Patent ID: 8186415

Claim:
A method for manufacturing a mold, comprising the steps of: (a) expanding a powder mixture containing a water-soluble inorganic salt powder and at least one water-soluble organic polymer powder selected from the group consisting of polyvinyl pyrrolidone, polyvinyl alcohol, polyethylene glycol and a cellulose derivative in a plane on a table to form a layer and then selectively spraying a spray liquid that is free of a binder component and contains at least one selected from the group consisting of a water-miscible organic solvent and water through a nozzle on this powder mixture layer to make a bonding strength among particles of the powder mixture layer in a sprayed region higher than that among particles of the powder mixture layer in an unsprayed region; (b) further expanding the powder mixture on the powder mixture layer after spraying and then selectively spraying the spray liquid through the nozzle on this powder mixture layer; (c) repeatedly conducting the step (b) over several times to form a mold shaped by the sprayed regions; and (d) taking out the mold.