WO2022008001A1 - Matière à mouler pour fabriquer des noyaux et procédé pour durcir la matière à mouler - Google Patents

Matière à mouler pour fabriquer des noyaux et procédé pour durcir la matière à mouler Download PDF

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Publication number
WO2022008001A1
WO2022008001A1 PCT/DE2021/100587 DE2021100587W WO2022008001A1 WO 2022008001 A1 WO2022008001 A1 WO 2022008001A1 DE 2021100587 W DE2021100587 W DE 2021100587W WO 2022008001 A1 WO2022008001 A1 WO 2022008001A1
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WO
WIPO (PCT)
Prior art keywords
molding material
component
binder
material according
resin component
Prior art date
Application number
PCT/DE2021/100587
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German (de)
English (en)
Inventor
Daniel HOLSTEIN
Sandra ESCHRICH
Thomas GALLERT
Tina HERTEL
Robin GOLDACKER
Original Assignee
Bindur Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Bindur Gmbh filed Critical Bindur Gmbh
Priority to EP21762591.2A priority Critical patent/EP4178742A1/fr
Publication of WO2022008001A1 publication Critical patent/WO2022008001A1/fr

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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
    • B22C1/2273—Polyurethanes; Polyisocyanates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/10—Cores; Manufacture or installation of cores
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/12—Treating moulds or cores, e.g. drying, hardening
    • B22C9/123—Gas-hardening
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/30—Low-molecular-weight compounds
    • C08G18/302—Water
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/30—Low-molecular-weight compounds
    • C08G18/32—Polyhydroxy compounds; Polyamines; Hydroxyamines
    • C08G18/3203—Polyhydroxy compounds
    • C08G18/3206—Polyhydroxy compounds aliphatic
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40—High-molecular-weight compounds
    • C08G18/4009—Two or more macromolecular compounds not provided for in one single group of groups C08G18/42 - C08G18/64
    • C08G18/4018—Mixtures of compounds of group C08G18/42 with compounds of group C08G18/48
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40—High-molecular-weight compounds
    • C08G18/42—Polycondensates having carboxylic or carbonic ester groups in the main chain
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40—High-molecular-weight compounds
    • C08G18/42—Polycondensates having carboxylic or carbonic ester groups in the main chain
    • C08G18/4202—Two or more polyesters of different physical or chemical nature
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40—High-molecular-weight compounds
    • C08G18/42—Polycondensates having carboxylic or carbonic ester groups in the main chain
    • C08G18/44—Polycarbonates
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40—High-molecular-weight compounds
    • C08G18/48—Polyethers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40—High-molecular-weight compounds
    • C08G18/48—Polyethers
    • C08G18/4804—Two or more polyethers of different physical or chemical nature
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40—High-molecular-weight compounds
    • C08G18/48—Polyethers
    • C08G18/4833—Polyethers containing oxyethylene units
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/65—Low-molecular-weight compounds having active hydrogen with high-molecular-weight compounds having active hydrogen
    • C08G18/66—Compounds of groups C08G18/42, C08G18/48, or C08G18/52
    • C08G18/6603—Compounds of groups C08G18/42, C08G18/48, or C08G18/52 with compounds of group C08G18/32 or polyamines of C08G18/38
    • C08G18/6607—Compounds of groups C08G18/42, C08G18/48, or C08G18/52 with compounds of group C08G18/32 or polyamines of C08G18/38 with compounds of group C08G18/3203
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/65—Low-molecular-weight compounds having active hydrogen with high-molecular-weight compounds having active hydrogen
    • C08G18/66—Compounds of groups C08G18/42, C08G18/48, or C08G18/52
    • C08G18/6603—Compounds of groups C08G18/42, C08G18/48, or C08G18/52 with compounds of group C08G18/32 or polyamines of C08G18/38
    • C08G18/6607—Compounds of groups C08G18/42, C08G18/48, or C08G18/52 with compounds of group C08G18/32 or polyamines of C08G18/38 with compounds of group C08G18/3203
    • C08G18/6611—Compounds of groups C08G18/42, C08G18/48, or C08G18/52 with compounds of group C08G18/32 or polyamines of C08G18/38 with compounds of group C08G18/3203 having at least three hydroxy groups
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
    • C08G18/72—Polyisocyanates or polyisothiocyanates
    • C08G18/74—Polyisocyanates or polyisothiocyanates cyclic
    • C08G18/76—Polyisocyanates or polyisothiocyanates cyclic aromatic
    • C08G18/7657—Polyisocyanates or polyisothiocyanates cyclic aromatic containing two or more aromatic rings
    • C08G18/7664—Polyisocyanates or polyisothiocyanates cyclic aromatic containing two or more aromatic rings containing alkylene polyphenyl groups

Definitions

  • the invention relates to a molding material for producing cores in the cold box process.
  • This molding material includes natural and/or ceramic sand and a two-component polyurethane binding agent that is free of phenol and phenol derivatives.
  • the invention relates to a method for curing this molding material.
  • the molding material can be cured in the cold box process by gassing with tertiary amines in short cycle times.
  • the possibility of replacing phenolic urethane resin binders that have been used up to now means that considerable emissions advantages are achieved in the case of binder burn-off caused by casting.
  • cold-box processes Gassing-hardening processes for core production in non-heated core boxes are generally referred to as cold-box processes.
  • the PU cold box process phenolic urethane cold box or polyurethane cold box
  • the abbreviation “cold box process” is also used within the scope of this disclosure document when talking about the gassing-hardening PU cold box process.
  • the cores are generally made with a special core shooter.
  • the molding material which consists of a mixture of basic molding material, resin and hardener, is introduced into an unheated core box and compressed using compressed air from the machine's shooting head.
  • the molding material is hardened by passing an amine-carrier gas mixture through the core box.
  • the carrier gas is generally Air, but can also be an inert gas such as nitrogen or argon. Then excess amine is flushed out of the core box with compressed air.
  • the molding material core obtained in this way has a sufficiently high initial strength to be removed from the core box without distortion.
  • the core is post-cured until the molding material has reached its so-called ultimate strength.
  • the hardening of the molding material catalyzed by tertiary amines enables short core production cycle times, so that the process is primarily used for large series and automated processes in foundries.
  • Cold box binders are two-component binders consisting of a polyol-containing resin component and an isocyanate-containing hardener component, which react to form the polyurethane when the molding material hardens.
  • Cold box binders currently on the market generally consist, as described in US Pat. No. 3,409,579 A, of phenol-formaldehyde resins in a solvent as the polyol component and a hardener component of an aromatic polyisocyanate in a suitable solvent.
  • the solvents used are usually volatile aromatic hydrocarbons.
  • Volatile, tertiary amines such as triethylamine in gaseous form are used to quickly harden the molding material in the core box.
  • Phenol-formaldehyde resins are hydroxy-functional polyols formed by the condensation of mono- or polyhydric phenols with aldehydes, especially formaldehyde. The reaction proceeds with acidic catalysis in such a way that so-called novolaks are formed, and with base catalysis to form resol resins.
  • the core box is heated to 40 to 80 °C, which results in faster binder crosslinking on the outside of the core. Strength and moisture resistance of the cores are thus compared to the regular Cold box process significantly increased.
  • Volatile, tertiary amines such as trimethylamine, triethylamine, dimethylethylamine or dimethylpropylamine are used as amines for catalysis in the cold box process.
  • EP 2 106310 B1 describes mixtures of at least two tertiary amines, mostly as a combination of higher and lower boiling amines, as being advantageous for handling and curing the molding material. The amount of amine required is reduced compared to using the higher boiling point amine, while the odor load is lower than when the low boiling point amine alone is used.
  • Phenolic resin-based cold-box binders contain various additives and additives in addition to the components that are essential for curing: phenolic resin, polyisocyanate and catalyst. Acidic additives are added to the components to ensure that the molding material has a long processing life.
  • phosphorus halides such as phosphoryl chloride are used for this purpose.
  • chlorosilanes to increase the lifetime of the sand is described in DE 3405 180 A1.
  • the disadvantage here is that chlorine-containing compounds can decompose with the release of hydrochloric acid. This is hazardous to health and also corrosively attacks the surrounding metal parts.
  • a variant that is less harmful to health is described in DE 102012201 971 A1.
  • Mixtures of methanesulfonic acid, phosphoric acid esters and silanes are added to the isocyanate-containing component, which allows the sand to be extended and its storage stability to be increased.
  • the open time of cold-box binders based on phenolic resin and isocyanate can be extended to up to 4 hours by adding phosphorus-containing acids and derivatives thereof.
  • adhesion promoters such as alkoxysilanes are used to improve the adhesive effect of the binder in the refractory filler and the storage stability of the core obtained.
  • DE 2906052 A describes a cold box binder in which the resin component comprises a phenolic resin which is diluted with a mixture of aromatic hydrocarbon and a phosphate and/or carbonate ester.
  • This solvent variation achieves an increased curing speed and increased heat resistance of the cores.
  • the aromatic solvents which are hazardous to health, could not be dispensed with completely.
  • DE 19542752 A1 discloses the use of rapeseed methyl ester or dibasic ester as a thinner for the resin and/or hardener component of a cold box binder, as a result of which aromatic hydrocarbons that are harmful to health can be completely replaced during processing.
  • rapeseed methyl ester are a good Separation effect between mold and core as well as low outgassing during casting are described.
  • alkyl silicates are used as solvents for phenolic resin and isocyanates, in particular tetraethyl orthosilicate. This avoids the emission load that comes from the aromatic solvents otherwise used, without any disadvantages for the other binder properties. Casting properties are even improved as the thermal resistance of cores and molds is very high and lower gas pressure development is observed.
  • alkyl silicates also have disadvantages. They contaminate the acidic solution in the downstream amine scrubber through gel formation and can release finely divided white silicate particles during processing of the molding material, which are released into the air as suspended matter.
  • tetraethyl silicate has an intensely pungent odor and is classified as an eye and respiratory tract irritant and harmful if inhaled.
  • WO 2011008362 A1 describes a cold box system in which the resin consists of a phenolic resin, polyetherpolyol, polyesterpolyol, an aminopolyol or mixtures thereof, phenolic resins being preferred.
  • Solvents are necessarily used in resin and/or hardener cycloalkanes, which are said to bring about positive properties such as improved casting quality. Only a binder containing phenolic resin is disclosed in the examples.
  • the other polyol types are listed in the descriptive part, but their actual suitability is not proven with examples.
  • the phenolic resins themselves or their production-related unavoidable monomer content of the toxic CMR substances formaldehyde and phenol, which can be carcinogenic, mutagenic or toxic to reproduction, pose a significant burden on the environment and the health of the processor in all steps of molding, through casting to landfilling of the molding material.
  • a number of publications list efforts to avoid their release.
  • the phenol content is reduced by using modified phenolic resins.
  • free hydroxy functions of the phenolic resin units are linked or substituted by esters of orthosilicic acid and its polymers.
  • the advantages are, among other things, reduced odor nuisance, fewer pollutant emissions and increased thermal resistance.
  • some phenol is replaced by cresols (methylphenol), which are not CMR substances but are still toxic.
  • a further disadvantage of phenolic resin-based cold box systems is a high tendency to casting defects due to so-called veining or hot cracking in gray and steel castings. These casting defects can be partially avoided by organic (wood flour) or inorganic mold material additives (iron oxide). However, the additives themselves cause undesired effects. The emission load during casting is significantly increased by organic additives and gas-induced casting defects therefore occur more frequently.
  • the inorganic additives on the other hand, accumulate in the regenerated sand and thus lower the sintering point of the molding material, which is undesirable with regard to the casting and can also lead to casting defects.
  • part of the phenolic resin is replaced with aliphatic or aromatic polyether alcohols in order to reduce the tendency towards casting defects when using cores produced in the cold box process.
  • phenol and benzyl alcohol derivatives with a low molecular weight are also necessary.
  • the resin component used continues to consist largely of phenol-based substances.
  • WO 001990005155 A1 describes a polyurethane binder based on phenol-formaldehyde resin and polyisocyanate which, by adding 2.0 to 8.0% polyester polyol based on the weight of the phenolic resin component, has improved decomposition properties of a molding material produced therewith. It is therefore particularly suitable for casting with low-melting metals such as aluminium. Furthermore, a flattening of the molding material by gaseous amines according to the cold box process is described.
  • cold box can also be used for other gas-curing processes, for example urea-formaldehyde or phenol-formaldehyde resins that are cured with sulfur dioxide.
  • DE 102005024334 A1 discloses a multi-component system consisting of epoxy resin, an unsaturated ethylene compound, a saturated fatty acid and radical initiators, which is cured with sulfur dioxide.
  • the epoxy resins used are mostly based on bisphenol A, which has been shown to damage fertility in humans and is therefore no longer allowed to be used in the manufacture of everyday objects.
  • cores that were produced using the SO 2 cold box process deform under thermal stress, which is an undesirable effect when the cores are oven-dried after so-called sizing.
  • Another gas-hardening molding material process is based on sodium silicate binders. These water glasses, which are often modified, can be hardened in the molding material by gassing with CO 2 in relatively short cycle times.
  • the water glass C0 2 process which was developed by Leo Petrzela in 1947, is considered to be the first gassing-hardening cold box process.
  • water glass-based binders are their silicate, non-organic structure. This means that no pollutants are emitted through VOC release or combustion during molding and casting.
  • silicate binders had to contend with massive disadvantages in the casting process. When subjected to thermal stress in the cast, they show a softening point that can lead to distortion of the cast part. In addition, they accumulate quickly in the recycled molding material and thus lead to an undesirable reduction in the sintering point in the recycled molding material.
  • the high pH value of used sands to be landfilled due to their strongly basic properties, leads to classification in unfavorable and cost-intensive landfill classes.
  • the low flowability of the molding materials restricts the ability to shoot, especially of filigree core elements, which also makes it difficult to handle thin-walled moldings due to the comparatively low strength, especially when removing the casting molds.
  • the shelf life is limited in the case of increased humidity.
  • WO 2009056320 A1 describes surface-active surfactants, such as fatty acid sulfates, sulfonates or phosphates, which increase the flowability of the molding material.
  • Organic substances are often used to promote the decomposition properties of silicate mold materials during casting. These burn during pouring. The resulting pores in the molding material structure are intended to improve the ability of the molding material to be cored out of the cast part.
  • Typical examples of such decomposition additives are residual products from the sugar industry, such as molasses or syrup, and from the cellulose processing industry, in particular the tall oil described in DD 13105 A5. However, these lead to increased emissions during casting.
  • Inorganic additives can also be used to positively influence the decomposition behavior of the molding material. For example, DE 102013 111 626 A1 discloses oxidic boron compounds and DE 102017 107531 A1 describes particulate phyllosilicates, which also improve coreability after casting.
  • WO 002009004086 A1 discloses what is known as an alternative cold box process which contains a glycerol ester, a saccharide, a polyol, a crude oil or mixtures of these compounds as reactive polyol components in the binder. This avoids emissions of harmful substances such as phenol, formaldehyde and aromatic solvents. Curing takes place with water or a water-amine mixture at temperatures of preferably more than 80° C. in order to reduce exposure to the amine gas at the workplace. Water is obviously necessary as a reactant for curing, which is why one cannot speak of a cold box system in the classic sense.
  • WO 002009065015 A1 describes a bio-based binder system in which saccharides obtained from corn syrup and molasses react with isocyanates in order to bind a basic mold material to foundry molding compounds in a self-curing process.
  • aliphatic monoalcohols and polyols such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, hexane-1,6-diol, 2-methyl-1,3-propanediol, glycerol, mannitol, sorbitol , Diethylene glycol, triethylene glycol, polyethylene glycols, polypropylene glycols and butylene, dibutylene and polybutylene glycols are mentioned as further hydroxy-functional components.
  • the shelf life of cold box binders is extended by using a polyurethane-based binder whose resin component was obtained by condensation of aliphatic ketones with formaldehyde.
  • This binder does not use phenols as hydroxy-functional resin components, but the use of aromatic solvents is described to reduce the viscosity of the resin to humiliate.
  • WO 002000040351 A1 describes a polyurethane binder which is made up of a polyol component consisting of a polyether polyol, glycol and aromatic polyester polyol with 5 to 35% based on the total mass of the polyol component, an organic polyisocyanate component and a liquid amine catalyst and is contained in the self-curing cold resin procedure can be applied.
  • a polyol component consisting of a polyether polyol, glycol and aromatic polyester polyol with 5 to 35% based on the total mass of the polyol component, an organic polyisocyanate component and a liquid amine catalyst and is contained in the self-curing cold resin procedure can be applied.
  • phenolic resins such as benzyl ether resins can be present in the polyol component at up to 15% by weight.
  • the molding materials used to date in foundries for the production of cores in the cold box process have in common that their binders are based on phenolic resins and polyisocyanates. These enable the molding material to be cured by gassing with volatile amines in very short cycle times. Depending on the amount of molding material to be hardened, cycle times of 30 to 90 seconds are common.
  • the use of phenolic resins entails considerable emissions in the production of mold material and in particular in the pyrolytic decomposition of the binder during casting. In the process, a significant proportion of the monomers from which the phenolic resins are made are released. In particular, substances that are hazardous to health and have a workplace limit value, such as phenol and phenol derivatives, formaldehyde and BTEX compounds, are emitted.
  • aliphatic polyols can also be used on the resin side instead of the aromatic phenolic resins for self-curing molding material binders.
  • Polyether polyols in particular are used here, but they are not reactive enough to achieve the cycle times that are usual in the cold box process through amine gassing. The cycle times achieved with this are regularly several minutes.
  • the object on which the present invention is based is to develop a molding material that hardens with amine gas, in which the resin component of the binder is completely free of phenol and phenol derivatives and, in addition to rapid flattening and high molding material strength, also a low BTEX, phenol and emission of phenol derivatives when the molding material binder burns off as a result of casting.
  • the object of the invention is achieved with a molding material having the features of claim 1.
  • This molding material can be hardened by supplying amine gas and is suitable for the production of cores using the cold box process. Further developments are specified in the claims dependent on claim 1.
  • the molding material according to the invention comprises at least one two-component, phenol- and phenol-derivative-free binder based on polyurethane and one or more refractory pourable fillers.
  • other non-phenolic polyols are used instead of phenols and phenol derivatives, which have a similarly high reactivity as the Have phenolic resins.
  • the binder contains a resin component as a mixture of one or more branched aliphatic or aromatic polyester polyols built up from branched aliphatic or aromatic diol or triol starters with one or more side chains and substituted or unsubstituted aliphatic and/or aromatic di- and/or Tricarboxylic acids or their anhydrides, and/or one or more polycarbonate alcohols with equivalent weights of 250 to 4000 g/eq and hydroxy functionalities of 2 to 4 as hydrogen-active compounds with respect to isocyanates, the branched polyester polyol(s) and/or polycarbonate alcohols of the resin Component of the binder have a proportion in the range of 35 to 100 wt .-% of the resin component, and a hardener com component with one or more polyisocyanates.
  • the mixture can contain further compounds with hydroxyl and/or mercapto and/or amino and/or carbamide groups which are hydrogen-active in relation to isocyanates.
  • the resin component contains hydrogen-active individual compounds with regard to isocyanate, the resin component having an average functionality of 1.8 to 4.0 with regard to all of these hydrogen-active individual compounds, and optionally additives such as one or more diluents and optionally one or more liquid catalysts affecting the polymerization.
  • the hardener component comprises one or more isocyanates, which preferably have at least functionality 2, and can also contain one or more diluents as additives.
  • the number of specific functional groups in the relevant molecule is referred to here as the functionality of a compound. In the case of isocyanates, functionality refers to the number of NCO groups in a molecule.
  • the compounds that are hydrogen-active with respect to isocyanates such as the polyols, the sum of OH, NH and SH groups in a molecule is taken as the functionality designated.
  • the other individual compounds that are hydrogen-active with regard to isocyanates can be selected from one or more substance classes, such as polyester polyols, polycarbonate alcohols, polyether alcohols, polyether polyester alcohols, polythiols,
  • Aminopolyether alcohols alcohols with two or more functions, amines and carbamide compounds.
  • the hydrogen-active compounds mentioned advantageously have OH, SH and NH functionalities of 1.5 to 8 and equivalent weights of 9 to 2000 g/val, based in each case on the hydrogen-active individual compounds. Two or more of these compounds are preferably incorporated into the resin component.
  • the individual constituents of the resin component are chosen so that the resin component in relation to the totality of the isocyanate hydrogen-active individual compounds has an average functionality of 2.2 to 3.5.
  • the combination of two-functional compounds with higher-functional compounds has proven to be advantageous for optimum polymer crosslinking.
  • Polyester polyols composed of a branched aliphatic or aromatic diol and triol starter with one or more side chains which are not hydrogen-active with respect to isocyanates, and substituted or unsubstituted aliphatic and/or aromatic di- and/or tricarboxylic acids or their anhydrides.
  • the resin component of the molding material contains branched polyester polyols and/or polycarbonate alcohols, preferably in a proportion of 40 to 80% by weight. While polyester polyols based on linear diols or triols already result in a high reactivity of the binder when gassed with amine, it is possible with the described polyester polyols based on branched diols or triols to achieve molding material curing speeds that are comparable to those of phenolic resin-based binders in the molding material to come close.
  • the or at least some of the side chains of a branched polyester polyol of the molding material can be selected from the following substance classes: from aliphatics, aromatics, aldehydes, ketones, carboxylic acid esters, ethers, amines, alkyl halides, nitriles, nitrogen, oxygen and sulfur heterocycles and carboxamides.
  • Suitable starters for the branched polyester polyols described have the following structure: , where the radicals R n include the following chemical structures:
  • R 1 H, (CH 2 ) O-5 0H, OH, aliphatic, ether, aromatic, heterocycle,
  • R 2 aliphatic, ether, aromatic, heterocycle, carboxylic acid ester, carboxamide, haloalkane, amine, nitrile, ketone, aldehyde or combinations thereof,
  • R 3 H, (CH 2 ) O-5 OH, OH, aliphatic, ether, aromatic, heterocycle,
  • R 4 H, aliphatic, ether, aromatic, heterocycle, carboxylic acid ester,
  • divalent starters according to the described
  • Structural formula are with a C2 distance of the hydroxy functions 2-phenyl-1,2-propanediol, 1,2-propanediol, 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-heptanediol, 1 ,2-octanediol, 1,2-decanediol, 3-bromo-1,2-propanediol, 1,4-dibromo-
  • Polycarbonate alcohols are built up from carbonates such as dimethyl carbonate, ethylene carbonate or dipentyl carbonate and divalent crosslinkers, for example 1,3-propanediol, neopentyl glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol or trimethylolpropane (TMP).
  • Low-viscosity polycarbonate alcohols that are easy to process contain various types of crosslinkers.
  • carbon dioxide is polymerized with epoxides such as propylene oxide, the resulting polyols having a carbon dioxide content of up to 50%.
  • the proportion of the above-described branched polyester polyols and/or polycarbonate alcohols in the resin components is preferably from 35 to 100% by weight and particularly preferably from 40 to 80% by weight.
  • the branched polyester polyols and the polycarbonate alcohols show an advantageous resistance to hydrolysis compared to other polyol types, which leads to good storage stability of the foundry cores and good resistance to aqueous sizes.
  • branched polyester polyols and polycarbonate alcohols are particularly suitable as crosslinking polyols for the production of the resin component.
  • polystyrene resin polystyrene resin
  • Desmophen® VPLS from Covestro®
  • Oxyester® from Evonik®
  • Kuraray® polyol from Kuraray®
  • DuranolTM by Asahi Kasei®
  • Placcel® by Daicel®
  • Converge® Polyol by Saudi Aramco®
  • Durez®-Ter by Sumitomo Bakelite®
  • Eternacoll® by Ube®
  • Nippolan® by Tosoh® Oxymer® by Perstorp®
  • Polyol CA ® from Chanda Chemical® and Hoopol® from Synthesia®.
  • Durez®-Ter S1015-35, S1015-62, S1015-120, S1016-55, S1016-110, S1016-120, S1063-35, S1063-55, S1063-72, S1063-120, S1063-210, S1151- 22 S1157-40 S1160-35 EP092-30 S2000-55 S2000-120 S2000-250 S2001-120 S2005-55 S2006-55 S2006-120 S2006-250 Eternacoll® PH- 50, PH-100, PH-200, PH-300, Nippolan® 982R and Oxymer® M112, HD112, HD56, Polyol CA® 6010, 6020, 6040, 6050, 6410, 6420, 6440-N, Hoopol® F-601 , F-690, F-10201, F-10670, F-20013 and F-9690.
  • Unbranched aromatic or aliphatic polyester poles are also used. These are, for example, Hoopol® from Synthesia®, Boltorn® and Capa® from Perstorp®, Polyol CA® from Chanda Chemical®, Desmophen® from Covestro®, Diexter® and Isoexter® from Coim®, Domopol® from Helios®, Durez®- Ter from Sumitomo Bakelite®, Dynacoll® from Evonik®, Elapol® from Elachem®, K-POL® from King Industries®, Kuraray® Polyol from Kuraray®, Lupraphen® and Sovermol® from BASF®, Petopurol® from Petopur®, Placcel ® by Daicel®, Polios® by Purinova®, Polyol SP® by Caspian Chemical®, Rexin® by Sapici®, Stepanpol® by Stepan®, Terate® by Invista®, Terol® by Huntsman®, TRI-REZ
  • polyol compounds are two- to five-functional polyether alcohols.
  • Such polyols are, for example, Voranol® from Dow Chemical®, Desmophen® from Covestro®, Lupranol® from BASF®, Isoter® from Coim®, Puranol® from Jiahua®, Lipoxol® from Sasol®, polyglycol from Clariant® and polyols from Perstorp ®.
  • the Thioplast® types from Akzo Nobel® and the Thiocure® range from Bruno Bock have proven themselves as hydrogen-functional, sulphur-containing additives.
  • Polyetherdiamines such as Jeffamine® D-400 and D-230 from Huntsman® or compounds such as diglycolamine can be used as NH-functional compounds.
  • Diols such as ethylene glycol, 1,3-propanediol, 2-butyl-2-ethylpropanediol, 2-methyl-1,3-propanediol,
  • the binders are processed with or without additional catalytic support.
  • liquid or solid tertiary amine catalysts and/or metal-based catalysts or organometallic compounds which accelerate the polyurethane reaction are advantageously used as catalysts.
  • the following catalysts have a boiling point greater than 120 °C and are included as part of the resin component and/or added to the molding material as an individual component.
  • Organotin, organobismuth, organozinc, organopotassium and organoaluminum compounds and tertiary nitrogen-containing substances such as dimethylcyclohexylamine, N-substituted pyrrolidones, N-substituted imidazoles, diazabicyclooctane and triazine derivatives are suitable as catalysts.
  • Suitable metal-based catalysts are for example the Kosmos® and DABCO® types from Evonik®, TIB KAT® from TIB® Chemicals, K-Kat® products from King Industries®, the Borchi® Kat series from Borchers® and Tytane® by Borica.
  • a comprehensive selection of catalysts with tertiary nitrogen is offered by BASF with the Lupragen® series, Lanxess® with Addocat® types, Momentive with Naix® types, Evonik® with Tegoamin® and DABCO® types, and Huntsman® with the Jeffcat® range.
  • Particularly suitable isocyanates of the hardener component of the molding material according to the invention are oligomers or polymeric derivatives of the basic type of 2,4'- and 4,4'-diphenylmethane diisocyanate and/or oligomers or polymeric derivatives of the type of 2,4'- and 4, 4'-dicyclohexylmethane diisocyanates and/or oligomeric or polymeric derivatives of hexamethylene diisocyanate and/or isophorone diisocyanate and/or its derivatives, as well as the aromatic, aliphatic and cycloaliphatic isocyanates prepared in a prepolymer process and their oligomers and polymers.
  • Oligomeric and polymeric derivatives of isocyanates include carbodiimides, isocyanurates, biurets, uretdiones, and uretonimines. Preferably they have Isocyanates have at least a functionality of 2.0 and are liquid at room temperature.
  • isocyanate prepolymers can be used in the hardener component. These are produced by pre-crosslinking difunctional or polyfunctional polyols in a stoichiometric deficiency with suitable aliphatic and/or aromatic and/or cycloaliphatic isocyanates. These prepolymer components preferably contain a residual content of free isocyanate groups of 15 to 30%, particularly preferably 18 to 25%.
  • the isocyanate content of the hardener component in the molding material is advantageously chosen in relation to the hydrogen-active compounds of the resin component in such a way that free NCO groups of the hardener component and OH and/or NH and/or SH Groups of the resin component are present in a molar ratio of 0.8 to 1.2.
  • Suitable isocyanates for binders of a molding material according to the invention include Lupranat® types from the BASF® product range, Desmodur® types from Covestro®, Voranate® types and Isonate® types from Dow Chemical®, Vestanat® Types from Evonik®, the Suprasec® series from Huntsman®, TolonateTM types from Vencorex®, Polurene® types and Hydrorene® types from Sapici® or also Ongronat® types from Wanhua®.
  • the suitable isocyanates mentioned above include, in particular, Lupranat® M 70 R, Lupranat® MM 103, Lupranat® M 105, Lupranat® MIP, Lupranat® M 10 R, Lupranat® M 20 S, Desmodur® 44 V 70 L, Desmodur® 44 V 20 L, Desmodur® CD-S, Desmodur® DN, Desmodur® I, Desmodur® W/1 , Vestanat® IPDI, Vestanat® H12MDI, Vestanat® TMDI, Vestanat® HT 2500/LV, Suprasec® 2030, Suprasec® 2085 , Tolonate® HDB LV, Tolonate® HDT LV, Ongronat® 3800, Ongronat® CR-30-20, Ongronat® CR-30-40, Ongronat® CR-30-60, Voranate® M229 and Voranate® M600.
  • the binder components of the molding materials according to the invention are preferably through with the aim of good processability Thinner added.
  • diluents are, for example, fatty acid esters based on renewable raw materials, such as transesterification products from vegetable oils, especially their methyl, ethyl, propyl, isopropyl, butyl, isobutyl and ethylhexyl esters.
  • fatty acid esters from natural oils are rapeseed methyl esters, the palm and soya methyl esters from Cremer®, the Priolube® types from Croda®, the DUB® products from Stearinerie Dubois®, and the RADIA® esters from Oleon®.
  • Oxsoft® and Oxblue® esters from Oxea® dibasic esters from Du Pont®, Softenol® esters from Sasol®, the Jayflex® products from Exxon®, those with Freeflex ® dibenzoate esters from Caffaro® or plasticizers from BASF®, such as Flexamoll® DINCFI or Plastomoll®.
  • suitable cyclic and non-cyclic carbonates, such as propylene carbonate are the Jeffsol® variants of Fluntsman®.
  • organosilicates in particular alkyl silicates and alkyl silicate oligomers, are tetraethyl silicate, tetra-n-propyl silicate and mono-, di- and trialkyl silicates from Wacker®, Evonik® and Dow Corning®.
  • the Flarz component of the binder has 45 to 100% by weight, preferably 70 to 90% by weight, of hydrogen-active compounds and the Flarter component of the binder has 60 to 100% by weight, preferably 75 to 90% by weight. polyisocyanates.
  • the two-component binders described in combination with refractory and pourable fillers are suitable for producing a molding material according to the invention.
  • These natural and ceramic foundry sands are commonly referred to as basic molding materials. They include quartz sands of various origins and grain shapes, chromite sand, zircon sand, olivine sand, R sand, magnesia, alkali and alkaline earth halides, aluminum silicates such as J sand and Kerphalite®, synthetic sands such as Cerabeads®, fireclay, M sand, Alodur ®, bauxite sand, silicon carbide, expanded and foam glass, fly ash and other special sands.
  • the preferred mean grain size is in the range from 0.1 to 0.9 mm.
  • the binder and catalyst content in the mold material must be optimized taking into account the respective grain spectrum and the specific sand weight and is preferably 0.3 to 4.0% binder, based on the mold base material, and 0.001 to 2.5% catalyst, based on the resin component, discontinued.
  • the invention is not limited to these settings and amounts.
  • the amine gas-hardening molding material can be produced from one or more refractory pourable fillers at 96.0 to 99.7% and a binder at 0.3 to 4.0% in a batch or continuous mixer.
  • the resin and hardener components of the binder can be added in a mixing ratio of 2.5:1 to 1:2.5, depending on the respective recipe. However, for practical use in foundries, it has proven to be useful to formulate the binder systems in such a way that they can be used in a mixing ratio of 1:1, based on the mass.
  • the molding material is then introduced from a storage vessel into a core tool by applying compressed air at 2 to 7 bar and compressed, then cured in the core tool by a carrier gas-amine mixture, which preferably contains volatile, tertiary amines.
  • the temperature of the carrier gas/amine mixture is preferably in the range from 15 to 100.degree. After another flushing process with the carrier gas, the hardened molded part can be removed from the core tool without distortion be expelled.
  • Suitable volatile tertiary amines are trimethylamine, triethylamine (TEA), dimethylethylamine (DMEA), diethylmethylamine (DEMA), dimethylpropylamine (DMPA), dimethylisopropylamine (DMIPA) or mixtures of several amines.
  • the amines used are bases and have a pK B of 1 to 10, preferably 2 to 5.
  • the carrier gas is generally air but can also be an inert gas such as nitrogen or argon.
  • a molding material according to the invention does not contain any harmful aromatic solvents. Instead, preference is given to using fatty acid esters based on renewable raw materials, synthetic carboxylic acid esters, aliphatic carbonates and/or organic silicon compounds which do not contain any volatile components.
  • the binders and the molding materials themselves have advantageous processing properties such as odorlessness, low vapor pressure, low viscosity, good flowability, rapid hardening processes and high flexural strength.
  • the cores and molds produced with the molding materials described lead to advantageous casting properties and good disintegration. During casting, emissions of volatile organic compounds such as aromatic hydrocarbons and formaldehyde are also significantly reduced compared to binders based on phenol-formaldehyde resin.
  • FIG. 1 A comparison of binder emissions among pyrolytic
  • FIG. 1 shows a comparison of the emissions from binders (Examples 1 and 7, see below), which can be used in a molding material according to the invention, with a commercial, non-inventive, phenolic resin-based cold box binder (Example A2).
  • the measurements provide information about the chemical compounds formed during thermal decomposition of the binder under pyrolytic conditions. These are broken down as a percentage of the total quantity of emission products and classified according to substance class. For this purpose, measurements were carried out using the pyrolysis GC-FID or the pyrolysis GC/MS method at a decomposition temperature of 900°C. This method is established for the laboratory investigation of the pyrolytic decomposition products of polymers, such as the binders investigated here.
  • the present invention also shows benefits in terms of casting quality. Casting defects caused by the molding material are a major problem in iron and steel casting. A frequently occurring casting defect in iron casting is the so-called leaf rib. It arises because the quartz sand used as the basic molding material undergoes a modification change due to heating at 573 °C due to casting.
  • Molding materials according to the invention show a significant improvement compared to the binders used hitherto with regard to the casting defect tendency of the resulting cast part. This was examined and documented in detail for the blade vein casting defect described above. For this purpose, so-called dome cores are manufactured using the cold-box process, which, due to their geometry, provoke the development of the blade vein casting defect. Depending on the quality of the resulting casting, the casting defect tendency of the molding materials used can be classified.
  • compositions of the binders used in Examples 1 to 16 are shown below. All percentages [%] in this document are always to be understood as percentages by weight, unless a different definition is made in the explanatory text.
  • Example 1 Example 2: Example 3:
  • Example 6 Example 7:
  • the binders of the present invention are generally composed of a resin component consisting of a) polyester polyols, b) polycarbonate alcohols c) polyether polyols, d) short-chain crosslinkers and e) thinners, and also an isocyanate-containing hardener component.
  • polyester polyols in the resin component were varied from 0% to 74%, the polycarbonate alcohols from 0% to 46% and the sum of the polyester polyols and polycarbonate alcohols from 42% to 74%.
  • dihydric aliphatic alcohols such as ethylene glycol or 1,3-propanediol and trihydric representatives such as trimethylolpropane have been used by way of example.
  • water as a carbon-free substance or aromatic crosslinkers such as 2,2'-[1,3-phenylenebis(oxy)]bisethanol were also used. Combinations of these are also listed.
  • Fatty acid methyl esters with C16 to C18 fatty acids and/or dibasic esters were mostly used as diluents, but tetraethyl orthosilicate and caprolactone were also used.
  • the isocyanate content of the hardener component varied between 75% and 89%.
  • a hardener component was used in which 82 parts by weight of the MDI oligomer were reacted with 10 parts by weight of polyether polyol to give a prepolymer. Therefore, this hardener component already shows a slight development of the polymer network.
  • delimitation example A1 contains neither polyester polyols nor polycarbonate alcohols in the resin component.
  • the resin component consists exclusively of polyether polyols, short-chain crosslinkers, thinners and catalytically active additives.
  • the hardener component consists of isocyanate and thinner. As in the examples of the invention are no phenolic components and contain formaldehyde.
  • example A2 contains neither polyester polyols nor polycarbonate alcohols in the resin component. It is a classic example of the phenol formaldehyde resin based cold box binders currently used in foundries.
  • the total equivalent weights given relate to the groups which are hydrogen-active towards isocyanate. They were calculated from the weight percentages and equivalent weights of the individual ingredients.
  • the total equivalent weights also referred to as average equivalent weights, are calculated, for example, from the percentage content of OH and/or SH and/or NH groups in the individual components, taking into account their mass fractions in the mixture.
  • the viscosities of the components were determined using a Brookfield rotational viscometer in accordance with DIN EN ISO 2555:2018-09 in the unit mPas.
  • the binder test was based on method A described in VDG leaflet P73.
  • the molding material mixture was produced in a paddle mixer from 100 parts by weight quartz sand H32 and 0.8 parts by weight resin component and hardener component or from 100 parts by weight chromite and each 0.4 parts by weight resin component and hardener component.
  • three test specimens each measuring 22.4 x 22.4 x 185 mm were injected into the introduced shaping core tool and then cured according to the process conditions below with a carrier gas-amine mixture.
  • the molding material strengths of the test specimens obtained in this way are determined as a function of time using the LRu-2e universal strength testing apparatus from Multiserw.
  • the strength of the cores when they are removed from the core tool and then when the cores are cast is relevant. These correspond to the immediate strength or final strength (24-hour value) of the test specimens.
  • the warp-free handling and storability of the core removed from the core tool is important.
  • this is the case with a flexural strength of the test specimens of 100 N/cm 2 .
  • a flexural strength value of the test specimens of >280 N/cm 2 is considered favorable as the ultimate strength after 24 hours. This ensures that cores hardened in the cold box process can be used from light metal castings to cast steel.
  • Test specimens were shot at a shooting pressure of 4 bar with the molding material mixtures, which were produced according to the above-mentioned method, and gassed with tertiary amine at 0.5 bar and then flushed with air.
  • the amount of amine as well as the flushing time will vary according to the processes used:
  • Method 1 mass of DMEA per mass of molding material: 0.0045; rinsing time: 90 s; quartz sand H32;
  • Method 2 mass of DMEA per mass of molding material: 0.0045; rinsing time: 60 s; quartz sand H32;
  • Method 3 mass of DMEA per mass of molding material: 0.0045; rinsing time: 30 s; quartz sand H32; Method 4: mass of DMEA per mass of molding material: 0.0030; rinsing time: 90 s; quartz sand H32;
  • Method 5 mass of DMEA per mass of molding material: 0.0060; rinsing time: 120 s; quartz sand H32;
  • Method 6 mass of DMEA per mass of molding material: 0.0090; rinsing time: 300 s; quartz sand H32;
  • Process 7 mass of DMPA per mass of mold material: 0.0045; rinsing time: 90 s; quartz sand H32;
  • Method 8 mass of DMEA per mass of mold material: 0.0045; rinsing time: 90 s; chrome it.
  • molded material test specimens could be cured in accordance with methods 1 to 7 using amounts of amine customary in the cold box method. A suitability of the molding materials according to the invention for use in the cold box process was thus demonstrated.
  • example A1 which is not according to the invention.
  • the associated molding material test specimens could not be cured.
  • Test specimens could only be obtained by further increasing the amine mass used per molding material mass to 0.009 and the gassing time to 300 seconds.
  • these showed neither sufficient removal strengths nor final strengths.
  • Molded materials with the non-inventive binder Example A1 are therefore not suitable for use in the cold box process because the cycle times and amounts of amine are well outside the range required in the cold box process.
  • Table 1 shows the flexural strength of the standard test specimens in the cold box method.
  • the dome cores for assessing the inclination of the leaf veins were produced by mixing 100 parts by weight of quartz sand H32 and 0.8 parts by weight each of resin and hardener component in a paddle mixer and then introducing the molding material mixture into the dome core mould.
  • a school grading system is used here, which takes into account the number of leaf veins and their width and height. With a rating of 1, no veins may appear, with a rating of 2 only slight approaches to veining, with a rating of 3, a few veins or a slight one Expression, with grade 4 a medium number or clear development of the leaf veins, with grade 5 many or very pronounced leaf veins and with grade 6 very many or very pronounced leaf veins.
  • binders used according to the invention in Examples 1, 2 and 14 there were only weakly pronounced deposits of leaf veins (rating 2).
  • comparative example A2 phenolic resin binder CB
  • a significantly higher number and greater expression and branching of leaf veins were observed (rating 4).

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Abstract

L'invention concerne une matière moulée servant à fabriquer des noyaux selon la technique de la boîte froide, ladite matière à mouler comprenant les constituants suivants : - un liant à deux composants exempt de phénol ou de dérivé de phénol, à base de polyuréthane, contenant un composant résine, comprenant un ou plusieurs polyesterpolyols aliphatiques ou aromatiques ramifiés, constitués d'initiateurs diel ou triol aliphatiques ou aromatiques ramifiés ayant une ou plusieurs chaînes latérales ainsi que des acides di- et/ou tricarboxyliques aliphatiques et/ou aromatiques substitués ou non substitués ou leurs anhydres, et/ou un ou plusieurs alcools de polycarbonate ayant des poids équivalents compris entre 250 et 4000 g/val et des fonctionnalités hydroxy de l'ordre de 2 à 4 sous forme, en ce qui concerne les isocyanates, de composants à hydrogène actif, les ou les polyesterpolyols ramifiés et/ou les polycarbonates du composant résine du liant représentant une proportion de l'ordre de 35 à 100% en poids du composant résine, et un composant durcisseur comprenant un ou plusieurs polyisocyanates ainsi qu'une ou plusieurs charges coulantes réfractaires. L'invention concerne en outre un procédé permettant de durcir une telle matière à mouler. La matière à mouler peut être durcie selon la technique de la boîte froide par gazage avec des amines tertiaires dans des temps de cycles courts. La possibilité de remplacer des liants à résine de phénoluréthane jusqu'alors courants permet d'obtenir des avantages d'émission considérables lors de la combustion du liant liée à la coulée.
PCT/DE2021/100587 2020-07-09 2021-07-06 Matière à mouler pour fabriquer des noyaux et procédé pour durcir la matière à mouler WO2022008001A1 (fr)

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WO2009056320A1 (fr) 2007-10-30 2009-05-07 Ashland-Südchemie-Kernfest GmbH Mélange de matériaux de moulage de fluidité améliorée
WO2009065015A1 (fr) 2007-11-14 2009-05-22 University Of Northern Iowa Research Foundation Système de liant à base biologique
DE102008055042A1 (de) 2008-12-19 2010-06-24 Hüttenes-Albertus Chemische Werke GmbH Modifizierte Phenolharze
WO2011008362A1 (fr) 2009-07-16 2011-01-20 Ashland Licensing And Intellectual Property Llc Liant de fonderie comprenant un ou plusieurs cycloalcanes comme solvant
DE102012201971A1 (de) 2012-02-09 2013-08-14 Hüttenes-Albertus Chemische Werke GmbH Cold-Box-Bindemittelsysteme und Mischungen zur Verwendung als Additive für solche Bindemittelsysteme
DE102012103705A1 (de) 2012-04-26 2013-10-31 Ask Chemicals Gmbh Verfahren zur Herstellung von Formen und Kernen für den Metallguss sowie nach diesem Verfahren hergestellte Formen und Kerne
DE102013111626A1 (de) 2013-10-22 2015-04-23 Ask Chemicals Gmbh Formstoffmischungen enthaltend eine oxidische Bor-Verbindung und Verfahren zur Herstellung von Formen und Kernen
WO2016038156A1 (fr) 2014-09-10 2016-03-17 Hüttenes-Albertus Chemische Werke GmbH Système de liant à deux composants pour procédé "polyuréthane-boîte froide"
DE102015201614A1 (de) 2014-09-10 2016-03-10 Hüttenes-Albertus Chemische Werke GmbH Zweikomponenten-Bindemittelsystem für den Polyurethan-Cold-Box-Prozess
DE102015118428A1 (de) 2015-10-28 2017-05-04 Purinvent System Gmbh Phenol-Formaldehydharz-freie Bindemittel für Gießerei-Formsande
DE102017107531A1 (de) 2017-04-07 2018-10-11 HÜTTENES-ALBERTUS Chemische Werke Gesellschaft mit beschränkter Haftung Verfahren zur Herstellung von Gießformen, Kernen und daraus regenerierten Formgrundstoffen
DE102018100694A1 (de) 2018-01-12 2019-07-18 Ask Chemicals Gmbh Formaldehydreduziertes Phenolharzbindemittel

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