| 摘要 |
<p>A thermosetting silicone resin used for coating starch (see Group V) may be in the form of a liquid having a low viscosity, e.g. from 10 to 20 centistokes at 25 DEG C., and may be diluted with a low-viscosity inert solvent, e.g. naphtha, petroleum ether, carbon tetrachloride or ethylene dichloride. From 1.4 to 3 per cent by weight of a catalyst, e.g. a zinc salt of octanoic or caprylic acid, may be added to the resin to accelerate setting. Linear polysiloxanes having the formula <FORM:0722771/IV (a)/1> may be used.ALSO:In making a free-flowing starch powder, starch particles, e.g of a size not larger than 50 microns, are coated, e.g. sprayed, with a thin film of a thermosetting silicone resin in an amount from 0.03 to 0.15, preferably from 0.06 to 0.10, per cent. of the weight of starch, and the coated particles are then heated to set the resin. The resin may be a liquid having a low viscosity, e.g. from 10 to 20 centistokes at 25 DEG C., which may be diluted with a low viscosity inert solvent, e.g. naphtha, petroleum ether, carbon tetrachloride or ethylene dichloride. From 1.4 to 3 per cent. of a catalyst, e.g. a zinc salt of octanoic or caprylic acid, may be added to the resin to accelerate setting. The coated particles may be heated until they contain less than 2 per cent. of moisture. The coated and heat-treated particles may be lubricated with from 0.05 to 0.10 per cent. of their weight of a dry, powdered, non-caking, non-hygroscopic, inorganic salt, e.g. magnesium carbonate or tricalcium phosphate.</p> |
