Binders based on benzyl ether type phenolic resins containing free phenol and free hydroxybenzyl alcohol

Abstract

The present invention relates to a binder based on a benzyl ether-type phenolic resin and an isocyanate compound having at least two isocyanate groups, wherein the polyol component contains free phenol and free hydroxybenzyl alcohol. The present invention further relates to a molding material mixture containing the binder, and cores, molds or risers produced using the molding material mixture, as well as their use in metal casting.

Description

[Technical field]

[0001] The present invention relates to a binder based on a benzyl ether type phenolic resin and an isocyanate compound having at least two isocyanate groups for use in the cold box process for phenolic resins and polyurethanes (PUCB process) and / or the non-baking process for phenolic resins and polyurethanes (PUNB process), which contains free phenol and free hydroxybenzyl alcohol in a specific ratio to one another in the polyol component.The present invention further relates to molding material mixtures containing the binder, and to cores, moulds or risers produced with the molding material mixture, and to their use in metal casting. [Background technology]

[0002] The production of cores and moulds using the PUCB and / or PUNB process has acquired great importance in the foundry industry. Here, two-component polyurethane systems are used to bond the heat-resistant moulding base material. The polyol component consists of a polyol having at least two OH groups per molecule, and the isocyanate component consists of an isocyanate having at least two NCO groups per molecule. Among the polyol components, phenol-formaldehyde resins are used. The hardening of the mixture of moulding base material and binder, also called moulding material mixture for short, is carried out in the PUCB process with the aid of low-boiling tertiary amines, which pass through the moulding material mixture after moulding in gaseous form or as an aerosol (see US3409579). Usually, this is carried out with the aid of a carrier gas such as air, nitrogen or CO2, into which at least one tertiary amine is metered. In the PUNB process, the addition of liquid tertiary amines and / or metal compounds as catalysts to the moulding material mixture is carried out.

[0003] Traditional benzyl ether type phenolic resins made from phenol and formaldehyde as the sole phenolic base material (relative to pure phenolic resin without solvents and additives) typically have a residual phenol concentration (free phenol) of 4.0 to 18.0 weight percent and a free hydroxybenzyl alcohol concentration of 4.2 to 17.9 weight percent, with the concentration of free hydroxybenzyl alcohol always being lower than the concentration of free phenol. Hydroxybenzyl alcohols include o-hydroxybenzyl alcohol (saligenin), m-hydroxybenzyl alcohol and / or p-hydroxybenzyl alcohol (homosaligenin). When referring hereafter to the concentration of hydroxybenzyl alcohol (whether in the singular or plural), this refers to the sum of ortho-, meta- and para-hydroxybenzyl alcohols.

[0004] Traditional benzyl ether type phenolic resins (relative to pure phenolic resins without solvents and additives) made from phenol and o-cresol and formaldehyde as phenol-based materials typically have residual phenol concentrations of 3.0 to 12.0 weight percent, residual cresol concentrations of 2.0 to 6.0 weight percent, and hydroxybenzyl alcohol concentrations of 3.2 to 11.9 weight percent, with the concentration of hydroxybenzyl alcohol always being lower than that of phenol.

[0005] DE102015107016.2 teaches that the saligenin concentration of the exemplary benzyl ether type phenolic resin made from phenol and formaldehyde in the example of Table 1 is higher than the free phenol concentration. The weight ratio of phenol to saligenin or hydroxybenzyl alcohol, respectively, is always less than 1:1. US4205188 describes the selective production of saligenin from phenol and formaldehyde in an alkaline environment. A solution extraction process is applied with excess phenol to recapture the unconverted phenol. Summary of the Invention [Problem to be solved by the invention]

[0006] It is an object of the present invention to provide a binder based on a benzyl ether type phenolic resin that improves the strength and hot strength of sand cores produced with the binder. [Means for solving the problem]

[0007] This object can be solved by the subject matter of the independent claims. Advantageous developments are the subject matter of the dependent claims or are described below.

[0008] Thus, the subject of the present invention is to provide a binder containing a benzyl ether type phenolic resin with a certain phenol or hydroxybenzyl alcohol ratio and an isocyanate. Surprisingly, it has been found that delaying the addition of the monomer to the first addition step of the aromatic phenol ring with formaldehyde improves the strength and tendency to deformation. This is surprising, for example, because (catalytically active) hydroxybenzyl alcohol reacts with isocyanates, preferably via the -CH2OH group, which actually results in chain termination. This observation is surprising, because hydroxybenzyl alcohol is considered to be a chain terminator for the polyaddition reaction with diisocyanates, and in this connection lower strength and reduced hot strength are expected.

[0009] The present invention further relates to a molding material mixture containing a benzyl ether-type phenolic resin, a heat-resistant molding base material and a binder based on isocyanates, and optionally a catalyst, as well as cores, molds and risers produced from the molding material mixture after curing. The subject of the present invention is also the use of cores, molds and risers for metal casting, in particular for iron and aluminum casting. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] All commonly used phenolic compounds are suitable for making benzyl ether type phenolic resins. They can be used with unsubstituted phenols, substituted phenols or mixtures thereof. The phenolic compound is preferably unsubstituted at either both ortho positions or one of the ortho and para positions. The remaining carbon atoms of the ring can be substituted. The selection of the substituent is not particularly limited, so long as the substituent does not adversely affect the reaction of the phenol with the aldehyde.

[0011] Examples of substituted phenols are alkyl-, alkoxy-, aryl- and aryloxy-substituted phenols.

[0012] The basic structure of benzyl ether type phenolic resins has phenolic units linked with -CH- as well as -CH-O-CH- and can be represented as the following example (for products incorporating only formaldehyde):

[0013] [ka]

[0014] The variable units are typically statistically distributed (i.e., linked in sequences other than those shown above). The phenolic units may also have some para linkages, where in each case R 1 are independently hydrogen (particularly m and n), or a C1-C26 alkyl substituent (saturated or unsaturated, linear or branched) of the phenol in the ortho, meta or para position relative to the phenolic hydroxy group; the sum of m and n is at least 2 and the ratio of m:n is at least 1; R is independently hydrogen, -CH2OH or -CH2O-R 2 (R 2 R = C1 to C9 hydrocarbons. 2 The groups can be linear or branched, saturated or unsaturated.

[0015] The aforementioned substituents have, for example, 1 to 26 carbon atoms, preferably 1 to 15 carbon atoms. Examples of suitable phenols are o-cresol, m-cresol, p-cresol, 3,5-xylenol, 3,4-xylenol, 3,4,5-trimethylphenol, 3-ethylphenol, 3,5-diethylphenol, p-butylphenol, 3,5-dibutylphenol, p-amylphenol, cyclohexylphenol, p-octylphenol, p-nonylphenol, cardanol, 3,5-dicyclohexylphenol, p-crotylphenol, p-phenylphenol, 3,5-dimethoxyphenol and p-phenoxyphenol.

[0016] Phenol itself is particularly preferred. Even more highly condensed phenols are suitable, such as bisphenol A. Also suitable are polyfunctional phenols, i.e., those having two or more phenolic hydroxyl groups.

[0017] Preferred polyfunctional phenols have 2 to 4 phenolic hydroxyl groups. Specific examples of suitable polyfunctional phenols are pyrocatechol, resorcinol, hydroquinone, pyrogallol, phloroglucinol, 2,5-dimethylresorcinol, 4,5-dimethylresorcinol, 5-methylresorcinol, cardol or 5-ethylresorcinol. Mixtures of various mono- and polyfunctional, and / or substituted and / or condensed phenolic components can also be used to make the polyol component.

[0018] In one embodiment, a phenol of general formula I

[0019] [ka] is used to make the phenol formaldehyde resin component, where A, B and C are each independently selected from a hydrogen atom, a branched or unbranched alkyl or alkenyl moiety, e.g., a branched or unbranched alkoxy moiety, which may have 1 to 26, preferably 1 to 15 carbon atoms, a branched or unbranched alkenoxy moiety, which may have 1 to 26, preferably 1 to 15 carbon atoms, and an aryl or alkylaryl moiety, such as bisphenyl.

[0020] Along with formaldehyde, aldehydes having the following formula are also suitable as further aldehydes for making benzyl ether type phenolic resins:

[0021] (3) R-CHO (wherein R is a carbon atom moiety having 1 to 3 carbon atoms, preferably 1 carbon atom). Particular examples are acetaldehyde and propionaldehyde. Formaldehyde is particularly preferably used in its liquid form, either as paraformaldehyde or trioxane.

[0022] To obtain a benzyl ether type phenolic resin, it is preferable to use at least an equal molar amount of the aldehyde compound to the molar amount of the phenolic compound. Preferably, the molar ratio of the aldehyde compound to the phenolic compound is 1.05:1.0 to 2.5:1, particularly preferably 1.1:1 to 2.2:1, and most preferably 1.2:1 to 2.0:1.

[0023] According to EP 0 177 871 A2, aliphatic monoalcohols having 1 to 8 carbon atoms can be added as further reactants. The alkoxylation is intended to give the phenol-formaldehyde resins higher thermal stability and a longer sand service life.

[0024] The preparation of benzyl ether type phenolic resins is carried out according to methods known to experts. Here, phenol and aldehyde are converted in the presence of divalent metal ions, preferably at a temperature below 130°C. The water formed is distilled off. A suitable entrainer such as toluene or xylene can be added to the reaction mixture for this purpose, or the distillation is carried out under reduced pressure.

[0025] Suitable catalysts for producing benzyl ether type phenolic resins are salts of divalent ions of metals such as Mn, Zn, Cd, Mg, Co, Ni, Fe, Pb, Ca and Ba, especially Zn salts. Zinc acetate is preferably used. The amount used is not critical. The typical amount of metal catalyst is 0.02-0.3 weight percent, preferably 0.02-0.18 weight percent, based on the total amount of phenolic compounds and aldehyde compounds.

[0026] Such resins are described, for example, in US 3,485,797 and EP 1,137,500 B1, the disclosures of which are hereby expressly incorporated by reference, both with respect to the benzyl ether type phenolic resins themselves and their preparation. Analysis of these resins shows that the weight ratio of free phenol (hydroxybenzene) to free hydroxybenzyl alcohol is always less than 1:1.

[0027] The first reaction step of formaldehyde addition, consisting of one mole of phenol and one mole of formaldehyde, forms hydroxybenzyl alcohols, specifically saligenins. Due to the direct effect of the ortho-ortho metal catalyst,

[0028] [ka] However,

[0029] [ka] is also possible. Since the -CH2-OH groups can be attached at the ortho and ortho positions, ortho and para positions, and ortho, ortho and para positions, mixtures of positional isomers are also possible. In a further embodiment, one, two or three -CH2-OH groups can be esterified with a C1-C9 monoalcohol. The monoalcohol can be linear or branched, saturated or unsaturated.

[0030] The reference to the example of phenol also applies to the phenol-based materials o-cresol and m-cresol. The possible mixtures of positional isomers for the -CH2-OH group are ortho or para, and ortho and para. In further embodiments, one or two -CH2-OH groups can be esterified with a C1-C9 monoalcohol. The monoalcohol can be linear or branched, saturated or unsaturated.

[0031] When cardanol and / or cardol are used as the phenolic based material, the -CH2-OH groups can be attached at the ortho and ortho positions, the ortho and para positions, and the ortho, ortho and para positions. In further embodiments, one, two or three -CH2-OH groups can be esterified with a C1-C9 monoalcohol.

[0032] The monoalcohol may be linear or branched, saturated or unsaturated.

[0033] Surprisingly, it has now been found that a ratio of free hydroxybenzyl alcohol to free phenol in a benzyl ether type phenolic resin greater than 1, and in particular a ratio of greater than 1.1, improves the strength and hot strength of sand cores produced therewith.

[0034] The monomeric addition products are defined as the first reaction step of a phenol-based material with formaldehyde, in which up to three hydrogens on the ring of the phenol-based material may be replaced by -CH2-OH groups. The phenol-based monomeric addition products have molar masses of 124 g / mol (hydroxybenzyl alcohol) to 184 g / mol (phenol + up to three -CH2OH). Any C1-C26 alkyl groups attached to the phenol-based material and / or attached as alkenyl groups on the esterified -CH2-OH groups are not included in the given molar weights.

[0035] Preferably, the weight ratio of phenol to hydroxybenzyl alcohol used is greater than 1:1.2 and is 1:30, more preferably 1:1.3 to 1:20, particularly preferably 1:1.6 to 1:15, and most preferably 1:1.8 to 1:13.

[0036] Preferably, the weight ratio of phenol to saligenin (o-hydroxybenzyl alcohol) used is greater than 1:1.1 to 1:25, more preferably 1:1.2 to 1:15, particularly preferably 1:1.5 to 1:10, and most preferably 1:1.8 to 1:8.

[0037] In particular, the weight of benzyl ether type phenolic resin refers to the sum of the weights of phenolic resin and associated (free) monomers, where the phenolic resin is the conversion product of at least one formaldehyde compound and one phenolic compound, including polymer-like conversion products such as end group alkoxylation.

[0038] The concentration of free phenol relative to the weight of the benzyl ether type phenolic resin is preferably less than 3 weight percent, in particular less than 2.5 weight percent, and even more preferably less than 2 weight percent.

[0039] As a result, the concentration of saligenin (o-hydroxybenzyl alcohol) is, for example, 2 to 16 weight percent, or 1 to 8 weight percent, and the concentration of hydroxybenzyl alcohol is, for example, 2 to 26 weight percent, or 1 to 13 weight percent, in each case relative to the weight of the benzyl ether type phenolic resin.

[0040] The benzyl ether type phenolic resin can contain the required concentration of free hydroxybenzyl alcohol, particularly free saligenin, either by control during or after the reaction to form the benzyl ether type phenolic resin, or by addition of hydroxybenzyl alcohol, particularly saligenin, before, after or during, particularly after, the reaction to form the phenolic resin.

[0041] It is also possible to control the ratio of free phenol and hydroxybenzyl alcohol, in particular saligenin, in the benzyl ether type phenolic resin by subsequent removal of free phenol (preferably free phenol) from the benzyl ether type phenolic resin, for example by steam distillation, azeotropic distillation or leaching with water according to DIN 53704 and, for example, filtration. If desired, the addition of hydroxybenzyl alcohol, in particular saligenin, can also be carried out after this step.

[0042] The molar mass of the benzyl ether type phenolic resin without phenol and without monomer condensation products (HPLC Agilent 11100, RI detector, PSS SDV 5 μm precolumn, PSS SDV 5 μm column 1000 Å, PSS SDV 5 μm column 100 Å THF flow medium, column temperature 35° C., calibrated against PSS polystyrene ReadyCal Kit[low] (Mp266-67500D), internal standard PSS polystyrene ReadyCal Kit[low] (Mp266-67500D)) is preferably between 500 and 1100 g / mol, particularly preferably between 550 and 1000 g / mol, most preferably between 560 and 980 g / mol.

[0043] Hydroxyl numbers (determined according to DIN 53240) between 500 and 900 mg KOH / g, particularly preferably between 550 and 850 mg KOH / g, most preferably between 560 and 750 mg KOH / g, are used for further characterization of the benzyl ether type phenolic resins.

[0044] The isocyanate component of the binder system preferably comprises an aliphatic, cycloaliphatic or aromatic monomeric or polymeric isocyanate having an average of 2 to 5 isocyanate groups per molecule.

[0045] Mixtures of isocyanates may also be used depending on the properties desired.

[0046] Suitable isocyanates include aliphatic isocyanates such as hexamethylene diisocyanate, cycloaliphatic isocyanates such as 4,4'-dicyclohexylmethane diisocyanate and their dimethyl derivatives. Examples of suitable aromatic isocyanates are toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate, xylene diisocyanate and their methyl derivatives, and polymethylene polyphenyl isocyanate. Preferred isocyanates are aromatic isocyanates, and polymethylene polyphenyl polyisocyanates such as industrial 4,4'-diphenylmethane diisocyanate, i.e., 4,4'-diphenylmethane diisocyanate with some isomers and higher homologs, are particularly preferred.

[0047] Isocyanates can also be derivatized by converting isocyanates capable of forming bonds with each other such that some of these isocyanate groups are derivatized to form biuret, allophanate, uretidione or carbodiimide groups. For example, the uretidione groups of dimerization products such as MDI or TDI are of interest. However, preferably such derivatized isocyanates are used only as a component along with the non-derivatized isocyanates described above.

[0048] Preferably, the isocyanate is used in an amount such that the number of isocyanate groups is 80 to 120% of the number of free hydroxyl groups of the resin.

[0049] The isocyanate component of the binder system is preferably used as a solution in an organic solvent or a combination of organic solvents. Thus, a solvent may be necessary, for example, to maintain the components of the binder in a sufficiently low viscosity state. This is necessary, among other things, to obtain uniform crosslinking of the heat-resistant molding material and to maintain its free-flowing properties.

[0050] Each polyol or isocyanate component of the binder system is preferably used as a solution in an organic solvent or a combination of organic solvents. Thus, a solvent may be necessary, for example, to maintain the components of the binder in a sufficiently low viscosity state. This is necessary, among other things, to obtain uniform crosslinking of the heat-resistant molding material and to maintain its free-flowing properties.

[0051] Known aromatic solvents, such as those called naphtha, can be used as solvents for the polyol component. Starting from benzene, alkyl and / or alkenyl groups are substituted, independently of one another, on the aromatic ring, which have a chain length of C1 to C30, preferably C1 to C20, particularly preferably C1 to C16. Independently of one another, 1 to 6 hydrogen atoms of the benzene ring can be replaced by alkyl and / or alkenyl groups, preferably 1 to 4, particularly preferably 1 to 3 hydrogen atoms of the benzene ring. Regardless of this, the alkyl or alkenyl chain can be linear or branched.

[0052] Furthermore, oxygen-rich organic solvents can be used.Dicarboxylic acid esters, glycol ether esters, glycol diesters, glycol diethers, cyclic ketones, cyclic esters (lactones), cyclic carbonates or silicic acid esters, or mixtures thereof are particularly suitable.Dicarboxylic acid esters, cyclic ketones, silicic acid esters and cyclic carbonates are preferably used.

[0053] Typical dicarboxylic acid esters have the formula R1OOC-R2-COOR1, where the R1 groups are in each case independently of one another (especially of the second R1) an alkyl group having 1 to 12, preferably 1 to 6, carbon atoms and R2 is a linear or branched hydrocarbon group having 1 to 7 carbon atoms. Examples are the dimethyl esters of carboxylic acids having 4 to 6 carbon atoms, which are available, for example, from Dupont under the name "Dibasic Esters".

[0054] Typical glycol ether esters are compounds having the formula R3-O-R4-OOCR5, where R3 is an alkyl group having 1 to 4 carbon atoms, R4 is a hydrocarbon group having 2 to 4 carbon atoms, and R5 is an alkyl group having 1 to 3 carbon atoms, such as butyl glycol acetate, with glycol ether acetate being preferred.

[0055] Typical glycol diesters correspondingly have the general formula R3COO-R4-OOCR5, where R3 to R5 are as defined above and these radicals are selected independently of one another in each case, such as propylene glycol diacetate. Glycol diacetates are preferred. Glycol diethers can be characterized by the formula R3-O-R4-O-R5, where R3 to R5 are as defined above and these radicals are selected independently of one another in each case, such as dipropylene glycol dimethyl ether.

[0056] Typical cyclic ketones, cyclic esters and cyclic carbonates having 4 to 5 carbon atoms are also suitable (such as propylene carbonate). The carbons may be linked in a branched or unbranched fashion and may be saturated or unsaturated.

[0057] Also suitable are fatty acid esters -R6-OOCR7- (wherein R7 is a C8-C32 hydrocarbon and R6 is a C1-C9, especially C1-C4, hydrocarbon), such as rapeseed oil fatty acid methyl esters, oleic acid butyl esters and isopropyl esters of various fatty acids.

[0058] Silicic acid esters are also suitable in their monomeric form or as oligomers, as known from WO 2009 / 130335 A2. Suitable alkyl / alkoxysilanes or alkyl / alkoxysiloxanes are, for example, esters of orthosilicic acid, in which one, two or three alcohol groups are replaced by a substituted or unsubstituted hydrocarbon moiety, of the formula R 1 n Si(OR) 4-n where n=1, 2 or 3, and each R group, independently of any further R groups, represents an organic group, preferably a branched or unbranched C1-C30 alkyl or aryl, as correspondingly defined in conjunction with the first aspect. 1 is a substituted or unsubstituted, branched or unbranched hydrocarbon group, R 1 The groups are the same or different when n=2 or 3.1 The group is preferably a substituted or unsubstituted, branched or unbranched C1-C30 alkyl or a substituted or unsubstituted aryl, and particularly preferably a substituted or unsubstituted, branched or unbranched C1-C6 alkyl or a substituted or unsubstituted C6-C10 aryl. Unsubstituted, branched or unbranched C1-C6 alkyl or unsubstituted phenyl is most preferred. Here, methyl, ethyl and propyl are likewise particularly preferred.

[0059] The modified esters are preferred and are selected from the group consisting of tetraalkoxysilanes, monoalkyltrialkoxysilanes, dialkyldialkoxysilanes, trialkylmonoalkoxysilanes, monoaryltrialkoxysilanes, diaryldialkoxysilanes and triarylmonoalkoxysilanes, where the alkyl or alkoxy groups are preferably C1-C6 alkyl groups.

[0060] It is preferable that the modified ester is selected from the group consisting of methyltrimethoxysilane, methyltriethoxysilane, methyltripoxysilane, methyltributoxysilane, ethyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, isopropyltrimethoxysilane, isopropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3,4-epoxycyclohexyltrimethoxysilane, dimethoxydimethylsilane, diethoxydimethylsilane, diethyldimethoxysilane and diethyldiethoxysilane.

[0061] Particular preference is given to tetraethyl orthosilicate, tetrapropyl orthosilicate, mixtures thereof, and oligomers or mixtures of oligomers thereof. Particular preference is given to tetraethyl orthosilicate and tetrapropyl orthosilicate, or mixtures thereof.

[0062] Aromatic solvents, any of the aforementioned polar solvents or mixtures thereof are used as solvents for the isocyanates. Fatty acid esters and silicate esters are also suitable.

[0063] The proportion of the solvent in the binder may be comprised between 2 and 57 percent by weight, in particular between 3 and 53 percent by weight.

[0064] Alongside the components already mentioned, the binder system can contain further additives such as silanes (for example according to EP 1 137 500 B1), internal release agents such as fatty alcohols (for example according to US 4,602,069), drying oils (for example according to US 4,268,425), complexing agents (for example according to US 5,447,968) and additives for extending the processing time (for example according to US 4,540,724), flow improvers of the silicone surfactant type, or mixtures thereof.

[0065] Conventional and known materials and mixtures thereof for producing casting molds can be used as heat-resistant molding base materials (hereinafter also referred to briefly as "molding base materials"). Examples of suitable materials are silica sand, zircon sand, chrome ore sand, olivine, vermiculite, bauxite, fireclay, and so-called artificial molding base materials, i.e. molding base materials that are formed into a spherical or approximately spherical shape (such as an ellipsoid) by industrial molding processes.

[0066] Examples of this are glass beads, glass granules, or artificial spherical ceramic sand, the so-called Cerabeads®, but also Spherichrome®, SpherOX® or "Carboaccucast", as well as hollow microspheres, such as aluminum silicate hollow spheres (microspheres), which can be separated among other things as components of fly ash. Mixtures of the mentioned refractory materials are also possible.

[0067] Particularly preferred is a heat-resistant material containing more than 50 weight percent of silica sand relative to the molding base material. Heat-resistant molding base material is understood to have a high melting point (melting temperature). Preferably, the melting point of the heat-resistant molding base material is more than 600°C, more preferably more than 900°C, particularly preferably more than 1200°C, and most preferably more than 1500°C.

[0068] The heat-resistant molding base material preferably constitutes more than 80 percent by weight, in particular more than 90 percent by weight, particularly preferably more than 95 percent by weight, of the molding material mixture.

[0069] The average diameter of the heat-resistant molding base material is generally in the range between 100 μm and 600 μm, preferably between 120 μm and 550 μm, particularly preferably between 150 μm and 500 μm. The particle size can be determined, for example, by sieving according to DIN ISO 3310. Particularly preferred are particle shapes having a ratio of the length of minimum extension to the length of maximum extension (at right angles to one another and in any case relative to all spatial directions) of 1:1 to 1:5 or 1:1 to 1:3, i.e., not fibrous, for example.

[0070] The heat-resistant molding base material is preferably in a free-flowing state, in particular to enable processing of the molding material mixture of the invention in conventional core shooters.

[0071] Tertiary amines are suitable catalysts. For the PUCB process, volatile tertiary amines such as trimethylamine ("TMA", CAS RN 75-50-3), dimethylethylamine ("DMEA", CAS 75-64-9), dimethyl-n-propylamine ("DMPA", CAS RN 926-63-6), dimethylisopropylamine ("DMIPA", CAS 996-35-0), diethylmethylamine (DEMA), triethylamine ("TEA", CAS RN 121-44-8), tri-n-propylamine, triisopropylamine, tri-n-butylamine and triisobutylamine are used.

[0072] Liquid tertiary amines are used for the PUNB process. At room temperature (25°C), this includes liquid tertiary amines and those that become liquid after heating, for example to 40°C, or that dissolve in a suitable solvent. Examples are tris-(3-dimethylamino)propylamine and 4-(C1-C4 alkyl)pyridines such as isoquinoline. Arylpyridines such as phenylpyridine, pyridine, acridine, 2-methoxypyridine, pyridazine, 3-chloropyridine, quinoline, N-methylimidazole, N-ethylimidazole, 4,4'-dipyridine, 4-phenylpropylpyridine, 1-methylbenzimidazole, and 1,4-thiazine.

[0073] Furthermore, the present invention relates to a method for producing a pharmaceutical composition comprising the steps of: (a) mixing a heat-resistant molding base material with the binder of the invention in an amount of 0.2 to 12 percent by weight, preferably 0.3 to 13 percent by weight, particularly preferably 0.4 to 12 percent by weight, based on the amount of heat-resistant molding base material, and a catalyst, which is added simultaneously (in the PUNB process) or separately at a later time (in the PUCB process), to obtain a molding material mixture, (b) placing the molding material mixture obtained in step (a) into a mold; (c) optionally adding a separate catalyst (PUCB) to harden the molding material mixture in the mold using the catalyst of the present invention to obtain a core or casting mold; and (d) Thereafter, the core or mold is separated from the mold and, optionally, further cured. The present invention relates to a method for producing a molding material mixture, comprising:

[0074] To prepare the molding material mixture, the components of the binder system can be mixed first and then added to the heat-resistant molding base material. However, it is also possible to add the components of the binder simultaneously or one after the other in any order to the heat-resistant molding base material.

[0075] Conventional methods can be used to obtain a homogeneous mixture of the components of the molding material mixture. The molding material mixture can also contain other conventional components such as iron oxide, crushed flax fiber, sawdust granules, pitch, silicone surfactant type flow improvers and refractory metals.

[0076] According to the present invention, curing can take place by the PUCB or PUNB process. In the case of the PUCB process, for curing, a low-boiling tertiary amine is passed in the form of a gas or as an aerosol through the molded molding material mixture using an inert carrier gas. There is no addition of a separate catalyst. All known cold box amine catalysts can be used.

[0077] In the case of the PUCB process, the amine or metal catalyst can be already dissolved in the binder or can be mixed with the heat-resistant material as a separate component, with the amount added ranging from about 0.1 weight percent to about 5 weight percent based on the molding material mixture.

[0078] The molded bodies produced by this method can have any conventional shape used in casting. In one preferred embodiment, the molded bodies are in the form of casting molds, cores or risers. These are distinguished by their high mechanical stability.

[0079] The invention further relates to the use of this compact for metal casting, in particular for iron and aluminum casting.

[0080] The present invention will be explained in more detail below based on preferred embodiments or respective experimental examples, which are not intended to limit the present invention.

[0081] Experimental Example Ingredients used All percentage information is by weight.

[0082] Benzyl ether type phenolic resin (o-cresol / phenol / cardanol copolymer), which is characterized by the following analytical values: Molecular weight (Mw) approximately 900 MW g / mol, hydroxyl number approximately 560 mg KOH / g, free phenol concentration 1.8%, saligenin concentration 3.8%.

[0083] ECOCURE 370 / 5 PART 1 - Benzyl ether type phenolic resin, partially esterified with n-butanol, supplied by ASK-Chemicals GmbH, free phenol content 4.5%, saligenin content 3.8% Isocyanate component: homogeneous mixture of 80% Lupranat M 20 S and 20% RME KATALYSATOR 706 - Dimethylpropylamine, supplied by ASK-Chemicals GmbH Silica sand H 32 - supplied by Quarzwerke GmbH MIRATEC DC 3 - Aqueous laminar flow, flow time 12 seconds / 4mm cup, supplied by ASK-Chemicals GmbH LUPRANAT M 20 S: High molecular weight MDI, functionality 2.6, supplied by BASF SE DBE - Mixture of dimethyl esters of C4-C6 dicarboxylic acids, supplied by Dupont RME - Distilled Rapeseed Oil Fatty Acid Methyl Esters, supplied by Cargill Silane 2201 EQ - Ureidosilane in 50% methanol, supplied by Evonik Industries Phenol - supplied by Sigma Aldrich o-Hydroxybenzyl alcohol - supplied by Sigma Aldrich p-Hydroxybenzyl alcohol - supplied by Sigma Aldrich

[0084] Measurement of phenol and saligenin concentrations Phenol and saligenin concentrations were determined by gas chromatography as described below.

[0085] How to explain: Calibration: Internal standard method, 7-point calibration for each substance to be determined Internal standard: 2,4,6-trimethylphenol PA Standards: Phenol PA and Saligenin (o-hydroxybenzyl alcohol) PA Gas chromatograph: Agilent 7890Plus with FID, capillary column, autosampler and Agilent ChemStation Equipment parameters: Intake system: split / splitless injector, split 50:1 after 2 minutes (79.9 l / min), runtime 20 ml / min, temperature: 280°C Carrier gas: Hydrogen 5.0, flow rate 1 ml / min, constant flow method Capillary column: HP-5MS, HP 19091S-105, length 50 m, diameter 0.2 mm, film 0.33 μm Temperature program: 60° C. for 1.5 min, 4.0° C. / min to 140° C., hold for zero min, then 20° C. / min to 325° C., hold for 6 min at 325° C. Detector: FID, Temperature: 320℃, Combustible gas: Hydrogen 5.0 at 20ml / min, Synthetic air 5.0 at 350ml / min, Make-up gas: Nitrogen 5.0 at 25ml / min Autosampler: 10 μl GC syringe, 1 μl injection, fast injection mode Quantification: Agilent Chemstation standard settings, internal standard method, results are weight percent

[0086] [Table 1] Table 1 shows polyol compositions made based on benzyl ether type phenolic resins; the numerical information represents weight percent.

[0087] [Table 2] Table 2 shows the polyol components made based on ECOCURE 370 / 5 PART 1; the numerical information represents weight percent.

[0088] Strength (N / cm 2 ) Measurement In a Hobart mixer, a sand mixture consisting of quartz sand H32 with 0.60% of the above-mentioned binder composition (in each case individually for Examples A1 to B11) and 0.60% of the isocyanate component was mixed for 2 minutes until homogenous.

[0089] The sand mixture was transferred to a Roeper H1 core shooter and in each case two cores with dimensions (l x w x h) of 220 mm x 22.4 mm x 22.4 mm were placed in the mould using compressed air at a closing pressure of 4 bar. The sand was hardened using CATALYST 706 (0.5 ml, 10 s gassing time at 2 bar purging pressure). After hardening the cores were removed and the strength was determined using a Multiserw bending apparatus after 15 or 30 seconds, respectively.

[0090] To determine hot strength, 10 minute old cores were immersed in MIRATEC DC3 flow for 4 seconds and dried in a circulating air dryer for 30 minutes at 150° C. After 30 minutes at 150° C. the cores were removed and while still hot the flexural strength was immediately tested in a Multiserw unit.

[0091] [Table 3] Table 3 shows N / cm 2 The bending strength measured at .times.

[0092] [Table 4] Table 4 shows the strength in N / cm using ECOCURE 370 / 5 PART1 as an example. 2 The bending strength measured at .times. Both tables show results indicating that the addition of o-hydroxybenzyl alcohol or p-hydroxybenzyl alcohol increases the quick and hot strength. Approximately the same ratio of free phenol to free saligenin (A1 and A2, respectively) shows lower quick and hot strength.

Claims

1. A binder for curing a molding material mixture, said binder comprising: - a polyol component which is a benzyl ether type phenolic resin; - an isocyanate component consisting of one or more isocyanate compounds having at least two isocyanate groups per molecule; At least In each case, based on the weight of the benzyl ether type phenolic resin, - said binder contains less than 3 percent by weight of phenol; the saligenin content of said binder is between 1 and 16 percent by weight; the hydroxybenzyl alcohol content of said binder is between 1 and 26 percent by weight; The binder has the following characteristics: a) the binder contains phenol and hydroxybenzyl alcohol, and the weight ratio of phenol to hydroxybenzyl alcohol is greater than 1:1.2; b) the binder contains phenol and saligenin (o-hydroxybenzyl alcohol), and the weight ratio of phenol to saligenin is greater than 1:1.1; The binder may be further characterized by one or both of the following:

2. 2. The binder of claim 1, wherein the weight ratio of phenol to hydroxybenzyl alcohol is greater than 1:1.2 to 1:

30.

3. 3. The binder according to claim 1 or 2, wherein the weight ratio of phenol to hydroxybenzyl alcohol is from 1:1.8 to 1:

13.

4. 4. The binder according to claim 1, wherein the weight ratio of phenol to saligenin is greater than 1:1.1 and is 1:

25.

5. A binder according to any one of claims 1 to 4, wherein the weight ratio of phenol to saligenin is from 1:1.5 to 1:

10.

6. A binder according to any one of claims 1 to 5, wherein the weight ratio of phenol to saligenin is from 1:1.8 to 1:

8.

7. 7. The binder of claim 1, wherein the benzyl ether type phenolic resin contains less than 2.5 percent by weight of phenol, based on the weight of the benzyl ether type phenolic resin.

8. 8. The binder of claim 1, wherein the benzyl ether type phenolic resin contains less than 2 weight percent phenol, based on the weight of the benzyl ether type phenolic resin.

9. The binder according to any one of claims 1 to 8, wherein the benzyl ether type phenolic resin further contains one or more of cresol, cardanol, and cardol.

10. 10. The binder according to claim 1, wherein the benzyl ether type phenolic resin has a hydroxyl number according to DIN 53240 of 500 to 900 mg KOH / g.

11. 11. The binder according to claim 1, wherein the benzyl ether type phenolic resin has a hydroxyl number according to DIN 53240 of 560 to 750 mg KOH / g.

12. 12. The binder according to claim 1, wherein the benzyl ether type phenolic resin has an average molecular weight of 500 to 1100 g / mol, calculated as weight average, obtained from DIN 55672-1 using GPC without taking into account phenol and monomer addition products.

13. 13. The binder according to claim 1, wherein the benzyl ether type phenolic resin has an average molecular weight of 560 to 980 g / mol, calculated as weight average, obtained from DIN 55672-1 using GPC without taking into account phenol and monomer addition products.

14. The binder according to any one of claims 1 to 13, comprising a solvent, said solvent for the polyol component comprising a dicarboxylic acid ester and / or a fatty acid ester.

15. 15. The binder of claim 14 containing less than 10 weight percent aromatic solvent.

16. The binders, independently of one another, - 8 to 70 percent by weight of said benzyl ether type phenolic resin, - 13 to 78 percent by weight of said isocyanate compound, and - 2 to 57 weight percent of a solvent for said benzyl ether type phenolic resin and said isocyanate compound. The binder according to any one of claims 1 to 15, comprising:

17. The binders, independently of one another, - 10 to 62 percent by weight of said benzyl ether type phenolic resin, - 17 to 70 percent by weight of said isocyanate compound, and - 3 to 53 weight percent of a solvent for said benzyl ether type phenolic resin and said isocyanate compound. The binder according to any one of claims 1 to 16, comprising:

18. A molding material mixture comprising a binder according to any one of claims 1 to 17 and a heat-resistant molding base material, The molding material mixture, wherein the heat-resistant molding base material is selected from one or more members of the group consisting of olivine, fireclay, bauxite, aluminum silicate hollow spheres, glass beads, glass granules, synthetic ceramic molding base materials, and silicon dioxide.

19. A molding material mixture comprising a binder according to any one of claims 1 to 17 and a heat-resistant molding base material, A molding material mixture, wherein the heat-resistant molding base material is selected from one or more members of the group: silica sand, zircon sand, or chrome ore sand.

20. A method for producing a molded body as a casting mold or core, comprising the steps of: (i) the production of a molding material mixture according to claim 18 or 19, (ii) introducing the molding material mixture or its components into a mold; (iii) curing the molding material mixture in the mold with at least one tertiary amine to obtain a self-supporting molding; and (iv) Thereafter, the hardened molded body is separated from the mold and, optionally, further hardened to obtain a hardened molded body. A method comprising:

21. 21. The method according to claim 20, wherein the binder is used as a kit consisting of at least one isocyanate compound as one component and at least one benzyl ether-type phenolic resin as a further component, which are separate from one another, for producing the molding material mixture.

22. The tertiary amine is selected from the group consisting of trimethylamine (TMA), dimethylethylamine (DMEA), dimethyl-n-propylamine (DMPA), dimethylisopropylamine (DMIPA), diethylmethylamine (DEMA), triethylamine (TEA), tri-n-propylamine, triisopropylamine, tri-n-butylamine, triisobutylamine, 4-(C １ ~C ４ 22. The method of claim 20 or 21, wherein the arylpyridine is selected from one or more members of the group consisting of N,N-bis[3-(dimethylamino)propyl]-N',N'-dimethylpropane-1,3-diamine, isoquinoline, arylpyridines such as phenylpyridine, pyridine, acridine, 2-methoxypyridine, pyridazine, 3-chloropyridine, quinoline, N-methylimidazole, N-ethylimidazole, 4,4'-dipyridine, 4-phenylpropylpyridine, and 1-methylbenzimidazole.

23. of a binder for hardening the molding material mixture, or - for producing a molding compound mixture consisting of said binder and a heat-resistant molding base material Manufacturing kits, each separate from the other comprising at least one isocyanate component and one phenolic resin component; the isocyanate component comprises one or more isocyanate compounds having at least two isocyanate groups per molecule; the phenolic resin component contains a benzyl ether type phenolic resin, In each case, based on the weight of the benzyl ether type phenolic resin, - said binder contains less than 3 percent by weight of phenol; the saligenin content of said binder is between 1 and 16 percent by weight; the hydroxybenzyl alcohol content of said binder is between 1 and 26 percent by weight; The binder has the following characteristics: a) the binder contains phenol and hydroxybenzyl alcohol, and the weight ratio of phenol to hydroxybenzyl alcohol is greater than 1:1.2; b) the binder contains phenol and saligenin (o-hydroxybenzyl alcohol), and the weight ratio of phenol to saligenin is greater than 1:1.1; The kit may further be characterized by one or both of the following:

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