| 摘要 |
In the preparation of foundry moulds and cores from foundry sand and a liquid furane, phenol-formaldehyde or urea-formaldehyde resin the curing catalyst used in powdered sodium bisulphate to which an amine has been added as a dust-inhibiting additive. The bisulphate may have a particle size or 50 to 500 microns. Specified amines are straight chain primary amines and amines R-NH-CH2-CH2-CH2-NH2 where R is C12- 18 alkyl. Exemplified powdered catalysts are mixtures of sodium bisulphate with (i) 1% oleylamine; (ii) 1% N-oleylpropylene diamine, 3.9% chromic oxide and 0.1% citronella; (i) and (iii) 1.5% N-lauryl propylene diamine and 2.5% isopropanol. In the specific Examples these are used with silica or sea sand, (mixed with 3 to 5% ball clay in Example 2) or zircon or chrome sand and 1 to 5% of resin. The catalyst is preferably mixed with the sand before adding the resin. |
