Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
  • B22C1/16—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents
  • B22C1/20—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of organic agents
  • B22C1/22—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of organic agents of resins or rosins
  • B22C1/2233—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of organic agents of resins or rosins obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • B22C1/224—Furan polymers

Definitions

• the present invention relates primarily to a mixture suitable for use in the no-bake process for the production of cores and molds for the foundry industry, and to a reaction mixture comprising such a mixture and an acid hardener (i.e., a catalyst acid). Furthermore, the present invention relates to a method for producing a mixture according to the invention and to a method for producing a casting mold or a core. The invention also relates to a casting mold or a core for producing metal bodies and to a kit comprising a mixture according to the invention and certain acid hardeners. In addition, the invention relates to the use of a mixture according to the invention as cold curing binder and the use of such mixtures or reaction mixtures in a no-bake process for the production of metal bodies. Further aspects of the present invention will become apparent from the description, the embodiments and the claims.
• the melt liquefied materials, ferrous metals or non-ferrous metals are converted into shaped objects with specific workpiece properties.
• the casting molds are divided into lost molds that are destroyed after each casting, and permanent molds, with each of which a large number of castings can be produced.
• the Lost forms usually consist of a refractory, granular molding material, which is solidified with the aid of a hardenable binder.
• Shapes are negatives, they contain the emptying cavity, which results in the casting to be produced.
• the inner contours of the future casting are formed by cores. In the manufacture of the mold, the cavity is shaped into the molding material by means of a model of the casting to be manufactured. Inner contours are represented by cores formed in a separate core box.
• both organic and inorganic binders can be used, the curing of which can be effected by cold or hot processes.
• Cold processes are processes in which the curing takes place essentially at room temperature without heating the molding material mixture.
• the curing is usually carried out by a chemical reaction, which can be triggered, for example, by passing a gaseous catalyst through the molding material mixture to be cured, or by adding a liquid catalyst to the molding material mixture.
• hot processes the molding material mixture is heated to a sufficiently high temperature after molding to drive off, for example, the solvent contained in the binder, or to initiate a chemical reaction by which the binder is cured by crosslinking.
• the production of the casting molds can be carried out in such a way that the molding material is first mixed with the binder, so that the grains of the refractory molding material are coated with a thin film of the binder.
• the molding material mixture obtained from molding material and binder can then be introduced into a corresponding mold and optionally compacted in order to achieve a sufficient stability of the casting mold.
• the mold is cured, for example by heating it or by adding a catalyst which effects a curing reaction. If the mold has reached at least a certain initial strength, it can be removed from the mold.
• molds for the production of metal bodies are often composed of so-called cores and molds. Different requirements are placed on the cores and molds. In molds, a relatively large surface area is available to dissipate gases that form during casting by the action of the hot metal. In cores usually only a very small area is available, through which the gases can be derived. If there is too much gas, there is a risk that gas will pass from the core into the liquid metal and lead to the formation of casting defects.
• the internal cavities are therefore imaged by cores solidified by cold box binders, a polyurethane based binder, while the outer contour of the casting is represented by lower cost molds, such as a Green sand mold, a form bound by a furan resin or a phenol resin, or by a steel mold.
• lower cost molds such as a Green sand mold, a form bound by a furan resin or a phenol resin, or by a steel mold.
• organic polymers are mostly used as binders for the refractory, granular molding material.
• granular molding material often washed, classified quartz sand is used, but also other molding materials such. Zirconsande, Chromitsande, chamois, olivine sands, feldspat ambience sands and Andalusitsande.
• the molding material mixture obtained from mold base and binder is preferably present in a free-flowing form.
• organic binders such as polyurethane, furan resin or epoxy-acrylate used in which the curing of the binder by addition of a catalyst.
• Phenol resins acid-curing or - in the Alpha-Set-process ester-curing are also used.
• binder depends on the shape and size of the casting to be produced, the conditions of production and the material used for the casting. For example, in the production of small castings that are produced in large numbers, polyurethane binders are often used because they allow fast cycle times and thus also a series production.
• Processes in which the curing of the molding material mixture by heat or by subsequent addition of a catalyst have the advantage that the processing of the molding material mixture is not subject to any special time restrictions.
• the molding material mixture can first be produced in larger quantities, which are then processed within a longer period of time, usually several hours.
• the curing of the molding material mixture takes place only after molding, with a rapid reaction is sought.
• the mold can be removed immediately after curing from the mold so that short cycle times can be realized. However, in order to obtain a good strength of the mold, the curing of the molding material mixture must be uniform within the mold. If the curing of the molding material mixture by subsequent addition of a catalyst, the mold is gassed after molding with the catalyst. For this purpose, the gaseous catalyst is passed through the casting mold.
• the molding material mixture cures directly after contact with the catalyst and can therefore be removed very quickly from the mold.
• the gassing times are prolonged, but can still arise sections in the mold, the very poor or not at all of the gaseous catalyst be achieved.
• the amount of catalyst therefore increases sharply with increasing size of the mold.
• the weight of the cores is often about 1000 kg or more.
• methods in which the hardening with gas or by heat such large cores are difficult or impossible to produce from a technical point of view.
• cold-curing methods are used.
• no-bake binder In the production of molds for large castings, such as engine blocks of marine diesel engines or large machine parts, such as hubs of rotors for wind power plants, so-called “no-bake binder” are used for the reasons mentioned mostly.
• the refractory base material for example sand
• a catalyst hardener
• the binder is added and distributed evenly on the already catalyst-coated grains of the refractory base molding material by mixing.
• continuous flow mixers In this process is often worked with so-called continuous flow mixers.
• the resulting molding material mixture can then be shaped into a shaped body. Since binder and catalyst are evenly distributed in the molding material mixture, the curing is largely uniform even with large moldings.
• the refractory base stock e.g., sand
• the refractory base stock may be first mixed with the binder and then the hardener added.
• the refractory base stock e.g., sand
• it may, especially in the production of molds for large castings, come because of a partial, local too high concentration of the curing agent to partial hardening or crosslinking of the binder, whereby an inhomogeneous molding material would be obtained.
• the curing of the molding material mixture begins immediately after its preparation.
• the components of the molding material mixture should be coordinated.
• the reaction rate for a given amount of the binder and the refractory base molding material for example, by the nature and amount of the catalyst or by Adding delaying components influence.
• the processing of the molding material mixture should be carried out under very controlled conditions, since the rate of curing is influenced for example by the temperature of the molding material mixture.
• the "classic" no-bake binders are often based on furan resins and phenolic resins. They are often offered as systems (kits) wherein one component comprises a reactive furan resin and the other component comprises an acid, which acid acts as a catalyst for the curing of the reactive resin component.
• Furan and phenolic resins show very good disintegration properties during casting. Under the action of heat of the liquid metal, the furan or phenolic resin decomposes and the strength of the mold is lost. After casting, therefore, cores, possibly after prior shaking of the casting, pour out very well from cavities.
• Furfuryl alcohol contains reactive furan resins, which regularly comprise furfuryl alcohol as an essential component. Furfuryl alcohol can react with itself under acid catalysis and form a homopolymer. Furfuryl alcohol is generally not used alone for the preparation of furan no-bake binders, but further compounds are added to the furfuryl alcohol which are copolymerized into the resin. Examples of such compounds are aldehydes, such as formaldehyde or furfural, ketones, such as acetone, phenols, urea or polyols, such as sugar alcohols or ethylene glycol. The resins may be added with other components that affect the properties of the resin, such as its elasticity. Melamine can be added, for example, to bind still free formaldehyde.
• Furan no-bake binders are most often prepared by first producing precondensates of, for example, urea, formaldehyde, and furfuryl alcohol under acidic conditions. These precondensates are then diluted with furfuryl alcohol.
• urea and formaldehyde are reacted alone.
• This produces so-called UF resins ("urea formaldehyde” resins, "aminoplasts”). These are usually subsequently diluted with furfuryl alcohol.
• Advantages of this manufacturing method are a higher flexibility / variability in the product range and lower costs, because it is cold mixing processes.
• the disadvantage is that certain chemical and performance properties can not be achieved.
• UF resins are often cloudy, so that binders usually made therefrom are also cloudy and inhomogeneous.
• Resoles can also be used to prepare furan no-bake binders. Resoles are prepared by polymerization of mixtures of phenol and formaldehyde. These resoles are then often diluted with a large amount of furfuryl alcohol.
• Furan no-bake binders are regularly cured with an acid. This acid catalyzes the crosslinking of the reactive furan resin. It should be noted that, depending on the type of binder, certain amounts of acid should not be exceeded, since alkaline components, which may be present in the refractory base molding material, can partially neutralize the acid.
• acids are sulfonic acids, phosphoric acid or sulfuric acid. In some specific cases, combinations of these are used, inter alia, in combination with other carboxylic acids. Further, certain "curing moderators" can be added to the furan no-bake binder.
• Phosphoric acid is often used as an acid catalyst for curing in concentrated form, i. H. used at concentrations greater than 70%.
• it is only suitable for the catalytic hardening of furan resins with a relatively high proportion of urea, since essentially the curing of the aminoplast moiety in the furan no-bake binder is responsive.
• the nitrogen content of such resins is usually more than 2.0% by weight.
• Sulfuric acid as a relatively strong acid, can be added as a starter for the curing of furan resins to weaker acids. During casting, however, a smell typical of sulfur compounds develops. In addition, there is a risk that the casting material sulfur is absorbed, which affects its properties.
• the selection of the acid catalyst for curing has a significant influence on the curing behavior of the binder, the properties of the molding material mixture and the casting mold or the core obtainable therefrom.
• the rate of curing can be influenced by the amount and the strength of the acid.
• High amounts of acid or stronger acids lead to an increase in the curing rate.
• the processing time of the molding material mixture is shortened too much, so that the workability is greatly impaired or even processing is no longer possible.
• the binder such as a furan resin
• the binder also become brittle upon curing, which adversely affects the strength of the mold.
• too small amounts of acid catalyst the resin is not completely cured (or the curing takes a long time), resulting in lower strength of the mold.
• reclaimed mold base material eg sand
• refractory Form base materials that have been solidified with furan no-bake binders can be worked up very well again.
• the workup is carried out either mechanically by mechanically rubbing off a shell formed from residual binder or by thermally treating the used sand. With mechanical workup or with combined mechanical / thermal processes, return rates of up to almost 100% can be achieved.
• Phenolic resins the second large group of acid-catalyzed curable no-bake binders, contain resoles as reactive resin components, ie phenolic resins prepared with a molar excess of formaldehyde. Phenolic resins show lower reactivity compared to furan resins and require strong sulfonic acids as catalysts. Phenolic resins show a relatively high viscosity, which increases even more with prolonged storage of the resin.
• the molding compound After the phenol no-bake binder has been applied to the refractory base molding material, the molding compound should be processed as promptly as possible so as not to suffer deterioration in the quality of the molding compound due to premature curing, resulting in deterioration of the strength of the molding compound mixture produced molds can lead.
• the flowability of the molding material mixture is usually worse than a comparatively produced molding material with a furan no-bake binder. In the production of the mold, the molding material mixture must therefore be carefully compacted in order to achieve a high strength of the mold can.
• the preparation and processing of such a molding material mixture should take place at temperatures in the range of 15 to 35 ° C. If the temperature is too low, the molding material mixture can be processed worse because of the high viscosity of the phenol no-bake resin. At temperatures of more than 35 ° C, the processing time is shortened by premature curing of the binder.
• molding mixtures based on phenol no-bake binders can also be worked up again, in which case mechanical or thermal or combined mechanical / thermal processes can also be used.
• the acid used as catalyst in the case of furan or phenol no-bake processes has a very great influence on the properties of the casting mold.
• the acid must have sufficient strength to ensure a sufficient rate of reaction in the curing of the mold.
• the curing should be well controllable, so that also sufficiently long processing times can be set. This is particularly important in the production of molds for very large castings, the construction requires a longer period. Furthermore, the acid must not accumulate in the regeneration during the regeneration of used materials (ie mold materials already used for the production of lost molds or cores, for example old sands). If acid is introduced into the molding material mixture via the regenerate, this shortens the processing time and leads to a deterioration in the strength of the casting mold produced from the regenerate.
• Phosphoric acid is, as already explained, only for the curing of certain furan resin qualities.
• phosphoric acid is not suitable for the curing of phenolic resins.
• phosphoric acid tends to accumulate in the regenerate, making it difficult to reuse the regenerate.
• Sulfuric acid during casting and during thermal regeneration leads to the emission of sulfur dioxide, which has corrosive properties, is harmful to health and represents an odor nuisance.
• sulfuric acid see below.
• no-bake binders have one or more of the following disadvantages or undesirable properties: too high a content of furfuryl alcohol, too high a content of water, too high a content of formaldehyde, too strong an odor, too high a content of ammonia and / or too high total content of nitrogen.
• US 3,644,274 relates primarily to a no-bake process using certain mixtures of acid catalysts to cure for furfuryl alcohol-formaldehyde-urea resins.
• US 3,806,491 relates to binders which can be used in the no-bake process.
• the binders used there include products from the reaction of paraformaldehyde with certain ketones in a basic medium, as well as furfuryl alcohol and / or furan resins.
• US 5,607,986 describes thermosetting binders for the production of molds and foundry cores in the "hot box” or “hot box” process based on furfuryl alcohol-formaldehyde phenolic resins prepared in the basic medium at pH's in the range of 8 to 9.
• the binders according to US 5,607,986 also contained furfuryl alcohol and polyvinyl acetate.
• US 5,491,180 describes resin binders suitable for use in the no-bake process.
• the binders used there are based on 2,5-bis (hydroxymethyl) furan or methyl or ethyl ethers of 2,5-bis (hydroxymethyl) furan, wherein the binder 0.5 to 30 wt .-% water and regularly contain a high proportion on furfuryl alcohol.
• EP 0 540 837 proposes low-emission, cold-curing binders based on furan resins and lignin from the Organosolv process.
• the furan resins described there contain a high proportion of monomeric furfuryl alcohol.
• EP 1 531 018 relates to no-bake foundry binder systems consisting of a furan resin and certain acid hardeners.
• the binder systems described therein preferably comprise 60 to 80% by weight of furfuryl alcohol.
• US 4,176,114 A discloses a method of making sand molds and cores.
• sand is mixed with an acid-curing resin, which comprises "high viscosity poly furfuryl alcohol”. Curing then takes place by contacting the mixture with gaseous sulfur dioxide in the presence of an oxidizing agent.
• US 5,741,914 A discloses resin-based binder compositions comprising reaction products of furfuryl alcohol with formaldehyde.
• the binder compositions comprise, in part, a weak organic acid and in some cases only a small amount of formaldehyde.
• the lowest possible total nitrogen content is desirable, since in particular a total nitrogen content of 4% by weight or higher in a no-bake binder can lead to casting defects.
• a no-bake binder should have the lowest possible total nitrogen content, since there surface defects, such as "pinholes" (pinholes) occur as a casting error.
• pinholes are the "water-nitrogen pinholes,” in which water vapor reacts with the iron and nitrogen-containing components to form metal oxides and nitrogen-hydrogen compounds that diffuse into the liquid metal, resulting in micropores.
• ammonia content in no-bake binders for large-scale casting processes must also be kept as low as possible, and preference should be given to dispensing with the use of ammonia.
• AGW workplace limit value
• the invention was therefore based on the object to provide a binder based on furfuryl alcohol and formaldehyde available, which can be used in a no-bake process for the production of cores and molds for the foundry industry, so that in the production of molds and cores and / or during casting a low emission of pollutants, especially with respect to furfuryl alcohol and formaldehyde and preferably also ammonia.
• reaction mixtures according to the invention (as defined below) containing a mixture according to the invention
• the pollutant emission in particular the emission of furfuryl alcohol and formaldehyde
• the good processability of reaction mixtures which comprise mixtures according to the invention is based inter alia on their comparatively low viscosity (for preferred viscosities, see below).
• the other relevant properties of a no-bake binder include the influence on the curing behavior (in particular depending on the water content, see below) and the influence on the stability of corresponding shapes or cores in spontaneous contact with liquid metal (especially depending on the water content, see below for comments on blasting molds and cores in the casting shop).
• mixtures according to the invention and the reaction mixtures according to the invention can also be used in particular in the field of large-scale casting, preferably for producing molds and cores, in particular cores, having a weight of 800 kg or more, preferably 900 kg or more preferably 1000 kg or more.
• Refractory mold raw materials which were solidified using a mixture according to the invention in the no-bake process, can be worked up very well again. This is especially true for sand.
• furan resins known in the art that do not relate to the foundry industry.
• the furan resins described therein are not suitable for use in the foundry industry as a no-bake binder (ie not suitable for use in the no-bake process), as these in particular had one or more of the following disadvantages: too high viscosity, too high content Water, too high content of formaldehyde, too high ammonia content and / or too high total nitrogen content.
• no acceptable curing processes and no buildup of sufficient strength are regularly achieved when used in no-bake processes.
• US 2,343,972 describes resins obtained by reacting furfuryl alcohol and formaldehyde under heating in the presence of an acid such as lactic acid, formic acid or chloroacetic acid become. Concrete data on properties that are important for binders in the no-bake process are missing in US 2,343,972 ,
• DE 21 26 800 (and accordingly CA 1 200 336 ) describes a method for producing a composite article and binders suitable therefor, wherein the binders are highly viscous resinous condensation products based on furan-formaldehyde, which are diluted with water.
• US 3,816,375 discloses partially prepolymerized furfuryl alcohol-aldehyde binders wherein the aldehyde is formaldehyde and / or furfural used there to form composites. If the material chosen for the composite is glass fiber, then US 3,816,375 Preferably, a prepolymerized high viscosity furfuryl alcohol aldehyde binder is used which is diluted with furfural. Similar is in US 3,594,345 (and accordingly DE 19 27 776 ) disclosed.
• US 2,874,148 discloses furfuryl alcohol-formaldehyde resins prepared by reacting furfuryl alcohol with formaldehyde in the presence of sulfuric acid.
• the physical properties of according to US 2,874,148 obtained resins depend very much on the respective further reaction conditions.
• a mixture according to the invention for use as a binder in the no-bake method does not comprise an acid which has a pKa value of less than 2 at 25 ° C., preferably no acid which at 25 ° C. has a pKa value of less than 2 , 5. If, in exceptional cases, such acids are used, their maximum total amount is preferably less than 5 wt .-%, based on the total mass of the mixture. This applies to all mixtures according to the invention described below.
• a mixture according to the invention for use as a binder in the no-bake process does not comprise refractory granular substances. If refractory granular materials are used in the mixture in exceptional cases, their maximum total amount is preferably less than 5 wt .-%, based on the total amount of the mixture. This applies to all mixtures according to the invention described below.
• a mixture according to the invention is a homogeneous solution; This applies to all preferred mixtures according to the invention described below.
• a mixture according to the invention preferably contains less than 5% by weight of monomeric furfural, preferably less than 3% by weight, more preferably less than 1% by weight of monomeric furfural.
• the mixtures according to the invention preferably contain less than 3% by weight of polyvinyl acetate, preferably less than 1% by weight, more preferably they are free of polyvinyl acetate.
• a mixture according to the invention preferably contains less than 5% by weight of monomeric furfural and less than 3% by weight of polyvinyl acetate.
• a blend according to the invention contains less than 1% by weight of monomeric furfural and less than 1% by weight of polyvinyl acetate.
• the mixtures according to the invention comprise the compound 2,5-bis (hydroxymethyl) furan (BHMF), preferably in an amount of at least 2% by weight, more preferably in an amount of from 5 to 80 Wt .-%, particularly preferably in an amount of 10 to 70 wt .-%, in particular in an amount of 20 to 60 wt .-%, each based on the total weight of the component (b-1).
• BHMF 2,5-bis (hydroxymethyl) furan
• the blends of the invention in component (b-1) comprise 2,5-bis (hydroxymethyl) furan (BHMF) in an amount of at least 1% by weight, more preferably in an amount of from 5 to 40% by weight preferably in an amount of 10 to 35 wt .-%, particularly preferably in an amount of 15 to 30 wt .-%, based on the total weight of a mixture according to the invention.
• BHMF 2,5-bis (hydroxymethyl) furan
• a blend of the invention comprises monomeric furfuryl alcohol (component (a)) and 2,5-bis (hydroxymethyl) furan (BHMF) (as part of component (b-1)) in a weight ratio in the range of 3: 1 to 1: 3 , preferably in the range from 2: 1 to 1: 2, more preferably in the range from 3: 2 to 2: 3, particularly preferably in the range from 5: 4 to 4: 5.
• component (a) monomeric furfuryl alcohol
• BHMF 2,5-bis (hydroxymethyl) furan
• the proportion of "furan ring units" can be determined via the furan ring, for example via 13 C-NMR.
• component (b-2) nitrogen-containing components are contained in component (b-2), their detection via the nitrogen itself is possible.
• phenol compound as a component in Component (b-2) is also possible to differentiate via the phenol body (for example determination of the residual monomer content, GC-MS analysis).
• the proportion of "furan ring” units can be determined via 13 C-NMR.
• the proportion of "furan ring” units, calculated as furfuryl alcohol (C5H6O2), in the reaction product (b-1) from formaldehyde with furfuryl alcohol and optionally further constituents is preferably in the range from 60 to 96% by weight, preferably in the range from 70 to 95 wt .-%, more preferably in the range of 75 to 90 wt .-%, particularly preferably in the range of 75 to 85 wt .-%, each based on the total mass of the component (b-1).
• the particularly preferred organic compound which has one or more H 2 N groups is urea.
• the phenol compound (s) can be reacted under acidic conditions with furfuryl alcohol and formaldehyde directly or with a furfuryl alcohol / formaldehyde precondensate.
• the phenol compounds are preferably phenol compounds having 6 to 25 carbon atoms and / or one, two, three or four hydroxyl groups bonded directly to an aromatic ring, preferably selected from the group consisting of phenol, optionally C 1 -C 4 -alkyl- mono- or disubstituted dihydroxybenzenes, trihydroxybenzenes, methylphenols and bisphenols, more preferably selected from the group consisting of phenol, o-dihydroxybenzene, m-dihydroxybenzene (resorcinol), p-dihydroxybenzene, 5-methylresorcinol, 5-ethylresorcinol, 2.5- Dimethylresorcinol, 4,5-dimethylresorcinol, 1,2,3-trihydroxybenzene, 1,3,5-trihydroxybenzene o-cresol, m-cresol, p-cresol and bisphenol A. Particularly preferred are phenol, resorcinol and bisphenol A.
• Component (b-2) may be, for example, formaldehyde-phenolic resins which, when reacted with formaldehyde and phenol and optionally with another component which is not furfuryl alcohol, may be obtained under alkaline conditions.
• component (b-1) and, if present, component (b-2) of a mixture according to the invention can prepare component (b-1) and, if present, component (b-2) of a mixture according to the invention separately and in a targeted manner.
• the constituents (b-1) and (b-2) may initially (preferably in the proportions specified as preferred) initially mixed together and as component (b) or alternatively in separate form as (b-1) and (b-2) be introduced into a mixture according to the invention.
• the order of constituents (a) to (d) in the preparation of a mixture according to the invention does not play any significant role.
• the ingredients (a) to (d) are mixed together at a temperature in the range of 0 to 70 ° C, preferably at a temperature in the range of 10 to 60 ° C, more preferably at a temperature in the range of 15 to 50 ° C, for example at 18 to 25 ° C.
• the components (b-1) and (b-2) in a reaction by reacting furfuryl alcohol and formaldehyde in the presence of the component (d), preferably in a one-pot reaction.
• the reaction is preferably carried out so that the components (a) and (b) (ie component (b-1) and optionally component (b-2)) and the components (c) and (d) of a mixture according to the invention in the desired proportions (preferably in the proportions given as preferred) can be obtained.
• the subsequent or separate addition of monomeric furfuryl alcohol (component (a)) is not required.
• the mixtures according to the invention contain water (component (c)).
• the proportion of water is preferably chosen to be low.
• the proportion of water in a mixture according to the invention is less than 20 wt .-%, preferably at most 15 wt .-%.
• Preferred mixtures according to the invention contain water in an amount in the range from 5 to 15% by weight, more preferably in an amount in the range from 7 to 14% by weight, particularly preferably in an amount in the range from 8 to 13% by weight. , wherein the percentages by weight are based on the total mass of the mixture according to the invention.
• a preferred mixture according to the invention is characterized in that the mixture at 20 ° C has a viscosity of at most 300 mPas in accordance with DIN 53019-1: 2008-09, preferably at most 250 mPas, preferably at most 200 mPas, more preferably at most 150 mPas.
• the viscosity is determined according to DIN 53019-1: 2008-09, i. according to DIN 53019-1 of September 2008, and refers to measurements at 20 ° C.
• the viscosity is given in the context of the present text in the unit millipascal seconds (as mPas or mPa * s).
• the viscosity is preferably determined according to DIN 53019-1 with a rotational viscometer at 20 ° C., for example using a Haake VT 550 rotational viscosimeter.
• the viscosity values determined in the context of the present invention were determined using a cylinder (spindle) SV1 and a measuring cup (tube). SV measured.
• the speed used in the measurement of the viscosity with the rotational viscometer was at a viscosity of the sample to be examined of less than 100 mPas at 20 ° C and 800 rpm (revolutions / min.); at a viscosity of the test sample of 100 to 800 mPas was measured at a speed of 500 rpm at 20 ° C.
• Such a mixture according to the invention has, despite a low water content of at most 15 wt .-% at the same time a low viscosity, which in the foundry (after mixing with mold base) causes excellent processability of the resulting molding material mixture.
• the preferred mixtures according to the invention have proven their worth, in particular because of their good and reproducible meterability in continuous flow mixers. In practice, for example, 35 t of sand mixture or more per hour are mixed continuously for given screw geometries (furan-resin resin plants).
• a good "atomization" of the mixture of the invention is important here to ensure the most uniform and homogeneous distribution in the molding material during the short mixing time.
• Such a mixture according to the invention moreover leads to good flowability, e.g. a freshly prepared sand mixture during mold filling.
• mold contours and undercuts should generally be filled well and compacted.
• Higher viscosity binders tend to clog and poorly flow the sand mixture as compared to the preferred blends of the invention, resulting in surface casting defects due to poorer densification.
• a preferred mixture according to the invention is characterized in that the content of free formaldehyde is at most 0.4% by weight, preferably at most 0.3% by weight, preferably at most 0.2% by weight, based on the total mass of the mixture ,
• constituent (d) it is preferred to use one or more organic acids having a pKa value in the range from 2.75 to 6 at 25 ° C., preferably in the range from 3 to 5, and / or salts thereof.
• Organic acids having a pKa in these ranges are particularly suitable condensation catalysts for preparing the reaction products of formaldehyde with furfuryl alcohol and optionally other constituents of component (b-1).
• Citric acid lactic acid, benzoic acid, phthalic acid, I-malic acid, d-tartaric acid, maleic acid, glycolic acid, glyoxylic acid, 2,4-dihydroxybenzoic acid and salicylic acid are suitable as organic acids of component (d) of a mixture according to the invention.
• Preferred organic acids of the component (d) are selected from the group consisting of benzoic acid, lactic acid, citric acid, phthalic acid, 2,4-dihydroxybenzoic acid, salicylic acid and their salts, since these acids have achieved particularly good results in the context of the present invention, wherein With benzoic acid, lactic acid or citric acid particularly good results and with benzoic acid the best results were obtained.
• phase compatibility of benzoic acid in the mixture according to the invention has proven to be particularly good in own investigations; no crystallization reaction was observed.
• component (d) is possible but not preferred.
• organic acids e.g. Acetic, propionic and butyric acids, and in some cases foul-smelling acids.
• succinic acid and adipic acid show a rapid crystallization tendency. The presence of these other organic acids in a mixture according to the invention is therefore not preferred.
• the total amount of constituent (d) is from 0.5 to 8% by weight, preferably from 0.75 to 5% by weight, more preferably from 1 to 3% by weight, based in each case on the total mass of the mixture ,
• a preferred mixture according to the invention is therefore one in which component (d) comprises an acid or a salt selected from the group consisting of benzoic acid, lactic acid, citric acid, phthalic acid, 2,4-dihydroxybenzoic acid, salicylic acid and their salts.
• Salicylic acid is somewhat less preferred because it adversely affects the shelf life of a mixture according to the invention in some cases and in some cases, a comparatively low water miscibility of mixtures according to the invention prepared with salicylic acid was found.
• a preferred mixture according to the invention is one which has a content of ammonia of at most 1% by weight, preferably of at most 0.5% by weight, preferably of at most 0.25% by weight, based on the total mass of the mixture.
• a preferred mixture according to the invention has a total nitrogen content of at most 4% by weight, preferably of at most 3.5% by weight, preferably of at most 3.0% by weight, based on the total mass of the mixture.
• the total content of nitrogen can be determined, for example, by elemental analysis or by the so-called Kjeldahl method (according to DIN 16916-02, point 5.6.4), the elemental analysis for determining the total nitrogen content of a mixture according to the invention being preferred.
• a preferred mixture according to the invention is a mixture whose total content of compounds having a molecular weight of greater than 5000 daltons (g / mol) is at most 3% by weight, preferably at most 1% by weight, determined by gel permeation chromatography according to DIN 55672-1 (February 1995), where the weight percentages refer to the total mass of the mixture.
• the molecular weights indicated below refer to molecular weights determined by gel permeation chromatography (GPC) in accordance with DIN 55672-1 (February 1995), the detection in the present case preferably taking place with a UV detector at a wavelength of 235 nm.
• the total content of compounds having a molecular weight of greater than 4000 daltons (g / mol) is at most 3% by weight, preferably at most 1% by weight.
• the total content of compounds having a molecular weight of greater than 3000 daltons (g / mol) is at most 5% by weight, preferably at most 2% by weight.
• constituent (b-1) does not comprise any compounds having a molecular weight greater than 5000 daltons, more preferably no compounds having a molecular weight greater than 4000 daltons.
• constituent (b-1) comprises at most 3% by weight of compounds having a molecular weight of greater than 3000 daltons.
• constituent (b-1) comprises at most 5% by weight of compounds with a molecular weight of greater than 2000 daltons.
• the weight average molecular weight M.sub.w (weight average) of constituent (b-1) is in the range from 200 to 600 g / mol, more preferably in the range from 225 to 500 g / mol, particularly preferably in the range from 250 to 450 g / mol, most preferably in the range of 300 to 425 g / mol.
• the ratio of weight average molecular weight M w to number average molecular weight M n of the component (b-1) is in the range from 5: 1 to 9: 8, more preferably in the range from 4: 1 to 6 : 5, more preferably in the range of 3: 1 to 4: 3, particularly preferably in the range of 2: 1 to 3: 2.
• the ratio of molar mass average Mw to molar mass average Mn of the two constituents (a) and (b-1) together is in the range from 5: 1 to 9: 8, more preferably in the range from 4: 1 to 6 : 5, more preferably in the range of 3: 1 to 4: 3, particularly preferably in the range of 2: 1 to 3: 2.
• the ratio of weight average (molecular weight average M w ) to number average (molecular weight average M n ) is also referred to as polydispersity, which is often given in GPC spectra with D as the ratio.
• Polydispersity is a measure of the width of a molecular weight distribution. The larger the D, the broader is the molecular weight distribution (a discrete compound has a polydispersity of 1).
• the mixtures according to the invention may preferably contain, for example, one or more adhesion promoters, preferably one or more silanes.
• Suitable silanes are, for example, aminosilanes, epoxysilanes, mercaptosilanes, hydroxysilanes and ureidosilanes, such as gamma-hydroxypropyltrimethoxysilane, gamma-aminopropyl-methyl-diethoxysilane, gamma-aminopropyltrimethoxysilane, gamma-aminopropyltriethoxysilane, 3-ureidopropyltriethoxysilane, gamma-mercaptopropyltrimethoxysilane, gamma-glycidoxypropyltrimethoxysilane, beta- ( 3,4-epoxycyclohexyl) trimethoxysilane, N-beta- (aminoethyl) -gamma-aminopropyltrimethoxysilane.
• Gamma-aminopropylmethyldiethoxysilane (N-aminopropylmethyldiethoxysilane) is marketed under the trade names Silan 1100, Silane 1101 and Silane 1102 (engineering grade) and AMEO T and gamma-aminopropyltriethoxysilane (N-aminopropyltriethoxysilane) under Dynasilan 1505 and 1506 (technical grade). Also suitable are silanes available under the trade names DAMO, DAMO-T and Dynasilan 1411.
• mixtures according to the invention comprising one or more silanes, in particular one or more silanes from the group of N-aminopropylmethyldiethoxysilane, N-aminoethyl-3-aminopropyltrimethoxysilane, N-aminoethyl-3-aminopropylmethyldiethoxysilane and / or N-aminopropyltriethoxysilane have achieved particularly good results in the production of casting molds or cores, especially with N-aminopropylmethyldiethoxysilane and / or N-aminopropyltriethoxysilane.
• the mixtures according to the invention may contain further additives.
• they may contain, for example, diols or aliphatic polyols as curing moderators, which lead to a lowering of the reactivity.
• the proportion of these curing moderators in a mixture according to the invention should not be too high, since such curing moderators can lead to a reduction in the strength of the casting mold in the unfavorable case.
• the proportion of curing moderators is therefore preferably at most 10 wt .-%, preferably at most 5 wt .-%, based on the total mass of the mixture.
• Preferred organic curing moderators of component (f) are glycols having 2 to 12 carbon atoms, more preferably glycols having 2 to 6 carbon atoms, especially preferred is ethylene glycol, i. Monoethylene glycol.
• the amount of ethylene glycol is preferably at most 10 wt .-%, preferably at most 5 wt .-%, based on the total mass of the mixture according to the invention.
• Preferred aldehydes which form reaction products with furfuryl alcohol according to component (h) of a mixture according to the invention are acetaldehyde, propionaldehyde, butyraldehyde, acrolein, crotonaldehyde, benzaldehyde, salicylaldehyde, cinnamaldehyde, glyoxal and mixtures of these aldehydes, with glyoxal in turn being preferred.
• Preferred aldehyde having 2 or more carbon atoms of the component (h) and / or the component (s) of a mixture according to the invention is glyoxal, since it is not only readily available and advantageous from an economic point of view, but also brings about technical advantages of a mixture according to the invention. For example, even small quantities of glyoxal as constituent (s) but also reaction products of furfuryl alcohol and glyoxal as constituent (h) have a positive influence on the reactivity of a mixture according to the invention.
• a mixture according to the invention comprises constituent (s)
• the total amount of constituent (s) is preferably at most 5% by weight, preferably at most 3% by weight, based on the total mass of the mixture.
• Preferred phenolic compounds of component (k) of a mixture according to the invention are phenol compounds having 6 to 25 C atoms and one, two, three or four hydroxyl groups directly bonded to an aromatic ring. Further preferred phenolic compounds are selected from the group consisting of phenol, optionally C1-C4-alkyl mono- or di-substituted dihydroxybenzenes, trihydroxybenzenes, methylphenols and bisphenols, more preferably selected from the group consisting of phenol, o-dihydroxybenzene, m-dihydroxybenzene (resorcinol), p Dihydroxybenzene, 5-methylresorcinol, 5-ethylresorcinol, 2,5-dimethylresorcinol, 4,5-dimethylresorcinol, 1,2,3-trihydroxybenzene, 1,3,5-trihydroxybenzene o-cresol, m-cresol, p-cresol and Bisphenol A (2,2-bis- (4-hydroxyphenyl
• Component (k) comprises or consists preferably of phenol, resorcinol and / or bisphenol A, since in particular these free phenols show a high affinity for reaction with formaldehyde and react rapidly with any formaldehyde still present, whereby the emission, in particular of formaldehyde, is further reduced can be, especially during the curing process.
• Bisphenol A is particularly advantageous in this context, since it-presumably because of its diphenylmethane skeleton-leads to a higher strength of the resulting molds and cores after curing of a mixture according to the invention as a constituent of a reaction mixture according to the invention.
• a higher thermal stability is observed, in particular during the casting process, whereby a further positive effect with respect to the emission can be achieved.
• a preferred mixture according to the invention may additionally comprise benzyl alcohol as constituent (m), preferably in an amount of at most 15% by weight, based on the total mass of the mixture.
• benzyl alcohol which serves as component (m) mainly as solvent in a mixture according to the invention, further improves the desired properties of a mixture according to the invention.
• the advantage lies inter alia in the very good compatibility with the other constituents of a mixture according to the invention. It has also been found that lowering the viscosity, i. Also the viscosity value, takes place and beyond the storage stability of a mixture according to the invention is further improved.
• a preferred mixture according to the invention has a pH in the range from 4 to 10 at 25 ° C., preferably in the range from 5 to 9.5.
• a mixture according to the invention preferably has a pH in the range from 5 to 7 or in the range from 8 to 9.5 at 25 ° C.
• the preferably adjusted pH values of a mixture according to the invention which is usually a solution, result in excellent storage stability.
• the reaction mixture preferably has a content of free formaldehyde of at most 0.4% by weight, the percentages by weight being based on the total mass of the reaction mixture minus the total mass of refractory granular substances in the reaction mixture.
• Component (ii) is also referred to as acid hardener.
• the acid hardener allows the curing of a mixture according to the invention at low temperatures, typically at ambient temperature.
• the amount of component (ii) used is preferably such that hardening of the mixture according to the invention already results at low temperatures, typically at ambient temperature, in particular at 25 ° C.
• the total amount of acid used with a pKa of less than 2 at 25 ° C is such that the pH of the resulting reaction mixture is less than 3, preferably even less than 1.
• the acid hardener then advantageously causes a curing of the mixture according to the invention already at 25 ° C.
• Component (ii) of a reaction mixture according to the invention preferably comprises or consists preferably of organic sulfonic acids.
• organic sulfonic acids such as benzenesulfonic acid, toluenesulfonic acids, xylenesulfonic acids or cumene sulfonic acid [2 (or 4) - (isopropyl) -benzenesulfonic acid ]
• methanesulfonic acid and ethanesulfonic acid are also preferred.
• the organic sulfonic acids are readily available and have a sufficiently high acid strength to achieve the desired curing of a mixture according to the invention in the no-bake process. In the context of the present invention, the best results were achieved with p-toluenesulfonic acid.
• the acid of component (ii) is selected from the group of organic acids, preferably of organic sulfonic acids, preferably selected from the group consisting of benzenesulfonic acid, Toluenesulfonic acids, xylenesulfonic acids, cumene sulfonic acid [2 (or 4) - (isopropyl) benzenesulfonic acid ] and methanesulfonic acid, particularly preferred is p-toluenesulfonic acid.
• organic acids preferably of organic sulfonic acids, preferably selected from the group consisting of benzenesulfonic acid, Toluenesulfonic acids, xylenesulfonic acids, cumene sulfonic acid [2 (or 4) - (isopropyl) benzenesulfonic acid ] and methanesulfonic acid, particularly preferred is p-toluenesulfonic acid.
• the reaction mixture comprises (i) no sulfuric acid or (ii) sulfuric acid in an amount of at most 1 wt .-%, preferably at most 0.5 wt .-%, wherein the weight percentages are based on the total mass of the reaction mixture minus the total mass of ( optional) refractory granular substances in the reaction mixture.
• the reaction mixture comprises no phosphoric acid and no hydrochloric acid; more preferably, the reaction mixture according to the invention comprises no mineral acids at all.
• sulfuric acid the strength of the acid is in some cases problematic. Experience has shown that binders which are cured only with sulfuric acid, a "spontaneously" generated polymer network with inevitably more defects.
• Aromatic sulfonic acids are very good resin-miscible (have a good phase compatibility).
• the ongoing hardening is more orderly, more homogeneous, more complete and also better controllable compared to sulfuric acid.
• part of the organically bound sulfur evaporates during the casting process as SO 2 from the molding material out. As a result, a lower desulfurization is observed.
• the less corrosive sulfonic acids are also positive in comparison with sulfuric acid (tool life is positively influenced).
• a reaction mixture according to the invention preference is given to using acid having a pKa of less than 2 at 25 ° C. in a total amount of from 10 to 80% by weight, preferably from 15 to 70% by weight, preferably from 20 to 60% by weight. -%, particularly preferably from 25 to 50 wt .-%, each based on the total mass of formaldehyde and the components (a), (b), (c), (d), (e), (f), (g ), (h), (j), (k) and (n) the mixture of the invention (component (i)).
• the total amount of acid or acids having a pKa of less than 2 at 25 ° C. in a reaction mixture according to the invention is preferably in the range from 9 to 45% by weight, preferably from 13 to 41% by weight, preferably from 16 to 38% by weight .-%, particularly preferably from 20 to 33 wt .-%, based on the total mass of the reaction mixture according to the invention less the total mass of any existing refractory granular materials.
• a reaction mixture according to the invention comprises, besides a mixture according to the invention (constituent (i)), an acid hardener (constituent (ii)) and a refractory granular substance (constituent (iii)), a molding material mixture is present.
• reaction mixtures according to the invention which do not comprise sulfur dioxide or comprise no peroxide (in particular methyl ethyl ketone peroxide), preferably those which comprise neither sulfur dioxide nor a peroxide (in particular methyl ethyl ketone peroxide).
• Refractory mold raw materials which were solidified using a reaction mixture according to the invention in the no-bake process, can be worked up very well again. This is especially true for sand.
• a reaction mixture according to the invention preferably comprises sand, preferably having a particle size in the range from 0.063 to 2 mm, preferably with a particle size in the range from 0.1 to 1 mm.
• a reaction mixture according to the present invention preferably comprises 80% by weight or more of the component (iii), preferably 95% by weight or more, based on the total weight of the reaction mixture (i.e., the molding material mixture).
• component (iii) comprises or consists of sand, preferably aluminum silicate sand, feldspar sand and / or quartz sand.
• Component (iii) particularly preferably comprises quartz sand, more preferably component (iii) consists of quartz sand.
• Formaldehyde can be used both in monomeric form, for example in the form of a formalin solution, as well as in the form of its polymers, such as trioxane or paraformaldehyde, wherein according to the invention, the use of paraformaldehyde is preferred.
• aldehydes can additionally be used. Suitable aldehydes are, for example, acetaldehyde, propionaldehyde, butyraldehyde, acrolein, crotonaldehyde, benzaldehyde, salicylaldehyde, cinnamaldehyde, glyoxal and mixtures of these aldehydes.
• Particularly preferred organic acids having a pKa in the range of 3 to 5 at 25 ° C are selected from the group consisting of benzoic acid, lactic acid, citric acid, phthalic acid, 2,4-dihydroxybenzoic acid and salicylic acid, wherein benzoic acid, lactic acid, and citric acid more preferred, most preferred is benzoic acid.
• a pH is adjusted in the range of 2.8 to 5, preferably in the range of 3.5 to 4.5, in each case measured at 20 ° C.
• step (S-1) is carried out at a temperature in the range of 90 to 160 ° C, preferably at a temperature in the range of 100 to 150 ° C.
• the total amount of furfuryl alcohol used is at least 50% by weight, preferably at least 55% by weight, and preferably in the range from 60 to 75% by weight, more preferably in the range from 62 to 72% by weight .-%, wherein the weight percentages are based on the total mass of the resulting mixture according to the invention.
• a preferred mixture according to the invention (as defined above), preferably in one of the preferred embodiments, is a mixture preparable by a process according to the invention, preferably in one of the preferred embodiments.
• the refractory molding base material according to the invention (constituent (iii) of a reaction mixture according to the invention) is first coated with the acid hardener (constituent (ii) of a reaction mixture according to the invention).
• the binder ie a mixture according to the invention, component (i) of a reaction mixture according to the invention
• the molding material mixture can then be shaped into a shaped body. Since binder and acid hardener are evenly distributed in the molding material mixture, the curing is largely uniform even with large moldings.
• the curing is preferably carried out in the absence of sulfur dioxide.
• a reaction mixture according to the invention is preferably prepared which then hardens without further ado.
• the remarks on the reaction mixture according to the invention apply correspondingly to the process according to the invention.
• a preferably molding material mixture is used, which is particularly suitable for the production of large casting molds and cores, wherein these casting molds and cores during casting show a reduced emission of defective compounds.
• the invention also relates to a casting mold or a core for producing metal bodies, obtainable by curing a reaction mixture according to the invention, preferably in one of the embodiments characterized as being preferred.
• the invention relates to the use of a mixture according to the invention, preferably in one of the embodiments marked as preferred, as cold-curing binder, preferably as a no-bake binder in the foundry, in particular in the production of metal bodies by means of a casting process, wherein the curing of Binder is preferably carried out without the use of gaseous sulfur dioxide.
• the invention relates to the use of a mixture according to the invention or of a reaction mixture, preferably in each case in one of the preferred embodiments, in a no-bake process for the production of metal bodies, preferably in a no-bake process, in which no gaseous sulfur dioxide is used for curing, preferably in a no-bake process without gassing step.
• Table 1 compares the chemical and physical parameters of the resins. The values given correspond to average values which are typical for the particular binder.
• the non-bake binders of the invention with the designations "KH-Ref1" and "KH-Ref2" are commercially available products.
• Table 1 ⁇ / u> KH-Ref1 KH-Y KH-Ref2 (not according to the invention) (Invention) (not according to the invention)
• Total nitrogen content 1.05% by weight 2.85% by weight 3.5% by weight water content 10% by weight 11% by weight 10% by weight free formaldehyde 0.15% by weight 0.15% by weight 0.06% by weight
• the non-inventive no-bake binder KH-Ref2 which was likewise investigated for comparison purposes, had the following composition: Cold resin TN-X 56.0% by weight Content of monomeric FA 41.3% by weight water 2.5% by weight N-aminopropylmethyldiethoxysilane 0.2% by weight
• Furfuryl alcohol (60.30% by weight), paraformaldehyde 91% (15.88% by weight), formic acid 85% (0.60% by weight), urea (12.59% by weight), Water (3.56% by weight), ethanol (4.95% by weight), ammonia 25% in water (2.12% by weight).
• Furfuryl alcohol (66.98% by weight), paraformaldehyde 91% (12.38% by weight), benzoic acid (1.56% by weight), urea (6.07% by weight), water (6 , 94% by weight), ethanol (2.98% by weight), monoethylene glycol (1.99% by weight), N-aminopropyltriethoxysilane (Dynasilan 1506) (0.40% by weight) sodium hydroxide solution 33% strength in water (0.70% by weight).
• the reactor contents are stirred.
• 223.2 kg of furfuryl alcohol and 5.2 kg of benzoic acid are mixed thoroughly (pH value: 3.7 to 4.2) and then 123.8 kg of paraformaldehyde are added.
• the mixture is then heated to 100 to 110 ° C within 30-60 minutes and held this temperature for 60 minutes.
• two further portions of furfuryl alcohol and benzoic acid are added to the reaction mixture at intervals.
• the temperature is increased to about 135 ° C and the reaction mixture heated under reflux (duration: 3 to 5 hours, the reflux temperature drops slowly and continuously to about 125 ° C).
• the resulting reaction mixture is cooled rapidly, added 60.7 kg of urea and cooled further.
• the production of the molding material mixture was carried out in a laboratory mixer (BOSCH).
• BOSCH laboratory mixer
• the parts by weight of acid hardener specified in Table 2 were added to 100 parts by weight of quartz sand H32 (Quarzwerke Frechen) and mixed for 30 seconds.
• the parts by weight of binder indicated in Table 2 were added and remixed for a further 45 seconds.
• the resulting mixture was prepared at room temperature (18-22 ° C) and a relative humidity (RLF) of 20-55%.
• the sand temperature was 18 - 22 ° C.
• the molding material mixture was introduced by hand into the Ardriegelform and compacted with a hand plate.
• the molding material mixture in a form (cup), 80 mm in height and 80 mm in diameter, compacted with a hand plate.
• the surface is in particular Periods checked with a test nail. If the test nail no longer penetrates into the core surface, the curing time is given.
• the respective flexural strength values were determined in accordance with the above-mentioned VDG leaflet P 72.
• the test bars were placed in a Georg Fischer strength tester equipped with a three-point bending device (DISA-Industrie AG, Schaffhausen, CH) and the force was measured, which resulted in the breakage of the test bars.
• the flexural strengths were after one hour, after two hours, after four hours and after 24 h after the preparation of the test material mixture (storage of the cores after demolding, each at room temperature 18-22 ° C, RLF 20-55%).
• TRGS Technical Rule for Hazardous Substances
• the valuation indices BI AGW were determined in accordance with TRGS 402 point 5.2.
• the valuation indices BI other were determined in accordance with TRGS 402 point 5.3. It was based on the TRGS 402 in the January 2010 issue.
• BI total BI AGW + BI Other. This index should not exceed the limit of 1.
• the mixtures according to the invention allow compliance with the limit BI total.
• the storage stability was stored for a period of 6 months at a constant temperature of 20-22 ° C and examined at monthly intervals.
• the viscosity of the cold resin KH-Y according to the invention was measured and the performance properties of a corresponding molding material mixture determined (as described above).
• a molding material mixture was first prepared. 0.5 parts by weight of a 65% strength by weight solution of p-toluenesulfonic acid in water were first added to 100 parts by weight of quartz sand H32 (Quarzwerke Frechen) and mixed for 30 seconds. Subsequently, 1 part by weight of binder KH-Y was added and remixed for a further 45 seconds. The resulting molding material mixture was prepared at room temperature (20-22 ° C) and a relative humidity (RLF) of 40-55%. The sand temperature was 20 - 22 ° C.
• the mixture according to the invention KH-Y2 has a very low total content of nitrogen, which is why this inventive no-bake binder is particularly suitable for iron and steel casting, especially for stainless steel casting.
• Furfuryl alcohol (70.18 wt%), paraformaldehyde 91% (12.03 wt%), benzoic acid (1.64 wt%), bisphenol A (2.75 wt%), urea ( 1.72 wt.%), Water (5.14 wt.%), Ethanol (3.12 wt.%), Monoethylene glycol (1.00 wt.%), N-aminopropyltriethoxysilane (Dynasilan 1505) ( 0.40 wt%) potassium hydroxide 45% in water (2.02 wt%).
• the reactor contents are stirred.
• 234.0 kg of furfuryl alcohol and 5.5 kg of benzoic acid are mixed thoroughly (pH value: 3.7 to 4.2) and then 120.3 kg of paraformaldehyde are added. It is then heated within 30-60 minutes to 100-110 ° C and held this temperature for 60 minutes. At this temperature, two further portions of furfuryl alcohol and benzoic acid are added to the reaction mixture at intervals. Subsequently, the temperature is increased to about 135 ° C and the reaction mixture heated under reflux (duration: 3 to 5 hours, the reflux temperature drops slowly and continuously to about 125 ° C). Then the resulting Cooled reaction mixture a little, added 27.50 kg of bisphenol A and cooled further.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Mold Materials And Core Materials (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Phenolic Resins Or Amino Resins (AREA)

Priority Applications (1)

Applications Claiming Priority (3)

Related Parent Applications (2)

Publications (3)

Family

ID=45495896

Family Applications (2)

Family Applications Before (1)

Country Status (9)

Families Citing this family (20)

Citations (19)

Family Cites Families (16)

• 2011
  • 2011-12-16 US US13/984,481 patent/US9993863B2/en active Active
  • 2011-12-16 WO PCT/EP2011/073023 patent/WO2012080454A1/fr active Application Filing
  • 2011-12-16 EP EP11808845.9A patent/EP2651581B1/fr active Active
  • 2011-12-16 JP JP2013543807A patent/JP5913359B2/ja active Active
  • 2011-12-16 CN CN201180067862.0A patent/CN103379971B/zh active Active
  • 2011-12-16 TW TW100146988A patent/TWI564317B/zh active
  • 2011-12-16 PL PL18214344T patent/PL3495073T3/pl unknown
  • 2011-12-16 DE DE202011110617.2U patent/DE202011110617U1/de not_active Expired - Lifetime
  • 2011-12-16 EP EP18214344.6A patent/EP3495073B1/fr active Active
  • 2011-12-16 ES ES11808845T patent/ES2746190T3/es active Active
  • 2011-12-16 PL PL11808845T patent/PL2651581T3/pl unknown
  • 2011-12-16 ES ES18214344T patent/ES2816451T3/es active Active

Patent Citations (22)

Also Published As

Similar Documents

Legal Events