EP3548200B1 - Amino acid-containing moulding material mixture for production of mouldings for the foundry industry - Google Patents

Description

The present invention relates to a molding material mixture for the production of moldings for the foundry industry, moldings for the foundry industry, a use of amino acids in a molding material mixture for producing moldings for the foundry industry or for producing moldings for the foundry industry, a method for producing a molding material mixture and a Process for the production of a molded body for the foundry industry.

In the foundry industry, molten materials, ferrous metals or non-ferrous metals are converted into shaped objects with certain workpiece properties. For the shaping of the cast pieces, first of all, very complicated casting molds for receiving the molten metal have to be produced. The casting molds are divided into lost molds, which are destroyed after each casting, and permanent molds, each of which can be used to produce a large number of castings. The lost molds usually consist of a refractory, pourable molding material that is solidified with the help of a hardenable binder.

Molds are negatives that contain the cavity to be poured, which results in the casting to be manufactured. When making the mold, a model of the to finished casting, the cavity is formed in the molding material. Inner contours are represented by cores that are formed in a separate core box.

Both organic and inorganic binders, which can be hardened by cold or hot processes, can be used to produce the casting molds. Cold processes are processes in which curing takes place essentially at room temperature without heating the molding material mixture. The hardening usually takes place through a chemical reaction, which can be triggered, for example, by passing a gaseous catalyst through the molding material mixture to be hardened or by adding a liquid catalyst to the molding material mixture. In hot processes, the molding material mixture is heated to a sufficiently high temperature after molding, for example to drive off the solvent contained in the binder or to initiate a chemical reaction through which the binder is cured by crosslinking.

The production of the casting molds can proceed in such a way that the filler is first mixed with the binder system so that the grains of the refractory filler are coated with a thin film of the binder system. The molding material mixture obtained from filler and binder system can then be introduced into a corresponding mold and, if necessary, compacted in order to achieve sufficient stability of the casting mold. The casting mold is then cured. If the casting mold has at least reached a certain initial strength, it can be removed from the mold.

At present, organic binders, such as. B. polyurethane, furan resin, phenol or urea-formaldehyde resins are used, in which the curing of the binder takes place by adding a catalyst.

Processes in which the molding material mixture is cured by heat or by the subsequent addition of a catalyst have the advantage that the processing of the molding material mixture is not subject to any particular time restrictions. The molding material mixture can initially be produced in larger quantities, which are then processed over a longer period of time, usually several hours. The molding material mixture does not harden until after it has been molded, with the aim being to achieve a rapid reaction. The casting mold can be removed from the mold immediately after it has hardened, so that short cycle times can be achieved.

So-called "no-bake binders" are mostly used in the production of casting molds for large castings, for example engine blocks for marine diesel engines or large machine parts such as the hubs of rotors for wind power plants. In the "no-bake process", the refractory mold base material (e.g. sand) is often first coated with a catalyst (hardener), then the binder is added and, by mixing, it is evenly distributed over the grains of the refractory mold base material that have already been coated with catalyst. In this process, so-called continuous mixers are often used. The resulting molding material mixture can then be shaped into a molded body. Since the binder and catalyst are evenly distributed in the molding material mixture, the curing takes place largely evenly, even with large moldings.

Alternatively, with the "no-bake process", the refractory molding base material (e.g. sand) can first be mixed with the binder and then the hardener added. In this process, especially when producing casting molds for large castings, partial hardening or crosslinking of the binder can occur due to a partial, local excessively high concentration of the hardener, which would result in an inhomogeneous molding material.

The "classic" no-bake binders are often based on furan resins or phenolic resins or furan / phenolic resins. They are often offered as systems (kits), one component comprising a reactive furan resin or phenolic resin or furan / phenolic resin and the other component an acid, the acid acting as a catalyst for curing the reactive resin component.

Furan and phenolic resins show very good disintegration properties when cast. The furan or phenolic resin decomposes under the action of heat from the liquid metal and the strength of the casting mold is lost. After casting, cores can therefore be removed from cavities, if necessary after previously shaking the casting.

"Furan no-bake binders" contain reactive furan resins, which regularly include furfuryl alcohol as an essential component. Furfuryl alcohol can react with itself under acid catalysis and form a homopolymer. For the production of furan no-bake binders, furfuryl alcohol is generally not used on its own, but other compounds, such as formaldehyde, are added to the furfuryl alcohol and are polymerized into the resin. Further components can be added to the resins, which influence the properties of the resin, for example its elasticity. Melamine and urea can be added, for example, in order to still bind free formaldehyde.

Furan no-bake binders are usually produced by first generating precondensates from, for example, urea, formaldehyde and furfuryl alcohol under acidic conditions. These precondensates are then diluted with furfuryl alcohol.

It is also conceivable that urea and formaldehyde can react alone. This creates so-called UF resins ("urea formaldehyde" resins, "aminoplasts"). These are usually then diluted with furfuryl alcohol. Advantages of this production method are a higher flexibility / variability in the product range and lower costs, since the cold mixing processes are involved.

Resoles can also be used to produce furan / phenol no-bake binders. Resoles are made by polymerizing mixtures of phenol and formaldehyde. These resoles are then often diluted with a large amount of furfuryl alcohol.

Furan no-bake binders are hardened with an acid. This acid catalyzes the crosslinking of the reactive furan resin. It should be noted that the hardening can be controlled via the amount of acid, whereby the amount of acid required to set a hardening time depends on the binder and is influenced by factors such as the pH of the binder and the type of acid.

Aromatic sulfonic acids, phosphoric acid, methanesulfonic acid and sulfuric acid are often used as acids. In some special cases, combinations thereof are used, inter alia, in combination with other carboxylic acids. Certain "hardening moderators" can also be added to the furan no-bake binder.

Phenolic resins, the second large group of acid-catalyzed curable no-bake binders, contain resols as reactive resin components, i.e. phenolic resins that have been produced with a molar excess of formaldehyde. Compared to furan resins, phenolic resins are less reactive and require strong sulfonic acids as catalysts.

For some time now, no-bake binders have been used for the production of molds and cores for large and single castings. These cold-curing systems are mostly reaction products of formaldehyde with furfuryl alcohol, phenol and / or urea.

Molding mixtures based on formaldehyde usually have very good properties. In particular, phenol / furan / formaldehyde mixed resins, urea / formaldehyde resins and furan / formaldehyde resins are frequently used in the foundry industry.

U.S. 3,644,274 primarily relates to a no-bake process using certain mixtures of acid catalysts for curing furfuryl alcohol-formaldehyde-urea resins.

U.S. 3,806,491 relates to binders that can be used in the "no-bake" process. The binders used there include products from the reaction of paraformaldehyde with certain ketones in a basic environment as well as furfuryl alcohol and / or furan resins.

U.S. 5,491,180 describes resin binders that are suitable for use in the no-bake process. The binders used there are based on 2,5-bis (hydroxymethyl) furan or methyl or ethyl ethers of 2,5-bis (hydroxymethyl) furan, the binders containing 0.5 to 30% by weight of water and usually a high proportion of furfuryl alcohol.

EP 0 540 837 suggests low-emission, cold-curing binders based on furan resins and lignin from the Organosolv process. The furan resins described there contain a high proportion of monomeric furfuryl alcohol.

DE 198 56 778 describes cold resin binders which are produced by reacting an aldehyde component, a ketone component and a component consisting essentially of furfuryl alcohol.

EP 1 531 018 relates to no-bake foundry binder systems made from a furan resin and certain acid hardeners. The binder systems described therein preferably comprise 60 to 80% by weight of furfuryl alcohol.

US 2016/0 158 828 A1 describes the production of casting molds using a rapid prototyping process. The molding material mixtures described in the document can contain A) at least one refractory filler and B) a binder system, wherein the binder system can contain i) formaldehyde and ii) a thermoset, a saccharide, a synthetic polymer, a salt, a protein or an inorganic polymer .

EP 1 595 618 B1 describes a method for making a ceramic mask shape. A casting slip containing ceramic particles, a binder and a liquefier is used to produce the mold. The liquefier can be amino acids, ammonium polyacrylates or tri-acid carboxyls with alcohol groups.

DE 600 05 574 T2 relates to a method for the production of thermal insulation bodies. The thermal insulation bodies described in the documents comprise mineral wool and a binder based on a formaldehyde-phenolic resin.

U.S. 3,296,666 A describes a method for making casting molds. In the document synthetic resin materials, natural resins, rubber, proteins, carbohydrates or egg white are used as alternative binders to phenol-formaldehyde resins.

U.S. 5,320,157 A describes a process for producing a core, the molding material mixture used to produce the core containing gelatin as a binder.

DE 23 53 642 A1 discloses a binder based on phenol-formaldehyde condensation products for use in hot-setting molding compounds, in particular in foundry molding compounds by the shell molding process, the phenol-formaldehyde condensation product having an additional content of aminocarboxylic acids or aminosulfonic acids.

JP 3175045B discloses a phenol-formaldehyde binder for the shell molding process, the binder containing an amino acid or an alkali metal salt, alkaline earth metal salt, hydrochloride, sulfate, or alkyl ester of an amino acid as a disintegration promoter.

GB 1,075,619 A relates to a process for the production of molds and cores and a molding material mixture for this process.

In the production of moldings (such as feeders, foundry molds or cores) for the foundry industry, it is advantageous if the binder system has a high strength after curing. Good strengths are particularly important for the production of complex, thin-walled moldings and their safe handling.

The present invention was therefore based on the object of providing a molding material mixture which can be used to produce moldings for the foundry industry and which is distinguished by improved strength.

1. A) einen oder mehrere schüttfähige, feuerfeste Füllstoffe, und
2. B) ein Bindemittelsystem, umfassend
   1. i) Formaldehyd, einen Formaldehydspender und/oder Vorkondensate aus Formaldehyd, wobei das Bindemittel zusätzlich Furanderivate und/oder Furfurylalkohol oder Vorkondensate aus Furanderivaten und/oder Furfurylalkohol umfasst,
      und
   2. ii) eine Aminosäure ausgewählt aus der Gruppe bestehend aus Glycin, Glutamin, Alanin, Valin und Serin.

According to the invention, this object was achieved by a molding material mixture for the production of moldings for the foundry industry

1. A) one or more pourable, refractory fillers, and
2. B) comprising a binder system
   1. i) formaldehyde, a formaldehyde donor and / or precondensates made from formaldehyde, the binder additionally comprising furan derivatives and / or furfuryl alcohol or precondensates made from furan derivatives and / or furfuryl alcohol,
      and
   2. ii) an amino acid selected from the group consisting of glycine, glutamine, alanine, valine and serine.

It has surprisingly been found that moldings for the foundry industry have an improvement in strength when they are produced from a molding material mixture according to the invention. The addition of an amino acid to a binder system that has formaldehyde, a formaldehyde donor and / or precondensates from formaldehyde, surprisingly improved the strength of the molded article produced from it, compared to molded articles made from molding mixtures of the same composition under identical conditions, but without the addition of an amino acid were manufactured.

Surprisingly, it has also been found that moldings which are produced from a molding material mixture according to the invention are additionally distinguished by a lower content of free formaldehyde. Formaldehyde has a pungent odor and is toxic in high concentrations. It is therefore advantageous if moldings have less free formaldehyde and no formaldehyde is released into the environment. Otherwise, there is a risk that the maximum workplace concentration (MAK) for formaldehyde will be exceeded, particularly when many shaped bodies are stored in a confined space. The emission of formaldehyde from a molding material mixture according to the invention before and during curing can surprisingly also be reduced by adding amino acids.

In order to reduce the content of free formaldehyde in molding mixtures or in moldings produced from the molding mixtures, it would of course also be possible to add less formaldehyde, formaldehyde donors and / or precondensates from formaldehyde to the binder system. However, this would lead to a significant deterioration in the properties (in particular the strength) of the molded bodies produced from the molding material mixtures.

In order to reduce the concentration of free formaldehyde in molding mixtures or in moldings produced from the molding mixtures, urea has traditionally been used as a formaldehyde scavenger. Compared to urea, however, amino acids also have the advantage that the nitrogen content in the molding material mixture or in the molded articles produced therefrom can be reduced, since the amino acids according to the invention are more effective formaldehyde scavengers. In addition, when using urea, no significant improvement but rather a reduction in strength can be observed. In addition, when urea is used as a formaldehyde scavenger, it is not uncommon for reaction products to be formed that are not stable when mixed and lead to cloudiness and precipitation.

In particular in iron and steel casting, especially in stainless steel casting, the lowest possible total nitrogen content is desirable, since nitrogen can lead to casting defects. For use in cast steel and gray cast iron, a binder should have the lowest possible total nitrogen content, since surface defects, for example so-called "pinholes" (pinholes), occur as casting defects due to a high nitrogen content.

According to the invention, the molded bodies for the foundry industry are feeders, foundry molds or cores for the foundry industry.

All granular fillers commonly used for the production of moldings (in particular feeders, foundry molds and cores) for the foundry industry, e.g. quartz sand and special sands, can be used as pourable, refractory fillers. The term special sand includes natural mineral sands as well as sintered and melted products that are manufactured in granular form or converted into granular form by crushing, grinding and classifying processes, or inorganic mineral sands produced by other physico-chemical processes that are used as basic molding materials with conventional foundry binders for used in the manufacture of feeders, cores and molds.

According to a preferred embodiment of the present invention, a molding material mixture according to the invention is particularly preferred, the one, at least one of the several or all pourable, refractory fillers being selected from the group consisting of quartz sand, quartz sand, olivine sand, chromium-magnesite granules, aluminum silicates, in particular J-sand and kerphalite, heavy minerals, in particular chromite, zircon sand and R-sand, technical ceramics, in particular Cerabeads, chamotte, M-sand, Alodur, bauxite sand and silicon carbide, sands containing feldspar, andalusite sands, hollow spherical corundum, spheres made from fly ash, rice husk ash, expanded glasses, foam glasses, expanded perlites, core / shell particles, microspheres, fly ash and other special sands.

Molding material mixtures are preferred according to the invention, wherein the one, at least one of the several or all of the pourable, refractory fillers have an average particle diameter d50 in the range between 0.001 and 5 mm, preferably in the range from 0.01 to 3 mm, particularly preferably in the range from 0, 02 to 2.0 mm. The mean particle diameter d50 is determined in accordance with DIN 66165-2, F and DIN ISO 3310-1.

Molding material mixtures are also preferred according to the invention, the ratio of the total mass of pourable, refractory fillers to the total mass of other constituents of the molding material mixture in the range from 100: 5 to 100: 0.1, preferably from 100: 3 to 100: 0.4, particularly preferred is from 100: 2 to 100: 0.6.

Molding material mixtures according to the invention are also preferred, the bulk density of a mixture of all solids in the molding material mixture being 100 g / L or greater, preferably 200 g / L or greater, particularly preferably 1000 g / L or greater.

• (a) Phenole, insbesondere Phenol, o-Kresol, p-Kresol, 3,5-Xylenol oder Resorcin, oder Vorkondensate aus Phenolen, insbesondere Resole,
  und/oder
• (c) Harnstoff oder Harnstoffderivate oder Vorkondensate aus Harnstoff oder Harnstoffderivaten.

Molding material mixtures are preferred according to the invention, the binder system additionally comprising:

• (a) Phenols, especially phenol, o-cresol, p-cresol, 3,5-xylenol or resorcinol, or precondensates of phenols, especially resoles,
  and or
• (c) Urea or urea derivatives or precondensates from urea or urea derivatives.

In a preferred embodiment of the present molding material mixture according to the invention, the binder system is mixed with a hardener during the production of the moldings offset, which initiates the hardening of the binder. The hardener is usually acids, preferably at least one organic or inorganic acid, particularly preferably an aromatic sulfonic acid (especially para-toluenesulfonic and / or xylene sulfonic acid), phosphoric acid, methanesulfonic acid, sulfuric acid, one or more carboxylic acids or mixtures thereof.

In an alternative preferred embodiment, molding material mixtures according to the invention are particularly preferred, the binder system being thermally curable.

Molding material mixtures according to the invention are particularly preferred, the binder additionally (a) phenols, in particular phenol, o-cresol, p-cresol, 3,5-xylenol or resorcinol, or precondensates of phenols, especially resols, and (b) furan derivatives and / or Furfuryl alcohol or precondensates from furan derivatives and / or furfuryl alcohol. This creates phenol / furfuryl alcohol / formaldehyde resin-bound molding materials during curing. It is therefore preferred according to the invention if the binder system can be hardened to a phenol / furfuryl alcohol / formaldehyde resin, particularly preferably to a high-polymer and solid phenol / furfuryl alcohol / formaldehyde resin. According to the invention, these systems are preferably cured by adding a hardener, the hardener being an organic or inorganic acid, particularly preferably an aromatic sulfonic acid (in particular para-toluene or xylene sulfonic acid or mixtures of para-toluene and xylene sulfonic acid), phosphoric acid, methanesulfonic acid, Sulfuric acid, one or more carboxylic acids or mixtures of the acids mentioned above.

In molding material mixtures according to the invention, the binder additionally comprises furan derivatives and / or furfuryl alcohol or precondensates of furan derivatives and / or furfuryl alcohol. This creates furfuryl alcohol / formaldehyde resin-bound molding materials during curing. The binder system can thus be hardened to a furfuryl alcohol / formaldehyde resin, preferably hardenable to a high-polymer and solid furfuryl alcohol / formaldehyde resin.

Molding material mixtures according to the invention are particularly preferred, the binder additionally comprising i) urea or urea derivatives or precondensates of urea or urea derivatives and ii) furan derivatives and / or furfuryl alcohol or precondensates of furan derivatives and / or furfuryl alcohol. This results in molded materials bound with urea / furfuryl alcohol / formaldehyde resin during hardening. It is therefore preferred according to the invention if the binder system can be hardened to a urea / furfuryl alcohol / formaldehyde resin, preferably to a highly polymeric and solid urea / furfuryl alcohol / formaldehyde resin. According to the invention, these systems are preferably cured by heating in the presence of a latent hardener (warm box) or by adding a hardener, the hardener being an organic or inorganic acid, particularly preferably an aromatic sulfonic acid (in particular para-toluene or xylene sulfonic acid or mixtures of para Toluene and xylene sulfonic acid), phosphoric acid, methanesulfonic acid, sulfuric acid, one or more carboxylic acids or mixtures of the aforementioned acids.

Molding material mixtures according to the invention are particularly preferred, the binder additionally i) urea or urea derivatives or precondensates of urea or urea derivatives, ii) furan derivatives and / or furfuryl alcohol or precondensates of furan derivatives and / or furfuryl alcohol and iii) phenols, in particular phenol, o-cresol, p -Cresol, 3,5-xylenol or resorcinol, or precondensates of phenols, in particular resoles. As a result, urea / furfuryl alcohol / phenol / formaldehyde resin-bound molding materials are produced during curing. It is therefore preferred according to the invention if the binder system can be hardened to a urea / furfuryl alcohol / phenol / formaldehyde resin, preferably to a highly polymeric and solid urea / furfuryl alcohol / phenol / formaldehyde resin. According to the invention, these systems are preferably cured by heating in the presence of a latent hardener (warm box) or by adding a hardener, with the hardener is an organic or inorganic acid, particularly preferably an aromatic sulfonic acid (in particular para-toluene or xylene sulfonic acid or mixtures of para-toluene and xylene sulfonic acid), phosphoric acid, methanesulfonic acid, sulfuric acid, one or more carboxylic acids or mixtures of the aforementioned acids .

1. i) Phenol/Furfurylalkohol/Formaldehydharz,
2. ii) Furfurylalkohol/Formaldehydharz,
3. iii) Harnstoff/Furfurylalkohol/Formaldehydharz
   oder
4. iv) Harnstoff/Furfurylalkohol/Phenol/Formaldehydharz

Molding material mixtures are therefore preferred according to the invention, the binder system being curable into one

1. i) phenol / furfuryl alcohol / formaldehyde resin,
2. ii) furfuryl alcohol / formaldehyde resin,
3. iii) urea / furfuryl alcohol / formaldehyde resin
   or
4. iv) urea / furfuryl alcohol / phenol / formaldehyde resin

In molding mixtures according to the invention, the amino acid is selected from the group consisting of glycine, glutamine, alanine, valine and serine.

Our own studies have shown that the amino acids glycine, glutamine, alanine, valine and serine in particular have good properties when used in molding material mixtures according to the invention. By adding these amino acids, the strength of the molded bodies produced from the molding material mixtures can be improved particularly well without other properties of the molded bodies produced or of the molding material mixture being impaired. In addition, the content of free formaldehyde in the molding material mixture and in the moldings produced from the molding material mixture can be reduced. Of the amino acids, glycine is particularly preferred. Molding material mixtures according to the invention are preferred, the amino acid being an α-amino acid.

A molding material mixture according to the invention is likewise preferred, the proportion of all amino acids in the molding material mixture being 0.005 to 5.0% by weight, preferably 0.01 to 2.0% by weight, particularly preferably 0.03 to 1.0 % By weight, based on the solids content of the entire molding material mixture.

It has been shown in our own investigations that molding material mixtures according to the invention have particularly good properties when the proportion of all amino acids in the molding material mixture is in the ranges listed above. If the proportions of amino acids in the molding material mixture are too low, there is the possibility that the strength of the molded bodies produced from the molding material mixtures is not sufficiently improved and / or that the amount of free formaldehyde is not reduced. If the proportions of amino acids are too high, no further improvement in the properties can be observed.

A molding material mixture according to the invention is likewise preferred, the molar ratio of all amino acids to available formaldehyde being 4: 1 to 1: 0.5, preferably 3: 1 to 1: 0.9, particularly preferably 2.5: 1 to 1: 1 .

Our own studies have shown that molding material mixtures according to the invention have particularly good properties when the molar ratio of all amino acids to available formaldehyde is in the ranges given above. In particular, the strength of the moldings produced from the molding mixtures and the proportion of free formaldehyde in the molding mixtures or the moldings produced therefrom show particularly good properties in the specified ranges.

A molding material mixture according to the invention is also preferred, the formaldehyde donors and / or precondensates of formaldehyde being selected from the group consisting of paraformaldehyde, hexamethylenetetramine, trioxane, methylolamine and methylolamine derivatives such as trimethylolmelamine or hexamethylolmelamine.

In a preferred embodiment of the present invention, the molding material mixture does not contain any proteins or peptides, such as dipeptides, tripeptides, tetrapeptides, pentapeptides or higher-value peptides). It has also been shown that there are advantages if the amino acid used is glycine, glutamine, alanine, valine and / or serine instead of aspartic acid.

Another aspect of the present invention relates to moldings for the foundry industry produced using a molding material mixture according to the invention.

1. i) Phenol/Furfurylalkohol/Formaldehydharz,
2. ii) Furfurylalkohol/Formaldehydharz,
3. iii) Harnstoff/Furfurylalkohol/Formaldehydharz
   oder
4. iv) Harnstoff/Furfurylalkohol/Phenol/Formaldehydharz ist.

A shaped body according to the invention is likewise preferred, the one or more pourable, refractory fillers being bound with a hardened binder and the hardened binder

1. i) phenol / furfuryl alcohol / formaldehyde resin,
2. ii) furfuryl alcohol / formaldehyde resin,
3. iii) urea / furfuryl alcohol / formaldehyde resin
   or
4. iv) urea / furfuryl alcohol / phenol / formaldehyde resin.

• b) Furanderivaten und/oder Furfurylalkohol oder Vorkondensaten aus Furanderivaten und/oder Furfurylalkohol
  und gegebenenfalls
• (a) Phenolen, insbesondere Phenol, o-Kresol, p-Kresol, 3,5-Xylenol oder Resorcin, oder Vorkondensaten aus Phenolen, insbesondere Resole,
  und/oder
• (c) Harnstoff oder Harnstoffderivaten oder Vorkondensate aus Harnstoff oder Harnstoffderivaten .

A shaped body according to the invention is preferred, the shaped body being formed by curing the binder system, a chemical reaction taking place between formaldehyde and / or a precondensate of formaldehyde and

• b) furan derivatives and / or furfuryl alcohol or precondensates from furan derivatives and / or furfuryl alcohol
  and if necessary
• (a) Phenols, in particular phenol, o-cresol, p-cresol, 3,5-xylenol or resorcinol, or precondensates of phenols, especially resoles,
  and or
• (c) Urea or urea derivatives or precondensates from urea or urea derivatives.

Another aspect of the present invention relates to the use of amino acids (a) in a molding material mixture for the production of moldings for the foundry industry or (b) for the production of moldings for the foundry industry.

Another aspect of the present invention relates to the use of at least one amino acid in a molding material mixture for the foundry industry, the molding material mixture containing formaldehyde or a source of formaldehyde in addition to the amino acid. The amino acid is selected from the group consisting of glycine, glutamine, alanine, valine and serine.

Another aspect of the present invention relates to the use of at least one amino acid for the production of moldings with improved strength and / or reduced tendency to casting defects.

Another aspect of the present invention relates to the use of molding material mixtures according to the invention for the production of moldings for the foundry industry.

1. a) Herstellen oder Bereitstellen von einem oder mehreren schüttfähigen, feuerfesten Füllstoffen,
2. b) Herstellen oder Bereitstellen eines Bindemittelsystems, umfassend
   1. i) Formaldehyd, einen Formaldehydspender und/oder Vorkondensate aus Formaldehyd, wobei das Bindemittel zusätzlich Furanderivate und/oder Furfurylalkohol oder Vorkondensate aus Furanderivaten und/oder Furfurylalkohol umfasst,
      und
   2. ii) eine Aminosäure ausgewählt aus der Gruppe bestehend aus Glycin, Glutamin, Alanin, Valin und Serin,
      und
3. c) Vermischen aller Komponenten.

Another aspect in connection with the present invention relates to a method for producing a molding material mixture according to the invention, comprising the following steps:

1. a) Production or provision of one or more pourable, refractory fillers,
2. b) producing or providing a binder system, comprising
   1. i) formaldehyde, a formaldehyde donor and / or precondensates made from formaldehyde, the binder additionally comprising furan derivatives and / or furfuryl alcohol or precondensates made from furan derivatives and / or furfuryl alcohol,
      and
   2. ii) an amino acid selected from the group consisting of glycine, glutamine, alanine, valine and serine,
      and
3. c) Mixing all components.

1. i) Herstellen oder Bereitstellen einer erfindungsgemäßen Formstoffmischung, vorzugsweise mittels eines erfindungsgemäßen Verfahrens zur einer erfindungsgemäßen Formstoffmischung,
2. ii) Formen der Formstoffmischung zu einem ungehärteten Formkörper
   und
3. iii) Aushärten oder Aushärtenlassen des ungehärteten Formkörpers, sodass ein Formkörper für die Gießereiindustrie resultiert.

Another aspect in connection with the present invention relates to a method for producing a molded body for the foundry industry, comprising the following steps:

1. i) producing or providing a molding material mixture according to the invention, preferably by means of a method according to the invention for a molding material mixture according to the invention,
2. ii) Shaping the molding material mixture into an uncured molded body
   and
3. iii) curing or allowing the uncured molded body to harden, so that a molded body for the foundry industry results.

In a preferred embodiment of the method according to the invention for producing a molded body for the foundry industry, the uncured molded body is hardened or allowed to harden by heating.

In an alternative preferred embodiment of the method according to the invention for producing a molded body for the foundry industry, the curing or allowing it to cure takes place by adding a hardener during the production or provision of the molding material mixture according to the invention. The hardener is preferably an organic or inorganic acid, particularly preferably a sulfonic acid (especially para-toluenesulfonic acid), phosphoric acid, methanesulfonic acid, carboxylic acid and / or sulfuric acid or mixtures thereof.

1. I) ein Bindemittelsystem wie weiter oben für eine erfindungsgemäße Formstoffmischung definiert,
2. II) einen Härter, vorzugsweise eine organische oder anorganische Säure, besonders bevorzugt eine aromatische Sulfonsäure (insbesondere para-Toluolsulfonsäure), Phosphorsäure, Carbonsäure, Methansulfonsäure und/oder Schwefelsäure oder Mischungen daraus
   und
3. III) optional einen oder mehrere schüttfähige, feuerfeste Füllstoffe.

Another aspect in connection with the present invention relates to a kit for producing a molding material mixture according to the invention and / or for producing a molding according to the invention for the foundry industry, preferably for the production of feeders, foundry molds or cores for the foundry industry

1. I) a binder system as defined above for a molding material mixture according to the invention,
2. II) a hardener, preferably an organic or inorganic acid, particularly preferably an aromatic sulfonic acid (especially para-toluenesulfonic acid), phosphoric acid, carboxylic acid, methanesulfonic acid and / or sulfuric acid or mixtures thereof
   and
3. III) optionally one or more pourable, refractory fillers.

Within the scope of the present invention, several of the aspects identified above as preferred are preferably implemented simultaneously; The combinations of such aspects and the corresponding features resulting from the appended claims are particularly preferred.

The present invention is explained in more detail below on the basis of selected examples.

Examples: Example 1 (according to the invention): Production of a binder system:

To 100 g of a commercially available phenol-furan cold resin from Hüttenes-Albertus with the designation XA20 (furfuryl alcohol: 78%, free phenol: 4.5%, water content: 2%, free formaldehyde content: 0.171% (corresponding to 5.7 mmol); available from Hüttenes-Albertus Chemische Werke GmbH), 0.43 g of glycine (5.7 mmol) was added at a temperature of 40 ° C. and the mixture was stirred for 60 minutes. After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.09%.

Production of a molding material mix:

At room temperature (18-22 ° C) and a relative humidity (RH) of 40-55%, 100 parts by weight of quartz sand H32 (Quarzwerke Frechen) were added to a laboratory mixer (BOSCH), with 0.5 parts by weight of hardener (Aktivator 100 SR; para -Toluenesulfonic acid 65%, <0.5% H ₂ SO ₄ ) and mixed for 30 seconds. Then 1.0 part by weight of the binder system prepared was added and mixed for a further 45 seconds. The temperature of the molding material mixture produced was 18-22 ° C.

Production of (test) moldings:

The molding material mixture was then introduced by hand into a test bar mold and compacted with a hand plate. Cuboid test bars with the dimensions 220 mm x 22.36 mm x 22.36 mm, so-called Georg Fischer test bars, were produced as test specimens.

Determination of the processing (WT) and curing time (ST):

To determine the processing (WT) and curing time (ST) of the molding material mixture, the setting behavior was observed using a Georg Fischer test bar with the test pin in accordance with VDG leaflet P 72.

Determination of the flexural strength value:

The respective flexural strength values were determined in accordance with VDG data sheet P 72. To determine the flexural strengths, the test bars were placed in a Georg Fischer strength tester equipped with a three-point bending device (DISA-Industrie AG, Schaffhausen, CH), and the force that led to the breakage of the test bars was measured.

The flexural strengths were determined after one hour, after two hours, after four hours and after 24 hours after the manufacture of the (test) moldings to be tested (storage of the cores after removal from the mold in each case at room temperature 18-22 ° C, relative humidity (20-55 ° C) %) measured.

The values determined are summarized in Table 1.

The (test) moldings according to the invention produced from the molding material mixture according to the invention show improved flexural strength after 24 hours compared with the (test) moldings produced according to Comparative Examples 1 and 2, without the setting behavior being adversely affected. In addition, the content of free formaldehyde in the binder system according to the invention is lower than the content of free formaldehyde in the binder systems according to Comparative Examples 1 and 2.

Example 2 (according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 1. However, 5.7 mmol of alanine were used instead of glycine.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.08%.

Example 3 (according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 1. However, 5.7 mmol of serine were used instead of glycine.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.09%.

Example 4 (according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 1. However, 5.7 mmol of valine were used instead of glycine.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.09%.

Comparative example 1 (not according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 1. However, 5.7 mmol of urea was used instead of the glycine.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.13%.

Comparative example 2 (not according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 1. However, no glycine was added.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.15%.

Example 5 (according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 1. However, 100 g of a commercially available phenol-furan cold resin from the company Hüttenes-Albertus with the name Kaltharz 7864 (furfuryl alcohol: 40%, free phenol: 4% Water content: 2%, free formaldehyde content: 0.125% (corresponds to 4.2 mmol); available from Hüttenes-Albertus Chemische Werke GmbH), used instead of the phenol-furan cold resin with the designation XA20 used in Example 1. However, 4.2 mmol of glycine were used.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.04%.

The values determined are summarized in Table 1.

The (test) moldings according to the invention produced from the molding material mixture according to the invention show improved flexural strength after four hours compared with the (test) moldings produced according to Comparative Examples 3 and 4, without the setting behavior being negatively affected. In addition, the content is free Formaldehyde in the binder system according to the invention is lower than the content of free formaldehyde in the binder systems according to Comparative Examples 3 and 4.

Example 6 (according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 5. However, 4.2 mmol of alanine were used instead of glycine.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.05%.

Example 7 (according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 5. However, 4.2 mmol of serine were used instead of glycine.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.06%.

Example 8 (according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 5. However, 4.2 mmol of valine were used instead of glycine.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.05%.

Example 9 (according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 5. However, 4.2 mmol of glutamine were used instead of glycine.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.03%.

Comparative example 3 (not according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 5. However, 4.2 mmol of urea were used instead of the glycine.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.12%.

Comparative example 4 (not according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 5. However, no glycine was added.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.17%.

Example 10 (according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 1. However, 100 g of a commercially available phenol-furan cold resin from the Hüttenes-Albertus company with the designation Kaltharz 8117 (furfuryl alcohol: 50%, free phenol: 3 - 4%, water content: 2%, free formaldehyde content: 0.120% (corresponds to 4 mmol); available from Hüttenes-Albertus Chemische Werke GmbH) instead of the phenol-furan cold resin with the designation XA20 used in Example 1. However, 4.0 mmol of glycine were used.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.05%.

The values determined are summarized in Table 1.

The (test) moldings according to the invention produced from the molding material mixture according to the invention show in comparison to those produced according to Comparative Examples 5 and 6 (Test) moldings show improved flexural strength after 24 hours without the setting behavior being adversely affected. In addition, the content of free formaldehyde in the binder system according to the invention is lower than the content of free formaldehyde in the binder systems according to Comparative Examples 6 and 5.

Example 11 (according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 10. However, 4.0 mmol of alanine were used instead of glycine.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.05%.

Example 12 (according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 10. However, 4.0 mmol of serine were used instead of glycine.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.08%.

Example 13 (according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 10. However, 4.0 mmol of valine were used instead of glycine.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.07%.

Example 14 (according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 10. However, 4.0 mmol of glutamine were used instead of glycine.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.03%.

Comparative example 5 (not according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 10. However, 4.0 mmol of urea were used instead of the glycine.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.05%.

Comparative example 6 (not according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 10. However, no glycine was added.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.15%.

Example 15 (according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 1. However, 100 g of a commercially available phenol-furan cold resin from Hüttenes-Albertus with the name Kaltharz 8500 (furfuryl alcohol: 57%, free phenol: 1, 1 - 1.8%, water content: 8 - 10%, free formaldehyde content: 0.25% (corresponds to 8.3 mmol); available from Hüttenes-Albertus Chemische Werke GmbH) instead of the phenol-furan cold resin used in Example 1 with the Designation XA20 used. However, 8.3 mmol of glycine were used.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.04%.

The values determined are summarized in Table 1.

The (test) moldings according to the invention produced from the molding material mixture according to the invention show in comparison to those produced according to Comparative Examples 7 and 8 (Test) moldings show improved flexural strength after 24 hours without the setting behavior being adversely affected. In addition, the content of free formaldehyde in the binder system according to the invention is lower than the content of free formaldehyde in the binder systems according to Comparative Examples 7 and 8.

Example 16 (according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 15. However, 8.3 mmol of alanine were used instead of glycine.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.04%.

Example 17 (according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 15. However, 8.3 mmol of serine were used instead of glycine.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.05%.

Example 18 (according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 15. However, 8.3 mmol of valine were used instead of glycine.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.07%.

Example 19 (according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 15. However, 8.3 mmol of glutamine were used instead of glycine.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.06%.

Comparative example 7 (not according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 15. However, 8.3 mmol of urea were used instead of the glycine.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.19%.

Comparative example 8 (not according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 15. However, no glycine was added.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.27%.

Example 20 (according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 1. However, 100 g of a commercially available furan cold resin from the company Hüttenes-Albertus with the name Kaltharz TDE 20 (furfuryl alcohol: 70%, water content: 5 - 7% , Free formaldehyde content: 0.23% (corresponds to 7.7 mmol); available from Hüttenes-Albertus Chemische Werke GmbH) instead of the phenol-furan cold resin with the designation XA20 used in Example 1. However, 7.7 mmol of glycine were used.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.09%.

The values determined are summarized in Table 1.

The (test) moldings according to the invention produced from the molding material mixture according to the invention show in comparison with those produced according to Comparative Example 9 (Test) moldings show improved flexural strength after 24 hours without the setting behavior being adversely affected. In addition, the content of free formaldehyde in the binder system according to the invention is lower than the content of free formaldehyde in the binder systems according to Comparative Example 9.

Example 21 (according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 20. However, 7.7 mmol of alanine were used instead of glycine.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.08%.

Example 22 (according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 20. However, 7.7 mmol of serine were used instead of glycine.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.09%.

Example 23 (according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 20. However, 7.7 mmol of valine were used instead of glycine.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.07%.

Comparative example 9 (not according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 20. However, no glycine was added.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.23%.

Example 24 (according to the invention): Production of a binder system:

For 100 g of a commercially available phenol furan warm box resin from Hüttenes-Albertus with the designation "Furesan 7682" (furfuryl alcohol: 57%, free phenol: 1.0-1.6%, water content: 8-10%, free Formaldehyde content: 0.25% (corresponds to 8.3 mmol); available from Hüttenes-Albertus Chemische Werke GmbH), 0.62 g of glycine (8.3 mmol) were added at a temperature of 40 ° C. and the mixture was stirred for 60 minutes . After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.07%.

Production of a molding material mixture:

At room temperature (18-22 ° C) and a rel. Air temperature (40-55%) are placed in a laboratory mixer (BOSCH) 100 GT quartz sand H32, mixed with 0.3% hardener (Furedur 2) and mixed for 15 seconds. The sand / hardener mixture is then provided with 1.5 parts by weight of resin and mixed for a further 150 seconds. The temperature of the molding material mixture produced is 18-22 ° C.

Production of (test) moldings:

The molding material mixture was then introduced by hand into a test bar mold, compacted with a hand plate and cured at 220.degree. Cuboid test bars with the dimensions 220 mm x 22.36 mm x 22.36 mm, so-called Georg Fischer test bars, were produced as test specimens.

Various test moldings were produced and these were cured at 220 ° C. for 15, 30, 60 or 120 seconds.

The hot flexural strength (flexural strength directly after removal of the hot (test) shaped body) and the cold flexural strength (flexural strength of the cooled (test) shaped body after 24 hours) of the produced (test) shaped bodies were determined according to the determination method described in Example 1.

The results are summarized in Table 2.

The cold flexural strength of the (test) molded body produced is higher than in Comparative Example 11, in which no amino acid was added. The cold bending strength is particularly high for the samples with a short baking time (15 and 30 seconds). The hot bending strengths are not negatively affected.

These results are particularly surprising, since with phenol-furan warm box resins it was previously assumed that high flexural strengths (especially with short baking times) can only be achieved with a high content of free formaldehyde.

Example 25 (according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 24. However, 8.3 mmol of alanine were used instead of glycine.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of less than 0.08%.

The results are summarized in Table 2.

The cold flexural strength of the (test) molded body produced is higher than in Comparative Example 11, in which no amino acid was added. The cold bending strength is particularly high for the samples with a short baking time (15 and 30 seconds). The hot bending strengths are not negatively affected.

These results are particularly surprising, since with phenol-furan warm box resins it was previously assumed that high flexural strengths (especially with short baking times) can only be achieved with a high content of free formaldehyde.

Example 26 (according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 24. However, 8.3 mmol of glutamine were used instead of glycine.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of less than 0.08%.

The results are summarized in Table 2.

The cold flexural strength of the (test) molded body produced is higher than in Comparative Example 11, in which no amino acid was added. The cold bending strength is particularly high for the samples with a short baking time (15 and 30 seconds). The hot bending strengths are not negatively affected.

These results are particularly surprising, since with phenol-furan warm box resins it was previously assumed that high flexural strengths (especially with short baking times) can only be achieved with a high content of free formaldehyde.

Example 27 (according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 24. However, 8.3 mmol of serine were used instead of glycine.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of less than 0.08%.

Comparative example 10 (not according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 24. However, 8.3 mmol of urea was used instead of the glycine.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.07%.

Comparative example 11 (not according to the invention):

The binder system, the molding material mixture and the (test) moldings were produced analogously to Example 24. However, no glycine was added.

After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.18%.

Results:

Table 1: Comparison of the processing time (WT) and curing time (ST) and the flexural strengths of the (test) molded bodies produced in Examples 1 to 23 and Comparative Examples 1 to 9. Flexural strength after xx hours in [N / cm ² ] example Additive WT [min] ST [min] 1h 2h 4h 24 hours example 1 Glycine 7th 11 250 300 380 460 Example 2 Alanine 9 12th 220 300 360 430 Example 3 Serine 6th 9 210 270 370 430 Example 4 Valine 7th 10 230 300 370 440 Comparative example 1 urea 17th 27 55 165 185 200 Comparative example 2 No additive 9 12th 260 310 350 390 Example 5 Glycine 14th 20th 140 240 360 380 Example 6 Alanine 13th 20th 110 210 300 370 Example 7 Serine 11 18th 170 250 320 380 Example 8 Valine 14th 22nd 130 220 350 360 Example 9 Glutamine 14th 19th 80 200 330 350 Comparative example 3 urea 20th 32 60 140 230 290 Comparative example 4 No additive 12th 17th 150 240 290 340 Example 10 Glycine 13th 19th 170 310 370 390 Example 11 Alanine 11 17th 170 300 360 390 Example 12 Serine 10 17th 190 310 370 380 Example 13 Valine 9 16 220 330 360 400 Example 14 Glutamine 11 16 160 390 360 390 Comparative example 5 urea 18th 28 45 175 205 256 Comparative example 6 No additive 11 18th 130 240 340 350 Example 15 Glycine 7th 10 210 320 400 480 Example 16 Alanine 9 13th 180 310 390 450 Example 17 Serine 6th 9 180 310 390 430 Example 18 Valine 6th 10 200 320 400 440 Example 19 Glutamine 6th 9 190 310 360 450 Comparative example 7 urea 9 14th 125 295 340 370 Comparative example 8 No additive 5 9 230 280 350 400 Example 20 Glycine 15th 19th 160 260 370 440 Example 21 Alanine 14th 18th 140 210 360 440 Example 22 Serine 12th 18th 170 220 400 430 Example 23 Valine 12th 18th 120 250 360 420 Comparative example 9 No additive 12th 18th 120 250 340 400 Table 2: Comparison of the hot flexural strengths and cold flexural strengths of the (test) molded bodies produced in Examples 24 to 26 and in Comparative Example 11. Hot bending strengths in [N / cm ² ] - tested immediately after production after ... seconds of baking time at 220 ° C Cold bending strengths [N / cm ² ] - tested after the kernels have cooled down after ... seconds of baking time at 220 ° C 15 " 30 " 60 " 120 " 15 " 30 " 60 " 120 " Comparative Example 11 210 225 235 220 680 660 600 530 Example 24 215 220 240 230 740 710 630 580 Example 25 230 240 280 220 770 760 610 570 Example 26 200 220 270 220 780 740 610 550

Claims (14)

1. Mold material mixture for producing moldings for the foundry industry, preferably for producing foundry molds, cores or feeders for the foundry industry, which comprises

   A) one or more pourable, refractory fillers,

   B) a binder system comprising

   i) formaldehyde, a formaldehyde donor and/or precondensates of formaldehyde, wherein the binder additionally comprises furan derivatives and/or furfuryl alcohol or precondensates of furan derivatives and/or furfuryl alcohol,
   and

   ii) an amino acid selected from the group consisting of glycine, glutamine, alanine, valine and serine.
2. Mold material mixture according to Claim 1, wherein the amino acid is glycine.
3. Mold material mixture according to any of the preceding claims, wherein the one, at least one of the several or all pourable, refractory fillers are selected from the group consisting of silica sand, fused silica sand, olivine sand, chrome-magnesite granules, aluminum silicates, in particular J-sand, heavy minerals, in particular chromite, zircon sand and R-sand, industrial ceramics, in particular chamotte, M-sand, bauxite sand and silicon carbide, feldspar-containing sands, andalusite sands, hollow α-alumina spheres, spheres composed of fly ashes, rice hull ashes, expanded glasses, foamed glasses, expanded perlites, core-shell particles, fly ashes.
4. Mold material mixture according to any of the preceding claims, wherein the one, at least one of the several or all pourable, refractory fillers have an average particle diameter d50 in the range from 0.001 to 5 mm, preferably in the range from 0.01 to 3 mm, particularly preferably in the range from 0.02 to 2.0 mm and wherein the average particle diameter d50 is determined in accordance with DIN 66165-2, F and DIN ISO 3310-1.
5. Mold material mixture according to any of the preceding claims, wherein the ratio of the total mass of pourable, refractory fillers to the total mass of other constituents of the mold material mixture is in the range from 100:5 to 100:0.1, preferably from 100:3 to 100:0.4, particularly preferably from 100:2 to 100:0.6.
6. Mold material mixture according to any of the preceding claims, wherein the binder system additionally comprises:

   a) phenols, in particular phenol, o-cresol, p-cresol, 3,5-xylenol or resorcinol, or precondensates of phenols, in particular resols,
   and/or

   c) urea or urea derivatives or precondensates of urea or urea derivatives.
7. Mold material mixture according to any of the preceding claims, wherein the binder system is curable to give a

   i) phenol/furfuryl alcohol/formaldehyde resin,

   ii) furfuryl alcohol/formaldehyde resin,

   iii) urea/furfuryl alcohol/formaldehyde resin
   or

   iv) urea/furfuryl alcohol/phenol/formaldehyde resin.
8. Mold material mixture according to any of the preceding claims, wherein the proportion of all amino acids in the mold material mixture is from 0.005 to 2% by weight, preferably from 0.01 to 1% by weight, particularly preferably from 0.03 to 0.5% by weight, based on the solids content of the total mold material mixture.
9. Mold material mixture according to any of the preceding claims, wherein the molar ratio of all amino acids to available formaldehyde is from 4:1 to 1:0.5, preferably from 3:1 to 1:0.9, particularly preferably from 2.5:1 to 1:1.
10. Molding for the foundry industry produced using a mold material mixture as defined in any of Claims 1 to 9.
11. Use of at least one amino acid selected from the group consisting of glycine, glutamine, alanine, valine and serine in a mold material mixture for the foundry industry, wherein the mold material mixture contains, in addition to the amino acid, a binder system, comprising formaldehyde, a formaldehyde donor and/or precondensates of formaldehyde, wherein the binder additionally comprises furan derivatives and/or furfuryl alcohol or precondensates of furan derivatives and/or furfuryl alcohol.
12. Process for producing a mold material mixture according to any of Claims 1 to 9, which comprises the following steps:

    a) production or provision of one or more pourable, refractory fillers,

    b) production or provision of a binder system comprising

    i) formaldehyde, a formaldehyde donor and/or precondensates of formaldehyde, wherein the binder additionally comprises furan derivatives and/or furfuryl alcohol or precondensates of furan derivatives and/or furfuryl alcohol,
    and

    ii) an amino acid selected from the group consisting of glycine, glutamine, alanine, valine and serine,

    and

    c) mixing of all components.
13. Process for producing a molding for the foundry industry, which comprises the following steps:

    i) production or provision of a mold material mixture according to any of Claims 1 to 9,

    ii) shaping of the mold material mixture to give an uncured molding
    and

    iii) curing the uncured molding or allowing the latter to cure, so that a molding for the foundry industry results.
14. Kit for producing a mold material mixture according to any of Claims 1 to 9 and/or for producing a molding according to Claim 10, which comprises

    I) a binder system as defined in any of Claims 1 to 9,
    and

    II) a hardener, preferably an organic or inorganic acid, particularly preferably a sulfonic acid (in particular para-toluenesulfonic acid), phosphoric acid, carboxylic acid, methanesulfonic acid and/or sulfuric acid or mixtures thereof
    and

    III) optionally one or more pourable, refractory fillers as defined in any of Claims 1 and 3 to 5.