Three-dimensional printing with pore promoting compounds

Abstract

The present disclosure describes kits and compositions for three dimensional printing, systems for three-dimensional printing, and methods of making three-dimensional printed articles. In one example, a multi-fluid kit for three-dimensional printing comprises: a fusing agent comprising water and a radiation absorber, wherein the radiation absorber absorbs radiation energy and converts the radiation energy to heat; and a pore-promoting agent comprising water and a water-soluble pore-promoting compound, wherein the pore promoting compound chemically reacts at an elevated temperature to generate a gas, and wherein the water-soluble pore-promoting compound is selected from the group consisting of sodium bicarbonate, potassium bicarbonate, and combinations thereof.

What is claimed is: 
     
         1 . A multi-fluid kit for three-dimensional printing comprising:
 a fusing agent comprising water and a radiation absorber, wherein the radiation absorber absorbs radiation energy and converts the radiation energy to heat; and   a pore-promoting agent comprising water and a water-soluble pore-promoting compound, wherein the pore-promoting compound chemically reacts at an elevated temperature to generate a gas, and wherein the water-soluble pore-promoting compound is selected from the group consisting of sodium bicarbonate, potassium bicarbonate, and combinations thereof.   
     
     
         2 . The multi-fluid kit of  claim 1 , wherein the pore-promoting compound is sodium bicarbonate. 
     
     
         3 . The multi-fluid kit of  claim 1 , wherein the pore-promoting compound is present in an amount from about 1 wt % to about 10 wt % with respect to the total weight of the pore-promoting agent. 
     
     
         4 . The multi-fluid kit of  claim 1 , wherein the elevated temperature at which the pore-promoting compound chemically reacts is from about 80° C. to about 200° C. 
     
     
         5 . The multi-fluid kit of  claim 1 , wherein the radiation absorber is a metal dithiolene complex, carbon black, a near-infrared absorbing dye, a near-infrared absorbing pigment, metal nanoparticles, a conjugated polymer, or a combination thereof. 
     
     
         6 . The multi-fluid kit of  claim 1 , further comprising a detailing agent comprising a detailing compound, wherein the detailing compound reduces a temperature of powder bed material onto which the detailing agent is applied. 
     
     
         7 . A three-dimensional printing kit comprising:
 a powder bed material comprising polymer particles;   a fusing agent comprising water and a radiation absorber to selectively apply to the powder bed material, wherein the radiation absorber absorbs radiation energy and converts the radiation energy to heat; and   a pore-promoting agent comprising water and a water-soluble pore-promoting compound, wherein the pore-promoting compound chemically reacts at an elevated temperature to generate a gas, and wherein the water-soluble pore-promoting compound is selected from the group consisting of sodium bicarbonate, potassium bicarbonate, and combinations thereof.   
     
     
         8 . The three-dimensional printing kit of  claim 7 , wherein the polymer particles have an average particle size from about 20 μm to about 100 μm and include polyamide-6, polyamide-9, polyamide-11, polyamide-12, polyamide-6,6, polyamide-6,12, polyethylene, thermoplastic polyurethane, thermoplastic polyamide, polypropylene, polyester, polycarbonate, polyether ketone, polyacrylate, polystyrene powder, wax, or a combination thereof. 
     
     
         9 . The three-dimensional printing kit of  claim 7 , wherein the pore-promoting compound is sodium bicarbonate. 
     
     
         10 . The three-dimensional printing kit of  claim 7 , wherein the radiation absorber is a metal dithiolene complex, carbon black, a near-infrared absorbing dye, a near-infrared absorbing pigment, metal nanoparticles, a conjugated polymer, or a combination thereof. 
     
     
         11 . The three-dimensional printing kit of  claim 7 , wherein the elevated temperature at which the pore-promoting compound chemically reacts is from about 80° C. to about 200° C. 
     
     
         12 . A method of three-dimensional printing comprising:
 iteratively applying individual build material layers of polymer particles to a powder bed;   based on a three-dimensional object model, selectively jetting a fusing agent onto the individual build material layers, wherein the fusing agent comprises water and a radiation absorber;   based on the three-dimensional object model selectively jetting a pore-promoting agent onto the individual build material layers, wherein the pore-promoting agent comprises water and a water-soluble pore-promoting compound, wherein the pore-promoting compound chemically reacts at an elevated temperature to generate a gas, and wherein the water-soluble pore-promoting compound is selected from the group consisting of sodium bicarbonate, potassium bicarbonate, and combinations thereof; and   exposing the powder bed to energy to selectively fuse the polymer particles in contact with the radiation absorber to form a fused polymer matrix at individual build material layers, thereby heating the pore-promoting compound to the elevated temperature to generate the gas distributed in the fused polymer matrix.   
     
     
         13 . The method of  claim 12 , wherein the pore-promoting compound is sodium bicarbonate. 
     
     
         14 . The method of  claim 12 , wherein the elevated temperature is from about 80° C. to about 200° C. 
     
     
         15 . The method of  claim 12 , wherein the gas forms isolated pores in the fused polymer matrix, the pores having an average diameter from about 0.1 micrometer to about 100 micrometers.