Production of low density products by additive manufacturing

Abstract

Provided herein according to some embodiments is polymerizable liquid useful for the production of a three-dimensional object by additive manufacturing, said polymerizable liquid comprising a mixture of: (a) at least one photopolymerizable component; (b) a photoinitiator; (c) at least one heat polymerizable component; and (d) heat expandable microspheres. A method of making a three-dimensional object from such a polymerizable liquid by additive manufacturing and objects so produced are also provided.

We claim: 
     
         1 . A polymerizable liquid useful for the production of a three-dimensional object by additive manufacturing, said polymerizable liquid comprising a mixture of:
 (a) at least one photopolymerizable component (e.g., in an amount of from 1 or 5 percent by weight to 90 or 98 percent by weight);   (b) a photoinitiator (e.g., in an amount of from 0.05 to 10 percent by weight);   (c) at least one heat polymerizable component (e.g., in an amount of from 2 or 5 percent by weight to 90 or 98 percent by weight); and   (d) heat expandable microspheres (e.g., in an amount of from 1 or 2 percent by weight, to 5 or 10 percent by weight, or more),   wherein said photopolymerizable component forms on photopolymerization a scaffold, which scaffold degrades on heating and optionally (but in some embodiments preferably) forms a degradation product that can polymerize with said at least one heat polymerizable component when heated and/or microwave irradiated.   
     
     
         2 . The liquid of  claim 1 , wherein said heat polymerizable component comprises at least one precursor to a polyurethane, polyurea, or copolymer thereof, a silicone resin, a cyanate ester resin, or a natural rubber. 
     
     
         3 . The liquid of  claim 1 , wherein said microspheres comprise a hollow thermally expandable shell (e.g., a thermoplastic polymer shell), and a propellant (e.g., a low-boiling point liquid or liquified gas such as a lower alkane), contained in said shell. 
     
     
         4 . The liquid of  claim 1 , wherein the at least one photopolymerizable component is present in an amount of from 1 percent by weight to 98 percent by weight; the photoinitiator is present in an amount of from 0.05 to 10 percent by weight; the at least one heat polymerizable component is present in an amount of from 2 percent by weight to 98 percent by weight; and
 the heat expandable microspheres are present in an amount of from 1 percent by weight, to 10 percent by weight.   
     
     
         5 . The liquid of  claim 1 , wherein said scaffold degrades on heating and forms a degradation product that can polymerize with said at least one heat polymerizable component when heated and/or microwave irradiated. 
     
     
         6 . The liquid of  claim 3 , wherein said shell comprise a thermoplastic polymer shell. 
     
     
         7 . The liquid of  claim 3 , wherein said shell comprises polyacrylonitrile, polyvinyl dichloride (PVDC), polyvinyl chloride (PVC), polyamide or polyacrylate. 
     
     
         8 . The liquid of  claim 3 , wherein the propellant is a low-boiling point liquid. 
     
     
         9 . The liquid of  claim 3 , wherein the propellant is a liquified gas. 
     
     
         10 . The liquid of  claim 9 , wherein the liquified gas comprises isobutane or isopentane. 
     
     
         11 . The liquid of  claim 1 , wherein said heat polymerizable component comprises at least one precursor to a polyurethane, polyurea, or copolymer thereof. 
     
     
         12 . The liquid of  claim 1 , wherein the polymerizable liquid is a flexible polyurethane resin. 
     
     
         13 . The liquid of  claim 1 , wherein the polymerizable liquid is an elastic polyurethane resin. 
     
     
         14 . The liquid of  claim 1 , wherein the polymerizable liquid further comprises a non-reactive pigment or dye that absorbs light. 
     
     
         15 . The liquid of  claim 1 , wherein the polymerizable liquid further comprises a reactive organic diluent.