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.

1 . Use of a blend of at least two tertiary amines as catalyst for curing a composite resin composition. 
   
   
       2 . Use according to  claim 1 , for curing a foundry shape by the cold box process. 
   
   
       3 . Use according to any of  claim 1  or  2 , 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. 
   
   
       4 . Use according to any of  claims 1  to  3 , 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. 
   
   
       5 . Use according to any of  claims 1  to  4 , wherein the amines are chosen from trimethylamine, N-methylaziridine, dimethylethylamine (DMEA), N-methylazetidine, N-ethylaziridine, diethylmethylamine (DEMA), dimethyl-isopropylamine (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, dimethyiheptylamines, methylethylhexylamines, diethylpentylamines, tripropylamines, N-pentylpyrrolidines, N-butylpiperidines, dimethyloctylamines, methylethyl heptylamines, diethylhexylamines, ethylpropylpentylamines, dipropylbutylamines and N-pentylpiperidines. 
   
   
       6 . Use according to any of  claims 1  to  5 , wherein the amines are chosen from DMEA, DMIPA, DEMA, DMPA and TEA. 
   
   
       7 . Use according to any of  claims 1  to  6 , wherein the blend of amines are chosen from DMEA-DMIPA, DMEA-DEMA, DMEA/DMPA and DMEA-TEA. 
   
   
       8 . Use according to any of  claims 1  to  7 , 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, is preferably 20/80 DMEA/DMIPA, 20/80 DMEA/TEA and 80/20 DMEA/TEA. 
   
   
       9 . Process for preparing a foundry shape by the cold box process, which process comprises the following steps:
 (a) forming a foundry mix with the binder and an aggregate,   (b) forming a foundry shape by introducing the foundry mix obtained from step (a) into a pattern,   (c) contacting the shaped foundry mix with a curing catalyst comprising a blend of at least two tertiary amines according to any of  claims 1  to  8 , in a liquid or preferably in a gaseous form, optionally with an inert carrier,   (d) hardening the aggregate-resins mix into a hard, solid, cured shape, and   (e) removing the hardened foundry shape of step (d) from the pattern.   
   
   
       10 . Process according to  claim 9 , wherein the inert gaseous carrier is nitrogen, air, and/or carbon dioxide. 
   
   
       11 . Process according to  claim 9  or  10 , wherein the curing catalyst system is a mixture comprising, in addition to the blend of at least two tertiary amines, up to 25%, preferably up to 10% and advantageously up to 0.5% by weight of at least another amine, primary and/or secondary. 
   
   
       12 . Process according to any of  claims 9  to  11 , wherein the curing catalyst system contains 0.2% by weight of water. 
   
   
       13 . Process according to any of  claims 9  to  12 , 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. 
   
   
       14 . Process according to any of  claims 9  to  13 , wherein the blend is chosen from DMEA-DMIPA, DMEA-DEMA, DMEA/DMPA and DMEA-TEA. 
   
   
       15 . Process according to any of  claims 9  to  13 , wherein the blend is 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 and 80/20 DMEA/TEA. 
   
   
       16 . Process for making a core or a mold comprising in addition to the process as defined in anyone of  claims 9  to  14  a further step of hardening the hardened foundry shape obtained from step (e). 
   
   
       17 . Process of casting a metal, characterised in that it comprises the following steps:
 a) preparing a foundry shape in accordance with anyone of  claims 9  to  15 ,   b) pouring said metal while in the liquid state into a round said shape;   c) allowing said metal to cool and solidify; and   d) then separating the molded article.