SE446098C - PROCEDURE FOR CASTING LIGHT METALS USING A URETANE BINDING AGENT - Google Patents

Description

Although the self-catalytic nature represents a marked advance, the invention is not limited to such. but in some embodiments a catalyst may also be incorporated.

According to the invention, another very essential feature is further provided. A long-known need in the casting industry has been a No-Bake and a Cold Box binder for the production of casting parts for light metals, such as aluminum and magnesium.

The prior art No-Bake and Cold Box binders could not provide cores and molds for casting these light metals, which at the same time exhibited the required core and shape properties. When sufficient binder was used to provide useful strength and abrasion resistance, the cores were broken. and the molds do not sink particularly well at the casting temperatures of light metals. the poor shaking properties. . __., .._, ... M as good shaking properties.

In other words, an existing problem has been to find a binder which, on the one hand, gave strong, non-crumbly cores and molds and, on the other hand, decomposed well at the casting temperature of aluminum and magnesium to thereby give a simple shaking.

An object of the present invention is to provide a casting binder composition using a polyol and a polyisocyanate in admixture, the polyol being an amine polyol.

The mixture can be cured with a gaseous catalyst. The amine polyols of the present invention are normally obtained as the reaction product of an amine and an alkylene oxide.

Another object of the invention is to provide No-Bake and Cold Box urethane binder compositions. Yet another object of the present invention is to provide No-Bake and Cold Box urethane binders which can be used to provide cores and molds with good strength and non-crumbability but which still degrade well at low casting temperatures, i.e. below the casting temperatures for ferrous metals. The cores and molds of the present invention exhibit the combination of good strength and good shaking properties at the casting temperatures of light metals, such as aluminum and magnesium. In particular, the present invention offers great advantages in connection with the casting of hollow lightweight or light metal moldings thanks to the excellent shaking properties of the new binder component. sition has been shown to possess.

It has been found that a urethane binder formed as the reaction product of a polymeric isocyanate and an amine-based polyol can be used to make cores and molds. The binder can be cured rapidly using a gaseous tertiary amine catalyst. It has been found that a polyol which is the reaction product of an amine compound and an alkylene oxide can be combined with a polymeric isocyanate to form a No-Bake or a Cold Box binder which, when mixed with sand or other suitable cast ballast materials and cures, forms cores and molds, which exhibit excellent working properties, i.e. strength, abrasion resistance and non-brittleness. These properties are coupled with excellent shaking properties when used for casting non-ferrous metals. This combination of good working properties and excellent shaking properties is especially significant and unique, when the binder is used for the production of cores intended for use in low-temperature casting and entails significant advantages in casting hollow parts. A catalyst can be used to cure the components of the binder system. Suitable catalysts for the Cold Box aspect of the invention are gaseous tertiary amines or vapors which can be introduced in vapor form. Trimethylamine, dimethylethylamine and triethylamine are preferred catalysts. A catalyst is not necessarily a component of the No-Bake binder system. However, suitable catalysts can also be used in the No-Bake binder aspect of the invention, and such catalysts are preferred along with certain amine polyols, when rapid curing is required.

The resin compositions of the present invention are useful as two-component compositions or systems. The first component is the amine polyol, and the second component is the polyisocyanate. Both components are in liquid form and are generally solutions with organic solvents.

At the time of use, ie. when the urethane binder is formed, the amine polyol moiety and the polyisocyanate moiety are combined, whereupon the mixture is used for the intended application. In casting applications, ie. When using the compositions as binders for cores and molds, it is convenient to first mix a component or part with a casting ballast material, such as sand. Thereafter, the second component is added, and when even distribution of the binder on the aggregate material has been obtained, the resilient casting mixture is formed or imparted to the desired shape. The shaped product can be immediately set aside and hardens to form a core or mold at room temperature. The compositions of the present invention are generally self-catalytic to some extent. This means that, once the amine polyol and the isocyanate have been combined, the reactivity of the polyol relative to the isocyanate is such that the reaction proceeds rapidly enough that a catalyst is not required.

The degree of reactivity of the amine polyol and the polyisocyanate depends on the reactivity of the polyol. The shaped product can also be cured to form a core or mold by contacting the mold body with a gaseous catalyst.

Despite the fact that the compositions are self-catalytic, liquid amine catalysts and metallic catalysts, which are known in the urethane technology, can be used in the No Bake version.

It should be noted that in some cases the use of a catalyst with the amine polyol and polyisocyanate components is favorable and preferred. By selecting the appropriate catalyst, the conditions of the nucleation process, e.g. working hours and peeling time, are regulated in the desired way. In commercial application, it may be necessary to use a catalyst for certain polyols in order to achieve desired production rates.

Gaseous amine catalysts, which are known in Cold Box technology, can also be used. The actual curing step can be accomplished by suspending a tertiary amine in a stream of inert gas and passing the flow stream containing the tertiary amine, under sufficient pressure to penetrate the molded part, through the mold until the resin has cured. The binder compositions of the present invention require extremely short curing times to obtain acceptable tensile strength, which is a particularly valuable contribution to the art in the field from a commercial point of view. times are easily determined experimentally.

Optimal Curing Since only catalytic concentrations of the tertiary amine are required to effect curing, a very dilute current is usually sufficient to effect curing. However, concentrations of the tertiary amine in excess of the concentration necessary to effect curing are not detrimental to the finished cured product. Inert gas streams, e.g. air, carbon dioxide or nitrogen, containing from 0.01 to 20% by volume of tertiary amine can be used. Normally, gaseous tertiary amines can be passed through the mold as such or in dilute form. Suitable tertiary amines are gaseous tertiary amines, such as trimethylamine. However, normally liquid tertiary amines, such as triethylamine, are equally suitable in volatile form or if they are suspended in a gaseous medium and then passed through the mold. Although ammonia, primary amines and secondary amines show some activity in achieving a room temperature reaction, they are clearly inferior to the tertiary amines. Functionally, substituted amines, such as dimethylethanolamine, are included within the scope of tertiary amines, and such can also be used as hardeners. Functional groups which do not interfere with the effect of the tertiary amine are hydroxyl groups, alkoxy groups, amino and alkylamino groups, ketoxy groups, thio groups and the like.

The amine polyols used to form the urethane binder compositions of the present invention are normally prepared as the reaction product of an alkylene oxide and an amine compound. When the term "amine polyol" is used in the present case, it is intended to identify such reaction products, but is not specifically limited to such synthetic agents. In general, any polyol containing at least one or more tertiary amino groups is considered to be within the definition of "amine polyol". The alkylene oxides used to prepare the amine polyols are preferably ethylene oxide and propylene oxide.

However, it should be possible to use other alkylene oxides as well. The amount of alkylene oxide in moles per mole of amine compound can vary considerably. It can be assumed that the degree of alkoxylation does not reduce the ability of the resulting amine polyol to act as a binder.

Among useful amine compounds for reaction with alkylene oxides to form the amine polyols useful in the binder composition of the present invention are ammonia and mono- and polyamino compounds having primary and secondary amino nitrogen atoms. Concrete examples of this are aliphatic amines, such as primary alkylamines, ethylenediamine, diethylenetri trivalent and the agent is then said to be "dead". 7905016-7 amine and triethylenetetramine, cycloaliphatic amines, aromatic amines such as ortho-, meta- and para-phenylenediamines, aniline-formaldehyde resins and the like. the amine polyols can also be used.

Mixtures of the above In addition, a mixture of amine polyols with other polyols, i.e. non-amine polyols, useful. It is generally believed that amine-containing compounds which, when alkoxylated, yield a polyol having two or more reactive hydroxyl groups, are useful in the compositions of the present invention.

The nature of the polyol component used affects the conditions for the core production process. In a Cold Box process, ie. a process in which the resin-coated sand is cured by gassing with an amine catalyst is an important property of the binder in its shelf life or shelf life. The service life of the bench, which corresponds to the service life of a No-Bake system, is the period of time during which resin-coated sand can be used. Once a binder has been distributed on a ballast material, the binder begins to react.

After a certain time, the reaction has gone so far that the resin-coated sand can no longer be used. The sand coated with binder- Once the sand has been coated with resin, the period of time that elapses before the sand mixture is "dead" is known as the bench life in a Cold Box system. It has been found that the use of aromatic initiated amine polyols results in a surprising prolongation of the bench life of the resin coated sand. This surprising result is of great usefulness and is considered to be very significant.

As discussed above, it has been found that mixing an amine polyol with another polyol, a polyhydroxyl compound capable of reacting with a polyisocyanate, can be utilized. This usefulness is particularly evident with regard to the strengths outside said box which are obtained after the binder has been exposed to the catalyst. Particularly preferred are hydroxy-containing phenolic resins described in U.S. Pat. No. 3,885,797 and known in the foundry industry as PEP resins.

The second component or package of the new binder composition comprises an aliphatic, cycloaliphatic or aromatic polyisocyanate having preferably from 2 to 5 isocyanate groups. If desired, mixtures of polyisocyanates can be used. Isocyanate prepolymers formed by reaction between excess polyisocyanate and polyhydric alcohol, e.g. a prepolymer of toluene diisocyanate and ethylene glycol, can also be used. Suitable polyisocyanates include the aliphatic polyisocyanates, such as hexamethylene diisocyanate, alicyclic polyisocyanates, such as 4, β'-dicyclohexylmethane diisocyanates, and aromatic polyisocyanates, such as 2, fl- and 2,6-toluene diisocyanate and diphenyl diphenyl. Further examples of suitable polyisocyanates are 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate, xylylene diisocyanate and the methyl derivatives thereof, polymethylene polyphenyl isocyanates and the methyl derivatives thereof, chlorophenylene-2, N-diisocyanate and the like. Although all polyisocyanates react with the amine polyol to form a crosslinked polymer structure, the preferred polyisocyanates are aromatic polyisocyanates and especially diphenylmethane diisocyanate, triphenylmethane triisocyanate and mixtures thereof.

The polyisocyanate is usually used in an approximately stoichiometric amount, i.e. in sufficient concentration to cause curing of the amine polyol. However, it is possible to deviate from this amount within certain limits, and in some cases benefits may be obtained thereby. Generally, the polyisocyanate is used in the range of from 10 to 500% by weight, based on the weight of the amine polyol. Preferably from 20 to 300% by weight of polyisocyanate, calculated on the same basis, is used. The polyisocyanate was used in liquid form.

Liquid polyisocyanates can be used in undiluted form. Solid or viscous polyisocyanates are used in the form of solutions with organic solvents, the solvent being present in an amount of up to 80% by weight of the solution. Although the solvent used in combination with either the amine polyol or the polyisocyanate or for both components does not significantly participate in the reaction between the isocyanate and the amine polyol, it can affect the reaction. Thus, the difference in polarity between the polyisocyanate and the amine polyol limits the choice of solvent in which both components are miscible. Such miscibility or compatibility is necessary to achieve complete reaction and curing of the adhesive compositions of the present invention.

Polar solvents of either the protic or aprotic type are good solvents for the amine polyol. It is therefore convenient to use solvents or combinations of solvents where the solvent or solvents for the polyol and for the polyisocyanate when mixed are compatible with each other. In addition to miscibility, the solvents of either the polyol or the polyisocyanate are selected to give low viscosity, low odor, high boiling point and inertness. Examples of such solvents are benzene, toluene, xylene, ethylbenzene and mixtures thereof. Preferred aromatic solvents are solvents and mixtures thereof which have a high aromatic content and a boiling point in the range from 138 ° C to 385 ° C. The polar solvents should not be extremely polar so that they become incompatible when used in combination with the aromatic solvent. Suitable polar solvents are generally those which in this art have been classified as coupling solvents; and examples thereof may be furfural, Cellosolve, glycol diacetate, butyl Cellosolve acetate, isophorone and the like. It is also possible to use certain reactive polyols as solvents. In addition, it may be added that water has been found to be a suitable solvent for the amine polyol under certain conditions.

The binder components are combined and then mixed with sand or a similar casting ballast material to form the casting mixture, or the casting mixture can be formed by successively mixing the components with the ballast material. Methods for distributing the binder on the ballast particles are well known to those skilled in the art. The casting mixture may optionally contain other constituents, such as iron oxide, ground flax fibers, wood cereals, pitch, refractory flour and the like. The ballast material, e.g. sand, is usually the main constituent and the binder part constitutes a relatively small amount. Although the sand used preferably consists of dry sand, a certain moisture can be tolerated. This is especially true if the solvent used is immiscible with water or if an excess of the polyisocyanate required for curing is used, since such an excess of polyisocyanate reacts with the water and water is a useful solvent for the amine polyol.

As previously stated, the excellent shaking ability or ability to "collapse" for cores made using the binder of the present invention can be considered a significant discovery. The adhesives of the present invention are readily degraded, allowing separation of the core from the cast metal. For casting at low temperature, e.g. 980 ° C or below, shaking has been a major problem. Typically, non-ferrous metals including aluminum and magnesium are cast at these temperatures. If the adhesive does not "break down", this means great difficulties in removing the sand from the casting. Thus, cores requiring a low degree of shaking ability or ability to collapse, i.e. a low degree of adhesive degradation, require longer time and energy to remove The use of the binder compositions of the present invention results in many cases in virtually 100% shaking without the need for any external energy.The improvement in shaking ability can be attributed to the presence of the amine polyol in the binder composition. in the field, the ability to shake out a core depends to some extent on the amount of binder used to bind the sand particles into a coherent form. The percentage of binder used, based on the weight of the sand, depends on the desired core properties that are expected. As will be readily appreciated, when the amount of binder l in the system increases, an increase in the tensile strength of the core usually occurs. Accordingly, the level of binder can be varied within reasonable limits to obtain -A preferred range of the binder according to the present invention is from 0.7 $ to 2.55 based on the weight of the sand. However, it may be possible to use as little as 0.51 and as much as 10% binder and still achieve properties that are advantageous in certain applications. However, it has also been noted that, as the binder level increases, the degree of shaking may decrease at the higher binder levels.

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

EXAMPLE 1 An amine polyol was prepared by propoxylating 1.0 mole of ethylenediamine with R, 2 moles of propylene oxide. A solution with a solids content of 40% of the amine polyol was prepared by dissolving the polyol in an aromatic solvent, which is commercially available under the trademark BISOLCB 10. the desired properties.

This solution is mentioned in Part I. A polymeric isocyanate solution, 75% solids content, based on Mondur MR, which is commercially available from Mobay, was prepared using an aromatic solvent, also in this case HISOLQ§ 10. part II.

Wedron 5010 sand (washed and dried, fine-grained silica sand, AFSGFN 66) was placed in a suitable mixer. Part I was mixed with the sand until a homogeneous coating was obtained. Part II was added to the coated sand and mixed until a homogeneous sand mixture was obtained. An almost stoichiometric amount of polyisocyanate, a small excess, was used to effect complete reaction with the hydroxyl groups in the polyol. 1 l / 2% by weight of sand was used based on the total binder (equal amounts of parts I and II).

The mixture of sand, polyol and polyisocyanate was placed in a core box, and standardized tensile briquettes known as "dog bones" were prepared. A pot life of 5 1/2 minutes and a molding time of 8 minutes were obtained. The tensile strength values after 2 hours, U hours and 2N hours, respectively. were 21, 26 and 27 kg / cm 2, respectively.

The "dog bone" cores were used in shaking studies with aluminum castings. Seven tensile briquettes (dog bones) were arranged in one mold. The mold contained a gate system. The shape is such that it gives hollow castings with a metal thickness of about 6.3 mm on all sides. An opening at one end of the casting member is provided for removing the core from the casting member. Molten aluminum with a temperature of about 70,000 made from aluminum raw material was poured into the mold.

The isocyanate solution is called After cooling for about 1 hour, the aluminum casting parts were taken out through the gate system and removed from the mold for shaking attempts.

The shaking tests are performed in such a way that a casting part is placed in a 3.8 liter container. The container is placed on a shaking mechanism and subjected to shaking for two minutes.

The weight of the sand core removed from the casting part in this way is compared with the original weight of the sand core, and the percentage elimination is calculated. Remaining sand in the casting part after the shaking described above is removed, by scraping and also weighed. The sand core bonded with the above-described amine polyol polyisxwanate binder collapsed and flowed out of the aluminum casting part without the need for the shaking mechanism and without any external mechanical energy having to be applied.

EXAMPLES 2-6 Using the procedures described in Example 1, test nuclei were prepared in the form of dog bones using the 100% shake. components and the methods set out and described below.

The cores were used in shaking experiments using aluminum casting parts as described in Example 1.

Sand Amine compound Alkylene oxide (AO) Molar ratio AO: amine Amine polyol Polyisocyanate Solvent in amine polyol Solvent in polyisocyanate Catalyst Pot life Milling time Percent binder Example 2 Example Example U Examplezš Example 6 Wedron Wedron Wedron Wedron Wedron 5010 5010 S010 5010 5010 Diethylene- Triethylene- Ethylene- triamine tetramine diamine Prgpylene- Propylene- Propylene oxide oxide oxide 5.1: l 6.2: l 12: 1 Triecanol- QuADRoLb amin fgån UPJOHN Mondur MR Mondur MR Mondur MR Mondur MR Mondur MR N01 10% 60% 60% 601 HISOL 10 ISOFORON ISOFORON HISOL 10 HISOL 10 None None 251 25% 251 HISOL 10 HISOL 10 HISOL 10 None None None None None 5 min. 2 min. 0.5 min. 6 min. 5 minutes. 12 min. N, 5 min. 1.0 min. 9 min. 8 min.

H05 Part I 50% Part I 60% Part I 50% Part I 50% Part I 60% Part II 50% Part II H01 Part II 501 Part II 501 Part II 10 15 20 25 30 35 7905016-7 12 Example 2 Example 3 Example N Example 5 Example 6 Tensile strength in kg / cm2 z hours. 1.0 10.7 6.0 25.2 25.1 u tim. 8.3 111.7 7.9 25.6 211.5 '21: tim. 11.1 »17.3 - 16.1 26.8 utskakning 1ooz iooz mo; 1oo: mo; Kernels manufactured in the manner described above were found to collapse and run out of the casting part without any shaking mechanism having to be used and without application of any external mechanical energy. aUPJOHN is a trademark for triethanolamine, ie. ethoxylated ammonia, which is commercially available from Apjohn Corp.

DQUADROL is the trademark for propoxylated ethylenediamine, molar ratio üzl, commercially available from BASF Hyandotte.

EXAMPLE 7 An aromatic amine polyol is prepared by propoxylating one mole of meta-phenylenediamine with N, 2 moles of propylene oxide. A solution with a solids content of NO1 of the aromatic amine polyol was prepared by dissolving the polyol in an aliphatic solvent, butyl Cellosolve. This solution is called Part I. A polymeric isocyanate solution, solids content 751, based on Mondur MR, commercially available from Mobay, was prepared using an aromatic solvent, which is commercially available as HISOL®10. The isocyanate solution is called Part II.

An almost stoichiometric amount of polyisocyanate for complete reaction with the hydroxyl groups in the polyol was used. wedron 5010 sand (washed and dried, fine-grained silica sand, AFSGFN 66) was placed in a suitable mixer. Part I was mixed with the sand until a homogeneous coating was obtained. Incorporated in Part I was a urethane catalyst, namely triethylenediamine, which is commercially available under the DABCO brand. This catalyst is a well known urethane catalyst.

Based on the weight of Part I, 0.8 was used! catalyst. Part II was added to the coated sand and mixed with it until a homogeneous sand mixture was obtained. l l / 2 weight! sand was used, calculated on the total binder (Part I and Part II).

The mixture of sand, polyol, catalyst and polyisocyanate was placed in a core box, and standardized tensile strength briquettes, known as "dog bones", were prepared. . A service life of 70 minutes and a molding time of 110 minutes were obtained. the tensile strength after Zü hours was 16.1 kg / cm 2.

The "dog bone" cores were used in shaking studies with alu- Seven tensile strength briquettes (dog bones) an- The mold contained a gate system. The shape is Dragminium casting details. arranged in a form. such that it provides hollow castings with a metal thickness of about 6.4 mm on all sides. An opening at one end of the casting member is provided for removing the core from the casting member. Molten aluminum with a temperature of about 700 ° C made from aluminum blanks was poured into the mold. After cooling for about 1 hour, the aluminum casting parts were taken out through the gate system and removed from the mold for shaking attempts.

The shaking tests are performed in such a way that a casting part is placed in a 3.8 liter container. The container is placed on a shaking mechanism and subjected to shaking for two minutes.

The weight of the sand core removed from the casting part in this way is compared with the original weight of the sand core, and the percentage elimination is calculated. The remaining sand in the casting part after the shaking described above is removed by the described amine polyol-polyisocyanate catalyst binder collapsed and amber from the aluminum casting part without the shaking mechanism having to be used and without any external mechanical energy having to be applied. The shake-out was $ 100.

EXAMPLES 8-1 Using the procedures described in Example 7, test cores in the form of dog bones were prepared using the components and methods described below. The cores were used in the shake test using aluminum casting parts as described in Example 7. Example 8 Example 9 Example 10 Example 11 Sand Wedron Wedron Wedron Wedron J 5010 5010 5010 5010 Amine Compound Alkylene oxide Molar ratio A0-amine Amine- Pluracolc Pluracolc Pluracold Pluracold P ° 1 ¥ 0l 757 757 795 795 Polyiso- Mondur MB Mondur MR Mondur MR Mondur MR cyanate Solution- N01 351 351 351 agent 1 HISOL 10 Water HISOL 10 HISOL 10 aminep 10 aminep ol Lßsnings- uuze Inge: ssze 3sz ° average 1 polyisocyanab Catalyst (l) l, N1 None None (1) 1 1/21 Application time 25 min. 10 min. 11.5 min. 7 min. ÅVf0Pm- 31 min. 16 min. 16 min. 10.5 min. Percentage 1.51 1.71 1.51 1.51 binders 501 Part I 601 Part I 501 Part I 501 Part I 501 Part II H01 Part II 501 Part II 501 Part II Tensile strength in kg / cmz 2 hrs. 15.8 7.6 1U, 2 15.6 (3 hrs.) H hrs. - 9.0 (3 hrs.) LN, 9 14.7 2D hrs. 25.8 - 22.6 22, N Shake-out 921 1001 100% Cores made as described above were found to collapse and run out of the casting part without the need for any shaking mechanism and without the need for any external mechanical energy. (1) 501 of phenylpropylpyridine and 501 of a lithium salt of a carboxylic acid. C) Pluracol 767 is a trademark for a propoxylated aromatic amine-based polyol commercially available from BASF wyandotte. d) Pluracol 795 is a trademark for an ethoxylated aromatic amine-based polyol commercially available from BASF Wyandotte. . e) a mixture of HISOL 10 and the kerosene.

EXAMPLE 12 An aromatic amine polyol was prepared by propoxylating one mole of orthophenylenediamine with ü2 moles of propylene oxide. A solution with a solids content of NO! of the aromatic amine polyol was prepared by dissolving the polyol in isophorone. This solution is called Part I. A polymeric isocyanate, Mondur MR, is called Part II. An almost stoichiometric length of polyisocyanate for complete reaction with the hydroxyl groups in the polyol was used.

Wedron 5010 sand (washed and dried, fine-grained silica sand, AFSGFN 66) was placed in a suitable mixer. Part I was mixed in the sand until a homogeneous coating was obtained.

Part I incorporated a 33% solution in dipropylene glycol of a urethane catalyst, triethylenediamine, commercially available under the trademark DABCO. This catalyst is a well-known urethane catalyst. Based on the weight of Part I, 1.01 catalyst was used.

Part II was added to the coated sand and mixed with it until a homogeneous sand mixture was obtained. l l / 2 weight! sand was used calculated on the total binder ($ 55 of Part I and H5! of Part II).

The mixture of sand, polyol, catalyst and polyisocyanate was placed in a core box, and standardized tensile briquettes, known as "dog bones", were prepared. A service life of 9 min. and a demolding time of 20 minutes was obtained. Tensile strength in kg / cm2 after 2 hours resp. 2U hours were 20, H resp. 21.9.

The "dog bone" cores were used in shaking studies with alu- Seven tensile strength briquettes (dog bone) an- The mold contained a gate system. The shape is minimum casting details. arranged in a form. such that it gives hollow castings with a metal thickness_of about 6, N mm on all sides. An opening at one end of the casting member 10 is provided for removing the core from the casting member. Molten aluminum with a temperature of about 700 ° C made from aluminum blanks was poured into the mold. After cooling for about 1 hour, the aluminum casting parts were taken out through the gate system and removed from the mold for shaking attempts.

The shaking tests are performed in such a way that a casting part is placed in a 3.8 liter container. The container is placed on a shaking mechanism and subjected to shaking for two minutes.

The weight of the sand core removed from the casting part in this way is compared with the original weight of the sand core, and the percentage elimination is calculated. The remaining sand in the casting part after the shaking described above is removed by the described amine polyol-polyisocyanate catalyst binder collapsed and roughened out of the aluminum casting part without the shaking mechanism having to be used and without any external mechanical energy having to be applied. The shaking was 100%.

EXAMPLES 13-15 Using the procedures described in Example 12, test nuclei were prepared in the form of dog bones using the components and methods described below. The cores were used in shake tests using aluminum casting parts as described in Example 12.

Example 13 Example 14 Example 15 Sand Wedron Wedron Wedron 5010 5010 5010 Amine- _ Mecaiphenylene Sum / Anal 'Anne compound diamine an anile-formaldehyde resin from Upjohn Alkylene- Propylene- Propylene- Propylene oxide oxide oxide Mol- 4.2 : l N, 2: l 2.2: l holding A0; amine Amine polyol 'Polyiso- Mondur MR Mondur MR Mondur MR cyanate Solution 60% ISOFORON 60% ISOFORON 60% (X) agent 1 amine polyol 10 15 20 25 30 35 U 7905016-7 Solution None None None agent in polyisocyanate Catalyst None None 1! Dabco Operating time H5 min. 70 min. 70 min.

Deform- 78 min. 101 min. lH0 min. percentage 1.55 1.5; 1.5; binder 55% ne1 1 73: Part I 61: Part 1 N51 Part II 271 Part II 391 Part II Tensile strength in kg / cm2 2 hrs. lo, 2 1.6 N tim. 21.5 20 tim. 22, U 9.8 12.6 Shake 891 1001 731 (X) a mixture of butyl Cellosolve acetate (H0 $) and HISOL 10 (20%) Kernels prepared as described above were found to collapse and flow or run out of the casting part during use 'of a shaking mechanism and with application of external mechanical energy.

EXAMPLE 16 An amine polyol was prepared by propoxylating 1.0 mole of meta-phenylenediamine with 6.0 moles of propylene oxide. A solution with a solids content of NO1 of the amine polyol was prepared by dissolving the polyol in a mixture of solvent with 40% isophorone, 16.51 of an aromatic solvent and 3.52 kerosene.

This solution is called Part I. A polymeric isocyanate solution, solids content 751, based on Mondur MR, commercially available from Mobay, was prepared using an aromatic solvent, HISOL (® 10. The isocyanate solution is called Part II).

An almost stoichiometric amount of polyisocyanate for complete reaction with the hydroxyl groups of the polyol was used.

Wedron 5010 sand (washed and dried fine-grained silica sand, AFSGFN 66) was placed in a suitable mixer.

Part I was mixed with the sand until a homogeneous coating was obtained. Part II was added to the coated sand and mixed 10 15 20 ZS 30 35% percent shake is calculated. .79Û5Û16'7 N with this until a homogeneous sand mixture is obtained. 1 1/2 weight! sand was used based on the total binder (equal amounts of Part I and Part II).

The mixture of sand, polyol and polyisocyanate was blown into a conventional core cavity or box to produce standardized tensile strength briquettes, namely test cores in the form of so-called "dogbone". The dog bone-shaped test cores were cured by exposing the cores to a tertiary amine catalyst.

The amine catalyst, namely dimethylethylamine, was suspended in carbon dioxide, which acts as an inert bar gas. the cores were exposed to the amine catalyst for about 20 seconds (gas time) and allowed to remain in the core box for 10 minutes (residence time) before the core was removed from the box. The tensile strength values in kglcm2 were 1.8 outside the box, 5.0 after 1 hour and 9.5 after ZN hours.

"Dog bones": the beads were used in shaking studies with aluminum casting details. Seven tensile briquettes (dog bones) were arranged in a mold. The mold contained a gate system. An opening at one end of the casting member is provided for removing the core from the casting die. Molten aluminum now having a temperature of about 700 ° C made of aluminum blank is poured into the mold. After cooling for about 1 hour, the aluminum casting members were removed through the gate system and removed from the mold. for shaking attempts.

The shaking tests are performed in such a way that a casting part is placed in a 3.8 liter container. The container is placed on a shaking mechanism and subjected to shaking for two minutes.

The weight of the sand core removed from the casting part in this way is compared with the original weight of the sand core, and the remaining sand in the casting part after the shaking described above is removed by the described amine polyol-polyisocyanate binder collapsed and flowed out of the aluminum casting part. be used and without any external mechanical energy having to be applied. The shaking was 100%.

EXAMPLES 17-21 Using the procedures described in Example 16, test cores were prepared and tested using the following components and methods. 10 15 20 25 30 35 H0 45 7905016-'7 19 Exemp. 17 Exemp. 18 Exemp. 19 Exemp. 20 Exemp. 21 Sand Wedron Wedron Wedron Wedron Wedron 5010 5010 5010 5010 5010 Amine compound Aniline Ortho- Meta- Meta- CURITHANE phenylene phenylene phenylene- 103, a diamine aniline- formaldehyde resin marketed by Upjohn Alkylene- Propylene- Propylene- Propylene- Propylene- Propylene- oxide oxide oxide oxide oxide oxide oxide Mol- 2: 1 N, 2: 1 N, 2: 1 8: 1 4: 1 holding A0: amine Amine- polyol “Polyiso- Mondur MR Mondur MR Mondur MR Mondur Mm Mondur MR cyanate Solution - agent in 601 (1) 601 60% 601 (1) 60% amine polyol isophorone isophorone isophorone Solvent in None 25% (2) 25% 25% (2) No polyiso- HISOL 10 cyanate Cataly-Trimethyl 'Dimethyl- Dimethyl - Dimethyl- Trimethylsator amine ethylamine ethylamine ethylamine amine suspending-suspending-suspending row in CO row in CO row in CO 2 2 2 Gas time 10 sec. 10 sec. 10 sec. 20 sec. 5 sec.

Uppe- 5 min. 3 min. 10 min. 10 min. 2 min. holding time Tensile strength in kg / cm? when withdrawing from the box 2.1 3.5 0.0?, H 2.1 lthme LO N, 7A ZN tim. 6.3 6.0 7, 3.5 Total binder 1.5% 1.51 1.51 1.51 1.51 Part I 75% Part I 50% Part I 501 Part I 501 Part O 75% Part II 25% Part II 50% Part II 50% Part II 50! Part II 251 Uçskak- nlng 100% 100% 1001 100: 100; Cores prepared in the manner described above were found to collapse and run out of the casting part without the need for any shaking mechanism and without the need for any external mechanical energy. (l) A mixture of isophorone (ROI), aromatic solvents ($ 16.5), kerosene (}, 5¶) - (2) A mixture of an aromatic solvent marketed as Texaco Solvent 75U5 (191) and KGPOSGD (51 EXAMPLE 22 An amine polyol was prepared by propoxylating 1.0 mole of meta-phenylenediamine with 8.0 moles of propylene oxide. A phenolic polyol, which is commercially available as a PEP resin, was added to the amine polyol to prepare a polyol blend. The ratio of o-amine polyol to non-amine polyol was 2: 1. A solution with a solids content of 60! of the polyol mixture was prepared by dissolving the polyol mixture in isophorone solvent.

This solution is called Part I. A polymeric isocyanate solution, solids content 75%, based on Mondur MR, commercially available from Mobay, was prepared using a solvent mixture consisting of 192 Texaco YSNS, an aromatic solvent and 6% kerosene. The isocyanate solution is called Part II. A substantially stoichiometric amount of the polyisocyanate for complete reaction with the hydroxyl groups of the polyol was used. wedron 5010 sand (washed and dried fine-grained sand, AFSGN 66) was placed in a suitable mixer. Part I was mixed with the sand until a homogeneous coating was obtained. Part II was added to the coated sand and mixed with it until a homogeneous sand mixture was obtained. 1 l / 2 w / w sand was used on the total binder (NNZ of Part I and 565 of Part II). The mixture of sand, polyol and polyisocyanate was blown into a conventional core cavity or box to produce standardized tensile test cores known as "dog bones". The dog bone test cores were cured by being exposed to a catalyst in the form of a tertiary amine. The amine catalyst, dimethylethylamine, was suspended in carbon dioxide, which acts as an inert carrier gas. The cores were exposed to the amine catalyst for about 5 seconds (gas time) and held in the core box for 1 minute (residence time), before the core was removed from the box. The tensile strength values in kg / cm2 were U, l immediately after the core had been removed from the box, lN, 0 after 1 hour and lN, 7 at the time of casting.

LI- ll) 15 in 25 30 35 H0 21 79Û5Û16-7 The "dog bone" cores were used in shaking studies with aluminum casting details. Seven tensile briquettes (dog bone) were arranged in a mold. The mold contained a gate system. The mold is such that it gives hollow castings with a metal thickness of approx. 6, U mm on all sides An opening at one end of the casting part is provided to remove the core from the casting part.Melted aluminum with a temperature of about 700 ° C made of aluminum raw material was poured into the mold. cooling for about 1 hour, the aluminum casting parts were taken out through the gate system and removed from the mold for shaking attempts.

The shaking tests are performed in such a way that a casting part is placed in a 3.8 liter container. The container is placed on a shaking mechanism and subjected to shaking for two minutes.

The weight of the sand core removed from the casting part in this way is compared with the original weight of the sand core, and the percentage elimination is calculated. Remaining sand in the casting part after the shaking described above is removed by the described amine polyol polyisocyanate binder collapsed and flowed out of the aluminum casting part without the shaking mechanism having to be used and without any external mechanical energy having to be applied. The dropout rate was 1001.

EXAMPLE 23 and Zü sand Hedron 5010 WGGPOH 5010 Amine compound Curithane 105 Alkylene oxide Propylene oxide Molar ratio Alkylene oxide: amine ----- Amine polyol Pluracol 7351 Non-amine polyol Ratio amine polyolz Phenolic polyol Polyolicene polyol 2 Moleicolic polyol - N05 butyl-Cellosolve- N01 butyl-Cello- mixture acetate solve-acetate Solvent in polyiso- 25% aromatic solvent- 25% kerosene cyanating agent 7545, 65 kerosene Catalyst Trimethylamine Trimethylamine Gas time 5 sec. 5 sec.

Residence time l min. l min. 10 15 20 25 30 55 7905016-7 22 Dragnåiirastnet i ug / cmz 3,2 3.2 2 8,9 L1 hr.) 8,9 (1 hr.) 7,7 (u hr.) Ll, 3 (casting time) 8 .9 (casting time) Total binder ll / 21 1 l / 2% Part I NOW! Part I 501 Part II S51 Part II S01 Shaking 100% N81 1An amine-based polyol from BASF (assumed to be ethoxylated and aromatic).

The sand core bound with the amine polyol derived from propoxylation of Curithane 103, an aniline-formaldehyde resin marketed by Upjohn, collapsed and leaked out of the aluminum casting part without the need for any agitation mechanism and without the application of external energy. The sand core based on Pluracol 135 was shaken to obtain the specified degree of shaking.

Example 25 An amine polyol was prepared by propoxylating 1.0 mole of ethylenediamine with 8.0 moles of propylene oxide. A solution having a solids content of 50% of the amine polyol was prepared by dissolving the polyol in a mixture of solvents with 301 isophorone, 16.5% of an aromatic solvent and 3.51 kerosene. This solution is called Part I. A polymeric isocyanate solution, solids content 755, based on Mondur MR, commercially available from Mobay, was prepared using an aromatic solvent, Texaco 75N5 (191) and kerosene (61). The isocyanate solution is called Part II. An almost stoichiometric amount of polyisocyanate for complete reaction with the hydroxyl groups in the polyol was used.

Wedron 5010 sand (washed and dried fine-grained silica sand, AFSGFN 66) was placed in a suitable mixer. Part I was mixed with the sand until a homogeneous coating was obtained. Part II was added to the coated sand and mixed with it until a homogeneous sand mixture was obtained. One and a half weights! sand was used based on the total binder (equal amounts of Part I and Part II).

The mixture of sand, polyol and polyisocyanate was blown into a conventional core cavity or box to produce standardized test cores known as "dog bones" and g for tensile strength measurements. The dog bone test nuclei were cured by being exposed to a catalyst in the form of a tertiary amine, namely unmethylamine. The cores were exposed to the amine catalyst for about 10 seconds (gas time) and held in the core box for 5 minutes (residence time) before the core was removed from the box. The tensile strength in kg / cm2 was 5.6 15 minutes after gassing and 9.5 after 2ü hours.

The "uundhcn" cores were used in shaking studies with alu- Seven tensile briquettes (dog bones) an- The mold contained a gate system. The shape is such that it gives hollow castings with a metal thickness of about 6.ü mm on all sides. minium casting details. arranged in a form.

An opening at one end of the casting member is provided for removing the core from the casting member. Molten aluminum with a temperature of about 700 ° C made from aluminum blanks was poured into the mold. After cooling for about 1 hour, the aluminum casting parts were taken out through the gate system and removed from the mold for shaking attempts. In the shaking experiments are carried out in such a way that a casting detail is placed in a 3.8 liter container. The container is placed on a shaking mechanism and subjected to shaking for two minutes.

The weight of the sand core removed from the casting part in this way is compared with the original weight of the sand core, and the percentage elimination is calculated. The remaining sand in the casting part after the shaking described above is removed by the described amine polyol polyisocyanate binder collapsed and flowed out of the aluminum casting part without the shaking mechanism having to be used and without any external mechanical energy having to be applied. The dropout rate was 1001.

EXAMPLE 26 A solution having a solids content of 58.51 of a phenolic polyol, which is commercially available as PEP was prepared by dissolving the polyol in HISOL 10. The title is called Part I. Resin This solution is a polymeric isocyanate solution, solids. 75%, based on Mondur MR, marketed by Mobay, was prepared using a solvent mixture consisting of 19% Texaco 75U5, an aromatic solvent and 61 kerosene.

The isocyanate solution is called Part II. An almost stoichiometric amount of polyisocyanate for complete reaction with the hydroxyl groups in the polyol was used. NO 15 oxide, an inert carrier gas. Wedron 5010 sand (washed and dried fine-grained sand, AFSGEN 66) was placed in a suitable mixer. Part I was mixed with the sand until a homogeneous coating was obtained. Part II was added to the coated sand and mixed with it until a homogeneous sand mixture was obtained. 1.8 weight! sand was used, calculated on the total binder (equal amounts of Part I and of Part II).

The mixture of sand, polyol and polyisocyanate was blown into a conventional core cavity or box to produce standardized test cores known as "dog bones" and intended for tensile tests. The test nuclei in the form of dog bones were cured by being exposed to a catalyst in the form of a tertiary amine. The amine catalyst, dimethylethylamine, is suspended in carbon. The cores were exposed to the amine catalyst for about 1 second (gas time) and then immediately taken out of the core box. The tensile strength values in kg / cm2 were 12.7 immediately (1 min.) After removal from the box, 29.8 after 20 hours.

The "dog bone" cores were used in shaking studies with alu- Seven tensile briquettes (dog bone) an- The mold contained a gate system. The shape is such that it gives hollow castings with a metal thickness of about 6.ü mm on all sides. 15.8 after U hours and minimum casting details. arranged in a form.

An opening at one end of the casting member is provided for removing the core from the casting member. Molten aluminum with a temperature of about 70,000 made from aluminum raw material was poured into the mold. the aluminum casting details out through the gate system and were removed from the mold for shaking attempts.

The shaking experiments are performed in such a way that a casting part is placed in a 3.8 liter container. After cooling for about 1 hour, the container was placed on a shaking mechanism and subjected to shaking for two minutes.

The weight of the sand core removed from the casting part in this way is compared with the original weight of the sand core, and the percentage elimination is calculated. The sand core bonded with the phenolic resin-polyisocyanate binder described above could not be shaken out after being subjected to the aforementioned shaking procedure. The shaking was thus 01. A comparison between this example and previous examples shows the advantages in terms of shaking when using an amine polyol in a Cold Box system compared to other polyols used in a Cold Box system, when low temperature casting is performed.

Claims (20)

zs 7905016-7 PATENT REQUIREMENTS A process for casting light metals, which comprises forming a casting mixture by: (a) forming said mixture to form a mold; (b) allowing said mixture to harden after said mold is formed; (c) forming a shaped light metal casting body by using said cured shaped mixture and by casting molten light metal in contact with said shaped mixture; and (d) removing the cured shaped mixture from the light metal casting body, characterized in that said casting mixture comprises a ballast material, a polyisocyanate component and a polyol component, consisting essentially of an amine polyol, in which mixture the ballast material amounts to at least 90% by weight . Process according to Claim 1, characterized in that the mixture also contains a catalyst for urethane formation. A method according to claim 1, characterized in that the mixture is cured by a No-Bake method. Process according to any one of the preceding claims, characterized in that the amount of polyisocyanate is about 20 to 300% by weight based on the weight of the amine polyol and the total amount of polyisocyanate and amine polyol constitutes 0.7 to 2.5% by weight of the aggregate material. 5. A process according to any one of the preceding claims, characterized in that the amine polyol comprises at least one compound selected from the group triethanolamine and the reaction of the propylene oxide with an amine selected from the group diethylenetriamine, triethylenetetramine or ethylenediamine or mixtures thereof. 6. A process according to claim 2, characterized in that the catalyst is triethylenediamine. Method according to one of the preceding claims, characterized in that the ballast material is dried sand. A process according to any one of claims 1-5, characterized in that the amine polyol comprises a reaction product of an amine compound and an alkylene oxide. 7905016-7 26 9. A process according to claim 8, characterized in that the amine compound is ammonia. 10. A process according to claim 8, characterized in that the amine compound is an aromatic amine. 11. A process according to claim 8, characterized in that the amine compound is an aliphatic amine. 12. A process according to claim 8, characterized in that the alkylene oxide is propylene oxide. 13. A process according to claim 8, characterized in that the alkylene oxide is ethylene oxide. 14. A process according to any one of the preceding claims, characterized in that the polyisocyanate is present in solution in an organic solvent. Process according to any one of the preceding claims, characterized in that the amine polyol is present in solution in an organic solvent. Process according to any one of the preceding claims, characterized in that the amine polyol is present in aqueous solution. Process according to one of the preceding claims, characterized in that the casting of the light metal is carried out at a temperature below 1093 ° C. Process according to any one of the preceding claims, characterized in that the polyol consists essentially of an amine polyol and a phenolic resin. Process according to any one of the preceding claims, characterized in that the polyol comprises an amine polyol and a non-aromatic hydroxy compound. Method according to one of the preceding claims, characterized in that the light metal is aluminum.