Use of amine blends for foundry shaped cores and casting metals

Abstract

The present invention relates to an improved process for preparing foundry shapes by the cold box process, a process for making cores and moulds and a process for casting metals, carrying out as curing catalyst system a blend comprising at least two tertiary amines.

What is claimed is: 
     
         1 . A catalyst for curing a composite resin composition comprising a blend of at least two tertiary amines. 
     
     
         2 . Catalyst of  claim 1 , wherein each amine is present in the blend in an amount of not less than 10% by weight, and not more than 90% by weight. 
     
     
         3 . Catalyst of  claim 1  wherein the blend comprises at least one tertiary amine having 3 to 5 carbon atoms with at least one tertiary amine having 6 to 10 carbons. 
     
     
         4 . Catalyst of  claim 1 , wherein the amines are chosen from trimethylamine, N-methylaziridine, dimethylethylamine (DMEA), N-methylazetidine, N-ethylaziridine, diethylmethylamine (DEMA), dimethylisopropylamine (DMIPA), dimethyl-n-propylamine (DMPA), N-n-propylaziridine, N-iso-propylaziridine, N-ethylazetidine, N-methylpyrrolidine, N,N,N′,N′-tetramethyl diamino methane, triethylamine (TEA), methylethyl-n-propylamine, methylethyl-iso-propylamine, dimethyl-n-butylamine, dimethyl-sec-butylamine, dimethyl-iso-butylamine, dimethyl-tert-butylamine, N-ethylpyrrolidine, N-methylpiperidine, hexamethylene tetramine, dimethyl piperazine, N,N,N′,N′-tetramethyl diamino ethane, dimethylpentylamines, methylethylbutylamines, diethylpropylamines, dipropylmethylamines, N-propylpyrrolidines, N-ethylpiperidine, dimethyl hexylamines, methylethylpentylamines, diethylbutylamines, dipropylethylamines, N-butylpyrrolidines, N-propylpiperidines, diethyl piperazine, dimethylheptylamines, methylethylhexylamines, diethylpentylamines, tripropylamines, N-pentylpyrrolidines, N-butylpiperidines, dimethyloctylamines, methylethyl heptylamines, diethylhexylamines, ethylpropylpentylamines, dipropylbutylamines or N-pentylpiperidines. 
     
     
         5 . Catalyt of  claim 1 , wherein the amines are chosen from DMEA, DMIPA, DEMA, DMPA or TEA. 
     
     
         6 . Catalyst of  claim 1 , wherein the blend of amines are chosen from DMEA-DMIPA, DMEA-DEMA, DMEA/DMPA or DMEA-TEA. 
     
     
         7 . Catalyst of  claim 1 , wherein the blend of amines are chosen from 50/50 DMEA/DMIPA, 20/80 DMEA/DMIPA, 10/90 DMEA/DMIPA, 50/50 DMEA/DMPA, 20/80 DMEA/DMPA, 10/90 DMEA/DMPA, 50/50 DMEA/DEMA, 20/80 DMEA/DEMA, 10/90 DMEA/DEMA, 50/50 DMEA/TEA, 20/80 DMEA/TEA, 10/90 DMEA/TEA, 80/20 DMEA/TEA and 90/10 DMEA/TEA, preferably 20/80 DMEA/DMIPA, 20/80 DMEA/TEA or 80/20 DMEA/TEA. 
     
     
         8 . Process for preparing a foundry shape by the cold box process, which process comprises the following steps;
 (a) forming a foundry mix with a binder and an aggregate,   (b) forming a foundry shape by introducing the foundry mix obtained from step (a) into a pattern,   (c) contacting the foundry shape with a curing catalyst comprising a blend of at least two tertiary amines, in a liquid or a gaseous form, optionally with an inert carrier,   (d) hardening the foundry shape into a hard, solid, cured shape, and   (e) removing the hardened foundry shape of step (d) from the pattern.   
     
     
         9 . Process according to  claim 8 , wherein the inert carrier is gaseous and chosen from nitrogen, air, carbon dioxide or mixtures thereof. 
     
     
         10 . Process according to  claim 8 , wherein the curing catalyst further comprises up to 25% by weight of at least one additional primary and/or secondary amine. 
     
     
         11 . Process according to  claim 8 , wherein the curing catalyst further comprises 0.2% by weight of water. 
     
     
         12 . Process according to  claim 8 , wherein the blend is a mixture of at least one tertiary amine having 3 to 5 carbon atoms with at least one tertiary amine having 6 to 10 carbons. 
     
     
         13 . Process according to  claim 8 , wherein the blend is chosen from DMEA-DMIPA, DMEA-DEMA, DMEA/DMPA or DMEA-TEA. 
     
     
         14 . Process according to  claim 8 , wherein the blend is chosen from 50/50 DMEA/DMIPA, 20/80 DMEA/DMIPA, 10/90 DMEA/DM1PA, 50/50 DMEA/DMPA, 20/80 DMEA/DMPA, 10/90 DMEA/DMPA, 50/50 DMEA/DEMA, 20/80 DMEA/DEMA, 10/90 DMEA/DEMA, 50/50 DMEA/TEA, 20/80 DMEA/TEA, 10/90 DMEA/TEA, 80/20 DMEA/TEA and 90/10 DMEA/TEA, preferably 20/80 DMEA/DMIPA, 20/80 DMEA/TEA or 80/20 DMEA/TEA. 
     
     
         15 . Process of  claim 8  further comprising the step of hardening the hardened foundry shape obtained from step (e). 
     
     
         16 . Process of  claim 8  further comprising the steps:
 (f) pouring metal in the liquid state around said hardened foundry shape; 
 (g) allowing said metal to cool and solidify forming a mounded article; and 
 (h) separating the molded article and said harded foundry shape. 
 
     
     
         17 . Process according to  claim 8 , wherein the curing catalyst further comprises up to 10% by weight of at least one additional primary and/or secondary amine. 
     
     
         18 . Process according to  claim 8 , wherein the curing catalyst further comprises up to 0.5% by weight of at least one additional primary and/or secondary amine.