DE2923131C2 - Binder for foundry molds and cores for casting metals with a casting temperature of 982 ° C or less - Google Patents

Description

In the field of manufacturing foundry molds and cores, the cold-box process and the nobake process are known.

In connection with the cold-box process, there are already urethane-forming binders for binding corresponding molding materials (see. US-PS 34 09 579).

With regard to the no-bake process, binders are also used for molding materials for the production of foundry molds and cores described (see. US-PS 36 76 392).

In foundry technology, there has long been a need for suitable binder systems for the coldbox and no-bake processes, these binder systems being used for the production of foundry molds and - to enable cores that are suitable for the casting of light metals such as aluminum and magnesium, suitable. Corresponding known binders for these processes are found in the field of light metal casting do not have the desired properties of the forms and cores and also do not lead to good shaking behavior. If a sufficient amount of the binding agent is used to achieve the necessary strength and To achieve abrasion resistance of the molds and cores, the molds and cores do not disintegrate at the casting temperature of the light metals. (In the following, the term »light metals« always refers to metals with a GlelJtenaturatur of at most 982 ° C understood.) The consequence is a poor shaking behavior of the Forms and cores.

In US-PS 36 45 942 a method for the production of foundry binders on urethane basls, which can be easily peeled off in the green state and which have good disintegration behavior, is proposed, the '§

consists of the following measures: m

A) By mixing an aromatic polyisocyanate with a non-drying castor oil in such ®j Amount that the ratio of isocyanate to hydroxyl groups is from 1.5 to 8.0 is a prepolymer | produced rlsat, which is a first mass; P.

B) as a second mass is kulargewicht a mixture of a hydroxyl-containing material with a high molecular fc and produced an accelerator, wherein allphati- as hydroxyl-containing material || see polyether polyols or aromatic polyether polyols and, as an accelerator, a metal naphthenate, a || Organotin compound or a tertiary office used; | S

C) the first and the second mass are mixed in such an amount that the ratio of isocyanate to || Hydroxyl groups above 1.0 remain and that the amount of accelerator does not exceed 50 percent by weight of the prepolymer. '$

In a further embodiment, tung oil can also be incorporated into the prepolymer. jffj As hydroxyl group-containing substances with a high molecular weight, reaction products of | l Propylene oxide and / or ethylene oxide can be used with polyols or amines. However, the special %> Problems encountered when casting light metals. In US-PS 36 45 942 not addressed. '. " In GB-PS 14 51 461 a process for the production of foundry cores and molds on polyurethane base is jj

sis described by the cold-box method, the good resistance to sudden temperature changes _|;

gen ind show excellent disintegration behavior after metal casting. ':' '

For this purpose, a small substance in the form of a small particle is mixed with a binding agent that consists of: r ι

(a) a polyisocyanate;

(b) an aliphatic or aromatic polyether polyol and i

(c) an aromatic Hydroxyverblndung having at least two hydroxyl groups, which are bound directly or 'A via a methylene group to a carbon atom in an aromatic ring. ; i |

The mixture obtained is then shaped and cured in the presence of a catalyst.

The polyether polyols are aromatic or aromatic compounds with 2 to 6 hydroxyl groups. Question. Among other things, there are also reaction products of aliphatic diamines with ethylene oxide. Propylene oxide and tetrahydrofuran mentioned. The suitability of the binders, however, is only exemplified by the Cast steel explained in more detail. >

The invention is therefore based on the object of providing new binders for foundry molds and cores which, on the one hand, allow the production of non-fragile foundry molds and cores, however, on the other hand, these molds and cores easily disintegrate at temperatures below the casting temperatures of ferrous metals, e.g. B. bsi the casting temperature of aluminum or magnesium, allow. Included these binders should be able to be used according to the cold-box or the no-bake process.

This object is achieved by the invention.

The invention relates to the subject matter characterized in the claims.

It has been found that molds and cores binders are used for the production of foundries can based on the reaction between a polyisocyanate and an amine polyol with at least one tertiary Amino group - hereinafter referred to as "amin polyol" for short - basler, whereby urethanes are formed. i> The binder can be cured rapidly by using a gaseous tertiary amine as a catalyst. It has been found that a polyol prepared by reacting an amine with an alkylene oxide 1st, can be combined with a polyisocyanate to create a cold-box or no-bake binder system results after mixing with sand or another suitable molding material and the following Hardening allows foundry molds and cores to be produced, which have excellent processing properties, e.g. B. - " Strength. Abrasion resistance and lack of brittleness. These good qualities are simultaneous achieved with an excellent shaking behavior when casting non-ferrous metals. It is It is particularly important to emphasize that this combination of good processing properties and good shaking behavior Is particularly valuable and when the binders according to the invention are used in the field of metal casting is achieved at low temperatures. To harden the binder, a cata- ' analyzer can be used. Suitable catalysts for the cold-box process are gaseous tertiary amines or those amines which can be supplied in the form of a vapor. Preferred catalysts are Trlmethylamln, Dlmethyläthylamln and Trläthylamln. In the case of the no-bake process, there is no catalyst necessary part of the binder system. However, suitable catalysts can also be used in this case be added, preferably when certain amine polyols are used and a rapid '" Hardening is desirable. The curing of the binder according to the invention is based in part on the autocatalytic process Effect of amine polyols. Therefore, according to the invention, the no-bake method using a Two-component system instead of the typical urethane system that requires at least three components, be performed. Although the autocatalytic effect of the amine polyols used according to the invention This means a clear advance if it is also possible to use the binders according to the invention in individual cases to combine additional catalysts.

According to the invention, two-component systems are generally used to bind the molding material. Part A is the amine polyol. Part B is the polyisocyanate. Both parts are in liquid form. Generally as solutions in organic solvents. Forming urethanes for applying this binder system is "combines the Amlnpolyol the containing portion with which the Polylsocyanat containing portion *. When used in foundry technology, ie in the production of foundry molds and cores, one of the two parts is preferably first mixed with the molding material, such as sand. Then the other part is added. After the binder system has been uniformly distributed over the molding material, the molding compound obtained is shaped into the desired shape. The shape obtained can be left to stand and cures at room temperature. As already mentioned, the binding fluid systems based on the invention are generally autocatalytic to some extent. This means that after the amine polyol has been mixed with the isocyanate, the reaction thereof occurs and proceeds so rapidly that a catalyst is not required. The degree of reactivity between the amine polyol and the polyisocyanate depends on the reactivity of the polyol. The molding compositions formed into foundry molds or cores can also be cured by treatment with a gaseous catalyst. ^,

Despite the autocatalytic properties of the binder systems obtained according to the invention, the no-bake-process liquid Amlnkatalvsatoren or metallic catalysts are used, which In the Urethane technology are known. In some cases it is even expedient to use a catalyst preferred. By choosing a suitable catalyst, the conditions for producing a Foundry core chosen process, z. B. the processing time and the Ausalzelt, In the desired manner ^ can be set. For economic reasons it may be necessary when using certain polyols Therefore adding catalysts in order to achieve sufficient production rates.

The binders according to the invention can be used as catalysts in the cold-box process with gaseous amines be combined. The curing step can be carried out in such a way that a tertiary amine is added in a stream of inert gas entrains and the gas mixture obtained under sufficient pressure through the mold to be hardened «> conducts until the binder system has hardened.

The binders according to the invention only require an extremely short curing period, until a sufficient one Tensile strength of the mold to be hardened is reached 1st. This point of view is of great economic importance. The optimal hardening tents can easily be determined experimentally. Since only catalytic ones for hardening Quantities of the tertiary amine are required, generally a very dilute gas stream with h <is sufficient for this the catalyst. However, excess concentrations of the tertiary amine are also above that required Concentration not harmful to the hardened product. As an inert gas, for. B. air, carbon oxide or nitrogen can be used. In which 0.01 to 20 percent by volume of the tertiary amine are taken up.

Normal gaseous tertiary amines can be passed through the mold as such or after dilution. Suitable tertiary amines are gaseous partial amines, such as trimethylamine. However, also usually are liquid tertiary amines, such as Trläthylamln, in volatile form or in the form of a mixture with a gaseous one Medium In the same way for that; Insertion into the mold to be hardened is suitable. Although ammonia too, primary and secondary amines have a certain degree of effectiveness, the hardening reaction at room temperature to catalyze these compounds are not as beneficial as tertiary amines. Among the tertiary amines are also substituted amines, such as dimethylethanolamine, to be understood; They too can act as catalysts be used. Functional groups occurring as substituents in such amines, which reduce the effectiveness the tertiary amines do not affect, are z. B. hydroxyl, alkoxy, amino, alkylamino, Ketoxy ■ and thlo groups.

The amine polyols used according to the invention in binder systems are normally used as reaction products of an amine with an alkylene oxide. The term "amine polyol" is used in this Context to understand such a reaction product, but the designation does not refer to the Reaction products obtained by such a synthetic route is limited.

The alkylene oxides used to prepare the aforementioned amine polyols are preferably ethylene oxide and propylene oxide. However, other alkylene oxides can also be used for this purpose. The molar ratio of Alkylene oxide to AmIn can be very different. It is assumed that the degree of alkoxylation is none has a decisive influence on the property of the amine polyol obtained to act as a binder.

Examples of amines which, with alkyl enoxides, lead to amine polyols which can be used according to the invention are Ammonia, mono- and polyamines with primary and secondary amino groups. Specific examples are aliphatic Amines, such as primary alkyl amines, ethylene diamine, diethylenetrlamine and triethylenetetramine, cycloaliphatic Amines and aromatic amines such as o-, m- and p-phenylenedlamines and aniline-formaldehyde resins. Mixtures of the aforementioned amine polyols can also be used. Mixtures of aniine polyols are also used with other polyols, such as amine polyols, are suitable. It is assumed that amines, by Alkoxylation result in a polyol with at least two reactive hydroxyl groups, according to the invention can be used. The type of polyol used influences the conditions for the production of Gleßerelkkern. In the cold-box process, in which such a coated with the Blndemlttelsystem molding material, z. B. Sand, hardened by gassing with an AmIn as a catalyst, is the processing tent an essential one Property of the binder. As with the no-bake process, this processing tent is the tent during which the Sand mixed with the binding agent can be processed. After the binder with the Formsiioff has been mixed, the binder begins to react. After a certain time the reaction is ready advanced so that the mixture of sand and binding agent can no longer be processed. The tent after mixing the sand with the binder system up to the point at which this molding compound does not more that can be processed is called a “processing tent” in the cold-box process. It was found that the use of aromatic amine polyols resulted in an unexpected increase in processing time brings itself. This surprising result is of great value.

As mentioned above, it has been found useful to combine an amine polyol with another polyol. the can react with a polyisocyanate to mix. One advantage arises in particular with regard to the Strength of the foundry mold after treatment with the catalyst and after removal from the mold. Particularly Preferred in this context are phenolic resins containing hydroxyl groups, which are used in foundry technology are known as PEP resins (see US Pat. No. 3,485,797).

The binders according to the invention are combined with the second component of the binder system. These are all-phosphate, cycloaliphatic or aromatic polyisocyanates with preferably 2 up to 5 isocyanate groups. Mixtures of different polyisocyanates or isocyanate prepolymer can also be used. produced by reacting an excess of polyisocyanate with a polyhydric alcohol such as Toluylendllsocyanat and ethylene glycol, are used. Specific examples of suitable polyisocyanates are allphatlsche. Polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as 4,4'-dicyclohexylmethane isocyanate and aromatic polyisocyanates such as 2,4 ·· and 2,6-toluene-dylsocyanate, diphenylmethane-di-isocyanate and the corresponding methyl derivatives. Further examples of suitable polyisocyanates are 1,5-naphthalenedylsocyanate, Trlphenylmethanetrllsocyanat, Xylllendllsocyanat and the corresponding methyl derivatives, Polymethylene polyphenyl isocyanates and the corresponding methyl derivatives and also chlorophenylene-2,4-dylsocyanate. Although all polyisocyanates react with the amine polyol to form a crosslinked polymer structure aromatic polyisocyanates, in particular phenyl methane isocyanate, tri-phenyl methane isocyanate and their Mixtures, preferred.

The polyisocyanate is generally used in about the stoichlometric amount, i.e. H. In a crowd that sufficient to cure the amine polyol. However, this amount can also be used within certain limits deviated, which is even advantageous in some cases. In general, the polyisocyanate is in a Amount from 10 to 500 percent by weight, preferably 20 to 300 percent by weight, based on the amine polyol. used. The polyisocyanate is used in liquid form. Liquid polyisocyanates can be used in undiluted form Form can be applied. Solid or viscous polyisocyanates can be in this form or in the form of Solutions in organic solvents are added, the solvent in an amount up to 80 percent by weight of the solution is present.

Although this was used in combination with either the amine polyol or the polyisocyanate or both Solvent to a significant extent in the reaction between the isocyanate and the amine polyol does not participate, it can affect the response. The difference between the polyisocyanai and The polarity of the amine polyol limits the choice of solvents. In which both connections are contractual. This compatibility is necessary for a complete reaction and hardening of the To achieve binder according to the invention. Polar solvents of the protic or aprotic type are

good solvents for amine polyols. Therefore, solvents or combinations of Solvents used in which the solvent or solvents for the polyol with the solvent (s) ^) for the Po y'socyanate are compatible with one another. In addition to the aspect of compatibility, the Solvent for the polyol or the Poly.socyanat selected so that a low viscosity, a low Smell and a high boiling point can be achieved. Examples of such solvents are benzo and toluene Xylene Ethylbenzene and mixtures of these solvents. Preferred aromatic solvents are those and their mixtures that have a high aromatic content and a boiling range of 138 to 385 C.

^ Dle'poiaren solvents are not supposed to be extremely polar, so that they see when combined with the aroma Solvent incompatible. Suitable polar solvents are generally those de as Solvents are known, such as furfural, ethylene glycol monomethyl ether, glycol acetate, Athy lenglycolmonobutylätheracetat and isophorone. A few reactive polyols can also be used as l'mme ^ will. It has even been found that, under certain conditions, water can be used as the solvent

SKmSS of the B. demelt system are closed with each other and then with sand or a similar molding material? Molding compound mixed. The molding material can also be mixed with individual components one after the other. Methods for the distribution of the binder on the particles of Fonnstoffs are known _DTE molding composition may optionally contain other ingredients such as iron oxide, ^ "f ¹ *"'! ff £ * ^H £ ' £ $ £ dematerials pitch and refractory materials in powder form, contained. The 1-molding material, e.g. B. Sand, is in general η d the main component of the molding compound, while in contrast, the binding agent lays in a smaller amount. Although the sand is preferably used in dry form, a certain amount of "" moisture can be allowed. This is especially true if the solvent used does not mix with water

or an excess of polyisocyanate is required for curing. In the latter case, it reacts S polyisocyanate with the water. The water is a good solvent for the amine polyol

^since The excellent shaking behavior or the disintegration properties of the glacial se produced according to the invention are of different importance. The binders according to the invention disintegrate easily and thus enable the foundry core to be separated from the casting. So far, the shaking was at GleBl.ngen. the low temperatures below Sv, e.g. B. at 982 ° C or below, a major problem. In Z £ remote be hte.senmeta.le, w, e poured aluminum and magnesium at these temperatures ^ wlnn not decomposes the binder, this leads to large Difficult Celts in the separation of the sand Γοϊ öSηί OSS * with a low or Ausschütte.grad Degree of disintegration, ie with a low degree of degradation of the binder, require a longer period and high energy to separate the sand from the casting Energy supply. This improvement; due use te. ^ ^Ü ^ ⁵ Jf _Α ^ ^ "according to the invention of Amlnpolyolen Those skilled in the ^ known ■ J ⁸ ^ Jj J ^u * J ^ül telverfahren a foundry core from the amount of binder depends, of binding of the sand particles in a 7u «; Nurse-hanging foundry mold is used.

The binder used in the process, based on the weight of the sand, depends on the desired strength of the foundry core. As the amount of binding agent increases, the tension _also generally increases. of the foundry cores too. The amount of binder varies depending on the desired properties. A preferred quantity range for aie erfindungsge ™ - ^ ^{n Blnd} = ^m _ f reads at O 7 to 2 5% based on the molding material, z. B. sand. However, only 0.5% or 10% blndemite can be used. are used, with advantageous properties still being achieved for certain applications. However, it must also be taken into account that the greater the binding agent, the lower the degree of shaking.

p explain the invention. Parts and percentages relate to weight unless nothing otherwise stated 1st.

example 1

By converting 1.0 mol of ethyl chloride with 4.2 Mo! Propylene oxide is a propoxylated amine polyol produced. A 40 percent solution of the amine polyol is prepared in a commercially available aromatic solvent. This solution is called "Part I" in the following. . .... _AD ι

A 75 percent solution of a mixture of diphenyl methane di-cyanate and polymethylene polyphenylene isocyanate is separated from this made in an aromatic solvent. The isocyanate solution obtained

is referred to as "Part II". ,. ,. .

Washed and dried, finely ground sill clay oxide sand is placed in a mixer. Part I is mixed with the sand until the latter is evenly coated. Part II becomes the coated one Given sand and mixed in until homogeneous distribution is achieved. The polyisocyanate is made in Gerln-Bern Excess over the stoichlometric amount used to ensure a complete reaction of the hydroxyl group of the polyol. The proportion of binding agent (part 1 and part II) is 1 /,%, based on the weight

The mixture of sand, amine polyol and polyisocyanate is placed in a core box. Standard test specimens so-called "dog bones", produced to determine tensile strength. It turns out to be one Processing time of 5% minutes and a stripping time of 8 minutes. The tensile strengths according to 2, 4 and Hours are 2.07, 2.56 and 2.67 MPa.

The test specimens are used as cores in investigations of the pouring out with aluminum gels.

det. 7 of the aforementioned test specimens are arranged in a mold which is provided with a pouring system Is. The shape is designed in such a way that hollow correspondence with a metal layer thickness of about 6 mm is rare can be achieved. An opening is provided at one end of the glazing to remove the core from the glazing remove. Aluminum melted from aluminum blocks at a temperature of around 704 ° C becomes In * poured the mold. After about one hour of cooling, the aluminum castings are removed from the sprue system broken off and removed from the mold to perform the shake-out test.

This is done by pouring a glass into a container that holds about 3.79 liters. The container is placed on a shaker and kept in motion for 2 minutes. The weight of the sand core which is separated from the ground in this way becomes with the original weight of the sand core compared, from which the percentage of shaking is calculated. The sand that after shaking of the glutinous remains in this, is scraped out and also weighed.

It turns out that the sand core produced with the aforementioned binder according to the invention without Use of the shaking device and without the supply of external mechanical energy disintegrates and from the Alumlnlumgleßllng flows out. The amount to be extracted is 100%.

Examples 2 to 6

Test specimens are produced according to Example 1, the components specified below being used and the values specified below being obtained. Shaking out is also carried out according to - ¹ "Example 1.

example

Amine Diethylene A. triamine C. Alkylene oxide (AO) Propylene oxide 10 isoi AO: amine molar ratio 5.1: 1 without Amine polyol without Polyisocyanate C. 2 Solvent in the amine polyol,% 4OD 4.5 Solvent in the polyisocyanate,% without 1.5 catalyst without 50 Processing time, min 5 50 Stripping time, min 12th Binder,% 1.5 1.05 Part One, % 40 1.45 Part II,% 60 1.71 Tensile strength, MPa 100 2 hours 0.69 4 hours 0.71 24 hours Ul Shaking rate,% 100

Triethylene Ethylene B. tetramine diamine C. Propylene oxide Propylene oxide 6OD 6.2: 1 12: 1 25 D without C. C. 5 60 isophorone 6OD 8th 25 D 25 D 1.5 without without 50 0.5 6th 50 1.0 9 2.33 1.5 1.5 2.41 60 50 2.64 40 50 100 0.59 2.48 0.78 2.52 - 1.59 100 100

A = i nutthiinolamine B = propoxylated ethylenediamine. Molar ratio 4: 1 C - mixture of diphenylmethane diisocyanate and polymelhylene polyphenyl isocyanate IJ ■ = aromatic solvent

It turns out that the foundry cores without using the shaking device and without feeding external mechanical energy disintegrate and flow out of the equilibrium.

Example 7

Propoxyl sera of 1 mole of m-phenylenedlamine with 4.2 moles of propylene oxide becomes an aromatic amine polyol manufactured. A 40 percent solution of the aromatic amine polyol is prepared by dissolving in the aliphatic solvent ethylene glycol monobutyl ether. The resulting solution gives part I.

A 75 percent solution of a mixture of oil phenyl methane cyanate and polymethylene polyphenyl cyanate is produced using commercially available aromatic solvents. The isocyanate solution results in part II.

An approximately stoichiometric amount of the polyisocyanate is used to ensure complete conversion of the To achieve hydroxyl groups of the polyol.

Sand, which corresponds to the sand used in Example 1, is placed in a mixer. The Part I is mixed with the sand until the sand is evenly coated. In Part I, triethylenediamine was incorporated as a urethane catalyst. There are 0.8% catalyst, based on the Tel! 1, used. The part II is added to the coated sand and mixed until homogeneous distribution is achieved. I / ₂ % binder (Part I and Part II) based on the weight of the sand are used.

According to Example 1, test specimens are produced in a core box. The processing time is 70 minutes, the turn off 110 minutes. The tensile strength after 24 hours is 1.59 MPa.

According to Example 1, the test specimens obtained are used as cores in the casting of aluminum. Of the The shaking test is also carried out according to Example 1.

It turns out that the cores produced with the binder according to the invention without the use of the shaking device and disintegrate without supplying external mechanical energy and from the aluminum casting flow out. The amount to be extracted is 100%.

Examples 8 to U

Test specimens are produced according to Example 7, using the components specified below and the following values are obtained. The shake-out test with the aluminum rings takes place according to example 7.

example G 9 10 11th Aminopolyol E. E. F. F. Polyisocyanate C. C. C. C. Solvent in 40D 35 water 35 D 35 D Aminopolyol,% Solvent in 44 G without 35 G 35 G Polyisocyanate,% Catalyst,% 1.4 H. without without 1 V ₃ H Processing time, min 25th 10 11.5 7th Disengagement time, min 3i , ν-
ΙΟ ! 6 10.5 Binder,% 1.5 1.7 1.5 1.5 Part One, % 50 60 50 50 Part II,% 50 40 50 50 Tensile strength, MPa 2 hours 1.55 0.74 1.40 1.54 (3 hours) 4 hours _ 0.88 1.47 1.45 (3 hours) 24 hours 2.54 - 2.23 2.21 Shaking rate,% 92 _ 100 100

E = propoxylated aromatic amine F = ethoxylated aromatic amine C - mixture of aromatic solvent and kerosene H - mixture of 50% phenylpropylpyridine and 50% of a lithium salt of a carboxylic acid.

Disintegrate without using a shaking device and without supplying external mechanical energy the cores and flow out of the casting.

Example 12
Propoxylleren of one mole of o-phenylenediamine with 4.2 moles of propylene oxide creates an aromatic

made of polyol. Prepare a 40 percent solution of the aromatic amine polyol by dissolving In Isophorone. You get Tell I.

A mixture of Dlphenylmethandllsocyanat and Polymethylene polyphenylsocyanat is used as part II. A nearly stoichiometric amount of the polyisocyanate is used to complete the reaction of the hydroxyl groups of the polyol.

Sand, which corresponds to the sand used in Example 1, is placed in a mixing device. Part 1 is mixed in according to Example 1. In Part I, a 33 percent solution of triethylenediamine was incorporated as a urethane analyzer in dipropylene glycol. 1.0% catalyst, based on the weight of Part I., is used. The Part II is then added to the coated sand and mixed until it is evenly distributed. The amount of binder (55% Part I and 45% Part II) is Γ / ₂ %, based on the weight of the sand.

Test specimens are produced according to Example 1. The processing time is 9 minutes, the stripping is 20 Minutes. The tensile strengths after 2 and 24 hours are 2.00 and 2.16 MPa.

The test specimens obtained are used in accordance with Example 1 as cores for aluminum glazing. Afterward the shaking test is carried out according to Example 1.

It turns out that the cores produced with the binding agent according to the invention can be produced without the use of a shaking device and disintegrate without supplying external mechanical energy and fill out from the casting. The amount to be extracted is 100%.

Examples 13-15

Test bodies are produced according to Example 12, using the components indicated below and the values summarized below are obtained. Shaking the kernels out of the Gleßlingen is also carried out according to Example 12.

example 13th 14th 15th Amine m-phenylenediamine J aniline Alkylene oxide Propylene oxide Propylene oxide Propylene oxide Molar ratio AO: amine
in the amine polyol 4.2: 1 4.2: 1 2.2: 1 Polyisocyanate C. C. C. Solvent in
Amine polyol,% 60 isophorone 60 isophorone 6OK Solvent in the polyisocyanate without without without catalyst without without 1% Processing time, min 45 70 70 Stripping time, min 78 101 140 Binder,%
Part One, %
Part 11,% 1.5
55
45 1.5
73
27 1.5
61
39 Tensile strength, MPa
2 hours
4 hours
24 hours !, QQ
2.12
2.21 0.16
0.96 1.24 Shaking rate,% 89 100 74

J = aniline-formaldehyde resin

K = mixture of 40% ethylene glycol monobutyl ester acetate and 20% aromatic solvent

It turns out that the cores produced with the binder according to the invention without the use of a shaking device and disintegrate without supplying external mechanical energy and flow out of the glazing.

Example 16

An amine polyol is prepared by propoxylating 1.0 mole of m-phenylenediamine with 6.0 moles of propylene oxide. Prepare a 40 percent solution of the amine polyol with 60% of a solvent mixture, best

starting from 40% isophorone, 16.5% of an aromatic solvent and 3.5% kerosene. Tell I obtain.

A 75% solution of a mixture of diphenyl methane isocyanate and polymethylene polyphenyl isocyanate is prepared, in an aromatic solvent. The isocyanate solution represents part II. It an approximately stöchtometric amount of the polyisocyanate is used to ensure a complete reaction of the To achieve hydroxyl groups and the polyol.

Sand of the type used according to Example 1 is placed in a mixer. The Tell I is mixed with the sand until it is evenly distributed. Then the part U is added and also mixed in uniformly. The amount of binding agent (Part I and Part II in equal amounts) is 1/ ₂ %, based on the weight of the sand.

The mixture of sand, amine polyol and polyisocyanate is put into a standard core box for production blown from standard test specimens (to determine tensile strength), so-called "dog bones". the Test specimens are cured by gassing with a tertiary amine as a catalyst. Serves as a catalyst Dimethyläthylamln, which is mixed with carbon dioxide as an inert carrier gas. The specimens are about 20 Seconds (gassing time) exposed to the AmIn and then remain in the core box for 10 minutes (dwell time) they are taken from it. The tensile strengths are 0.17 MPa after removal (immediately), 0.50 MPa after 1 hour and 0.93 MPa after 24 hours. The test specimens obtained are used as cores according to Example 1 used in the casting of aluminum. The shaking test according to Example 1 is then carried out.

It turns out that the cores produced with the binder according to the invention without the use of a shaking device and without the supply of external mechanical energy they disintegrate and flow out of the blood vessel Shaking rate is 100%.

Examples 17-21

Cores are produced according to Example 16 using the components indicated below and checked. The values given below are obtained.

example 17th 18th 19th 20th 21 Amine aniline o-phenylene m-phenylene m-phenylene J 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 Polyisocyanate C. C. C. C. C. Solvent in the aminopolyol,% 6OL 60 isophorone 60 isophorone 60 L 60 isophorone Solvent in the polyisocyanate,% without 25 M. 25 D 25 M. without catalyst Trimethyl Dimethyl Dimethyl Dimethyl Trimethyl amine ethylamine ethylamine ethylamine amine in CO ₂ in CO ₂ in CO ₂ Fumigation time, see 10 10 10 20th 5 Dwell time, min 5 3 10 10 2 Tensile strength, MPa immediately 0.21 0.34 0.03 0.72 0.21 1 hour - 0.69 0.45 0.72 - 24 hours 0.62 0.59 0.78 - 0.34 Binder,% 1.5 1.5 1.5 1.5 1.5 (all components) Part 1, % 75 50 50 50 75 Part II,% 25th 50 50 50 25th Shaking rate,% 100 100 100 100 100

L = 40% isophorone. Ib. 5% aromatic solvents and 3.5% kerosene
M = IW aromatic solvent and 6% kerosene.

It turns out that the cores produced with the binder according to the invention without seed? one Schüuelvorrlchtung and disintegrate without the supply of external mechanical energy and separated from the belt.

Example 22

An amine polyol is produced by propoxyl sera of 1.0 mol of m-phenylenediamine with 8.0 mol of propylene oxide. A phenolic polyol is added to this in order to produce a polyol mixture. The ratio of o-amine polyol to amine polyol is 2: 1. A 60 percent solution of the polyol mixture in isophorone is prepared. You get Tell I.

A 75 percent solution of a mixture of Dlphenylmethanditsocyanat and Polymeihylenpolyphenyllsocyanat is prepared using 25% solvent, of which 19% aromatic solvent and Represent 6% kerosene. The isocyanate solution represents part II. It is an almost stoichlometric amount of the polyisocyanates are used to achieve a complete reaction of the hydroxyl groups of the polyols.

The mixture of Parts 1 and Il with sand takes place according to Example 16. The proportion of the binder (44% and 56% part Ϊ Part II) is l '/ _2%, based on the weight of the sand.

According to Example 16, the mixture of sand, polyol and polyisocyanate is blown into a core box. The hardening takes place by adding dimethylethylamine mixed with carbon dioxide. The test specimen are treated with the catalyst for about 5 seconds and then Im for a residence time of 1 minute Core box left before being removed therefrom. The tensile strengths are 0.40 MPa immediately after removal, 1.38 MPa after 1 hour and 1.45 MPa at the point of pouring.

According to Example 1, the test specimens are used as cores when casting aluminum. Below the shaking test according to Example 1 is carried out.

It turns out that the cores produced with the binder according to the invention disintegrate without the use of a shaking device and without the supply of external mechanical energy and flow out of the glazing. the Distribution amount is 100%.

Examples 23 and 24 example

23

Amine

Alkylene oxide

Aminpolyo!

Am in-free polyol

Amine polyol ratio: amine-free polyol

Polyisocyanate Solvent in the polyol mixture Propylene oxide

phenolic polyol 2: 1

phenolic polyol 2: 1

40% ethylene glycol monobutyl ester acetate

40% ethylene glycol monobutyl ester acetate

Solvent in the polyisocyanate 25% M, 6% kerosene 1.5 25% kerosene 1.5 catalyst Trimethylamine 44 Trimethylamine 50 Fumigation time, see 5 56 5 50 Dwell time, min 1 100 1 48 Tensile strength, MPa 0.31 0.36 0.88 (1 hour) 0.86 (1 hour) 0.76 (4 hours) - 1.12 (time of 0.88 (time of Casting) Casting) Binder,% (all components) Part 1, % Part II,% Shaking rate,%

N »olhoxylated aromatic amine polyol

It is evident that the cores produced with the binder according to the invention disintegrate without the use of a shaking device and without the supply of external mechanical energy and flow out of the casting

If the binder according to the invention was omitted, a shaking device had to be used to to achieve the amount of shedding given above.

Example 25

An amine polyol is prepared by propoxylating 1.0 mole of ethylene diamine with 8.0 mole of propylene oxide. A 50% solution of the amine polyol is prepared in 50% of a solvent mixture consisting of 30% isophorone, 16.5% of a common aromatic solvent and 3.5% kerosene. Tell I obtain.

A 75 percent solution of a mixture of diphenyl methane isocyanate and polymethylene poly- "> phenyl isocyanate produced using 25% of a solvent mixture consisting of 19% of an aromatic solvent and 6% kerosene *. The isocyanate solution is part II. It is about Stoichlometric amount of the polyisocyanate used to ensure a complete reaction of the hydroxyl groups of the To achieve polyols.

According to Examples 17 to 21, the sand mentioned in Example 1 is mixed with parts I and II. The ^{| ς} amount of beef agent (Part I and Part II in equal amounts) is 1 %%, based on the weight of the sand.

According to Example 16, test specimens are produced from the molding compound. Curing takes place with triethylamine, the test specimens are gassed for about 10 seconds and then for a dwell time of Remain in the core box for 5 minutes before removing them. The tensile strengths are 0.55 MPa 15 minutes after gassing and 0.93 MPa after 24 hours. 2 »

The test specimens obtained are used according to Example 1 as cores when casting aluminum. The shaking test according to Example 1 is then carried out.

It turns out that the cores produced with the binder according to the invention disintegrate without the use of a shaking device and without the supply of external mechanical energy and flow out of the glazing. the Shaking rate is 100%. :?

Example 26

A 58.5 percent solution of a phenolic polyol in an aromatic solvent is prepared. You get Tell I. ■ '"

In addition, a 75 percent solution of a mixture of diphenyl methane isocyanate and polymethylene polyphenyl isocyanate is prepared in 25% of a solvent mixture, 19% of which is aromatic Solvent and 6% kerosene. The isocyanate solution is part II. It is about Stoichlomelrlsche amount of the polyisocyanate used to ensure a complete reaction of the hydroxyl groups of the To achieve polyols. ^

According to Example 1, the sand mentioned there is mixed with parts I and 11. It becomes the binder (Same amounts of Part 1 and Part II) In an amount of 1.8%, based on the weight of the sand, used.

According to Example 16, test specimens are produced from the molding compound obtained, which by gassing with Dlmethyläthyiamln to be hardened in a mixture with carbon dioxide. The test specimens are attached to the catalyst exposed for about 1 second and then immediately removed from the core box. The tensile strengths are 1.25 MPa immediately (1 minute) after removal from the core box, 1.55 MPa after 4 hours and 2.04 MPa after 20 hours.

The test specimens obtained are used according to Example 1 as cores when casting aluminum. The shake-out test is then carried out according to example 1. ■> ■>

It turns out that the kernels are not shaken out after the treatment on the shaker can. The amount shaken out is 0%.

Claims (7)

Patent claims: 1. Binder for foundry molds and cores for casting metals with a casting temperature of 982 ° C maximum, consisting of a polyhydroxy compound and a polyisocyanate. characterized in that it is a polyhydroxy compound from 20 to 1000% by weight, based on the polyisocyanate. Contains amine polyol with at least one tertiary amine group. 2. Binder according to Claim I _1, characterized in that the amine polyol is an aromatic amine polyol. 3. Binder according to claim 1, characterized in that the amine polyol is a reaction product from ammonia or an aliphatic amine and an alkylene oxide. 4. Use of the binder according to any one of claims 1 to 3 for the production of molds and Cores for casting metals with a casting temperature not exceeding 982 ° C using the no-b ^ ke process. 5. Use of the binder according to claim 4 for the purpose according to claim 4, characterized in that a catalyst is additionally used. 6. Use of the binder according to one of claims 1 to 3 for the production of molds and cores for the casting of metals with a casting temperature of at most 982 ⁰ C after the cold-box method. 7. Use of the binder according to one of claims 4 to 6 for the purpose according to claim 4 or 6. characterized in that an amin-free polyol is also used.