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
• • 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
  • C08G18/54—Polycondensates of aldehydes
  • C08G18/542—Polycondensates of aldehydes with phenols
• • 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
• • 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
  • C08G8/00—Condensation polymers of aldehydes or ketones with phenols only
  • C08G8/04—Condensation polymers of aldehydes or ketones with phenols only of aldehydes
  • C08G8/08—Condensation polymers of aldehydes or ketones with phenols only of aldehydes of formaldehyde, e.g. of formaldehyde formed in situ
  • C08G8/20—Condensation polymers of aldehydes or ketones with phenols only of aldehydes of formaldehyde, e.g. of formaldehyde formed in situ with polyhydric phenols
  • C08G8/22—Resorcinol
• • 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
  • C08G8/00—Condensation polymers of aldehydes or ketones with phenols only
  • C08G8/28—Chemically modified polycondensates
  • C08G8/36—Chemically modified polycondensates by etherifying

Definitions

• the present application relates to a two-component binder system for use in the polyurethane cold-box process, a mixture for curing by contacting with a tertiary amine (wherein the term "tertiary amine” in the context of this application also includes mixtures of two or more tertiary amines ), a method for producing a feeder, a foundry mold or foundry core, and feeders, foundry molds and foundry cores that can be produced according to this method, and the use of a two-component binder system or a mixture according to the invention for bonding a molding base material or a mixture of molding base materials in the polyurethane cold box process.
• tertiary amine in the context of this application also includes mixtures of two or more tertiary amines
• binder systems In the production of feeders, foundry molds and foundry cores cold-curing two-component binder systems are often used to bond the mold base material with polyurethane formation.
• These binder systems consist of two components, a (usually dissolved in a solvent) polyol having at least two OH groups in the molecule (polyol component) and a (dissolved in a solvent or solvent-free) polyisocyanate having at least two isocyanate groups in the molecule (polyisocyanate -Component).
• the two components which are separately added to a molding base to form a molding material mixture, react in the molded molding mixture in a polyaddition reaction to form a cured polyurethane binder.
• the curing takes place in the presence basic catalysts, preferably in the form of tertiary amines, which are introduced after forming the molding material mixture with a carrier gas in the mold.
• the polyol component is usually a phenolic resin dissolved in a solvent, i. a condensation product of one or more (optionally substituted) phenols with one or more aldehydes (especially formaldehyde).
• phenolic resin component is therefore hereinafter referred to as phenolic resin component.
• the polyisocyanate component used is a polyisocyanate having at least two isocyanate groups in the molecule in undissolved form or dissolved in a solvent. Preferred are aromatic polyisocyanates. In the case of a polyisocyanate component in the form of a solution, the concentration of the polyisocyanate is generally above 70%, based on the total weight of the polyisocyanate component.
• a molding material mixture is first prepared by mixing a granular molding base material with the two components of the above-described
• the proportions of the two components of the two-component binder system are preferably dimensioned such that, based on the number of OH groups, an excess of the NCO groups results
• Current bicomponent binder systems typically present an excess of NCO Up to 20%, based on the number of OH groups, of the total amount of binder (if appropriate, including the solvents and additives present in the binder components) in foundry cores and foundry molds is usually in the range of about 1% to 2%.
• the mass of Formgru used usually with feeders in the range of about 5% to 18% based on the other constituents of the feeder mass.
• the molding material mixture is then molded. Thereafter, with short-term gassing with a tertiary amine (where the term “tertiary amine” also includes mixtures of two or more tertiary amines), the catalyst used is the curing of the molded molding material mixture in the range of 0.035% to 0.1 1%, in each case based on the mass of molding material used. Based on the mass of binder, the required amount of catalyst in the form of tertiary amine is typically 3% to 15%, depending on the type of used tertiary amine, then the feeder, the Foundry core or the foundry mold taken from the mold and used for casting of metal, for example in the engine casting.
• the feeders, foundry cores or foundry molds already during the fumigation of a measurable strength (this is referred to as "initial strength” or “instantaneous strength”), which increases slowly after the end of fumigation to the final strength values.
• initial strength or “instantaneous strength”
• the highest possible initial strengths are desired so that the feeders, foundry cores or foundry molds can be removed as soon as possible after the fumigation of the mold and the mold is available again for a new operation available.
• Cold-curing two-component binder systems with polyurethane formation as described above are also used in the polyurethane no-bake process.
• the curing takes place under the action of a liquid catalyst in the form of a solution of a tertiary amine, which is added to the molding material mixture.
• Two-component binder system for use in the polyurethane cold box process are described, for example, in US Pat. No. 3,409,579, US Pat. No. 4,546,124, DE 10 2004 057 671, EP 0 771 599, EP 1 057 554 and DE 10 2010 051 567 and in the non-prepublished patent application PCT / EP2015 / 070,751th
• a two-component binder system for use in the polyurethane no-bake process is described, for example, in US Pat. No. 5,101,001.
• phenolic resin component consisting of a phenolic resin component and a separate polyisocyanate component, wherein the phenolic resin component comprises an ortho-fused phenolic resole having etherified and / or unetherified terminal methylol groups and a solvent and optionally one or more additives
• the polyisocyanate component comprises a polyisocyanate having at least two isocyanate groups per molecule and optionally a solvent and optionally one or more additives,
• the proportion of the mass of polyisocyanate is 90% or more, preferably 92% or more, more preferably 95% or more, particularly preferably 98% or more, in each case based on the total mass of the polyisocyanate component,
• the stoichiometric ratio of isocyanate groups in the polyisocyanate component to hydroxy groups in the phenolic resin component is less than 1, 2, and preferably in the range of 0.5 to ⁇ 1, particularly preferably in the range of 0, 7 to 0.95
• the phenolic resin component is free of compounds from the group of alkyl silicates and alkyl silicate oligomers
• the proportion of aromatic hydrocarbons is less than 39.43%, preferably less than 38%
• the proportion of rapeseed oil methyl ester is less than 39.43%, preferably less than 30%.
• hydrocarbons refers to organic compounds consisting only of carbon and hydrogen.
• the proportion of aromatic hydrocarbons is 35% or less, more preferably 30% or less, particularly preferably 25% or less,
• rapeseed oil methyl ester is 28% or less, more preferably 25% or less, particularly preferably 20% or less.
• binder systems of the invention have a long sand life, and at the same time allow a high initial strength of feeders, foundry cores or foundry molds.
• binder systems that provide high initial reactivity of feeders, foundry cores, and foundry molds have a relatively short sand life due to their high reactivity, while relatively long sand life binder systems provide lower initial strength of feeders, foundry cores, and foundry shapes because of their lower reactivity.
• the stoichiometric ratio of isocyanate groups in the polyisocyanate component to hydroxyl groups in the phenolic resin component is preferably in the range from 0.5 to 1.16, preferably in the range from 0.55 to 1, 1, more preferably in the range of 0.6 to 0.99, more preferably in the range of 0.7 to 0.95, particularly preferably in the range of 0.72 to 0.92, most preferably in the range of 0 , 75 to 0.9.
• the phenolic resin component and the polyisocyanate component are separated from each other, i. they are in separate containers, because the above-described addition reaction (polyurethane formation) between the resole of the phenolic resin component and the polyisocyanate of the polyisocyanate component should occur only when both components are mixed in a molding material mixture with a molding material or a mixture of several molding materials and this molding material mixture was molded.
• the phenolic resin component of the two-component binder system according to the invention contains a phenolic resin in the form of an ortho-condensed phenolic resole.
• a phenolic resin in the form of an ortho-condensed phenolic resole.
• Ortho-fused phenolic resole refers to a phenolic resin whose molecules have (a) methylene ether bridged ortho-linked aromatic rings formed from phenolic monomers and (b) ortho-positioned terminal (terminal) methylol groups
• Phenolic monomers includes both unsubstituted phenol and substituted phenols, for example cresols.
• ortho-position refers to the ortho-position with respect to the hydroxy group of the phenol It is not excluded that in the molecules of the present invention to be used ortho-fused phenolic resoles also linked by methylene aromatic rings (in addition to Methylene ether bridges linked aromatic rings (a)) and / or terminal hydrogen atoms in the ortho position (in addition to terminal methylol groups in ortho position (b)) are present.
• the ratio of methylene ether bridges to methyl bridges is at least 1
• the ratio of terminal (terminal) methylol groups in the ortho position to terminal hydrogen atoms in the ortho position is also at least 1.
• Such phenolic resins are also referred to as benzyl ether resins. They are obtainable by polycondensation of formaldehyde (optionally in the form of paraformaldehyde) and phenols in a molar ratio of greater than 1: 1 to 2: 1, preferably 1: 23: 1 to 1: 5: 1, catalyzed by divalent metal ions (preferably Zn 2+ ) in the weakly acidic medium.
• ortho-condensed phenolic resole includes compounds as described in the textbook "Phenolic Resins: A Century of Progress” (published by: L. Pilato, published by Springer , Year of publication: 2010), in particular on page 477 of FIG. 18.22.
• the term likewise includes the "benzyl ether resins (ortho-phenolic resoles)" specified in VDG leaflet R 305 "Urethane cold box process” (February 1998) under 3.1.1.
• the term also includes the "phenol resins of the benzyl ether resin type" disclosed in EP 1 057 554 B1, see in particular paragraphs [0004] to [0006].
• the ortho-condensed phenolic resole of the phenolic resin component to be used according to the invention has unetherified terminal methylol groups -CH 2 OH and / or etherified terminal methylol groups -CH 2 OR.
• an etherified terminal methylol group the hydrogen atom, which is bound to the oxygen atom in the unetherethered terminal methylol group -CH 2 OH, is replaced by a radical R.
• R is an alkyl radical, ie the groups - CH 2 OR are alkoxymethylene groups.
• alkyl radicals having one to four carbon atoms preferably from the group consisting of methyl, ethyl, propyl, n-butyl, i-butyl and tert-butyl.
• the radical R of the etherified terminal methylol group of the ortho-fused phenolic resole has the structure
• R1 is selected from the group consisting of hydrogen and ethyl R 2 is a radical formed from an ortho-fused phenolic resole as described above,
• the ortho-fused phenolic resole of the phenolic resin component is a modified resole comprising ortho-fused phenolic resole units formed as described above which are substituted and / or linked by esters of orthosilicic acid.
• Such resins are preparable by reacting unreacted hydroxy groups (i.e., hydroxyl groups of the unetherified terminal methylol groups) of an ortho-fused phenolic resole with one or more esters of orthosilicic acid.
• Such modified resols and their preparation are described i.a. described in the patent application WO 2009/130335.
• the ratio of unetherified terminal methylol groups to etherified terminal methylol groups is preferably greater than 1, preferably greater than 2, more preferably greater than 4, and most preferably greater than 10.
• Phenol resins with etherified methylol groups are also preferred in practice because they have a higher solubility in non-polar solvents such as aromatic hydrocarbons.
• it has been found that the objects of the present invention are better achieved when using an ortho-fused phenolic resole containing predominantly or even exclusively unetherified methylol terminal groups (as defined above).
• the phenolic resin component component of the two-component binder according to the invention comprises an ortho-fused phenolic resole having unetherified terminal methylol groups and a solvent and optionally one or more additives.
• the proportion of the ortho-fused phenolic resole in the phenolic resin component is preferably in the range of 30% to 50%, preferably in the range of 40% to 45%, based on the total mass of the phenolic resin component.
• the phenolic resin component of the two-component binder system of the invention comprises a solvent in which the above-described orthocondensed phenolic resole is dissolved.
• the solvent comprises the phenolic resin component
• Rapsölmethylester only in such an amount that based on the total mass of the phenolic resin component, the proportion of aromatic hydrocarbons is less than 39.43%, preferably less than 30%.
• the solvent of the phenolic resin component preferably comprises one or more compounds selected from the group consisting of
• saturated and unsaturated fatty acid alkyl esters preferably vegetable oil alkyl esters, preferably from the group consisting of rapeseed oil methyl ester, tall oil methyl ester, tall oil butyl ester (CAS No. 67762-63-4), lauric acid, isopropyl laurate (isopropyl laurate, CAS No .: 10233-13-3), myristate isopropyl (Isopropylmyristat CAS No .: 1 10-27-0) and myristic isobutyl ester (isobutyl mystrate (CAS NO .: 25263-97-2)
• Alkylene carbonates preferably propylene carbonate
• aromatic hydrocarbons from the groups consisting of alkylbenzenes, alkenylbenzenes, dialkylnaphthalenes, dialkenyl-naphthalenes Substances from the group consisting of cashew nut shell oil, components of cashew nut shell oil and derivatives of cashew nut shell oil, preferably cardol, cardanol and derivatives and oligomers of these compounds.
• the dialkyl esters of C 3 -C 6 dicarboxylic acids are preferably dimethyl esters of C 3 -C 6 - dicarboxylic acids, particularly preferably from the group consisting of dimethyl adipate, dimethyl glutarate, dimethyl succinate and dimethyl malonate.
• those selected from the group consisting of dialkyl-naphthalenes and dialkenyl-naphthalenes are not preferred because of the toxicity of such compounds.
• plant alkyl esters are preferred for their recovery from renewable resources.
• Preferred plant olalkyl esters are rapeseed oil methyl ester, tall oil methyl ester, tall oil butyl ester, methyl laurate, isopropyl laurate, isopropyl myristate and isobutyl myristate. Rape oil methyl ester is currently particularly preferred.
• the solvent comprises or consists of the phenolic resin component
• the solvent comprises or consists of the phenolic resin component
• alkylbenzenes and alkenylbenzenes and one or more vegetable oil alkyl esters from the group consisting of rapeseed oil methyl ester, tall oil methyl ester, tall oil butyl ester, methyl lauric acid, isopropyl acrylate, isopropyl myristate and
• the total mass of compounds from the group of aromatic hydrocarbons 5% to 35%, preferably 10% to 30%, particularly preferably 15% to 25%
• the total mass of compounds from the group of dialkyl esters of C 3 -C 6 -dicarboxylic acids 5% to 35%, preferably 10% to 30%, particularly preferably 15% to 25%,
• the total mass of fatty acid alkyl esters 1% to 30%, preferably 5% to 25% and particularly preferably 10 to 20%
• the total mass of compounds from the group of aromatic hydrocarbons 5% to 35%, preferably 10% to 30%, particularly preferably 15% to 25% and
• the total mass of compounds from the group of dialkyl esters of C 3 -C 6 -dicarboxylic acids 5% to 35%, preferably 10% to 30%, particularly preferably 15% to 25%, in each case based on the total mass of the phenolic resin component and
• the total mass of fatty acid alkyl esters 1% to 30%, preferably 5% to 25% and particularly preferably 10 to 20%
• the phenolic resin component of the two-component binder according to the invention at 20 ° C has a viscosity of at most 100 mPas, preferably of at most 50 mPas, each determined according to DIN 53019-1: 2008-09.
• the phenolic resin component of the two-component binder according to the invention preferably contains less than 5%, preferably less than 1% of monomers selected from the group consisting of monomeric unsubstituted phenol and monomeric substituted phenols, based on the total mass of the phenolic resin component.
• a low content of the phenolic resin component of the two-component binder of monomeric unsubstituted phenol and monomeric substituted phenols of the invention is desirable
• the content of monomeric unsubstituted phenol and monomeric substituted phenols in the phenolic resin components of conventional two component binders for use in the cold box process is on the order of 4% to 10% based on the total weight of the phenolic resin component
• the phenolic resin component of ortho-fused phenolic resole is typically 50% to 60%, preferably 52% to 55%, based on the total weight of the phenolic resin component.
• polyisocyanate present in the polyisocyanate component of the two-component binder system according to the invention having at least two isocyanate groups per molecule is preferably selected from the group consisting of diphenylmethane diisocyanate (methylene bis (phenyl isocyanate), MDI), polymethylene polyphenyl isocyanates (polymeric MDI) and their mixtures. If desired, polymeric MDI comprises molecules having more than two isocyanate groups per molecule.
• Isocyanate compounds may also be used as the polyisocyanate for the polyisocyanate component with at least two isocyanate groups per molecule, which furthermore have at least one carbodiimide group per molecule.
• Such isocyanate compounds are also referred to as carbodiimide-modified isocyanate compounds and are used i.a. in DE 10 2010 051 567 A1.
• the polyisocyanate component of the two-component binder system according to the invention contains no polyisocyanate in the form of isocyanate compounds having at least two isocyanate groups per molecule, which furthermore have at least one carbodiimide group per molecule.
• the polyisocyanate component of the two-component binder system of the invention comprises a solvent in which the above-described Polyisocyanate is dissolved with at least two isocyanate groups per molecule, or no solvent, so that the polyisocyanate contained in the polyisocyanate component is not dissolved.
• the solvent of the polyisocyanate component comprises one or more compounds selected from the group consisting of
• Alkyl silicates and alkyl silicate oligomers Alkyl silicates and alkyl silicate oligomers
• saturated and unsaturated fatty acid alkyl esters preferably vegetable oil alkyl esters, preferably from the group consisting of rapeseed oil methyl ester, tall oil methyl ester, tall oil butyl ester, methyl lauric acid, isopropyl acrylate,
• Alkylene carbonates preferably propylene carbonate
• aromatic hydrocarbons e.g. from the group consisting of alkylbenzenes, alkenylbenzenes, dialkylnaphthalenes, dialkenylnaphthalenes.
• the dialkyl esters of C 3 -C 6 dicarboxylic acids are preferably dimethyl esters of C 3 -C 6 - dicarboxylic acids, particularly preferably from the group consisting of dimethyl adipate, dimethyl glutarate, dimethyl succinate and dimethyl malonate.
• those selected from the group consisting of dialkyl-naphthalenes and dialkenyl-naphthalenes are not preferred because of the toxicity of such compounds.
• vegetable oil alkyl esters are preferred for their recovery from renewable resources.
• Preferred vegetable oil alkyl esters are rapeseed oil methyl ester, tall oil methyl ester, tall oil butyl ester, methyl lauric acid, isopropyl laurate, isopropyl myristate and isobutyl myristate. Rape oil methyl ester is currently particularly preferred.
• the solvent of the polyisocyanate component of the two-component binder according to the invention preferably does not comprise any compounds from the group consisting of alkyl silicates and alkyl silicate oligomers.
• the polyisocyanate component of the two-component binder according to the invention particularly preferably comprises no compounds from the group consisting of alkyl silicates and alkyl silicate oligomers.
• the solvent present in the polyisocyanate component in a small amount (10% or less, preferably 8% or less, more preferably 5% or less, more preferably 2% or less, in each case based on the total weight of the polyisocyanate component) essentially serves to protect the polyisocyanate from moisture.
• the polyisocyanate component of the two-component binder system according to the invention preferably contains only such an amount of solvent as is necessary for the reliable protection of the polyisocyanate from moisture.
• phenolic resin component and / or the polyisocyanate component comprises as additive one or more substances which are selected from the group consisting of
• Silanes e.g. Aminosilanes, epoxysilanes, mercaptosilanes and ureidosilanes and chlorosilanes,
• Acid chlorides e.g. Phosphoryl chloride, phthaloyl chloride and benzene phosphorous dichloride
• Additive mixture can be prepared by reacting a premix of (av) 1, 0 to 50.0 weight percent methanesulfonic acid
• esters of one or more phosphorus-oxygen acids the total amount of said esters being in the range of
• silanes selected from the group consisting of aminosilanes, epoxysilanes, mercaptosilanes and ureidosilanes, the total amount of said silanes being in the range of 5.0 to 90.0 percent by weight
• weight percentages are based on the total amount of the components (av), (bv) and (cv) in the premix.
• the proportion of water in a preferred variant is at most 0.1 percent by weight, the percentages by weight being based on the total amount of constituents (av), (bv) and (cv) in the premix.
• These additives essentially serve to extend the period of time during which the molding material mixture mixed with the two binder components can be stored prior to further processing into foundry molds or foundry cores despite the high reactivity of the binder system ("sand life") Additives that inhibit polyurethane formation Long sand lifetimes are needed so that a prepared batch of a molding material mixture does not become prematurely unusable
• the additives mentioned above are also known as “bench life extenders” and are known to the person skilled in the art from phosphoryl chloride POCl 3 (CAS No.
• o-phthaloyl chloride (1,2-benzenedicarbonyl chloride, CAS No. 88-95-9) and benzene phosphorous dichloride (CAS No: 842-72-6)
• suitable additives are methanesulfonic acid and phosphorus-oxyacids, preferably from Gru ppe consisting of phosphinic acid, phosphonic acid, phosphoric acid, peroxophosphoric acid, hypodiphosphonic acid, diphosphonic acid, hypodiphosphoric acid, diphosphoric acid and peroxodiphosphoric acid.
• a preferred sand life-prolonging additive is an additive blend preparable by reacting a premix of the above components (av), (bv) and (cv) as described in patent application WO 2013/1 17256.
• Inhibiting additives are usually added to the polyisocyanate component of the two-component binder system according to the invention. Their concentration is usually 0.01% to 2% based on the total weight of the polyisocyanate component. Hydrofluoric acid as an inhibiting additive is usually added to the phenolic resin component of the two-component binder system according to the invention.
• additives optionally contained in the phenol resin component and / or in the polyisocyanate component of the two-component binder system according to the invention are to facilitate the removal of hardened feeders, foundry cores and foundry molds from the mold and to increase the storage stability, in particular the Moisture resistance, manufactured feeders, foundry cores and foundry molds.
• Another aspect of the present invention relates to a mixture for curing by contacting with a tertiary amine.
• This mixture according to the invention according to the invention
• (a) can be prepared by mixing the components of the two-component binder system according to the invention as defined above,
• the stoichiometric ratio of isocyanate groups in the polyisocyanate component to hydroxy groups in the phenolic resin component is smaller than 1, 2, and preferably in the Range of 0.5 to ⁇ 1, more preferably in the range of 0.7 to 0.95
• the mixture (both in case (a) and in case (b)) is free of compounds from the group of alkyl silicates and alkyl silicate oligomers
• the proportion of rapeseed oil methyl ester is less than 27.6%, preferably less than 25%.
• the stoichiometric ratio of isocyanate groups in the polyisocyanate component to hydroxyl groups in the phenolic resin component is preferably in the range from 0.5 to 1.16, preferably in the range from 0.55 to 1.1, more preferably in the range from 0.6 to 0.99, more preferably in the range from 0.7 to 0.95, particularly preferably in the range from 0.72 to 0.92, very particularly preferably in the range from 0.75 to 0 , the ninth
• the proportion of aromatic hydrocarbons is 22% or less, more preferably 20% or less, particularly preferably 15% or less,
• the proportion of rapeseed oil methyl ester is 22% or less, more preferably 20% or less, particularly preferably 15% or less.
• Such a mixture according to the invention is useful for binding a masterbatch or mixture of masterbatch in the polyurethane cold box process (see below).
• the mixture according to the invention in particular in its preferred embodiments, is characterized in that it gives adequate strength in feeders, foundry molds and foundry cores produced in the polyurethane cold box process with a low binder content and addition of a small amount of tertiary amine. Due to the small amounts of binder and tertiary amine, the emissions, especially of BTEX aromatics (benzene, toluene, ethylbenzene, xylene), and the odor burden are limited.
• BTEX aromatics benzene, toluene, ethylbenzene, xylene
• Variant (a) of the mixture according to the invention as described above is preferably preparable by mixing the components of one of the above-described preferred two-component binder systems according to the invention.
• variant (b) of the mixture according to the invention as described above the above statements apply with regard to preferably used ortho-fused phenolic resoles, polyisocyanates, solvents, additives and mixing ratios.
• a further aspect of the present invention relates to a mixture as defined above, further comprising a molding base material or a mixture of several molding base materials, wherein the ratio of the total mass of molding base materials to the total mass of other components of the mixture in the range of 100: 2 to 100: 0.4, preferably from 100: 1, 5 to 100: 0.6.
• the other constituents of the mixture comprise all constituents of the mixture which are not molding materials, in particular all components of the two-component binder according to the invention, i. ortho-fused phenolic resole, polyisocyanate, solvent and optionally additives as defined above.
• Such a mixture according to the invention can be used as a molding material mixture for producing a foundry mold or a foundry core according to the polyurethane-cold-box process.
• This mixture according to the invention is characterized in that produced foundry molds and foundry cores have sufficient strength at a low binder content and with a small amount of tertiary amine necessary for curing. Due to the small amounts of binder and tertiary amine, the emissions, in particular of BTEX aromatics, and the odor pollution are limited.
• Suitable mold bases are all customary mold bases used for the production of feeders, foundry molds and foundry cores, for example quartz sand and special sands.
• the term special sand includes natural mineral sands as well as sintered and melted products, which are produced in granular form or transformed into granular form by crushing, grinding and classifying processes, or inorganic mineral sands formed by other physicochemical processes, which are used as molding bases be used with foundry usual binders for the production of feeders, cores and molds.
• Special sands include
• Aluminum silicates in the form of technical sintered ceramics such as e.g. Chamotte and cerabeads,
• non-oxide technical ceramics such as silicon carbide.
• a molding material mixture according to the invention which is suitable for producing a feeder according to the polyurethane cold box process, i. a feeder mass according to the invention
• (a) can be prepared by mixing the components of the two-component binder system according to the invention as defined above,
• the stoichiometric ratio of isocyanate groups in the polyisocyanate component to hydroxy groups in the phenol resin component is smaller than 1, 2, and is preferably in the range of 0.5 to ⁇ 1, more preferably in the range of 0.7 to 0.95
• the mixture (both in case (a) and in case (b)) is free of compounds from the group of alkyl silicates and alkyl silicate oligomers.
• the proportion of aromatic hydrocarbons is less than 27.6%, preferably less than 25% and the proportion of rapeseed oil methyl ester is less than 27.6%, preferably less than 25%.
• the feeder components comprise refractory granular fillers, optionally insulating fillers such as hollow microspheres, optionally fiber material, and in the case of exothermic feeders an oxidizable metal and an oxidizing agent for the oxidizable metal.
• the preparation of feeders by the polyurethane cold-box method and materials suitable as feed components are known to the person skilled in the art, see e.g. WO 2008/1 13765 and DE 10 2012 200 967.
• the stoichiometric ratio of isocyanate groups in the polyisocyanate component to hydroxyl groups in the phenolic resin component is preferably in the range from 0.5 to 1.16, preferably in the range from 0.55 to 1.1, more preferably in the range of 0.6 to 0.99, more preferably in the range of 0.7 to 0.95, more preferably in the range of 0.72 to 0.92, most preferably in the range of 0.75 to 0 , the ninth
• a further aspect of the present invention relates to a process for producing a feeder, a foundry mold or a foundry core from a molding material mixture, wherein the molding material mixture is bound by means of a two-component binder system according to the invention as defined above or by means of a mixture according to the invention as defined above.
• the molding material mixture to be used in the process according to the invention comprises a molding base material or a mixture of a plurality of molding base materials or, for the production of a feeder, the above-mentioned feeder components.
• a foundry mold or a foundry core from this molding material mixture of the molding material or the mixture of several molding materials by means of the present invention contained in the molding mixture two-component binder system as defined above or bound by means of the mixture contained in the molding mixture according to the invention as defined above .
• mold base all mold bases commonly used for the production of feeders, foundry molds and foundry cores are suitable as indicated above. The method according to the invention comprises the following steps
• the stoichiometric ratio of isocyanate groups in the polyisocyanate component to hydroxy groups in the phenolic resin component is less than 1, 2, and preferably in the range of 0.5 to ⁇ 1, more preferably in the range of 0.7 to 0.95
• the stoichiometric ratio of isocyanate groups in the polyisocyanate component to hydroxyl groups in the phenol resin component is preferably in the range of 0.5 to 1.16, preferably in the range of 0.55 to 1 , 1, more preferably in the range of 0.6 to 0.99, more preferably in the range of 0.7 to 0.95, particularly preferably in the range of 0.72 to 0.92, most preferably in the range of 0, 75 to 0.9.
• the forming of the molding material mixture is usually carried out by the molding material mixture is filled in a mold, blown or shot and then optionally compressed.
• the contacting of the shaped molding material mixture with a tertiary amine is preferably carried out according to the polyurethane cold box process.
• the tertiary amine is preferably selected from the group consisting of triethylamine, dimethylethylamine, diethylmethylamine, dimethylisopropylamine, dimethylpropylamine and mixtures thereof.
• the tertiary amines to be used are liquid at room temperature and are evaporated by heat supply for use in the polyurethane cold box process, and the vaporized tertiary amine is sprayed or injected into the mold.
• the reduction of the required amounts of tertiary amine is advantageous not only because of the lower odor load and the reduced cost due to the lower cost of materials, but also because of the correspondingly lower cost for the separation and recycling of tertiary amines.
• the process according to the invention in particular in its preferred embodiments, is characterized in that it allows the production of feeders, foundry molds and foundry cores with a low binder content and addition of a small amount of tertiary amine, without compromising the strength of the feeders, foundry molds and foundry cores ,
• the small amounts of binder and tertiary amine, the emissions, especially of BTEX aromatics, and the odor pollution are limited.
• Compared to the prior art smaller ratio of polyisocyanate in the polyisocyanate component to ortho-condensed phenolic resole with etherified and / or unetherified methylol groups in the phenolic resin component of the nitrogen content of the binder is reduced.
• the feeders, foundry molds or foundry cores according to the invention are characterized by a high strength at low binder content based on the total mass of the feeder, the foundry core or the foundry mold.
• a further aspect of the present invention relates to the use of a two-component binder system according to the invention as defined above or a mixture according to the invention as defined above for binding a molding base material or a mixture of molding base materials in the polyurethane cold box process.
• a two-component binder system according to the invention as defined above or a mixture according to the invention as defined above for binding a molding base material or a mixture of molding base materials in the polyurethane cold box process.
• molding material mixtures comprising a conventional mixture of molding materials and a two-component binder system comprising a polyisocyanate component and a phenolic resin component as described below are prepared in the cold box process test specimens in the form of bending bars and determines their initial bending strengths.
• test specimens (+ GF + bending strength standard specimens
• VDG leaflet P73 The production of the test specimens (+ GF + bending strength standard specimens) is carried out in accordance with VDG leaflet P73.
• the molding material is presented in a mixing container.
• the phenolic resin component and polyisocyanate component (amounts see Table 1) are then weighed in the mixing container so that they do not mix directly.
• the base molding material, phenolic resin component and polyisocyanate component are mixed in a paddle mixer (Multiserw, model RN10 / P) for 2 minutes at about 220 revolutions / minute to form a molding material mixture.
• the test specimens are produced using a universal core shooting machine LUT, which is equipped with a gasoman LUT / G, both from the company Multiserw.
• the finished molding material mixture is filled directly after its preparation described above in the shooting head of Kernsch manmaschine or initially stored for one hour in a sealed container.
• the parameters of the core shooting process are as follows: shot time: 3 seconds, delay time after shot: 5 seconds, shooting pressure: 4 bar (400 kPa).
• the test specimens are gassed for 10 seconds at a gassing pressure of 2 bar (200 kPa) with dimethylpropylamine (DMPA). It is then purged with air at a purge pressure of 4 bar (400 kPa) for 9 seconds.
• the flexural strength is measured with a LRu-2e Multiserw tester at specific times (15 seconds, one hour, 24 hours, see Table 2) after the end of the rinse.
• compositions of the two-component binder systems and molding material mixtures used are listed in Table 1.
• the phenolic resin component comprises a resol having unetherified terminal methylol groups, ie, terminal groups of structure -CH 2 OH, and a solvent comprising the constituents
• the phenolic resin component of Examples 1.1 and 2.1 contains as additives a silane and 40% hydrofluoric acid (the sand life-prolonging additive). In the other examples, the phenolic resin component contains no additives.
• the polyisocyanate component contains diphenylmethane diisocyanate (methylenebis (phenyl) isocyanate), MDI) as the polyisocyanate, as well as a sand life-prolonging additive and, as solvent, a mixture of aromatic hydrocarbons.
• diphenylmethane diisocyanate methylenebis (phenyl) isocyanate
• MDI methylenebis (phenyl) isocyanate
• solvent a mixture of aromatic hydrocarbons.
• the polyisocyanate component of Examples 1.1, 1.2 and 1.3 contains, as the sand life-prolonging additive, an additive mixture preparable by reacting a premix of the abovementioned components (av), (bv) and (cv) as described in the patent application WO 2013/1 17256 in an amount of 1, 2%, based on the total weight of the polyisocyanate component (Example 1 .1) or 1, 4%, based on the total weight of the polyisocyanate component (Examples 1 .2 and 1.3).
• the polyisocyanate component of Examples 2.1, 2.2 and 2.3 contains as the sand life-prolonging additive phosphorus oxychloride in an amount of 0.3%, based on the total weight of the polyisocyanate component.
• Examples 1.1 and 2.1 which are not according to the invention, the two components of the binder system were each used in a quantity and composition customary in the prior art, these examples therefore serve as a reference.
• the solvent content of the polyisocyanate component is reduced compared to the reference example and the solvent content of the phenolic resin component is increased compared to the reference example.
• the stoichiometric ratio of isocyanate groups in the polyisocyanate component to hydroxyl groups in the phenolic resin component is less than 1.2, in examples 1.3 and 2.3 even less than 1.
• BM binder (less solvent and additives).
• composition phenolic resin polyisocyanate composition molding material mixture Composition phenolic resin polyisocyanate composition molding material mixture
• the molding material mixtures according to the invention regardless of the additive used, a higher storage stability than in the reference examples. This can be seen from the fact that the flexural strengths of test specimens, produced from a molded material mixture according to the invention stored for one hour in a closed container, do not fall off relative to the corresponding flexural strengths of the cores which were produced from the freshly prepared molding material mixture according to the invention.

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• Polymers & Plastics (AREA)
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• General Chemical & Material Sciences (AREA)
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• 2016
  • 2016-03-09 DE DE102016203896.6A patent/DE102016203896A1/de not_active Withdrawn
• 2017
  • 2017-03-08 EP EP17712931.9A patent/EP3426709A1/de not_active Withdrawn
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