DK170553B1 - Process for making casting cores and molds and using them for making light metal work - Google Patents

Description

DK 170553 B1

The invention relates to a process for making molds and casting cores and their use in casting light metal castings.

Many different types of bonding or binder materials have been used in the manufacture of mold cores and molds. The binder material, after curing, should provide various desirable properties to the core and molds. Examples of such properties are wear resistance, moisture resistance and crumb resistance or shake resistance. In the production of cores or molds, high production is also a desired goal.

10 The modern core-making and mold-making technique began with the use of unsaturated drying oils derived from natural products as a binder. Linseed oil is the first example of a drying oil.

Upon exposure to air, linseed oil and other unsaturated oils undergo oxidatively initiated polymerizations resulting in the formation of 15 solid, highly crosslinked structures. The polymerization can be accelerated by heat or chemical methods. These binding materials are known in the industry as nuclear oils. When forming a core, the oil is mixed with sand and the sand mixture is brought into the form of a core or mold. The curing is carried out by heating or maturing the core or mold for a long period of time. Core oil binders may contain, in addition to the oil component, other ingredients such as oil-derived esters, unsaturated hydrocarbon resins and solvents. Nuclear oil-based processes for making casting bodies such as molds or cores have been known for 50-60 years.

25 Processes faster than the above-mentioned nuclear oil processes were introduced 25 - 30 years ago. These processes require heat curing for the binder material. These so-called "hot-box" core methods are based on a thermosetting resin composition.

Chemically, these thermosetting resins include phenolic resins, urea formaldehyde resins and furfuryl alcohol formaldehyde resins. In addition to the use of heat to cure or polymerize these binder materials, acids are often incorporated as catalysts.

For approx. Ten years ago, high-temperature room temperature processes were introduced to produce cast cores and molds. The binder formed by these processes is based on urethane chemistry. Actually, the binder material consists of two liquid resin components. One component is a phenolic resin. The second component is a polymeric isocyanate. The phenolic resin and isocyanate resin are mixed with sand and can be used in either a "cold box" or a "no bake" system.

40 In the "cold box" system, the sand coated with the two components is blown into a core box. When the sand is blown into core book 2, a gaseous tertiary amine is passed through the core box to effect immediate cure or solidification to form the binder. This technology is disclosed in U.S. Patent 3,409,579. In the "no bake" core preparation process, the polyisocyanate component, the phenolic resin component and the catalyst are all mixed with sand at the same time. .

The sand mixture is then poured into a core box or into a pattern. The sand mixture remains liquid for a certain period of time. When this time has elapsed, the catalyst initiates the cure or polymerization, and the core is formed rapidly as the binder components 10 react rapidly to form a urethane binder. U.S. Patent No. 3,676,392 discloses "no bake" binders.

A further binder composition and procedure for forming a molding binder is disclosed in U.S. Patent No. 3,879,339. This patent describes a method by which a "cold box" is used, i.e. room temperature, and gas cure to form a molding binder comprising an organic resin which can be cured with an acid and an oxidizing agent. This binder component is cured with sulfur dioxide gas. The combination of sulfur dioxide plus the oxidant leads to the formation of sulfuric acid, which acid serves to cure the 20 acid curable organic resin. Actually, the sulfuric acid is formed in situ and the acid reacts with the resin. Thus, curing of the binder composition is provided.

None of the molding binders described above are of such utility and versatility that they can be considered as a universal or irreplaceable molding adhesive. Each of them has its advantages and disadvantages to some extent.

It is therefore an object of the present invention to provide a process for making moldings based on a binder with a chemistry that has not heretofore been used in the molding field or for other areas of binder application. It is a particular object of the present invention to provide a "cold box" type binder which exhibits rapid cure. Another objective is to provide a "cold box" binder useful for casting aluminum and other light metals.

The invention relates to a method of the kind set forth in the preamble of claim 1 and is peculiar to the characterizing part of claim 1. Molds and cores made using these binders exhibit superior crumb performance when used in casting light metals, ie. metals cast at low casting temperatures. The hardening of the binder material to form the binder sub-composition preferably takes place at room temperature and occurs almost immediately.

From DE-OS 24 17 939 it is known to make mold cores and molds by adding the sand an acrylic acid ester, an organic peroxide and a polymerization accelerator. The use of gaseous SO2 as a catalyst is not mentioned in this specification.

Thus, in the present invention, a cast binder is used for which the chemistry is different from that used to form any binder heretofore known to be useful in the casting industry. The binder can also be used as a binder or binder in areas other than the molding industry. The chemistry on which the binder is based is analogous to a chemistry that has been used so far for coatings, cf. for example. British Patent Specification No. 1,055,242, and binders, cf. for example.

15 different patents in the name of Loctite Corporation. An anaerobic cured casting binder based on a similar chemistry is disclosed in Canadian Patent No. 1,053,440. This binder cures very slowly and heating is required to effect curing. The present invention does not include any anaerobic curing process, but instead relates to rapid, almost instantaneous curing at room temperature.

It is well known that casting bodies, i.e. cores and molds are formed by applying a binding substance or chemical to sand or other aggregate material, imparting the desired shape to the sand and allowing or causing the binding substance or chemical to harden to form a binder. The present invention can be considered as a binder obtained by bringing two parts together. Part I is a binding substance or bond that undergoes polymerization and cross-linking to adhere to, retain or bond the sand or other aggregate in the desired form. The second part (Part II) is an agent which causes polymerization and crosslinking of Part I. This agent is herein referred to as "free radical initiator". The term "crosslinking" here refers to a chain structure which results when a polymer is involved either by bonding to another polymer or to a monomer. The term "polymerization" includes "crosslinking" but also refers to the chain polymerization which occurs only for monomers.

Part I of the binder system can be described as an unsaturated composition which can be crosslinked or polymerized by free radical mechanism. The unsaturation is preferably terminated or in associated groups.

Even internal unsaturation is acceptable and polymerization will result in 40 after combination with Part II. It is also possible, depending on the synthesis method of component Part I, to have a component part I, which has both a terminal and / or associated unsaturation and also an internal unsaturation in the same component. It is believed that the polymerization mechanism is practically completely free-radical type when cross-linking compositions (i.e., unsaturated polymer or unsaturated polymers) are involved. When certain monomers are used as a binding composition, * it is possible that part of the polymerization may take place by a mechanism different from a free radical. It is therefore to be understood that the present application is not limited to any particular polymerization mechanism, but that the term "free radical mechanism" is used for the sake of simplicity and correctly describes such a mechanism in practically all cases. However, it is to be understood that in addition to the free radical mechanism, other mechanisms may also be involved in the polymerization under certain circumstances. The cure is provided using Part II, a free radical initiator containing a peroxide and a catalytic agent. It has been found that unsaturated reactive monomers, polymers, and mixtures thereof (i.e., the binding composition) can be used as a binding material that cures instantaneously by selecting certain catalysts in the free radical initiator. The unsaturation found in the monomers and polymers is as indicated by 20 ethylenic character. For example. reactive polymers, which may also be described as oligomers or adducts, which preferably contain vinyl or acrylic unsaturation, are used as binder compositions which, after polymerization, provide a binder for sand grains and molds. The free radical initiator (Part II) is mixed with the reactive polymer 25 or monomer (Part I) to form free radicals that polymerize the binding composition to form the binder. This combination of a peroxide and the catalytic agent is herein referred to as "free radical initiator".

The free radical initiator can be used to effect polymerization of 30 Part I materials in a variety of ways. The peroxide may e.g. are mixed with the Part I material and this mixture is distributed homogeneously on sand. After the sand is shaped as desired, the shaped sand can be exposed to the catalytic agent. Alternatively, the catalytic agent may be added to the Part I material, and this mixture is used to coat the sand and the coated sand is then formed as desired. The peroxide component of the free radical initiator can then be added to the molded article and cure occurs by polymerization. It is also possible to divide the Part I material into two portions. The catalytic agent may be added to one portion and the peroxide may be added to the other portion. When the two portions are combined after application of at least one portion with the material to be bonded, polymerization occurs. Depending on the type of catalytic agent or equipment used and the application used, this latter process may not be practicable. However, if the binding material is used to bond non-particulate materials, this latter method may be particularly useful.

As described above, the binding material is a polymerizable, unsaturated monomer, polymer or a mixture of such monomer (s) and polymer (s). Examples of materials that are suitable monomeric compounds for the component I component include a wide variety of monofunctional, difunctional, trifunctional and tetrafunctional acrylics. A representative list of these monomers includes alkyl acrylates, hydroxyalkyl acrylates, alkoxyalkyl acrylates, cyanoalkyl acrylates, alkyl methacrylates, hydroxyalkyl methacrylates, alkoxyalkylmethacrylates, cyanoalkylmethacrylates, N-alkoxymethylacrylamides and N-alkoxymethyl Difunctional monomeric acrylates include hexanediol diacrylate and tetraethylene glycol diacrylate. Other acrylates which may be used include e.g. trimethylolpropane triacrylate, methacrylic acid and 2-ethylhexylmethacrylate. It is preferred to use polyfunctional acrylates when the monomer is the only binding unit in the binder system. As stated above, crosslinking may not occur when only monomers are used as the binding material. Furthermore, mechanisms other than the free radical mechanism may cause polymerization.

Examples of unsaturated reactive polymers which have been found to be particularly useful in forming this binder are epoxy acrylate reaction products, polyester / urethane / acrylate reaction products, polyether acrylates and polyester acrylates. Unsaturated polymers which can be used as a Part I composition include commercially available materials such as "UVITHANE" 782 and 783, acrylic urethanol oligomers from Thiokol and CMD 1700, an acrylic ester of an acrylic polymer, and "CELRAD" 3701, an acrylic epoxy resin Reactive polymers can be prepared in a number of ways. A preferred method of preparing the reactive polymers is to form an isocyanate-distilled prepolymer by reacting a polyhydroxy compound or polyol with a diisocyanate. further with a hydroxyalkyl acrylate to form an oligomer.

Another method which has been found to be advantageous is to react a polyisocyanate compound, preferably a diisocyanate compound, with a hydroxyalkyl acrylate. The reaction product is an "adduct" of these two materials. Addition oligomers and adducts can be prepared simultaneously under appropriate conditions.

In addition to the reactive unsaturated polymer, a solvent, preferably one of a reactive nature, may be included and preferably included as a component of the binding material. Depending on the nature of the unsaturated binding material, inert solvents may also be used. The preferred solvent is an unsaturated monomeric compound such as that described above in the description of monomeric Part I materials. Accordingly, the Part I material may comprise a mixture of these unsaturated monomers and unsaturated polymer suggested above for use as Part I material per se. The best results occur when a solution of an unsaturated reactive polymer and a monomeric unsaturated solvent is used. This combination seemed easier to undergo copolymerization and cross-linking to form a bonding matrix necessary to either adhere the sand or other aggregate together to form the cast core or mold or to bond other materials.

As indicated, in Part I of the binder system, it is preferred to use an unsaturated monomeric compound as a solvent with the unsaturated polymer. As described above, these monomers containing unsaturation can be crosslinked with the polymer in addition to serving as a solvent for the unsaturated polymer. Any of the unsaturated monomers (or combinations thereof) described as being useful Part I materials per se are also useful as solvents. Ethylenic unsaturation, preferably of the vinyl or acrylic type, is recommended. Examples of preferred monomers for use as solvents for the unsaturated polymers include pentaerythritol tri triacrylate, trimethylol propane triacrylate, 1,6-hexanediol diacrylate and tetraethylene glycol diacrylate used as a solvent for the unsaturated polymer. The amount of monomer in Part I can be from 0 up to 25%, based on the total weight of the binding composition of Part I.

It is also possible to use the reactive polymer as Part I material and the free radical initiator without the presence of any solvent for the unsaturated monomer, including unsaturated polymer. It is also possible to use the unsaturated monomer as the Part I material with a free radical initiator, but without the reactive polymer, for the purpose of obtaining a polymerized binder. Neither of the two combinations described above is preferred. As described above, the preferred binder system Part I containing a reactive unsaturated polymer is dissolved in a reactive diluent, preferably a monomeric unsaturated solvent, and Part II contains a free radical initiator.

The free radical initiator is made up of two components. The first component is an organic peroxide. The peroxide level may vary widely, to some extent depending on the catalytic * used.

agent. However, it can generally be said that from 0.5 to 2% peroxide, 40 based on the weight of the binding material (Part I), will provide satisfactory bonding under most conditions. Examples of suitable peroxides include tert.butyl hydroperoxide, cumene hydroperoxide and methylethyl ketone peroxide. It is worth noting that the hydroperoxides are far preferred over the peroxides. Unsatisfactory curing has been observed using peroxide. Mixtures of peroxides and hydroperoxides as well as mixtures of hydroperoxides are useful.

In preferred casting practice, the unsaturated reactive polymer, monomer or mixtures thereof and the peroxide component of the free radical initiator are mixed with sand in a conventional manner. The sand mixture is then formed into a desired mold configuration by stamping, blowing or other known mold core and mold making methods. The 10-shaped blank is then exposed to the catalytic component of the free radical initiator, i.e. gaseous SO2. This gas is only present in catalytic amounts as indicated above. The exposure time of the contact between the sand mixture and the gas can be as little as 1/2 second or less and the binder component cures upon contact with the catalytic agent. Using SO 2 as the catalytic agent in a "cold box" casting process, it is suspended in a stream of carrier gas in known manner. The carrier gas is usually N2. As little as 0.5% SO 2, based on the weight of the carrier gas, is sufficient to effect polymerization. It is also possible to expose the binder component 20 to SO2 without the presence of any carrier gas.

Part I may also contain any constituents. For example. additives for wetting and foaming can be useful. Silanes have been found to be particularly useful additives. Particularly preferred are unsaturated silanes, e.g., vinyl silanes.

The advantages of the binding composition as a molding binder are as follows. The crumbling ability of the binder used for casting aluminum is excellent. It has been found that this binder easily crumbles, ie. shaken out of cast aluminum blanks by applying minimal external energy. The binder also provides good strength properties.

30 "Bench life" time for sand mixed with Part I is long. The surface finish obtained from molded articles made using this binder and method has proven to be very good. The production rate of cores and molds made using this binder system is extremely fast.

In a foundry where the binder composition described herein is used, Part I and a component of the free radical initiator, preferably the peroxide, are mixed with sand or other suitable molding assembly in a known manner. The sand mixture is then formed into the desired molding, cores or molds, in known manner. The sand mixture is then exposed to the second component of the free radical initiator, preferably the catalytic agent, which is sulfur dioxide gas, and polymerization of the binder material Part I occurs immediately to form the binder herein.

The present invention is illustrated in more detail by the following Examples, in which all partial indications are by weight and all percentages.

5 entries are weight percentages unless otherwise stated.

Example 1. '

Gel tests are performed with various unsaturated monomers and polymers to determine their tendency to polymerize and the rate of polymerization. When conducting the experiments, mix from ca. 1.5 to 2 g of unsaturated monomer or polymer (i.e., Part I) with 0.03 g of tert-butyl hydroperoxide (the peroxide component of the free radical initiator). This mixture is then exposed to sulfur dioxide gas (the catalytic agent in the free radical initiator) either by dispersing the gas in the liquid (bubbling) or by creating a SO 2 atmosphere over the liquid (contact). The results listed below indicate that all unsaturated monomers and polymers polymerize. Thus, all of the compounds listed below are potential binders. The disclosed compounds which show rapid polymerization or gelation have the greatest potential value as a molding agent to make the mold and core preparation quick in high speed manufacture using a so-called "cold box".

Part I Polymerization course

Acrylic Acid Fast, on contact with SO2

Ethyl Acrylate Slow, on Contact with SO2 25 n-Butyl Acrylate Slow, on Contact with SO2

Isobutyl Acrylate Slow, on contact with SO2 2-Ethylhexyl acrylate Fast, on contact with SO2

Isodecyl Acrylate Fast, on contact with SO2 2-Ethoxyethyl acrylate Fast, on contact with SO2 30 Ethoxyethoxyethyl acrylate Fast, on contact with SO2

Butoxyethyl acrylate Fast, in contact with SO2 *

Hydroxyethyl acrylate Fast, on contact with SO2

Hydroxypropyl acrylate Fast, on contact with SO2 *

Glycidyl acrylate Fast, on contact with SO2 35 Dimethylaminoethyl acrylate Quick, on contact with SO2

Cyanoethyl acrylate Fast, in contact with SO2 I.'1 '/ · ;: r 9 DK 170553 B1

Diacetone acrylamide in methanol, 50% Fast, on contact with SO2

Acrylamide in methanol, 50% Fast, on contact with SO2 (N-Methylcarbamoyloxy) - 5 ethyl acrylate Quick, on contact with SO2

Methylcellosolveacrylate Fast, on contact with SO2

Phenoxyethyl acrylate Fast, on contact with SO2

Benzyl acrylate Fast, on contact with SO2

Ethylene glycol acrylate Phthalate Fast, on contact with SO2

Melamine Acrylate Fast, on contact with SO2

Diethylene glycol diacrylate Fast, on contact with SO2

Hexanediol diacrylate Fast, on contact with SO2

Butanediol diacrylate Fast, in contact with SO2 15 Triethylene glycol diacrylate Quick, in contact with SO2

Tetraethylene glycol diacrylate Fast, on contact with SO2

Neopentyl glycol diacrylate Quick, on contact with SO2 1,3-Butylene glycol diacrylate Quick, on contact with SO2

Trimethyloipropanetriacrylate Fast, on contact with SO2 20 Pentaerythritol triacrylate Fast, on contact with SO2

Methacrylic acid Fast, on contact with SO2

Methylmethacrylate Slow, by bubbling with SO2 2-Ethylhexylmethacrylate Slow, by bubbling with SO2

Hydroxypropylmethacrylate Fast, on contact with SO2 25 Glycidylmethacrylate Fast, on contact with SO2

Dimethylaminoethyl methacrylate Fast, on contact with SO2

Ethylene glycol dimethacrylate Fast, on contact with SO2

Trimethylol propane trimethacrylate Fast, on contact with SO2

Acrylated urethane derived from 30 glycerol 65% in MIAK / HiSOL-10 Quick, on contact with SO2 N-Methylolacrylamide in water 60% Quick, on contact with SO2 N- (Isobutoxymethyl) acrylamide in methanol 50% Quick, on contact with SO2

Epocrylic R-12 resin (Shell) 35 acrylic epoxy 80% in acetone Slow, on contact with SO2 10 DK 170553 B1 "UVITHANE" 783 (thiocol / chem. Div.) Acrylated urethane oligomer Fast, on contact with SO2 "AROPOL" 7200 (ASHLAND) Saturated Polyester Resin in Acetone 60% Slow, Upon Contact with SO2 5 "RICON" 157 (Colorado Specialty ,,

Chemical) an unsaturated hydrocarbon resin in acetone 50% Slow, on contact with SO2

Hydroxy PB G-2000 (Hystl Co.) c an unsaturated hydrocarbon resin 10 in acetone 50% Slow, on contact with SO2

Example 2.

An unsaturated polymer is prepared by reacting the equivalent of 1 mole of pentanediol and the equivalent of 4 moles of hydroxyethyl acrylate with the equivalent of 3.0 moles of toluene diisocyanate. Dibutyltin dilaurate is used to catalyze the reaction. Based on the solids content, 0.14% catalyst is used. Hydroquinone monoethyl ether is used as an inhibitor. The reaction is carried out in a reaction agent (solvent) consisting of ethyl hexyl acrylate and hydroxyethyl acrylate. In carrying out the reaction, a mixture of TDI and solvent is added to the reaction vessel. Pentanediol is added to this mixture followed by the addition of hydroxyethyl acrylate. When the addition of hydroxyethyl acrylate is complete, the catalyst is added. The reaction is carried out under air supply. The reaction proceeds at 40 - 45 ° C for 2.1 hours, then raises the temperature to 80-85 ° C and the reaction is continued for 25 hours in 4.3 hours, then 0.03% inhibitor is added and the reaction is continued for 1/2 hour. The product is allowed to cool. The product is tested for non-volatile components and 59.2% is found. This corresponds to a theoretical amount of non-volatile constituents of 60%. The viscosity of the product is 6.0 St. 20 g of unsaturated polymer is then mixed with 1.6 g of acrylic acid, 10.7 g of diethylene glycol diacrylate, 9.9 g of trimethylolpropane trimethacrylate and 2.0 g of vinylsilane. Acrylic acid, diethylene glycol diacrylate and trimethylol propane triacrylate are unsaturated monomers. This solution of unsaturated polymer and unsaturated monomers is referred to as Part I. 1 g of tert.butyl hydroperoxide, the peroxide component of the free radical initiator, is added to the solution of the unsaturated polymer and the unsaturated monomers.

Wedron 5010 sand (washed and dried fine-grained silica sand, »AFSGFN 66) is placed in a suitable mixer. Part I and the peroxide component of the free radical initiator are mixed with the sand until a uniform distribution is obtained. The level of Part I plus peroxide is 2%, calculated on the ^ 40 sand weight.

The sand mixture is blown into a conventional core cavity or box to produce standard tensile strength tests known as "meat bone". The meat bone test nuclei are cured by exposing the nuclei to the catalytic component of the free radical initiator. The catalytic component is gaseous sulfur dioxide. The nuclei are exposed to the SO2 catalyst for approx. 1/2 second (gassing time) and the catalyst is removed by blowing with nitrogen for 15 seconds and the core removed from the box. The tensile strengths of the cores are in MPa 1.54 outside the box and 1.41 after 3 hours and 1.57 after 24 hours.

Meatbone cores, similar to those described above, are used for shredding experiments with cast aluminum blanks. Seven tensile strength tests (meat bone) 10 are placed in a mold. The mold is connected to an inlet system. The mold is made so that hollow molded blanks with a metal thickness of approx. 5.4 mm on all sides. An open end of the molded blank is intended to remove the core from the mold. Melted aluminum at approx.

700 ° C made from aluminum blanks is poured into the mold. After 15 cooling for approx. For 1 hour, the cast aluminum blanks are removed from the inlet system and taken out of the mold for shaking experiments.

Shaking tests are performed by placing a molded blank in a container with a volume of approx. 3.8 liters (1 gallon). The container is placed on a shaking mechanism and shaken for 5 minutes. The weight of the sand core, which is removed from the molded article in this way, is compared to the initial weight of the sand core and a percentage shaking is calculated. Sand that remains in the cast after the shaking described above is removed by scraping and also weighed. The sand core bonded with the binder described above is found to have a shaking of 100%. It should be noted that the shaking test described above is not a standard test. So far, no standard test is known to measure this quality. It is believed that the test used provides a reliable view of the crumb performance of a binder and can be used to compare the relative crumb performance of the binder.

30 The percentages stated are subject to some uncertainty but are reliable indicators.

12 DK 170553 B1

Example 3

Sand Wedron 5010 at 23-26 ° C Part I

a) unsaturated monomeric acrylic acid 1.6 g, diethylene glycol diacrylate 10.7 g, trimethylol propane trimethacrylate 9.9 gb) unsaturated polymer synthesized as described below, * 20 g unsaturated polymer synthesis 10 i) polyisocyanate in molar equivalents TDI 4 ii) polyol, in molar equivalents glycerol - 1 iii) acrylate, in molar equivalents hydroxyethyl acrylate, 5 iv) catalyst dibutyltin dilaurate 0.14% C / hr 40 ° -45 ° for 2.13 hours then 80 ° -85 ° for 4.8 hours ix) viscosity, St 16.0 x)% non-volatile material, actually 63.9 25 theoretical 60.0 c additive in vinyl silane - 2.0

Free radical initiator (Part II) a) peroxide component 2.2% tert.butyl hydroperoxide b) catalytic component SO2 gas

Penetration time, s 15 with N2

Tensile strength in MPa when removing box 1.23 3 hours 1.50 35 24 hours 1.61 *

Binder level (part I + peroxide component) 2% cast metal aluminum shaking,% 100 DK 170553 B1 13

Example 4 5

Sand Wedron 5010 Wedron 5010

Part I

a) unsaturated monomeric acrylic acid 1.6 g, hydroxyethyl acrylate diethylene glycol di 2.2 g, dicyclopentene acrylate 10.7 g, nyl acrylate 20.8 g, trimethylolpropane (N-methylcarbamoyl triacrylate 9.9 g loxy) ethyl acrylate 17, 3 g 10 b) unsaturated polymer synthesized as described below, 20 g unsaturated polymer synthesis 15 i) polyisocyanate, in molar equivalents TDI, 3 ii) polyol, in molar equivalents Olin 20-265a \ 1 a) polyoxypropylene glycol 20 iii) acrylate, i molar equivalents of hydroxyethyl acrylate, 4 iv) catalyst dibutyltin dilaurate, 0.14% v) hydroquinone monomethyl ether inhibitor vii) solvent ethylhexyl acrylate and hydroxyethyl 25% acrylate, 40% viii) temperature / time 40 ° - 45 ° for 2.1 and ° C / hour 80 ° - 85 ° in 4.75 ix) Viscosity 4.2 x)% non volatile material, in fact 59.2 theoretical 60.0 c) Additive vinylsilane 2.0 g

Free radical initiator (Part II) a) peroxide component 11.3% cumene hydro- 2.4% tert.butyl hydroperoxide peroxide b) catalytic component SO2 gas SO2 gas

Gassing time, s 0.5 1

Penetration time s 15 with n2 15 with N2

Tensile strength in MPa 40 when removing box 1.10 3 hours 0.17 24 hours 48 hours 1.60 14 DK 170553 B1

Binder level (part I + peroxide component) 2% 2% cast metal aluminum shaking% 100 5 Example 67 *

Sand Wedron 5010 Wedron 5010

Part I ta saturated monomeric pentaerythritol acrylic acid 7.2 g, triacrylate 40 g ethylene glycol diacrylate 21.4 g, trimethylol propane triacrylate 13 gb) unsaturated polymer synthesis i) polyisocyanate, in 15 molar equivalents ii) polyol, in molar equivalents iii) acrylate, in molar equivalents 20 iv) catalyst v) inhibitor vii) solvent in% viii) temperature / hour ° C / hour ix) viscosity 25 x)% non volatile material, in fact theoretical c) additive ig Free radical initiator (Part II) 30 a) Peroxide component 2.4% tert. butyl hy- 2.4% tert.

dropper oxide butyl hydroperoxide b) catalytic component SO2 gas SO2 gas

Gassing time, p 0.5 1 35 Purging time, p 15 10

Trækstvrke. MPa at the take out of box 0.33 0.90 3 hours ^ 24 hours 15 DK 170553 B1

Binder level (Part 1 + peroxide component) 2% 2% cast metal shaking% 5 Example 8 9

Sand Wedron 5010 Port Crescent

Part I

a) unsaturated monomer acrylic acid 3.2 g diethylene glycol diacrylate 21.4 10 g, trimethylol propane trimethacrylate 19.8 gb) unsaturated polymer synthesized as the same as in Example 4 described below 40 g 40 g 15 i) polyisocyanate in molar equivalents TDI, 3 ii) polyol, in molar equivalents Olin 20-265, 1 iii) acrylate, in molar hydroxyethyl acryl 20 lat, 4 iv) catalyst dibutyltin dilaurate, 0.14% v) inhibitor hydroquinone monomethyl ether 0.07% 25 vii) solvent pentoxone (93.7) in% hydroxyethyl acrylate 35% viii) temperature / time 40 ° - 45 ° for 2 hours ° C / hours thereafter 20 ° C - 85 ° C for 4 30 ix) thixotropic viscosity after 3 days x )% non-volatile material, in fact 63.1 theoretical 65 35 c) additive vinylsilane vinylsilane A-172 2.0g acrylic acid 1.6g

Free radical initiator (Part II) a) Peroxide component (90%) tert.butyl tert.butyl peracetate 40 hydroperoxide (6 g) 2.2% b) Catalytic component SO2 gas heat 450 ° for 90 s.

Gassing time, s 0.5

Purging time, page 15 with N2 16 DK 170553 B1

Tensile strength, MPa when removing box 0.37 0.52 3 hours 0.37 24 hours 0.64 5 cold strength 1.07 1.10

Binder Level (Part I + Peroxide Component) 2% 2% Cast Metal Shaking% * 10 Example 10 11

Sand Wedron 5010 Wedron 5010

Part I, same as in Example 10 a) unsaturated monomer acrylic acid 1.6 g, trimethylol propane triacrylate 9.9 gb) unsaturated polymer synthesized as described below, 20 g 20 unsaturated polymer synthesis i) polyisocyanate molar equivalents TDI, 3.5 ii) polyol, in molar glycerol diethylene equivalents glycol mixture (1: 1), 1 iii) acrylate, in molar hydroxyethylacry equivalents lat 4.5 iv) catalyst dibutyltin dilaurate 30 0.14% v) inhibitor hydroquinone monomethyl ether 0.07 % vii) solvent ethylhexyl acrylate in% + hydroxyethyl acrylate (4: 6) 40% viii) temperature / time 40 ° - 45 ° for 2 hours ° C / hours thereafter 80 - 85 for 4.8 hours ix) viscosity 10 St 40 x)% non-volatile material, actually 59.9 theoretical 60.0 c) Additive vinylsilane A-172, 2 "HiSol" ®) 10 45 10.7

Free Radical Initiator (Part II) 17 a 170% tart peroxide component. butyl hydroperoxide 2.2% b) catalytic component SO2 gas 1/2 SO2 gas in N2 carrier gas

Gassing time, s 0.5 1/2

Penetration time, s 15 with N2 gas none

Tensile strength. MPa when taking box 1.57 0.48 10 3 hours 1.57 0.84 24 hours 1.77 1.54

Binder level (Part I + peroxide component 2% 1.5 cast metal aluminum 15 shaking% 100

Example 12

Sand Wedron 5010

Part I

a) unsaturated monomer acrylic acid 1.6 g, diethylene glycol 5.49, 20 trimethylol propane triacrylate 9.9 b) unsaturated polymer synthesized as described below, 20 g unsaturated polymer synthesis 25 i) polyisocyanate molar equivalents 4 ii) polyol, in molar equivalents glycerol Iii) acrylate, in molar equivalents of hydroxyethyl acrylate iv) catalyst dibutyltin dilaurate 0.14 v) inhibitor hydroquinone monomethyl ether 0.03 vii) solvent methylisoamyl ketone, "HiSol" ® 10% (65:35) 35% - 35 viii) temperature time 40 ° - 45 ° for 1.75 hours then ° C / hour 80 ° - 85 ° for 4.5 hours ix) viscosity, St 10 x)% non volatile material, in fact 64.1 40 theoretical 65 c) additive ig vinylsilane 2.0 "HiSol" ® 5.3

Free radical initiator (Part II) 18 a) Peroxide component 2.2% tert. butyl hydroperoxide - 70 b) catalytic component 1% SO2 gas in N2 carrier gas

Gassing time, s 20 ^ 5 Penetration time, s none

The drag of the drag. MPa $ at box take 1.50 3 hours 1.08 24 hours 1.61 10 Binder level (Part I + peroxide component) 1.5 cast metal aluminum shaking% 100

Example 13 15 Sand Wedron 5010

Part I

a) unsaturated monomer acrylic acid 1.6 g, diethylene glycol 5.49, trimethylol propane triacrylate 9.9 b) unsaturated polymer synthesized as described below, 20 g unsaturated polymer synthesis i) polyisocyanate molar equivalents 4 ii) polyol, in molar equivalents glycerol Iii) Acrylate, in molar equivalents of hydroxyethyl acrylate iv) Catalyst dibutyltin dilaurate 0.14 v - 45 ° C for 1.75 hours thereafter ° C / Hours 80 ° - 85 ° C for 4.5 hours 35 ix) Viscosity, St 10 x)% non volatile material, actually 64.1 in theory 65 c) Additive ig vinylsilane 2.0 "HiSol" ® 5.3

Free radical initiator (Part II) 19 a) Peroxide component 2.2% tert. butyl hydroperoxide - 70 b) catalytic component SO2 gas

Gassing time, s 0.5 5 Blowing time, s 15 with air

Tensile strength, MPa when taking box 1.22 3 hours 0.66 24 hours 1.03 10 Binder level (Part I + peroxide component) 1.5 cast metal aluminum shaking% 100 Particularly preferred embodiments of the 15 processes defined in the claims can be summarized as follows :

In the mold forming process, the aggregate material is preferably sand. By the same process, the catalytic agent is gaseous sulfur dioxide. The catalytic agent is conveniently suspended in a carrier gas and exposed to the binder material for at least 20 0.5 seconds. Furthermore, the catalytic agent may have an elevated temperature of at least approx. 50 ° C.

In the process of claim 1, the binder material may comprise a mixture in which the monomer is mixed with at least one other ethylenically unsaturated monomer. Furthermore, the binder material may comprise at least one ethylenically unsaturated polymer in addition to the monomer. Conversely, in the process of claim 3, the ethylenically unsaturated polymer in the binder composition may be blended with at least one ethylenically unsaturated monomer or at least one other ethylenically unsaturated polymer. The unsaturated polymer can e.g. be an oligomer 30 or an adduct.

In the process of bonding at least two materials, the catalytic agent is preferably of a chemical nature, e.g. gaseous sulfur dioxide, or elevated temperature of at least approx. 50 ° C. The catalytic agent is conveniently suspended in a carrier gas, and exposed to the binder material for at least 1/2 second.

In the process of claim 5, the monomer in the binder material is preferably mixed with at least one other ethylenically unsaturated monomer or at least one ethylenically unsaturated polymer.

Claims (11)

A process for forming molds and molds comprising a) distributing on a molding aggregate material a binding amount of a binder material, said binder material comprising an ethylenically unsaturated monomer and / or polymer, b) forming the aggregate material for the desired molding, and c) polymerization of the binder material by a free radical initiator, which initiator comprises an organic peroxide and a catalytic agent, characterized in that the catalytic agent is gaseous sulfur dioxide. Process according to claim 1, characterized in that the binder material comprises an ethylenically unsaturated acrylic monomer and / or acrylic polymer. Process according to claim 1 or 2, characterized in that the binder material comprises an acrylic polymer selected from the group consisting of pentaerythritol triacrylate, trimethylolpropane triacrylate, 1,6-hexanediol diacrylate and tetraethylene glycol diacrylate. Process according to any one of claims 1-3, 30, characterized in that the binder material comprises a monomer mixture of at least one other ethylenically unsaturated monomer. DK 170553 B1 Process according to any one of claims 1-3, characterized in that the binder material comprises a polymer blend of at least one other ethylenically unsaturated polymer. In the process, for example, the unsaturated polymer may be an oligomer or an adduct. In the process of casting light metal items, the preferred embodiments given above also apply here, ie. in forming the molding. Process according to any one of claims 1-5, characterized in that the binder material comprises a mixture of at least one other ethylenically unsaturated monomer and at least one other ethylenically unsaturated polymer. Process according to any one of claims 1-6, characterized in that the unsaturated polymer is an oligomer. Process according to any one of claims 1-7, characterized in that the unsaturated polymer is an adduct. Process according to any one of claims 1-8, characterized in that the catalytic agent is suspended in a carrier gas and exposed to the binder material for at least 0.5 second. Process according to any of claims 1-9, characterized in that the aggregate material is true. 10 PATENT REQUIREMENTS Use of moldings and molds formed by a method according to any one of claims 1-10 for casting light metal blanks.