A broad application of polymer 3D printing for industry especially mass production has been hindered mainly by the slow printing speed and limited choice of suitable materials. Carbon’s CLIP  (Continuous Liquid Interface Production) technology allows a tremendously faster printing speed by using UV light and oxygen to control the polymerization of liquid resins. Compared to polymer 3D printing techniques such as sintering of powders or thermal extrusion and fusion of polymer filaments, in both of which commercially available thermoplastics are used, 3D printing of photopolymers are mainly for prototyping or areas that do not demand strong mechanical properties since the resulting photopolymers are brittle, weak, and not versatile. It is still intriguing, yet also challenging to find a way to produce 3D printing photopolymers that can match properties of conventional thermoplastics, because either sintering or the thermal fusion method cannot really produce mechanically-isotropic, solid parts resulting in inferior mechanical properties due to the porous and layer-bearing nature of part compared to the injection molded counterparts. We developed a dual-cure chemistry for the CLIP technology, that uses UV light to shape the part while using heat to trigger a secondary reaction blended within the formulation, thus creating materials having a wide range of great properties similar to conventional thermoplastics, with unprecedented benefit of speed and surface finish. In the case of elastomers, we grew high molecular weight polyurethane/urea within a UV network by thermally triggering the reaction between blocked isocyanate and a diamine chain extender. The isocyanate blocking molecule was chosen to also have a UV curable functionality in order to provide sufficient green strength during the printing process in addition to ensuring good pot life of resin. Using such chemistry, we created a durable, resilient elastomer that is being mass-produced for the adidas’ FutureCraft 4D midsoles.

Durable, resilient elastomers fabricated by light: The power of dual cure in 3D printing

256th National Meeting (2018)

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