EP3368233A1 - Liant exempt de résine de phénol - formaldéhyde pour des sables de moulage de fonderie - Google Patents

Liant exempt de résine de phénol - formaldéhyde pour des sables de moulage de fonderie

Info

Publication number
EP3368233A1
EP3368233A1 EP16801698.8A EP16801698A EP3368233A1 EP 3368233 A1 EP3368233 A1 EP 3368233A1 EP 16801698 A EP16801698 A EP 16801698A EP 3368233 A1 EP3368233 A1 EP 3368233A1
Authority
EP
European Patent Office
Prior art keywords
component
binder
isocyanates
isocyanate
additives
Prior art date
Legal status (The legal status 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 status listed.)
Pending
Application number
EP16801698.8A
Other languages
German (de)
English (en)
Inventor
Sandra ESCHRICH
Renate Marquardt
Daniel HOLSTEIN
Katja KRELLIG
Frauke Petry
Tina HERTEL
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Bindur GmbH
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
Publication of EP3368233A1 publication Critical patent/EP3368233A1/fr
Pending legal-status Critical Current

Links

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
    • 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
    • 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
    • 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
    • C08G18/30—Low-molecular-weight compounds
    • C08G18/32—Polyhydroxy compounds; Polyamines; Hydroxyamines
    • C08G18/3271—Hydroxyamines
    • 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
    • C08G18/38—Low-molecular-weight compounds having heteroatoms other than oxygen
    • C08G18/3855—Low-molecular-weight compounds having heteroatoms other than oxygen having sulfur
    • C08G18/3876—Low-molecular-weight compounds having heteroatoms other than oxygen having sulfur containing mercapto 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
    • C08G18/28—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
    • C08G18/65—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
    • C08G18/6666—Compounds of group C08G18/48 or C08G18/52
    • C08G18/667—Compounds of group C08G18/48 or C08G18/52 with compounds of group C08G18/32 or polyamines of C08G18/38
    • C08G18/6674—Compounds of group 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
    • C08G18/6666—Compounds of group C08G18/48 or C08G18/52
    • C08G18/667—Compounds of group C08G18/48 or C08G18/52 with compounds of group C08G18/32 or polyamines of C08G18/38
    • C08G18/6681—Compounds of group C08G18/48 or C08G18/52 with compounds of group C08G18/32 or polyamines of C08G18/38 with compounds of group C08G18/32 or C08G18/3271 and/or polyamines of C08G18/38
    • C08G18/6688—Compounds of group C08G18/48 or C08G18/52 with compounds of group C08G18/32 or polyamines of C08G18/38 with compounds of group C08G18/32 or C08G18/3271 and/or polyamines of C08G18/38 with compounds of group C08G18/3271
    • 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
    • C08G18/7671—Polyisocyanates or polyisothiocyanates cyclic aromatic containing two or more aromatic rings containing alkylene polyphenyl groups containing only one alkylene bisphenyl group
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/04—Oxygen-containing compounds
    • C08K5/10—Esters; Ether-esters
    • C08K5/101—Esters; Ether-esters of monocarboxylic acids

Definitions

  • the invention relates to phenol-formaldehyde resin-free binders for foundry molding sands as well as molding mixtures of natural and / or ceramic sands with these binders. Due to the absence of phenol-formaldehyde resin and aromatic solvents, the binders are broad and neutral in health. They are suitable for the established core and mold manufacturing processes. The invention further relates to a form material hardening process.
  • lost foundry molds which are made from special foundry sands bonded with inorganic or organic binders and latently stable, has been in operation for more than half a century and has since then undergone a steady evolution to meet the growing demands of modern foundry technology to be able to.
  • the inorganic binders consist predominantly of mixed silicates with a major proportion of different types of waterglass, the composition of which decisively influences the curing behavior of the molding base material mixed therewith.
  • the organic binders used are predominantly phenolic, furan or urea resins or else mixtures thereof, catalysts for controlling the curing rate being added as required by the shaping process.
  • phenol-formaldehyde resins which consist of an OH-functional component A and a predominantly isocyanate-containing component B, which react with each other in admixture with the molding material to form polyurethane addition products and thereby the sand particles for the duration of the casting process.
  • the at least two free hydroxyl-carrying phenol-formaldehyde compounds of component A are diluted for the purpose of better processability with different functionally neutral extenders and other, the polyurethane reaction and / or the sand binding promotional additives mixed.
  • the B component also contains an at least difunctional isocyanate predominantly of the liquid diphenylmethane diisocyanate type.
  • WO 91/09908 and DE 29 23 840 A1 describe various binders based on phenolic resin-containing A components and isocyanate-containing B components and methods for their use.
  • various methods of core production are used when using phenol-formaldehyde resins.
  • Particularly widespread is the cold-box process, in which by amine fumigation an almost sudden hardening of the mold core is achieved and which is particularly suitable for an automated core manufacturing process.
  • the so-called cold box method is explained in numerous publications, such as, for example, US Pat. No. 3,409,579 A, DE 2 162 137 A and DE 1 959 023 A.
  • the no-bake or pep-set method dispenses with the environmentally relevant amine fumigation and achieves the curing of the binder / molding sand mixture by combining the reactive A and B components only immediately before introduction into the mold, depending on the nature the planned casting a catalyst is added in different concentrations, with which the curing of the molding material mixture can be accelerated.
  • the use of phenol-formaldehyde resin binder is associated with numerous significant disadvantages, which consist on the one hand in the physiological workload in all stages of processing and on the other hand in the environmental hazard of landfill polluted Altsande.
  • polyether polyols or similar hydroxyl-containing compounds.
  • polyether alcohols based on polyfunctional diamines are used as a minor component, such as US 4,273,700 A, to control reactivity in an otherwise phenolic resin-based system.
  • EP 1 375 028 A1 describes an analogous application, also in combination with glycol monoethers in the resin component. The addition of such aminopolyols has a positive effect on the form hardening material. On the other hand, this increases the nitrogen load in the binder.
  • the cold resin binder In order to adapt the processing properties of the cold resin binder to the requirements of the core impression, they are usually formulated by dilution with various solvents or fillers.
  • aromatic hydrocarbons such as Solvesso TM 100 and Solvesso TM 150 are used for this purpose due to their harmful emissions during processing and casting are problematic.
  • the object underlying the invention is to avoid the disadvantages of the phenol-formaldehyde-resin binder and to provide a binder for foundry sands, which can be completely dispensed with this class of substances as well as almost completely on commodities subject to labeling.
  • the invention is achieved by a binder system having the features of claim 1.
  • the solution of the object of the invention consists in a phenol-formaldehyde resin-free binder for foundry sands, wherein the binder either
  • a component A as a mixture of, with respect to isocyanates, hydrogen-active compounds, the hydroxyl and / or
  • Reactivity controlling functional additives and / or non-functional additives that is, the processability promoting and stability-securing non-functional admixtures
  • ⁇ as a one-component binder based on polyurethane and / or polyurea with contents of free isocyanate groups in the range from 5 to 35%, which is suitable for a multi-phase curing process using water-alcohol mixtures,
  • Component B of the two-component mixture corresponds to the isocyanate component of the two-component binder.
  • the average OH and SH functionality of a component A can be determined by calculation from the manufacturer-specified OH and SH functionalities of the pure substances used, for example polyols or polythiols.
  • the OH / SH functionality of a mixture of hydrogen-active compounds can be calculated by dividing the total number of all OH and SH groups of the hydrogen-active compounds in the mixture by the number of all OH and SH group-carrying molecules of the mixture ,
  • the total number of all OH groups of the hydrogen-active compounds in a mixture can be determined by titration in accordance with DIN 53240-2.
  • the content of free isocyanate groups in one-component binders can be computationally calculated from the NCO content of the isocyanate present and the respective proportion and equivalent weight of the hydrogen-active compounds used.
  • the content of free isocyanate groups can be determined experimentally by titration according to ASTM D5155.
  • ASTM American Society for Testing and Materials
  • ASTM International is the abbreviation for the original name of the international standardization organization ASTM International, whose main activity is the development of such standardized testing and analysis methods. In this way, pourable, odorless, easy to process, physiologically harmless and largely old sand-neutral organic binder are designed by the currently used and harmful phenol-formaldehyde resin-based binder not only partially, but completely substituted.
  • the invention makes use of the possibilities of highly specialized polyurethane chemistry by combining specifically innovative products of this polymer industry with one another to form novel binder components which, depending on the particular application of core production, are still enriched by special additives such as heteroatom-containing organic compounds and / or surfactants, their effects are targeted to be optimized.
  • the invention includes one-component and two-component systems, but in any case based on the polyurethane base reaction in which active hydrogen atoms react with isocyanate groups to polyurethane and / or polyurea structures.
  • the present invention avoids the use of aromatic solvents and instead prefers specific combinations of renewable raw material fillers and synthetic carboxylic acid esters and organic silicon compounds.
  • Binders produced in this way are virtually odorless, have a low vapor pressure, a process-friendly viscosity, give the molding base material good flowability, optimum curing speed and dimensional stability, and high strength values, which predestines it for core production.
  • the molds from the sprue to the cooling prove to be stable, but can be afterwards easily separated from the casting.
  • emissions are significantly lower in volatile organic compounds, aromatic hydrocarbons, and olfactory perceptible outgassing.
  • the two-component binders according to the invention are suitable both for the no-bake or pep-set and in special embodiments for the widely used cold-box method, preference being given to the no-bake or pep-set method is because it does without the environmentally relevant Aminbegasung.
  • the one-component systems according to the invention are cured in the binder molding sand mixture by a likewise inventive method in which water or water-alcohol mixtures are passed in liquid, gaseous or aerosolized form through the binder-sand mixture.
  • This process is based on the one hand on the reaction of isocyanates with water to form polyureas and on the other hand on the reaction of the alcohols with isocyanates to form closely crosslinked polyurethane structures, which give the molding sand a particularly strong structure.
  • the one-component binder preferably comprises an aromatic or aliphatic oligomeric and / or polymeric isocyanate or a mixture of a plurality of aromatic and / or aliphatic oligomeric and / or polymeric isocyanates with partially retarded reactivity, and as additive a functionless thinner, also referred to as extender, and optionally a catalyst.
  • the isocyanates of the one-component binder advantageously have at least the functionality 2.
  • the diphenylmethane diisocyanates or naphthylene diisocyanates generally have a higher reactivity than cycloaliphatic or aliphatic diisocyanates due to their aromatic structure, although there are still significant differences in reactivity depending on the isomer distribution.
  • Isocyanates with biuret or isocyanurate structures react in contrast to the aromatic isocyanates only at higher temperatures, which may be advantageous for specific applications.
  • tailor-made one-component binders can be designed which can be adapted to the respective intended use.
  • Isocyanates suitable for one-component binder systems include the Lupranate ® from the product range of BASF, the Desmodur ® grades from Bayer, the Voranate ® Dow Chemical, which Vestanate ® from Evonik, the Tolonate TM of Company Vencorex or Ongronate ® from BorsodChem.
  • suitable isocyanates include, in particular Lupranat ® M70R, Lupranat ® MM 103, Lupranat ® M 105, Lupranat ® MIP, Desmodur ® VLR20, Desmodur ® CD-S, Desmodur ® DN, Desmodur ® I, Desmodur ® W / 1, vestanate ® IPDI, vestanate ® H.sub.12MDI, vestanate ® TMDI, vestanate ® HT 2500 / LV, Tolonate TM HDB LV, Tolonate TM HDT LV, Ongronat ® 3800, Ongronat ® CR-30-20, Ongronat ® CR-30-40, Ongronat ® CR-30-60.
  • non-functional diluents such as fatty acid esters, synthetic carboxylic acid esters, sulfonic acid esters, Alkyl silicates and special
  • the reaction of the isocyanate group with water-promoting catalysts are largely storage-stable one-component binder systems produced in this way, which unfold their full reactivity only in contact with gaseous, liquid or aerosolized water or water-alcohol mixtures.
  • Suitable catalysts for this are, in addition to organotin and organoaluminum compounds, especially nitrogen-containing compounds, such as dimethylcyclohexylamine, N-substituted pyrrolidones, N-substituted imidazoles, triazine derivatives, diazabicyclooctane or quaternary ammonium salts in various formulations.
  • nitrogen-containing compounds such as dimethylcyclohexylamine, N-substituted pyrrolidones, N-substituted imidazoles, triazine derivatives, diazabicyclooctane or quaternary ammonium salts in various formulations.
  • Suitable tin catalysts include, for example, the Cosmos ® grades from Evonik, while King Industries offers a suitable aluminum-containing catalyst having a K-Kat ® 5218th With its Lupragen ® range, BASF offers a broad range of tertiary nitrogen catalysts.
  • a quaternary ammonium salt for catalyzing the polyurethane reaction for example, BYK ® -ES 80.
  • the isocyanates are reacted in a stoichiometric excess with certain polyols to prepolymers with a precisely determinable residual content of free isocyanate groups, which should be at least 5%.
  • Such pre-crosslinking is advantageously brought about by the reaction with a stoichiometric excess of di- or polyfunctional polyols and preferably results in a residual content of free isocyanate groups between 5 and 35%, particularly preferably between 6 and 30%.
  • such prepolymers must have a processing-friendly viscosity, which ensures good mixing with the molding base material and therefore a maximum of 900 mPas, but preferably 300 to 600 mPas, at 20 ° C. is.
  • Particularly suitable crosslinking polyols for the preparation of the prepolymers of the invention are long-chain di- or trifunctional polyether alcohols having molar masses of from 2000 to 6000 g / mol, which have been prepared by an alkali-catalyzed synthesis.
  • Such polyols include Voranol CP 6055 ® from Dow Chemical, the Desmophene ® BT 5031, 3900 and 3600Z from Bayer, the Lupranole ® 2090 from BASF 1000/1.
  • polyols having lower molecular weights for prepolymer formulation if the resulting viscosity can be kept below 1000 mPas at 20 ° C.
  • Such short-chain polyols are for example the Voranole ® P400 and CP 260 from Dow Chemical. Impact polyols are not suitable since the prepolymers produced with them do not have sufficient stability because of their residual content of catalysts.
  • prepolymer one-component systems is compared to the application-oriented selection of isocyanates another way to optimize the molding material-binder mixture targeted. In this way, for example, a significantly higher elasticity is achieved, which is of crucial importance for the manufacture of some core shapes.
  • the one-component binders are prepared by intensive mixing at room temperature with the exclusion of atmospheric moisture. It is essential to avoid the ingress of moisture during manufacture and also during the subsequent storage, otherwise the isocyanate contained in it will prematurely react. Partly pre-crosslinked one-component binders must deposit at least 24 hours prior to their use, but better three to five days after their preparation, so that the prepolymer formation can be completed, which can be controlled by determining the content of free isocyanate groups.
  • the core production with the one-component binder systems takes place after a curing process according to the invention, in which the molding material mixture of molding sand and binder with liquid and / or gaseous and / or aerosolized water-alcohol mixtures or is cured only with water, wherein the curing with water and / or water-alcohol mixtures in liquid, gaseous or aerosolized form in the temperature range from 20 to 150 ° C, preferably 20 to 120 ° C, and at pressures of 0.2 to 5 bar, preferably 0.5 to 2 bar, takes place.
  • the molding material mixture is brought into contact with water or with a water-alcohol mixture in a closed system at temperatures between 20 and 120 ° C, optionally with the application of pressure in accordance with the cold box method, and then with compressed air dry blown at a temperature between 20 and 120 ° C to expel excess water or excess alcohol from the core.
  • a water-alcohol mixture in a closed system at temperatures between 20 and 120 ° C, optionally with the application of pressure in accordance with the cold box method, and then with compressed air dry blown at a temperature between 20 and 120 ° C to expel excess water or excess alcohol from the core.
  • the cores produced in this way can be removed from the mold in the conventional cold box process immediately and have a very good compressive and flexural strength.
  • This water-alcohol method has the advantage that no harmful, odorous
  • alcohols come lower divalent representatives of this class or amino alcohols into consideration.
  • these alcohols include ethylene glycol, 1, 2-propanediol, 1, 3-propanediol, 1, 4-butanediol, 2,3-butanediol and aminoethanol to it.
  • the two-component systems according to the invention preferably consist on the one hand of component A with isocyanate-active individual compounds having a total functionality of 2.0 to 3.9, as additive (s), preferably a non-functional diluent or diluent, optionally a catalyst promoting the polyurethane reaction , optionally a stoichiometric amount of water and optionally Homogenmaschineszu accountsn and on the other hand from the component B with isocyanates.
  • component A balanced combinations of various aliphatic and / or cycloaliphatic compounds active in relation to isocyanate, in which case these compounds are polyols, such as polyether alcohols, Polyester alcohols, polyetheresteralcohols, furthermore polythiols, functional polysulfide polymers, amino alcohols, polyhydric alcohols and possibly also carboxylic acids.
  • the constituents of the isocyanate-active compounds of component A according to an advantageous embodiment of the invention, an average equivalent weight of 450 to 900 g / val, preferably 500 to 800 g / val.
  • the functionality of these hydrogen-active compounds must be at least 2.
  • the combination of difunctional with higher-functional compounds has proven to be advantageous, with optimum average functionality being sought.
  • the individual constituents of component A are combined so that an average OH / SH functionality of preferably 2.4 to 3.7 results.
  • the molecular weights of the hydrogen-active compounds and thus their equivalent weights to achieve an optimum average equivalent weight in the formulation of Include component A.
  • the selection and combination of these hydrogen-active compounds therefore takes place in such a way that their functionalities and their equivalent weights reflect a gradient.
  • optimum crosslinking is achieved within the polyaddition product, which is extremely advantageous for the processing properties of the molding material mixed therewith and for the adhesion between the sand particles.
  • Suitable hydrogen-active constituents for component A are virtually all commercially available polyether alcohols, amino alcohols, polyhydric alcohols and selected polyester alcohols, polythiols and functional polysulfide polymers, provided they have a readily processable viscosity, a low acid number and a minimum water content.
  • the hydrogen-active constituents of component A may be, for example, difunctional polyfunctional polyether alcohols, reactive and non-reactive polymer polyols, polyester alcohols, polyetherpolyester alcohols, polythiols, aminopolyether alcohols, di- and higher-functional alcohols, di- and higher-valent carboxylic acids and mixtures of all these individual components , Particularly suitable are two- to eight-functional polyether alcohols which are obtained by anionic or cationic ring-opening polymerization of cyclic ethers, such as propylene oxide, ethylene oxide, tetrahydrofuran and simultaneous addition of the resulting polyether chains to starting compounds such as ethylene glycol, 1,4-butanediol, glycerol, trimethylopropane, pentaerythritol, Glucose, sucrose, sorbitol, ethylenediamine, diethylenetriamine and other OH / NH-functional starter molecules are obtained, and polythiols resulting from the
  • Suitable polyols for the combination according to this invention are again long-chain polyols such Voranol ® CP6055 from Dow Chemical, the Desmophene ® 5031 BT, 3900 and 3600Z from Bayer, the Lupranole ® 2090 and 1000/1 by BASF, but also polyols with lower Molmassen, like the Voranole ® CP 260 and P400, the Lupranole ® 1100, 1200, 3300, 3423, 3902, the Desmophene ® 1300 BT 1380 BT 5401 B 21 AP25, the polyols 4640 and 4290 Perstorp among others.
  • SH-functional sulfur-containing additives the Thioplasttypen Akzo Nobel and Thiocure ® range of Bruno Bock have proved successful.
  • Suitable isocyanates for component B of the two-component binder are the aromatic, aliphatic and cycloaliphatic isocyanates described in the one-component process and their oligomers and polymers.
  • the isocyanates preferably have at least the functionality 2 and are oligomeric or polymeric variants of the basic type of 2,4'- and 4,4'-diphenylmethane diisocyanate and / or oligomeric or polymeric variants of the 2,4'- and 4,4-type '-Dicyclohexylmethane diisocyanates and / or oligomeric or polymeric derivatives of hexamethylene diisocyanate with optionally completely or partially blocked isocyanate groups and / or isophorone diisocyanate and / or its derivatives.
  • the isocyanates of component B are reacted in a stoichiometric excess with certain polyols to form prepolymers having a precisely determinable residual content of free isocyanate groups, which should be at least 5%.
  • Such a pre-crosslinking is advantageously brought about by the reaction with a stoichiometric deficit of di- or polyfunctional polyols, wherein preferably residual content of free isocyanate groups between 5 and 35%, particularly preferably between 6 and 30% results.
  • component B consists of mixtures of one isocyanate or more isocyanates with functionless extenders / diluents and the processability ensuring additives, the isocyanate content in the balanced Stoichiometric ratio to the hydrogen-active compounds of the component A is.
  • Both the one-component systems according to the invention and the two-component systems according to the invention are preferably supplemented and diluted with functionless, diluent-free extenders or diluents which are free of labeling in the sense of REACH.
  • extenders / diluents are, for example, fatty acid esters based on renewable raw materials, such as transesterification products of rapeseed oil, palm oil, soybean oil, argan oil, thistle oil, linseed oil or jatropha oil, especially their methyl, but also ethyl, propyl and isopropyl esters.
  • fatty acid ester of natural oils are the Rapsmethylester of Glencore and other established biodiesel producers, the palm and Sojamethylester the company Cremer, the Priolube TM grades Croda and RADIA ® esters from Oleon.
  • the possible applications of synthetic carboxylic acid esters include the product ranges of the Oxsoft ® and Oxblue ® esters from Oxea, Softenol ® esters from Sasol, the Caffaro dibenzoate esters designated as Freeflex, and the diluents which are very versatile and well suited for packaging, such as Mesamoll ® from Lanxess and Hexamoll ® DINCH ® from BASF is available.
  • diluents / diluents are organosilicates, in particular alkyl silicates and alkyl silicate oligomers, for example tetraethyl silicate, tetra-n-propyl silicate, trialkyl silicates, dialkyl silicates and monoalkyl silicates.
  • organosilicates in particular alkyl silicates and alkyl silicate oligomers, for example tetraethyl silicate, tetra-n-propyl silicate, trialkyl silicates, dialkyl silicates and monoalkyl silicates.
  • aromatics fractions from crude oil refining such as, for example, selected Tudalene ® by Hansen & Rosenthal, individually or in a mixture with the abovementioned excipients or diluents may be used.
  • Sulfonic acid ester suitable as extender / thinner.
  • the binders are processed with or without catalytic support.
  • substance classes described under the one-component binders namely organotin and organoaluminum compounds and tertiary or quaternary nitrogen-containing substances.
  • the additives for homogenization preferably consist of emulsifiers based on silicon or polyacrylate and / or cationic or anionic surfactants. These are anionic, amphoteric, nonionic and cationic surfactants and their specific embodiments, such as tertiary ammonium compounds of acrylic acid copolymers and selected polysiloxanes.
  • Known commercial products include BYK ® -P 9908, BYK ® -P 9909, Linda Linda neutral detergent GmbH or the surfactants of Impag and Julius Hoesch company.
  • the proportion of all additives is preferably 5 to 30 percent by weight, particularly preferably 10 to 25 percent by weight, based on the total of respective component A or B.
  • the preparation of the A and B components is carried out by intensive mixing of the individual components at room temperature and with exclusion of moisture.
  • the dry storage at room temperature is obtained in this way largely storage-stable two-component systems with process-friendly viscosity values of 300 to 600 m Pas / 20 ° C for the A side and 300 to 500 mPas / 20 ° C for the B side.
  • the one-component and two-component binders according to the invention are suitable for the common natural and ceramic foundry sands, such as quartz sands of various origins, chrome itsand, Mollithsand, Cerabeads and other basic molding materials.
  • the binder content must be optimized taking into account the respective grain spectrum and the specific sand weight and is preferably set between 1 and 2 wt .-% total content or 0.5 to 1 wt .-% per component for the two-component system. Other settings are possible.
  • the A and B components can be introduced in a mixing ratio of 2.5: 1 to 1: 2.5, depending on the recipe. However, for practical application in the foundry industry, it has proven expedient to formulate the binder systems such that they can be used in a mixing ratio of 1: 1.
  • the invention also relates to mixtures of natural and / or ceramic sands with the abovementioned one-component or two-component binders according to the invention.
  • the core production with the two-component systems can be carried out according to the no-bake or the cold-box method. That is, advantageously, the two-component binders are equally applicable to the no-bake and the cold-box method.
  • the suitability testing of the binder systems according to the invention was carried out in comparison with the established phenol-formaldehyde resin binders, specifically with the commercial and in the foundry largely established phenolic resin binder Pentex ® of Wilsontenes Albertus, Dusseldorf.
  • the strength values, the gaseous emissions during core production and casting with different melts as well as the landfill classifications resulting from the analysis of the spent sands discharged from the foundry process were compared.
  • VDG leaflets P 72 and P 73 The material for the sand analysis comes from technical experiments for manual core production and machine core shooting.
  • the casting objects were each pump impellers for different aggregates with different size dimensions.
  • the investigation of the nuclear fracture and burnt-up sands was carried out in accordance with the binding Landfill Ordinance (DepV, Annex 3, Table 2).
  • the measurement of gaseous emissions took place directly during technical core shooting and directly during casting with aluminum and gray cast iron.
  • the manufacture and measurement of the bending bars complies with VDG leaflet P72.
  • sand with in each case 0.5 to 1 parts by weight of component A and component B in a mixing ratio of 1: 1 and a catalyst in the form of a tin organyl or tertiary amine in an amount of 0, 1 to 1% by weight, based on the total Binder amount, mixed intensively for about one minute in a laboratory mixer with planetary gear.
  • the resulting molding material mixture was placed in a molding box for bending bars of 22.4 x 22.4 x 172 mm and allowed to cure.
  • Component A Component B Polyol Component Isocyanate Component
  • Viscosity at 20 ° C 470 mPas Viscosity at 20 ° C 370 mPas
  • Component A Component B Polyol Component Isocyanate Component
  • Viscosity at 20 ° C 470 mPas Viscosity at 20 ° C 90 mPas
  • the following table shows the flexural strengths of the flexural bars for selected systems compared with Pentex ® at 1.6% binder content using quartz sand H31. The values were measured at different time intervals after the production of the bending bars.
  • the sand life must be adjusted, which is achieved by adding reaction retarders to component B.
  • the molding material mixture with the reaction-retarded component B is first prepared analogously to the no-bake method and then transferred batchwise after a storage time of 1, 3 and 5 hours in the Biegestabschmannbüchse according to VDG leaflet P73 and there fumigated by method A with triethylamine and then rinsed with air.
  • Component A Component B Polyol Component Isocyanate Component
  • Viscosity at 20 ° C 470 mPas Viscosity at 20 ° C 170 mPas
  • composition binder 8 is also cold-box capable, that is, the sand-binder mixture can be stored for 2 h and then fumigated with the mist of water, 1, 4-butanediol and compressed air, without causing significant reductions in flexural strength.
  • Composition binder 8 is also cold-box capable, that is, the sand-binder mixture can be stored for 2 h and then fumigated with the mist of water, 1, 4-butanediol and compressed air, without causing significant reductions in flexural strength.
  • Polyether polyol MW 2000 5.0%
  • Polyether polyol MW 6000 10.0%
  • Polyether polyol MW 2000 10.0%
  • Polyether polyol MW 6000 10.0%

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Abstract

L'invention concerne des liants exempts de résine de phénol - formaldéhyde pour des sables de moulage de fonderie ainsi que des mélanges de matières à mouler constitués de sables naturels et/ou céramiques avec lesdits liants. Les liants selon l'invention ne sont pas nocifs pour l'environnement ni pour la santé grâce à l'absence de résine de phénol - formaldéhyde et de solvants aromatiques. Ils sont appropriés pour les procédés établis de fabrication de noyaux et de moules. L'invention concerne également un procédé de durcissement des matières à mouler. Le liant se présente : soit sous forme de liant bicomposant à base de polyuréthane et/ou de polyurée, comprenant un composant A sous forme de mélange de composés à hydrogène actif, par rapport aux isocyanates, qui contiennent des groupes hydroxyle et/ou mercapto, ayant une fonctionnalité moyenne OH et SH de 2,0 à 3,9, ayant un poids équivalent moyen de 450 à 900 g/val des produits de départ, et avec des additifs fonctionnels contrôlant la réactivité et/ou non fonctionnels, à savoir des additions non fonctionnelles favorisant l'aptitude à la transformation et garantissant la stabilité, ainsi qu'un composant B contenant des groupes isocyanate ; soit sous forme de liant monocomposant à base de polyuréthane et/ou de polyurée ayant des teneurs en groupes isocyanate libres dans la plage de 5 à 35 %, qui est approprié à un procédé de durcissement, utilisable de manière multiphase, au moyen de mélanges eau - alcool.
EP16801698.8A 2015-10-28 2016-10-28 Liant exempt de résine de phénol - formaldéhyde pour des sables de moulage de fonderie Pending EP3368233A1 (fr)

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DE102015118428.1A DE102015118428A1 (de) 2015-10-28 2015-10-28 Phenol-Formaldehydharz-freie Bindemittel für Gießerei-Formsande
PCT/DE2016/100509 WO2017071695A1 (fr) 2015-10-28 2016-10-28 Liant exempt de résine de phénol - formaldéhyde pour des sables de moulage de fonderie

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DE102018121769A1 (de) 2018-09-06 2020-03-12 HÜTTENES-ALBERTUS Chemische Werke Gesellschaft mit beschränkter Haftung Verfahren zur Herstellung eines metallischen Gussstücks oder eines gehärteten Formteils unter Verwendung eines aliphatischen Bindemittelsystems
DE102019123372A1 (de) 2019-08-30 2021-03-04 Bindur Gmbh Warmhärtender Formstoff zur Herstellung von Kernen und Formen im Sandformverfahren
DE102019123374A1 (de) 2019-08-30 2021-03-04 Bindur Gmbh Verfahren zur Herstellung von Kernen und Formen im Sandformverfahren
CN111848918B (zh) * 2020-06-28 2022-06-03 梅其勇 一种血管支架用可生物降解聚氨酯及其合成方法
DE102020118148A1 (de) 2020-07-09 2022-01-13 Bindur Gmbh Formstoff zur Herstellung von Kernen und Verfahren zu dessen Härtung

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