WO2005092539A1

WO2005092539A1 - Novel catalytic composition

Info

Publication number: WO2005092539A1
Application number: PCT/CA2005/000460
Authority: WO
Inventors: Antonio Mancuso; Satish Jhaveri
Original assignee: Mancuso Chemicals Limited
Priority date: 2004-03-29
Filing date: 2005-03-29
Publication date: 2005-10-06

Abstract

A novel catalyst composition for use in a cold-box sand casting system is provided. The catalyst composition comprises a tertiary amine dissolved in a solvent. The catalyst composition may be provided in liquid or vaporized form. A binder system using the catalyst composition and methods of preparing cores and molds using the catalyst composition are also provided.

Description

NOVEL CATALYTIC COMPOSITION

FIELD OF INVENTION

[0001] The present invention relates to a process and composition for preparing foundry shapes, such as molds or cores, which are used for metal castings.

BACKGROUND OF THE INVENTION

[0002] Metal casting generally involves heating a metal above its melting point and pouring the metal into a mold. The mold comprises a cavity which is filled with the molten metal. The mold typically also comprises at least one core. The cores are used to form the interior contours, such as internal cavities or cuts, of a casting as the metal solidifies around the outside of the core.

[0003] Sand casting is one of the major methods used by the foundry industry in the production of metal parts and metal castings. In this process, sand mixed with an appropriate binding agent is used to make the mold and core. When a binder system is mixed with sand or another aggregate and allowed to cure at room temperature a resin coated sand mold or core is produced.

[0004] There are two major types of sand casting for the preparation of metal parts. These are termed the "no-bake" process and the "cold-box" process. In the no-bake process the aggregate is mixed with a liquid curing agent and then formed into a desired shape. In the cold-box process, a gaseous curing agent is used to set the aggregate of sand and resin.

[0005] In the cold-box process, the binder system typically comprises three components, a phenol-formaldehyde resin component, a polyisocyanate component and a catalytic component. United States Patent No. 3,409,579 discloses a cold-box process. The catalytic component in a cold-box system is typically a gaseous catalyst. The catalyst is added to control the speed of the binder curing. In one such system, termed a phenolic-urethane cold-box (PUCB) process, a phenolic resin and isocyanate are mixed with sand and then an amine catalyst is introduced. After the reaction, the excess amine catalyst is then released from the resulting polyurethane molecule. Examples of tertiary amines that are commonly used in this process include TEA (triethyl amine), DMIA (dimethyl isopropyl amine), and DMEA (dimethyl ethyl amine).

[0006] United States Patent No. 5,582,231 (Siak et al.) discloses the use of core blowing equipment. The gas and/or air passes through the holes through which the sand is blown into the corebox or through vents in the upper surface of the corebox. After the reaction, the air which will contain excess gaseous amines, is purged through the core into the exhaust manifold where it can be collected and directed to a scrubber to remove noxious gas from the air.

[0007] The cycle time for preparing cores and removing them from the corebox is very important in determining the cost of a coremaking process. A reduced cycle time with reduced resin wipe-off and lower binder addition would inevitably lead to increased productivity.

[0008] As discussed above, the catalyst controls the rate of cure of the mold. Thus, a catalyst that was able to speed up the process would obviously be beneficial. The FOSECO Group, in their "Eshamine plus" process use TMA, trimethyl amine, which is available in the gaseous phase as a catalyst. TMA is one of the most reactive in the family of tertiary amines. However, although TMA is a very efficient catalyst, there are many difficulties associated with its use. Because it is a gas, it is difficult to estimate how much is being fed to the lines and it is also difficult to contain TMA without extensive reworking of machinery to prevent leaks. In addition to the many health risks associated with inhalation of trimethyl amine, this gas also has a very strong and unpleasant fishy odour which has limited its use in sandcasting applications. Thus, there remained a real and unmet need for a new process for sandcasting which would result in a reduced cycle time through more efficient amine catalyst use and which would be environmentally friendly.

SUMMARY OF THE INVENTION

[0009] Isocyanates are the building blocks from which polyurethane products are made. When isocyanate is reacted with a phenolic resin in the presence of a tertiary amine catalyst, polyurethane is formed. This binder system is used in the foundry industry to strengthen molds and cores. The present invention provides a novel process and catalyst composition for the production of polyurethane.

[0010] In addition to its usefulness in the preparation of cores and molds for use in the foundry industry, the catalyst composition of the present invention is useful in other polyurethane curing processes such as in paint making and the manufacture of hard plastics. In fact, it is useful in any urethane vapor cure system.

[0011] In one aspect of the invention, a novel catalyst composition is provided. The catalyst composition comprises an amine dissolved in a solvent. Preferred amines are tertiary amines such as trimethyl amine (TMA), triethyl amine (TEA), tributyl amine (TBA), dimethylethyl amine (DMEA), dimethylisopropyl amine (DIPA) and dimethylpropyl amine (DMPA). Preferred solvents for use in the present invention are water and alcohols including methanol, ethanol, propanol, isopropanol, butanol and isobutanol and combinations thereof.

[0012] In another aspect of the invention a cold-box foundry binder system is provided. The binder system comprises a) 40 to 60 parts by weight of Part 1 comprising a curable resin in a solvent, b) 40 to 60 parts by weight of Part 2 comprising isocyanate in a solvent, and c) an effective amount of a tertiary amine catalyst dissolved in a liquid.

[0013] In preferred embodiments Part 1 comprises 30 to 70% of a phenolic resin and 70 to 30% solvent and Part 2 comprises 65 to 95% isocyanate in 35 to 5% solvent. The curable resin is preferably a phenolic resin prepared by reacting a phenol with an aldehyde. The isocyanate is preferably an organic polyisocyanate in a non-reactive organic solvent. Isocyanate is 4-4' diphenyl methane diisocyanate is one such isocyanate.

[0014] In one preferred embodiment, the liquid that the catalyst is dissolved in is water. In another preferred embodiment, the liquid is alcohol. Examples of useful alcohols include, but are not limited to ethanol, methanol, isopropanol, propoanol, butanol and methylol.

[0015] The binder system of present invention preferably comprises a tertiary amine as a catalyst. The tertiary amine is preferablyselected from the group consisting of TMA, TEA, TBA, DMEA, DIPA, DMPA and mixtures thereof and is most preferably TMA.

[0016] In another aspect of the invention, a novel catalyst composition for use in a cold-box system is provided. The catalyst composition comprises TMA dissolved in water, alcohol or combinations thereof.

[0017] In a further aspect of the invention, a process for preparing a foundry shape is provided the process comprises the steps of a) combining sand with Part 1 of a binder system where Part 1 is a phenolic resin, b) adding part B, an isocyanate, of a binder system as defined in claim 1 to form a sand-binder mixture; c) blowing the mixture into a corebox; and d) contacting the mixture with a vaporized amine catalyst dissolved in a solvent composition in the corebox for a time sufficient to cure the resin. The catalyst composition is preferably TMA dissolved in alcohol or TMA dissolved in water or TMA dissolved in a combination of water and alcohol. The catalyst composition may be provided vaporized

[0018] In another aspect of the invention, there is provided a method of making a sand core. The method comprises the steps of: a) providing a corebox; b) blowing a mixture of sand and a binder into the corebox to form a core, said binder comprising isocyanate and phenolic resin; c) passing a vaporized catalyst composition, comprising a tertiary amine dissolved in a solvent, into the core; d) holding the core in contact with the catalyst composition for a time sufficient to cure the binder; e) removing excess catalyst composition from the corebox; and f) releasing the cured core from the corebox. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The features of the present invention will become more apparent from the following description in which reference is made to the appended drawing wherein:

[0020] Figure 1 illustrates the chemical reactions involved in the curing of polyurethane.

DETAILED DESCRIPTION

[0021] The present invention relates to a novel method for making a sand core or mold and a novel catalytic composition for use therein. As used herein, the terms "core" and "mold" are used interchangeably to refer to a solidified sand structure comprising sand and cured binder that can be used for the preparation of metal castings. While this detailed description refers specifically to sand, it is clearly apparent that the binder system and general method of the present invention can be used with other aggregates. It is also apparent that while the detailed description and the examples illustrate specific embodiments of the invention, the invention encompasses equivalent embodiments.

[0022] Cores or molds for metal castings are normally prepared by mixing an aggregate such as sand with a binder system such as a phenolic urethane binder. The mixture is then blown to form the desired shape or form of the core or mold. Once the mixture has been blown into the desired shape, it is then cured to a solid. In the cold-box process of sand casting, sand is mixed with a two part binder and then cured by contacting the binder with a gaseous catalyst.

[0023] In one aspect of the invention, a foundry binder composition is provided. The foundry binder binds together aggregate material, typically sand, in a preformed shape. A foundry binder typically comprises a part 1 binder component and a part 2 binder component. A catalyst component is sometimes termed a part 3 component. In a cold box process a foundry core or mold is prepared by mixing sand with a part 1 binder component and a part 2 binder component, discharging the mixture into a pattern, and curing the mixture by passing a vaporous catalyst through the mixture of sand and resin.

[0024] Typically, the part 1 binder component is a phenolic resole resin in a solution of organic solvents and/or plasticizers. One preferred part 1 binder component is CBA 888, made and sold by Mancuso Chemicals. Another preferred part 1 binder component useful in the cold box process is CBA 990 - Mancuso Chemicals. It is clearly apparent that other Part 1 binder components known to those in the art can also be used.

[0025] The phenolic resins that are useful the present invention may be obtained by the reaction of a phenol, such as phenol itself, cresol, resorcinol, 3,5-xylenol, bisphenol-A, other substituted phenols, and mixtures of any of these compounds, with an aldehyde such as, for example, formaldehyde, paraformaldehyde, acetaldehyde, furfuraldehyde, and mixtures of any of these aldehydes.

[0026] Various types of phenolic resins that are known to those skilled in the art can be used in the present invention. Preferred phenolic resins include CBA 888. Various types of phenolic resins useful in the cold-box sandcasting process are described in United States Patent Nos. 3,409,575, 6,017,978 and 6,365,646.

[0027] Typically, the part 2 binder component is a polymeric isocyanate in a solution of organic solvents and/or plasticizers. One preferred part 2 binder component is CBB 176, made and sold by Mancuso Chemicals. Other preferred part 2 binder components useful in the cold box process include CBB 176C, CBB 920M and other known to those in the art.

[0028] Various types of isocyanate component can be used in the binder according to the present invention. These include polyisocyanates and organic polyisocyanates such as tolylene-2,4-diisocyanate, tolylene-2,6- diisocyanate, and mixtures thereof, particularly crude mixtures thereof that are commercially available. Other typical polyisocyanates include methylene- bis-(4-phenyl isocyanate), n-hexyl diisocyanate, naphthalene-1 ,5- diisocyanate, cyclopentylene-1 ,3-diisocyanate, p-phenylene diisocyanate, tolylene-2,4,6-triisocyanate, and triphenylmethane-4,4\4"-triisocyanate and higher isocyanates. Isothiocyanates and mixtures of isocyanates can be employed. Crude polyisocyanates that are commercially available, and polyaryl polyisocyanates can also be used in the present invention.

[0029] The part 1 binder component and the part 2 binder component are typically dissolved in solvents and/or plasticizers. The solvents provide component solvent mixtures of desirable viscosity and facilitate coating foundry aggregates with the part 1 and part 2 binder components. The total amount of a solvent can vary widely, but is preferably in a range of from about 5% to about 70% by weight, based on the total weight of the part 1 binder component, more preferably from about 20% to about 60% by weight. For the part 2 binder component, the solvent is preferably in the range of from about 1 % to about 50% by weight, more preferably from about 5% to about 40% by weight.

[0030] Hydrocarbon and polar organic solvents such as organic esters are typically used. Examples of hydrocarbon solvents include aromatic hydrocarbons such as benzene, toluene, xylene, ethyl benzene, high boiling aromatic hydrocarbon mixtures, heavy aromatic naphthas, etc. Paraffin oil may also be used. A variety of ester-functional solvents are also useful in embodiments of the present invention.

[0031] Although the solvents employed in combination with either the part 1 binder component or the part 2 binder component do not significantly affect the reaction between parts one and two, they should be compatible to promote complete reaction and curing of the binder composition.

[0032] Additives normally utilized in foundry manufacturing processes can also be added to the compositions during the sand coating procedure. Such additives include silanes and materials such as iron oxide, clay, carbohydrates, potassium fluoroborates, wood flour and the like.

[0033] Curing of the binders of the present invention generally takes place at ambient temperature, however in certain situations it may be desirable to preheat the sand to accelerate the reaction. [0034] The aggregate material commonly used in the foundry industry include silica sand, construction aggregate, quartz, chromite sand, zircon sand, olivine sand, or the like.

[0035] In another aspect, the present invention provides a process for making foundry cores and molds. The process comprises admixing aggregate material with at least a binding amount of the part 1 binder component and the part 2 binder component. A tertiary amine catalyst is dissolved in a solvent and then vaporized to react with the binder and cause curing of the resin. A sufficient amount of catalyst is applied to the uncured core or mold to catalyze the reaction between the components. The admixture is cured forming a shaped product. The flow rate of the vaporous catalyst is dependent, of course, on the size of the shaped admixture as well as the amount of binder therein. By dissolving the catalyst in a solvent, rather than using a gaseous catalyst as used previously, the efficiency of the curing process is greater increased and the amount of catalyst required can be reduced as much as 50-80%.

[0036] The sand may be first mixed with the Part 1 binder component and then the Part 2 component or vice versa. The components may be mixed with the aggregate material either simultaneously or one after the other in suitable mixing devices, such as mullers, continuous mixers, ribbon blenders and the like, while continuously stirring the admixture to insure uniform coating of aggregate particles.

[0037] The quantity of binder can vary. Usually about 0.4 to about 6 weight percent of binder based on the weight of the aggregate and preferably about 0.5% to 3.0% by weight of the aggregate is used. A significant amount of the binder composition to completely coat all of the sand particles and to provide a uniform admixture of the sand and binder is preferably used.

[0038] The efficiency of the coremaking process is dependent upon, among other things, the catalyst used in the binder. Various catalysts provide different reaction rates. Tertiary amines have been shown to be efficient catalysts when used in combination with a phenolic resin and isocyanate. The curing step is accomplished by suspending a tertiary amine catalyst in an inert gas stream and passing the gas stream comprising the tertiary amine, under sufficient pressure to penetrate the molded shape until the resin is cured.

[0039] TMA is a very reactive tertiary amine, which is known to be an effective catalyst in the reaction from polyisocyanate components to a fully hardened polyurethane. The steps involved in this reaction are illustrated in Figure 1.

[0040] While tertiary amines such as TMA have been shown to be effective catalysts, the use of tertiary amines in the production of sand cores has been limited by several factors. Because the tertiary amine is provided in a gaseous form, modifications to the equipment must be made to try and prevent or at least reduce the amount of gas leakage into the environment. It is nearly impossible to ensure that all of the equipment is gas leak proof and it may be necessary to provide new equipment. In addition to the health risks associated with the inhalation of tertiary amines, these gases have a strong fishy odour that is very unpleasant to work around.

[0041] The present invention provides a novel binder system that is highly effective in the process of cold-box sand casting. It has now been found that improved results are obtained if the curing process is carried out using a tertiary amine catalyst dissolved in a liquid carrier instead of being provided in a gaseous form. In this way the benefits of using an amine, such as efficient catalysis can be achieved without the problems associated with the gaseous form. Because the amine is dissolved in a liquid, its dispersion is easier to control. The need for tight fitting equipment to prevent gas leaks is reduced and the working conditions are improved. In addition, the dissolved amine can be easily vaporized and the catalyst molecules are rapidly dispersed throughout the core/mold. This provides for more controlled introduction of a specific amount of catalyst thereby reducing waste. Excess catalyst may be recovered with the liquid and the liquid can be recharged and reused. Vaporization is used to disperse the catalyst. This method using a dissolved catalyst also reduces the need for complex exhaust systems to rid the air of noxious gases. Because the catalyst is dissolved in a solvent and the composition typically comprises about 5 to 30% TMA, the odor associated with gaseous TMA is greatly reduced even when the composition is vaporized.

[0042] In one aspect of the invention, a catalyst composition comprises a tertiary amine catalyst dissolved in alcohol. Preferred alcohols include isopropanol, ethanol, methanol, propanol, butanol and other alcohols well known to those skilled in the art. TMA is a preferred tertiary amine to be dissolved in an alcohol since it has a low boiling point and a very unpleasant odour. TMA is also a highly efficient catalyst and is cheaper than most other tertiary amines.

[0043] The use of TMA dissolved in alcohol provides the surprising result that productivity can be greatly increased. Cure times are significantly reduced and less TMA is required for curing to occur. It has been found that compositions comprising from about 5 to 30% TMA in alcohol can effectively cure a phenolic resin. Without being limited by explanation, the increased efficiency seen when TMA is dissolved in alcohol and the resultant composition is vaporized and injected into the corebox may be due to the alcohol reacting with the isocyanate and "carrying" the TMA to the active site of cure more efficiently. It is believed that the alcohol increases the rate of dispersion of TMA and provides for more efficient utilization of the catalyst.

[0044] In another aspect of the invention, the binder system comprises a tertiary amine dissolved in water. When the in solution is vaporized it is an effective catalyst in the cold-box process. The amine is efficiently distributed throughout the mold/core to provide a high quality bonded sand product for metal casting. It is postulated that the water molecules may react with isocyanate and thus enhance the permeation of the low molecular weight catalyst molecules throughout the core or mold.

[0045] Other amine catalysts, in addition to TMA, may also be more efficiently used by dissolving them in a liquid carrier. These include TEA, DMEA, DIPA, DMPA, etc. Thus, in one aspect, the present invention provides a novel binder catalyst composition comprising an amine dissolved in a solvent. The use of a solvent as a carrier for the catalyst has many advantages. In addition to controlling the dispersion of gases and the associated smells, the use of a catalyst composition comprising catalyst dissolved in a solvent provides a better efficiency of catalyst use. The amount of catalyst required for complete curing can be significantly decreased.

[0046] The present invention provides a cold-box foundry binder system that comprises a phenolic resin, isocyanate and a tertiary amine catalyst in a liquid carrier. The isocyanate component of the foundry binder system typically comprises a polyisocyanate in an organic solvent. Mixtures of polyisocyanates as well as blocked polyisocyanates and polyisocyanate prepolymers can also be used. Various types of phenols can be reacted with an excess of aldehyde, as known to those skilled in the art, to form the phenolic resin of the binder system. The phenolic resin is typically provided as a solution in an organic solvent. There should be compatibility between the solvents used for the isocyanate and the phenolic resin to ensure complete reaction and curing of the binder compositions.

[0047] The present invention also provides a method of making sand cores. The cores are solid reproductions of the hollow spaces desired within the finished castings. The cores are made from a mixture of silica sand, phenolic resin and isocyanate. A corebox is provided and the mixture is injected into the corebox.

[0048] The mixture is cured in the corebox by introducing a tertiary amine dissolved in a solvent that is vaporized just prior to introduction into the corebox. Rapid dispersion of the catalyst reduces the coremaking cycle time. The core and the binder composition are maintained in contact for a sufficient time so as to cure the binder. The system is then purged with air to remove the excess catalyst composition. Excess catalyst composition is typically sent to a scrubber and then the air is exhausted. In a preferred embodiment, catalyst composition is collected after the curing step and recycled. In a particularly preferred embodiment, the amine that is released from the reaction is again dissolved in the solvent and recycled. [0049] The method of the present invention has many advantages over prior art methods. In addition to more rapid diffusion of the catalyst in the coremaking machine, there is reduced exposure to gaseous amine catalysts. Some of the tertiary amines used as catalysts have been shown to irritate the eyes, mucous membranes and skin. They are also known to cause blurred vision, headache, nausea, and faintness. In a standard coremaking process, the solidified cores are removed after the reaction and placed on storage racks. As the cores are stored, they continue to leach excess amines resulting from the release of the amine at the end of the reaction. This pollutes the air in the area. In the present invention, the release of tertiary amines from the stored cores is reduced because, at the end of the reaction, there is less excess tertiary amine and it is more easily removed. In addition, prior art methods involve exhaust ventilation systems to help purge the excess amine gas from the cores. In the present invention, the dissolved tertiary amine can be collected and recycled.

[0050] The above disclosure generally describes the present invention. A more complete understanding can be obtained by reference to the following specific examples. These examples are described solely for purposes of illustration and are not intended to limit the scope of the invention. Changes and form and substitution of equivalent are contemplated as circumstances may suggest or render expedient. Although specific terms have been employed herein, such terms are intended in a descriptive sense and not for purposes of limitation.

EXAMPLES

[0051] Although specific terms have been used in these examples, such terms are intended in a descriptive sense and not for purposes of limitation. Methods of coremaking referred to, but not explicitly described in the disclosure and/or in these examples are reported in the scientific literature and are well known to those skilled in the art. Example 1. Use of gaseous TMA as a catalyst in a sand core making process.

[0052] A binder composition comprising 55% phenolic resin (CBA 888) and 45% isocyanate (CBB 176) was mixed with silica sand. The mixture comprised about 1.2% of the binder composition in the sand. The mixture was placed in a mold and TMA was applied using a gassing unit for different times. The system was then purged with air for varying amounts of time as shown below in Table 1. The air was vented into a dilute HCI solution.

Table 1. TMA in Gaseous Form

[0053] In testing embodiments of the present invention, tensile strengths of the cores prepared as noted above were determined using a Thwing-Albert Tensile Tester (Philadelphia, Pa.). This device consists of jaws that accommodate the ends of a "dog-bone-shaped" test core. A load is then applied to each end of the test core as the jaws are moved away from each other. The application of an increasing load continues until the test core breaks. All of the samples showed a good tensile strength in the range of approximately 250 psi.

[0054] The experiment was repeated and the strength of cured cores was tested after two weeks of storage and the results are shown in Table 2 below. Table 2. Tensile Strength After Two Weeks

[0055] These results indicate that curing with TMA produces better results in terms of characteristics of the cores, such as strength and humidity resistance, as compared to other catalysts such as TEA, DMEA, DIPA and DMPA. However, a major issue in these runs was the pungent odour associated with TMA.

Example 2. Use of TMA dissolved in Methanol as a Catalyst.

[0056] A silica sand/phenolic resin/isocyanate mixture was prepared as described above in Example 1. As above, the mixture was placed in a laboratory tensile dog bone machine. A 20% TMA in methanol composition was prepared and was vaporized into the machine for various times and then the system was purged with air. The results from this experiment are shown in Table 3 below.

Table 3. TMA in MeOH

[0057] These results indicated that 10%TMA in MeOH works efficiently to cure a sand core. The TMA odour was significantly reduced by dissolving the amine in the alcohol.

Example 3. Use of TMA in Isopropanol.

[0058] A silica sand/phenolic resin/isocyanate mixture was prepared as described above in Examples 1 and 2. In this experiment, 20% TMA dissolved in isopropanol was used as the catalyst. The results are shown in Table 4 below.

Table 4. TMA in IPA

[0059] These results indicate that TMA dissolved in isopropanol is an effective catalyst. The smell associated with the process was considered acceptable to the employees involved.

Example 4. Comparison of DMA and TMA in isopropanol.

[0060] In this experiment, lake sand rather than silica sand, was used to prepare a sand/phenolic resin/isocyanate mixture. 1.2% phenolic resin/isocyanate (55:45) in sand was used as in previous runs. Either 30% DMA in isopropanol or 20% TMA in isopropanol was used as a catalyst. The results obtained with DMA in IPA are shown in Table 5 below and the results obtained with TMA in IPA are shown in Table 6.

Table 5. DMA in IPA

Table 6. TMA in IPA

[0061] These results indicate that in comparative studies, TMA in IPA performed well giving rise to well cured cores while DMA in IPA is an ineffective catalyst and the cores that resulted from its use were too soft. Example 5. Trimethyl amine in Water as a catalyst for Phenolic Urethane cold box system:

25-26 % Trimethyl amine in water and 20% Trimethyl amine in water were analyzed for their catalytic activity in a PUCB system. The results are shown below: Sand test Results: Part I CBA 888 Part B CBB 176 Total Binder 1.5% l/ll ratio 55:45 Table 7. TMA in IPA

[0062] Water as a solvent with TMA is an efficient catalyst composition for curing of a Phenolic Urethane system. The humidity resistance is considerably improved.

Claims

I claim: 1. A cold-box foundry binder system comprising: a) 40 to 60 parts by weight of Part 1 comprising a curable resin in a solvent, b) 40 to 60 parts by weight of Part 2 comprising isocyanate in a solvent, and c) an effective amount of a tertiary amine catalyst dissolved in a solvent.

2. A binder system according to claim 1 wherein Part 1 comprises 30 to 70% of a phenolic resin and 70 to 30% solvent.

3. A binder system according to claim 1 wherein Part 2 comprises 65 to 95% isocyanate in 35 to 5% solvent.

4. The binder system of claim 1 wherein the curable resin is a phenolic resin, prepared by reacting a phenol with an aldehyde.

5. The binder system of claim 1 wherein the isocyanate is an organic polyisocyanate in a non-reactive organic solvent.

6. The binder system of claim 5 wherein the isocyanate is 4-4' diphenyl methane diisocyanate.

7. The binder system of claim 1 , wherein the solvent is water.

8. The binder system of claim 1 , wherein the solvent is alcohol.

9. The binder system of claim 5, wherein the alcohol is selected from the group consisting of ethanol, methanol, isopropanol, propoanol, butanol and methylol.

10. The binder system of claim 1 wherein the tertiary amine is selected from the group consisting of TMA, TEA, TBA, DMEA, DIPA, DMPA and mixtures thereof.

11.The binder system of claim 11 wherein the tertiary amine catalyst is TMA.

12. A process for preparing a foundry shape, said process comprising the steps of: a) combining sand with part A of a binder system as defined in claim 1 ; b) adding part B of a binder system as defined in claim 1 to form a sand-binder mixture; c) blowing the mixture into a corebox; and d) contacting the mixture with a vaporized liquid amine catalyst composition in the corebox for a time sufficient to cure the resin.

13. The process of claim 10, further comprising removing excess catalyst composition and releasing the foundry shape from the corebox.

14. A catalyst composition for use in a cold-box system comprising TMA dissolved in a solvent.

15. The catalyst composition of claim 14 wherein the solvent is alcohol, water or a combination of alcohol and water.

16.The catalyst composition of claim 14, comprising about 5% to 30% TMA dissolved in solvent.

17. The catalyst composition of any one of claims 14 to 17 in a vaporized state.