EP3727722A1 - Verfahren zur herstellung eines metallischen gussstücks oder eines ausgehärteten formteils unter verwendung aliphatischer polymere umfassend hydroxygruppen - Google Patents
Verfahren zur herstellung eines metallischen gussstücks oder eines ausgehärteten formteils unter verwendung aliphatischer polymere umfassend hydroxygruppenInfo
- Publication number
- EP3727722A1 EP3727722A1 EP18826293.5A EP18826293A EP3727722A1 EP 3727722 A1 EP3727722 A1 EP 3727722A1 EP 18826293 A EP18826293 A EP 18826293A EP 3727722 A1 EP3727722 A1 EP 3727722A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- molding
- molding material
- casting
- acids
- material mixture
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
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- 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
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- 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
- B22C1/2266—Polyesters; Polycarbonates
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/12—Treating moulds or cores, e.g. drying, hardening
Definitions
- the present invention relates to a method (i) for producing a metallic casting or (ii) for producing a cured molding for use in casting metallic castings. Furthermore, the present invention relates to the use of an etherified cross-linked aliphatic polymer comprising hydroxy-containing structural units as a binder of a molding for use in the casting of metallic castings. The present invention also relates to a molding for use in the casting of metallic castings comprising at least one molding base and a cured binder comprising or consisting of an etherified cross-linked aliphatic polymer comprising hydroxy-containing structural units. In addition, the present invention relates to a cured molding, which can be produced by a process according to the invention and a molding material mixture for use in the inventive method.
- Moldings used in metal casting
- cores, molds and feeders including feeder caps and food casings or feeder casings
- a refractory base molding material which, depending on the application, contains one or more refractory solids
- quartz sand, and / or one or more particulate lightweight fillers for example Spheres from fly ash
- suitable binder which gives the molding after removal from the mold (such as a molding box such as a core box or a molding box, see below) sufficient mechanical strength.
- the mixture of molding base material and binder which may optionally contain further additives, is referred to as "molding material mixture”.
- Refractory solids are preferably particulate and in a free-flowing form, so that they, after incorporation into a molding material mixture, in a suitable mold (the mold, see above) can be filled and compacted there.
- Feeders and cores are for this purpose usually introduced into core molds under pressure in a mold, that is, "shot”. Smaller moldings are often shot as well, while larger moldings, especially larger molds, are usually formed in a mold box by pounding. In general, all moldings can also be produced by stamping in appropriate forms, for example by hand molding.
- Moldings such as molds, cores and feeders have to meet various foundry-typical requirements. The nature and extent of the fulfillment of these requirements are essentially determined by the binder used for their preparation:
- a high so-called final strength ie the strength after complete curing of the molded part
- a high temperature resistance of the molded parts in the actual metal casting are important, especially for cores and molds, so that the molded part does not deform under the weight of the cast metal (ie maintains a good dimensional stability during the casting process, also referred to as "cast resistance") and the so produced metal casting can be produced as possible without casting errors.
- the molded parts used have a clean or smooth surface as possible without distortion or the like, since otherwise surface defects of the molded parts can be transferred to the surfaces of the metal castings produced with their help.
- a high resistance of the molded parts against aqueous moisture is of great advantage.
- such a high moisture resistance allows a longer shelf life of the molded parts, even under demanding climatic conditions (warm, humid climates) and ideally over several days or weeks, which facilitates or makes possible the production of molded parts in stock and their storage.
- the industrial production of metal castings with these moldings gains considerable flexibility.
- a water absorption for example, during their storage by absorbing moisture from the air
- a water absorption can lead to the fact that at the high temperatures of the metal casting from corresponding water retention Forming vapor bubbles, which can lead to voids in the metal casting, making it then unusable.
- a high moisture resistance of the molded parts is advantageous because it allows, for example, their use with different sizing types and in particular also with water-based sizing.
- Sizing agents are ceramic-based release agents which, in certain cases, are intended to prevent direct contact between molded parts, for example cores, and the molten metal, so that they can better withstand the high thermal loads during metal casting.
- a molded part should then decompose under the influence of the heat given off by the cast metal as much as possible so that it loses its mechanical strength, ie the cohesion between individual particles of the mold base material is lost.
- the molding then disintegrates again into fine particles of the molding material, which can be easily and without residue removed from the metal casting. If the molding is a core, such advantageous disintegration properties result in particularly good decorability of a metal casting.
- the decomposition of the molding which is usually accompanied by a thermal decomposition of the binder, as possible emission-free, i.
- hot-curing processes after shaping, for example, the molding material mixture is heated to a sufficiently high temperature by the heated mold to expel the solvent contained in the binder and / or to initiate a chemical reaction by which the binder is cured.
- An example of such a hot curing process is the so-called "hot box process”. It is used today mainly in the mass production of cores.
- Cold-curing processes are processes which are carried out essentially without heating the mold used for core production, generally at room temperature or at a temperature caused by a possible, for example, chemical, reaction.
- the curing takes place, for example, by a gas which is passed through the molding material mixture to be cured and thereby triggers a corresponding chemical reaction.
- An example of such a cold-curing process is the so-called "cold-box process", which is now widely used in the foundry industry.
- corresponding inorganic binders which do not or only to a much lesser extent have the abovementioned appearance of the release of undesirable odor or pollutants during metal casting.
- An example of such an inorganic binder is water glass.
- the corresponding molding material mixture consists essentially of mold base material, for example quartz sand, and water glass (as an aqueous solution of alkali metal silicates).
- the molded molding material mixtures are cured, for example by gassing with CO 2 .
- the use of such inorganic binder is associated with other, typical disadvantages: For example, moldings produced from inorganic binders often have only low strengths. This is particularly evident immediately after the removal of the molding from the tool come to light.
- the document DE-OS 26 15 714 relates to molding sand for metal casting.
- Document DE 39 28 858 A1 describes crosslinked hydrogels and processes for their preparation.
- Document US 4487868 relates to foundry core compositions.
- the document DE 10 2007 026 166 A1 relates to a process for the thermoplastic shaping of polyvinyl alcohol and moldings or granules produced therewith.
- the document EP 1 721 689 A1 describes a method for producing a casting.
- Document EP 1 769 860 A1 describes a molding process and molds made by the process.
- the document WO 2008/1 10378 A1 teaches a composition for the production of feeders.
- the document WO 2017/084851 A1 specifies a mold, a process for its production and its use.
- Climatic conditions resulting and / or these can be used with water-based sizes; the lowest possible absorption of heat energy and, ideally, a good thermal insulation effect during metal casting of the molded parts produced by the process; the lowest possible emission of odors and / or pollutants and of smoke or smoke, especially under the conditions of a metal casting of the molded parts produced by the process, both in the casting of light metals and their alloys and in iron and steel casting.
- a binder for a molded part in the casting of metallic castings which has one or more, and in the ideal case, all of the above-mentioned advantageous relevant properties or effects.
- a molded part which one, several and ideally all, the has relevant properties mentioned in connection with the method described above.
- moldings for the foundry industry can be stacked, in particular molds, cores and feeders, which are a multitude of the following have shown advantageous properties.
- feeder in addition to feeders and feeder covers, feeder inserts and feeder caps understood.
- the moldings produced by the process according to the invention have a high final strength (after drying or curing) and a high cast resistance and a high temperature resistance during casting with iron or steel. Striking is also the advantageous smooth and clean surface structure of the moldings produced by the process according to the invention. It was also possible to show that the molded parts produced by the process according to the invention have very good moisture resistance and water resistance, which makes them ideal for longer days or weeks of storage even under difficult climatic conditions (humid and warm climates).
- the molded parts produced by the process according to the invention also show only a small heat energy absorption, resulting in a small voids formation, which only in relatively far away from the actual metal casting areas of the metal casting (approximately in Feeder approach) occurs, precipitates.
- This property makes the process according to the invention particularly suitable for the production of feeders, in particular of insulating feeders.
- the moldings produced by the process according to the invention are also characterized by an extremely advantageous Auspack , as they largely disintegrate due to the heat released during metal casting and thus greatly simplify further processing of the correspondingly produced metal casting, because only a few or, ideally, no post-processing steps on the manufactured metal casting are required.
- a particular advantage of the molded parts produced by the process according to the invention is their emission behavior, especially during metal casting and unpacking of metal castings, which were produced with the help of these inventively manufactured moldings: so are both the metal casting with light metals or their alloys (such as in aluminum casting), as well as iron or steel casting or when unpacking the correspondingly produced metal castings no or hardly smoke or. Smoke, no or hardly occurrence of unpleasant odors and / or no or hardly emissions potentially harmful substances observed as they occur when using conventional, especially aromatic-containing (eg phenolic resin-containing), organic foundry binders regularly occurrences. This applies in particular to feeder produced by the process according to the invention.
- aromatic-containing eg phenolic resin-containing
- the step of combining the molding material with (a) the aqueous mixture comprising one or more aliphatic polymers and (b) with the aqueous mixture comprising one or more acids and / or one or more heat labile acid Precursors can be made to a molding material mixture in any technically possible manner:
- the molding material can first with (a) the aqueous mixture comprising one or more aliphatic polymers combined, preferably mixed, and it can then (after the aforementioned union) (b) the aqueous mixture comprising one or more acids and / or one or more heat-labile acid precursors is combined with the template formed by said combining, preferably mixed therewith.
- the molding base may be combined with (b) the aqueous mixture comprising one or more acids and / or one or more heat labile acid precursors, preferably mixed therewith, and then (after the aforementioned combination) (a ) the aqueous mixture comprising one or more aliphatic polymers is combined with the template formed by said combining, preferably mixed therewith.
- the molding material alternately with fractions of (a) the aqueous mixture comprising one or more aliphatic polymers and (b) the aqueous mixture comprising one or more acids and / or one or more heat-labile acid precursors , preferably to mix.
- a process according to the invention preferably a process (ii) according to the invention, is also preferred, the aqueous mixture comprising one or more aliphatic polymers (a) and the aqueous mixture comprising one or more acids and / or one or more heat-labile acids.
- Precursors (b) are provided or manufactured by
- the abovementioned aqueous binder system to be used in the process according to the invention preferably comprises one or more aliphatic polymers each comprising hydroxyl-containing structural units of the formula (I) in a total amount in the range of 10% by weight to 40% by weight, particularly preferably in the range of 15 Wt .-% to 35 wt .-% and most preferably in the range of 20 wt .-% to 30 wt .-%, based on the total mass (or the total weight) of the aqueous B by ittelsys- system.
- the aforesaid aqueous binder system to be employed in the process of the invention comprises one or more acids and / or one or more heat labile acid precursors in a total amount in the range of 0.2% to 10% by weight, more preferably in the range of 0.3 wt .-% to 5 wt .-% and most preferably in the range of 0.4 wt .-% to 2.5 wt .-%, based on the total mass (or the total weight) of the aqueous binder system.
- the abovementioned aqueous binder system to be used in the process according to the invention comprises, in addition to the abovementioned constituents, one or more aliphatic polymers, each comprising structural units containing hydroxyl groups of the formula (I) and one or more acids and / or one or more heat-labile acid precursors as further constituent only water, so that the constituents contained therein: one or more aliphatic polymers in each case comprising hydroxyl-containing structural units of the formula (I), one or more acids and / or one or more heat-labile acid precursors and water in this preferred variant in each case to 100 wt .-% complete.
- aqueous mixture comprising one or more aliphatic polymers (a), aqueous mixture comprising one or more acids and / or one or more heat labile acid precursors (b) and / or binder system with each other ( as indicated above) can be carried out in a manner known to those skilled in the art with a stirrer suitable for this purpose.
- an aqueous mixture comprising one or more aliphatic polymers (a) having a high dynamic viscosity is used, such a high-viscosity aqueous mixture (a) is preferably either first combined with the molding material (and this premix is then mixed with the aqueous mixture comprising one or more acids and / or one or more heat-labile acid precursors (b) combined) or combined with a premix which comprises combining the molding material with (b) the aqueous mixture comprising one or more acids and / or one or more heat-labile acid precursors were obtained as described above.
- a premix of the aqueous mixture comprising one or more aliphatic polymers (a) by combining with the aqueous mixture comprising one or more acids and / or one or more heat labile acid precursors (b), for example to a binder system as indicated above is present
- this premix or this binder system is processed further immediately after its or its preparation according to the method according to the invention: a storage of such a premix or of such a binder system over a longer period
- periods of time may lead to deterioration of quality if such a premix or binder system contains free acid or free acids.
- Preparing a premix of the aqueous mixture comprising one or more aliphatic polymers (a) by combining with the aqueous mixture comprising one or more heat labile acid precursors (b), but not comprising one or more acids (b), for example to one given above Binder system is therefore also preferred if this premix is not provided immediately after its preparation for further processing according to the inventive method, since a storage of such a premix or such a binder system containing no free acid or acids, even for long periods readily and without or without significant loss of quality of the premix or the binder system is possible.
- the aqueous mixture to be used in the process according to the invention comprising one or more aliphatic polymers each comprising hydroxyl-containing structural units of the formula (I) comprises the one or more aliphatic polymers in a total amount (concentration) in the range of 10 wt .-% to 40 wt. %, more preferably in the range of 15 wt .-% to 35 wt .-% and most preferably in the range of 20 wt .-% to 30 wt .-%, based on the total mass (or the total weight) of the aqueous mixture comprising one or more aliphatic polymers.
- the aqueous mixture to be used in the process according to the invention comprising one or more acids and / or one or more heat-labile acid precursors comprises the one or more acids and / or the one or more heat-labile acid precursors in a total amount (concentration) in the range from 0.2% by weight to 10% by weight, more preferably in the range from 0.3% by weight to 5% by weight and most preferably in the range from 0.4% by weight to 2, 5 wt .-%, based on the total mass (or the total weight) of the aqueous mixture comprising one or more acids and / or one or more heat labile acid precursors.
- the partial step of heating the molded molding material mixture upon curing of the molded molding material mixture to the cured molding carried out so that decompose existing in the molding mixture heat-labile acid precursors by the action of heat to release acid, if such heat-labile acid precursors are used in the process according to the invention.
- the acids liberated in this way then also act as corresponding, (at least partially etherifying) crosslinking acids in the partial step of heating the shaped molding material mixture during curing of the molded molding material mixture to the cured molding.
- the molding material mixture is cured particularly comprehensive to the cured molded part, so that the above-mentioned advantageous properties of such a molding result, in particular its good moisture resistance or its good water resistance.
- Formstoffmischung before or during molding of the molding material mixture is adjusted so that a moldable to a molding, preferably to a feeder or a core, and / or to a molding, preferably to a mold, stampable molding mixture results; and or the step of curing the molded molding material mixture by heating the shaped molding material mixture and removing water from the heated, molded molding mixture is carried out at least until a water-resistant, preferably a completely waterproof, cured molding results, preferably at a temperature in the range from 100 to 300 ° C, preferably in the range of 150 to 250 ° C, more preferably in the range of 180 to 230 ° C; and or
- the molding of the molding material mixture by firing preferably in a shooting machine, or by introducing into a molding box takes place, and / or
- the molding material mixture comprises a sand, preferably a sand selected from the group of sands consisting of quartz sand, zircon sand, olivine sand, chromite sand, mullite sand and mixtures thereof, and a solids content of more than 95 wt .-%, based on the total mass of the molding material mixture , and or
- molding tool designates any tool used in the foundry industry for shaping molded parts, preferably selected from the group consisting of casting mold, core and feeder (including feeder caps and feeder sleeves), in particular molding boxes and shooting machines for Shooting of molded parts, in particular cores and feeders, including core shooters.
- molding box includes any tool which is suitable for molding a foundry molding selected from the group consisting of mold, core and feeder (including feeder caps and feeder sleeves), in particular molding boxes and core boxes.
- the total moisture content of the molding material mixture is understood as meaning the total content of the molding material mixture in liquid (ie in liquid form, less solids dissolved therein), constituents added to the mold base or combined with the molding material, expressed in terms of weight percent on the total mass (or the total weight) of the molding material mixture.
- the total moisture content of the molding material mixture includes the total water content and additionally the content of further liquid added components, if present, such as acid or acids added in liquid form.
- the total content of the molding material mixture in the context of the present invention is understood as meaning the total content of the molding material mixture added to the molding material or combined with the molding material (less solids dissolved therein), stated in percent by weight based on the total mass (or mass). the total weight) of the molding material mixture.
- the total moisture content, preferably the total water content, of the molding material mixture may be adjusted before or during the molding of the molding material mixture, for example by correspondingly a greater or lesser volume of one or more of the aqueous constituents of the molding material mixture (which are (a) the aqueous mixture comprising one or more aliphatic polymers, (b) the aqueous mixture comprising one or more acids and / or one or more heat labile acid precursors and, if present, the aqueous binder system) is combined with the molding base, the concentrations of the each of the aqueous constituents of the molding material mixture has been appropriately modified by the person skilled in the art or can be fitted, so that in any case, the required or required to form the molding mixture total amounts of one or more aliphatic polymers or to one or more acids and / or one or more heat-labile acid precursors are used.
- Too low a total moisture content or total water content of the molding material mixture can be adjusted by adding suitable amounts of water to an appropriate value.
- the person skilled in the art can adjust both the concentrations of the abovementioned aqueous mixtures (or of the aqueous binder system) and the total moisture content, preferably the total water content, of the molding material mixture before or during molding of the molding material mixture (also by Vari - technik of amount and type of mold base material to be used in relation to the used aqueous constituents of the molding material mixture) with his expertise easily accomplish, so that one to a molding, preferably to a feeder or a core, shootable and / or to a molding, preferably to a mold, stampable molding material mixture results.
- the total moisture content, preferably the total water content, of the molding material mixture must not be so high that a molding compound mixture that is not sufficiently dimensionally stable, too soft or even deliquescent for firing (in particular in a molded part shooting machine) or for stomping results ,
- the total moisture content, preferably the total water content, of the molding material mixture must also not be so low that the particles of the particulate mold base material are not sufficiently dimensionally stable in a mold for firing (in particular in a core shooting machine) or for stamping cohesive molding material mixture present.
- the exemplary embodiments given in the present text give the person skilled in the art further indications as to how a total moisture content, preferably total water content, suitable for the process according to the invention must be selected for the production of the molding material mixture to be used in the process according to the invention.
- a total moisture content preferably total water content
- the inventive method can be used advantageously for the production of various moldings (molds, cores and feeders) and with the usual tools in the foundry industry be performed.
- the inventive method can thus be integrated into the usual, already existing operational processes, so that no or no significant changes in equipment or process in the foundries are needed.
- the term "dimensionally stable molding material mixture” preferably means that such a dimensionally stable molding material mixture after molding the molding material mixture (in particular in a molding tool selected from molding box, core box and corresponding tools as components of a shooting machine) and removing the molding tool by maintaining the shape adopted (for example at 20 ° C and normal pressure) for at least 30 minutes without, for example, deliquescing or disintegrating.
- the step of curing the shaped molding material mixture by heating the shaped molding material mixture and removing water from the heated molded molding mixture as set forth above is carried out until a water resistant (preferably continuous waterproof) cured molding results, preferably one such as this Text specified temperature in the range of 100 to 300 ° C or at a preferred temperature in the range of 150 to 250 ° C, more preferably in the range of 180 to 230 ° C.
- a water resistant (preferably continuous waterproof) cured molding results, preferably one such as this Text specified temperature in the range of 100 to 300 ° C or at a preferred temperature in the range of 150 to 250 ° C, more preferably in the range of 180 to 230 ° C.
- the particular time to be chosen for carrying out the process until a water-resistant (or continuously water-resistant) cured molding is obtained depends primarily on the dimensions of the molding to be produced, in particular its wall thickness or volume.
- smaller moldings such as feeder or feeder caps can already be hardened after about 60 s to 90 s under the conditions of the process according to the invention waterproof (or consistently waterproof), while larger moldings such as large cores or molds only after long periods of, for example, several minutes , After about 30 minutes, under the conditions of the method waterproof (or consistently waterproof) are cured.
- waterproof or consistently waterproof
- the skilled person can by his expertise and the additional information in the present text, very simply select the precise process conditions suitable for the purposes of a particular molding, in particular process durations. If necessary, appropriate simple preliminary tests to determine the appropriate parameters can be performed.
- water-hardened molded part means in this context and in the context of the present invention preferably such a molded part produced by the process according to the invention, which after just complete immersion (ie just complete immersion for the entire period of 30 min) in deionized Water at 20 ° C and atmospheric pressure for a period of 30 min (stopwatch) remains dimensionally stable and does not (even when removed from the water) decays, which here preferably means a disintegration without additional external force.
- waterproof molded parts in which immediately after this immersion test (under the abovementioned conditions) with a core hardness tester GM-578 (Simpson Technologies GmbH, Switzerland) a penetration depth (according to the manual of the core hardness tester) of not more than 4 mm, preferably not more than 3 mm.
- a penetration depth according to the manual of the core hardness tester
- continuously waterproof cured molding refers in this context and in the context of the present invention, in particular such a molded part produced by the process according to the invention, in which all internal volume areas (ie such volume areas that do not adjoin the outer surface of the molding) waterproof cured (as defined above). Such internal volume areas are for the purposes of verification e.g. accessible by sawing.
- the method according to the invention is carried out according to the above-mentioned preferred embodiment at least until a water-resistant, preferably a completely water-resistant, cured molding results.
- a water-resistant, preferably a completely water-resistant, cured molding results under the selected conditions of the process according to the invention, the curing is preferably no longer continued by heating the shaped molding material mixture and removing water from the heated molded molding mixture.
- molding of the molding material mixture takes place by casting, preferably in a shooting machine such as a core shooting machine, or by introducing the molding material mixture into a molding box and preferably stamping the molding material mixture in the molding box.
- a shooting machine with heatable molding box such as a core shooter with heatable core box, as it is known per se for use in the processing of hot-box binders or thermosetting water glass binders.
- a shooting machine also has a device for flowing through the molded molding material mixture with gas, preferably with warm or hot air.
- the molding material mixture shot with such a shooting machine can then be heated in the heatable molding box (for example core box), heated (by heating and / or flowing through warm or hot air) and removing water (for example by passing it through warm or hot air). preferably waterproof) cured molding.
- a shot molding material mixture can also be cured in another way, for example (together with the molding tool) in a drying oven, to form the (preferably waterproof) cured molding.
- the most suitable type of shaping can be selected by the person skilled in the art on the basis of the circumstances of the individual case.
- the molding material mixture for the production of smaller molded parts such as feeder or serkappen or smaller cores or shapes, advantageously shot in a shooting machine, particularly preferably in a core shooting machine.
- Larger molded parts for example, larger cores or larger shapes are advantageously formed by introducing the corresponding molding material mixtures in a molding box (or core box) and preferably compacted by stamping.
- the molded molding material mixture is preferably cured in the core box or molding box containing it to form the (preferably waterproof) cured molding.
- Foaming or bubbling in the molding material mixture is preferably avoided when carrying out the process according to the invention, preferably in the step of combining the molding material with (a) the aqueous mixture comprising one or more aliphatic polymers and (b) with the aqueous mixture comprising one or more acids and or one or more heat-labile acid precursors, to a molding material mixture "and / or in the step” shaping the molding material mixture ", preferably by minimizing or possibly avoiding the introduction of air or other gases in one or both of these steps.
- Some aliphatic polymers comprising hydroxy-containing structural units of formula (I) may tend to foam or bubble; However, such foaming or blistering is not desired in the manufacture of a cured molding for use in casting metallic castings by the process of the present invention, for example, because a foam or blister-containing molding material mixture has a porous structure when cured to the cured molding, thereby achieving the desired Strength and / or heat resistance of the resulting molded article can be impaired.
- the removal of water from the heated molded molding material mixture is accomplished by one or more measures selected from the group consisting of Passing a heated gas, evacuating and drying in a dryer, preferably by passing a heated gas, more preferably by passing heated air through it.
- the above-mentioned drying apparatus is preferably selected from the group consisting of drying oven, circulating air drying oven, belt dryer, continuous dryer, tunnel dryer and drying belt.
- the drying device is a circulating air drying oven.
- the moldings produced by the process according to the invention can be cured particularly well and in a relatively short period of time (preferably waterproof), so that advantageously short cycle times in the production of these moldings are possible, the moldings here but not by excessive heating again their advantageous properties (see above) lose all or part.
- the removal of water from the shaped molding material mixture according to the method of the invention can be carried out particularly efficiently and advantageously combined with the heating of the molding mixture by passing it through the shaped molding mixture of a heated gas, preferably heated air. In this way, the molded molding material mixture is particularly quickly and completely cured - even in its interior - to the cured molding.
- the setting of the precise process parameters for curing the molded molding material mixture to the cured molding for example, the duration of the heating, the temperature of the drying oven or the heated gas, the flow time with heated gas (ie, the duration of the passage of the heated gas) and the pressure of the heated gas (if used) to a great extent depending on the geometric dimensions of the molded part to be produced by curing (such as its Size), its weight, its volume and / or its wall thicknesses.
- aliphatic polymers used can be prepared by at least partial saponification of polyvinyl acetate, and / or - in containing aqueous mixture are dissolved, preferably at least 90 wt .-%, more preferably at least 95 wt .-%, based on the total mass (or the total weight) of aliphatic polymers used.
- %) preferably determined according to the method as indicated in document DE 10 2007 026 166 A1, paragraphs [0029] to [0034], and most preferably has a degree of hydrolysis in the range from 70 mol% to 100 mol%, especially preferably in the range of 80 mol% to 100 mol%, preferably determined according to the method according to DIN EN ISO 15023-02 2017- 02 Draft, Annex D, and / or has a dynamic viscosity in the range from 0.1 to 30 mPa ⁇ s, preferably in the range from 1, 0 to 15 mPa ⁇ s, particularly preferably in the range from 2.0 to 10 mPa ⁇ s, in each case determined at a 4% -igen (w / w) aqueous solution of the totality of the polyvinyl alcohols used at 20 ° C according to DIN 53015: 2001-02.
- the abovementioned one or more aliphatic polymers in particular the one or more polyvinyl alcohols indicated above as being preferred, contribute substantially to the advantageous properties of the molded parts produced according to the invention when they are processed by the process according to the invention, in particular to the good moisture resistance or water resistance, ultimate strength and cast resistance of the molded parts according to the invention.
- the above-mentioned one or more aliphatic polymers in particular the one or more polyvinyl alcohols given above as preferred, contribute significantly or even cause the advantageous emission properties of the molded parts produced according to the invention (possibly because the present invention) aliphatic polymers to be used contain no aromatic constituents such as phenolic resins, which are frequently cited as the cause of harmful emissions), in particular for the low or complete lack of emission of smoke or smoke and / or odors and / or pollutants during or after the Metal casting and the low or complete absence of emissions of odors and / or pollutants during the production or storage of the molded parts.
- the one or more aliphatic polymers to be used according to the invention are therefore preferably free from aromatics-containing and / or phenolic resin-containing constituents and / or other constituents which under the conditions of the process according to the invention to a considerable extent smoke, smoke, odor and / or pollutant emissions cause.
- the process according to the invention is preferably not carried out in the presence of aromatic-containing and / or phenolic-containing organic compounds, or the molding material mixture prepared in the process according to the invention is free of aromatic compounds and / or free of phenolic resin (ie
- the molding compound mixture produced according to the invention preferably contains no aromatics-containing organic compounds such as phenolic resins).
- the process of the invention is not carried out in the presence of furan-containing organic compounds or contains the molding material mixture prepared in the process according to the invention no furan-containing organic compounds.
- the process according to the invention is not carried out in the presence of alkoxysilyl compounds, or the molding material mixture prepared in the process according to the invention contains no alkoxysilyl compounds.
- the mold base comprises: one or more particulate refractory solids selected from the group consisting of
- Oxides, silicates and carbides each comprising one or more elements selected from the group consisting of Mg, Al, Si, Ca, Ti, Fe and Zr;
- One or more particulate light fillers preferably selected from the preferred group consisting of
- Core-shell particles preferably comprising a glass core and a refractory shell, more preferably having a bulk density in the range of 470 to 500 g / L, preferably as described in document WO 2008/1 13765;
- Spheres preferably spheres of fly ash
- Composite particles preferably as described in or as produced according to document WO 2017/093371 A1;
- Perlite preferably expanded perlite, more preferably closed-cell microspheres of expanded perlite, preferably as described in document WO 2017/174826 A1;
- Rice husk ash preferably as described in document WO 2013/0141 18 A1;
- the aforementioned one or more particulate refractory solids may be used singly or in combination with each other to form the molding base to be used.
- the abovementioned one or more particulate lightweight fillers can be used individually or in combination with one another and thus form the molding base material to be used.
- the one or more particulate refractory solids can be used in combination with the one or more particulate lightweight fillers as mold base and thus form the mold base to be used.
- the person skilled in the art selects the respectively suitable molding base material.
- quartz sand can be chosen as the basic molding material.
- a mixture of quartz sand with one or more particulate light fillers can be selected for producing a feeder, or only one or more particulate light fillers can be chosen for this, preferably selected from the above-defined, preferred group of light fillers.
- the molding material to be used in the process according to the invention may contain further, preferably particulate, constituents, preferably selected from the group consisting of elemental metals (for example aluminum), oxidizing agents or oxygen sources, preferably metal oxides, particularly preferably oxides of manganese and / or iron, and igniters.
- elemental metals for example aluminum
- oxidizing agents or oxygen sources preferably metal oxides, particularly preferably oxides of manganese and / or iron
- igniters preferably aluminum oxides, particularly preferably oxides of manganese and / or iron
- the starting material to be used may contain aluminum, iron oxide, an oxidizing agent known per se for this purpose, Spheres and in itself known ignition agent for this purpose.
- the total mass of mold base used is in the range from 1: 100 to 50: 100, preferably in the range from 1, 5: 100 to 40: 100, particularly preferably in the range from 2: 100 to 35: 100; and / or the ratio of the total mass of acids used and / or heat-labile acid precursors to the total mass of aliphatic polymers used in the range from 1: 5 to 1:50, preferably in the range from 1:10 to 1:50, more preferably in the range from 1:20 to 1:40 and most preferably in the range from 1:25 to 1:35, lies.
- the setting of the abovementioned (numerical) ratio of the sum of the total mass of the aqueous mixture used comprising one or more aliphatic polymers (a) and the total mass of the aqueous mixture comprising one or more acids and / or one or more heat-labile acid Precursors (b) to the total mass of mold base material used are - as stated above - preferably carried out so that a moldable to a molding, preferably to a feeder or a core, and / or to a molding, preferably to a mold , stampable, preferably dimensionally stable, molding material mixture results.
- an aqueous mixture comprising one or more aliphatic polymers (a) or an aqueous mixture comprising one or more acids and / or one or more heat-labile acid precursors (b), which in each case has a preferred total amount given above, is preferably used one or more aliphatic polymers (a) or on one or more acids and / or one or more heat-labile acid precursors (b).
- the suitable numerical ratio given above is usually in the higher range (ie closer to the upper limit of 50) : 100, preferably 40: 100 and more preferably 35: 100) in cases where a molding material having a lower bulk density (such as quartz sand) is used, while the above-indicated suitable ratio tends to be in the lower range (ie, closer to the lower limit) - limit of 1: 100, preferably 1, 5: 100 and more preferably of 2: 100) is in cases where a molding material with a higher bulk density (such as quartz sand) is used.
- the ratio of the total mass of acids used (or to be used) and / or heat-labile acid precursors to the total mass of aliphatic polymers used is according to the invention at relatively low numerical values, ie there is a relatively low total mass of acids used or to be used and / or or heat labile acid precursors relative to the total weight of aliphatic polymers employed.
- the one or more acids to be used according to the invention and / or the one or more heat-labile acid precursors are preferably free of aromatic-containing constituents, such as phenolic resins and / or other constituents which, under the conditions of the process according to the invention, are smoke, smoke, Cause significant odor and / or pollutant emissions.
- inorganic, preferably water-soluble, proton acids which have a pKa value ⁇ 7, preferably a pKa value ⁇ 5, particularly preferably a pKa value
- Organic proton acids preferably monoprotic organic protic acids, which have a pKa value ⁇ 7, preferably a pKa value ⁇ 5, and are particularly preferably selected from the group consisting of methanesulphonic acid, formic acid, acetic acid, lactic acid and ascorbic acid,
- Lewis acids preferably water-soluble Lewis acids, more preferably selected from the group consisting of boron trifluoride and the chlorides and bromides of boron, aluminum, phosphorus, antimony, arsenic, iron, zinc and tin, and - thermally decomposable to acid salts (ie heat labile acid precursors), preferably selected from the group consisting of
- Ammonium salts of mineral acids such as NH4NO3, preferably NH4Cl, - sulfates and chlorides 3-valent metal ions, preferably FeCß, ALCH, Fe2 (N03) 3, Al 2 (N0 3) 3, Fe 2 (S04) 3 and Al 2 (S04) 3 and
- Sulfuric acid salts of alkanolamines preferably of monoethanolamine.
- proton acids are compounds which are to be regarded as acids according to the acid-base concept of Brönstedt and Lowry.
- monoprotic organic acids refers to those organic acids which have just one group which can provide a proton (H + -lon) in the presence of water, for example a carboxyl group or a sulfonic acid group ,
- the aforementioned inorganic, preferably water-soluble, proton acids are preferably selected from the group consisting of phosphoric acid (including its condensates such as pyrophosphoric acid and metaphosphoric acids), esters of phosphoric acid, boric acid, esters of boric acid, sulfuric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid and nitric acid particularly preferably selected from the group consisting of phosphoric acid, esters of phosphoric acid, sulfuric acid, hydrobromic acid and hydroiodic acid.
- the one or more acids and / or the one or more heat labile acid precursors are selected from the group consisting of:
- inorganic, preferably water-soluble, proton acids which have a pKa value ⁇ 7, preferably a pKa value ⁇ 5, particularly preferably a pKa value ⁇ 3, and organic proton acids, preferably monoprotic organic protic acids, which have a pKs value ⁇ 7, preferably a pKs value ⁇ 5, and particularly preferably selected from the group consisting of methanesulfonic acid, formic acid, acetic acid, lactic acid and ascorbic acid,
- the one or more acids and / or the one or more heat-labile acid precursors are particularly preferably selected from the group consisting of: - inorganic, preferably water-soluble, protic acids which have a pKs
- Value ⁇ 5 preferably have a pKs value ⁇ 3
- - proton organic proton acids which have a pKa value ⁇ 5, and are preferably selected from the group consisting of methanesulfonic acid, formic acid, acetic acid, lactic acid and ascorbic acid.
- phosphoric acid including its condensates such as pyrophosphoric acid and metaphosphoric acids
- sulfuric acid from the group consisting of phosphoric acid (including its condensates such as pyrophosphoric acid and metaphosphoric acids) and sulfuric acid.
- the abovementioned monoprotic organic protic acids which have a pKa value ⁇ 5
- the ratio of the total mass of acids used to the total mass of aliphatic polymers used must be higher (approximately in the range 1) : 5 to 1:10) than when using inorganic and mono-protonic organic acids each having a pKa ⁇ 5 and preferably a pKa ⁇ 3.
- Sulfuric acid has proved to be a particularly preferred acid for use in the process according to the invention, apparently because it has a particularly suitable acid strength for catalyzing the etherification of the hydroxyl groups of the aliphatic polymer (s).
- a process according to the invention specified above preferably a process (i) according to the invention (or a preferred process according to the invention described in this text), has the following additional step:
- the casting metal is at least partially and preferably completely liquid when contacting the cured molding.
- Cast metal is any castable metal or castable metal alloy, in particular light metals and their alloys, such as aluminum, magnesium, tin and zinc; as well as iron and steel.
- the aforementioned preferred process variant (i) is particularly suitable for the production of metallic castings, wherein the casting metal is a light metal or a light metal alloy: Namely It is known that at the relatively low temperatures prevailing in light metal castings (compared to the temperatures of iron or steel castings), conventional, currently widely used, cold box binders are often incompletely thermally decomposed, so that just in these cases - Both during metal casting and when unpacking the molds - a particularly strong formation of smoke, smoke or soot as well as a strong release of gaseous, aromatic-containing emissions occur, which are usually of unpleasant odors are accompanied and are potentially harmful to human health.
- the casting metal is selected from the group consisting of aluminum, magnesium, tin, zinc and their alloys and / or
- the temperature of the cast metal during casting is not higher than 900 ° C and preferably the temperature of the cast metal during casting in the range of 600 ° C to 900 ° C.
- an inventive method (ii) above for producing a hardened feeder, for use in casting metallic castings (or a preferred method of the invention described herein) wherein the mold base comprises: one or more particulate lightweight fillers, preferably selected from the
- Core-shell particles preferably comprising a glass core and a refractory shell, particularly preferably having a bulk density in the range from 470-500 g / L, preferably as described in document WO 2008/1 13765;
- Spheres preferably spheres of fly ash
- Composite particles preferably as described in or as produced according to document WO 2017/093371 A1;
- Perlite preferably expanded perlite, more preferably closed-cell microspheres of expanded perlite, preferably as described in document WO 2017/174826;
- one or more particulate refractory solids selected from the group consisting of
- Oxides, silicates and carbides each comprising one or more elements selected from the group consisting of Mg, Al, Si, Ca, Ti, Fe and Zr;
- the present invention also relates to the use of an etherified, crosslinked aliphatic polymer, in each case comprising hydroxyl-containing structural units of the formula (I)
- -CH 2 -CH (OH) - (I) preferably a corresponding (at least partially) crosslinked polyvinyl alcohol, as a binder of a molded part selected from the group consisting of mold, core and feeder, in the casting of metallic castings.
- the present invention further relates to a molded part selected from the group consisting of mold, core and feeder, for use in the casting of metallic castings, (the molding) comprising: at least one (preferably particulate) molding base and a cured binder comprising or consisting of a through Etherification crosslinked aliphatic polymer, each comprising comprising hydroxyl-containing structural units of the formula (I)
- Total mass of starting material used is in the range from 0.2: 100 to 13: 100, preferably in the range from 0.3: 100 to 10: 100, more preferably in the range from 0.5: 100 to 9: 100.
- the explanations given above for the process according to the invention and for the use according to the invention apply correspondingly, and vice versa.
- the hydroxyl groups of the crosslinking polymer no longer exist (at least predominantly) after the crosslinking carried out by etherification, but are (at least predominantly) involved in the formation of ether groups.
- the cured binder is a water-hardened binder (as defined above), more preferably a fully water-hardened binder (as defined above).
- the present invention also relates to a cured molding selected from the group consisting of mold, core and feeder, prepared or preparable by a process (ii) according to the invention (or a preferred process according to the invention described hereinbefore).
- the present invention also relates to a, preferably aromatic-free and / or phenolic resin-free, molding material mixture for producing a cured molded part selected from the group consisting of mold, core and feeder, for use in the casting of metallic castings comprising (ie In addition to the constituents listed below, further constituents may also be present) or consisting of (ie, in addition to the constituents listed below, no further constituents may be present): at least one (preferably particulate) molding material,
- inorganic, preferably water-soluble, proton acids which have a pKa value ⁇ 7, preferably a pKa value ⁇ 5, particularly preferably a pKa value ⁇ 3,
- monoprotic organic protic acids which have a pKa value ⁇ 7, preferably a pKa value ⁇ 5, and are particularly preferably selected from the group consisting of methanesulfonic acid, formic acid, acetic acid, lactic acid and ascorbic acid, Lewis acids, preferably water-soluble Lewis acids, more preferably selected from the group consisting of boron trifluoride and the chlorides and bromides of boron, aluminum, phosphorus, antimony, arsenic, iron, zinc and tin, and thermally decomposable to acids salts (heat-labile acid Precursors), preferably selected from the group consisting of
- the molding base material comprising or consisting of: - One or more particulate light fillers, preferably selected from the group consisting of
- Core-shell particles preferably comprising a glass core and a refractory shell, more preferably having a bulk density in the range of 470-500 g / L, preferably as described in document WO
- Spheres preferably spheres of fly ash
- Composite particles preferably as described in or as produced according to document WO 2017/093371 A1;
- Perlite preferably expanded perlite, more preferably closed-cell microspheres of expanded perlite, preferably as described in document WO 2017/174826;
- Rice husk ash preferably as described in document WO 2013/0141 18; - expanded glass,
- Oxides, silicates and carbides each comprising one or more elements selected from the group consisting of Mg, Al, Si, Ca, Ti, Fe and Zr, Mixed oxides, mixed carbides and mixed nitrides, each comprising one or more elements selected from the group consisting of Mg, Al, Si, Ca, Ti, Fe and Zr, and - graphite.
- the above-mentioned molding material mixture according to the invention (or a preferred molding material mixture according to the invention specified above) is suitable and intended for use in the abovementioned process according to the invention.
- FIG. 1 shows the remainders of a comparison standard bending seal "B-Cold
- Fig. 2 shows the remnants of a comparative standard bending seal "B-V38" in an iron casting after casting. It can be seen that the remains of the standard bending bolt "B-V38" were well and almost completely removed from the iron casting (good decorability, see Example 7).
- Fig. 3 shows the remains of a standard bending strip "B-E61.3V1" produced by the process according to the invention in an iron casting after casting. It can be seen that the remains of the standard bending seal "B-E61.3V1" were very good and almost completely removed from the iron casting (very good decorability, see Example 7).
- FIGS. 4 to 9, described below, show cross-sections of a sliced iron casting, which is sawn in the middle (along the bearing surfaces of the standard bending bars), so that the cavities produced by standard bending bars in the iron casting (after their removal from the cast iron piece) in the cast iron piece are divided into two halves lengthwise in the middle (for more details see Game 7).
- the cross sections of the cavities (casting negatives) produced by the standard bending bars are thus half each in the upper half of the sawed metal cast piece (produced by the part of the standard bending seal, "upper mold half") located at the top of the iron casting and in the lower half of the sawn metal cast piece (produced by the lower part of the standard bend, "lower half" of the cast iron).
- Fig. 4 shows in cross section the upper mold half of the iron casting. This shows the upper half of the cavity formed by the standard bending seal B-V38 (comparison) after removal from the metal casting (casting negative). From the straight wooden spatula placed on this top of the casting negative, it can be seen that the casting negative in the center has a distinct concave deformation (away from the wooden spatula) caused by the deformation of the standard bending seal B-V38 during casting with iron. Cores that are not dimensionally stable during casting can not be used in the production of metal castings.
- Fig. 5 shows in cross section the lower mold half of the iron casting. It shows the lower half of the cavity formed by the standard bending seal B-V38 (comparison) after removal from the metal casting (casting negative).
- the casting negative on each side has clearly visible concave (away from the wooden spatula) deformations caused by the deformation of the standard bending seal B-V38 during casting with iron.
- Fig. 6 shows in cross section the upper mold half of the iron casting. This shows the upper half of the cavity formed by the standard bending seal B-cold box (comparison) after removal from the metal casting (casting negative).
- Fig. 7 shows in cross section the lower mold half of the iron casting. It can be seen in the lower half of the resulting by the standard bending B-cold box (comparison) after its removal from the metal casting cavity (casting negative).
- Fig. 8 shows in cross section the upper mold half of the iron casting. It can be seen in the upper half of the resulting by the standard bending B-E61.3V1 (produced by a process according to the invention) after its removal from the metal casting resulting cavity (casting negative). It can be seen from the straight wooden spatula applied to this upper side of the casting negative that the casting negative has no visible deformations and therefore the standard bending seal B-E61.3V1 has not visibly deformed during casting with iron. In comparison to FIGS. 6 and 7, a significantly lower mineralization is also discernible.
- Fig. 9 Fig. 9 shows in cross section the lower mold half of the iron casting.
- Fig. 10 shows in cross section an iron cube (module 1, 68 cm) obtained by using a cold-box-bound feeder, which has been produced by trial-casting, not according to the invention, with a top view of the iron remanent feeder. It can be seen a significant void formation in the residual feeder, which extends into the metallic casting (iron cube).
- Fig. 11 shows in cross-section an iron cube (module 1, 68 cm) obtained by using a water glass-bound feeder which has not been produced in accordance with the invention (module 1, 68 cm) with a top view of the remainder of the feeder made of iron. There is a clear voids formation in the residual feeder, which reaches far into the metallic casting (iron cube).
- Figure 11 see Example 13.
- FIG. 12 shows in cross-section a iron cube (module 1, 68 cm) obtained by trial and error using a feeder ("Speiser-B-E68.4") produced according to the invention with an approach of the residual feeder of iron recognizable above. There is no voids formation in the metal casting (iron cube) to recognize, voids appear only in the residual feeder.
- a feeder Seiser-B-E68.4"
- the basic molding material used was quartz sand BO 42 (CAS No. 014808-60-7) from Bodensteiner Sandwerk GmbH & Co. KG.
- the aqueous PVAL mixture used was a 25% strength by weight solution of polyvinyl alcohol (> 93% polyvinyl alcohol) having a degree of hydrolysis of about 88 mol% and a dynamic viscosity in the range from 3.5 to 4.5 mPa s ( measured as 4% strength by weight aqueous solution at 20 ° C. according to DIN 53015), methanol content ⁇ 3% by weight; CAS RN 25213-24-5, Kuraray.
- aqueous sulfuric acid mixture a 36.5% by weight aqueous solution of sulfuric acid, CAS RN 7664-93-9, was used.
- the cold-box activator 6324 used was a polyisocyanate customary for the preparation of cold-box binders (benzyl ether-based polyurethane resin) (activator 6324 from Hutten-Albertus Chemische Werke GmbH).
- the cold box gas resin 7241 used was a phenolic resin customary for the preparation of cold box binders (polyurethane resin based on benzyl ether) (gas resin 7241 from Wilsontenes-Albertus Chemische Werke GmbH).
- the molding material mixtures were prepared as indicated below: F-Cold-Box molding material mixture: the constituents mentioned in Table 1 were mixed in an electric mixer (Bosch Profi 67) to form a moldable mixture which can be molded or stamped into a molded part.
- the molding compound mixture cold box is a non-prepared by the novel process molding composition for comparison purposes.
- Mixture F-V38 the ingredients listed in Table 1 were mixed together in an electric mixer (Bosch Profi 67), forming a moldable mixture which can be molded or stamped into a molded part.
- the molding material mixture V38 is a molding material mixture not prepared by the process according to the invention or not used in such a process for comparison purposes.
- Mixture F-E61.3V the components listed in Table 1 were combined in an electric mixer (Bosch Profi 67). For this purpose, first the aqueous PVAL mixture and the aqueous sulfuric acid mixture were combined by per se known mixing together to form a premix (or to a binder system) and this premix was then mixed with the preparation of quartz sand (molding material) by mixing in the electric mixer united. There was one to one Molded part moldable or stampable molding material mixture.
- the molding material mixture F-E61.3V is a molding material mixture prepared by the process according to the invention or used in such a process.
- Mixture F-E68.4 the ingredients listed in Table 1 were combined in an electric mixer (Bosch Profi 67). For this purpose, first the aqueous PVAL mixture and the aqueous sulfuric acid mixture were combined by per se known mixing together to a premix (or to a binder system) and this premix was then with the introduction of silica sand (molding material) by mixing in the electric mixer united. This gave rise to a moldable moldable or stampable molding material mixture.
- the molding material mixture F-E61.3V is a molding material mixture prepared by the process according to the invention or used in such a process.
- B-seal B-box The cold-mix molding compound (see Example 1) was rammed in a bending ram as described above. Subsequently, the molded molding mixture was prepared by the cold-box method by passing (under the process conditions) gaseous N, N-dimethylpropylamine (about 1 ml liquid, 15 s) according to the instructions in the VDG leaflet P73, No. 4.3, Method A. , hardened.
- the final strengths of the standard bending bars produced in Example 2 above were tested in each case: the final strengths of the standard B-cold box bending bars were tested for this purpose 24 hours after their production. The final strengths of the standard B-V38, B-E613V1 and B-68.4 bending bars were tested for this purpose 30 minutes after their preparation (drying). All standard bending bars were stored under laboratory conditions. In each case, a triple determination of the final strengths was carried out, as described in the VDG leaflet P73, No. 5.2, with a Georg Fischer strength tester type PFG with low-pressure gauge (with motor drive).
- nb values not determined. From the values given in Table 2 it can be seen that the molded parts produced by the process according to the invention (standard bending bars) B-E61.3V1 and B-E68.4 have at least comparable or even better values for the final strengths than one after one customary cold-box process produced corresponding molding.
- the molded part B-V38 (without catalytically active acid) produced by a non-inventive process showed comparatively the lowest flexural strength (final strength) under the experimental conditions.
- polyvinyl alcohol was polyvinyl alcohol (> 93%, granular) having a degree of hydrolysis of about 88 mol% and a dynamic viscosity in the range of 3.5 to 4.5 mPa s (measured as 4 wt .-% - aqueous solution at 20 ° C according to DIN 53015), methanol content: ⁇ 3 wt .-%; CAS RN 25213-24-5 used.
- Comparative Form Mixture F-V01 the ingredients listed in Table 3 were mixed together in an electric mixer (Bosch Profi 67) and stirred until foamy. The result was a deliquescent, pourable, but not moldable or malleable molding material mixture.
- Comparative molding material mixture F-V02 the ingredients listed in Table 3 were mixed together in an electric mixer (Bosch Profi 67) and stirred until foamy. This gave rise to a moldable moldable or stampable molding material mixture.
- Comparative Form Mixture F-V03 the ingredients listed in Table 3 were mixed together in an electric mixer (Bosch Profi 67) and stirred until foamy. The result was a deliquescent, pourable, but not moldable or malleable molding material mixture.
- the three comparative molding compounds F-V01, F-V02 and F-V03 were - as far as possible - in each case formed in a bending ram ram as described above (see Example 2) by ramming to a shaped molding material mixture.
- the molded molding material mixture was then cured to a cured molding:
- Comparative molding compound F-V01 Under the given standard conditions (ramming) no dimensionally stable formed molding material mixture could be produced, so that no cured molding could be produced.
- Comparative Form Mixture F-V02 a molded material mixture shaped into a bending seal was obtained. This was cured as indicated below (see Example 5) to a molded article (B-V02 seal) and the result was compared to the result of a process according to the invention (see below, B-E61.3V1). Comparative molding compound F-V03: no dimensionally stable shaped molding compound could be produced under the standard conditions (ramming) given. The molding material mixture was then heated in the bending mold for 1 min at 250 ° C in a drying oven and evaluated after cooling to room temperature: there had been no cured molding, the molding material mixture was still soft. Another, in the same way prepared molding material mixture was in the bending mold in the convection oven for 5 min heated at 250 ° C. As a result, a hard edge shell formed on the molded molding material mixture, but it still remained soft on the inside.
- Formed molding material mixtures F-V02 (comparison, see Example 4) and F-E61.3V1 (prepared according to the invention, see Example 2) were prepared and subjected to the conditions given below in Table 4 in the circulating-air drying oven for the cured molding (standard bending seal ) hardened. After each hardening, the flexural strengths were determined in each case on the mold parts which had been cooled and cured for 30 minutes under laboratory conditions (according to Example 3) and also indicated in Table 4.
- the cured moldings were then tested for water resistance according to the following method.
- the intact standard bending bars at 20 ° C and normal pressure for 30 minutes were independently immersed in deionized water so that they were just completely covered with water .
- the standard bending bars were immediately removed from the water and (as far as possible) checked for consistency. Subsequently, as far as possible, the residual hardness of the standard bending bars was tested using a core hardness tester GM-578 (Simpson Technologies GmbH, Switzerland).
- the respective standard bending seal was placed in each case on a solid base and the penetration depth of the core hardness tester (according to the handling instructions of the core hardness tester) each once at one point of the (in contact with the water) Measured outside surface.
- the measurement was carried out a total of three times at different points on the outside surface and the average of the three measurements is given in Table 4 ("Penetration outside surface").
- the indication "not measurable” in Table 4 means that no penetration depth with the core hardener could be measured at the corresponding bending bar, because it had been decomposed during storage for 30 min in the water. From the measured values or data given in Table 4, it can be seen that a cured molded article produced by a noninventive process does not resist waterfastness (after 20 minutes at 210 ° C.) or is not completely waterproof (after 30 minutes at 210 ° C.) ° C) was cured.
- a hardened molded article prepared by the process according to the invention had already hardened water-resistant after 20 minutes (standard bending strip does not disintegrate after removal from the water) and hardened continuously after 30 minutes (penetration depth of the core hardener on the inner cross-sectional surface ⁇ 4 mm ).
- Example 6 Determination of the Water Resistance of Standard Bending Rods
- Standard bender bars produced as in Example 2 above were placed on shelves so that only their ends rest (contact area about 1/10 of the total area of the underside of the standard bender bars, see below, table) 5).
- the shelves with the standard bows resting on them were placed in a container filled with water, so that the undersides of the standard bending bars were completely on the water surface and could absorb water through the capillary forces. Then, the water resistance of the standard bending bars was visually evaluated over a period of ten days.
- Standard bending bars B-cold box (comparison), B-V38 (comparison) and B-E61 .3V1 (prepared according to the process according to the invention) prepared in the preceding Example 2 were mixed with a conventional alcohol size (Koalid 4087 from Wilsontenes-Albertus GmbH) in a manner known to those skilled in the art (conditions: flow time 17.3 s, immersion time 7 s, drying 1 10 ° C. for 40 min, wall thickness 325 ⁇ m in the wet state).
- the standard bending bars sized with the alcohol sizing were then placed in a furan resin mold undiluted with a conventional zirconium-containing sizing (Zirkofluid 1219 from Wilsontenes-Albertus GmbH) (dimensions 280 ⁇ 200 ⁇ 130 mm) and in this form 1440 ° C, about 3.09 wt .-% carbon content, about 1.89 wt .-% silicon content, in each case based on the total mass of the cast iron), so that the standard Bending of the iron casting were each completely enclosed and experienced during casting in relation to the bearing load (by the iron as cast metal) a maximum load.
- a conventional zirconium-containing sizing Zirkofluid 1219 from Wilsontenes-Albertus GmbH
- the iron casting was sawed in the middle (along the bearing surfaces of the standard bending bars), so that the cavities produced by the standard bending bars (after their removal from the iron casting) in the iron casting are just in the middle of the length divided into two halves.
- the cross-sections of the cavities produced by the standard bending bars were thereby half each in the upper half of the sawed metal casting (produced by the iron casting overhead part of the standard bending bar, "upper mold half") and in the lower half of the sawn-on metal casting (produced by the part of the standard bending seal, "lower mold half") lying at the bottom of the iron casting.
- Standard bending seal B-cold box (comparison): The casting negatives of the upper (in the upper mold half) and underside (in the lower mold half) of the standard bending seal B-Cold-Box showed no significant deviation from the straight course of the wood scraper. Accordingly, the standard bending seal B-cold box barely deformed during casting with iron and exhibited a high cast resistance (see Fig. 6 and Fig. 7).
- Standard bending seal B-V38 (comparison): The casting negative of the upper side (in the upper mold half) of the standard bending seal B-V38 showed a clear concave deformation (away from the wooden spatula) in the middle (maximum height of deviation: approx mm). The casting negatively on the underside (in the lower half of the mold) of the standard B-V38 bending bender showed clear concave (away from the wooden blade) deformations (maximum height of the deviation: about 7 mm.) The standard bending seal B-V38 had thus significantly deformed during casting with iron and showed only a low cast strength (see Fig. 4 and Fig.
- Standard Biegeliegel B-E61 .3V1 manufactured according to the inventive method:
- the casting negatives of the upper (in the upper half of the mold) and underside (in the lower half of the mold) of the standard B-E61.3V1 bender showed no significant deviation from the straight course of the wooden scraper, so that the standard bender seal B-E61.3V1 barely deformed when cast with iron and showed a high cast resistance (see Fig. 8 and Fig. 9).
- the 24-h flexural strengths were then determined from the standard bending bows "B-cold box" obtained (comparison), analogously as indicated above in Example 3. From the obtained standard B-E68.4 bending bends, the flexural strength was determined after 30 minutes storage under laboratory conditions (room temperature and room humidity), after completion of the drying process (final strengths). The results of all the above measurements are given below in Table 6 (averages of 3 measurements). Also indicated in Table 6 are the respectively determined values of the gas permeabilities of the standard bending bars and standard testing cylinders as well as their weight. The gas permeability is a test value that provides information about the structure compaction. In the case of the feeder in particular, this is a characteristic value which can provide information about the sufficient removal of casting gases during the casting. Table 6: Ingredients of molding material mixtures for insulating feeders
- Insulating feeders were shot in the same mold on the core shooter from the insulating feed masses prepared above in Example 8 with molding material mixture "F-E68.4 (2)". The curing took place for 25 min at 210 ° C in a drying oven (circulating air). Insulating feeders made in this manner were placed in a cold box bonded molding sand mold and cast with aluminum to test for their behavior under metal casting conditions. Other insulating feeders prepared in this way were also set in loose foundry sand and poured off with iron instead of aluminum.
- the insulating feeder produced according to the invention showed a clearly better unpacking behavior than the insulating feeder produced with the comparison molding compound F-cold box (2): when the cast sample was mechanically pulled, the feeder poured with iron almost completely disintegrated.
- the resulting iron casting also showed a clearly rere surface, with a light mechanically removable sand and a smoother surface texture than the iron casting produced with the insulating feeder made with the comparative molding compound F-Cold Box (2).
- test specimens (standard Biegeler bar and standard test cylinder) were molded from the resulting molding material mixtures and cured analogously as above in Example 2 to form hardened standard bending bars and standard test cylinders as (representative or model) cured moldings.
- the curing of the test specimens with the molding material mixture F-E68.4 (3) was carried out by heating and removing water for 25 min at 210 ° C in a drying oven (circulating air).
- the bending strengths were then determined from the standard bending bars obtained, analogously as indicated above in Example 3. The results of these measurements are given below in Table 7 (averages from 3 measurements).
- Table 7 Also indicated in Table 7 are the respectively determined values of the gas permeabilities of the standard test cylinders and their weight. Table 7: Components of molding material mixtures for exothermic feeders
- Example 1 Burn-off of exothermic feeders
- aqueous PVAL mixture and “aqueous sulfuric acid mixture” given in Table 9 correspond to the constituents indicated in Example 1.
- the aqueous binder systems WB-E61.3V1 and WB-E68.4 are aqueous binder systems to be used according to the invention.
- the aqueous binder system WB-V38 is an aqueous binder system which can not be used according to the invention for comparison.
- Example 13 Sample casting of iron cubes
- the molding compound mixtures given in Table 10 below were each shaped into feeders in a core shooter.
- Table 10 Compositions of molding material mixtures for feeders
- the constituents indicated in Table 10 correspond in each case to the constituents stated in Example 1 or their meanings.
- sodium waterglass binder 48/50 was an aqueous solution of a standard water glass binder having a water glass content (sodium silicate content) in the range of 25 wt .-% to 35 wt .-% and a pH at 20 ° C in the range of 1 1 to 12 (CAS RN 1344-09-8).
- the aforementioned feeders were each tested by their use in the trial cast of an iron cube (model for a metallic casting) on their applicability, in particular the quality of their Feiser für.
- the feeders of the same size were used in the sample casting of cubes of the module (ie with a volume to surface ratio of 1.68 cm with iron (GGG40) at a casting temperature of 1400 ° C.
- the expert in the field of foundry technology often uses cubes, which have a significantly higher modulus than the feeders, in order to be able to extract the best possible information for solidification from the experiment.
- the quality of the feeding effect is determined by the depth of the voids entering the cube, with voids reaching deeper into the cube (the metal casting) implying a poorer feeding effect.
- test cubes prepared as indicated above were sawed in the middle after casting and cooling to room temperature in the middle (halved) to reveal their cross-section and to assess the quality of the casting, and the quality of the feeder action of the feeder used in each case.
- the cross-sections of the sample cube obtained by sawing with the iron remainder attached to the top are shown in FIG. 10 (iron casting using the feeder "feeder-coldbox" not manufactured according to the invention), in FIG. 11 (iron casting using the noninventive invention and in FIG. 12 (iron casting using the feeder "Speiser-B-E68.4" produced according to the invention).
- Fig. 10 it can be seen that when using a cold-box bound feeder under the experimental conditions a significant voids occurs, which extends into the metallic casting.
- the inscription "-15 mm" (left half of the cross section) or "- 16 mm” (right cross section half) indicates the distance between the line recognizable in the picture above (on the remainder of the line approach, ie the boundary between metallic residual feeder and the metallic casting ) and the line visible in the picture below (mark for the lowest point of the voids in the metallic casting).
- Fig. 1 1 it can be seen that when using a water glass-bound feeder not produced according to the invention under the experimental conditions a pronounced voids formation takes place, which extends far into the metallic casting.
- FIG. 12 it can be seen that when using the feeder "Speiser-B-E68.4" produced in accordance with the invention, the resulting voids reach far less deeply into the iron casting (sample cube) than when using known water-glass bonded or cold Box-bound feeder.
- the inscription "-3" (mm) (left half of the cross section) or "- 1" (mm) (right cross section half) indicates the distance between the line recognizable in the picture above (on the residual feeder approach, ie the boundary between metallic remainder feeder) and the metallic casting) and the line visible in the picture below.
- a feeder produced according to the invention has a significantly improved feeding capacity than the known cold-box or waterglass-bound feeder used for comparison.
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Mold Materials And Core Materials (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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DE102017131255.2A DE102017131255A1 (de) | 2017-12-22 | 2017-12-22 | Verfahren zur Herstellung eines metallischen Gussstücks oder eines ausgehärteten Formteils unter Verwendung aliphatischer Polymere umfassend Hydroxygruppen |
PCT/EP2018/085425 WO2019121637A1 (de) | 2017-12-22 | 2018-12-18 | Verfahren zur herstellung eines metallischen gussstücks oder eines ausgehärteten formteils unter verwendung aliphatischer polymere umfassend hydroxygruppen |
Publications (1)
Publication Number | Publication Date |
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EP3727722A1 true EP3727722A1 (de) | 2020-10-28 |
Family
ID=64899313
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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EP18826293.5A Withdrawn EP3727722A1 (de) | 2017-12-22 | 2018-12-18 | Verfahren zur herstellung eines metallischen gussstücks oder eines ausgehärteten formteils unter verwendung aliphatischer polymere umfassend hydroxygruppen |
Country Status (7)
Country | Link |
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US (1) | US11253913B2 (de) |
EP (1) | EP3727722A1 (de) |
CN (1) | CN111511482B (de) |
DE (1) | DE102017131255A1 (de) |
MX (1) | MX2020006543A (de) |
TW (1) | TW201930235A (de) |
WO (1) | WO2019121637A1 (de) |
Families Citing this family (1)
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CN115947606B (zh) * | 2022-12-16 | 2024-03-12 | 中航装甲科技有限公司 | 一种硅基陶瓷型芯水溶性强化剂及强化方法 |
Family Cites Families (19)
Publication number | Priority date | Publication date | Assignee | Title |
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US3926716A (en) | 1974-03-19 | 1975-12-16 | Procter & Gamble | Transfer and adherence of relatively dry paper web to a rotating cylindrical surface |
US3960798A (en) * | 1974-08-26 | 1976-06-01 | Hitachi, Ltd. | Process for regulating hardening speed of self-hardening mold |
JPS51119321A (en) | 1975-04-11 | 1976-10-19 | Hayashibara Biochem Lab | Sand mold composite material for casting metal |
US4487868A (en) | 1983-05-25 | 1984-12-11 | Acme Resin Corporation | Foundry core compositions |
DE3928858A1 (de) | 1989-08-31 | 1991-03-07 | Beiersdorf Ag | Vernetzte hydrogele und verfahren zu deren herstellung |
US5320157A (en) * | 1993-01-28 | 1994-06-14 | General Motors Corporation | Expendable core for casting processes |
JP2951233B2 (ja) | 1995-05-16 | 1999-09-20 | 不二製油株式会社 | 無機質成形体の製造方法 |
US5810918A (en) * | 1996-06-21 | 1998-09-22 | Amcol International Corporation | Method of analyzing and/or treating foundry sands for reduced VOCs |
BRPI0414035B1 (pt) * | 2003-09-02 | 2016-11-22 | Sintokogio Ltd | método para formar moldes com mistura de material agregado espumado, mistura de material agregado espumado para formar moldes e macho para fundir metal |
ATE509714T1 (de) | 2004-02-25 | 2011-06-15 | Sintokogio Ltd | Verfahren zur herstellung eines gussteils |
EP1769860B1 (de) | 2004-07-02 | 2011-12-21 | Sintokogio, Ltd. | Formverfahren und durch das verfahren hergestellte formen |
DE102007012489A1 (de) | 2007-03-15 | 2008-09-25 | AS Lüngen GmbH | Zusammensetzung zur Herstellung von Speisern |
DE102007012660B4 (de) | 2007-03-16 | 2009-09-24 | Chemex Gmbh | Kern-Hülle-Partikel zur Verwendung als Füllstoff für Speisermassen |
DE102007026166A1 (de) | 2007-06-04 | 2008-12-11 | Kuraray Europe Gmbh | Verfahren zur thermoplastischen Formgebung von Polyvinylalkohol und hiermit hergestellte Formkörper oder Granulate |
DE102011079692A1 (de) | 2011-07-22 | 2013-01-24 | Chemex Gmbh | Speiser und formbare Zusammensetzungen zu deren Herstellung |
DE102012104934A1 (de) * | 2012-06-06 | 2013-12-12 | Ask Chemicals Gmbh | Forstoffmischungen enthaltend Bariumsulfat |
DE102015223008A1 (de) | 2015-11-21 | 2017-05-24 | H2K Minerals Gmbh | Form, Verfahren zu ihrer Herstellung und Verwendung |
DE102015120866A1 (de) | 2015-12-01 | 2017-06-01 | HÜTTENES-ALBERTUS Chemische Werke Gesellschaft mit beschränkter Haftung | Verfahren zur Herstellung von feuerfesten Kompositpartikeln und von Speiserelementen für die Gießereiindustrie, entsprechende Speiserelemente und Verwendungen |
DE102016205960A1 (de) | 2016-04-08 | 2017-10-12 | HÜTTENES-ALBERTUS Chemische Werke Gesellschaft mit beschränkter Haftung | Verwendung von geschlossen-porigen Mikro-Kugeln aus expandiertem Perlit als Füllstoff für die Herstellung von Formkörpern für die Gießereiindustrie |
-
2017
- 2017-12-22 DE DE102017131255.2A patent/DE102017131255A1/de not_active Withdrawn
-
2018
- 2018-12-18 CN CN201880083149.7A patent/CN111511482B/zh not_active Expired - Fee Related
- 2018-12-18 US US16/956,727 patent/US11253913B2/en active Active
- 2018-12-18 EP EP18826293.5A patent/EP3727722A1/de not_active Withdrawn
- 2018-12-18 MX MX2020006543A patent/MX2020006543A/es unknown
- 2018-12-18 WO PCT/EP2018/085425 patent/WO2019121637A1/de unknown
- 2018-12-22 TW TW107146677A patent/TW201930235A/zh unknown
Also Published As
Publication number | Publication date |
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CN111511482B (zh) | 2022-07-08 |
TW201930235A (zh) | 2019-08-01 |
US11253913B2 (en) | 2022-02-22 |
CN111511482A (zh) | 2020-08-07 |
DE102017131255A1 (de) | 2019-06-27 |
MX2020006543A (es) | 2020-12-09 |
WO2019121637A1 (de) | 2019-06-27 |
US20210121942A1 (en) | 2021-04-29 |
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