Three-dimensional printing

A method of forming a 3D printed polymer-particulate composite having a polymer-conductive agent composite portion and a polymer-fusing agent composite portion, the method comprising:

• (A) depositing a polymer build material;
• (B) selectively applying a non-conductive fusing agent including at least one non-conductive particulate and a conductive agent on the polymer build material, the conductive agent comprising:
• at least one conductive particulate present in an amount of from about 10% to about 60% of a total weight of the conductive agent;
• at least one co-solvent present in an amount of from about 10% to about 50% of a total weight of the conductive agent;
• water present in an amount of from about 0% to about 50% of a total weight of the conductive agent;
• and
• an additive present in an amount of from about 0% to about 10% of a total weight of the conductive agent, wherein a sum % of the at least one conductive particulate %, the co-solvent %, the water %, and the additive % equal 100% of the total weight of the conductive agent;
• (C) heating the polymer build material, the selectively applied conductive agent and the non-conductive fusing agent to a sintering temperature of from about 80° C. to about 450° C. to:
• (a) substantially removing at least the co-solvent, and
• (b) thermally binding:
• the polymer build material and the at least one conductive particulate;
• and
• the polymer build material and the at least one non-conductive particulate;
• and
• (D) completing (A), (B), and (C) at least one time to form a 3D printed polymer-particulate composite.

A three-dimensional printing composition comprising:

• a polymer build material;
• and
• a conductive agent including at least one conductive particulate dispensable onto the polymer build material to form a polymer-conductive agent composite portion of a 3D printed polymer-particulate composite when heated to a sintering temperature, the at least one conductive particulate present in an amount of from about 10 to about 60 weight percent of a total weight of the polymer-conductive agent composite portion,
• wherein the polymer build material is present in an amount of from about 5 to about 90 weight percent of the total weight of the polymer-conductive agent composite portion, and wherein the polymer-conductive agent composite portion has a hardness as measured in accordance with ASTM D2240 that is equal to or greater than a hardness of the polymer-fusing agent composite portion.