EP1417060B1 - Casting mould and method for the production thereof - Google Patents

Abstract

Water-dispersible casting mold, especially foundry core, for producing castings,contains a water-insoluble particulate material (I), especially molding sand, and a binder comprising condensed phosphate(s) (II) as first binder component, and polyamine(s) (III) as second binder component. An Independent claim is also included for production of such a mold by mixing (I), (II) and (III) with addition of water, molding and removing (part of) the added free water.

Description

The invention relates to a water-dispersible casting mold, in particular casting core, for the production of castings, the a water-insoluble, particulate material, in particular Foundry sand, a binder, which acts as a first binder component has at least one condensing phosphate. The invention further relates to a process for the preparation such a mold by a water-insoluble, Particulate material, in particular molding sand, with a binder, which as a first binder component at least having a condensed phosphate, with addition mixed by water, the mixture is shaped and at least one Part of the added free water is removed.

Foundry cores of the aforementioned composition are known. They are usually in core boxes using core shooters manufactured for mass production. The core boxes are provided with corresponding mold cavities, in which Introductory openings lead, via the so-called Shooting head a water-insoluble, provided with a binder, particulate material using compressed air is injected into the mold cavities. At the particulate Material is generally molding sand, such as silica, zircon, chromite sands or the like, which are solidifiable by the binder. For the production of cores with complex geometry, the molding sand should be a have good flowability.

As binders for the molding sand were conventionally liquid Synthetic resins and additional additives used. To the Disadvantages of synthetic resin binders - formation harmful to health Vapors during production, partial burning the binder when pouring, elaborate coring, disposal of the Kernaltsändes - to avoid, was already the use of at least some water-soluble proposed inorganic binders.

Thus, DE 195 49 469 A1 describes a casting core on the Base of solidified by means of a water-soluble binder Foundry sand, wherein as a binder phosphoric acid or condensed Phosphates, such as sodium polyphosphate and sodium hexametaphosphate, are provided.

WO 92/06808 Al, a casting core can be removed, which for Solidification of the molding sand a binder of a polyphosphate chains having water-soluble phosphate glass or from a water-soluble borate glass. For the production the foundry core is the molding sand with the binder under Adding water mixed, the mixture in the core box shot in and the excess water by heating expelled from the mold.

The known casting cores are water-dispersible after casting, i.e. they dissolve after immersion in water again, which eliminates the time-consuming coring. Another advantage of casting cores of this type is that both in the manufacture of the casting cores and the casting of the Castings as well as the coring of the castings no polluting Release substances. The binders used also have an inorganic chemistry, so that a burning of the binder during the casting reliably is avoided.

However, it has been shown that binder of the aforementioned Kind the casting core one for many applications only inadequate Give flexural strength. Consequently, the Foundry core during removal or storage after Shapes, when inserted into the mold or during the casting process deform or even break, leaving the obtained Castings can be faulty and as scrap parts attack. In addition, foundry cores of this type often insufficient abrasion resistance, resulting in the Drain off Sand grains on the surface of the casting core and a rough surface and / or sand contamination lead the casting. When using a binder comes on the basis of pure condensed phosphates added that the truss one for alloys with relative high melting point only insufficient temperature resistance so that the production of castings from such alloys is not possible. The occurrence the disadvantages mentioned can in particular by Variation of process parameters in the production of Gießkerns, such as the composition of the casting core, the Drying temperature, the residual water content, etc., not effective be countered.

The invention is based on the object of a casting mold, in particular a casting core, with a first binder component increased on the basis of condensed phosphates To give bending and abrasion resistance and temperature resistance to increase, but acceptable Cycle times in the core production to receive and none or release only small quantities of environmentally harmful substances. It is also concerned with the production of such a mold directed.

According to the invention this object is in a mold he mentioned type in that the binder as a second binder component comprises at least one polyamine.

Surprisingly, it has been found that both the bending and the abrasion resistance of a casting mold or a casting core of a water-insoluble, particulate material and a binder based on condensed phosphates can be significantly increased even by the addition of only small amounts of polyamines, without the water dispersibility affect the cast casting core. In this way, bending strengths of more than 150 N / cm ^{2 can be} achieved, reliably avoiding a failure of the casting core and resulting defective castings. At the same time, the abrasion resistance of the casting mold or of the casting core is improved in such a way that impairments of the casting by sand particles are virtually ruled out.

It is believed that the polar amino groups of the inventive second binder component based on polyamines with the polar phosphate groups of the first binder component based on condensed phosphates in Interaction and their binding properties thereby improve. With "polyamines" are in this context saturated or unsaturated, open-chain or cyclic organic compounds with multiple primary, secondary and / or tertiary amino groups, especially in liquid Form, meant. As water-insoluble, particulate materials in particular any known form sands, e.g. Silica, zirconium, chromite sands or the like, or Other temperature-resistant materials, such as aluminum oxide, Aluminum silicate, quartz glass etc. in fine particulate Form, into consideration. Of course, other can also Be provided binder components.

While in principle also low molecular weight polyamines, such as ethylene, propylene, butylenediamines, etc. and their condensation products, may be provided as the second binder component, a preferred embodiment provides that the polyamine is selected from the group of polymeric polyamines. Of these, in particular the polyethyleneimines, ie branched polymers having primary, secondary and tertiary amino groups, polyvinylamines (vinylamine polymers) and / or copolymers thereof have proven to be particularly advantageous. Thus, for example, the flexural strength of a foundry core of a foundry sand and a binder based on sodium polyphosphate can be almost doubled by the addition of 0.1% by mass of polyvinylamine, based on the molding sand. The polymeric polyamines can be provided in particular with a molecular weight between about 400 g / mol and about 10 ⁷ g / mol. The chemical formulas for polyvinylamine (I) and polyethyleneimine (II) are exemplified below:

In a preferred embodiment, it is provided that the polyamine has a nitrogen content (N content) of between 1 and 35% by weight N / polymer unit, preferably between 10 and 33% by weight N / polymer unit, in particular between 20 and 33% by mass. N / polymer unit. Particularly good flexural strengths of the casting core of more than 200 N / cm ² could be achieved in particular with polymeric polyamines having a relatively high amino group density in the range of 30% by weight N / polymer unit, eg with polyvinylamines, which have a nitrogen content of up to 33% by weight. Having polymer unit and in particular with polyvinyl amines having a high proportion of free amino groups, can be achieved.

The amount of polyamine provided as the second binder component is preferably between 0.001 and 1 mass%, in particular between 0.005 and 0.5 mass%, based on polyamine on the particulate material. It is aimed primarily according to the type of polyamine, the amount of In general, the higher the polyamine can be, the lower it can be the free amino group density of the polyamine is the binder properties in terms of bending and abrasion resistance to improve.

The first binder component based on condensed phosphates may contain or consist entirely of polyphosphates, preferably alkali metal polyphosphates, in particular sodium polyphosphate, and / or metaphosphates, preferably alkali metal metaphosphates, in particular sodium metaphosphates, for example sodium hexametaphosphate. Furthermore, it can be provided that the first binder component contains or entirely consists of a water-soluble phosphate glass containing poly- and / or metaphosphate chains, wherein the phosphate glass preferably contains between 58 and 75 mass% phosphorus pentoxide (P ₂ O ₅ ) and between 25 and 42 Mass .-% alkali metal oxide, in particular sodium oxide (Na ₂ O), having. The binders mentioned are known as such and ensure a quick and lump-free dissolution of the casting core when it is immersed in the finished casting in water. Another advantage of this binder is that they lead even with relatively low moisture content to an optimal mixing with the molding sand and thereby ensure a sufficient initial strength of the casting core or the mold, so that only very short drying times required and thus very short cycle times for the production possible are.

The amount of the first binder component based on Condensed phosphates is useful between 0.25 and 25 mass%, preferably between 0.5 and 10 mass%, based on the water-insoluble, particulate material.

In a further development, the invention is characterized by at least one additive, preferably in the form of sulfates, carbonates and / or nitrates from the group of alkali metals and / or alkaline earth metals, such as alkali metal carbonates, in particular sodium carbonate (Na ₂ CO ₃ ). Surprisingly, it has been found that such an additive contributes to a substantial improvement in the temperature resistance of the casting mold or the core to a value above 800 ° C, so that the casting of alloys with a relatively high melting point, for example aluminum alloys, as well as thermoplastics from high-melting polymers becomes possible without deformations of the mold or the casting core occur during the casting process. It has also been found that a proportion of alkali metal carbonates increases the dispersibility of the casting core in water and thus facilitates the gutting of the finished casting. Depending on the required temperature resistance, it is expedient to provide between 20 and 90% by weight, in particular between 30 and 85% by weight, of alkali metal carbonate, based on the first binder component based on condensed phosphates.

In addition to the water-insoluble, particulate material, as foundry sand containing both condensed phosphates as also polyamine-containing binder and optionally the Aggregate, in particular the alkali metal carbonates, contains the molding material mixture for the mold or the Casting core usually still has a moisture content between 0.01 and 35 mass%, in particular between 0.1 and 5 mass%. After drying, the moisture content is the casting mold or the casting core usually about 0.01 mass% or less.

The method according to the invention is characterized that a second binder component based on at least a polyamine is added. These are preferably the types of first and second binder components described above and optionally aggregates in the above used amount described.

A preferred embodiment provides that the second binder component in liquid form with the particulate Material brought into contact and then the first binder component is added in dry form, the Mixture of water is added. The second binder component may be in the liquid phase or as particular aqueous solution are present. Unless an aggregate, such as Alkali metal carbonates, this may be in the dissolved the mixture added water and the solution of Mixture be added.

Another preferred embodiment provides that the first Binder component dry with the particulate material mixed and then an aqueous solution with the second Binder component is added, again, if desired, the aggregate before adding the solution in this can be solved.

Alternatively, it is possible that the binder and optionally the aggregate dissolved in water and the solution with the particulate material is brought into contact. In In any case, the most homogeneous possible distribution of the water-soluble binder and optionally the additive can be achieved with the particulate material.

Appropriately, up to 35 Mass .-% of water based on the added particulate material and becomes the casting mold or the casting core after molding, e.g. except one Residual moisture content of about 0.01% by weight based on the particulate Dried material. The amount of water used is preferably kept as low as possible for short Cycle times in the production to ensure, in turn, significantly depend on the drying time. On the other hand lets the flexural strength of the casting mold or of the casting core within certain limits and influence by the water content the water content ensures the required flowability the mixture when shooting into the box. It has proved to be advantageous between 0.1 and 5 mass%, in particular between about 0.1 and 3% by weight, based on water to add to the particulate material for short cycle times with a satisfactory flowability to provide the molding material mixture.

In further training it is provided that the mixture first dried to a predetermined residual moisture, the mixture then added water again and formed the mixture is at least a portion of the added free Water is removed again. The mixture may preferably initially to a predetermined residual moisture of about 0.1 mass .-% are dried. Let that way the cycle times for the preparation of the invention Further reduce the casting mold or the casting core by the Total amount of added water can be reduced.

Furthermore, the dried to a predetermined residual moisture Formstoffmischung well storable and by the re-addition of water easily processable. Also in In this case, the casting mold or the casting core after the Shaping appropriate to a residual moisture content of about 0.01 wt .-% based on the particulate material dried.

Fig. 1

ein Diagramm zur Veranschaulichung der Biegefestigkeit σ eines Gießkerns mit einem Natriumpolyphosphatbinder ohne Zusatz von Polyaminen (A) und mit Zusatz von 0,1 Mass.-% Polyvinylamin (B) zu verschiedenen Standzeiten t;

Fig. 2

ein Vergleichsdiagramm zur Veranschaulichung der Biegefestigkeit σ eines Gießkerns mit einem Binder ausschließlich aus Polyvinylamin zu verschiedenen Standzeiten t;

Fig. 3

ein Diagramm zur Veranschaulichung der Biegefestigkeit σ eines Gießkerns der Zusammensetzung (B) gemäß Fig. 1, welcher zusätzlich einen Zuschlagstoff in Form von Natriumcarbonat enthält, zu verschiedenen Standzeiten t;

Fig. 4

ein Diagramm zur Veranschaulichung der Biegefestigkeit σ eines Gießkerns der Zusammensetzung gemäß Fig. 3 nach verschiedenen Lagerzeiten t₁ der Formstoffmischung und nach verschiedenen Standzeiten t₂;

Fig. 5

ein Diagramm zur Veranschaulichung der Biegefestigkeit σ je eines Gießkerns mit einem Binder aus Natriumpolyphosphat und verschiedenen Polyaminen mit unterschiedlicher Aminogruppendichte (A, B, C, D, E) zu verschiedenen Standzeiten t und

Fig. 6

ein Diagramm zur Veranschaulichung der Biegefestigkeit σ je eines Gießkerns mit den Zusammensetzungen (A, B, C, D, E) gemäß Fig. 5 nach verschiedenen Lagerzeiten t₁ der Formstoffmischung und nach verschiedenen Standzeiten t₂.

The invention is explained in more detail by means of exemplary embodiments with reference to the drawings. Showing:

Fig. 1

a diagram illustrating the bending strength σ of a casting core with a Natriumpolyphosphatbinder without the addition of polyamines (A) and with the addition of 0.1 Mass .-% polyvinylamine (B) at different service lives t;

Fig. 2

a comparison diagram illustrating the bending strength σ of a casting core with a binder exclusively of polyvinylamine at different service lives t;

Fig. 3

a diagram illustrating the bending strength σ of a casting core of the composition (B) of Figure 1, which additionally contains an additive in the form of sodium carbonate, at different service lives t;

Fig. 4

a diagram illustrating the bending strength σ of a casting core of the composition of Figure 3 after different storage times t _{1 of} the molding material mixture and after different service life t ₂ .

Fig. 5

a diagram illustrating the flexural strength σ each of a casting core with a binder of sodium polyphosphate and various polyamines with different amino group density (A, B, C, D, E) at different service lives t and

Fig. 6

a diagram for illustrating the bending strength σ depending on a casting core having the compositions (A, B, C, D, E) of Fig. 5 after different storage times t ₁ of the molding mixture and after various periods _t2.

Example 1:

Each casting cores were made with the following compositions produced.

Composition A:

• Molding sand,
• 2 Mass .-% sodium polyphosphate based on the molding sand (Binder),
• 1.4% by mass of moisture based on the foundry sand;

Composition B:

• Molding sand,
• 2 Mass .-% sodium polyphosphate (binder component 1) based on the molding sand
• 0.1% by mass of liquid polyvinylamine (binder component 2) based on the molding sand,
• 1.4 Mass .-% moisture based on the molding sand.

For the preparation of the casting core according to composition A was dry mixed with the molding sand of the binder. For the production the casting core according to composition B became the second Binder component in dissolved form homogeneous with the molding sand mixed and the mixture then the first binder component mixed dry. Subsequently, each about 1.4 Mass .-% water based on the foundry sand added. The Molding compound mixture was injected in each case in a core box and to a residual moisture content of about 0.01 mass% dried. The casting cores produced in this way were different Service life t on their flexural strength σ examined.

As can be seen from Fig. 1, the flexural strength σ of the composition A excluding a conventional sodium polyphosphate binder immediately after drying (t = 0) was about 80 N / cm ² . After about two hours (t = 120 min), a substantially constant bending strength σ of about 100 N / cm ^{2 was established} . On the other hand, the flexural strength of composition B, which in addition to the first binder component in the form of sodium polyphosphate contained small amounts of a second binder component in the form of polyvinylamine, was already greater than 150 N / cm ² immediately after drying (t = 0) about four hours (t = 240 min) has set a substantially constant bending strength of more than 200 N / cm ² .

Consequently, the flexural strength of the casting core can be improved by the Addition of only small amounts (0.1% by mass based on the Molding sand) of polyvinylamine are practically doubled.

Example 2:

As a comparative experiment were in the manner described above Casting cores produced, with as binder exclusively polyvinylamine was used. The obtained casting cores were then after different service lives t on their Flexural strength σ investigated.

As can be seen from FIG. 2, immediately after drying (t = 0), a high flexural strength of more than 250 N / cm ^{2 was found} , which after about two hours (t = 120 min) reached a value in the range of 100 N / cm ^{2 has} fallen off. It has also been found that the cores have an elastic behavior with increasing storage time of the molding mixture before shooting into the core box and drying, which can lead to deformation of the cores during the casting process. Consequently, pure polyvinylamine proves to be less suitable as a binder for the molding sand.

Example 3:

Composition B according to Example 1 (molding sand, 2% by mass of sodium polyphosphate (binder component 1), 0.1% by mass of liquid polyvinylamine (binder component 2) and 1.4% by mass of moisture, based in each case on the molding sand) was used Increasing the temperature resistance additionally added sodium carbonate (Na ₂ CO ₃ ) as an additive. Casting cores were produced from the resultant molding material mixture in the manner described above and these were examined for their bending strength σ after various service lives t.

As can be seen from FIG. 3, a bending strength of more than 200 N / cm ² was obtained immediately after drying (t = 0), which dropped slightly for a short time (t = 10 min) and after about two hours (t = 120 min) to a substantially constant value above 200 N / cm ² , which corresponds to the flexural strength of a casting core without the addition of Na ₂ CO ₃ , but with an otherwise corresponding composition (compare Composition B of FIG.

The example shows that the bending strength of the casting core is not impaired by the addition of Na ₂ CO ₃ . However, the addition of Na ₂ CO ₃ gives the casting core a significantly better temperature resistance, so that it is suitable for example for the production of aluminum castings with a casting temperature of about 800 ° C, with deformations of the casting core during the casting process safely and reliably avoided. Moreover, the addition of Na ₂ CO _{3 increases} the water solubility of the foundry core, thus facilitating gutting of the finished casting.

Example 4:

To investigate the shelf life of the molding material mixture for a casting core according to Example 3, foundry sand, 2% by weight of sodium polyphosphate (binder component 1) and 0.1% by weight of liquid polyvinylamine (binder component 2), based in each case on the foundry sand, and sodium carbonate (Na ₂ CO ₃ ) homogeneously mixed with about 1.4 mass .-% of water based on the molding sand. The molding material mixture thus formed was injected after various storage times t ₁ of 0, 1, 2 and 3 h in a core box and dried to a residual moisture content of about 0.01 mass .-% based on the molding sand. The bending strength σ was determined after different service lives t ₂ , namely on the one hand immediately after drying (t ₂ = 0), on the other hand after one day (t ₂ = 24 h).

As can be seen from FIG. 4, for bearing times t _{1 of} the molding material mixture, only slightly worse bending strengths in the range of just below 200 N / cm ^{2 were found} between one hour and three hours than with immediate injection (t ₁ = 0) of the mixture into the core box, which gave a flexural strength of about 220 N / cm ² . The bending strength of the casting core immediately after drying (t ₂ = 0) in all cases corresponded approximately to the flexural strength after a service life of one day (t ₂ = 24 h), which corresponds to the course of the flexural strength shown in FIG. 3.

The example makes it clear that the molding material mixture a good storability identifies and still several hours dried after the mixing process to form the casting core can be.

Example 5:

• Formsand,
• 2 Mass.-% Natriumpolyphosphat bezogen auf den Formsand,
• 0,1 Mass.-% eines Polyamins bezogen auf den Formsand,
• 1,4 Mass.-% Feuchtigkeit.

Each casting cores were produced with the following compositions:

• Molding sand,
• 2% by mass of sodium polyphosphate, based on the molding sand,
• 0.1% by mass of a polyamine based on the molding sand,
• 1.4 mass% moisture.

As polyamines were on the one hand different polyethylenimines (A, B) used, namely water-modified polyethyleneimines with a molecular weight of about 2000 g / mol (A) or 750,000 g / mol (B). On the other hand, polyvinylamines (C, D, E) used with a molecular weight of about 400,000 g / mol, which is due to the proportion of free amino groups differ, which in turn corresponds to the degree of hydrolysis. The polyvinylamine (C) has the highest degree of hydrolysis, the polyvinylamine (E) a lower contrast Degree of hydrolysis and the polyvinylamine (D) the lowest Degree of hydrolysis of polyvinylamines (C, D, E).

The production of the cores was done according to the example 1 described method. Then they were like that produced casting cores after different service lives t examined for their bending strength σ.

Fig. 5 shows that the best flexural strengths could be achieved with the polyvinylamine (C) having a high content of free amino groups. It is believed that the free amino groups of the polyvinylamine interact with the phosphate groups of the sodium polyphosphate and improve its binding properties. From Fig. 5 it is also clear that after a life of about two hours (t = 120 min), a substantially constant bending strength could be achieved, which was at least 200 N / cm ² in the case of polyvinylamine (C).

Example 6:

To study the shelf life of the compositions (A, B, C, D, E) for a casting core according to Example 5, the molding material mixtures were injected into a core box after different storage times t ₁ of 0, 1, 2 and 3 h and dried. The bending strength σ was determined after different service lives t ₂ , namely on the one hand immediately after drying (t ₂ = 0), on the other hand after one day (t ₂ = 24 h).

As can be seen from FIG. 6, the best values for the flexural strength of the casting core were obtained after a storage time t _{1 of} the molding material mixture of one hour, the mixture also being obtained immediately or at least three hours after mixing the but slightly poorer flexural strength Single component was processable, so that also here a good shelf life was found. The polyvinylamine (C) with a high proportion of free amino groups has proven most suitable in all cases. After a service life of the foundry core of one day (t ₂ = 24 h), in each case a bending strength which improved immediately after drying of the mixture (t ₂ = 0) arose, which corresponds to the curve of the flexural strength shown in FIG. 5.

The examples make it clear that through the addition of small amounts of polyamines as an additional binder component to a conventional binder based on sodium polyphosphate the flexural strength of the core is significant can be increased, the flexural strength also by the addition of an additive in the form of sodium carbonate to improve the temperature resistance of the Casting core is not affected. The mixture has a good shelf life and water solubility and therefore a perfect processability.

Claims (36)

1. Water-dispersible casting mould, particularly core, for the manufacture of castings, comprising

   a water-insoluble, particulate material, particularly moulding sand,

   a binder, having as a first binder component at least one condensed phosphate,

   wherein the binder has as a second binder
   component at least one polyamine.
2. Mould according to claim 1, wherein the polyamine is chosen from the group of polymeric polyamines.
3. Mould according to claim 1 or 2, wherein the polyamine is chosen from the group of polyethylene imines, polyvinyl amines and/or their copolymers.
4. Mould according to claims 2 or 3, wherein the polyamine has a nitrogen proportion between 1 and 35 wt.% N/polymer unit.
5. Mould according to one of the claims 2 to 4, wherein the polyamine has a nitrogen proportion between 10 and 33 wt.% N/polymer unit.
6. Mould according to one of the claims 2 to 5, wherein the polyamine has a nitrogen proportion between 20 and 33 wt.% N/polymer unit.
7. Mould according to one of the claims 1 to 6, wherein there are between 0.001 and 1 wt.% polyamine, based on the particulate material.
8. Mould according to one of the claims 1 to 7, wherein there are between 0.005 and 0.5 wt.% polyamine, based on the particulate material.
9. Mould according to one of the claims 1 to 8, wherein the first binder component comprises or entirely consists of a polyphosphate.
10. Mould according to claim 9, wherein the polyphosphate is an alkali metal polyphosphate, particularly sodium polyphosphate.
11. Mould according to one of the claims 1 to 8, wherein the first binder component comprises or entirely consists of a metaphosphate.
12. Mould according to claim 11, wherein the metaphosphate is an alkali metal metaphosphate, particularly sodium metaphosphate.
13. Mould according to one of the claims 1 to 8, wherein the first binder component comprises or entirely consists of a polyphosphate and/or metaphosphate chain-containing, water-soluble phosphate glass.
14. Mould according to claim 13, wherein the phosphate glass contains between 58 and 75 wt.% phosphorus pentoxide (P₂O₅) and between 25 and 42 wt.% alkali metal oxide, particularly sodium oxide (Na₂O).
15. Mould according to one of the claims 1 to 14, wherein there are between 0.25 and 27 wt.% of the first binder component, based on the particulate material.
16. Mould according to one of the claims 1 to 15, wherein there are between 0.5 and 10 wt.% of the first binder component, based on the particulate material.
17. Mould according to one of the claims 1 to 16, wherein by at least one flux, preferably in the form of sulphates, carbonates and/or nitrates from the group of alkali metals and/or alkaline earth metals, such as alkali metal carbonates, particularly sodium carbonate (Na₂CO₃).
18. Mould according to claim 17, wherein there are between 20 and 90 wt.% alkali metal carbonate, based on the first binder component.
19. Mould according to claim 17 or 18, wherein there are between 30 and 85 wt.% alkali metal carbonate, based on the first binder component.
20. Mould according to one of the claims 1 to 19, wherein by a moisture proportion of the moulding material mixture between 0.01 and 35 wt.%, based on the particulate material.
21. Mould according to claim 20, wherein the moisture proportion of the moulding material mixture is between 0.1 and 5 wt.%, based on the particulate material.
22. Method for the manufacture of a water-dispersible casting mould, particularly core, for the manufacture of castings, in that a water-insoluble, particulate material, particularly moulding sand, is mixed, accompanied by the addition of water, with a binder having as a first binder component at least one condensed phosphate, the mixture is moulded and at least part of the added free water is removed, wherein a second binder component based on at least one polyamine is added.
23. Method according to claim 22, wherein a polyamine according to one of the claims 2 to 6 is added.
24. Method according to claim 22 or 23, wherein the polyamine is used in a quantity between 0.001 and 1 wt.%, particularly between 0.005 and 0.5 wt.%, based on the particulate material.
25. Method according to one of the claims 22 to 24, wherein a first binder component according to one of the claims 9 to 14, is used.
26. Method according to one of the claims 22 to 25, wherein the first binder component is used in a quantity between 0.25 and 25 wt.%, particularly between 0.5 and 10 wt.%, based on the particulate material.
27. Method according to one of the claims 22 to 26, wherein use is made of at least one flux, preferably in the form of sulphates, carbonates and/or nitrates from the group of alkali metals and/or alkaline earth metals, such as alkali metal carbonates, particularly sodium carbonate (Na₂CO₃).
28. Method according to claim 27, wherein the alkali metal carbonate is used in a quantity between 20 and 90 wt.%, particularly between 30 and 85 wt.%, based on the first binder component.
29. Method according to one of the claims 22 to 28, wherein the second binder component in liquid form is brought into contact with the particulate material and then the first binder component is admixed in dry form, water being added to the mixture.
30. Method according to claim 27, wherein the flux is dissolved in water and the solution is added to the mixture.
31. Method according to one of the claims 22 to 28, wherein the first binder component is mixed dry with the particulate material and then an aqueous solution is added with the second binder component.
32. Method according to claim 31, wherein prior to the addition of the solution, a flux is dissolved in the latter.
33. Method according to claim 27 or 28, wherein all the binder components and optionally a flux are dissolved in water and the solution is contacted with the particulate material.
34. Method according to one of the claims 22 to 33, wherein up to 35 wt.% water, based on the particulate material, are added.
35. Method according to one of the claims 22 to 34, wherein the mixture is initially dried to a predetermined residual moisture content, the mixture is then again mixed with water and the mixture is moulded and at least part of the added free water is removed again.
36. Method according to claim 35, wherein the mixture is initially dried to a predetermined residual moisture content of approximately 0.1 wt.%.

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