Synthetic stone, esp. for mfg. toy building bricks etc. - where dry mixt. contg. gypsum, expanded clay, mineral and pigment, is made into aq. slurry and moulded to shape

摘要

A mixt. is made contg. gypsum, expanded clay, milled porous mineral, metal oxide pigment, and an accelerator. Water is then added to the mixt. to make a slurry, which is pored into moulds and set or hardened. The pref. mixt. contains (all pts. wt) 100 gypsum; 22.9 light expanded clay of size 0.01-2.0 mm; 2.9 milled perlite, size 1-3mm; 0.58 TiO2; and 0.76 accelerator. The setting time of the aq slurry is pref varied by adding an organic or inorganic hardener either to the dry mixt or to the water, and/or by altering the temp of the slurry. Conventional toy building bricks etc are made out of baked clay like normal bricks, and thus involve many mfg. steps and result in heavy toy bricks, which are difficult to machine. The invention provides toy bricks of low wt. and good machineability.