Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
  • B22C1/16—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents
  • B22C1/20—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of organic agents
  • B22C1/22—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of organic agents of resins or rosins
  • B22C1/2233—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of organic agents of resins or rosins obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • B22C1/224—Furan polymers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
  • B22C1/16—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents
  • B22C1/20—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of organic agents
  • B22C1/22—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of organic agents of resins or rosins
  • B22C1/2233—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of organic agents of resins or rosins obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • B22C1/2246—Condensation polymers of aldehydes and ketones
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
  • B22C1/16—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents
  • B22C1/20—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of organic agents
  • B22C1/22—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of organic agents of resins or rosins
  • B22C1/2233—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of organic agents of resins or rosins obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • B22C1/2246—Condensation polymers of aldehydes and ketones
  • B22C1/2253—Condensation polymers of aldehydes and ketones with phenols
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C9/00—Moulds or cores; Moulding processes
  • B22C9/02—Sand moulds or like moulds for shaped castings

Definitions

• 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.
• molten materials, ferrous metals or non-ferrous metals are converted into shaped objects with certain workpiece properties.
• 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.
• 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.
• 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.
• 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.
• 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.
• the refractory mold base material e.g. sand
• a catalyst hardener
• 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.
• 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.
• the refractory molding base material e.g. sand
• the hardener can first be mixed with the binder and then the hardener added.
• 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.
• Furfuryl alcohol can react with itself under acid catalysis and form a homopolymer.
• 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.
• 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.
• Molding mixtures based on formaldehyde usually have very good properties.
• 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.
• 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.
• 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.
• 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.
• the binder system 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.
• 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.
• 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.
• MAK maximum workplace concentration
• 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.
• urea 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.
• a binder 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.
• a binder 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.
• the molded bodies for the foundry industry are feeders, foundry molds or cores for the foundry industry.
• 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.
• 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.
• 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.
• molding material mixtures according to the invention are particularly preferred, the binder system being thermally curable.
• 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.
• 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.
• 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.
• a 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.
• 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.
• 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.
• 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.
• a latent hardener warm box
• a 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.
• 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.
• urea / furfuryl alcohol / phenol / formaldehyde resin-bound molding materials are produced during curing.
• 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.
• 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 .
• a latent hardener warm box
• a 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
• the amino acid is selected from the group consisting of glycine, glutamine, alanine, valine and serine.
• the amino acids glycine, glutamine, alanine, valine and serine in particular have good properties when used in molding material mixtures according to the invention.
• 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.
• the content of free formaldehyde in the molding material mixture and in the moldings produced from the molding material mixture can be reduced.
• the amino acids glycine is particularly preferred. Molding material mixtures according to the invention are preferred, the amino acid being an ⁇ -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.
• 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 .
• 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.
• 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.
• 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.
• 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.
• the uncured molded body is hardened or allowed to harden by heating.
• 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.
• Example 1 (according to the invention):
• 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.
• 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 (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.
• 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.
• 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.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.08%.
• 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.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.09%.
• 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.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.09%.
• 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.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.13%.
• the binder system, the molding material mixture and the (test) moldings were produced analogously to Example 1. However, no glycine was added.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.15%.
• the binder system, the molding material mixture and the (test) moldings were produced analogously to Example 1.
• 100 g of a commercially available phenol-furan cold resin from the company Wilsontenes-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 Wilsontenes-Albertus Chemische Werke GmbH), used instead of the phenol-furan cold resin with the designation XA20 used in Example 1.
• 4.2 mmol of glycine were used.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.04%.
• 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.
• 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.
• 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.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.05%.
• 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.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.06%.
• 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.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.05%.
• 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.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.03%.
• 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.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.12%.
• the binder system, the molding material mixture and the (test) moldings were produced analogously to Example 5. However, no glycine was added.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.17%.
• the binder system, the molding material mixture and the (test) moldings were produced analogously to Example 1.
• 4.0 mmol of glycine were used.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.05%.
• 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.
• 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.
• 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.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.05%.
• 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.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.08%.
• 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.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.07%.
• 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.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.03%.
• 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.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.05%.
• the binder system, the molding material mixture and the (test) moldings were produced analogously to Example 10. However, no glycine was added.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.15%.
• the binder system, the molding material mixture and the (test) moldings were produced analogously to Example 1.
• 100 g of a commercially available phenol-furan cold resin from Wilsontenes-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 Wilsontenes-Albertus Chemische Werke GmbH) instead of the phenol-furan cold resin used in Example 1 with the Designation XA20 used.
• 8.3 mmol of glycine were used.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.04%.
• 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.
• 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.
• 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.
• the binder system 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.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.05%.
• 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.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.07%.
• 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.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.06%.
• 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.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.19%.
• the binder system, the molding material mixture and the (test) moldings were produced analogously to Example 15. However, no glycine was added.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.27%.
• the binder system, the molding material mixture and the (test) moldings were produced analogously to Example 1.
• 7.7 mmol of glycine were used.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.09%.
• 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.
• 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.
• 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.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.08%.
• 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.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.09%.
• 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.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.07%.
• the binder system, the molding material mixture and the (test) moldings were produced analogously to Example 20. However, no glycine was added.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.23%.
• 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.
• 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 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.
• 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.
• the binder system 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 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.
• 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.
• the binder system 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 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.
• 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.
• the binder system 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 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.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.07%.
• the binder system, the molding material mixture and the (test) moldings were produced analogously to Example 24. However, no glycine was added.
• the binder system After the binder system had cooled to room temperature (18-22 ° C.), the binder system had a free formaldehyde content of 0.18%.
• 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

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