CH647965A5 - METHOD FOR CASTING LIGHT METALS. - Google Patents

Description

The present invention relates to a method for casting light metals using foundry articles which disintegrate after casting or are brought to decay using foundry articles which are produced with the aid of mixtures of aminopolyols and polyisocyanates and hardened with a gaseous catalyst can. Such binders of the named “no bake” and of the “cold box” type, which contain an aminopolyol, are capable of binding sand or other foundry additives to form molds or cores for metal casting, in particular for casting aluminum and others To form light metals, which are cast at relatively low temperatures. The cores and shapes made using these binders have significantly improved disintegration or

Pourability when used at low foundry temperatures.

Cold box urethane binders for use in binding aggregates which are useful as foundry cores and molds are already known. US Patent 3,409,579 describes an example of such a "cold box" binder and its use in the manufacture of cores and molds for the foundry.

A «cold box» binder system for the foundry, which contains an aminopolyol as a component of the binder, is in itself an advance in the field of foundry binders.

Furthermore, "no bake" urethane binders for use in binding aggregates useful as foundry cores and molds have also been described. For example, US Pat. No. 3,676,392 describes a "no bake" binder and its use in the manufacture of cores and molds for the foundry.

There has long been a need in the foundry industry for a "no bake" and a "cold box" binder for the production of light metal castings, such as Aluminum and magnesium castings. The previously known "no bake" and "cold box" binders were not able to supply cores and molds for the casting of these light metals, which contained the required core and mold properties. If sufficient binder is used to provide satisfactory strength and abrasion resistance, the cores and molds will not disintegrate well at the casting temperatures used for light metals. they result in poor distributability. There was therefore a need for a binder which, on the one hand, gave strong, non-brittle cores and shapes and, on the other hand, disintegrated well at the casting temperatures used for aluminum and magnesium in order to enable easy removal.

The inventive method for casting light metals is defined in claim 1.

An important advance is the use of urethane "no bake" and "cold box" binders to produce cores and shapes that have strength and non-brittleness, but disintegrate at low casting temperatures, i.e. below the casting temperatures of ferrous metals. The cores and molds used according to the invention have the combination of strength and easy shaking out at casting temperatures of light metals, such as aluminum and magnesium.

It has been found that a urethane binder, which is formed as a reaction product of a polymeric isocyanate and an amine-based polyol, can be used to make cores and molds. The binder can be quickly cured using a gaseous tertiary amine as a catalyst. It has been found that a polyol, which is the reaction product of an amino compound and an alkylene oxide, can be combined with a polymeric isocyanate to produce a "no bake" or a "cold box" binder which, after mixing with sand or other suitable cast irritation aggregate and hardening forms cores and shapes which have excellent properties, namely strength, abrasion resistance and non-brittleness. These properties are coupled with excellent shaking properties when the products are used in the casting of non-ferrous metals. This combination of good working properties and excellent shaking properties are particularly significant and unique when the binder is used to make cores that are intended for use in low temperature casting. A catalyst can be used5

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to harden the components of the binder system. Suitable catalysts for the "cold box" process are gaseous tertiary amines or amines, which can be introduced as steam. Trimethylamine, dimethylethylamine and triethylamine are the preferred catalysts. A catalyst is not necessarily a component of the "no bake" binder systems. Suitable catalysts can, however, also be used in the “no bake” binder and are preferred with certain aminopolyols if rapid curing is required.

The resin compositions are used as two-component compositions or systems. The first component is the aminopolyol. The second component is the polyisocyanate. Both components are in liquid form and are usually present as solutions in organic solvents. At the time of use, i.e. when the urethane binder is formed, the aminopolyol component and the polyisocyanate component are combined and used for the desired application. In the foundry, i.e. when using the compositions as binders for cores and molds, it is preferred to first add a component with a foundry additive, e.g. B. sand to mix. The second component is then added, and after the binder has been uniformly distributed over the additive, the foundry molding composition obtained is shaped into the desired shape. The molded product can be placed immediately on the side and cures to form a core or shape at room temperature. The compositions are generally autocatalytic to some extent. That is, once the aminopolyol and the isocyanate are combined, the reactivity of the polyol with the isocyanate is such that the reaction proceeds quickly enough not to require a catalyst. The degree of reactivity of the aminopolyol and the polyisocyanate depends on the reactivity of the polyol. The molded product can also be cured into a core or mold by contacting it with a gaseous catalyst.

Despite the fact that the compositions are autocatalytic, liquid aminocatalysts and metallic catalysts, as are known in urethane technology, can be used in the "no bake" embodiment. It should be noted that in certain cases the use of a catalyst with the aminopolyol and polyisocyanate components is useful and preferred. By choosing an appropriate catalyst, the conditions of the core manufacturing process, e.g. the processing time and the stripping time can be adjusted as desired. In practice it may be necessary to use a catalyst with certain polyols in order to achieve the desired production speeds.

Gaseous amines, which are known as catalysts in cold box technology, can also be used. The actual curing step can be carried out by suspending a tertiary amine in an inert gas stream and passing the gas stream containing the tertiary amine through the mold under sufficient pressure to penetrate the molded mass until the resin is cured. The binder compositions used according to the invention require extraordinarily short curing times in order to achieve acceptable tensile strength, which is of the greatest economic importance. The optimal curing times can easily be determined experimentally. Since the tertiary amine is only required in a catalytic concentration to produce the hardening, a very dilute stream is generally sufficient to achieve the hardening. However, excess concentrations of the tertiary amine above the amount required to produce the curing are in no way harmful to the cured product obtained. Inert gas flows, e.g. Air, carbon dioxide or nitrogen containing from 0.01 to 20 volume percent tertiary amine can be used. Gaseous tertiary amines can usually be passed through the mold either as such or in dilute form. Suitable tertiary amines are tertiary amines, such as trimethylamine. However, normally liquid tertiary amines, such as triethylamine, are also suitable in volatile form or when suspended in a gaseous medium and then passed through the mold. Although ammonia, primary amines and secondary amines have some effectiveness in initiating a reaction at room temperature, they are significantly less effective than the tertiary amines. Functionally substituted amines, such as dimethylethanolamine, are included in the term tertiary amines and can also be used as curing agents. Functional groups that do not interfere with the action of the tertiary amine are hydroxyl groups, alkoxy groups, amino and alkyl amino groups, ketoxy groups, thio group and the like.

The amino polyols used to form the urethane binder compositions are typically produced as a reaction product of an alkylene oxide and an amino compound. When the term "aminopolyol" is used here, it means such reaction products,

without, however, being restricted specifically to this type of production. In general, any polyol that contains at least one tertiary amino group is included in the definition of an “aminopolyol”. The alkylene oxides which can be used to prepare the aminopolyols are preferably ethylene oxide and propylene oxide. However, other alkylene oxides can also be used. The molar ratio of alkylene oxide to amino compound can be varied considerably. The degree of alkoxylation is believed to be unrelated to the ability of the resulting aminopolyol to act as a binder.

The amino compounds which react with alkylene oxide to form the amino polyols useful for the binder compositions include ammonia and mono- and polyamino compounds containing primary and secondary amino nitrogen. Specific examples include aliphatic amines such as primary alkyl amines, ethylene diamine, diethylene triamine and triethylene tetramine, cycloaliphatic amines, aromatic amines such as ortho-, meta- and para-phenylenediamines, aniline formaldehyde resins and the like. Mixtures of the above aminopolyols can also be used. In addition, a mixture of aminopolyols with other polyols, e.g. B. non-amine polyols can be used. In general, compounds containing amino groups which, when alkoxylated, give a polyol having two or more reactive hydroxyl groups are believed to be useful for the purposes of the present invention.

The nature of the polyol component used affects the conditions of the core manufacturing process. In a "cold box" process, i.e. In a process in which the resin-coated sand is hardened by gassing with an amine as a catalyst, the "table time" is an important property of the binder. The table time, which corresponds to the processing time in a "no bake" system, is the time during which the sand coated with resin can be processed. After a binder is spread over the aggregate,

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the binder begins to react. After a certain period of time, the reaction has progressed to such an extent that the sand coated with resin can no longer be used. The sand coated with the binding agent is then referred to as “shot”. After the sand has been coated with the resin, the time until the sand mixture is “shot” is called “table time” in a “cold box” system. It has been found that the use of an aromatically infected aminopolyol leads to an unexpected increase in the table time of the resin-coated sand. This unexpected result is of great value and is considered important.

As mentioned above, it has been found that mixing an aminopolyol with another polyol, a polyhydroxy compound that is capable of reacting with the polyisocyanate, has been found to be useful. This usefulness is particularly evident in the strengths which are achieved after the binder has been subjected to the influence of the catalyst. Particularly preferred are phenolic resins containing hydroxy groups, as described in US Pat. No. 3,485,797 and known in the foundry industry as "PEP" resins.

The second component of the binder composition used contains an aliphatic, cycloaliphatic or aromatic polyisocyanate, which preferably contains 2 to 5 isocyanate groups. If desired, mixtures of polyisocyanates can be used. Isocyanate prepolymers which are formed by reacting excess polyisocyanate with a 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 4,4'-dicyclohexylmethane diisocyanates, and aromatic polyisocyanates such as 2,4- and 2,6-toluenediisocyanate, diphenylmethane diisocyanate and dimethyl derivatives thereof. Other examples of suitable polyisocyanates are 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate, xylylenediisocyanate and the methyl derivatives thereof, polymethylene polyphenyl isocyanates and their methyl derivatives, chlorophenylene-2,4-diisocyanate and the like. Although all of the polyisocyanates react with the aminopolyol to form a cross-linked polymer structure, the preferred polyisocyanates are aromatic polyisocyanates, and especially diphenylmethane diisocyanate, triphenylmethane triisocyanate, and mixtures thereof.

The polyisocyanate is usually used in approximately stoichiometric amounts, i.e. in sufficient concentration to cause the aminopolyol to cure. However, it is easily possible to deviate from this amount within certain limits, and in certain cases this can result in advantages. Generally, the polyisocyanate is used in an amount of 10 to 500 percent by weight based on the weight of the aminopolyol. Preferably 20 to 300 percent by weight of the polyisocyanate, calculated on the same basis, is used. The polyisocyanate is used in liquid form. Liquid polyisocyanates can be used in undiluted form. Solid or viscous polyisocyanates are generally used in the form of solutions in an organic solvent, the solvent generally being present in an amount up to 80 percent by weight of the solution.

Although the solvent used with either the aminopolyol or the polyisocyanate or both components does not participate in any significant degree in the reaction between the isocyanate and the aminopolyol, it can interfere with the reaction. The difference in polarity between the polyisocyanate and the aminopolyol limits the choice of solvents in which both components are compatible. This compatibility is necessary in order to achieve a complete reaction and the curing of the binder compositions. Polar solvents, both protic and aprotic, are good solvents for the aminopolyol. It is therefore preferred to use solvents or combinations of solvents that are compatible with the polyol and polyisocyanate when mixed. In addition to compatibility, the solvents for either the polyol or the polyisocyanate are advantageously selected so that they result in 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 solvent mixtures which have a high content of aromatic compounds and have a boiling point in the range from 137 to 385 ° C. The polar solvents should not be extremely polar so that they become incompatible when used with the aromatic solvents. Suitable polar solvents are generally those referred to in the art as "coupling solvents" and include, for example, furfural, cellosolve, glycol diacetate, butyl cellosolve acetate, isophorone and the like. It is also possible to use certain reactive polyols as solvents. It should also be noted that water has proven to be a suitable solvent for the aminopolyol under certain conditions.

The binder components are combined and then mixed with sand or a similar foundry additive to form the foundry molding compound, or the foundry molding compound can also be formed by successively adding the components to the additive. Methods for distributing the binder on the aggregate particles are well known to those skilled in the art. The foundry molding compound may also contain other constituents, such as Iron oxide, ground shag fibers, wood cereals, tar, heat-resistant flours and the like. The aggregate, e.g. Sand, is commonly used as the main ingredient and the binder content is a relatively small proportion. Although the sand is preferably used as dry sand, a certain level of moisture can be tolerated. This is especially true when the solvent used is immiscible with water or when an excess of polyisocyanate required for curing is used, since such an excess of polyisocyanate reacts with the water and water is a useful solvent for the aminopolyol.

As already mentioned, the excellent shaking or disintegrating ability of the cores and shapes produced using the binders described above is considered essential. The binders used according to the invention disintegrate easily and thereby enable the core or the mold to be separated from the casting. For casting at low temperatures, e.g. at around 980 ° C (1800 ° F) or below, shaking has been a major difficulty. Typically, non-ferrous metals, including aluminum and magnesium, are cast at such temperatures. The inability of the binder to disintegrate leads to great difficulty in removing the sand from the casting. Cores with a low degree of shaking or disintegration, i.e. a low level of binder breakdown, therefore require more time and energy to remove the sand from the casting. The use of the above be4

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The binder compositions described in many cases lead to 100% shaking out without the use of any external energy. The improvement in the shaking ability is due to the presence of the aminopolyol in the binder composition. It will be apparent to those skilled in the art that the ability of each core to be shaken 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 required for the binder system. As the amount of binder in the system increases, the tensile strength of the core or shape usually also increases. The binder content can thus be varied within 15 reasonable limits to achieve the desired properties of the core or shape. A preferred amount of binder is between 0.7% and 2.5%, calculated on the weight of the additive. However, it is easily possible to use only 0.5% and up to 10% binder and still achieve properties that are advantageous for certain applications. However, it has been found that when the amount of binder is increased, the degree of shaking out can decrease with higher binder contents.

The present invention is explained in more detail below with the aid of a few examples, in which, unless stated otherwise, all parts are parts by weight and all percentages are percentages by weight.

example 1

An aminopolyol was prepared by propoxylating 1.0 mole of ethylenediamine with 4.2 moles of propylene oxide. A solution containing 40% solids of the aminopolyol was prepared by dissolving the polyol in an aromatic solvent, which is commercially available under the trademark "HISOL" 10. This solution is referred to below as Part I. A solution of a polymeric isocyanate with a solids content of 75%, based on “Mon-dur MR”, which is commercially available from Mobay, was produced using an aromatic solvent, namely also “HISOL” 10. The isocyanate solution is referred to below as Part II.

"Wedron 5010" sand (washed and dried, fine-grained silicon oxide sand, AFSGFN 66) was placed in a suitable mixing device. Part I was mixed with the sand until a uniform coating was achieved.

Part II was then added to and mixed with the coated sand until a homogeneous sand mixture was formed. An almost stoichiometric amount of polyisocyanate, a slight excess, was used to fully react with the hydroxyl groups of the polyol. 1.5% of the total binder (equal parts of Part I and Part II) based on the weight of the sand was used.

The mixture of sand, polyol and polyisocyanate was placed in a core molding box and standard draft briquettes, known as "dog bones", were made. A processing time of 5 minutes and a stripping time of 8 minutes were achieved. The tensile strength after 2 hours and 4 hours and 24 hours was 21, 26 and 27 kg / cm2 (300, 371 and 387 psi).

The "dog bone" cores were used in studies on the shaking out of aluminum castings. Seven "dog bones" were placed in a mold. The mold contained a sprue system. The mold was constructed in such a way that it produced hollow castings with a wall thickness of approximately 6.35 mm on all sides. An opening was made at one end of the casting to allow the core to be removed from the casting. Molten aluminum at about 704 ° C (1300 ° F) made from aluminum ingot was poured into the mold. After cooling for about 1 hour, the aluminum castings were broken off from the start-up system and removed from the mold in order to investigate the shaking out.

The shake tests were performed by placing a casting in a 3.785 liter (1 gallon) container. The container was placed on a shaker and tumbled for 2 minutes. The weight of the sand core which is removed from the casting in this way is compared with the original weight of the sand core and the percentage of the shaken out core material is calculated. Sand that remains in the casting after this treatment is removed by scraping and also weighed. The sand core, which had been bound with the aminopolyol-polyiso-cyanate binder described above, disintegrated and ran out of the aluminum casting without using the shaker and without using any external mechanical energy. The shaken out portion was 100%.

Examples 2 to 6

Using the procedure described in Example 1, "dog bone" test cores were made using the components and methods listed below. The cores were used to carry out the shaking tests using an aluminum casting as described in Example 1.

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Example 2

Example 3

Example 4

Example 5

Example 6

sand

Amino compound

Alkylene oxide (AO) molar ratio of AO-amine aminopolyol

Polyisocyanate solvent for aminopolyol

Solvent for polyisocyanate catalyst

"Wedron" 5010

Diethylene

triamine

Propylene oxide

5.1: 1

"Mondur" MR 40%

«HISOL» 10 no none

"Wedron" 5010 tetramine

Triethanol amine from «UPJOHN» 3 «Mondur» MR 10%

«ISOPHORON» no no

"Wedron" 5010

Triethylene

tetramine

Propylene oxide

6.2: 1

"Wedron" 5010 ethylenediamine propylene oxide 12: 1

"Mondur" MR 60%

"ISOPHORON"

25%

«HISOL» 10 no

"Mondur" MR 60%

"HISOL" 10 25%

«HISOL» 10 no

"Wedron" 5010

"QUADROL" b

"Mondur" MR 60%

"HISOL" 10 25%

«HISOL» 10 no

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6

Example 2

Example 3

Example 4

Example 5

Example 6

Processing time

5 min.

2 min.

0.5 min.

6 min.

5 min.

Stripping time

12 min

4.5 min.

1.0 min.

9 min.

8 min.

% Binder

1.5%

1.5%

1.5%

1.5%

1.5%

40% T.I.

50% T.I.

60% T.I.

50% T.I.

50% T.I.

60% T.II

60% T.II

40% T.II

50% T.n.

50% T.II

Tensile strength in kg / cm2

2 hours

7

10.71

5.95

25.2

23.73

4 hours

8.26

14.70

7.91

25.55

24.50

24 hours

11.41

17.30

16.1

26.81

Shaken out core material

100%

100%

Ì 00%

100%

100%

a "UPJOHN" is a brand for triethanolamine, i.e. ethoxylated ammonia, commercially available from Upjohn Corporation. b "QUADROL" is the brand name for propoxylated ethylenediamine in a molar ratio of 4: 1, commercially available from BASF Wyan-

dotte.

T. I = Part I T. II = Part II

Cores that were made as described above disintegrated and the material poured onto the casting without the use of a shaker or application of any external mechanical energy.

Example 7

An aromatic aminopolyol was prepared by propoxylating 1 mole of meta-phenylenediamine with 4.2 moles of propylene oxide. A solution (40% solids content) of the aromatic aminopolyol obtained was prepared by dissolving the polyol in an aliphatic solvent, namely butyl cellosolve. This solution is referred to below as Part I. A 75% solids polymer isocyanate solution based on "Mondur" MR (commercially available from Mobay) was prepared using an aromatic solvent that is commercially available under the "HISOL" 10 brand. This isocyanate solution is referred to below as Part II. The amount of polyisocyanate used was approximately the stoichiometric amount required to fully react with the hydroxyl group of the polyol.

"Wedron" 5010 sand (washed and dried fine-grain quartz sand AFSGFN 66) was placed in a mixing device. Part I was mixed with the sand until a uniform coating was formed. Part I also contained a urethane catalyst, namely triethylene diamine, which is commercially available under the "DABCO" brand. This catalyst is a well-known urethane catalyst. It was used in an amount of 0.8% by weight of Part I. Part II was then added to and mixed with the coated sand until a homogeneous sand mixture was formed. 1.5% binder (Part I and Part II together) based on the weight of the sand was used.

The mixture of sand, polyol, catalyst and polyisocyanate was then placed in a core mold box and "dog bones" were made. A workability time of 70 minutes and a stripping time of 110 minutes were obtained. The tensile strength after 24 hours was 15.1 kg / cm2.

The "dog bone" cores were used to make the

To be examined with aluminum castings. Seven "dog bones" were arranged in a form. The mold contained a sprue system. The mold was constructed in such a way that hollow castings with a metal thickness of 6.25 mm were formed on all sides. An opening was made at one end of the casting 30 to remove the core from the casting. Molten aluminum at about 704 ° C, made from aluminum bars, was poured into the mold. After cooling for about 1 hour, the aluminum castings were broken off from the start-up system and removed from the mold in order to examine whether they could be shaken out.

The shaking test was carried out by placing the castings in a 3.785 liter container. The container was placed on an agitation device and tumbled for 2 minutes. The weight of the sand core, which was removed from the casting in this way, was compared with the original weight of the sand core and the percentage of the material distributed was calculated. Sand that remained in the casting after the treatment described above was removed by scraping and also weighed. The sand core, which had been bound with the aminopolyol-polyisocyanate catalyst binder described above, disintegrated and ran out of the aluminum casting without using the agitation device and without using any external mechanical energy. The shaken out portion was 100%.

Examples 8 to 11 Using the procedure described in Example 7, "dog bone" test cores were made using the components and methods described below. The cores were used in shake tests using aluminum castings as described in Example 7.

Example 8 Example 9 Example 10 Example 11

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

Amine component

Alkylene oxide

AO: amine molar ratio

Aminopolyol "PluracoF 767" "PluracoP 767" "Pluracold 795" "Pluracold 796"

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Example 8

Example 9

Example 10

Example 11

Polyisocyanate

"Mondur" MR

"Mondur" MR

"Mondur" MR

"Mondur" MR

Aminopolyol solvent

40% «HISOL» 10

35% water

35% «HISOL» 10

35% «HISOL» 10

Solvent for polyisocyanate

44% e no

35% e

35% e

Catalyst (1)

1.4%

no no

(1) 1.5%

Processing time

25 min.

10 min.

11.5 min.

7 min.

Stripping time

31 min.

16 min.

16 min.

10.5 min.

% Binder

1.5%

1.7%

1.5%

1.5%

part One

50%

60%

50%

50%

Part II

50%

40%

50%

50%

Tensile strength in kg / cm2

2 hours

15.75

7.56

14.21

(3 hrs) 22.61

4 hours

-

8.96 (3 hours)

14.91

7.7

24 hours

25.76

-

22.61

22.4

Shaken out core material

92%

100%

100%

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

c “Pluracol 767” is a brand name for a propoxylated aromatic aminopolyol, commercially available from BASF Wyandotte. d "Pluracol 795" is a trademark for an ethoxylated aromatic aminopolyol, commercially available from BASF Wyandotte.

e a mixture of «HISOL» 10 and kerosene.

Cores, which had been produced as described above, disintegrated and leaked out of the castings, without using an agitation device and without using any external mechanical energy.

Example 12

An aromatic aminopolyol was prepared by propoxylating 1 mole of ortho-phenylenediamine with 4.2 moles of propylene oxide. A 40% solids solution of the aromatic aminopolyol was prepared by dissolving the polyol in isophorone. This solution is referred to below as Part I. A polymeric isocyanate, “Mondur” MR, is referred to as Part II. An amount of polyisocyanate was used which approximately corresponded to the stoichiometric amount required for complete reaction with the hydroxyl groups of the polyol.

"Wedron" 5010 sand (washed and dried fine-grained quartz sand, AFSGFN 66) was filled into a mixing device. Part I was mixed with the sand until a uniform coating was achieved. Part I also included a 33% solution of an ure thank catalyst, namely triethylenediamine, in dipropylene glycol, commercially available under the brand name “DABCO”. This catalyst is a well-known urethane catalyst. 0.1% of the catalyst by weight of Part I was used. Part II was then added to and mixed with the coated sand until a homogeneous sand mixture was formed. A total of 1.5% binder (55% Part I and 45% Part II) based on the weight of the sand was used.

The mixture of sand, polyol, catalyst and polyisocyanate was placed in a core mold box and “dog bones” were made. A workability of 9 minutes and a stripping time of 20 minutes were achieved. The tensile strength after 2 hours and 24 hours was 20.44 kg / cm2 and 21.91 kg / cm2, respectively.

The «dog bone» cores were used in shaking tests with aluminum castings. seven

"Dog bones" were arranged in a form. The mold was equipped with a sprue system. The shape was designed in such a way that hollow castings with a metal thickness of 6.25 mm were created on all sides. An opening was made at one end of the casting to remove the core from the casting. Molten aluminum at about 704 ° C, made from aluminum bars, was poured into the mold. After cooling for about 1 hour, the aluminum castings were broken off from the start-up system and removed from the mold in order to examine the ability to shake out.

The shaking tests are carried out by placing a casting in a 3.785 liter container. The container is placed on a shaker and tumbled for 2 minutes. The weight of the sand core, which is removed from the casting in this way, is compared with the original weight of the sand core and the percentage of the pouring is calculated. The sand remaining in the casting after the treatment described is removed by scraping and also weighed. The sand bound with the aminopolyol polyisocyanate catalyst binder described above disintegrated and poured out of the aluminum casting without using the shaker and without using any external mechanical energy. The shaking was 100%.

Examples 13 to 15

Using the procedure described in Example 12, "dog bone" test cores were made using the components and methods described below. The cores were used in shake tests using aluminum castings as described in Example 12.

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Example 13

Example 14

Example 15

sand

Amine compound

"Wedron" 5010

meta-phenylenedi-

amine

"Wedron" 5010 "UCRITHANE103" an aniline formaldehyde resin from Upjohn

"Wedron" 5010 aniline

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Example 13

Example 14

Example 15

Alkylene oxide

Propylene oxide

Propylene oxide

Propylene oxide

AO: amine molar ratio

4.2: 1

4.2: 1

2.2: 1

Aminopolyol

Polyisocyanate

"Mondur" MR

"Mondur" MR

"Mondur" MR

Aminopolyol solvent

60% isophorone

60% isophorone

60% (X)

Solvent for polyisocyanate no no no

Catalyst no no

1% «Dabco»

Processing time

45 min

70 min

70 min

Stripping time

78 min.

101 min

140 min

% Binder

1.5%

1.5%

1.5%

part One

55%

73%

61%

Part II

45%

27%

39%

Tensile strength in kg / cm2

2 hours

10.15

1.54

4 hours

21.49

9.8

24 hours

22.4

9.8

12.6

Shaken out core material

89%

100%

74%

(X) A mixture of butyl cellosolve acetate (40%) and «Hisol» 10 (20%).

Cores made as described above disintegrated and ran out of the casting using an agitation device and using external mechanical energy.

Example 16

An aminopolyol was prepared by propoxylation of 1.0 mole of meta-phenylenediamine with 6.0 mole of propylene oxide. A 40% solids solution was prepared by dissolving the polyol in a mixture of 40% isophorone, 1.6.5% aromatic solvent and 3.5% kerosene. The solution is referred to below as Part I. A 75% solids polymeric isocyanate solution based on "Mondur" MR, commercially available from Mobay, was prepared using an aromatic solvent "HISOL" 10. The isocyanate solution is hereinafter referred to as Part II. The amount of polyisocyanate used approximately corresponded to the stoichiometric amount required for complete reaction with the hydroxyl groups of the polyol.

»Wedron» 5010 sand (washed and dried fine-grained quartz sand, AFSGFN 66) was placed in a mixing device. Part I was mixed with the sand until an even conviction was formed. Part II was added to and mixed with the coated sand until a homogeneous sand mixture was formed. A total of 1.5% of the binder (equal amounts of Part I and Part II) was used based on the weight of the sand.

The mixture of sand, polyol and polyisocyanate was blown into a conventional core cavity or box for the production of standard tensile briquette test cores known as "dog bones". The «dog bone» test cores were hardened by exposing the cores to a tertiary amino catalyst. This catalyst, dimethylethylamine, was suspended in carbon dioxide as an inert carrier gas. The cores were exposed to the amine catalyst for about 20 seconds (fumigation time) and then left in the mold box for 10 minutes before the core was removed from the box. The tensile strength in kg / cm2 was 1.75 immediately after removal from the box, 5.04 after 1 hour and 9.45 after 24 hours.

The «dog bone» cores were used in shaking tests with aluminum castings. Seven 35 "dog bones" were arranged in a mold. The mold was equipped with a sprue system. The shape is intended to form hollow castings with a metal thickness of approximately 6.25 mm on all sides. An opening is made at one end of the casting for removing the core from the casting. Molten aluminum at about 704 ° C, made from aluminum bars, was poured into the mold. After cooling for about 1 hour, the aluminum castings were broken off the sprue system and removed from the mold 45 to test shaking. The shaking tests are carried out by placing a casting in a 3.785 liter container. The container is placed on a shaker and tumbled for 2 minutes. The weight of the sand core, which is removed from the casting in this way, is compared with the original weight of the sand core and the percentage shaking is calculated. The sand remaining in the casting after this treatment is removed by scraping and also weighed. The 55 sand core, which had been bound with the aminopoly-ol polyisocyanate binder described above, disintegrated and ran out of the aluminum piece, without using the shaking device and without using any external mechanical energy. The shaking was 60 100%.

Examples 17 to 21 Using the method described in Example 16, puddle cores with the following components 65 were produced and examined.

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647 965

Example 17

Example 18

Example 19

Example 20

Example 21

sand

"Wedron" 5010

"Wedron" 5010

"Wedron" 5010

"Wedron" 5010

"Wedron" 5010

Amine compound

Aniline ortho-phhe

meta-phe-

meta-phe-

«CURITHANE

nylene nylene nylene diamine

103 », an aniline formaldehyde resin from Upjohn

Alkylene oxide

Propylene oxide

Propylene oxide

Propylene oxide

Propylene oxide

Propylene oxide

AO: amine molar ratio

2: 1

4.2: 1

4.2: 1

8: 1

4: 1

Aminopolyol

Polyisocyanate

"Mondur" MR

"Mondur" MR

"Mondur" MR

"Mondur" MR

"Mondur" MR

Amino solvent

60% (1)

60% isophorone

60% isophorone

60% (1)

60% isophorone polyol

Solvent for poly no

25% (2)

25%

25% (2)

no isocyanate

"MISOL" 10

catalyst

Trimethyl

Dimethyl

Dimethyl

Dimethyl

Trimethylamine

amine

ethylamine suspended in C02

ethylamine suspended in C02

ethylamine suspended in C02

Fumigation time

10 sec

10 sec

10 sec

20 sec

5 sec

Service life

5 min.

3 min.

10 min.

10 min.

2 min.

Tensile strength kg / cm2

when leaving the box

2.1

3.5

0.35

7.35

2.1

1 hour

7.0

4.55

7.35

24 hours

6.3

5.95

7.91

totally binder

1.5%

1.5%

1.5%

1.5%

1.5%

part One

75%

50%

50%

50%

75%

Part II

25%

50%

50%

50%

25%

shaken out core material

100%

100%

100%

100%

100%

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

(2) A mixture of an aromatic solvent, which is commercially available under the name "Texaco Solvent" 7545 (19%) and kerosene (6%).

Cores, which were produced as described above, disintegrated and leaked out of the casting without using a shaking device and without using any external mechanical energy. 40

Example 22

An aminopolyol was prepared by propoxylating 1.0 mole of methaphenylenediamine with 8.0 mole of propylene oxide. A phenolic polyol, commercially available as 45 "PEP" resin, was added to the aminopolyol to form a polyol blend. The ratio of o-aminopolyol to non-aminopolyol was 2: 1. A 60% solids solution of the polyol mixture was prepared by dissolving the polyol mixture in isophorone solvent. 50 This solution is referred to below as Part I. A 75% solids solution of a polymeric isocyanate based on "Mondur" MR, commercially available from Mobay, was prepared using a mixed solvent consisting of 19% "Texaco 7545", 55 an aromatic solvent, and 6% Kerosene. The isocyanate solution is referred to as Part II. The amount of polyisocyanate approximately corresponded to the stoichiometric amount required for complete reaction with the hydroxyl groups of the polyol. 60

"Wedron" 5010 sand (washed and dried fine-grained quartz sand, AFSGN 66) was filled into a mixing device. Part I was mixed with the sand until a uniform coating was created. Part II was added to and mixed with the coated sand until a homogeneous sand mixture was formed. 1.5% of total binder (44% Part I and 56% Part II) was used based on the weight of the sand.

The mixture of sand, polyol and polyisocyanate was blown into a conventional core cavity or a box for the production of "dog bones". The «dog bone» test cores were hardened by exposure to a tertiary amine as a catalyst. The catalyst, dimethylethylamine, was suspended in carbon dioxide, an inert carrier gas. The cores were exposed to the catalyst for about 5 seconds (fumigation time) and left in the core box for about 1 minute before being removed from the box. The tensile strength was 4.06 kg / cm2 immediately upon leaving the box and 14 kg / cm2 after 1 hour and 14.7 kg / cm2 at the time of casting.

The «dog bone» cores were used in shaking tests with aluminum castings. Seven "dog bones" were arranged in a form. The mold was provided with a start-up system. The mold was designed to produce hollow castings with a metal thickness of approximately 6.25 mm on all sides. An opening was made at one end of the casting to remove the core from the casting. Molten aluminum at about 704 ° C made from aluminum ingot was poured into the mold. After cooling for about 1 hour, the castings were broken off from the start system and removed from the mold for inspection of the shakers.

Distribution tests are carried out by placing a casting in a 3.785 liter container. The container is placed on a shaker and shaken for 2 minutes. The weight of the sand core thus removed on the casting is compared to the original weight of the sand core and

647 965

10th

the percentage shaking is calculated. Sand that remains in the casting after this treatment is removed by scraping and also weighed. The sand core, which had been bound with the aminopolyol-polyiso-cyanate binder described above, disintegrated and ran out on the aluminum casting without using the shaker and without using any external mechanical energy. The shaking was 100%.

Examples 23 and 24

sand

"Wedron" 5010

"Wedron" 5010

Amino compound

"Curithan" 103

Alkylene oxide

Propylene oxide

Molar ratio of alkylene oxide:

-

Amine

Aminopolyol

"Pluracol" 7351

amine-free polyol phenolic polyol phenolic polyol

Amino polyol ratio:

2: 1

2: 1

amine-free polyol

Polyisocyanate

"Mondur" MR

Solvent for polyol mixture

40% butyl cellosolve acetate

40% butyl cellosolve acetate

Solvent for polyisocyanate

25% aromatic «Solvent 7545»,

5% kerosene

25% kerosene

catalyst

Trimethylamine

Trimethylamine

Fumigation time

5 sec

5 sec

Service life

1 min.

1 min.

Tensile strength in kg / cm2

3.15

3.64

8.89 (1 h)

8.75 (1 h)

7.7 (4 hrs)

8.89 (when casting)

11.34 (when casting)

total binder r / 2%

l '/ 2%

Part

44%

50%

Part II

56%

50%

Shaking

100%

48%

An amine based on polyol from BASF (probably ethoxylated and aromatic).

The sand core, which had been bound with the aminopolyol, which had been derived by propoxylation of "Curitha-ne 103", an aniline formaldehyde resin from Upjohn, disintegrated and ran out of the aluminum casting without using the agitation device and without using external energy. The sand core based on «Pluracol 735» was poured in order to maintain the specified degree of shaking.

Example 25

An aminopolyol was prepared by propoxylating 1.0 mole of ethylenediamine with 8.0 moles of propylene oxide. A 50% solids solution of the aminopolyol was prepared by dissolving the polyol in a mixture of 30% isophorone, 16.5% aromatic solvent and 3.5% kerosene. This solution is referred to below as Part I. A 75% solids polymeric isocyanate solution based on "Mondur" MR, commercially available from Mobay, was prepared using an aromatic solvent, "Texaco 7545" (19%) and kerosene (6%). The Isocyanate solution is referred to below as Part II. The amount of polyisocyanate used approximately corresponded to the stoichiometric amount required for complete reaction with the hydroxyl groups of the polyol.

"Wedron" 5010 sand (washed and dried fine-grained quartz sand, AFSGFN 66) was placed in a mixing device. Part I was mixed with the sand until a uniform coating was created. Part II was added to the coated sand and mixed until a homogeneous sand mixture was obtained. 1.5% binder (equal parts of Part I and Part II) based on the weight of the sand was used.

The mixture of sand, polyol and polyisocyanate was blown into a standard core cavity or box for the production of standard test cores known as "dog bones". The «dog bone» test cores were hardened by being exposed to a tertiary amine, namely trimethylamine as a catalyst. The cores were exposed to the amine catalyst for about 10 seconds (fumigation time) and left in the core box for 5 minutes before being removed from the box. The tensile strength was 5.6 kg / cm2 15 minutes after fumigation and 9.45 kg / cm2 after 24 hours. The "dog bone" cores were used in shaking tests with aluminum castings. Seven "dog bones" were arranged in a form. The mold was equipped with a sprue system. The mold was designed for the production of hollow castings with a metal thickness of approximately 6.25 mm on all sides. An opening was made at one end of the casting to remove the core from the casting. Molten aluminum at about 704 ° C, made from aluminum bars, was poured into the mold. After cooling 60 for about 1 hour, the aluminum castings were broken off the sprue system and removed from the mold to perform the shake tests.

Shaking tests are performed by placing a casting in a 3.785 liter container 65. The container is placed on a shaker and shaken for 2 minutes. The weight of the sand core thus removed from the casting is compared to the original weight of the sand core

il

647 965

and calculated the percentage shaking. Sand that remains in the casting after this treatment is scraped off and also weighed. The sand core, which was bound with the aminopolyol-polyisocyanate binder described above, disintegrated and ran out of the aluminum casting without using the shaker and without using any external mechanical energy. The shaking was 100%.

Example 26

A 58.5% solids solution of a phenolic polyol, commercially available as "PEP" resin, was prepared by dissolving the "HISOL" 10 polyol. This solution is referred to below as Part I. A solution of a polymeric isocyanate with 75% solids content, based on "Mondur" MR, commercially available from Mo-bay, was prepared using a solvent mixture consisting of 10% "Texaco 7545", an aromatic solvent, and 6% Kerosene existed. The Isocyanate solution is referred to below as Part II. The amount of polyisocyanate used approximately corresponded to the stoichiometric amount required for complete reaction with the hydroxyl groups of the polyol.

"Wedron" 5010 sand (washed and dried fine-grained quartz sand, AFSGEN 66) was placed in a mixing device. Part I was mixed with the sand until a uniform coating was formed. Part II was then added to and mixed with the coated sand until a homogeneous sand mixture was formed. The total amount of binder (equal amounts of Part I and Part II) was 1.8% based on the weight of the sand.

The mixture of sand, polyol and polyisocyanate was blown into a conventional core cavity or a mold box for the production of standard pull briquette test cores, known as "dog bones". The «dog knots» test cores were hardened by exposure to a tertiary amine of the catalyst. This catalyst, namely dimethylethylamine, was suspended in carbon dioxide, an inert carrier gas. The cores were exposed to the amine catalyst for about 1 second (fumigation time) and then immediately removed from the molding box. The tensile strength was 12.74 kg / cm2 immediately upon exiting the box (1 minute),

15.75 kg / cm2 after 4 hours and 20.79 kg / cm2 after 20 hours.

The «dog bone» cores were used in shaking tests with aluminum castings. Seven "dog bones" were arranged in a form. The mold was equipped with a sprue system. The mold was designed to produce hollow castings with a metal thickness of approximately 6.25 mm on all sides. An opening was made at one end of the casting to remove the core from the casting. Molten aluminum at about 704 ° C, made from aluminum bars, was poured into the mold. After cooling for about 1 hour, the aluminum castings were broken off the sprue system and removed from the mold for shake-out inspection.

The shaking tests are carried out by placing a casting in a 3.785 liter jar. The vessel is placed on a shaker and shaken for 2 minutes. The weight of the sand core removed from the casting in this way is compared with the original weight of the sand core and the percentage shaking is calculated. Sand that remains in the casting after this treatment is removed by scraping and also weighed. The sand core, which was bound with the phenolic resin-polyisocyanate binder described above, could not be shaken out after the shaking treatment. The shaking was 0%. A comparison of this example with the preceding examples shows the advantages in terms of the shaking capacity when using an aminopolyol in a "cold box" system compared to other polyols which are used in "cold box" systems when casting at low temperatures Temperatures.

In the present description, the “cold box” process is understood to mean the process in which sand is blown into a mold with the polyisocyanate and the aminopolyol, and the curing takes place by gassing with a vaporous amine. The curing takes place very quickly. In the “no bake” process, as is also mentioned in the present description, the mixture of sand, polyisocyanate, polyol and optionally catalyst is poured into the mold, remains deformable for a certain time, but then hardens very quickly after this time .

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Claims (9)

647 965 1. A method for casting light metals using foundry articles that disintegrate or are brought to decay after casting, characterized in that (a) forms a foundry molding composition which contains an additive, a polyisocyanate and an aminopolyol, the additive making up at least 90% by weight of the molding composition, (b) forms this mass into a foundry article, (c) allows the mass so shaped to harden, (d) casting the light metal into a light metal casting using the molded, hardened foundry article, (e) solidify the cast metal, and (f) disintegrates the foundry article and removes it from the light metal casting. 2. The method according to claim 1, characterized in that the additive is sand and the light metal is preferably aluminum. 2nd PATENT CLAIMS 3. The method according to claim 1, characterized in that the amount of polyisocyanate 20 to 300 percent by weight based on the weight of the aminopolyol and the total amount of polyisocyanate and aminopolyol, preferably 0.7 to 2.5 percent by weight, calculated on the weight of the additive, is. 4. The method according to claim 1, characterized in that the aminopolyol contains at least one reaction product of ammonia or an amine with an alkylene oxide, e.g. a reaction product of propylene oxide with one of the amines diethylenetriamine, triethylenetetramine, ethylenediamine or mixtures thereof. 5. The method according to claim 1, characterized in that the foundry molding composition contains a catalyst for the image of urethane. 6. The method according to claim 1, characterized in that the aminopolyol is derived from an aromatic or aliphatic amine. 7. The method according to claim 1, characterized in that the aminopolyol is derived from propylene oxide or ethylene oxide. 8. The method according to claim 1, characterized in that the polyisocyanate and / or the aminopolyol is present as a solution in an organic solvent. 9. The method according to claim 1, characterized in that the aminopolyol is present in aqueous solution.