IE50414B1 - Process of binding particulate materials and especially foundry aggregate to form foundry cores and moulds - Google Patents

Abstract

To form a shaped foundry core or mould, a binder material comprising an ethylenically unsaturated monomer or polymer is distributed on a foundry aggregate, the aggregate is shaped into the desired foundry article, and the binding material is then polymerised by means of a free radical initiator comprising a peroxide and catalytic agent. The binding material is preferably a solution of an ethylenically unsaturated polymer in a solvent of unsaturated monomeric compound or compounds, in which vinyl or acrylic unsaturation is present. This binder is suitable as a foundry binder of the cold box type wherein a room temperature, rapid gas cure is utilized. The gas, preferably sulfur dioxide, serves as the catalytic agent of the free radical initiator. Alternatively the catalytic agent may be heat. The binder collapses readily after casting of aluminium and other lightweight metals to provide complete shakeout of the core with minimum application of external energy.

Description

This invention relates to processes for binding together particulate materials generally, and to the specific instance of binding foundry aggregate to form foundry cores and moulds for use in the casting of metals, more particularly 1ightweight metals.

Many different types of binding materials have found use in foundry core making and mold making operations. The binding material upon hardening should impart to the core and molds various desirable properties. Examples of such properties are erosion resistance, humidity resistance and collapsibility or shake-out. In core making or mold making, high production is also a desired goa 1.

Modern core making and mold making techniques began with the use of unsaturated drying oils derived from natural products as binding material. Linseed oil is the foremost example; ofdrying oil. On exposure to air, ‘ s . linseed oil and other unsaturated oils undergo oxidatively initiated polymerizations resulting in formation of solid, highly cross-linked structures.

PolymeTiz.jtiio.n ba’nlb^e accelerated by heat or by chemical - 3 methods. These binding materials are known in the industry as core oils. In forming a core, the oil is mixed with sand and the sand mixture is shaped into the form of a core or mold. Hardening is accomplished by heating or ageing the core or mold for a long period of time. Binders based on core oil, in addition to the oil component, may contain other components such as oil derived esters, unsaturated hydrocarbon resins and solvents. Core oil based processes for forming foundry shapes such as molds and cores have been known for fifty to sixty years.

Processes which are faster than the abovementioned core oil processes were introduced 25 to 30 years ago. These processes require heat cure for the binding material. These hot-box core processes are based upon thermal setting resin compositions. Chemically these thermosetting resins include phenol-formaldehyde resins, ureaformaldehyde resins and furfuryl alcohol-formaldehyde resins. In addition to using heat to cure or polymerize these binding materials, acids are often incorporated as catalysts.

About ten years ago room temperature, high speed processes for the production of foundry cores and molds were introduced. The binder formed by these processes is based on urethane chemistry. In essence, the binding material consists of two liquid resin components. One component is a phenol-formaldehyde resin. The second component is a polymeric isocyanate. The phenolic and the isocyanate resin are mixed with sand and may be used in either a cold box or a no bake system. In the cold box system, the sand which has been coated with the two components is blown into a core box. Once the sand mixture is blown into a core box a gaseous tertiary amine is passed through the core box to cause an instantaneous cure or solidification to form the binder. U.S. Patent No. 3,409,579 is illustrative of this technology. In no bake type core making procedure the polyisocyanate component, the phenolic resin component and a catalyst are all mixed with sand at the same time. The sand mix is then poured into a core box or pattern. The sand mix remains fluid for a period of time. After this period has elapsed, the catalyst initiates the curing or polymerization and the core is rapidly formed as the binding components quickly react to form a urethane binder. No bake binders are taught by U.S. Patent No. 3,676,392.

A further binding composition and procedure for forming a foundry binder is described in U.S. Patent No. 3,879,339. In this patent there is described a cold box, i.e., room temperature, gas curable method of forming a foundry binder involving an organic resin - 5 which is acid curable and an oxidizing agent. This binding component is cured with sulphur dioxide gas.

The combination of sulphur dioxide plus the oxidizing agent, leads to the formation of sulfuric acid, the acid serves to cure the acid curable organic resin. In essence, sulphuric acid is formed in situ and the acid reacts with the resin. Thus curing of the binding composition is accomplished.

None of the above described foundry binders are of such utility and versatility that they are viewed as a universal or irreplaceable foundry binder. Each has advantages and disadvantages to some degree.

Therefore it is an object of the invention to provide a process employing a new binder based upon chemistry heretofore not applied in foundries or in the like fields of particle binder use.

According to the present invention, a process for forming shaped foundry articles comprises: (a) distributing on a foundry aggregate a binding amount of a binder material, said binder material comprising an ethylenically unsaturated monomer or polymer; - 6 (b) shaping the aggregate into the desired foundry article, and (c) thereafter non-anaerobically polymerizing the binder material by means of a free radical initiator comprising an organic peroxide by application of heat and/or a catalytic agent.

In another aspect, the invention provides a process for binding at least two particulate materials in which the binder causes the particulate materials to cohere adequately for metal casting to take place in contact therewith but allows the materials to separate readily enough thereafter for shake-out to be effected, which process comprises: (a) distributing on at least one of said materials a binding amount of a binder material, said binder material comprising an ethylenically unsaturated monomer or polymer; (b) bringing the materials to be bound together into contact, and (c) thereafter non-anaerobically polymerizing the binder material by means of a free radical initiator comprising an organic peroxide by application of heat and/or a catalytic agent.

Thus, the invention relates to binding processes of the type in which particulate materials are aggregated together by a curable binder to form a coherent mass, and a particular feature is that the curing of the binder is effected by the application of heat or a catalytic agent but not until after the materials have been shaped or mixed. It is therefore distinguished from former processes in which the particulate material to be aggregated is divided into two portions and one component of a binder composition is mixed with one portion while another component of the binder composition is mixed with the other portion, with curing commencing as soon as mixing of the two portions begins. The preferred process involves room temperature curable binder compositions which are polymerizable through free radical initiation and chain extension. The compositions are capable of binding sand or other aggregates to form moulds or cores for casting metals, including especially aluminium and other lightweight metals. Moulds and cores made using these binders demonstrate superior collapsibility when used in casting lightweight metals, i.e., metals which are cast at low casting temperatures. The curing of the binder material to form the coherent aggregate preferably takes place at ambient temperature and is accomplished by a free radical initiator S0414 - 8 comprising a peroxide and a catalytic agent. In the preferred process, the catalytic agent is gaseous and the cure or hardening is nearly instantaneous. However, selection of differing catalytic agents results in a variety of options for the manner and rate of cure.

The chemistry appertaining to the foundry binder is different from that appertaining to previous binders that have heretofore been recommended for use in the foundry industry. The binder also has application as a binder or binding agent in fields other than the foundry industry. The chemistry on which this binder is based is analagous to a degree to chemistry which has heretofore been utilized in coatings, see for example, British patent No. 1,055,242, and adhesives, see for example various patents assigned to Loctite Corporation. An anaerobically cured foundry binder based on similar chemistry is described in Canadian Patent No. 1,053,440. This binder cures very slowly and involves the necessity of heating to accomplish cure. Applicant's invention does not encompass an anaerobic curing process and involves rapid, almost instantaneous, curing at room temperature with certain catalytic agents.

It is well known that foundry shapes, that is cores and molds are formed by disbursing on sand or another aggregate material a binding substance or chemical, - 9 shaping the sand into the desired shape and allowing or causing the binder substance or chemical to harden to form a binder. The present invention can be thought of in terms of a binder which results from bringing together two parts. Part lisa binding substance or composition which undergoes polymerization and crosslinking to adhere, hold or bind the sand or other aggregate in the desired shape. The second part (Part II) is an agent which causes the polymerization and crosslinking of Part I to take place. This agent is referred to herein as the free radical initiator. As used in this description the term crosslink indicates a chain build up which results when a polymer is involved either by linking with another polymer or with a monomer. The term polymerization includes “crosslink but also applies to the chain extension which involves only monomers.

Part I of the binder system can be described as an unsaturated composition which is crosslinkable or polymerizable by free radical mechanism, The unsaturation is preferably terminal or pendent. Still internal unsaturation is acceptable and polymerization will result upon combination with Part II. It is also feasible, depending upon the manner of synthesis of the Part I component, to have a Part 1 component having both terminal and/or pendent unsaturation and also internal - 10 unsaturation in the same component. Applicant's believe the polymerization mechanism is nearly all of the free radical type when crosslinking compositions (i.e., unsaturated polymer(s)) are involved. When certain monomers are used as the binding composition it is possible that a portion of the polymerization may take place by a mechanism other than free radical. It is to be understood therefore that the description contained herein sets forth applicant's best belief as to the mechanism for polymerization and that free radical mechanism is used for convenience and accurately describes such mechanism in nearly all instances. 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. Curing is accomplished using Part II, a free radical initiator, which comprises a peroxide and a catalytic agent. It has been discovered that unsaturated reactive monomers, polymers and mixture thereof (i.e., the binding composition) can be used as a binding material which is instantaneously curable upon selection of certain catalytic agents for the free radical initiator. The unsaturation found in the monomers and polymers is preferably of the ethylenic type. For example reactive polymers, which can also be described as oligomers or as adducts, which contain preferably vinyl or acrylic unsaturation are used as binding - 11 compositions which upon polymerization make a binder for foundry cores or molds from sand. The free radical initiator (Part II) is mixed with the reactive polymer or monomer (Part 1) and forms free radicals which polymerize the binding composition to form the binder. This combination of a peroxide and a catalytic agent, which agent in addition to being chemical in nature may also be a form of energy, is referred to herein as a free radical initiator.

The free radical initiator described herein can be used to cause polymerization of Part I materials in a number of manners. For example, the peroxide can be mixed with the Part I material and this mixture dispersed uniformly on sand. After the sand is shaped as desired, the shaped sand can be exposed to the catalytic agent. Alternatively, the catalytic agent can be added to the Part I material and this mixture used to coat sand and the coated sand then shaped as desired. The peroxide component of the free radical initiator can then be added to the shaped article and hardening through polymerization will occur. It is also possible to divide the Part I material into two portions. The catalytic agent could be added to one portion and the peroxide could be added to the second portion. Upon combining the two portions, after applying at least one portion to the material to be bound, polymerization occurs. Selection - 12 of various catalytic agents has a large influence upon the means that can be used to polymerize the binding material and upon the rate at which the binding material is cured. For example, selection of the proper catalytic agent enables the user of the binding material to instantaneously polymerize the material at room temperature or to delay the polymerization for some time and finally achieve polymerization at elevated temperatures. The availability of options for selecting conditions at which the binding composition polymerizes is deemed significant.

As described above, the Part I binding material is a polymerizable, unsaturated, monomer, polymer or mixture of such monomer(s) and such polymer(s). Examples of materials which are suitable monomeric compounds for the Part I component include a wide variety of monofunctional, difunctional, trifunctional and tetrafunctional acrylates. A representative listing of these monomers includes alkyl acrylates, hydroxyalkyl acrylates, alkoxyalkyl acrylates, cyanoalkyl acrylates, alkyl methacrylates, hydroxyalkyl methacrylates, alkoxyalkyl methacrylates, cyanoalkyl methacrylates, N-alkoxymethylacrylamides, and Nalkoxymethylmethacrylamides. Difunctional monomeric acrylates include hexanediol diacrylate and tetra25 ethylene glycol diacrylate. Other acrylates which can be used include trimethololpropane triacrylate, - 13 methacrylic acid and 2 ethylhexylmethacryl ate. It is preferred to use poly functional acrylates when the monomer is the only binding species in the binder system. As previously mentioned when only monomers are used as the binding material crosslinking may not occur. Also some mechanism beside a free radical mechanism may cause polymerization.

Examples of unsaturated reactive polymers which have been found to be especially useful in forming this foundry binder are epoxy acrylate reaction products, polyester/urethane/acrylate/reaction products, polyether acrylates, and polyester acrylates. Unsaturated polymers which find use as a Part I composition include commercially available materials such as UVITHANE 782 and 783, acrylated urethane oligomers from THIOKOL (Registered Trade Mark) and CMD 1700, an acrylated ester of an acrylic polymer and CELRAD 3701, an acrylated epoxy resin both available from Celanese. Reactive polymers can be formed in a number of manners. One preferred method of preparation of the reactive polymers is to form an isocyanate terminated prepolymer by reacting a polyhydroxy compound or polyol with a di isocyanate. The prepolymer is further reacted with a hydroxyalkyl acrylate to form an oligomer. A second approach which has been found to be beneficial is to react a polyisocyanate compound, preferably a 41 4 - 14 diisocyanate compound, with an hydroxyalkyl acrylate.

The reaction product is an adduct of these two materials. In addition oligomers and adducts may be prepared simultaneously under appropriate conditions.

In addition to the reactive unsaturated polymer, a solvent, preferably of a reactive nature, may be included and preferably is included as a component of the binding material. Depending upon 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 recitation or monomer Part I materials. Accordingly the Part I material may comprise a mixture of those unsaturated monomers and unsaturated polymers which have previously been suggested for use as Part I materials per se. Best results occur when a solution of an unsaturated reactive polymer and a monomeric unsaturated solvent is used.

This combination appears to be more readily capable of copolymerization and crosslinking to form a binding matrix required either to adhere sand or other aggregates together thereby forming the foundry core or mold or to bind other materials.

As stated, it is preferred to use in Part I of the binder system an unsaturated monomeric compound as solvent in addition to the unsaturated polymer. As described above - 15 these monomers contain unsaturation and are crosslinkable with the polymer in addition to serving as a solvent for the unsaturated polymer, Any of the unsaturated monomers (or combination thereof) which were 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 favored monomers, to be used as solvents for the unsaturated polymers, include pentaerythritol triacrylate, trimethylolpropane triacrylate, 1,6-hexanedioT diacrylate, and tetraethylene glycol diacrylate which is used as a solvent for the unsaturated polymer. The amount of monomer in Part I can be 0 up to 100% based upon the total weight of Part I binding composition.

It is possible to use the reactive polymer as the Part I material and the free radical initiator without any solvent, Including unsaturated monomer, being present for the unsaturated polymer. It is also feasible to use the unsaturated monomer as the Part I material with a free radical initiator but without the reactive polymer in order to get a polymerized binder. Neither of the two above described combinations are preferred. As previously stated the preferred binder system is Part I comprising a reactive unsaturated polymer dissolved in a reactive diluent, preferably a monomeric unsaturated solvent and Part II comprising a free radical initiator.

SO 4 1 4 - 16 The free radical initiator is comprised of two components The first component is preferably an organic peroxide. However, it is contemplated that any substance employed as the first component which will form free radicals upon exposure to a catalytic agent, could be used with the free radical polymerizable Part I binding material unsaturated polymers, monomers and mixtures thereof described above. Peroxide level can vary over wide limits depending to some extend upon the catalytic agent used. However, in general it can be said that 0.5% to 2% peroxide based upon the weight of the binding material (Part I) will produce satisfactory binding under most conditions. Examples of preferred peroxides include t-butyl hydroperoxide, cumene hydroperoxide and methyl ethyl ketone peroxide. It is worthy of note that hydroperoxides are much preferred over peroxide. Inconsistent curing has been observed using peroxide. Mixtures of peroxides and hydroperoxides and mixtures of hydroperoxides are useful.

The catalytic agent component of the free radical initiator is preferably chemical in nature, preferably sulfur dioxide in gaseous form. Other chemical catalytic agents which are thought to have some practical utility include amines and NOg. Once again it should be noted that a change of the catalytic agent can have a vivid influence upon the rate of polymerization. However, - 17 other non-chemical agents which interact with the peroxide component of the free radical initiator may also be of utility. For example, heat, at a temperature of at least 125°F (52°C) and more preferably 140°F (60°C), can act upon peroxide to form free radicals which serve to polymerize the Part I materials. Increasing the temperature tends to increase the polymerization and cause faster cure. The polymerization takes place without the presence of a chemical catalytic agent.

In preferred foundry 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 mix is then formed into a desired foundry shape by ramming blowing or other known foundry core and mold making methods. The shaped article is then exposed to the catalytic agent component of the free radical initiator. In the preferred method of this Invention gaseous S02 is used as the catalytic agent of the free radical initiator.

This gas is present only in catalytic amounts as previously stated. The exposure time of the sand mix to the gas can be as little as 1/2 second or less and the binder component cures on contact with the catalytic agent. When S02 is used as the catalytic agent in a foundry cold box process it is suspended in a stream of carrier gas in a known manner. The carrier gas is 0 414 - 18 usually Ν2· As little as 0.5% S02 based upon the weight of the carrier gas is adequate to cause polymerization.

It is also feasible to expose S02 to the binder component without the presence of any carrier gas.

Part I may also contain optional ingredients. For example additives for wetting and defoaming may be useful. Silanes have been found to be especially useful additives. Especially preferred are unsaturated silanes, for example vinyl silanes.

Advantages of this binding composition as a foundry binder are the following. The collapsibility of the binder used for casting aluminium is excellent. It has been found that this binder will readily collapse or shake out of an aluminum casting with the application of a minimum of external energy. The binder also provides good strength properties. The bench life of sand mixed with Part I is lengthy. The surface finish of castings made using this binder and process has been found to be very good. The production rate of cores and molds made using this binder system is rapid especially when S02 gas is used as the catalytic agent.

A foundry utilizing the binder composition which is described herein will mix Part I and one component of the free radical initiator, preferably the peroxide, - 19 with sand or other suitable foundry aggregate in a known manner. The sand mix is then formed into the desired foundry shape, cores or molds, in known manner. The sand mix is then exposed to the second component of the free radical initiator, preferably the catalytic agent which is preferably sulfur dioxide gas, and polymerization of the Part I binding material immediately occurs to form the binder of this invention.

The present invention is further illustrated by the 10 following examples in which, unless otherwise indicated, all parts are by weight and all percentages are weight percentages.

EXAMPLE I Gel tests were conducted on various unsaturated monomers 15 and polymers to determined their tendency to polymerize and the speed of polymerization. In carrying out the tests from about 1.5 to 2 grams of unsaturated monomer or polymer (i.e. Part I) were mixed with 0.03 grams of t-butylhydroperoxide (the peroxide component of the free radical initiator). This mixture was then exposed to SOg gas (the catalytic agent of the free radical initiator) either by dispersing the gas in the liquid (bubbling) or by creating an SOg atmosphere above the liquid (contacting). The results, set forth below, 0 414 - 20 indicate that all unsaturated monomers and polymers polymerize. Thus all the listed compounds are potential binders. Those listed compounds which demonstrated rapid polymerization or gelling are of greatest potential foundry binder use in foundry high speed cold box mold and core making rapid.

PART I Acrylic Acid Ethyl Acrylate n-Butyl Acrylate Isobutyl Acrylate 2-Ethylhexyl Acrylate Isodecyl Acrylate 2-Ethoxyethyl Acrylate Ethoxyethoxyethyl Acrylate Butoxyethyl Acrylate Hydroxyethyl Acrylate Hydroxypropyl Acrylate Glyeidyl Acrylate Dimethyl ami noethyl Acrylate Cyanoethyl Acrylate Diacetone Acrylamid i n Methanol, 50% Acrylamid in Methanol, 50% (N-Methylcarbamoyloxy)ethyl Acrylate FINDING OF POLYMERIZATION Rapid, on contact wi th SO S1 ow, on contact with so2 Slow, on contact ' with so2 Slow, on contact i with so2 Rapid, on contact with SO, Rapid, on contact with SO, Rapid, on contact with SO. Rapid, on contact wi th SO. Rapid, on contact with so. Rapid, on contact with so. Rapid, on contact with so. Rapid, on contact with so. Rapid, on contact with so. Rapid, on contact with so. Rapid, on contact with so. Rapid, on contact with so. Rapid, on contact with so. - 21 - Methylcellosolve Acrylate Rapid, on contact with so2 Phenoxyethyl Acrylate Rapid, on contact with so2 Benzyl Acrylate Rapid, on contact with so2 Ethylene Glycol Acrylate Phthalate Rapid, on contact with so2 Melamine Acrylate Rapid, on contact with so2 Diethylene Glycol Diacrylate Rapid, on contact with so2 Hexanediol Diacrylate Rapid, on contact with so2 Butanediol Diacrylate Rapid, on contact wi th so2 Triethylene Glycol Diacrylate Rapid, on contact wi th so2 Tetraethylene Glycol Diacrylate Rapid, on contact wi th so2 Neopentyl Glycol Diacrylate Rapid, on contact with so2 1, 3-Butylene Glycol Diacrylate Rapid, on contact with so2 Trimethylolpropane Triacrylate Rapid, on contact with so2 Pentaerythritol Triacrylate Rapid, on contact with so2 Methacrylic Acid Rapid, on contact with S02 Methyl Methacrylate Slow, on bubbling with S02 2-Ethylhexyl Methacrylate Slow, on bubbling wi th S02 Hydroxypropyl Methacrylate Rapid, on contact with so2 Glycidyl Methacrylate Rapid, on contact with S02 Dimethyl ami noethyl Rapid, on contact with so2 Methacrylate - 22 Ethylene Glycol Dimethacrylate Trimethylolpropane Trimethacrylate Acrylated urethane derived 5 from glycerine 65% in MIAK/HiSol-10 N-Methylol Acrylamid in water 60% N-Qisobutoxymethyij Acrylamid in Methanol 50% Epocryl R-12 Resin (Shell) Acrylated Epoxy 80% in Acetone UVITHANE 783 (Thiokol/Chem.

Div.) Acrylated Urethane 01i gomer AROPOL 7200 (ASHLAND) unsaturated polyester resin in Acetone 50% RICON 157 (Colorado Specialty Chemical) an unsaturated hydrocarbon resin in acetone 50% Hydroxy PBG-2000 (Hystl Co.) an unsaturated hydrocarbon resin in acetone 50% Rapid, on contact with SO Rapid, on contact with SO Rapid, on contact with SO Rapid, on contact with S02 Rapid, on contact with S02 Slow, on contact with S02 Rapid, on contact with S02 Slow, on contact with S02 Slow, on contact with S02 Slow, on contact with S02 EXAMPLE II An unsaturated polymer was prepared by reacting the equivalent of 1 mole of pentane diol and the equivalent - 23 of 4 moles of hydroxyethyl acrylate with the equivalent of 3.0 moles of toluene di isocyanate. Dibutyltin dilaurate was used to catalyze the reaction. Based on the solids contents 0.14% catalyst was used. Hydroquinone monoethyl ether is used as an inhibitor. The reaction was carried out in a reaction medium (solvents) consisting of ethylhexyl acrylate and hydroxyethyl acrylate. In carrying out the reaction a mixture of TDI and solvent is charged to a reaction vessel. Pentane diol is added to this mixture followed by the addition of hydroxyethyl acrylate. When the addition of hydroxyethyl acrylate is complete catalyst is added. The reaction is carried out under an air sparge. The reaction proceeded at 40 to 45°C for 2.1 hours and then the temperature was raised to 80-85°C and the reaction was continued 4.3 hours, then 0.03% inhibitor is added and the reaction continued one-half hour. The product was allowed to cool. The product was tested for nonvolatiles and 59.2% were found. This corresponded to a theoretical amount of nonvolatiles of 60%. The viscosity of the product was 6.0 stokes. 20 grams of the unsaturated polymer was then blended with 1.6 grams of acrylic acid, 10.7 grams of diethylene glycol diacrylate, 9.9 grams of trimethylolpropane trimethacrylate and 2.0 grams of vinyl silane. Acrylic acid, diethylene glycol diacrylate and trimethylol propane triacrylate are unsaturated monomers. This solution of - 24 unsaturated polymer and unsaturated monomers is referred to as Part I. One gram of t-butylhydroperoxide, the peroxide component of the free radical initiator, was added to the solution of unsaturated polymer and unsaturated monomers.

Wedron 5010 sand (washed and dried fine grained silica sand, AFSGFN 66) was placed in a suitable mixing apparatus. Part I and the peroxide component of the free radical initiator were admixed with the sand until a uniform distribution was achieved. The level of Part I plus peroxide is two per cent (2%) based upon weight of sand.

The sand mix was blown into a conventional core cavity or box for making standard tensile briquettes test cores known as dog bones. The dog bone test cores were cured by exposing the cores to the catalytic component of the free radical initiator. The catalytic component is gaseous sulfur dioxide. The cores were exposed to the S02 catalyst for approximately 1/2 second (gas time) and the catalyst was removed by purging with nitrogen for 15 seconds and the core removed from the box.

Tensile strengths of the core in psi were 223 (1527 x 10 N/m2) out of the box, and 205 (1404 χ 103 N/m2) after 3 hours and 227 (1555 χ 103 N/m2) after 24 hours. - 25 Dog bone cores similar to those described above were used in shakeout studies with aluminum castings. Seven tensile briquettes (dog bones) were arranged in a mold. The mold incorporated a gating system. The mold is designed to provide hollow castings having a metal thickness of approximately one-quarter inch (0.6 cm) on all sides. An opening at an end of the casting is provided for removal of the core from the casting.

Molten aluminum at approximately 1300°F (704°C) prepared from aluminum ingots was poured into the mold. After cooling for about an hour the aluminum castings are broken from the gating system and removed from the mold for shake-out testing.

Shakeout tests are performed by placing a casting in a one gallon container. The container is placed on an agitating mechanism and tumbled for 5 minutes. The weight of the sand core which is removed from the casting in this manner is compared to the initial weight of sand core and a percent shake-out is calculated. Sand remaining in the casting after the agitation described above is removed by scraping and also weighed. The sand core, bonded with the binder described above, was observed to have 100 shakeout. It should be noted that the shakeout test above described is not a standard test. Applicants are not aware of any standard test to measure this quality. It is submitted that the test - 26 used is valid for gaining collapsibility of a binder relative collapsibi1ity of are subject to a degree of indicators.

EXAMPLE Sand n understanding of the and for comparing the binders. The percents given variance but are reliable Wedron 5010 at 74 to 78°F (23-26°C) PART I a) unsaturated monomer b) unsaturated polymer acrylic acid 1.6 grams diethylene glycol diacrylate 10.7 grams trimethylolpropane trimethacrylate 9.9 grams.

Synthesized as described below 20 grams. unsaturated polymer synthesis i) polyisocyanate, in 20 mole equivalent i i) polyol, in mole equivalent iii) acrylate, in mole equivalent TDI 4 Glycerine - 1 hydroxyethyl acrylate, 5 iv) catalyst v) inhibitor vi) solvent in % vii) temp/time °C/hr. viii) viscosity, stokes ix) % Nonvolatiles 10 actual theoreti cal c) additive in grams Free Radical Initiator (Part II) a) peroxide component b) catalytic component Gas time, sec.

Purge time, sec.

Tensile Strength,psi 20 out of box hr. hr. dibutyltin dilaurate 0.14% hydroquinone monomethyl ether ethylhexyl acrylate and hydroxyethyl acrylate, 40% 40° to 45° for 2.13 hrs. then 80° to 85° for 4.8 hrs. 16.0 63.9 60.0 vinyl silane - 2.0 2.2% t-butylhydroperoxide S02 gas 0.5 with N2 178 (1219 χ 103 N/m2) 217 (1486 x 103 N/m2) 233 (1596 χ 103 N/m2) S0414 - 28 Binder level (Part I + 2% peroxide component) Metal Cast Shakeout % Aluminum 100 EXAMPLE 4 Sand Hedron 5010 Hedron 5010 PART I a) unsaturated monomer Acrylic acid 1.6 grams diethylene glycol diacrylate 10.7 grams trimethylolpropane triacrylate 9.9 grams Hydroxyethyl acrylate 2.2 grams, dicyclopentenyl acrylate 20.8 grams (N-Methylearbamoyloxy)ethyl acrylate 17.3 g. b) unsaturated 15 polymer Synethesized as described below, 20 grams unsaturated polymer synthesis 1) polyi socyanate, in mole equivalent TDI, 3 ii) polyol, in mole Olin 20-2655),1 equivalenta)polyoxypropylene glycol iii) acrylate, in hydroxyethyl mole equival ent acrylate, 4 iv) catalyst dibutyltin dilaurate, 0.14% v) i nhibi tor hydroquinone monomethyl ether vi) solvent in % ethylhexyl acrylate and hydroxyethyl acrylate, 40% vi i) temp/time 40° to 45° for 2.1 °C/hr. thru 80° to 85° for 4.75 vi i i) viscosi ty 4.2 ix) % Nonvolatiles actual 59.2 theoretical 60.0 c) additive in gram Vinyl silane 2.0 grams Free Radical Initiator (Part II) a) peroxide component 11.3% cumene hydro- 2.4% t-butylperoxide. hydroperoxide. - 30 - b) catalytic component so2 gas SOg gas Gas time, sec. 0.5 1 Purge time, sec. 15 with N2 15 with Ng Tensile Strength, psi out of box 160 (1096 x 103 N/m2) 3 hr. 25 (171 x 1 N/m2) 24 hr. 48 hr. 232 (1589 x 103 N/m2) Binder level (Part 1+ peroxide component) 2% 2% Metal Cast Aluminum Shakeout % 100 EXAMPLE 6 7 Sand Wedron 5010 Wedron 5010 PART I a) unsaturated monomer Pentaerythritol acrylic acii - 31 triacrylate 40 grams diethylene glycol diacrylate 21.4g, trimethylolpropane triacrylate 13g. b) unsaturated polymer synthesis υ polyisocyanate, in mole equivalent ii) polyol, in mole equivalent i i i) acrylate, in mole equiv- al ent iv) catalyst v) inhibitor vi) solvent in % vi i) temp/time °C/hr. viii) viscosity ix) % Nonvolatiles actual theoretical c) additive in gram Free Radical Initiator (Part II) 0 414 a) peroxide component 2.4% t-butylhydroperoxide. 2.4% t-butylhydroperoxide. b) catalytic component S02 gas S02 gas Gas time, sec. 0.5 1 Purge time, sec. 15 10 Tensile Strength, psi out of box 3 hr. 24 hr. 48 (329 χ 103 N/m2) 130 (890 χ 103 N/m2) Binder level (Part 1 + peroxide component) 2% 2% Metal Cast Shakeout % EXAMPLE Wedron 5010 Port Crescent Sand Part (I) a) unsaturated monomer Acrylic acid 3.2g, - 33 diethylene glycol diacrylate 21.4g, trimethylolpropane trimethacrylate 19.8g. b) unsaturated polymer Synthesized as described below, 40 grams.

Same as Ex. 4.40 grams υ polyiso- TDI, 3 cyanate in mole equivalent il) polyol, in Olin 20-265, 1 mole equivalent iii) acrylate, Hydroxyethyl in mole acrylate, 4. equivalent iv) catalyst Dibutyltin dilaurate, 0.14% v) inhibitor Hydroquinone mono- methyl ether 0.07% vi) solvent in Pentoxone (93.7) % (Pentoxone is a Registered Trade Mark) hydroxylethyl acrylate 35% vi i) temp/time 40° to 45° for 2 hrs. °C/hr. then 20° to 85° for 4 vi ii) viscosity Thixotropic after 3 days 5042 4 ix) % Nonvolatiles actual theroeti cal 63.1 65 c) additive in gram Vinyl Silane A-172 2.0 grams Acrylic Acid 1.6 grams. Vinyl Silane EXAMPLE Wedron 5010 Port Crescent Free Radical Initiator (Part II) a) peroxide component (90%) t-butyl t-butyl peracetate hydroperoxide 2.2% (6 grams) b) catalytic component S02 gas Heat 450°F (232°C) for 90 Sec. Gas time, sec. 0.5 Purge time, sec. 15 with N2 Tensile Strength, psi out of box 53 (363 x 10 75 (514 χ ΙΟ0 N/m2) N/m2) 3 hr. 93 (637 χ 103 N/m2) hr. cold strength 155 (1062 x 103 N/m2) 160 (1096 x 103 N/m2) Binder level (Part I + peroxide component) 2% 2% 5 EXAMPLE 10 11 Sand Wedron 5010 Wedron 5010 PART I Same as Ex. 10 10 a) unsaturated momoner Acrylic acid 1.6 grams, trimethylolpropane triacrylate 9.9g. b) unsaturated polymer Synthesized as described below, 20 grams. 15 unsaturated polymer synthesis i) polyisocyanate mole equivalent TDI, 3.5 20 ii) polyol, in mole equivalent glycerine diethylene glycol mixture (1:1),1 iii) acrylate, in mole Hydroxyethyl equivalent acrylate 4.5 iv) catalyst dibutylti n dilaurate 0.14% 5 v) inhibitor hydroqui none monomethyl ether 0.07% 10 vi) solvent in % ethylhexyl acrylate + hydroxyethyl acrylate (4:6) 40% vii) temp/time °C/hr. 40 to 45° for 2 hrs then 80 to 85° for 4.8 hours. 15 viii) viscosity ix) % Nonvolatiles actual theoreti cal 10 stokes 59.9 60.0 20 c) additive in gram Free Radical Initiator (Part II) Vinyl silane A-172, 2 HiSol 10 10.7. 25 a) peroxide component 70% t-butyl hydroperoxide 2.2% b) catalytic component S02 gas 3/2% S02 gas in N2 carrier gas Gas time, sec.

Purge time, sec.

Tensile Strength, psi out of box hr. hr.

Binder level (Part I + peroxide component) Metal Cast Shakeout % EXAMPLE Sand PART I a) unsaturated monomer 0.5 1/2 15 with Ng gas None 228 (1562 χ 103 N/m2) 227 (1555 χ 103 N/m2) 257 (1760 χ 103 N/m2) 70 (479 χ 103 N/m2) 112 (836 χ 103 N/m2) 223 (1527 x 10 N/m2) 2« 1.5 Alumi num Wedron 5010 Acrylic acid 1.6g. diethylene glycol 5.49 trimethylol propane triacrylate 9.9 - 38 b) unsaturated polymer Synthesized as described below, 20 grams. unsaturated polymer synthesi s i) ii) polyisocyanate mole equivalents polyol, i n mole 4 glycerine 1 iii) equivalents acrylate, in mole hydroxyethyl acrylate 10 iv) equivalents catalyst dibutyltin dilaurate 0.14 v) i nhibitor hydroquinone monomethyl ether vi) solvent in % 0.03 methyl isoamyl ketone, HiSol 15 vii) temp/time °C/hr 10 (65:35) 35% 40 to 45° for 1.75 hours then ix) vixcosity, stokes 80 to 85° for 4.5 hours 10 20 x) % Nonvolatiles actual 64.1 theoreti cal 65 c) additive in grams Vinyl silane 2.0 HiSol 10 5.3 Free Radical Initiator (Part 25 II) • 50414 a) peroxide component b) catalytic component Gas time, sec.

Purge time, sec.

Tensile Strength, psi out of box hr. hr.

Binder level (Part I + peroxide component) Metal Cast Shakeout % EXAMPLE Sand PART I a) unsaturated monomer 22.2% t-butylhydroperoxide - 70 1% S02 gas in Ng carrier gas None 218 (1493 χ 103 N/m2) 157 (1075 x 103 N/m2) 233 (1596 χ 103 N/m2) 1.5 Alumi num 100 Wedron 5010 Acrylic acid 1.6g. diethylene glycol 5.49 trimethylol 0 414 - 40 propane triacrylate 9.9 b) unsaturated polymer Synthesized as described below, 20 grams. unsaturated polymer 5 synthesis i) polyi socyanate mole equivalents ii) polyol, in mole equivalents 10 iii) acrylate, in mole equivalents iv) catalyst v) inhibitor 15 vi) solvent in % vii) temp/time °C/hr viii) viscosity, stokes 20 ix) i Nonvolatiles actual theoreti cal c) additive in grams glycerine 1 hydroxyethyl acrylate dibutyltin dilaurate 0.14 hydroquinone monomethyl ether 0.03 methyl isoamyl ketone, HiSol 10 (65:35) 35% to 45° for 1.75 hours then 80 to 85° for 4.5 hours 10 64.1 Vinyl silane 2.0 Hi Sol 10 5.3 Free Radical Initiator (Part II) a) peroxide component 2.2% t-butylhydroperoxide - 70 b) catalytic component so2 gas Gas time, sec. 0.5 Purge time, sec. 15 with air Tensile Strength, psi out of box 3 hr. 24 hr. 177 (1212 x 103 N/m2) 95 (651 x 103 N/m2) 150 (1027 x 103 N/m2) Binder level (Part I + peroxide component) 1.5 Metal Cast Aluminum Shakeout % 100

Claims (21)

1. A process for forming shaped foundry articles compri si ng : a) distributing on a foundry aggregate a binding 5 amount of a binder material, said binder material comprising an ethylenically unsaturated monomer or polymer; b) shaping the aggregate into the desired foundry article, and 10 c) thereafter non-anaerobically polymerizing the binder material by means of a free radical initiator comprising an organic peroxide by application of heat and/or a catalytic agent.

2. The process of Claim 1, wherein the aggregate 15 is sand.

3. The process of Claim 1 or Claim 2, wherein the binder material comprises a mixture of at least two ethylenically unsaturated monomers.

4. The process of Claim 1 or Claim 2, wherein the 20 binder material comprises a mixture of at least two ethylenically unsaturated polymers.

5. The process of Claim 1 or Claim 2, wherein the - 43 binder material comprises at least one ethylenically unsaturated polymer and at least one ethylenically unsaturated monomer.

6. The process of any preceding Claim, wherein 5 gaseous sulphur dioxide is used as the catalytic agent.

7. The process of Claim 6, wherein the catalytic agent is suspended in a carrier gas and the binder material is exposed to it for at least 0.5 seconds.

8. The process of any one of Claims 1 to 5, wherein 10 in step (c) an elevated temperature of at least 125°F (52°C) is employed.

9. The process of any preceding Claim, wherein the amount of binder material is up to 10 per cent based upon the weight of the foundry aggregate. 15 10. The process of Claim 1 or Claim 2, wherein the binder material comprises an ethylenically unsaturated polymer which is an oligomer. 11. The process of Claim 1 or Claim 2, wherein the binder material comprises an ethylenically unsaturated 20 polymer which is an adduct. - 44 12. A process for binding at least two particulate materials in which the binder causes the particulate materials to cohere adequately for metal casting to take place in contact therewith but allows the materials to 5 separate readily enough thereafter for shake-out to be effected, which process comprises: a) distributing on at least one of said materials a binding amount of a binder material, said binder material comprising an ethylenically unsaturated monomer or

10. Polymer; b) bringing the materials to be bound together into contact, and c) thereafter non-anaerobically polymerizing the binder material by means of a free radical initiator 15 comprising an organic peroxide by application of heat and/or a catalytic agent.

11. 13. The process of Claim 12, wherein the binder material comprises a mixture of at least two ethylenically unsaturated monomers. 20

12. 14. The process of Claim 12, wherein the binder material comprises a mixture of at least two ethylenically unsaturated polymers.

13. 15. The process of Claim 12, wherein the binder material comprises at least on ethylenically unsaturated - 45 polymer and at least one ethylenically unsaturated monomer.

14. 16. The process of any one of Claims 12 to 15, wherein gaseous sulphur dioxide is used as the catalytic agent.

15. 17. The process of Claim 16, wherein the catalytic agent is suspended in a carrier gas and the binder material is exposed to it for at leat 0.5 seconds.

16. 18. The process of any one of Claims 12 to 15, wherein in step (c) an elevated temperature of at least 125°F (52°C) is employed.

17. 19. The process of Claim 12, wherein the binder material comprises an ethylenically unsaturated polymer which is an oligomer.

18. 20. The process of Claim 12, wherein the binder material comprises an ethylenically unsaturated polymer which is an adduct.

19. 21. Process of casting lightweight metal articles, said metal articles being shaped by use of foundry articles, which foundry articles collapse after casting said metal articles, comprising: S04S.4 - 46 a) forming a shaped foundry article as described in any one of Claims 1 to 11; b) heating a lightweight metal until it melts and is castable; 5 c) casting said lightweight metal using the shaped foundry article; d) allowing the cast metal to solidify; and e) collapsing the foundry article and removing said collapsed foundry article from the cast lightweight 10 metal article.

20. 22. A process substantially as hereinbefore described with reference to the Examples.

21. 23. Shaped foundry articles whenever prepared by a process as claimed in any of claims 1 to 21.