out either with the molded molding material mixture and / or with the resulting, non-hardened secondary product (as obtained after step V2)), or this is preferably carried out additionally after carrying out of step V31), carried out with the green part. The removal of water in step V32) can then be carried out by one, by two or by all three of the measures mentioned above (freeze drying, vacuum drying, heating).

In the particularly preferred embodiment of the method according to the invention, in which the molding material mixture as hardener component c) comprises both component c1) and component c2), step V33) is preferably carried out in addition to step V32) (and preferably simultaneously with this) . The crosslinking of hydroxyl groups and isocyanate groups in step V33) to produce the crosslinked molding preferably comprises:

- heating the molded molding material mixture and / or the resultant uncured secondary product and / or the green part which is resistant to green standing, preferably the green part which is stable to green standing, preferably to a temperature in the range from 100 ° C. to 300 ° C., particularly preferably in the range from 150 ° C to 250 ° C and very particularly preferably in the range of 180 ° C to 230 ° C, and the removal of water from the molded molding material mixture and / or from the resulting uncured secondary product and / or from the green-resistant molded part, preferably from the green-stable molded part; The hardening in step V3) of the method according to the invention therefore also includes step V33) (as defined above) in this case in addition to step V32).

As mentioned above, a molded molding material mixture produced by the method according to the invention and / or a non-hardened follow-up product resulting therefrom can be converted into the hardened molded part or to the crosslinked (hardened) molded part as well as a green-stable molded part produced according to the method according to the invention. I.e. Step V32) can be carried out according to the method according to the invention after step V2) or after step V31). Conversely, however, it is not preferred to carry out step V31) after step V32), since a precipitation of at least portions of the one or more biopolymers in the molded molding material mixture and / or in the resulting uncured follow-up product (in step V31)) after it has been heated or after water has been removed from it or from it, this is generally not technically expedient or not possible.

In a variant of the method according to the invention, to carry out step V32) (and preferably additionally or simultaneously from step V33)), a shaped molding material mixture (produced in step V2) and / or a non-hardened secondary product resulting therefrom is generally heated together with the molding tool (for example a molding box or a shooting head), in a drying device, for example a drying oven, a belt dryer, a continuous dryer, a tunnel dryer or a drying belt, or also by passing a heated gas, preferably heated air, through the shaped molding material mixture to a temperature indicated above, and preferably - particularly preferably at the same time - removes water from the molded molding material mixture and / or from the resulting, non-hardened secondary product. In this process variant, a drying oven is preferably used as the drying device, particularly preferably a circulating air drying oven. The hardened molded part can then usually be removed from the mold (if present or still available).

In another variant of the method according to the invention, to carry out step V32) (and preferably additionally or simultaneously from step V33)), a green-stable molded part produced by the method according to the invention is heated, either together with the molding tool (for example a molding box or a shooting head) or preferably without the molding tool, in a drying device, for example a drying oven, a belt dryer, a continuous dryer, a tunnel dryer or a drying belt, to a temperature specified above, and preferably - and particularly preferably at the same time - removes water from the green-shaped molded part. In this variant of the method, too, a drying oven is preferably used as the drying device, particularly preferably a circulating air drying oven.

The advantage of this last-mentioned process variant lies above all in the fact that the green-stable molded part does not have to be converted into the hardened molded part (in particular to the cross-linked, hardened molded part) in a mold and in particular not in a heatable mold, but instead (for example at room temperature) from the mold removed and implemented separately in a suitable drying device (in particular by heating and removing water as described above) to give the hardened molded part (in particular the crosslinked molded part). In this way, non-heatable molding tools, such as cold box core shooters known per se, can be used for molding the molding material mixture or the resulting, not hardened secondary product and / or for producing the molded part which is stable on green, so that, for example, According to the process variant according to the invention, no complex and costly conversions to production sites equipped for cold box processes are necessary. However, since the implementation of this variant of the method is not limited to the implementation in molds which cannot be heated, it can be carried out at production sites equipped with different apparatuses, so that the further advantages of the method according to the invention can be used very flexibly in industry .

In general, the setting of the exact process parameters of the process according to the invention in step V32) and / or in step V33), for example the duration of the heating, the temperature of the drying oven or of the heated gas, the flow time with heated gas (ie the duration of the passage of the heated gas) Gas) and the pressure of the heated gas (if used) to a large extent depending on the properties of the molded part to be produced by curing, such as its size, its weight, its volume or its wall thickness. If necessary, the parameters suitable in the individual case can be determined by the skilled person in preliminary tests in a manner known per se.

Also preferred is a method according to the invention specified above, preferably a method (ii) according to the invention (preferably a method according to the invention designated above or below as preferred), wherein the molding material mixture as hardener component c) comprises (at least) component c2), one or more polyisocyanates (as defined above or below or defined as preferred), preferably (one or more) aliphatic polyisocyanates, and preferably additionally component c1), one or more biopolymers selected from the group of poly-D-glucosamines, comprises and / or

- The hardening in step V3) comprises at least

V32) the treatment of the shaped molding material mixture and / or the resulting, not hardened secondary product and / or (in the presence of the

Component c1) and previous execution of step V31)) of the green stand-proof molded part,

- by heating the shaped molding material mixture and / or the resulting, not hardened secondary product and / or the green part which is resistant to green growth, preferably to a temperature in the range from 100 ° C. to 300 ° C., particularly preferably in the range from 150 ° C. to 250 ° C. ° C and very particularly preferably in the range from 180 ° C to 230 ° C, and / or (preferably “and”) - by removing water from the molded molding material mixture and / or from the resulting uncured subsequent product and / or from the green stand-resistant molded part, and (in addition to step V31) and / or V32), preferably in addition to step V32)) preferably V33), the crosslinking of hydroxyl groups of the aliphatic polymer (s) of the formula I with isocyanate groups of the polyisocyanates (as above or defined below or defined as preferred), in the molded molding material mixture and / or in the resulting, non-hardened secondary product and / or in the green-resistant molded part, so that a crosslinked molded part results as a hardened molded part. In many cases, an embodiment of the preferred method according to the invention specified above is also preferred, the molding material mixture as hardener component c) comprising only the hardener component c2), one or more polyisocyanates (as defined above or below or defined as preferred) (ie the hardener component c ) does not include component c1) in this embodiment, one or more biopolymers selected from the group of poly-D-glucosamines):

In this embodiment of the process according to the invention, in which the molding material mixture as hardener component c) comprises only component c2) (but not component c1)), the polyisocyanates of component c2) preferably comprise a proportion of> 75% by weight, particularly preferably of > 90% by weight and very particularly preferably of> 95% by weight of aliphatic polyisocyanates, preferably of water-dispersible aliphatic polyisocyanates and particularly preferably of aliphatic polyisocyanates to be used according to the invention (specified above and defined in more detail below), based on the total mass of the one or more polyisocyanates of component c2) used (or present) in the molding material mixture. In a particularly preferred variant of this embodiment of the process according to the invention, the polyisocyanates of component c2) comprise only aliphatic polyisocyanates, preferably only water-dispersible aliphatic polyisocyanates, particularly preferably only the preferred aliphatic polyisocyanates described below, as component c2). In this preferred embodiment of the process according to the invention (in which the molding material mixture comprises only component c2) as hardener component c), no molded part which is stable on green is produced.

In the preferred embodiment of the method according to the invention, in which the molding material mixture as hardener component c) comprises only component c2) (but not component c1)), step V32) and preferably additionally (and preferably simultaneously with step V32)) step V33) are carried out in each case carried out analogously or correspondingly as stated above for the design of the process, in which the molding material mixture as hardener component c) comprises both component c1) and component c2) includes. Step V32) is carried out in each case with the shaped molding material mixture (as obtained after step V2)) or with a resultant, non-hardened follow-up product (but not with a molded part which is green-proof).

For the particularly preferred embodiment of the process according to the invention, in which the molding material mixture as hardener component c) comprises both component c2), one or more polyisocyanates (as defined above or below or defined as preferred), and additionally component c1), one or more biopolymers selected from the group of poly-D-glucosamines, see above.

It is therefore preferred a method according to the invention specified above i) for producing a metallic casting and / or ii) for producing a hardened molded part selected from the group consisting of casting mold, core and feeder, for use in the casting of metallic castings, (preferably one above or the process according to the invention designated below as preferred), comprising the following steps: V1) producing a molding material mixture comprising the following constituents: a) at least one molding raw material, b) one or more aliphatic polymers, each comprising structural units of the formula I containing hydroxyl groups

-CH ₂ -CH (OH) - (I), c) as hardener component, both constituents selected from the group consisting of: d) one or more biopolymers selected from the group of poly-D-glucosamines and c2) one or more polyisocyanates ( as defined above or below or as preferred), preferably aliphatic polyiso cyanates, particularly preferably water-dispersible aliphatic polyisocyanates, as crosslinking agents for hydroxyl groups of the aliphatic polymer (s);

d) water;

V2) shaping the molding material mixture, and then

V3) curing the molded molding material mixture or a non-hardened secondary product resulting therefrom, the curing in step V3) comprising V31) the precipitation of at least portions of the one or more biopolymers, preferably by increasing the pH of the aqueous portions of the molded molding material mixture, particularly preferably by contacting, preferably gassing, with an alkaline-reacting gaseous compound, very particularly preferably by gassing with a gaseous amine, so that a molded part which is green-resistant results; and / or (preferably "and")

V32) the treatment of the shaped molding material mixture and / or of the resulting, not hardened secondary product and / or the green part that is resistant to green standing, preferably the green part that is stable to green standing (according to the previous one)

Execution of step V31)),

- by heating the molded molding material mixture and / or the resulting, not hardened secondary product and / or the green part that is resistant to green standing (preferably the green part that is stable to green standing), preferably to a temperature in the range from 100 ° C. to 300 ° C, particularly preferably in the range from 150 ° C to 250 ° C and very particularly preferably in the range from 180 ° C to 230 ° C, and / or (preferably “and”)

- By removing water from the molded molding material mixture and / or from the resulting, not hardened secondary product and / or from the green-proof molded part (preferably from the green-proof molded part), and (in addition to step V31) and / or V32), preferably additionally to step V32)), preferably V33), the crosslinking of hydroxyl groups of the aliphatic polymer (s) of the formula I with isocyanate groups of the (used) polyisocyanates in the molded molding material mixture and / or in the resulting, non-hardened secondary product and / or in the green-proof molded part (preferably in the green-proof molded part), so that a cross-linked molded part results as a hardened molded part.

It has been shown in our own experiments that the (crosslinked) hardened moldings produced (ie according to the variant, of the process according to the invention) prepared and crosslinked according to the particularly preferred variant of the process according to the invention specified above, and in which the molding material mixture comprises components c1) and c2) step V32) comprises heating and removing water and both steps V32) and V33) are carried out) a high initial strength, a particularly high final strength (after hardening or crosslinking) as well as a particularly high casting strength and a particularly high temperature resistance during the Have castings with iron or steel. Also noticeable is the advantageous smooth and clean surface structure of these (crosslinked) hardened molded parts produced according to the particularly preferred variant of the method according to the invention specified above. Furthermore, it was also possible to show that the (crosslinked) hardened moldings produced according to this particularly preferred variant of the process according to the invention given above have particularly good moisture resistance and water resistance, which makes them excellent for long storage over days or weeks even under difficult conditions Suitable climatic conditions (humid-warm climate) are. In the case of metal casting, the (crosslinked) hardened moldings produced according to this particularly preferred variant of the process according to the invention indicated above also show only a low absorption of thermal energy, which results in a small formation of voids, which also only occurs in the actual metal casting. areas of the metal casting (for example in the feeder neck) that are far away from the surface. This property also makes this variant of the method according to the invention particularly suitable for the production of feeders, in particular of insulating feeders. After metal casting has taken place, the (crosslinked) hardened molded parts produced in accordance with this variant of the process according to the invention are also distinguished by an extraordinarily advantageous unpacking behavior, since they largely disintegrate due to the heat released during metal casting and thus further processing of the correspondingly produced metal Simplify the casting considerably because only a few or, ideally, no further processing steps are required on the metal casting produced. A particular advantage of the molded parts produced by the process according to the invention is their emission behavior, especially during metal casting and when unpacking metal castings which have been produced with the aid of these molded parts produced according to the invention: in metal casting with light metals or their alloys (for example in aluminum casting) as well as in iron or steel casting or when unpacking the correspondingly produced metal castings hardly any smoke or. Smoke formation, hardly any occurrence of unpleasant smells and / or hardly any emissions of potentially health-endangering substances are observed, as they occur regularly when using conventional, especially aromatic-containing (such as aromatic polyols and aromatic polyisocyanates) organic foundry binders. This applies in particular to feeders produced using the method according to the invention. Insulating feeders produced by the method according to the invention (in particular according to its preferred variants) show hardly any undesirable emissions, even at the relatively low temperatures of the light metal casting. Exothermic feeders produced by the method according to the invention show hardly any undesirable emissions (such as smoke development) even during or after the combustion. Particularly low smoke or smoke formation, particularly low occurrence of unpleasant odors and / or particularly low emissions of substances which are potentially hazardous to health are observed if predominantly or exclusively aliphatic polyisocyanates are used as component c2) in the process according to the invention. the, preferably the aliphatic polyisocyanates designated as preferred in this text, and / or if at best small amounts and preferably no further aromatics-containing constituents are used in the process according to the invention.

Also preferred is a method according to the invention given above, preferably a method according to the invention (ii) (preferably a method according to the invention mentioned above or below as preferred), the aliphatic polymers used being capable of producing structural units of the formula I comprising hydroxyl groups by at least partial saponification of polyvinyl acetate; and or

- are selected from the group consisting of polyvinyl alcohols, polyvinyl acetates and mixtures thereof; and or

-> 75% by weight, preferably> 90% by weight, particularly preferably> 98% by weight, of the total mass of the molding material mixture, in addition to the one or more biopolymers used as component d), selected from the group of poly- D-glucosamines, total organic polymers comprising hydroxyl groups used; and / or - comprise one or more polyvinyl alcohols, the entirety of the polyvinyl alcohols used preferably

has a degree of hydrolysis of> 50 mol% (ie in the range from 50.1 mol% to 100 mol%), preferably determined according to the method as specified in document DE 10 2007 026 166 A1, paragraphs [0029] to [ 0034], and particularly preferably has a degree of hydrolysis in the range from 70 mol% to 100 mol%, very particularly preferably in the range from 80 mol% to 100 mol%, preferably determined according to the method according to DIN EN ISO 15023-02 2017-02 Draft, Appendix D, and / or

has a dynamic viscosity in the range from 0.1 to 30 mPas, preferably in the range from 1.0 to 15 mPas, particularly preferably in the range from 2.0 to 10 mPas, each determined at a 4% -igen (w / w) aqueous solution of all of the polyvinyl alcohols used at 20 ° C according to DIN 53015: 2001-02; and or

-> 75% by weight, preferably> 90% by weight, particularly preferably> 98% by weight, of the total mass of the aliphatic polymers used overall in the molding material mixture each comprising structural units of the formula I containing hydroxyl groups.

In a preferred embodiment of the process according to the invention, the aliphatic polymers to be used are in each case fully (ie 100% by weight) structural units of the formula I containing hydroxyl groups as one or more polyvinyl alcohols. The molding material mixture produced in step V1) of the process according to the invention comprises, as organic polymers comprising hydroxyl groups, constituents b), one or more aliphatic polymers each comprising structural units of formula I comprising hydroxyl groups, and (if present or used) c1), one or more biopolymers selected from the group of poly-D-glucosamines. In the process according to the invention, the constituents b) and (if present or used) d) preferably make> 95% by weight, particularly preferably> 98% by weight, of the total mass in the molding material mixture as a whole in the molding material mixture prepared in step V1) used organic, comprising hydroxy groups, organic compounds. In a particularly preferred variant of the process according to the invention, constituents b) and (if present) make in the molding material mixture produced in step V1) d) 100% by weight of the total mass of the organic compounds comprising hydroxyl groups to be used in total in the molding material mixture.

According to the invention, it is preferred to use the one or more aliphatic polymers each comprising hydroxyl group-containing structural units of the formula I (component b)) for producing or in the preparation of the molding material mixture in step V1) at least partially and preferably completely as an aqueous mixture comprising one or more aliphatic polymers each comprising hydroxyl-containing structural units of the formula I. This aqueous mixture preferably comprises the one or more aliphatic polymers in a total amount (concentration) in the range from 10% by weight to 40% by weight, particularly preferably in the range from 15% by weight .-% to 35 wt .-% and very particularly preferably in the range of 20 wt .-% to 30 wt .-%, based on the total mass of the aqueous mixture comprising one or more aliphatic polymers. Preferably, the one or more aliphatic polymers used, each comprising hydroxyl-containing structural units of the formula I, preferably the one or more polyvinyl alcohols, in the said aqueous mixture are> 90% by weight, preferably> 95% by weight, based on the Total mass of one or more aliphatic polymers used, dissolved before. It has been shown that the one or more aliphatic polymers specified above, in particular the one or more polyvinyl alcohols specified above as preferred, make a significant contribution to the advantageous properties of the hardened moldings produced according to the invention. In particular, the abovementioned one or more aliphatic polymers contribute to the good moisture resistance or water resistance, final strength and cast resistance of the hardened moldings produced according to the invention.

Apparently, the above-mentioned one or more aliphatic polymers, in particular the above-mentioned one or more polyvinyl alcohols, also make a significant contribution or are even the cause of the advantageous low emission properties of the hardened molded parts produced by the process according to the invention or its preferred variants. in particular for the low or very low emission of smoke or smoke and / or of odors and / or pollutants during or after the metal casting and the low or very low Emission of odors and / or pollutants during the manufacture or storage of the hardened molded parts. This is probably due to the fact that the aliphatic polymers to be used according to the invention contain practically no or no aromatic constituents, which are frequently cited as the cause of harmful emissions. The one or more aliphatic polymers to be used according to the invention are therefore preferably free from aromatics-containing constituents and / or other constituents which, under the conditions of the method according to the invention, cause significant amounts of smoke, smoke, odor and / or pollutant emissions.

For the reasons given above, the process according to the invention is preferably not carried out in the presence of aromatic-containing organic compounds or the molding material mixture produced in the process according to the invention is aromatic-free (ie contains the molding material mixture produced in the process according to the invention and also the ones used for its production Ingredients preferably do not contain any aromatic compounds containing organic compounds). The molding material mixture prepared in step V1) preferably also does not contain any structural units of the formula I (constituent b)) which contain hydroxyl groups and which comprise the one or more aliphatic polymers and the one or more polyisocyanates, as crosslinking agents for hydroxyl groups of the or the aliphatic polymer active compound, selected from the group consisting of organotin compounds, organoaluminum compounds, dimethylcyclohexylamine, N-substituted pyrrolidones, N-substituted imidazoles, triazine derivatives, diazabicyclooctane or quaternary ammonium salts (as indicated in WO 2017/071695 A1).

Also preferred is a method according to the invention specified above, preferably a method (ii) according to the invention (preferably a method according to the invention designated above or below as preferred), wherein

- The one or one or more of the several (or all) biopolymers selected from the group of poly-D-glucosamines comprise chitosan, the chitosan preferably has a degree of deacetylation of> 70 mol%, preferably of> 75 mol% and particularly preferably of> 80 mol%, determined by means of ¹ H-NMR spectroscopy, and / or - a dynamic viscosity of> 500 mPa · s , preferably of> 600 mPa s, particularly preferably of> 700 mPa · s, each determined using a 1% (w / w) solution of the chitosan in 1% (w / w) acetic acid at 20 ° C DIN 53015: 2001-02, and / or - the ratio of the sum

- The total mass of the aliphatic polymers used each comprising hydroxyl-containing structural units of the formula I and the total mass of biopolymers used selected from the group of poly-D-glucosamines for

- Total mass of the molding material used, is in the range from 0.2: 100 to 13: 100, preferably in the range from 0.3: 100 to 10: 100, particularly preferably in the range from 0.5: 100 to 9: 100.

In the embodiment of the process according to the invention specified above, the chitosan to be used preferably has a degree of deacetylation in the range from 65 mol% to 95 mol%, particularly preferably in the range from 70 mol% to 95 Mol%, very particularly preferably in the range from 75 mol% to 95 mol% and very preferably in the range from 80 mol% to 95 mol%.

In the embodiment of the method according to the invention specified above, the chitosan to be preferably used preferably has a dynamic viscosity in the range from 500 mPa · s to 1100 mPa · s, particularly preferably in the range from 600 mPa · s to 800 mPa · s, very particularly preferably in the range from 700 mPas to 800 mPas and most preferably in the range from 720 mPas to 770 mPas, each determined on a 1% (w / w) solution of the chitosan in 1% (w / w) acetic acid at 20 ° C according to DIN 53015: 2001-02 (determined with the falling ball viscometer according to Höppler). It has been shown that the above-mentioned preferred biopolymers selected from the group of poly-D-glucosamines, in particular the above-mentioned preferred chitosan, are particularly suitable for producing a molding material mixture in combination with the further constituents to be used according to the invention by the process according to the invention, which can first be converted in step V31) to a green part which is stable on the green and then by further treatment in step V32) and preferably additionally in step V33) in a hardened shaped part (or in a crosslinked, hardened shaped part) which has the above-mentioned has advantageous properties. The use of biopolymers selected from the group of poly-D-glucosamines also opens up the possibility, at least in part, of using renewable raw materials to produce hardened molded parts for use in the foundry industry.

According to the invention, it is also preferred to use the one or more biopolymers selected from the group of the poly-D-glucosamines (component c1)), if present or used, at least partially and preferably completely, to prepare the molding material mixture in step V1) as an aqueous preparation comprising one or more biopolymers selected from the group of poly-D-glucosamines. The aqueous preparation to be used in the process according to the invention preferably comprises the one or more biopolymers selected from the group of poly-D-glucosamines in a total amount (concentration) in the range from 0.5% by weight to 10% by weight, particularly preferably in the range from 1% by weight to 7.5% by weight and very particularly preferably in the range from 1.5% by weight to 5% by weight, based on the total mass of the aqueous preparation, comprising one or more biopolymers . The aqueous preparation can additionally be used to partially or completely dissolve the one or more biopolymers suitable amount of one or more suitable acids. The aqueous preparation preferably comprises up to 5% by weight, particularly preferably up to 2.5% by weight, based on the total mass of the aqueous preparation, of one or more acids, selected from the acids which have a pKa value in the Range from 3 to 7, preferably in the range from 3.5 to 6.5 and preferably contain no aromatic organic compounds or residues. Particularly preferably, said one or more acids are one or more organic acids, preferably one or more single-proton organic acids. The one or at least one of the said acids is very particularly preferably acetic acid. The one or more biopolymers used, selected from the group of the poly-D-glucosamines, preferably chitosan, are preferably present in the aqueous preparation in question in an amount of> 90% by weight, preferably> 95% by weight, based on the solution Total mass of biopolymers used selected from the group of poly-D-glucosamines. Also preferred is a method according to the invention specified above, preferably a method (ii) according to the invention (preferably a method according to the invention designated above or below as preferred), component c2) of the molding material mixture (if used or present) one or more aliphatic polyisocyanates, preferably one or more water-dispersible aliphatic polyisocyanates.

It is also preferred to use a method according to the invention, preferably a method (ii) according to the invention (preferably a method according to the invention described above or below as preferred), the one or more polyisocyanates used (if used) as component c2) in step V1) or present) (one or more) aliphatic polyisocyanates (preferably in the sense of the aliphatic polyisocyanates specified in the preceding and the following text, which should preferably be used in the process according to the invention), preferably (one or more) water-dispersible aliphatic polyisocyanates, preferably - the one or one or more or all of the several aliphatic polyisocyanates are nonionically or ionically hydrophilized, and or

- The one or one or more or all of the several aliphatic polyisocyanates comprises or comprise a polyether group or a sulfonate group, and / or - The one or one or more or all of the several aliphatic polyisocyanates comprises a polyether group and also a urethane and / or comprises an allophanate group, and / or

- The one or one or more or all of the several aliphatic polyisocyanates comprises or comprise one or more 2,4,6-trioxotriazine groups and preferably comprises or comprises a polyether group or a sulfonate group, preferably a polyether group, and / or

- The one or one or more or all of the several aliphatic polyisocyanates comprise one or more 2,4,6-trioxotriazine groups and a polyether group and also a urethane and / or an allophanate group, preferably a urethane group, and / or

- The one or one or more or all of the several aliphatic polyisocyanates comprise self-emulsifying and / or self-water-emulsifiable aliphatic polyisocyanates, and / or the one or more aliphatic polyisocyanates used> 50% by weight, preferably> 75% by weight, particularly preferably> 90% by weight and very particularly preferably> 98% by weight, of the one or all used in the molding material mixture make up several polyisocyanates. The aliphatic polyisocyanates which are preferably described or defined above in the process according to the invention are also water-dispersible aliphatic polyisocyanates for the purposes of the present invention.

In a preferred embodiment of the preferred variant of the process according to the invention specified above, the one or more aliphatic polyisocyanates used (preferably the aliphatic polyisocyanates specified above or below as the preferred aliphatic polyisocyanates to be used in the process according to the invention) make up 100% by weight of the total mass of the the molding material mixture used in total one or more polyisocyanates.

The above-mentioned one or more polyisocyanates to be used according to the invention, preferably the one or more aliphatic polyisocyanates to be preferably used according to the invention, are preferably those with at least two free isocyanate groups, so that they form structural units containing hydroxyl groups for crosslinking with free hydroxyl groups of the aliphatic polymers of formula I are suitable. The above-mentioned one or more aliphatic polyisocyanates to be used according to the invention or preferably to be used according to the invention preferably comprise aliphatic and / or cycloaliphatic polyisocyanates. The aliphatic polyisocyanates to be used according to the invention or preferably to be used according to the invention preferably do not contain any aromatic groups (ie are free of aromatics), for the reasons given above (avoidance of smoke, smoke, odor and / or pollutant emissions by the molded parts produced by the process according to the invention, better water compatibility or water dispersibility).

The one or more aliphatic polyisocyanates preferably designated or defined above and preferably to be used according to the invention are self-emulsifying or self-water-emulsifiable aliphatic polyisocyanates, as described, for example, in the book by Ulrich Meier-Westhues: "Polyurethanes - Varnishes, Adhesives and Sealants", Hanover: Vincentz Network 2007 (ISBN: 3-86630-896-5 or 978-3-86630-896-1), pp. 43-46.

The one or more aliphatic polyisocyanates specified or defined above and to be used according to the invention preferably include aliphatic polyisocyanates selected from the group consisting of: nonionically hydrophylated aliphatic polyisocyanates of the polyether urethane type, for example Bayhydur® 3100, Bayhydur® VP LS 2306, Desmodur® DA -L and Desmodur® DN non-ionically hydrophylated aliphatic polyisocyanates of the polyether allophanate type, for example Bayhydur® 304 and Bayhydur® 305 and ionically hydrophilized aliphatic polyisocyanates of the sulfonate type, for example Bayhydur® XP 2487/1, Bayhydur® XP 2547, Bayhydur® XP 2570 and Bayhydur® XP 2655. One or more aliphatic polyisocyanates to be used with particular preference in the process according to the invention are selected from the group consisting of nonionically hydrophylated aliphatic polyisocyanates of the polyether urethane type, for example Bayhydur® 3100, Bayhydur® VP LS 2306, Desmodur® DA-L and Desmodur® DN. Desmodur® DA-L (CAS RN 125252-47-3) is a very particularly preferred aliphatic polyisocyanate to be used in the process according to the invention.

It has been shown that the preferred self-emulsifying or self-water-emulsifiable aliphatic polyisocyanates described above are extremely suitable under the conditions of the process according to the invention as crosslinking agents for the structural units of the formula I, each comprising hydroxyl groups and comprising hydroxyl groups, i.e. especially in an aqueous mixture or an aqueous binder system.

To the extent of the variants of the process according to the invention, in which the molding material mixture produced in step V1) as hardener component c) (at least) the component c2), one or more polyisocyanates, as crosslinking agent for hydroxyl groups of aliphatic polymers (only or also, preferably also, in addition to constituent c1)), an inventive method specified above, preferably an inventive method (ii) (preferably an inventive method described above or below as preferred) is preferred, the one or several aliphatic polymers each comprising hydroxyl-containing structural units of the formula I (component b)) and which provide or use one or more polyisocyanates as crosslinking agents for hydroxyl groups of the aliphatic polymer (s) (component c2)) as an aqueous mixture as first binder system comprising: b) one or more aliphatic polymers each comprising structural units of the formula I containing hydroxyl groups

-CH ₂ -CH (OH) - (I), and c2) one or more polyisocyanates (as defined above or below or defined as preferred) as crosslinking agents for hydroxyl groups of the aliphatic polymer or polymers.

Preferably, the aforementioned aqueous mixture to be used in the process according to the invention for producing the molding material mixture in step V31) comprises, as the first binder system (hereinafter also referred to as “first binder system”), one or more aliphatic polymers, each comprising hydroxyl group-containing structural units of the formula I in a total amount in the range from 5% by weight to 40% by weight, particularly preferably in the range from 7.5% by weight to 35% by weight and very particularly preferably in the range from 10% by weight to 30% by weight %, based on the total mass of the first binder system. The aforementioned first binder system to be used in the process according to the invention preferably comprises the one or more polyisocyanates (as defined above or below or defined as preferred), preferably the one or more aliphatic polyisocyanates in a total amount in the range from 1% by weight to 20% by weight. %, particularly preferably in the range from 2.5% by weight to 15% by weight and very particularly preferably in the range from 3% by weight to 10% by weight, based on the total mass of the first binder system. In a preferred variant of the method according to the invention specified above, the weight fractions of constituents b), c2) (in each case as defined above) and d) water in the aqueous mixture add up to 100% by weight, ie to the total mass of the aqueous mixture as the first binder system. Preferably, in the aqueous mixture as the first binder system, the aliphatic polymers used each contain hydroxyl-containing structural units of the formula I in an amount of> 90% by weight, particularly preferably> 95% by weight, in solution, based on the total mass of aliphatic polymers used .

In the variants of the process according to the invention specified above or below, in which the molding material mixture prepared in step V1) as hardener component c) (at least) the component c2), one or more polyisocyanates (as defined above or below or defined as preferred) as crosslinking agents for hydroxyl groups of the aliphatic polymer (s) (only or also, preferably also, in addition to component c1)), it is preferred if the components of the molding material mixture b) and c2) are brought into contact with one another only immediately before the molding material mixture is prepared are, preferably not earlier than one hour before the production of the molding material mixture. This prevents an undesirable premature start of a crosslinking reaction of the one or more polyisocyanates with hydroxyl groups of the one or more aliphatic polymers (e.g. in the absence of the basic molding material).

It has also been shown in our own experiments that a mixture of molding materials is obtained if components b), one or more aliphatic polymers, and c2) are particularly easy to process and shape, for example in shooting machines or molding boxes (such as core boxes) or more polyisocyanates (as defined above or below or defined as preferred), the molding material mixture in step V1) in the amounts or proportions given above.

It has also been shown in our own experiments that the preferred variant of the process according to the invention, in which the one or more aliphatic polymers (component b)) and the one or more polyisocyanates (component c2)) are used in the form of an aqueous mixture as the first binder system , leads to a particularly homogeneous mixing of the components b) and c2) with one another, so that, for example, the crosslinking of hydroxyl groups of the aliphatic polymer or polymers with isocyanate groups of the polyisocyanate crosslinking agent in the presence of the basic molding material (Step V33)) takes place particularly completely and thus the molded molding material mixture (or a resulting, non-hardened secondary product) is transferred particularly completely and homogeneously into a hardened molding or into a cross-linked, hardened molding. Within the scope of the preferred variants of the process according to the invention, in which the molding material mixture prepared in step V1) as hardener component c) includes both component c1), one or more biopolymers selected from the group of poly-D-glucosamines, and component c2) , one or more polyisocyanates, as crosslinking agents for hydroxyl groups of the aliphatic polymer (s), an above-mentioned inventive method, preferably an inventive method (ii) (preferably an above or below preferred method according to the invention) is preferred, the constituents b), c1) and c2) are provided or used as an aqueous mixture as a second binder system comprising: b) one or more aliphatic polymers, each comprising hydroxyl group-containing structural units of the formula I.

-CH ₂ -CH (OH) - (I), d) one or more biopolymers selected from the group of the poly-D-glucosamines and c2) one or more polyisocyanates (as defined above or below or defined as preferred), preferably one or more aliphatic polyisocyanates, as crosslinking agents for hydroxyl groups of the aliphatic polymer or polymers.

The aforementioned aqueous mixture to be used in the process according to the invention preferably comprises, as the second binder system (hereinafter also referred to as “second binder system”), the one or more polyisocyanates (as defined above or below or defined as preferred), preferably the one or more aliphatic polymers each comprising structural units of the formula I containing hydroxyl groups in a total amount in the range from 5% by weight to 30% by weight, particularly preferably in the range from 7.5% by weight to 25% by weight and very particularly preferably in the Range from 10 wt .-% to 20 wt .-%, based on the total mass of the aqueous second binder system.

Preferably, the aforementioned aqueous mixture to be used in the process according to the invention comprises, as a second binder system, the one or more biopolymers selected from the group of poly-D-glucosamines in a total amount in the range from 0.25% by weight to 5% by weight , particularly preferably in the range from 0.4% by weight to 3.5% by weight and very particularly preferably in the range from 0.5% by weight to 2.5% by weight, based on the total mass of the aqueous second binder system.

The aforementioned second binder system to be used in the process according to the invention preferably comprises the one or more polyisocyanates (as defined above or below or defined as preferred), preferably the one or more aliphatic polyisocyanates in a total amount in the range from 1% by weight to 15% by weight. %, particularly preferably in the range from 2% by weight to 10% by weight and very particularly preferably in the range from 2.5% by weight to 7.5% by weight, based on the total mass of the aqueous second binder system .

In a preferred variant of the method according to the invention specified above, the weight fractions of the components b), c1), c2) (in each case as defined above) and d) water in the aqueous mixture as a second binder system add up to 100% by weight, i.e. to the total mass of the aqueous mixture as a second binder system. Preferably, in the aqueous mixture as the second binder system, the aliphatic polymers used each contain structural units of the formula I comprising hydroxyl groups in an amount of> 90% by weight, particularly preferably> 95% by weight, in solution, based on the total mass of aliphatic polymers used .

It has been shown that the preferred variant of the method according to the invention, wherein the one or more aliphatic polymers (component b)), the one or more biopolymers selected from the group of poly-D-glucosamines (component c1)) and the one or several polyisocyanates (component c2)) is used in the form of a second binder system, leads to a particularly homogeneous mixing of its components with one another, so that in particular the crosslinking of hydroxyl groups of the aliphatic polymer or polymers with isocyanate groups of the crosslinking agent The shape of the raw material is particularly complete and the molded molding mixture is thus converted particularly completely and homogeneously into a hardened molding or into a crosslinked, hardened molding.

A method according to the invention specified above is also preferred, preferably a method (ii) according to the invention (preferably a method according to the invention designated above or below as preferred), wherein

- The relationship

- The total mass of aqueous mixture or aqueous mixtures used for producing the molding material mixture (in step V1)), preferably selected from the group consisting of the aqueous mixture comprising one or more aliphatic polymers, each comprising hydroxyl-containing structural units of the formula I, comprising the aqueous preparation one or more biopolymers selected from the group of poly-D-glucosamines, the aqueous mixture as the first binder system and the aqueous mixture as the second binder system; to

- Total mass of molding raw material used (in step V 1)); is in the range from 1: 100 to 50: 100, preferably in the range from 1.5: 100 to 40: 100, particularly preferably in the range from 2: 100 to 35: 100. The setting of the (number) ratio of the above The sum of the total mass of the aqueous mixture or aqueous mixtures used and the total mass of molding material used is preferably carried out in such a way that a moldable mixture which can be closed or tamped results in a molded part selected from the group consisting of mold, core and feeder. In this context, it has been shown that the ratio that is suitable in the individual case (with the concentrations of the aqueous mixtures used unchanged) depends, among other things, on the type of molding material used: the suitable numerical ratio given above is usually in the higher range (ie closer to the upper limit) of 50: 100 or 40: 100) in cases in which a mold base material with a lower bulk density (preferably as quartz sand) is used, while the suitable numerical ratio given above tends to be in the lower range (ie closer to the lower limit of 1: 100 or 1.5: 100) is in cases in which a mold base material with a higher bulk density (preferably quartz sand) is used.

Also preferred is a method according to the invention specified above, preferably a method according to the invention (ii) (preferably a method according to the invention designated above or below as preferred) (preferably a method according to the invention, the molding material mixture as hardener component c) comprising both component c1), one or more Biopolymers selected from the group of poly-D-glucosamines, as well as additionally component c2), one or more polyisocyanates), where

- the ratio of the sum

- The total mass of the aliphatic polymers used, each comprising hydroxyl-containing structural units of the formula I and

- The total mass of biopolymers used selected from the group of poly-D-glucosamines (if present or used) for

- Total mass of the preferably aliphatic polyisocyanates used as crosslinking agents (if present or used) is in the range from 1: 1 to 10: 1, preferably in the range from 1.5: 1 to 7.5: 1, particularly preferably in the range from 2: 1 to 5: 1. It has been shown that when carrying out the process according to the invention with the abovementioned biopolymers selected from the group of the poly-D-glucosamines (component c1)), the aliphatic polymers each comprising structural units of the formula I (component b)) and the as Crosslinking agents used, preferably aliphatic, polyisocyanates (component c2), in the amounts and ratios given above results in a green-solid molded part which is excellently suitable for further processing by the process according to the invention in the step of crosslinking hydroxyl groups of the aliphatic polymer or polymers with isocyanate groups of the crosslinking agent (step V33)), so that a green-stable molded part can be transferred particularly well (in step V32)) into a hardened molded part or (through step V32) and additionally step V33)) into a crosslinked, hardened molded part can.

Also preferred is a method according to the invention specified above, preferably a method (ii) according to the invention (preferably a method according to the invention designated above or below as preferred), the (at least one) mold base comprising:

- One or more particulate refractory solids, preferably selected from the group consisting of

Oxides, silicates and carbides, each comprising one or more elements from the group consisting of Si, Al, Zr, Ti, Mg, Fe and Ca,

Mixed oxides, mixed carbides and mixed nitrides, each comprising one or more elements from the group consisting of Si, Al, Zr, Ti, Mg, Fe and Ca, and graphite and / or

one or more particulate light fillers, preferably selected from the group consisting of: Core-shell particles, preferably having a glass core and a refractory shell, particularly preferably with a bulk density in the range of 470-500 g / L, preferably as described in document WO 2008/1 13765 A1; refractory composite particles, preferably as described in or produced according to document WO 2017/093371 A1;

Spheres, preferably spheres from fly ash, such as e.g. Spheres “Fillite 106” from Omya GmbH;

Perlite, preferably expanded perlite, such as expanded perlite with the names "Eurocell 140", "Eurocell 145", "Eurocell 150" or "Eurocell 300" from RS Rohstoff-Sourcing GmbH; closed-pore micro-balls made of expanded pearlite, preferably as described in document WO 2017/174826 A1;

Rice bowl ash, preferably as described in document WO 2013/0141 18 A2;

Expanded glass,

Hollow glass spheres, and ceramic hollow spheres, preferably hollow spherical corundum. The aforementioned one or more particulate refractory solids can be used individually or in combination with one another and thus form the basic molding material to be used in the process according to the invention. Likewise, the aforementioned one or more particulate light fillers can be used individually or in combination with one another and thus form the basic molding material to be used. Of course, the one or more particulate refractory solids can also be used in combination with the one or more particulate light fillers and so on form the basic molding material to be used. Depending on the intended use of the method according to the invention, ie depending on the hardened molded part to be produced, the person skilled in the art selects the appropriate mold base material. For example, only quartz sand can be selected as the basic molding material for producing a simple casting mold. Furthermore, a mixture of quartz sand with one or more particulate light fillers can be selected, for example, for the production of a feeder, or one or more particulate light fillers can also be selected for this purpose, preferably selected from the preferred group of light fillers defined above.

In addition to the preferred ingredients mentioned above, the mold base material to be used in the process according to the invention can also contain further, preferably particulate, constituents, preferably selected from the group consisting of elemental metals (for example aluminum), oxidizing agents and ignition agents. For example, in order to produce an exothermic feeder, the basic molding material to be used may contain aluminum, iron oxide, oxidizing agents known per se for this purpose and ignition means known per se for this purpose in addition to the above-mentioned constituents (selected from refractory solids and light fillers).

Also preferred is a method according to the invention specified above, preferably a method (i) according to the invention (preferably a method according to the invention designated above or below as preferred) for producing a metallic casting with the following additional step (preferably additionally carried out after performing step V32) and / or Step V33), particularly preferably additionally carried out after carrying out both steps V32) and V33)):

V4) contacting the hardened molded part, preferably as obtained after step V32) and preferably additionally step V33), with a cast metal for producing a metallic casting, the cast metal preferably solidifying in contact with the hardened molded part, preferably

- The casting metal is selected from the group consisting of aluminum, magnesium, tin, zinc and their alloys and / or - The temperature of the cast metal during casting is not higher than 900 ° C; so that a metallic casting results.

In the preferred method according to the invention for producing a metallic casting described above, the casting metal is at least partially and preferably completely liquid when the hardened molded part or the crosslinked, hardened molded part comes into contact. Any castable metal or castable metal alloy, in particular light metals and their alloys, for example aluminum, magnesium, tin and zinc, is suitable as the casting metal; as well as iron and steel.

It has been shown in our own investigations that when contacting the hardened molded part produced according to the invention, in particular when contacting the crosslinked, hardened molded part produced according to the invention, with the cast metal - regardless of the nature of the cast metal - at most small amounts of soot or smoke or Smoke is formed and hardly, or ideally no, gaseous emissions, which are potentially harmful to humans, occur, for example due to the decomposition of the crosslinked binder of the crosslinked, hardened molded part under the action of the heat of the liquid casting metal. This even applies to relatively low temperatures in the range from 600 ° C to 900 ° C, so that the aforementioned preferred process variant (i) is particularly suitable for the production of metallic castings, the cast metal being a light metal or a light metal alloy: it is Namely, it is known that at the relatively low temperatures prevailing in light metal casting (compared to the temperatures in iron or steel casting), conventional, currently frequently used, cold box binders are often only incompletely thermally decomposed, so that precisely in these cases - Both when casting metal and when unpacking the molds - there is a particularly strong formation of smoke, smoke or soot as well as a strong release of gaseous, aromatic-containing emissions, which are usually accompanied by unpleasant smells and are potentially harmful to people's health.

Such disadvantages exist when using hardened moldings produced by the process according to the invention or when carrying out the preferred process variant (i) according to the invention specified above, in particular the preferred process variants (i) described in this text, on the other hand to a much lesser extent or ideally not at all. Because of feeders or feeder caps by their position tion on the contact surface of casting molds with the ambient air poses a particularly strong emission hazard in the case of metal casting, the preferred process variant (i) according to the invention specified above is particularly effective if feeders or feeder caps are produced as hardened molded parts by the process according to the invention (process variant ( ii)) or are used (method variant (i)), in particular if these have been crosslinked by the method according to the invention (in step V33)).

The present invention further relates to a hardened molded part, preferably producible by a process according to the invention (ii) given above (preferably by a process according to the invention described above or below as preferred) selected from the group consisting of mold, core and feeder, for use in Casting of metallic castings, comprising the following constituents: a) at least one basic molding material, one or more aliphatic polymers, each comprising structural units of the formula I containing hydroxyl groups

-CH ₂ -CH (OH) - (I), and c) as hardener component, one or both constituents selected from the group consisting of: c1) one or more, preferably precipitated, biopolymers selected from the

Group of the poly-D-glucosamines, preferably comprising chitosan and c2) one or more, preferably aliphatic, particularly preferably water-dispersible aliphatic, polyisocyanates, preferably the hydroxyl groups of the aliphatic polymers used each comprising hydroxyl-containing structural units of the formula I (component b)) at least partially present than through networking Binder hardened, preferably crosslinked, hardened with isocyanate groups of the one or more polyisocyanates used.

With regard to preferred configurations of the hardened molded part according to the invention and possible combinations of one or more associated aspects with one another, the explanations given above for the method according to the invention apply accordingly, and vice versa.

Preferred as the above-mentioned hardened molded part according to the invention is a green-shaped molded part comprising, as hardener component c), component c1), one or more precipitated biopolymers selected from the group of poly-D-glucosamines, preferably comprising chitosan.

If the molded part according to the invention, which is green-stable, also comprises constituent c2), one or more, preferably aliphatic, particularly preferably water-dispersible aliphatic, polyisocyanates, these are one or more polyisocyanates and the structural units of the formula I each containing hydroxyl groups and comprising hydroxyl groups preferably not cross-linked (with each other) in the green stand-proof molded part.

Preferred as the above-mentioned hardened molded part according to the invention is also a (crosslinked) hardened molded part comprising, as hardener component c), component c2), one or more, preferably aliphatic, particularly preferably water-dispersible, aliphatic, polyisocyanates, the hydroxyl groups of the ones used aliphatic polymers each comprising hydroxyl-containing structural units of the formula I (component b)) are at least partially present as a crosslinked, hardened binder crosslinked by crosslinking with isocyanate groups of the one or more polyisocyanates used (component c2)). If a hardened (or crosslinked, hardened) molded part according to the invention comprises a crosslinked binder by crosslinking hydroxy groups of the aliphatic polymers used, each comprising structural units of the formula I (component b)) containing isocyanate groups of the one or more polyisocyanates used (component c2)) For the purposes of the present invention, it is assumed that in the molded part according to the invention the hydroxyl groups of the crosslinked or crosslinking aliphatic polymer after the crosslinking by the isocyanate groups of the one or more polyisocyanates used are (at least predominantly) not are more freely available, but (at least predominantly) are involved in the formation of urethane groups with the isocyanate groups.

The present invention also relates to a hardened molded part selected from the group consisting of casting mold, core and feeder, produced or producible by a process according to the invention specified above, preferably by a process (ii) according to the invention (or a preferred process according to the invention described in this text) ).

With regard to preferred configurations of the hardened molding produced or producible according to the invention and possible combinations of one or more associated aspects with one another, the explanations given above for the method according to the invention and for the hardened molding according to the invention apply accordingly, and vice versa.

An above-mentioned (crosslinked) hardened molded part according to the invention (or a corresponding preferred crosslinked, hardened molded part according to the invention described in this text or a crosslinked, hardened molded part which can be produced by the above-described method according to the invention) is preferred, the ratio

the total mass of the hardened binder present in the molded part to the total mass of the basic molding material present in the molded part in the range from 0.1: 100 to 10: 100, preferably in the range from 0.5: 100 to 7: 100 and particularly preferably in the range from 0 , 6: 100 to 6: 100.

The present invention also relates to a molding material mixture, preferably for the production of a hardened molded part (including a green-resistant molded part, if component c1) is present as hardener component and / or a crosslinked, hardened molded part, if component c2) is present as hardener component) from the group consisting of mold, core and feeder, for use in casting metallic castings, comprising the following components: a) at least one basic molding material, b) one or more aliphatic polymers each comprising structural units of the formula I containing hydroxyl groups

-CH ₂ -CH (OH) - (I), c) as hardener component, one or both components selected from the group consisting of: d) one or more biopolymers selected from the group of poly-D-glucosamines, preferably chitosan , and c2) one or more, preferably water-dispersible and / or aliphatic, polyisocyanates, as crosslinking agents for hydroxyl groups of the aliphatic polymer or polymers; and d) water. In a particularly preferred variant of the above-mentioned molding material mixture according to the invention, this comprises, as hardener component c), component c1), one or more biopolymers selected from the group of poly-D-glucosamines, preferably chitosan, and additionally component c2), one or more, preferably aliphatic, polyisocyanates, as crosslinking agents for hydroxyl groups of the aliphatic polymer (s).

In a preferred variant of the above-mentioned molding material mixture according to the invention, this comprises, as hardener component c), only component c1), one or more biopolymers selected from the group of poly-D-glucosamines, preferably chitosan, but not component c2), one or more, preferably water-dispersible and / or aliphatic, polyisocyanates, as crosslinking agents for hydroxyl groups of the aliphatic polymer or polymers. In another preferred variant of the above-mentioned molding material mixture according to the invention, this comprises, as hardener component c), only component c2), one or more aliphatic polyisocyanates (preferably one or more aliphatic polyisocyanates to be used in the present text as preferred according to the invention) as crosslinking agents for hydroxyl groups aliphatic polymers, but not component c1), one or more biopolymers selected from the group of poly-D-glucosamines, preferably chitosan.

With regard to preferred configurations of the molding material mixture according to the invention and possible combinations of one or more associated aspects with one another, the explanations given above for the method according to the invention, the hardened molded part according to the invention and the hardened molded part produced or producible according to the invention apply accordingly, and vice versa.

The above-mentioned molding material mixture according to the invention (or a molding material mixture according to the invention mentioned above, referred to as preferred in this text) is suitable for use in the method according to the invention specified above and is intended for this purpose.

The present invention also relates to the use of an aliphatic polymer which is crosslinked by one or more aliphatic polyisocyanates and comprises structural units of the formula I -CH ₂ -CH (OH) - (I), preferably a crosslinked polyvinyl alcohol, which contains hydroxyl groups and is selected as the binder of a hardened molding the group consisting of mold, core and feeder, for use in the casting of metal castings.

With regard to preferred refinements of the use according to the invention and possible combinations of one or more associated aspects with one another, the statements made above for the method according to the invention, the hardened molded part according to the invention, the hardened molded part produced or producible according to the invention and for the molding material mixture according to the invention apply accordingly, and vice versa. The present invention also relates to the use of biopolymers selected from the group of poly-D-glucosamines, preferably chitosan, as binders or binder components for producing a hardened molded part, preferably a green-shaped molded part, selected from the group consisting of a casting mold, Core and feeder, in the foundry industry.

With regard to preferred configurations of the use of biopolymers according to the invention and possible combinations of one or more associated aspects with one another, the same applies to the method according to the invention, the hardened molded part according to the invention, the hardened molded part produced or producible according to the invention, the molding material mixture according to the invention and the use according to the invention of one or more aliphatic polyisocyanates crosslinked aliphatic polymer in accordance with the explanations given above, and vice versa.

Examples:

The examples given below are intended to describe and explain the invention in more detail without restricting its scope.

Unless otherwise stated, the tests were carried out under laboratory conditions (normal pressure, temperature 20 ° C, humidity 50%).

Example 1: Preparation of molding mixtures

The constituents given in Table 1 below and described in more detail under Table 1 were used to produce mixtures of molding materials.

The molding material mixtures “F-Cold-Box” and “F-water glass” are comparative molding material mixtures not according to the invention or not to be used according to the invention. The molding material mixtures and “F-V6” and “F-E6 +” are molding material mixtures according to the invention or to be used according to the invention.

Table 1: Components of molding material mixtures

Quartz sand BO 42 (CAS No. 014808-60-7) from Bodensteiner Sandwerk GmbH & Co. KG was used as the basic molding material.

A 25% by weight solution of polyvinyl alcohol (> 93% polyvinyl alcohol) with a degree of hydrolysis of approx. 88 mol% and a dynamic was used as the aqueous PVAL mixture

Viscosity in the range from 3.5 to 4.5 mPa s (measured as a 4% by weight aqueous solution at 20 ° C. according to DIN 53015), methanol content: 3% by weight; CAS RN 25213-24-5 (Kuraray Europe GmbH).

The non-ionically hydrophilized polyisocyanate "Desmodur® DA-L" (Covestro AG) of the polyether urethane type (CAS RN 125252-47-3) was used as the aliphatic polyisocyanate.

A 2.5% by weight solution (based on the total mass of the solution) of chitosan 85/1000 (with a degree of deacetylation of 85 mol% and a dynamic viscosity of 1000 mPas It. Manufacturer information: Heppe Medical Chitosan GmbH) in a 1% by weight aqueous acetic acid solution (based on the total mass of the solution).

The cold box activator 6324 used was a polyisocyanate (activator 6324 from Huentnes-Albertus Chemische Werke GmbH) which is customary for the production of cold box binders (polyurethane resin based on benzyl ether). A phenolic resin (gas resin 7241 from Hüttenes-Albertus Chemische Werke GmbH), which is customary for the production of cold box binders (polyurethane resin based on benzyl ether), was used as the cold box gas resin 7241.

An aqueous solution of a standard water glass binder with a water glass content (sodium silicate content) in the range from 35% by weight to 50% by weight and a pH at 20 ° C. was used as the sodium water glass binder 48/50 from 1 1 to 12 (CAS RN 1344-09-8).

The molding material mixtures were produced as follows:

Molding material mixture F-Cold-Box: The components listed in Table 1 were mixed in an electric mixer (Bosch Profi 67) with stirring until a homogeneous molding material mixture was obtained. The cold box molding material mixture is a molding material mixture which is not produced by the process according to the invention or is not to be used in such a process, for comparison purposes.

F-water glass molding material mixture: The components listed in Table 1 were mixed in an electric mixer (Bosch Profi 67) with stirring until a homogeneous molding material mixture was obtained. The molding material mixture F-water glass is a molding material mixture which is not produced by the process according to the invention or which is not to be used in such a process, for comparison purposes.

Molding material mixture F-V6: The components "aqueous PVAL mixture" and "aqueous preparation of chitosan" listed in Table 1 were mixed together in the amounts specified in Table 1 in a beaker to form a binder premix. The quartz sand was then placed in an electric mixer (Bosch Profi 67) and the binder premix was then added with stirring and mixed with the quartz sand. The stirring was continued until a homogeneous mixture of molding materials was obtained. The molding material mixture F-V6 is a molding material mixture produced by the process according to the invention or to be used in such a process.

Molding material mixture F-E6 +: the components “aqueous PVAL mixture” and “aqueous preparation of chitosan” listed in Table 1 were mixed together in the amounts specified in Table 1 in a beaker to form a binder premix. Shortly before the production of the molding material mixture F-E6 + became the resulting one Binder premix added the amount of aliphatic polyisocyanate shown in Table 1 and combined with the binder premix by mixing together (agitator motor with paddle stirrer) to form a “second binder system” (in the sense of the present invention). The quartz sand was then placed in an electric mixer (Bosch Profi 67) and the resulting second binder system was then added with stirring and combined with the quartz sand by mixing. The stirring was continued until a homogeneous mixture of molding materials was obtained. The molding material mixture F-E6 + is a molding material mixture produced by the process according to the invention or to be used in such a process. Example 2: Production of standard Bieqerieqeln as model molded parts

From the molding material mixtures F-Cold-Box, F-water glass, F-V6 and F-E6 + specified in Example 1, standard bending bars (representative of a hardened molded part for use in casting metallic castings) were used for test purposes in a manner known to the person skilled in the art Rams manufactured (dimensions: 172 x 23 x 23 mm), in accordance with or analogous to the regulation in leaflet P73 (February 1996 edition) of the Association of German Foundry Professionals (hereinafter referred to as "VDG leaflet P73"), No. 4.1.

The bending bars described above were hardened as indicated below (the processes for hardening the molding material mixtures “F-Cold-Box” and “F-water glass” as indicated below correspond to processes known from the prior art):

Bending bar B-Cold-Box: The molding material mixture F-Cold-Box (see Example 1) was shaped in a bending rod ram as described above by ramming. The molded molding material mixture was then subjected to the cold box process by passing gaseous N, N-dimethylpropylamine (approx. 1 ml liquid, 15 s) (under the process conditions) in accordance with the instructions in VDG leaflet P73, No. 4.3, process A , hardened.

Bending bar B-water glass: The molding material mixture F-water glass was formed by ramming in a bending rod ram as described above. Gaseous CO2 was then passed through the molded molding material mixture (in the bending rod ram sleeve). The green bar, which was stable after C0 ₂ fumigation, was removed from the mold (demoulded) and dried in a drying oven for 20 min at 210 ° C and removal of water hardened by ventilating the drying oven (standard bending bar, here: bending bar B water glass).

Bending bars B-V6 and B-E6 +: the molding material mixtures F-V6 and F-E6 + (production see Example 1) were each formed by ramming in a bending rod ram as described above. Subsequently, gaseous N, N-dimethylpropylamine (corresponding to approx. 1 ml liquid, 15 s) was passed through the molded molding material mixtures (under the process conditions) (gassing in the bending rod ram bushing), whereby in each case a green-stable standard bending bar (ie model, hardened - here: green stable - molded part) resulted. These green-stable standard bending bars were then removed from the ram and each in the drying oven for 20 min at 210 ° C and removing water by venting the drying oven to the hardened molded part (standard bending bar, here: bending bar B-V6) or hardened molded part with crosslinking step (bending bar B-E6 +) processed.

Example 3: Determination of the final strengths of standard bending jars The final strengths of the standard bending bars produced in Example 2 above were tested: the final strength of the standard bending bar B-Cold-Box was checked 24 hours after its manufacture. The final strengths of the standard bending bars B-water glass, B-V6 and B-E6 + were tested for this 30 minutes after their manufacture (drying). All standard bending bars were stored under laboratory conditions. The final strengths were determined in triplicate, as described in VDG Leaflet P73, No. 5.2, with a Georg Fischer type PFG strength tester with low-pressure manometer (with motor drive).

The bending strengths (final strengths) of the standard bending bars given below in Table 2 were determined in this way: Table 2: final strengths of standard bending bars

Aus den in Tabelle 2 angegebenen Werten kann man ersehen, dass das nach dem erfindungsgemäßen Verfahren hergestellte gehärtete Formteile (Standard-Biegeriegel) B-V6 und B-E6+ zwar geringere Endfestigkeiten aufweisen als herkömmliche Cold-Box- oder Wasserglas-gebundene Formteile, dass aber die Endfestigkeiten der nach dem erfin- dungsgemäßen Verfahren hergestellten gehärteten Formteile in der Praxis vollständig ausreichend sind. Der Standard-Biegeriegel B-E6+ (mit Vernetzungsschritt hergestellt) wies einen höheren (dem entsprechenden Wert für einen Cold-Box-gebundenen Biegeriegel nahekommenden) Wert für die Endfestigkeit auf, als der Standard-Biegeriegel B-V6 (ohne Vernetzungsschritt hergestellt). Beispiel 4: Bestimmung der Festigkeit von Standard-Bieqerieqeln nach Auslagerung

It can be seen from the values given in Table 2 that the hardened molded parts (standard bending bars) B-V6 and B-E6 + produced by the process according to the invention have lower final strengths than conventional cold box or water glass-bonded molded parts, but that the final strengths of the hardened molded parts produced by the process according to the invention are completely sufficient in practice. The standard bending bar B-E6 + (produced with the cross-linking step) had a higher (near the corresponding value for a cold box-bound bending bar) for the ultimate strength than the standard bending bar B-V6 (produced without the cross-linking step). Example 4: Determination of the strength of standard Bieqerieqeln after aging

Standard bending bars B-water glass and B-E6 + produced as in Example 2 above were subjected to a storage test starting 24 h after their production (corresponds to aging time "0"). For this purpose, corresponding bending bars were stored for 60 h in a climatic cabinet at 40 ° C. and 90% relative atmospheric humidity and, in the time intervals specified in Table 3, as indicated in Example 3, on their (remaining)

Flexural strength tested. The respectively measured values of these bending strengths are given in Table 3 below:

Table 3: Flexural strength after aging in a climatic cabinet for 60 h

It can be seen from the values given in Table 3 that the hardened molded part (standard bending bar) B-E6 + produced by the process according to the invention shows a drop in strength after 8 hours under the storage conditions. After that, its strength remains almost constant over the rest of the storage period and is sufficient for practical purposes. In contrast, a significant decrease in strength after 24 hours of storage can be observed with the water-glass-bound bending bar B-water glass, which continues until the end of the storage period until it becomes unusable. The hardened molded part produced by the process according to the invention (standard bending bar, produced using the crosslinking step) B-E6 + is therefore significantly better suited for storage even under difficult climatic conditions (elevated temperature and air humidity) than a conventional, water glass-bound molded part.

Example 5: Determination of the Water Resistance of Standard Bieqerieqeln Standard bending bars produced as in Example 2 above were placed on shelves so that only their ends rested (contact area approx. 1/10 of the total area of the underside of the standard bending bars). The shelves with the standard bending bars placed on them were placed in a water-filled container so that the undersides of the standard bending bars rested completely on the water surface and could absorb water through the capillary forces. The water resistance of the standard bending bars was then assessed visually over a period given in Table 4 below.

The results of this experiment are shown in Table 4 below. Table 4: Water resistance of standard bending bars

It can be seen from the observations given in Table 4 that the standard bending bar bound with cold box binder was still completely water-resistant even after the longest exposure time to water, as shown in Table 4. The hardened bending bar B-V6 produced by the method according to the invention (produced without a crosslinking step) took up water after a short time and broke after some time. The bending bar B-E6 + produced according to the invention had a higher water resistance than the hardened (not cross-linked) bending bar B-V6. Example 6: Behavior of standard bending bars when casting iron

Standard bending bars B-Cold-Box (comparison), B-V6 (produced according to the method according to the invention) and B-E6 + (manufactured according to the method according to the invention) produced in Example 2 above were mixed with a conventional alcohol size (Koalid 4087 from Hüttenes- Albertus GmbH) finished in a manner known per se (conditions: run-down time 17.3 s; immersion time 7 s; drying 1 10 ° C for 40 min; wall thickness 325 pm when wet).

The standard bending bars finished with the alcohol size were then converted into a size with a conventional size containing zircon (Zirkofluid 1219 from Hüttenes-Albertus GmbH) undiluted finished furan resin mold (dimensions 280 x 200 x 130 mm) and cast in this form with iron lying down (casting temperature approx. 1440 ° C; approx. 3.09% by weight carbon content, approx. 1.89% by weight) .-% silicon content, based in each case on the total mass of the cast iron), so that the standard bending bars were completely enclosed by the iron casting and were subjected to a maximum load during casting in relation to the bearing load (due to the iron as casting metal).

After the casting process, the remains of the standard bending bars were removed by turning the iron casting (so that the remains of the standard bending bars could fall out of the downward openings of the cavities of the iron casting created by the standard bending bars) and the unpacking behavior (gutting behavior) of the standard bending bars was assessed visually. The following observations were made:

The remains of the standard B-Cold-Box bending bar (comparison) could hardly be removed from the iron casting in the manner described above; they remained almost completely in the iron casting.

The remains of the standard bending bars B-V6 (produced by the process according to the invention, without crosslinking step) and B-E6 + (produced by the process according to the invention, with crosslinking step) were very good and practically completely from the iron casting in the manner described above remove. There were hardly any visible remains in the iron casting.

From the aforementioned observations it can be seen that hardened molded parts produced by the process according to the invention (here: standard bending bars B-V6 or B-E6 +, representative of the core, feeder or mold) show very good removability and demoldability and are clearly superior to the comparison molded part (B-Cold Box) in this regard.

Example 7: Production of standard test specimens (standard bending bars and standard

Test cylinder) from insulating feed mass as a molding material mixture

The components listed in Table 5 below were used to produce molding material mixtures for insulating feeders. The molding material mixtures were prepared analogously to that given in Example 1 above. Bending bars were then formed from the molding material mixtures obtained and cured to standard bending bars in a manner analogous to that in Example 2 above. Furthermore, standard test cylinders (height: 50 mm, diameter: 50 mm) according to the VDG standard P38 were produced from the molding compounds obtained by ramming and hardened analogously as in Example 2 above, as hardened moldings (30 min at 210 ° C. in a convection drying oven for standard bending bars and standard test cylinders with molding material mixture F-E6 + (2)). In the case of the molding material mixture F-E6 + (2), the standard bending bars or standard test cylinders produced as described above correspond to hardened molded parts (with crosslinking step) in the sense of the invention. The final strengths of the standard bending bars “B-Cold-Box” (comparison) and the standard bending bars B-E6 + (2) (produced according to the invention) were then determined, analogously to that given in Example 3 above. The results of all corresponding measurements are given in Table 5 below (mean values from 3 measurements in each case). Table 5 also shows the respectively determined values of the gas permeability of the standard bending bars and standard test cylinders as well as their weight. The gas permeability is a test value that provides information about the structure compression. In the case of the feeder in particular, this is a characteristic value that can provide information about the sufficient removal of casting gases during the casting. Table 5: Components of molding material mixtures for insulating feeders

The ingredients listed in Table 5 "aqueous PVAL mixture", "aliphatic polyisocyanate", "aqueous preparation of chitosan", "cold box activator 6324" and "cold box gas resin 7241" correspond to the ingredients given in Example 1. From the results given in Table 5 above, it can be seen that an insulating feed mass produced by the process according to the invention had properties comparable to those of a feed mass produced by the cold box process known from the prior art.

EXAMPLE 8 Casting of Shaped Parts with Aluminum The insulating feed mass with molding material mixture “F-Cold-Box (2)” produced in Example 7 above was used in a manner known to the person skilled in the art (gassing with catalyst N, N-dimethylpropylamine) by firing in a core shooter Insulating feeders (closed at the bottom with a bottom). From the insulating feed mass with molding material mixture “F-E6 + (2)” produced according to the invention in Example 7 above, insulating feeders were shot in the same shape (as with the feed mass “F-Cold-Box (2)”) on the core shooter. The curing was carried out for 30 min at 210 ° C. with dehydration in a drying cabinet (circulating air). Insulating feeders produced in the above-mentioned manner from the two molding material mixtures used were placed in a sand mold bonded with a cold box and cast in each case with aluminum to test their behavior under metal casting conditions. Further insulating feeders likewise produced in this way were placed in loose molding sand and cast in each case with iron instead of aluminum. The following observations were made:

When casting with aluminum of the insulating feeder produced with the comparison molding material mixture F-Cold-Box (2) (not according to the method according to the invention), strong smoke formation was observed, which continued even after the cast feeder was removed from the sand mold. When casting with aluminum the insulating feeders produced with the molding material mixture F-E6 + (2) (according to the method according to the invention), no smoke formation was found. After the casting, the insulating feeder produced according to the invention showed a significantly better unpacking behavior than the insulating feeder produced with the comparison molding material mixture F-Cold-Box (2), i.e. the insulating feeder produced according to the invention was much easier to separate from the aluminum. The resulting aluminum castings showed a significantly cleaner surface (i.e. no condensate deposits) than the aluminum castings, which had been produced with the insulating feeder produced with the comparative molding material mixture F-Cold-Box (2).

Example 9: Sample Casting of Iron Cubes The molding material mixtures given below in Table 6 were each formed into (insulating) feeders in a core shooter in a manner known to the person skilled in the art.

In the case of the feeder mixture “F-Cold-Box (3)”, curing was carried out in a manner known to the person skilled in the art by gassing with the catalyst N, N-dimethylpropylamine. In the case of the feeder mixture "F-water glass (2)" the curing took place for 25 min at 210 ° C in a drying cabinet (circulating air). In the case of the feed mass "F-E6 + (3)" the hardening took place to cross-linked, hardened molded part by heating and removing water for 30 min at 210 ° C in a drying cabinet (circulating air). This resulted in the feeders “Speiser-Coldbox” and “Speiser-Wasserglas” which were not produced according to the invention and the feeder produced according to the invention “Speiser-B-E6 +”. Table 6: Compositions of molding material mixtures for feeders

The constituents indicated in Table 6 each correspond to the constituents indicated in Example 1 or their meanings. The above-mentioned feeders were each checked for their usability, in particular the quality of their feed effect, by use in the test casting of an iron cube (model for a metallic casting). For this purpose, the feeders of the same size (ie the same module in each case) were used for the trial casting of cubes of the module (ie with a volume to surface ratio of) 1.68 cm using iron (GGG40) at a casting temperature of 1400 ° C. For the quality assessment, the specialist in the field of foundry technology often uses cubes that have a significantly higher module than the feeders, in order to be able to obtain the best possible information on solidification from the test. The quality of the feeding effect is recorded via the depth of the blow hole reaching into the cube, whereby blow holes reaching deeper into the cube (the metal casting) mean a poorer feeding effect.

After the casting and cooling to room temperature, the sample cubes produced as above were sawn (halved) in the middle in order to expose their cross section and to assess the quality of the casting and the quality of the feed effect of the feeders used in each case. The cross sections of the test cubes obtained by sawing with the visible residual feeder made of iron placed on top were visually assessed, with the results given below:

When using a cold box-bound feeder not produced according to the invention, a clear void formation took place under the test conditions, which reached right into the metallic casting.

When using a water glass-bound feeder not produced according to the invention, a pronounced void formation took place under the test conditions, which reached far into the metal casting. The poor quality of the feed effect of the water glass-bound feeder under the test conditions is presumably due to the comparatively high thermal energy absorption of the water glass binder (known as its unfavorable "quenching behavior") and the resulting relatively early solidification of the casting metal.

In contrast, when using the feeder “Speiser-B-E6 +” produced according to the invention, there were no voids in the metallic casting, but essentially only at the upper end of the residual metal feeder. It can therefore be concluded from the observations given above that a feeder produced according to the invention has a significantly improved feeding capacity than the conventional cold box or water glass-bound feeders used for comparison. Example 10: Preparation of aqueous binder systems

The ingredients listed in Table 7 below were used to prepare aqueous binder systems.

Table 7: Components of aqueous binder systems

Die in Tabelle 7 angegebenen Bestandteile„wässrige PVAL-Mischung“,„aliphatisches Po- lyisocyanat“ und„wässrige Zubereitung von Chitosan“ entsprechen den in Beispiel 1 angegebenen Bestandteilen.

The constituents given in table 7 “aqueous PVAL mixture”, “aliphatic polyisocyanate” and “aqueous preparation of chitosan” correspond to the constituents specified in example 1.

The aqueous binder systems WB-V6 and WB-E6 + are aqueous binder systems to be used according to the invention. The aqueous binder system WB-E6 + corresponds to an aqueous mixture described above as the second binder system.

Claims

Claims: 1. Process i) for producing a metallic casting and / or ii) for producing a hardened molded part selected from the group consisting of casting mold, core and feeder, for use in casting metallic castings, with the following steps: V1) Preparation of a molding material mixture comprising the following constituents: a) at least one molding raw material, b) one or more aliphatic polymers each comprising structural units of the formula I containing hydroxyl groups -CH ₂ -CH (OH) - (I), c) as hardener component, one or both components selected from the group consisting of: c1) one or more biopolymers selected from the group of poly-D-glucosamines

c2) one or more polyisocyanates, as crosslinking agents for hydroxyl groups of the aliphatic polymer (s); and d) water; V 2) shaping the molding material mixture, and then V3) hardening the shaped molding material mixture or a resulting, non-hardened secondary product in one or more steps, so that a hardened molded part results. 2. The method according to claim 1, wherein the molding material mixture in step V1) is produced by intensive mixing of components a) to d) with one another. 3. The method according to any one of the preceding claims, wherein - The molding material mixture as hardener component c) comprises component c1), one or more biopolymers selected from the group of poly-D-glucosamines, and / or - Curing in step V3) V31) the precipitation of at least portions of the one or more biopolymers, preferably by increasing the pH of the aqueous portions of the molded molding material mixture, particularly preferably by contacting, preferably gassing, with an alkaline gaseous compound, very particularly preferably by gassing with a gaseous amine, so that a green component is obtained; and / or V32) the treatment of the shaped molding material mixture and / or the resulting, not hardened secondary product and / or the molded part which is stable on green, - by heating the molded molding material mixture and / or the resulting, non-hardened secondary product and / or of the molded part which is stable on green, preferably to a temperature in the range from 100 ° C. to 300 ° C., particularly preferably in the range from 150 ° C. to 250 ° C. and very particularly preferably in the range from 180 ° C. to 230 ° C., and / or - By removing water from the molded molding material mixture and / or from the resulting, non-hardened secondary product and / or from the green-proof molded part. 4. The method according to any one of the preceding claims, preferably according to claim 3, wherein - The molding material mixture as hardener component c) comprises component c2), one or more polyisocyanates, preferably aliphatic polyisocyanates, and / or - Curing in step V3) V32) the treatment of the shaped molding material mixture and / or the resulting product and / or the green-stable molded part, preferably - by heating the molded molding material mixture and / or the resulting product and / or the green-stable molded part, preferably to a temperature in the range of 100 ° C to 300 ° C, particularly preferably in the range from 150 ° C to 250 ° C and very particularly preferably in the range from 180 ° C to 230 ° C, and or - By removing water from the molded molding material mixture and / or from the resulting, not hardened secondary product and / or from the green-stable molded part, and preferably V33) the crosslinking of hydroxy groups of the aliphatic polymer (s) of the formula I with isocyanate groups of the polyisocyanates in the molded molding material mixture and / or in the resulting product and / or in the green-resistant molded part, so that a crosslinked molded part is used as the hardened molded part results. 5. The method according to any one of the preceding claims, wherein the aliphatic polymers used each comprising hydroxyl-containing structural units of the formula I can be prepared by at least partial saponification of polyvinyl acetate; and or - are selected from the group consisting of polyvinyl alcohols, polyvinyl acetates and their mixtures and / or -> 75% by weight, preferably> 90% by weight, particularly preferably> 98% by weight, of the total mass of the molding material mixture, in addition to the one or more biopolymers used as component c1), selected from the group of poly- D-glucosamines, total organic polymers comprising hydroxyl groups, and / or - comprise one or more polyvinyl alcohols, the entirety of the polyvinyl alcohols used preferably - Has a degree of hydrolysis of> 50 mol%, preferably determined according to the method as specified in document DE 10 2007 026 166 A1, paragraphs [0029] to [0034], and particularly preferably has a degree of hydrolysis in the range from 70 mol% to 100 mol%, very particularly preferably in the range from 80 mol% to 100 mol%, preferably determined according to the method according to DIN EN ISO 15023-02 2017-02 draft, Appendix D, and / or has a dynamic viscosity in the range from 0.1 to 30 mPas, preferably in the range from 1.0 to 15 mPas, particularly preferably in the range from 2.0 to 10 mPas, each determined at a 4% -igen (w / w) aqueous solution of the totality of the polyvinyl alcohols used at 20 ° C. according to DIN 53015: 2001-02; and or -> 75% by weight, preferably> 90% by weight, particularly preferably> 98% by weight, of the total mass of the aliphatic polymers used overall in the molding material mixture in each case comprising structural units of the formula I containing hydroxyl groups. 6. The method according to any one of the preceding claims, wherein - The one or one or more of the several biopolymers selected from the group of poly-D-glucosamines comprise chitosan, the chitosan preferably has a degree of deacetylation of> 70 mol%, preferably of> 75 mol% and particularly preferably of> 80 mol%, determined by means of 1H-NMR spectroscopy, and / or - a dynamic viscosity of> 500 mPa · s, preferably of> 600 mPa · s, particularly preferably of> 700 mPa · s, each determined using a 1% (w / w) solution of the chitosan in 1% (w / w) acetic acid at 20 ° C. DIN 53015: 2001-02, and / or - the ratio of the sum - The total mass of the aliphatic polymers used each comprising hydroxyl-containing structural units of the formula I and the total mass of biopolymers used selected from the Group of poly-D-glucosamines, for - Total mass of the molding material used, is in the range from 0.2: 100 to 13: 100, preferably in the range from 0.3: 100 to 10: 100, particularly preferably in the range from 0.5: 100 to 9: 100. 7. The method according to any one of the preceding claims, wherein the one or more polyisocyanates comprise one or more water-dispersible polyisocyanates. 8. The method according to any one of the preceding claims, wherein the one or more Polyisocyanates include aliphatic polyisocyanates, preferably - The one or one or more or all of the several aliphatic polyisocyanates are non-ionically or ionically hydrophilized, and / or - The one or one or more or all of the several aliphatic polyisocyanates comprises or comprise a polyether group or a sulfonate group, and / or - The one or one or more or all of the several aliphatic polyisocyanates comprises or comprise a polyether group and also a urethane and / or an allophanate group, and / or - The one or one or more or all of the several aliphatic polyisocyanates comprises or comprise one or more 2,4,6-trioxotriazine groups and preferably comprises or comprises a polyether group or a sulfonate group, preferably a polyether group, and / or - the one or one or more or all of the several aliphatic polyisocyanates comprise one or more 2,4,6-trioxotriazine groups and a polyether group and also a urethane and / or an allophanate group, preferably a urethane group, comprises or comprise, and / or the one or more aliphatic polyisocyanates used> 50% by weight, preferably> 75% by weight, particularly preferably> 90% by weight and very particularly preferably> 98% by weight, of the one or all used in the molding material mixture make up several polyisocyanates. 9. The method according to any one of the preceding claims, wherein - the ratio of the sum - The total mass of the aliphatic polymers used in each case comprising structural units of the formula I and hydroxy groups - The total mass of biopolymers used selected from the group of poly-D-glucosamines, - The total mass of the preferably aliphatic polyisocyanates used as crosslinking agents is in the range from 1: 1 to 10: 1, preferably in the range from 1.5: 1 to 7.5: 1 particularly preferably in the range from 2: 1 to 5: 1. 10. The method according to any one of the preceding claims, wherein the mold base comprises: - One or more particulate refractory solids selected from the group consisting of Oxides, silicates and carbides, each comprising one or more elements from the group consisting of Si, Al, Zr, Ti, Mg, Fe and Ca, Mixed oxides, mixed carbides and mixed nitrides, each comprising one or more elements from the group consisting of Si, Al, Zr, Ti, Mg, Fe and Ca, and - graphite and / or one or more particulate light fillers, preferably selected from the group consisting of: Core-shell particles, preferably having a glass core and a refractory shell, particularly preferably with a bulk density in the range of 470-500 g / L; - refractory composite particles; - Spheres; Pearlite, preferably expanded pearlite; - closed-pore micro-balls made of expanded pearlite; Rice bowl ash; Expanded glass, Hollow glass spheres, and ceramic hollow spheres, preferably hollow corundum. 1 1. Method i) for producing a metallic casting according to one of the preceding claims, preferably according to one of claims 3 to 10, with the following additional step: V4) contacting the hardened molded part, preferably as obtained after Step V32) and preferably additionally step V33), with a casting metal for producing a metallic casting, the casting metal preferably solidifying in contact with the hardened molded part, preferably - the casting metal being selected from the group consisting of aluminum, magnesium, tin, zinc and their alloys and / or - The temperature of the cast metal during casting is not higher than 900 ° C; so that a metallic casting results. 12. Hardened molded part, preferably producible by a process according to one of claims 1 to 1 1, selected from the group consisting of mold, core and feeder, for use in casting metallic castings, comprising a) at least one base material, b) one or several aliphatic polymers, each comprising hydroxyl-containing structural units of the formula I. -CH ₂ -CH (OH) - (I), and c) as hardener component, one or both constituents selected from the group consisting of: c1) one or more, preferably precipitated, biopolymers selected from the group of poly-D-glucosamines and c2) one or more, preferably aliphatic, polyisocyanates, preferably the hydroxyl groups of the aliphatic polymers used, each comprising structural units of the formula I containing hydroxyl groups, are at least partially present as a hardened, preferably crosslinked, hardened binder by crosslinking with isocyanate groups of the one or more polyisocyanates used. 13. Green-stable molded part according to claim 12, comprising as the hardener component c) the component c1), one or more precipitated biopolymers selected from the group of poly-D-glucosamines, preferably comprising chitosan. 14. Hardened molded part according to claim 12 or 13, comprising as the hardener component c) the component c2), one or more, preferably aliphatic, polyisocyanates, the hydroxyl groups of the aliphatic polymers used each comprising at least partially structural units of the formula I containing hydroxyl groups as by crosslinking with isocyanate groups of the one or more polyisocyanates used, hardened binder. 15. A molding material mixture comprising the following constituents: a) at least one basic molding material, b) one or more aliphatic polymers each comprising structural units of the formula I containing hydroxyl groups -CH ₂ -CH (OH) - (I), c) as hardener component, one or both components selected from the group consisting of: - One or more biopolymers selected from the group of poly-D-glucosamines and - One or more, preferably water-dispersible and / or aliphatic, polyisocyanates, as crosslinking agents for hydroxyl groups of the aliphatic polymer or polymers; and d) water. 16. Use of an aliphatic polymer crosslinked by one or more aliphatic polyisocyanates comprising structural units of the formula I containing hydroxyl groups -CH ₂ -CH (OH) - (I), preferably a polyvinyl alcohol crosslinked in this way, as a binder of a molded part selected from the group consisting of mold, core and feeder, for use in the casting of metallic castings. 17. Use of biopolymers selected from the group of poly-D-glucosamines, preferably chitosan, as a binder or binder component for the production of a hardened molded part, preferably a green-resistant molded part, selected from the group consisting of mold, core and feeder, in the foundry industry.