Patent ID: 8262955

Claim:
A process for making epoxy resin foam blocks of varying density comprising the following steps: (i) preparing a foam resin comprising: a first epoxy resin, a foaming agent to the extent of 2% to 10% of the mass of the epoxy resin, a surfactant to the extent of 2% to 6% of the mass of the epoxy resin, a filler, and a toughening agent, wherein the foam resin is made by the following steps: mixing the first epoxy resin and the foaming agent in a reaction chamber and stirring at a speed of about 500 rpm to form a homogeneous mixture; heating while stirring the homogeneous mixture to a temperature in the range of about 70° C. to 80° C.; increasing the speed of stirring to about 600-1000 rpm and temperature to about 120° C. to 180° C. to obtain a mixture containing froth; cooling the mixture containing the froth to a temperature in the range of about 15° C. to 30° C. and skimming off the froth to obtain a reaction resin; mixing said reaction resin with the surfactant, the filler and the toughening agent to obtain a mixture containing the reaction resin, the surfactant, the filler and the toughening agent; and stirring the mixture containing the reaction resin, the surfactant, the filler and the toughening agent at a speed of about 50-200 rpm to form a homogeneous foam resin; and (ii) preparing a curing agent comprising: a hardener and a second epoxy resin, and mixing together the foam resin and the curing agent, the ratio of the foam resin to curing agent being in the range of about 100:20 to 100:25 by mass to form a reaction mixture; pouring the reaction mixture inside a mold maintained at a temperature in the range of 70° C. to 80° C. and allowing the mixture to cure in the mold for 60 to 100 min.; allowing the mold to cool at a temperature in the range of 15° C. to 30° C. and demolding to obtain a green block; and post-curing the green block in an air circulatory oven for 10 to 15 hrs to obtain a final hard foam block.