Solid polymer solution binders for shaping of finely-divided inert particles

A method of forming shaped parts from finely divided inert molding particles which comprises the steps of generally uniformly mixing said molding particles with a binder which comprises a minor fraction of at least one high molecular weight polymer and a major fraction of a low molecular weight chemical which is a crystalline solid at room temperature to form a mixture thereof, said mixing being carried out at a temperature at which at least said chemical of said binder is in a molten state, said polymer having a melting or fusion temperature at least as high as said chemical and being essentially soluble in said solid chemical when at least said chemical is in the molten state to form an essentially homogeneous solution and when such solution is cooled from such state below the melting temperature of said chemical solidifying without significant phase separation into an essentially homogeneous solid solution, said chemical being substantially non-volatile at its melting temperature and being soluble at a temperature below its melting temperature in a liquid solvent in which at least one said polymer is essentially insoluble;

• shaping said mixture while said binder remains in a molten state into a shaped part and allowing said binder to cool to below the of said part;
• and selectively and non-destructively essentially removing said low molecular weight chemical fraction of said binder from said part while at least one said polymer remains and creates a porous solid matrix holding said molding particles in said part shape by extracting at least substantially all of the solid chemical selectively of said polymer in a liquid solvent in which the chemical is soluble and said polymer is insoluble, said extraction being carried out at a temperature below the melting temperature of said solid chemical, whereby the shaped part remains rigid during the extraction and essentially faithfully retains its initial shape.