(496f) 3D Printed Tablets Using Binder Jetting and Pharmaceutical Excipients

Binder jetting is an additive manufacturing (AM) technology used to create three-dimensional model constructs. The materials used in binder jetting are relatively limited generally due to insufficient knowledge surrounding powder technology. The ability to self-formulate powder materials for use in binder jetting machines is not common practice today as not enough rigorous knowledge exists for the requirements of a 3D printable powder.

In this study we characterised several commercial 3D printable powders used in a 3DS Projet460 binder jetting printer, using techniques central to powder flow and powder wetting. The goal was to determine the key powder parameters that are likely to result in a successful binder jetting process, and then to use these parameters to screen standard pharmaceutical excipients for their likelihood to be suitable for 3D printing in a standard commercial printer.

Five different commercial binder jetting powders of various generations from different manufacturers were used as the benchmarks for a binder-jettable powder. Particle size and shape was measured using a Camsizer X2 and the powder flow (bulk and dynamic) was characterised using a Freeman FT4 powder rheometer. All five commercial powders had similar d₁₀ and d₅₀ values and similar shape distribution profiles. The FT4 showed that all powders fell within a narrow range for the parameters comprising basic flowable energy, specific energy, flow rate index and compressibility.

Drop penetration tests were used to determine the likely construct quality prior to the powder being 3D printed. The dried nuclei from these tests were analysed for spread, depth and hardness, which correlates to the dimensional accuracy of the powder after 3D printing. Drop penetration time seemed to have a wide range of acceptable values, but nuclei construct strength was important. A preliminary framework highlighting the quantitative parameters for binder jetting powders was created.

Finally, to test the framework approach, a simple formulation of 20% VA64 Kollidon and 80% Microcrystalline cellulose was used to successfully 3D print a range of basic tablet shapes in a Projet460 binder jet printer. The use of these commercial powders and characterisation techniques ultimately provide a useful benchmark for determining the suitability of standard pharmaceutical powder APIs and excipients to achieve good quality printed constructs, and sets out the considerations for specially engineered pharmaceutical particles and formulations that would need to be developed in future.