Granular material, granular material manufacturing method, three-dimensional laminated and shaped mold manufacturing apparatus, and three-dimensional laminated and shaped mold manufacturing method

A method for manufacturing a granular material for use in three-dimensional laminated mold shaping, comprising:

• forming a first material mixture by mixing a refractory granular raw material having an average grain size of 50 to 300 μm and an acid solution prepared by dissolving, in a solvent, an acid as a catalyst that activates and hardens an organic binder for binding the granular material;
• forming a second material mixture by adding and mixing magnesium sulfate in the first material mixture;
• and
• stirring the second material mixture, and immobilizing water molecules by a hydration reaction between the magnesium sulfate and the solvent of the acid solution, thereby forming a granular material for use in laminated mold shaping.

A method of manufacturing a three-dimensional laminated and shaped mold comprising:

• spreading a granular material into layers;
• selectively ejecting an organic binder to the spread granular material and hardening the organic binder so as to bind the spread granular material in accordance with a target three-dimensional laminated and shaped mold;
• and
• repeating said spreading step and said hardening step until the target three-dimensional laminated and shaped mold is shaped,
• wherein a coating material mixed with or coated with an acid as a catalyst that activates and hardens the organic binder for binding the granular material contains a material that causes a hydration reaction having a moisture absorbing function and generates a catalytic effect.