DK170551B1 - Method of casting lightweight metal objects - Google Patents

Description

DK 170551 B1

The present invention relates to a method for casting lightweight metal articles which are formed using non-heat cured urethane binder containing moldings which crumble after casting the metal articles. The moldings consist of a molding binder of a mixture of polyols containing amine-based polyols, polyisocyates and a casting aggregate which is cured under the action of a urethane catalyst. The castings used for the casting of lightweight metal objects exhibit superior crumbability and erosion.

Urethane cold-box binders are known for use in bonding aggregates useful as cast cores and molds. U.S. Patent No. 3,409,579 describes Example 15 of such a cold-box binder composition and its use in the manufacture of cores and molds for molding purposes.

U.S. Patent No. 3,645,942 discloses a method of making non-heat-curing urethane binder-containing moldings. These moldings are formed by mixing a polyisocyanate prepolymer component, a non-drying castor oil and an aromatic polyisocyanate, and an amine polyol component with sand, under the same action of a catalyst. However, United States Patent No. 3,645,942 does not mention the particular problems that arise in connection with the casting of lightweight metal objects.

Furthermore, non-thermosetting urethane binders are known for use in bonding aggregates useful as mold cores and molds. U.S. Patent No. 3,676,392 describes an example of such a non-thermosetting binder composition and its use in the manufacture of cores and molds for molding purposes.

For a long time in the foundry industry, there has been a desire for a non-curing and cold-box binder for the production of molds for light metals such as aluminum and DK 170551 B1 2 magnesium. The previously known non-thermosetting and cold-box binders are not capable of providing cores and molds for casting these lightweight metals with the required core and mold properties as well as good extensibility. When sufficient binder is used to obtain a usable strength and abrasion resistance, the cores and molds do not degrade satisfactorily at the casting temperatures of the light metals. *

Ie they exhibit poor extravagance. It has been an ongoing problem to find a binder which, on the one hand, provides strong, non-brittle cores and molds and, on the other hand, is well degraded by the casting temperature of aluminum and magnesium to produce easy extrusions.

Thus, the present invention provides a method in which non-thermosetting urethane and cold-box binders are used. They are used in the manufacture of cores and molds which have strength and non-brittleness, but which are still well degraded at low molding temperatures, ie. below cast metal temperatures. The cores and molds exhibit the combination of strength and light agility at the molding temperatures of lightweight metals such as aluminum and magnesium. The invention is characterized by the characterizing part of claim 1.

The present invention is based in part on the autocatalytic nature of amine polyols.

It has been found that a urethane binder formed as a reaction product of a polyisocyanate and an amine-based polyol can be used to prepare cores and molds. The binder can be rapidly cured 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 used with a polymeric isocyanate to prepare a non-curing or cold-box binder which, after mixing with sand or another suitable casting assembly and curing, forming cores and molds which have excellent working properties, ie. strength, abrasion resistance and DK 170551 B1 3 non-brittleness. These properties combine with excellent shaking properties when utilized by casting non-ferrous metals. This combination of good working properties and excellent extensibility is especially significant and unique when the binder is used to prepare cores to be used in low temperature casting. A catalyst is used to cure the components of the binder system. Suitable catalysts for the cold-box binder are gaseous tertiary amines or amines which can be introduced as a gas. Trimethylamine, dimethylethylamine and trimethylamine are preferred catalysts.

The resin compositions find use as a two-component composition or system. Component one is the amine polyol. Component two is the polyisocyanate. Both components are in liquid form and are generally organic solvent solutions. At the time of use, ie. when the urethane binder is formed, the amine polyol component and the polyisocyanate component are combined and used for the intended use. For foundry use, ie When using the compositions 20 as a binder for cores and molds, it is first preferred to mix a component with a casting assembly such as sand. Then, the second component is added and after obtaining a uniform distribution of the binder on the assembly, the resulting molding mixture is formed into the desired shape. The molded product can be set aside immediately and will cure to form a core or mold at room temperature. The compositions are generally autocatalytic to some extent. That is, when the amine polyol and the isocyanate are combined, the reactivity of the polyol with the isocyanate is such that the reaction proceeds rapidly. The reactivity of the amine polyol and the polyisocyanate depends on the reactivity of the polyol. The molded product may also be cured to form a core or mold by contacting a gaseous catalyst.

Although the compositions are autocatalytic, 35 known liquid amine catalysts and metallic catalysts are used in the non-heat curing DK 170551 B1 4 in the urethane technology. In selecting an appropriate catalyst, the conditions of the nucleation process, e.g. working time and stripping time, set as desired.

Also known in the art of cold-box technology are 5 gaseous amine catalysts. The actual curing step can be performed by suspending a tertiary amine in an inert gas stream and passing the gas stream containing the tertiary amine through the mold under a sufficient pressure to penetrate the molded mold until the resin is cured. The binder intermediate compositions require exceptionally short cure times to obtain acceptable tensile strengths, which is a property of very great commercial importance. Optimal curing times are easily determined experimentally. Since only catalytic concentrations of the tertiary amine are necessary to effect the cure, a highly diluted stream is generally sufficient to obtain the cure. However, concentrations of the tertiary amine above that necessary to effect the cure are not detrimental to the resulting cured product. Inert gas streams, e.g.

20 air, carbon dioxide or nitrogen containing from 0.01 to 20% by volume of tertiary amine. Usually 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 vapor form or if suspended in a gaseous medium and then passed through the mold. Although ammonia, primary amines and secondary amines show some activity in producing a reaction at room temperature, they are substantially inferior to the tertiary amines. Functionally substituted amines such as dimethylethanolamine fall within the definition of tertiary amines and can be used as curing agents. Functional groups which do not affect the action of the tertiary amine are e.g. hydroxyl groups, alkoxy groups, amino and alkyl γ amino groups, ketoxy groups and thio groups.

• 'i $. ··? · DK 170551 B1 5

The amine polyols used to form the urethane binder compositions are usually prepared as the reaction product of an alkylene oxide and an amine compound. The term "amine polyol" is used herein to identify such reaction products, but is not specifically limited to such synthetic methods. Generally, any polyol containing at least one or more tertiary amine groups is considered to fall within the term "amine polyol". The alkylene oxides used to prepare the amine polyols are preferably ethylene oxide and propylene oxide. However, it appears possible to use other alkylene oxides as well. The amount of alkylene oxide in moles per moles of the amine compound can vary substantially. It is believed that the degree of alkoxylation does not reduce the ability of the resulting amine polyol to act as a binder.

The amine compounds which are reacted with alkylene oxides to form amine polyols useful in the present binder compositions are e.g. ammonia and mono- and polyamino compounds with primary and secondary amino nitrogen.

Specific examples are e.g. aliphatic amines such as primary alkyl amines, ethylenediamine, diethylenetriamine and triethylenetetramine, cycloaliphatic amines, aromatic amines such as o-, m- and p-phenylenediamines or aniline formaldehyde resins. Mixtures of the above-mentioned amine polyols may also be used. Furthermore, a mixture of amine polyols with other polyols, i. non-amine polyols, useful. In general, it is believed that amine-containing compounds which, when alkoxylated, give a polyol having two or more reactive hydroxyl groups are useful for the compositions of the present invention.

The nature of the polyol constituent used influences the core manufacturing process conditions. 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 feature of the binder 35's "bench-life" time. The "bench-life" time, which corresponds to the working time of a non-heat curing system, is the period in which the resin-coated sand can be used. After the binder is distributed to an aggregate, the binder begins to react. After a certain period of time, the reaction has proceeded to such an extent that the resin-coated sand can no longer be used. The sand coated with the binder is then said to be "shot". The elapsed time from the sand is coated with the resin until the sand mixture is "shot" is known as the "bench-life" time in a cold-box system. It has been found that the use of aromatically initiated 10 amine polyols results in an unexpected increase in the "bench-life" time of the resin coated sand. This unexpected result is of great benefit and is considered important.

As mentioned above, it has been found useful to blend or mix an amine polyol with another polyol, a polyhydroxyl compound capable of reacting with a polyisocyanate. This utility is particularly evident in the "strengths out of the box" obtained after exposure of the binder to the catalyst. Particularly preferred are the hydroxy-containing phenolic resins disclosed in U.S. Patent No. 3,485,797, known in the foundry industry as "PEP" ® resins.

The second component or component of the binder composition contains an aliphatic, cycloaliphatic or aromatic polyisocyanate having preferably 2-5 isocyanate groups.

If desired, mixtures of polyisocyanates may be used.

Isocyanate prepolymers prepared by reacting an excess of polyisocyanate with a polyhydric alcohol, e.g. a prepolymer of toluene diisocyanate and ethylene glycol. Suitable polyisocyanates are e.g. aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as 4,4'-dicyclohexylmethane diisocyanates or aromatic polyisocyanates such as 2,4- or 2,6-toluene diisocyanate, diphenylmethane diisocyanate or dimethyl derivatives thereof. Further examples of suitable polyisocyanates are 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate, xylylene diisocyanate and their methyl derivatives, polymethylene polyphenylisocyanates and their methyl derivatives, and chloro-phenylene-2,4-diisocyanate. Although all polyisocyanates react with the amine polyol to form a crosslinked polymer structure, the preferred polyisocyanates are aromatic polyisocyanates, especially diphenylmethane diisocyanate, triphenylmethane triisocyanate and mixtures thereof.

The polyisocyanate is generally used in approximately a stoichiometric amount, i.e. in a sufficient concentration to effect cure of the amine polyol. However, it is possible to deviate from this amount within certain limits and in some 10 cases benefits can be obtained. Generally, the polyisocyanate is used in an amount of 10-500% by weight based on the amine polyol. Preferably 20 to 300% by weight of polyisocyanate is used on the same basis. The polyisocyanate is used in liquid form. Liquid polyisocyanates can be used in undiluted form.

Solid or viscous polyisocyanates are used in the form of organic solvent solutions, 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 both, does not significantly participate in the reaction between the isocyanate and the amine polyol, it can influence the reaction. Thus, the difference in polarity between the polyisocyanate and the amine polyol limits the choice of solvents with which both components are compatible. Such compatibility is necessary to achieve a complete reaction and cure of the binder compositions. Polar solvents of either protic or aprotic type are good solvents for the amine polyol. Therefore, it is preferred to use solvents or combinations of solvents where the solvent (s) of the polyol and of the polyisocyanate are compatible when mixed. In addition to compatibility considerations, the solvents are selected for either the polyol or polyisocyanate so as to obtain low viscosity, low air, high boiling point and "internal". 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 within the range of from about.

137 ° C to approx. 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 the art are classified as "coupling solvents" and include furfural, "Cellosolve" ®, glycol diacetate, butyl "10" Cellosolve "acetate, isophorone and the like. It may also be possible to use some reactive polyols as a solvent. Furthermore, it should be noted that water has been found to be a suitable solvent for the amine polyol under certain conditions.

The binder components are then combined and mixed with sand or a similar casting assembly to form the molding mix, or the molding mix may be formed by sequential mixing of the components with the aggregate. Methods of distributing the binder on the aggregate particles are well known in the art. The molding mix may optionally contain other ingredients such as iron oxide, ground flax fiber, wood chips, beech or heavy-meltable powders. The unit, e.g. sand is usually the main constituent and the binder constituent constitutes a relatively smaller amount. Although the sand used is preferably dry sand, some moisture can be tolerated. This is especially the case if the solvent used is immiscible with water or if an excess of the polyisocyanate is used relative to that needed for the cure, since such excess polyisocyanate will react with the water. and water is a useful solvent for the amine polyol.

9

As indicated above, the good shaking properties or good crumbability of cores made using the binder herein is considered to be a significant recognition. The binders herein are easily decomposed or broken down, thereby allowing separation of the core from the molded material · · 1 | ΐ »= 13 DK 170551 B1 9. For molding at low temperatures, e.g. at about. 980 ° C or below, shaking is a major problem. Generally, non-ferrous metals, including aluminum and magnesium, are cast at these temperatures. If the binder is not degraded, this causes great difficulty in removing the sand from the molded article. Thus, cores with a low degree of shaking or crumbling ability, i.e. low degree of binder degradation, more time and more energy to remove the sand from the cast. The use of the 10 binder compositions herein results in many cases in an actual 100% shaking without the application of any external energy. The improvement in the shaking can be attributed to the presence of the amine polyol in the binder composition. As will be apparent to those skilled in the art, the ability of any 15 cores to shake out depends to some extent on the amount of binder used to bond the sand particles to a coherent form.

The percentage of binder used, based on the weight of the sand, depends on the desired core properties required by the binder system. Obviously, as the amount of binder in the system is increased, the tensile strength of the core generally increases. Thus, the binder level can be varied within reasonable limits to achieve desired properties. According to the present invention, a preferred range of the binder is from 0.7% to 2.5%, based on the weight of sand. However, it is possible to use as little as 0.5% and as much as 10% binder and still obtain properties which are advantageous for certain applications. However, it has also been found that as the binder level is increased, the degree of shaking can be reduced for higher binder levels.

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

Example 1.

DK 170551 B1 10

An aromatic amine polyol is prepared by propoxylating one mole of m-phenylenediamine with 4.2 moles of propylene oxide. A 40% solids solution of the aromatic amine polyol is prepared by dissolving the polyol in an aliphatic solvent, butyl "Cellosolve" ®. This solution is referred to as "Part I". A 75% solids polymeric isocyanate solution based on Mond "Mondur" MRI, a mixture of diphenylmethane diisocyanate and polymethylene polyphenylisocyanate and commercially available from Mobay, is prepared using an aromatic solvent commercially available as "HISOL" * 10th The isocyanate solution is designated "Part II". An almost stoichiometric amount of polyisocyanate is used to react completely with the hydroxy groups of the polyol.

15 "Wedron" 5010 sand (washed and dried, fine-grained quartz sand, AFSGFN 66) is placed in a suitable mixer. "Part I" is mixed with the sand until a uniform coating is obtained. Included in "Part I" is a urethane catalyst, triethylene diamine, which is commercially available under trademark Φ 20 "DABCO". This catalyst is a well-known urethane catalyst. 0.8% catalyst is used, based on the weight of "Part I". "Part II" is added to the coated sand and mixed until a homogeneous sand mixture is obtained. A total of 1¾% binder ("Part I" and "Part II") used on the sand is used.

The mixture of sand, polyol, catalyst and polyisocyanate is placed in a seed box and standard tensile strength tests known as "meat bones" are prepared. A workability time of 70 minutes and strip time of 110 minutes are obtained. The tensile strength after 24 hours is 1.59 x 106 N / m2.

P

The 30 "meat bone" cores are used for shredding studies with cast aluminum blanks. Seven tensile strength tests (meat bones) are placed in a mold. The mold is incorporated into an inlet system.

The mold is designed to provide hollow molded workpieces with a metal thickness of approx. 6.35 mm on all sides. There is an opening DK 170551 B1 11 at one end of the molded blank for removing the core from the blank. Melted aluminum at approx. 705 ° C made from aluminum bars is poured into the mold. After cooling for approx. For 1 hour, the cast aluminum blanks are broken from the inlet system and removed from the mold for shaking tests.

The shaking tests are performed by placing a molded blank in a container with a volume of approx. 3.8 liters. The container is placed on a shaking mechanism and shaken for 2 minutes. The weight of the sand core which is removed from the molded workpiece in this way is compared to the initial weight of the sand core and the percentage shaking is calculated. The sand left in the workpiece after the above-described shaking is removed by scraping and also weighed. The sand core bonded with the amine polyol-polyisocyanate catalyst binder 15 described above crumbles and flows out of the cast aluminum blank without the use of the shaking mechanism and without the application of any external mechanical energy. The outbreak is 100%.

Examples 2-3.

Using the method 20 described in Example 1, meat bone test cores are prepared using the ingredients and methods described below. The cores are used for shredding studies for cast aluminum blanks as described in Example 1.

DK 170551 B1 12

Example 2 Example 3

Sand "Wedron" "Wedron" 5010 5010

Amine Component Alkylene - - * oxide

Mole ratio AO: amine

Amine polyol "Pluracol" c c "Pluracol" d 10 767 795

Poly- "Mondur" * MR "Mondur" * MR

isocyanate

Solution 40% 35% agent in 15 amine polyol "HISOL" * 10 "HISOL" ® 10

Solution 44% e 35% e agent in polyisocyanate

Catalyst (1) 1.4% (1) 1¾% 20 Processing 25 min. 7 min.

similarity "Strip" - time 31 min. 10.5 min.

Percentage 1.5% 1.5% binder Part I 50% 50%

Part II 50% 50%

Tensile strength 1 N / m2 2 hours 1.55x1O6 - 30 3 hours - - 1.54x106 4 hours - - 1.45x1O6 24 hours 2.54x106 2.21x106

Equip 92% 100% similarity 35 Cores made as described above crumble and flow out of the molded blank without the use of a shaking mechanism and without the application of any external mechanical energy.

1) 50% phenylpropylpyridine and 50% of a lithium salt of a carboxylic acid.

DK 170551 B1 13 c "Pluracol" ® 767 is a trademark of a propoxylated aromatic amine based polyol commercially available from BASF Wyandotte.

d "Pluracol" ® 795 is a trademark of an ethoxylated aromatic 5 amine based polyol commercially available from BASF Wyandotte.

eA mixture of "HISOL ·" ® 10 and petroleum.

Example 4

An aromatic amine polyol is prepared by propoxylating a mole of 10-phenylenediamine with 4.2 moles of propylene oxide. A solution with 40% solids content of the aromatic amine polyol is prepared by dissolving the polyol in isophorone. This solution is referred to as "Part I". A polymeric isocyanate, "Mondur" ® MR is referred to as "Part II". An almost stoichiometric amount of polyisocyanate is used to react completely with the hydroxyl groups of the polyol.

φ "Wedron" 5010 sand (washed and dried, fine-grained quartz sand, AFSGFN 66) is placed in a suitable mixer. "Part I" is mixed with the sand until a uniform coating is obtained. In "Part 20 I" is incorporated a 33% solution in dipropylene glycol of a urethane catalyst, triethylenediamine, which is commercially available under the trademark "DABCO". This catalyst is a well-known urethane catalyst. 1.0% catalyst is used, based on the weight of "Part I". "Part II" is added to the 25 coated sand and mixed until a homogeneous sand mixture is prepared. A total of 1¾% binder (55% "part I" and 45% "part II"), based on the weight of sand, is used.

The mixture of sand, polyol, catalyst and polyisocyanate is placed in a core box and standard tensile strength tests known as "meat bones" are prepared. A workability time of 9 minutes and a strip time of 20 minutes are obtained.

DK 170551 B1 14

The tensile strengths after 2 hours and 24 hours are 2.01 x 106 N / m2 and 2.16 x 106 N / m2 respectively.

The "meat bone" cores are used for shredding studies with cast aluminum blanks. Seven tensile strength tests (meat bones) are placed * 5 in one form. The mold is placed in an inlet system. The mold is intended to produce hollow molded workpieces having a metal thickness of approx. 6.35 mm on all sides. There is an opening at one end of the molded blank for removing the core therefrom.

Melted aluminum at approx. 705 ° C made from aluminum-10 bars is poured into the mold. After cooling for approx. For 1 hour, the cast aluminum blanks are broken from the inlet system and removed from the mold for shaking studies.

The shaking tests are done by placing a molded blank in a container with a volume of approx. 3.8 liters. The container is placed on a shaking mechanism and shaken for 2 minutes.

The weight of the sand removed from the workpiece in this way is compared to the initial weight of the sand core and the percentage shaking is calculated. The remaining sand after the above-described shaking of the workpiece is removed by scraping and also weighed. The sand core bonded with the above-described amine polyol-polyisocyanate catalyst binder crumbles and flows out of the cast aluminum blank without the use of the shaking mechanism and without the application of any external mechanical energy. The outbreak is 100%.

Example 5.

Using the method described in Example 4, meat bone test cores are prepared using the ingredients and methods described below. The cores are used for shaking examination using molded aluminum blanks as described in Example 4.

Example 5 DK 170551 B1 15

Sand "Wedron" 5010

Amine component Aniline 5 Alkylene-Propylene oxide oxide

Mole ratio AO: amine 2.2: 1

amine polyol

Polyisocyanate "Mondor" * MR

Solvent 60% (X) in amine polyol

Solvent None in Polyisocyanate Catalyst 1% "Dabco"

Edit for 70 min.

strip time lightness 140 min.

Percentage of 1.5% binder

Part I 61%

Part II 39%

Tensile strength in N / m2 24 hours 1.24x1O6 25 Shakeout 74% X) A mixture of butyl "Cellosolve" acetate (40%) and "HISOL" ® 10 (20%).

Cores made as described above crumble and flow out of the molded blank without the use of a shaking mechanism, 30 supplied by external mechanical energy.

Example 6

An amine polyol is prepared by propoxylating 1.0 mole of m-phenylenediamine with 6.0 moles of propylene oxide. A solution containing 40% solids content of the amine polyol is prepared by dissolving the polyol in a mixture solvent of 40% isophorone, 16.5% of an aromatic solvent and 3.5% of petroleum. This solution is referred to as "Part I". A polymer DK 170551 B1 16 isocyanate solution having a solids content of 75% based on "Mondur" ® MR commercially available from Mobay is prepared using an aromatic solvent "HISOL ·" ® 10. The isocyanate solution is designated "Part II". An almost stoichiometric amount of polyisocyanate is used to completely react with the hydroxy groups of the polyol.

"Wedron" 5010 sand (washed and dried fine-grained quartz sand, AFSGFN 66) is placed in a suitable mixer. "Part I" is mixed with the sand until a uniform coating is obtained. "Part II" 10 is added to the coated sand and mixed until a homogeneous sand mixture is obtained. A total of 1¾% binder is used (equal amounts of "Part I" and "Part II"), based on the weight of sand.

The mixture of sand, polyol and polyisocyanate is blown into a conventional core cavity or box for the production of standard tensile Turkish sample cores known as "meat bones". The meat bone test cores are cured by exposing the cores to a tertiary amine catalyst. The amine catalyst, dimethylethylamine, is suspended in carbon dioxide, an inert carrier gas. The cores 20 are exposed to the amine catalyst for approx. 20 seconds (gassing time) and left in the core box for 10 minutes (resting time) before removing the core from the box. Tensile strengths of 0.17 x 106 N / m2 are measured immediately after removal of the box, 0.50 x 106 N / m2 after 1 hour and 0.93 x 10s N / m2 after 24 hours.

The 25 "meat bone" cores are used for shredding experiments with cast aluminum blanks. Seven tensile strength tests (meat bones) are placed in a mold. The mold is connected to an inlet system. The mold is intended to produce hollow molded articles having a metal thickness of approx. 6.35 mm on all sides. There is an opening at one end of the blank for removing the core from the molding. Melted alumi-? nium at approx. 705 ° C made from aluminum bars is poured into the mold. After cooling for approx. For 1 hour, the aluminum blanks' are broken from the inlet system and removed from the mold for shaking examination.

DK 170551 B1 17

Shaking tests are carried out by placing a molding blank in a container with a volume of approx. 3.8 liters. The container is placed on a shaking mechanism and shaken for 2 minutes. The weight of the sand removed from the cast in this way is compared to the initial weight of the sand core and the percentage shaking is calculated. The sand remaining in the cast after the above-described shaking is removed by scraping and also weighed. The sand core bonded with the above-described amine polyol-polyisocyanate binder crumbles and flows out of the aluminum cast without the use of the shaking mechanism and without the use of any external mechanical energy. The shake is 100%.

Examples 7-11.

Using the methods 15 described in Example 6, test cores are prepared and tested using the ingredients and methods described below.

DK 170551 B1 18

Example 7 Example 8 Example 9 Example 10 Example 11

Sand "Wedron" "Wedron" "Wedron" "Wedron" "Wedron 5010 5010 5010 5010 5010

Amine Aniline o-phenylene m-phenylene m-phenyl en- »CURITHANE1,103 5 compounds diamin en aniline * formaldehyde resin supplied by Upjohn 10 Alkylene-Propylene-Propylene-Propylene-Propylene-Propylene Oxide Oxide Oxide Oxide Oxide

Mole ratio AO: Amine 2: 1 4.2: 1 4.2: 1 8: 1 4: 1

Amine Polyol Poly- "Mondur" * "Mondur" * "Mondur" * "Mondur" * "Mondur" *

isocyanate MR MR MR MR MR

Solvent in amine polyol 60% (1) 60% Iso-60% Iso-60% (1) 60% Iso-phoron phoron phoron

Solution nothing 25% (2) 25% 25% (2) no agent in "HISOL" * 10 polyisocyanate

Catalyst Trimethyl-Dimethyl-Dimethyl-Dimethyl-Trimethyl-amine Ethylamine Ethylamine Ethylamine Amine Suspended Suspended Suspended in CO 2 in CO 2 in CO 2

Gassing time 10 sec. 10 sec. 10 sec. 20 sec. 5 sec.

Resting time 5 min. 3 min. 10 min. 10 min. 2 min.

3 0 Tensile strength in N / m2 Right after removal of box 0.21x106 0.34x106 0.03x106 0.72x106 0.21x106 35 1 hour - - 0.69x106 0.49x106 0.72x106 - - 24 hours 0.62x106 0, 59x106 0.80x106 - 0.34x106

Total amount of binder 1.5% 1.5% 1.5% 1.5% 1.5% 5

Part I 75% 50% 50% 50% 75% 40 Part II 25% 50% 50% 50% 25%

Extravagance 100% 100% 100% 100% 100% DK 170551 B1 19

Cores made as described above crumble and flow out of the mold without the use of a ratchet mechanism and without the application of any external mechanical energy.

(1) A mixture of isophorone (40%), aromatic solvents (16.5%), petroleum (3.5%).

(2) A mixture of an aromatic solvent commercially available under the trade name "Texaco Solvent" 7545 (19%) and petroleum (6%).

Example 12.

An amine polyol is prepared by propoxylating 1.0 mole of m-phenylenediamine with 8.0 moles of propylene oxide. A phenolic polyol Φ commercially available as "PEP" resin is added to the amine polyol to produce a polyol blend. The ratio of o-amine polyol to non-amine polyol is 2: 1. A solution of 60% solids content of the polyol is prepared by dissolving the polyol mixture in isophorone solvent. The solution is referred to as "Part I". A polymeric isocyanate solution with 75% solids content, based on "Mondur" ® MR commercially available from Mobay, is prepared using a solvent mixture containing 19% Texaco 7545, an aromatic solvent, and 6% petroleum. The isocyanate solution is designated "Part II". An almost stoichiometric amount of polyisocyanate is used to react completely with the hydroxyl groups of the polyol.

25 "Wedron" 5010 sand (washed and dried fine-grained sand, AFSGN 66) is placed in a suitable mixer. "Part I" is mixed with the sand until a uniform coating is obtained. "Part II" is added to the coated sand and mixed until a homogeneous sand mixture is formed. A total of 1 1/2% of binder 30 (44% "Part I" and 56% "Part II") based on the weight of sand is used.

The mixture of sand, polyol and polyisocyanate is blown into a conventional core cavity or box to produce standard tensile strength test cores known as "meat bone". The meat bone test cores are cured by exposing the cores to a tertiary amine catalyst. The amine catalyst, dimethylethylamine, is suspended in carbon dioxide, an inert carrier gas. The nuclei are exposed to the amine catalyst for approx. 5 seconds (gassing time)? and leave in the core box for 1 minute (rest time) before removing the core from the box. Immediately after ^ removal from the box, the tensile strengths are approx. 0.40 x 106 N / m2, after 1 hour approx.

1.38 x 106 N / m2 and at the time of casting approx. 1.45 x 10 106N / m2.

The "meat bone" cores are used for shredding studies with aluminum castings. Seven tensile strength tests (meat bones) are placed in a mold. The mold is placed in an inlet system. The mold is intended for making hollow castings having a metal thickness of approx. 6.35 mm on all sides. An aperture is provided at one end of the casting for removing the core therefrom. Melted aluminum at approx. 705 ° C made from aluminum bars is poured into the mold. After cooling for approx. For 1 hour, the aluminum moldings are broken from the inlet system and 20 removed from the mold for shaking studies.

The shaking tests are performed by placing a molding blank in a container of approx. 3.8 liters. The container is placed on a shaking mechanism and shaken for 2 minutes. The weight of the sand core removed from the molding in this way is compared to -25 is equal to the initial weight of the sand core and the percentage equipments are calculated. The sand remaining in the mold after the above-described shaking is removed by scraping and also weighed. The sand core bonded with the above-described amine polyol-polyisocyanate binder crumbles and flows out of the aluminum die without the use of the shaking mechanism and without the application of any external mechanical energy. The extravagance »is 100%.

y Ί .....

DK 170551 B1 21

Example 13 Example 14

Sand "Wedron" 5010 "Wedron" 5010

Amine compound "Curithane" 103

Alkylene oxide Propylene oxide 5 Mole ratio of alkylene oxide: amine

Amine polyol "Pluracol" * 7351

Non-amine polyol Phenolic polyol Phenolic polyol

Amine polyol ratio: 10 non-amine polyol 2: 1 2: 1

Polyisocyanate "Mondur" ® MR

Solvent in polyol mixture 40% Butyl "Cello 40% Butyl" Cello solve "® acetate solve" * - Acetate 15 Solvent in polyisocyanate 25% "Aromatic 25% petroleum solvent 7545", 6% petroleum

Catalyst Trimethylamine Trimethylamine 20 Gasification time 5 sec. 5 sec.

Resting time 1 min. 1 min

Tensile strength in N / m2 0.31x106 0.36x106 1 hour 0.88x10® 0.86x106 4 hours 0.76x106 - - 25 molding time l, 12x106 0.88x106

Total binder 1.5% 1.5%

Part I 44% 50%

Part II 56% 50%

Extravagability 100% 48% 30 1 An amine-based polyol from BASF (presumed to be ethoxylated and aromatic).

The sand core bonded with the amine polyol derived from propoxylated "Curithane" 103, an aniline-formaldehyde resin supplied by Upjohn, crumbles and flows out of the aluminum cast-35 blank without the use of the shaking mechanism and without the use of external energy. The sand core based on "Pluracol" ® 735 is shaken to obtain the specified degree of shaking.

Example 15

22 DK 170551 B1

An amine polyol is prepared by propoxylating 1.0 mol of ethylenediamine with 8.0 mol of propylene oxide. A solution having a solids content of 50% of the amine polyol is prepared. v 5 By dissolving the polyol in a mixture of solvent 30% isophorone, 16.5% of an aromatic solvent and 3.5% ✓ petroleum. This solution is referred to as "Part I". A polymeric isocyanate solution containing 75% solids, based on Mond "Mondur" MRI commercially available from Mobay, is prepared using an aromatic solvent, "Texaco 7545" (19%) and petroleum (6%). The isocyanate solution is designated "Part II". An almost stoichiometric amount of polyisocyanate is used to react completely with the hydroxy groups of the polyol.

15 "Wedron" 5010 sand (washed and dried fine-grained quartz sand, AFSGFN 66) is placed in a suitable mixer. "Part I" is mixed with the sand until a uniform coating is obtained. "Part II" is added to the coated sand and mixed until a homogeneous sand mixture is prepared. A total of 1¾% 20 binder is used (equal parts "part I" and "part II"), based on the sand weight.

The blend of sand, polyol and polyisocyanate is blown into a conventional core cavity or box to produce standard feature turkey core samples known as "meat bones". The bone marrow test cores are cured by exposing the cores to a tertiary amine catalyst, trimethylamine. The nuclei are exposed to the amine catalyst for approx. 10 seconds (gassing time) and allow to remain in the core box for 5 minutes (rest time) before removing the core from the box. The tensile strengths are approx. 0.55 x 106 N / m2 30 minutes after gassing and approx. 0.93 x 106 N / m6 after ^ 24 hours.

The meat countertops are used for shredding studies with aluminum castings. Seven tensile strength tests (meat bones) are placed in a mold. The mold is connected to an inlet system. The mold is 3- DK 170551 B1 23 intended for the manufacture of hollow castings with a metal thickness of approx. 6.35 mm on all sides. The molding is provided at one end with an opening for removing the core from the molding. Melted aluminum at approx. 705 ° C made out of 5 from aluminum bars is poured into the mold. After cooling for approx.

For 1 hour, the aluminum moldings are broken from the inlet system and removed from the mold for shaking examination.

Shaking tests are carried out by placing a molding blank in a container with a volume of approx. 3.8 liters. The container 10 is placed on a shaking mechanism and shaken for 2 minutes. The weight of the sand core removed from the cast in this way is compared to the initial weight of the sand core and the percentage shaking is calculated. Sand remaining in the mold after shaking as described above is removed by scraping and also weighed. The sand core bonded with the above-described amine polyol-polyisocyanate binder crumbles and flows out of the aluminum mold without the use of a ratchet mechanism and without the application of any external mechanical energy. The outbreak is 100%.

Example 16. (Comparative Example)

A solution with 58.5% solids content of phenolic polyol Φ commercially available as "PEP" resin is prepared by dissolving the polyol in "HISOL" ® 10. This solution is referred to as "Part I". A polymeric isocyanate solution having a solids content of 75%, based on "Mondur" ® MR, commercially available from Mobay, is prepared using a solvent mixture consisting of 19 "Texaco 7545", an aromatic solvent, and 6% petroleum. . The isocyanate solution is designated "Part II". An almost stoichiometric amount of polyisocyanate is used to react completely with the hydroxy groups of the polyol.

"Wedron" 5010 sand (washed and dried fine-grained sand, AFSGEN 66) is placed in a suitable mixer. "Part I" is mixed with the sand until a uniform coating is obtained. "Part II" is added DK 170551 B1 24 to the coated sand and mixed until a homogeneous sand mixture is obtained. A total of 1.8% binder is used (equal amounts of "Part I" and "Part II"), based on the sand weight.

The mixture of sand, polyol and polyisocyanate is blown into a conventional core cavity or box to produce standard tensile strength test cores known as "meat bone". The meat bone test cores are cured by exposing the cores to a tertiary amine catalyst. The amine catalyst, dimethylethylamine, is suspended in carbon dioxide, an inert carrier gas. The nuclei are exposed to the amine catalyst for approx. 1 second (gassing time) and immediately removed from the core box. The tensile forces for 1 minute after removal from the box approx. 1.25 x 106 N / m6, after 4 hours approx.

1.55 x 106 N / m2 and after 20 hours approx. 2.05 x 106 N / m2.

The meat bone cores are used for shaking tests on 15 aluminum castings. Seven tensile strength tests (meat bones) are placed in a mold. The mold is connected to an inlet system. The mold is designed to produce hollow castings having a metal thickness of approx. 3.5 mm on all sides. The molding is provided at one end with an opening for removing the core therefrom.

Melted aluminum with a temperature of approx. 705 ° C made from aluminum bars is poured into the mold. After cooling for approx.

For 1 hour, the aluminum moldings are broken from the inlet system and removed from the mold for shaking examination.

The shaking test is carried out by placing a casting blank 25 in a container with a volume of approx. 3.8 liters. The container is placed on a shaking mechanism and shaken for 2 minutes. The weight of the sand core removed from the cast in this way is compared to the initial weight of the sand core and the shaking is calculated as a percentage. The sand remaining in mold 30 after shaking as described above is removed by scraping * and also weighed. The sand core bonded with the above-described phenolic resin polyisocyanate binder is not shaken out after the shaking. The outbreak is 0%. By comparing this example with the previous examples, the advantage gained from the shaking is seen by using an amine polyol in a cold-box system compared to other polyols used in a cold-box system, when casting at low temperatures.

Claims (2)

A method of casting lightweight metal articles which are formed using non-heat cured urethane binder containing moldings which crumble in 5 castings after casting the metal articles, characterized in that J ψ (a) forms a casting applying a non-thermosetting binder composition in a binding amount of up to 10%, based on the weight of the aggregate, 10 wherein the composition contains a mixture of a polyol component comprising an amine polyol; a liquid polyisocyanate component; and a catalyst for urethane formation, (b) forming the molding mixture to the desired molding article, (c) letting the mixture cure after the desired molding article has been formed, (d) heating the lightweight metal until it melts and castable, (e) ) molds the lightweight metal using the molded molding article, (f) solidifies the cast metal, and (g) causes the molding article to crumble and removes the crumbed molding article from the molded lightweight metal article. ft 25 Process according to claim 1, characterized in that the amine polyol comprises an aromatic amine polyol.