Three-dimensional (3d) printing

Abstract

In a three-dimensional printing method example, a pre-treatment coating is formed on a part precursor by applying and drying, alternatingly: a polycation solution including a chloride ion and a polyanion solution including a sodium ion to form at least two layers. An ink is selectively deposited on the pre-treatment coating.

What is claimed is: 
     
         1 . A three-dimensional (3D) printing method, comprising:
 forming a pre-treatment coating on a build material by applying and drying, alternatingly: i) a polycation solution including a chloride ion and ii) a polyanion solution including a sodium ion to form at least two layers;   selectively depositing an ink on the pre-treatment coating; and   exposing at least a portion of the build material having the pre-treatment coating and ink thereon to electromagnetic radiation to form a pre-treated part.   
     
     
         2 . The 3D printing method as defined in  claim 1  wherein:
 the ink is a fusing agent; 
 all of the build material is exposed to the electromagnetic radiation; and 
 an area of the build material in proximity of the fusing agent fuses to form the pre-treated part. 
 
     
     
         3 . The 3D printing method as defined in  claim 1  wherein the at least the portion of the build material is selectively exposed to the electromagnetic radiation and sinters to form the pre-treated part. 
     
     
         4 . The 3D printing method as defined in  claim 1  wherein:
 the polycation solution including the chloride ion is selected from the group consisting of a primary amine hydrochloride and a secondary amine hydrochloride; and 
 the polyanion solution including the sodium ion is selected from the group consisting of a sodium carboxylate, a sodium sulfonate, and a sodium phosphonate. 
 
     
     
         5 . The 3D printing method as defined in  claim 1  wherein the ink is a conductive ink. 
     
     
         6 . The 3D printing method as defined in  claim 1  wherein the applying of the polycation solution and the applying of the polyanion solution are accomplished by thermal inkjet printing, piezo electric inkjet printing, dip coating, painting, or spray coating. 
     
     
         7 . A three-dimensional part, comprising:
 a sintered or fused substrate;   a multi-layer pre-treatment coating on the sintered or fused substrate, the multi-layer pre-treatment coating including:
 a polycation layer; and 
 a polyanion layer; and 
   an ink applied to at least a portion of the multi-layer pre-treatment coating.   
     
     
         8 . The three-dimensional part as defined in  claim 7  wherein:
 the polycation layer is formed of poly(allylamine)hydrochloride; and 
 the polyanion layer is formed of poly(sodium 4-styrenesulfonate). 
 
     
     
         9 . The three-dimensional part as defined in  claim 7  wherein the ink is a conductive ink and forms a conductive element.