Self curing moulding compsn. for casting moulds and cores - with refractory filler, aq. alkali silicate binder and propylene carbonate as hardener

摘要

Self curing moulding compsns. for casting moulds and cores consist of (a) a fire resistant filler, (b) an aq. soln. of an alkali metal silicate as binder and (c) propylene carbonate (I) as hardener. Pref. moulding materials contain 100 pts wt of a fire resistant filler, 2.0-7.0 pts wt of an aq. soln. of alkali metasilicate with a ratio SiO2:Me2O of 1.5-3.15 (Me2O = alkali metal oxide) and 0.1-1.0 pts wt (I). The compsn. may also contain 0.3-1.0 pts wt. of a foaming agent such as an alkyl sulphate and 0.5-5 pts wt dicalcium metasilicate. The (I) gives self curing compsns. which have the required pot life and curing times required for the industrial prodn. of casting moulds and cores.