DE102006037288A1 - Use of cashew Nutshell derivatives in polyurethane based foundry binders - Google Patents

Abstract

The invention relates to a molding material mixture for the production of cores and molds for the foundry industry, comprising at least: - a refractory molding base and - a polyurethane-based binder system comprising a polyisocyanate component and a polyol component, said binder system comprising at least a portion of cashew nut shell oil, at least one component of cashew nutshell oil and / or at least one derivative of cashew nutshell oil.

Description

The Invention relates to a molding material mixture for the production of moldings for the foundry industry, a method for producing a mold using the Molding material mixture, a casting mold, as well as the use of the mold for the Metal casting.

molds for the Production of metal bodies are manufactured essentially in two versions. A first Group form the so-called nuclei and forms. Out of these becomes the mold composed, which is essentially a negative mold of the produced casting wherein cores are used to form cavities inside the casting, while the forms the outer boundary represent. Often, only the inner cavities are imaged by nuclei, while the outer contour of the casting through a greensand form or a steel mold is shown. Form a second group Hollow body, so-called feeders, which act as balancing reservoir. These take liquid Metal on, by taking appropriate measures to ensure that the metal longer in the liquid Phase remains as the metal, which is in the negative mold forming mold located. If the metal solidifies in the negative mold, it can become liquid metal from the balancing reservoir flow to the solidification compensate for the volume contraction occurring in the metal.

molds consist of a refractory material, such as quartz sand, its grains after the molding of the mold be connected by a suitable binder to a sufficient mechanical strength of the mold to ensure. For the Production of casting molds So you use a refractory molding material, which with a suitable binder is added. The mold base material and binder obtained molding material mixture is preferably in one pourable Form before, so that they are filled in a suitable mold and can be condensed there. The binder becomes a solid Cohesion between the particles of the molding base material, so that the mold obtains the required mechanical stability.

to Production of casting molds can both organic and inorganic binders are used, their hardening by cold or hot Procedure can be done. Cold processes are called Method, which essentially at room temperature without heating the molding material mixture performed become. The curing This is usually done by a chemical reaction, for example triggered that can be a gaseous Catalyst through the to be hardened Molding material mixture is passed, or by the molding material mixture a liquid Catalyst is added. In hot processes, the molding material mixture heated to a sufficiently high temperature after shaping, for example, the solvent contained in the binder drive out or to initiate a chemical reaction, by which the binder is cured by crosslinking.

Becoming present for the Production of casting molds many organic binders, such as e.g. Polyurethane, furan resin or epoxy-acrylate binders, in which the curing of the Bindemittels by addition of a catalyst. binder On the basis of polyurethanes are generally made of two components constructed, wherein a first component consists of a phenolic resin and the second component of a polyisocyanate. These two Components are mixed with the molding base and the molding material mixture brought into shape by ramming, blowing or another method, compacted and then hardened. Depending on the method with which the catalyst in the molding material mixture is introduced, a distinction is made between the "polyurethane no-bake process" and the "polyurethane cold box process". When no-bake procedure becomes a liquid Catalyst, generally a liquid tertiary amine, introduced into the molding material mixture, before they are brought into a mold and cured becomes. The conditions are chosen so that the ready-made Molding material mixture has a sufficiently long processing time, within which the shaping can be carried out. The polymerization must be slow accordingly, so not already in the storage containers or supply lines a cure the molding material mixture takes place. On the other hand, the curing must not be too be done slowly to ensure a sufficiently high throughput during production of molds to reach. At the

Cold-box process is the molding material mixture first placed in a mold without catalyst. Through the molding material mixture will follow a gaseous tertiary Amine passed, which optionally mixed with an inert carrier gas can be. Upon contact with the gaseous catalyst, the binder binds very fast, allowing a high throughput in the production of molds is achieved.

In the US 3,409,579 a binder composition is described which is a mixture of a resin component, a curing component and a curing agent. The resin component comprises a phenolic resin obtained by condensing a phenol and an aldehyde. The phenolic resin is dissolved in an organic solvent. The curing component comprises a liquid polyisocyanate having at least two isocyanate groups. As a curing agent, the binder comprises a tertiary amine. For the production of moldings, first the phenolic resin component and the polyisocyanate component are mixed with a refractory molding material. The molding material mixture is subsequently brought into a mold. To cure the molding material mixture is passed through these normally at room temperature, the gaseous curing agent, for example trimethylamine, dimethylethylamine, dimethylisopropylamine or triethylamine. For better vaporizability, the tertiary amine can be heated. After curing, the mold can be removed.

In the US 3,676,392 there is described a resin composition comprising a phenol resin component dissolved in organic solvents, a curing agent component, and a curing catalyst. The hardener component used is a liquid polyisocyanate comprising at least two isocyanate groups. The polyisocyanate is used in an amount of 10 to 500% by weight based on the weight of the resin. As the curing catalyst, a base having a pK _b in the range of about 7 to about 11 and used in an amount of 0.01 to 10% by weight based on the resin is used.

For the production of molds be phenolic resin, polyisocyanate and curing catalyst with the refractory Mixed molding material. This can be done in the way that the mold base material first is wrapped with one component of the binder and then the other Component is added. The curing catalyst is thereby one of the components added.

in welcher A, B und C Wasserstoff, Halogen oder Kohlenwasserstoffreste, die auch über ein Sauerstoffatom an den Phenylring gebunden sein können, bedeuten, mit einem Aldehyd der allgemei nen Formel R'CHO, in welcher R' für ein Wasserstoffatom oder einen Kohlenwasserstoffrest mit 1 bis 8 Kohlenstoffatomen steht, bei einem molaren Verhältnis von Aldehyd zu Phenol von größer als eins in flüssiger Phase bei wasserfreien Bedingungen und Temperaturen von unterhalb 130 °C in Gegenwart katalytisch wirksamer Mengen eines im Reaktionsmedium löslichen zweiwertigen Metallsalzes umgesetzt. Bei der Umsetzung entsteht ein Gemisch aus Dimethylolverbindungen der folgenden Formeln:

in welchen R für Wasserstoff oder einen in meta-Stellung zur phenolischen OH-Gruppe angeordneten phenolischen Rest steht, sowie höher kondensierte Verbindungen der Formel:

in welcher R die oben angegebene Bedeutung aufweist, die Summe von m und n zumindest zwei ergibt und das Verhältnis m/n zumindest eins ergibt. Ferner steht X für eine endständige Gruppe, die ausgewählt ist aus Wasserstoff und einer Methylolgruppe, wobei das molare Verhältnis von endständigen Methylolgruppen zu endständigem Wasserstoff zumindest eins beträgt. Zur Herstellung des Phenolharzes können unsubstituiertes Phenol, wie auch substituierte Phenole verwendet werden.Both in the in the US 3,409,579 described cold box method as well as in the US 3,676,392 phenol resins are used as polyols obtained by condensation of phenol with aldehydes, preferably formaldehyde, in the liquid phase at temperatures up to about 130 ° C in the presence of catalytic amounts of metal ions described no-bake method. The preparation of such phenolic resins is for example in the US 3,485,797 described. Phenols of the general formula are used for the preparation of the phenolic resins

in which A, B and C are hydrogen, halogen or hydrocarbon radicals which may also be bonded via an oxygen atom to the phenyl ring, with an aldehyde of the general formula R'CHO, in which R 'is a hydrogen atom or a hydrocarbon radical with 1 to 8 carbon atoms, reacted at a molar ratio of aldehyde to phenol of greater than one in the liquid phase at anhydrous conditions and temperatures below 130 ° C in the presence of catalytically effective amounts of a soluble in the reaction medium divalent metal salt. In the reaction, a mixture of dimethylol compounds of the following formulas is formed:

in which R stands for hydrogen or a phenolic radical arranged in the meta position to the phenolic OH group, as well as higher condensed compounds of the formula:

in which R has the meaning given above, the sum of m and n is at least two and the ratio m / n is at least one. Further, X is a terminal group selected from hydrogen and a methylol group, wherein the molar ratio of terminal methylol groups to terminal hydrogen is at least one. Unsubstituted phenol as well as substituted phenols may be used to prepare the phenolic resin.

In the WO 85/05580 For example, a binder composition comprising a resin component, a polyisocyanate curing agent component, and an amine curing component is described. The resin component is formed by a phenol resin obtained by condensing a phenol component and an aldehyde component. At least one mole percent of the phenolic component is formed by an alkyl-substituted phenol, preferably o-cresol or p-nonylphenol.

As a further reaction component, aliphatic monoalcohols can be added in the preparation of the phenolic resin. So will in the EP 0 177 871 describes a polyurethane binder containing as polyhydroxy a phenolic resole resin which is modified with alkoxy groups. The resole resin comprises at least one alkoxymethylene group per six phenolic cores. The alkoxymethylene groups are introduced by adding monohydric primary or secondary alcohols during synthesis of the resole resin. The alcohols comprise one to 8 carbon atoms, with methanol being particularly preferred. The alkoxymethylene groups have the general formula - (CH ₂ O) _n R where R is the alkyl group of the alcohol and n is a small integer. The alkoxymethylene groups are located ortho or para to the phenolic hydroxy group. By alkoxylation, the binder systems are to obtain increased thermal stability.

In order to be able to apply the polyhydroxy component and the polyisocyanate component in a thin film uniformly on the grains of the molding material, the components are diluted with solvents. In order to achieve a compatibility of the components, usually aromatic solvents are used, but some of which can develop a harmful effect. In the EP 0 771 599 A1 polyurethane-based binder systems containing methyl esters of higher fatty acids as solvents are described. Particularly suitable is Rapeseed oil methyl ester used as the sole solvent. A further advantage is that molds which are produced using this binder system can be removed particularly easily from the mold.

Cashew nutshell oil accumulates during the extraction of cashew nuts and continues in its na natural form of anacardic acid and cardol in a weight ratio of about 9: 1 together. Both components have a straight hydrocarbon chain with fifteen carbon atoms, in which predominantly simple and conjugated double bonds are. Technical cashew nut shell oil is obtained from the natural product by heating under acidic conditions. Decarboxylation of the anacardic acid results in a mixture of Cardanol and Cardol, also known as CNSL (Cashew Nutshell Liquid). In the thermal treatment, oligomers of these compounds, which remain in the distillation bottoms and can be isolated from this arise. Cashew nut oil and its derivatives are used in a number of technical manufacturing processes.

In the DE 42 33 802 A1 For example, there is described a rubber composition for the production of automotive tires, which comprises 100 parts by weight of a rubber component comprising one or more of natural rubber, polyisoprene rubber, polybutadiene rubber and styrene-butadiene rubber, 50 to 70 parts by weight of carbon black average particle size of less than 40 nm, 5 to 20 parts by weight of novolak-modified phenolic resin, 0.5 to 2 parts by weight of hexamethylenetetramine and 5 to 20 parts by weight of a polymeric cardanol having a viscosity of 20,000 to 50,000 mPas , The rubber composition has a relatively low stiffness before vulcanization and a relatively high modulus of elasticity after vulcanization, making it particularly suitable for use as a tire bead filler.

In the DE 39 01 930 A1 describes a process for the preparation of novolaks, wherein phenols or mixtures of phenols are reacted with oxo compounds by condensation of the reactants in a water-poor medium in homogeneous phase. The reaction takes place at temperatures above 110 ° C. and preferably at atmospheric pressure in the presence of water-immiscible and / or only partially water-miscible inert organic solvents, such as toluene, xylene, diethylbenzene or alcohols, such as butanol. As a catalyst, strong mineral acids can be used, such as sulfuric acid. The water added, for example, in the form of an aqueous formaldehyde solution and the water formed during the condensation is distilled off continuously during the reaction, preferably by azeotropic distillation with recycling of the entraining agent. The work-up of the reaction solution, which consists essentially of novolak, unreacted phenol and entrainer, is carried out by vacuum distillation, the distillation conditions determining the residual content of phenol.

As oxo compounds aldehydes and ketones can be used, which form condensation products with phenols. Suitable aldehydes are, for example, formaldehyde, acetaldehyde and their homologs or isomers having up to 18 carbon atoms per molecule. As the phenolic component, it is possible to use all phenolic compounds which have at least one reactive hydrogen atom on the aromatic nucleus and are at least monofunctional in their reactivity with aldehydes. Preferably, phenol itself, the various cresol and xylene isomers, and p- or o-substituted alkylphenols having up to 18 carbon atoms in the side chain are used. It is also possible to use unsaturated phenols, such as o- or p-vinylphenol, and the C ₁₅ -unsaturated alkenylphenols obtainable by distillation of cashew nut shell oil. The novolaks obtainable by the process can be used, for example, as reinforcing resins for rubber and elastomers. For this they are incorporated together or separately with crosslinking agents, such as hexamethylenetetramine and / or aminoplasts and / or resoles, optionally after a preliminary reaction, in the not yet vulcanized rubber or elastomer mixture. Further fields of use include friction linings, impregnating agents for organic and inorganic fibers, coatings, coatings and lacquers, and a use as a binder for comminuted, preferably inorganic materials.

In the DE 100 04 427 describes a process for the preparation of polyurethanes using a Cashew nut shell oil whose double bonds have been previously at least partially saturated, for example with sulfur or peroxides. The saturation is carried out only to the extent that no excessive increase in the viscosity occurs, that is, a good liquid product is obtained, which can be easily mixed with an isocyanate. The reaction with the polyisocyanate can be carried out with the cashew nut shell oil alone or with a mixture of the saturated cashew nut shell oil and other polyols and / or soybean oil, wherein the content of the cashew nut shell oil is at least 30, in particular at least 60% by weight. The polyisocyanate used is preferably diisocyanates, for example diphenylmethane-4,4'-diisocyanate (MDI).

In the DE 101 58 693 A1 there is described a granular material coated with a resin obtained by reacting an isocyanate component with a polyol component. The polyol component contains at least one compound selected from cardol, cardanol, as well as derivatives or oligomers of these compounds. The coating is permeable to water, but insoluble in water. Be more preferably, fertilizers are coated with the resin so as to achieve release of the fertilizer into the soil over an extended period of time. As the polyhydroxy component, Cardol and Cardanol are used by themselves or in the form of oligomers which can be obtained, for example, by reaction with formaldehyde or acid, in particular glyoxylic acid. The coating of the granules takes place for example in a rotating drum, in which the material to be coated is kept in motion during the entire coating process.

In the previously for the preparation of cores and molds used binder systems are still more or less big Contain proportions of unreacted phenol or formaldehyde. Because these substances are harmful to your health are trying to the content of the resins in these toxic monomers preferably far to humiliate. In many cases succeeds by a change the reaction, for example, by prolonged Condensation and / or distillation times. These measures However, they also bring considerable disadvantages. So increases at a longer Condensation time the viscosity the resins and their storage stability decreases. By a extended Vacuum distillation, the yield is degraded and valuable Monomers are distilled off useless.

Around casting defects to be avoided, to the strength and dimensional stability the form or cores high demands. The moldings should especially at higher levels Temperatures remain dimensionally stable. Such higher temperatures become, for example when drying a coating achieved from a refractory material, which is applied to the molding has been. Likewise, the molding should while the casting process remain stable and the loads caused by the inflowing liquid metal can be resisted.

Of the The invention was therefore based on the object, a molding material mixture from which moldings can be made, the a high stability even under thermal stress, and preferably one very low content of harmful Has residual monomers.

These Task is with a molding material mixture with the features of the claim 1 solved. advantageous embodiments the molding material mixture are the subject of the dependent claims.

It has been shown to increase by adding cashew nut shell oil or Derivatives of cashew nutshell oil to the binder molding for the foundry industry can be obtained which have a high thermal stability. As a further advantage let yourself the content of monomers still contained in the polyol component are, in particular phenol and formaldehyde, significantly reduce Lich. In the processing of the molding material mixture and in particular in casting process are therefore compared to molding mixtures from the prior Technique liberated lower levels of monomers. The monomers often have a harmful health Effect, so that by the smaller amount of released monomers also the burden of harmful Substances in the workplace in the foundry can be reduced.

Under a cashew nut shell oil is within the meaning of the invention, both from seed husks of the cashew tree recovered oil which is about 90% anacardic acid and about 10% cardol exists, as well as the technical Cashew nutshell oil, which from the natural Product is obtained by heat treatment in an acidic environment, and that contains Cardanol and Cardol as its main components.

Suitable components of the binder are the cashew nut shell oil itself, in particular the technical cashew nut shell oil, as well as the components obtained therefrom, in particular Cardol and Cardanol, and mixtures thereof and their oligomers, as used, for example, in the distillation of Ca Shewnussschalenöl remain in the swamp. These compounds can also be used in technical quality. The mixture of essentially cardanol and cardol, which is also known as cashew nutshell liquid (CNSL), formed during the distillation of cashew nut shell oil is preferably used. The double bonds of cardanol and cardol contained in the side chain may be partially or fully reacted with hydroxyl groups, epoxide groups, halogens, acid anhydrides, diclyclopentadiene or hydrogen. These groups can in turn be reacted with nucleophiles. In polyvalent cashew nutshell oil derivatives, the phenolic OH groups can also be completely or partially derivatized, for example by addition of ethylene oxide or propylene oxide units. These derivatives of cashew nut shell oil can also be used according to the invention in the molding material mixture.

The cashew nutshell or the compounds derived therefrom can be used as a separate component be contained in the binder. These components act as reactive Solvent, during curing of the binder in the resulting crosslinked polymer with. In this embodiment of the Inventive molding material mixture In particular, a high stability of the moldings at elevated temperature reached. How test bars, from the molding material mixture according to the invention have been prepared, under thermal stress a lower Deflection as a test bar, which have been prepared with an analogous binder, wherein however, no cashew nut shell oil had been added to the binder.

• – einen feuerfesten Formgrundstoff; und
• – ein Bindemittelsystem auf Polyurethanbasis, welches eine Polyisocyanatkomponente sowie eine Polyolkomponente umfasst,

wobei das Bindemittelsystem zumindest einen Anteil an Cashewnussschalenöl, zumindest einer Komponente des Cashewnussschalenöls und/oder zumindest eines Derivats des Cashewnussschalenöls enthält.The molding material mixture according to the invention for the production of cores and molds for the foundry industry comprises at least:

• A refractory base molding material; and
• A polyurethane-based binder system comprising a polyisocyanate component and a polyol component,

wherein the binder system contains at least a portion of cashew nut shell oil, at least one component of cashew nut shell oil, and / or at least one derivative of cashew nut shell oil.

When refractory molding material can in itself all refractories are used for the manufacture of moldings for the Foundry industry are common. Examples of suitable refractory mold bases are quartz sand, Zircon sand, olivine sand, aluminum silicate sand and chrome ore sand their mixtures. Preferably, quartz sand is used. The refractory Molding material should have a sufficient particle size, so that the molded body produced from the molding mixture a sufficiently high porosity has a fleeting escape Connections during the casting process to enable. Preferably, at least 80 wt .-%, more preferably at least 90 wt .-% of the refractory base molding material has a particle size ≤ 290 microns. The average particle size of the refractory The molding material should preferably be between 100 and 350 μm.

The Contains binder as essential components a polyol component and a polyisocyanate component.

The Polyisocyanate component of the binder system may be an aliphatic, cycloaliphatic or aromatic isocyanate. The polyisocyanate contains preferably at least two isocyanate groups, preferably 2 to 5 isocyanate groups per molecule. Depending on the desired Properties can also mixtures of isocyanates are used. The used Iso cyanate can consist of mixtures of monomers, oligomers and polymers and are therefore referred to below as polyisocyanates.

When Polyisocyanate component can be used per each polyisocyanate which is common in polyurethane binders for molding compounds for the foundry industry. Suitable polyisocyanates include aliphatic polyisocyanates, e.g. Hexamethylene diisocyanate, alicyclic polyisocyanates, e.g. 4,4'-dicyclohexylmethane diisocyanate, and dimethyl derivatives hereof. Examples of suitable aromatic polyisocyanates are toluene-2,4-diisocyanate, Toluene-2,6-diisocyanate, 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate, Xylylene diisocyanate and methyl derivatives thereof, diphenylmethane-4,4'-diisocyanate and Polymethylene polyphenylene polyisocyanates.

Although in principle all conventional polyisocyanates can react with the phenolic resin to form a crosslinked polymer structure, aromatic polyisocyanates are preferably used, more preferably polymethylene-polyphenyl polyisocyanates, such as the commercially available mixtures from diphenylmethane-4,4'-diisocyanate, its isomers and higher homologs.

The Polyisocyanates can both in substance or dissolved be used in an inert or reactive solvent. Preferably, the polyisocyanates are used in dilute form, because of the lower viscosity the solution the grains of the refractory base molding material better with a thin film envelop the binder to be able to.

The Polyisocyanates or their solutions in organic solvents are used in sufficient concentrations to cure the Polyolkomponente accomplish, usually in one area from 10 to 500% by weight, based on the weight of the polyol component. Preference is given to 20 to 300% by weight, based on the same base, used. liquid Polyisocyanates can in undiluted Form to be used while solid or viscous polyisocyanates in organic solvents solved become. Up to 80 wt .-% of the isocyanate component can from solvents consist.

When solvent for polyisocyanates are preferred high-boiling aromatic and aliphatic hydrocarbons and high-boiling fatty acid esters or mixtures of these substances used. Suitable aromatic solvent are alkyl-substituted benzenes, alkyl-substituted naphthalene and Mixtures thereof. The alkyl substituents preferably have 1 to 6 carbon atoms. The boiling point of the solvent or solvent mixture is preferably at least 150 ° C. Examples of suitable solvents are toluene, xylene, ethylbenzene and mixtures thereof, as well as high boiling aromatic hydrocarbon fractions.

Prefers the polyisocyanate is used in an amount such that the number the isocyanate groups 80 to 120%, based on the number of free Hydroxyl groups of the phenolic resin is.

When Polyol component can all polyols used in polyurethane binders are used. Contains the polyol component at least two hydroxyl groups with the isocyanate groups of the polyisocyanate component can react, in order to achieve crosslinking of the binder during curing, and thereby a better strength of the cured molded body.

When Polyol are preferably used phenolic resins by condensation of phenol with ketones or aldehydes, preferably formaldehyde, in liquid Phase at temperatures up to about 160 ° C in the presence of catalytic Amounts of metal ions are obtained.

The Polyol component is preferably liquid or in organic solvents solved used to ensure a homogeneous distribution of the binder on the To allow refractory molding material. The polyol component is preferably used in anhydrous form, since the reaction the isocyanate component with water is an undesirable side reaction. Not aqueous or anhydrous in this context, a water content of Polyol component of preferably less than 5 wt .-%, preferably less than 2% by weight.

By "phenolic resin" is the reaction product of phenols, phenol derivatives and bisphenols, as well as higher phenol condensation products understood with an aldehyde or ketone. The composition of the Phenol resin is dependent from the specifically selected Starting materials, the ratio of these starting materials and the reaction conditions. For example, play the type of catalyst, the time and the reaction temperature one important role, as well as the presence of solvents and other substances.

The Phenolic resin is typically a mixture of various compounds before and can in very different proportions addition products, Condensation products and unreacted starting compounds such as phenols, bisphenol and / or aldehyde.

As "addition products" are reaction products understood, in which an organic group at least one hydrogen substituted on a previously unsubstituted phenol or a condensation product. "Condensation products" are reaction products understood with two or more phenolic rings.

Condensation reactions of phenols with aldehydes result in phenolic resins, which are divided into two product classes, the novolacs and resoles, depending on the proportions of the starting materials, the reaction conditions and the catalysts used:
Novolacs are soluble, meltable, non-self-curing, and shelf-stable oligomers having one molecular moiety in the range of about 500-5,000 g / mol. They are obtained in the condensation of aldehyde and phenol in a molar ratio of 1:> 1 in the presence of acidic catalysts. Novolacs are phenol resins free of methylol groups in which the phenyl nuclei are linked via methylene bridges. They may be cured at elevated temperature with the addition of curing agents, such as formaldehyde donating agents (preferably hexylmethylenetetramine).

resols are mixtures of hydroxymethylphenols linked via methylene and methylene ether bridges and by reaction of aldehyde and phenols in the molar ratio of 1: <1, optionally in the presence of a catalyst, e.g. a basic catalyst, available are.

The phenolic resins which are particularly suitable as the polyol component are the term "o-o" or "high-ortho" novolak or benzyl ether known. These are weak by condensation of phenols with aldehydes Acid medium using suitable catalysts available.

to Preparation of Benzyletherharzen suitable catalysts are salts divalent ions of metals, such as Mn, Zn, Cd, Mg, Co, Ni, Fe, Pb, Ca and Ba. Preferably, zinc acetate is used. The used Quantity is not critical. Typical amounts of metal catalyst amount 0.02 to 0.3 wt .-%, preferably 0.02 to 0.15 wt .-%, based on the total amount of phenol and aldehyde.

to Preparation of the phenolic resins are all conventionally used phenols suitable. In addition to unsubstituted phenol, substituted phenols or mixtures thereof. The phenolic compounds are either in both ortho positions or in an ortho- and unsubstituted in the para position to the polymerization enable. The remaining ring carbon atoms may be substituted. The vote the substituent is not particularly limited as far as the substituent the polymerization of the phenol and the aldehyde is not detrimental affected. Examples of substituted phenols are alkyl-substituted Phenols, alkoxy-substituted phenols and aryloxy-substituted phenols.

The The abovementioned substituents have, for example, 1 to 26, preferably 1 to 15 carbon atoms. Examples of suitable phenols are o-cresol, m-cresol, p-cresol, 3,5-xylene, 3,4-xylene, 3,4,5-trimethylphenol, 3-ethylphenol, 3,5-diethylphenol, p-butylphenol, 3,5-dibutylphenol, p-amylphenol, cyclohexylphenol, p-octylphenol, p-nonylphenol, 3,5-dicyclohexylphenol, p-crotylphenol, p-phenylphenol, 3,5-dimethoxyphenol and p-phenoxyphenol.

Especially phenol itself is preferred. Also higher fused phenols, such as Bisphenol A, are suitable. About that In addition, polyhydric phenols having more than one phenolic hydroxyl group are also suitable. Preferred polyhydric phenols have 2 to 4 phenolic hydroxyl groups on. Specific examples of suitable polyhydric phenols are catechol, Resorcinol, hydroquinone, pyrogallol, phloroglucinol, 2,5-dimethylresorcinol, 4,5-dimethylresorcinol, 5-methylresorcinol or 5-ethylresorcinol.

It can also mixtures of different mono- and / or polyvalent and / or substituted and / or condensed phenolic components for the preparation the polyol component can be used.

zur Herstellung der Phenolharz-Komponente verwendet, wobei A, B und C unabhängig voneinander aus einem Wasserstoffatom, einem verzweigten oder unverzweigten Alkylrest (der beispielsweise 1 bis 26, vorzugsweise 1 bis 15, Kohlenstoffatome aufweisen kann), einem verzweigten oder unverzweigten Alkoxyrest (der beispielsweise 1 bis 26, vorzugsweise 1 bis 15, Kohlenstoffatome aufweisen kann), einem verzweigten oder unverzweigten Alkenoxyrest (der beispielsweise 1 bis 26, vorzugsweise 1 bis 15, Kohlenstoffatome aufweisen kann), einen Aryl- oder Alkylarylrest, wie beispielsweise Bisphenyle, ausgewählt sind.In one embodiment, phenols of general formula I:

used for the preparation of the phenolic resin component, wherein A, B and C independently of one another from a hydrogen atom, a branched or unbranched alkyl radical (which may have, for example 1 to 26, preferably 1 to 15, carbon atoms), a branched or unbranched alkoxy (for example 1 to 26, preferably 1 to 15, carbon atoms), a branched or unbranched alkenoxy radical (having, for example, 1 to 26, preferably 1 to 15, carbon atoms can), an aryl or alkylaryl radical, such as bisphenols, are selected.

Suitable aldehydes for the preparation of the phenolic resin component are aldehydes of the formula R-CHO wherein R is a hydrogen atom or a carbon atom radical having preferably 1 to 8, particularly preferably 1 to 3 carbon atoms. Specific examples are formaldehyde, acetaldehyde, propionaldehyde, furfuraldehyde and benzaldehyde. Particularly preferably, formaldehyde is used, either in its aqueous form, as paraformaldehyde or trioxane.

Around To obtain the phenolic resins should be at least equivalent Number of moles of aldehyde, based on the number of moles of the phenol component, be used. The molar ratio is preferably aldehyde Phenol 1: 1.0 to 2.5: 1, more preferably 1.1: 1 to 2.2 : 1, in particular preferably 1.2: 1 to 2.0: 1.

The Preparation of the phenolic resin component takes place according to the person skilled in the art known methods. It is, as already in the discussion of the The prior art describes the phenol and the aldehyde or the ketone under essentially anhydrous conditions in the presence a divalent metal ion at temperatures of preferably less than 130 ° C implemented. The resulting water is distilled off. This can a suitable entraining agent is added to the reaction mixture, For example, toluene or xylene, or the distillation at reduced Pressure performed become.

For the binder of the molding material mixture according to the invention, the phenol component is preferably reacted with an aldehyde to form benzyl ether resins. The reaction with a primary or secondary aliphatic alcohol to form an alkoxy-modified phenolic resin in the one-stage or two-stage process ( EP-B-0 177 871 and EP 1 137 500 A1 ) is also possible. In the one-step process, the phenol, aldehyde or ketone and alcohol are reacted in the presence of a suitable catalyst. In the two-step process, an unmodified resin is first prepared, which is subsequently reacted with an alcohol. When using alkoxy-modified phenolic resins, there is no limitation on the molar ratio per se, but the alcohol component is preferably used in a molar ratio of alcohol: phenol of less than 0.25 so that less than 25% of the hydroxymethyl groups are etherified. Suitable alcohols are primary and secondary aliphatic alcohols having one hydroxy group and 1 to 10 carbon atoms. Suitable primary and secondary alcohols are, for example, methanol, ethanol, propanol, n-butanol and n-hexanol. Particularly preferred are methanol and n-butanol. The use of novolaks as phenolic resin components is also possible.

The Phenolic resin is preferably chosen that crosslinking with the polyisocyanate component is possible. For the Building a network are phenolic resins containing molecules with at least two hydroxyl groups per molecule include, particularly suitable.

The Phenolic resin component of the binder system is preferred as solution in an organic solvent or a combination of organic solvents. solvent can be required to use the components of the binder in one sufficiently low viscous state to keep. This is u.a. required to uniform wetting of the refractory base molding material and its flowability to obtain.

All solvents which are conventionally used in binder systems for foundry technology can be used in the binder system of the molding material mixture according to the invention. Suitable solvents for the phenolic resin component are, for example, oxygen-rich, polar, organic solvents and nonpolar, aprotic solvents, such as high-boiling aromatic hydrocarbons (in particular in the form of mixtures) having a boiling point of more than 150 ° C. Particularly suitable are dicarboxylic acid esters, glycol ether esters, glycol diesters, glycol diethers, cyclic ketones, cyclic esters or cyclic carbonates. Dicarboxylic acid esters, cyclic ketones and cyclic carbonates are preferably used. Dicarboxylic acid esters have the formula R ^a OOC-R ^b -COOR ^a , wherein the radicals R ^{a are} each independently an alkyl group having 1 to 12, preferably 1 to 6, carbon atoms and R ^{b is} an alkylene group having 1 to 12, preferably 1 to 6, carbon atoms. Examples are dimethyl esters of carboxylic acids having 4 to 10 carbon atoms which are available, for example, under the name "Dibasic Ester" (DBE) from DuPont. Glycol ether esters are compounds of the formula R ^c -OR ^d -OOCR ^e , where R ^{c is} an alkyl group having 1 to 4 carbon atoms, R ^{d is} an ethylene group, a propylene group or an oligomer of ethylene oxide or propylene oxide and R ^{e is} an alkyl group having 1 to 3 carbon atoms is; preferred are glycol ether acetates (eg butyl glycol acetate). Glycol diesters accordingly have the general formula R ^e COO-R ^d -OOCR ^e where R ^d and R ^{e are} as defined above and the radicals R ^{e are} each independently selected; preferred are glycol diacetates (eg, propylene glycol diacetate). Glykoldiether can be through the For mel R ^c -OR ^d -OR ^c characterize, wherein R ^c and R ^{d are} as defined above and the radicals R ^{c are} each independently selected (eg dipropylene glycol dimethyl ether). Cyclic ketones, cyclic esters and cyclic carbonates of 4 to 5 carbon atoms are also suitable (eg propylene carbonate). The alkyl and alkylene groups may each be branched or unbranched. Also esters of long-chain fatty acids, as in the EP-A-1 137 500 described, can be used. Suitable fatty acids are, for example, having 8 to 22 carbon atoms, which are esterified with an aliphatic alcohol. Usually, fatty acids of natural origin, such as tall oil, rapeseed oil, sunflower oil, germ oil and coconut oil, are used. Instead of natural oils and fats, it is also possible to use individual fatty acids, such as palmitic acid or oleic acid. The aliphatic alcohols used are preferably primary alcohols having 1 to 12 carbon atoms, particularly preferably 1 to 10 carbon atoms, particularly preferably 4 to 10 carbon atoms, with methanol and n-butanol being particularly preferred. Have proven themselves in the EP-B-0 295 262 "symmetrical esters" wherein both the acid moiety and the alcohol moiety have a number of carbon atoms (about 6 to 13 carbon atoms) in the same range.

Esters of long-chain fatty acids, a mixture of dimethyl esters of C ₄ -C ₆ -dicarboxylic acids (DBE), symmetrical esters and cyclic ketones are preferably used in the present invention in addition to high-boiling hydrocarbons.

Prefers forms the at least one component of cashew nut shell oil and / or the at least one derivative of cashew nutshell oil contains at least a portion of the Polyol. In this embodiment, the at least a component of cashew nut shell oil and / or the at least one derivative of cashew nutshell oil while the synthesis of the polyol component added so that they during the Synthesis are incorporated into the polyol component. The synthesis the polyol component is carried out in a known manner, wherein the at least one component of cashew nut shell oil and / or the at least one derivative of cashew nut shell oil already at the beginning of the synthesis or even later Time of synthesis can be added to the reaction mixture.

Especially Preferably, the polyol component is by condensation of a phenolic Component and an oxo component, wherein the cashew nut shell oil containing at least a component of cashew nut shell oil and / or the at least one Derivative of cashew nutshell oil forms at least a portion of the phenolic component.

The Synthesis of the polyol component is used in the above for the preparation the phenol resin described manner, but in addition to the Phenolkomponente the cashew nut shell or the at least one Component of cashew nutshell oil or the at least one derivative of cashew nut shell oil as further Component is added. As phenolic component, the phenols described above, as the oxo component described above Aldehydes and ketones are used.

Of the Proportion of cashew nutshell oil, the at least one component of the cashew nut shell oil and / or the at least one derivative of cashew nut shell oil on the phenolic component is preferably 0.5-20.wt .-%, particularly preferably 0.75 to 15 wt .-%, particularly preferably 1 to 10 wt .-%.

The cashew nutshell, whose components or derivatives can be used at any time Synthesis are added to the reaction mixture. Preferably takes place the addition already at the beginning of the synthesis.

Of the Proportion of the solvent The binder system is preferably chosen as low as possible. Prefers becomes the solvent content on the polyol component therefore less than 50% by weight, especially preferably less than 40 wt .-% selected. The dynamic viscosity of the polyol component, for example, determined by the Brookfield rotary spindle method can be preferably less than 1000 mPas, more preferably less as 800 mPas, and more preferably less than 600 mPas.

Cashew nutshell oil, components of cashew nutshell oil and derivatives of cashew nut shell oil can also be the isocyanate component be added, and they also with a part of the isocyanate groups can react.

Of the Proportion of the binder system (polyol and isocyanate component), based on the weight of the refractory molding base, is preferably between 0.5 and 10% by weight, preferably between 0.8 and 7% by weight selected.

In addition to the constituents already mentioned, the binder systems may contain conventional additives, eg silanes ( EP-A-1137500 ) or internal release agents, eg fatty alcohols ( EP-B-0 182 809 ), drying oils ( US-A-4,268,425 ) or complexing agent ( WO 95/03903 ) or mixtures thereof.

suitable Silanes are, for example, aminosilanes, epoxysilanes, mercaptosilanes, Hydroxysilanes and ureidosilanes, such as γ-hydroxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) trimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane.

suitable Release agents are in particular those already described above fatty acid ester, wherein the butyl ester of oleic acid and the tall oil fatty acid as well the mixed octyl / decyl ester of tall oil fatty acid is particularly preferred.

For the production the molding material mixture can first combining the components of the binder system and then are added to the refractory molding base. However, it is also possible, the components of the binder simultaneously or sequentially to give to the refractory molding material. For a uniform mixture To achieve the components of the molding material mixture, conventional methods be used. In addition, the molding material mixture may optionally have other conventional ingredients such as iron oxide, milled flax fibers, wood flour granules, Bad luck and refractory Flours, included.

• – Bereitstellen der oben beschriebenen Formstoffmischung;
• – Ausformen der Formstoffmischung zu einem Formkörper;
• – Aushärten des Formkörpers durch Zugabe eines Aushärtungskatalysators.

As a further subject matter, the invention relates to a process for producing a shaped body, comprising the steps:

• - Providing the molding material mixture described above;
• - Forming the molding material mixture into a shaped body;
• - Curing of the molding by adding a curing catalyst.

For the production of the molded article, the binder is first mixed with the refractory molding base material to form a molding material mixture as described above. If the molding is to be produced by the PU-No-Bake process, a suitable catalyst can also already be added to the molding material mixture. For this purpose, liquid amines are preferably added to the molding material mixture. These amines preferably have a pK _B value of 4 to 11. Examples of suitable catalysts are 4-alkylpyridines wherein the alkyl group comprises 1 to 4 carbon atoms, isoquinoline, arylpyridines such as phenylpyridine, pyridine, acridine, 2-methoxypyridine, pyridazine, 3-chloropyridine, quinoline, N-methylimidazole, 4,4'-dipyridine , Phenylpropylpyridine, 1-methylbenzimidazole, 1,4-thiazine, N, N-dimethylbenzylamine, triethylamine, tribenzylamine, N, N-dimethyl-1,3-propanediamine, N, N-dimethylethanolamine, and triethanolamine. The catalyst may optionally be diluted with an inert solvent, for example an aromatic hydrocarbon. The amount of catalyst added is selected in the range of 0.5 to 15% by weight based on the weight of the phenolic resin.

The Molding compound mixture is then mixed with conventional Means introduced into a mold and compacted there. The shaped one Molding compound mixture is subsequently to a shaped body hardened. When curing should the shaped body prefers its outer shape to keep. According to one Another preferred embodiment takes place the curing after the PU cold box process. This is a gaseous catalyst passed through the molded molding material mixture. As a catalyst, the usual Catalysts can be used in the field of cold box process. Particular preference is given to using amines as catalysts, in particular preferably dimethylethylamine, dimethyl-n-propylamine, dimethylisopropylamine, Dimethyl-n-butylamine, triethylamine and trimethylamine in their gaseous form or as an aerosol.

Of the Moldings produced by the method can in itself each the usual form in the foundry industry exhibit. In a preferred embodiment, the shaped body is in Form of foundry molds or cores.

Further The invention relates to a shaped body, as with the above-described Procedure can be obtained. This is characterized by a high mechanical stability, especially at higher levels Temperatures, as well as a low content of harmful residual monomers, whereby the development of quality during metal casting can be reduced.

Further The invention relates to the use of this molding for metal casting.

The The invention will be further described with reference to preferred embodiments explained in more detail.

Example 1 (not according to the invention):

In one with reflux condenser, thermometer and stirrer equipped reaction vessel 698.4 g of phenol, 302.6 g of paraformaldehyde (91%) and 0.35 g of zinc acetate dihydrate submitted. While stirring the temperature is at 105-115 ° C elevated and held until a refractive index (25 ° C) of about 1.5590 is reached. Thereafter, the condenser is switched to distillation and the temperature increased to 124-126 ° C within one hour. at this temperature is reached until reaching a refractive index (25 ° C) of approx. Distilled 1.5940. Then vacuum is applied and at reduced Pressure distilled to a refractive index (25 ° C) of about 1,600. The yield is about 85%.

Example 2-4 (according to the invention)

• *: nicht erfindungsgemäß
• **: erfindungsgemäß

Example 1 is repeated, but after reaching a refractive index (25 ° C) of about 1.5590, the amount of CNSL (Palmer 1500-1, Palmer International, USA) indicated in Table 1 is added. The further synthesis is carried out as indicated in Example 1. Table 1: Amount of added CNSL Example 1* Example 2 ** Example 3 ** Example 4 ** CNSL (g) - 50 g 100 g 150 g P / F 1: 1,230 1: 1.203 1: 1.178 1: 1.153

• *: not according to the invention
• **: according to the invention

• *: nicht erfindungsgemäß
• **: erfindungsgemäß

The phenolic resins shown in Examples 1 to 4 were examined for their content of free phenol (gas chromatography) and free formaldehyde (titrimetric according to the hydroxylammonium chloride method). The values are listed in Table 2 and refer to the phenolic resin obtained. Table 2 also includes a value of "phenol (theor.)". This is calculated from the phenol content determined in Example 1 taking into account the dilution caused by the addition of CNSL. Table 2: Levels of free phenol and formaldehyde in the phenolic resin Ex. 1 * Ex. 2 ** Ex. 3 ** Ex. 4 ** Phenol (%) 14,30 12.90 11.40 9.80 Formaldehyde (%) 1.20 0.80 0.50 0.35 Phenol (theor.) (%) - 13.62 13,00 12.43

• *: not according to the invention
• **: according to the invention

The in Table 2 for The values indicated by the content of residual monomers show that the content of free phenol in the resins with increasing amount of added CNSL decreases. Although due to the decreasing molar ratio of Phenol: formaldehyde (P / F) an increase in the free phenol content would be expected it falls Decrease in phenol content even higher than that of the dilution effect (Phenol theor.) Would correspond.

Examples 5 to 8, Preparation and Testing of Molding mixtures

a) Preparation of the phenolic resin solutions

The phenolic resins obtained in Examples 1 to 4 are diluted as follows:
53.0% phenolic resin
7.8% isophorone
19.0% aromatic hydrocarbons; Solvesso ^® 100 (Exxon)
15.7% phthalate plasticizer
4.0% tall oil butyl ester; Forbiol ^® 102 (H); Arizona Chemicals
0.5% silane

b) Preparation of the polyisocyanate solution

As a polyisocyanate, a solution of 80% 4,4'-diphenylmethane diisocyanate (MDI technical) in 20% Solvesso ^® was 100.

c) Production and testing of the molding material mixtures

To 100 parts by weight of quartz sand H32 (Quarzwerke Frechen) are successively each 0.6 part by weight of phenol resin solution and 0.6 parts by weight of polyisocyanate solution and mixed intensively in a laboratory mixer. With this mixture test specimens (Georg Fischer bending VDG method according to instruction sheet P73) with the dimensions 22,36 × 22,36 × 220 mm produced by Fumigated with triethylamine (2 s at 2 bar pressure, then 10 s rinsing with Air) cured become.

The Bending strength of the specimens is with a device for testing the bending strength (Georg Fischer) immediately after their production and checked after 24 hours of storage.

• *: nicht erfindungsgemäß
• **: erfindungsgemäß

To determine the dimensional stability under thermal stress Georg Fischer bending bars with the dimensions 22.36 × 11.38 × 220 mm 10 minutes after their preparation for 30 minutes in a 150 ° C hot drying oven horizontally stored and in the middle with a 400 g loaded heavy train weight. After 30 minutes, the test bars are removed from the oven and stored without weight for 60 minutes at room temperature. Then the deflection is measured. The values determined are given in Table 3. Table 3: Flexural strength and dimensional stability of test bars example 5 * 6 ** 7 ** 8th** Phenolic resin (Ex.) 1 2 3 4 Flexural strength (N / cm ² ) immediately 160 165 150 145 after 24 h 430 410 420 390 Deflection (mm) 1.85 0.70 0.64 0.61

• *: not according to the invention
• **: according to the invention

The Test bars prepared with the phenolic resin of Examples 2 to 4 have sufficient strength. At temperature load bend the test bars prepared with the phenolic resin of Examples 2 to 4 less than that produced with the phenolic resin of Example 1 Test bars.

Examples 9 to 12: Use of CNSL as a reactive solvent

• *: nicht erfindungsgemäß
• **: erfindungsgemäß

From the phenolic resin obtained in Example 1, the phenolic resin solutions shown in Table 4 were prepared. For the phenolic resin solution used in Example 10, the CNSL was added at the expense of the phenolic resin. For the phenolic resin solutions used in Examples 11 and 12, the CNSL was added at the expense of the solvent. Table 4: Preparation of phenolic resin solutions example 9 * 10 ** 11 ** 12 ** phenolic resin 53,00 48,00 53,00 53,00 CNSL - 5.00 5.00 10.00 isophorone 7.80 7.80 6.96 6.12 Solvesso 100 (H) 19,00 19,00 16.96 14.91 phthalate 15.70 15.70 14.00 12.32 Forbiol 102 (H) 4.00 4.00 3.85 3.15 silane 0.50 0.50 0.50 0.50

• *: not according to the invention
• **: according to the invention

• *: nicht erfindungsgemäß
• **: erfindungsgemäß

From the phenolic resins prepared in Examples 9 to 12, test bars were prepared analogously to Examples 5 to 8 and examined for their bending strength and dimensional stability. The results are summarized in Table 5. Table 5: Flexural strength and dimensional stability of test bars example 9 * 10 * 11 * 12 ** Flexural strength (N / cm ² ) immediately 160 110 145 165 after 24 h 430 355 395 400 Deflection (mm) 1.85 1.75 1.55 1.35

• *: not according to the invention
• **: according to the invention

replaces If one part of the phenolic resin by CNSL (Example 10), so sink although the bending strengths. The thermal resistance of the test bar remains however.

replaces one part of the solvent mixture CNSL (Examples 11 and 12) improves the dimensional stability of the test bars under thermal stress.

Claims (16)

Molding material mixture for the production of moldings for the foundry industry, comprising at least: - a refractory molding material; and a polyurethane-based binder system comprising a polyisocyanate component and a polyol component, characterized in that the binder system contains at least a portion of cashew nut shell oil and / or at least one component of cashew nut shell oil and / or at least one derivative of cashew nut shell oil. Molding material mixture according to claim 1, characterized that the components or derivatives of cashew nutshell oil are selected from the group of cardol, cardanol and derivatives or oligomers of these connections. Molding material mixture according to claim 1 or 2 characterized characterized in that the cashew nut shell oil containing at least one component of cashew nutshell oil and / or the at least one derivative of cashew nut shell oil, at least forms a portion of the polyol component. Molding material mixture according to one of the preceding claims characterized characterized in that the cashew nut shell oil containing at least one component of cashew nutshell oil and / or the at least one derivative of cashew nut shell oil, at least forms a portion of the isocyanate component. Molding material mixture according to one of the preceding claims characterized characterized in that the polyol component by condensation of a phenolic component and an oxo component is formed, wherein the cashew nut shell oil, the at least one component of cashew nut shell oil and / or the at least one derivative of cashew nutshell oil contains at least a portion of the phenolic component forms. Molding material mixture according to one of the preceding claims characterized characterized in that the proportion of cashew nutshell oil, the at least one component of cashew nut shell oil and / or the at least one derivative of cashew nut shell oil on the phenolic component between 5 and 20 wt .-%, preferably between 0.5 and 15 wt .-% selected is. Molding material mixture according to one of the preceding claims characterized characterized in that the oxo component is formed by an aldehyde is. Molding material mixture according to one of the preceding claims characterized characterized in that the polyol component is a benzyl ether resin is formed. Molding material mixture according to one of the preceding claims characterized characterized in that the isocyanate component is an aliphatic, aromatic or heterocyclic isocyanate with at least two Isocyanate groups per molecule or its oligomers or polymers. Molding material mixture according to one of the preceding claims characterized in that the binder system in a proportion from 0.5 to 10% by weight, based on the weight of the refractory base molding material, is included. Molding material mixture according to one of the preceding claims characterized in that the binder system is a fatty acid ester as a solvent includes. Method of producing a molded article for the foundry industry, characterized by the steps: - Providing a molding material mixture according to one of the claims 1 to 11, - Forming the molding material mixture into a shaped body, - Curing of the molding by Addition of a curing catalyst. Method according to claim 12, characterized that the curing catalyst in gaseous Form is added. Method according to one of claims 12 or 13, characterized that curing is carried out essentially at room temperature. moldings for the Foundry industry, obtained by a method according to one the claims 12 to 14. Use of a shaped body according to claim 15 for metal casting.