3D Printing Conductive Plastics Without Melting Them

This patent describes a method for 3D printing objects and coatings from conductive plastics by mixing polymer and conductive fillers in a solid-state process, rather than melting them, to create parts that can conduct electricity or heat.

What it covers

This method creates conductive plastic parts or coatings using a process called solid-state additive manufacturing. It involves feeding at least one conductive solid filler (like carbon nanotubes or graphite) and at least one polymer or plastic through a hollow spindle or tool. This tool has a shoulder that rotates, applying normal, shear, and frictional forces. These forces cause the materials to deform plastically, meaning they change shape permanently without fully melting, entering a malleable or visco-elastic state. The materials are then deposited onto a substrate, forming a conductive 3D object or a coating, which can be electrically conductive, thermally conductive, or both, as described in claim 1 and 5. For example, it can create an anti-static coating (claim 8) or a coating for electromagnetic interference (EMI) shielding (claim 10).

What it doesn't cover

• —Does not cover traditional 3D printing methods that fully melt plastic filaments, like Fused Deposition Modeling (FDM) or Fused Filament Fabrication (FFF).
• —Does not cover additive manufacturing techniques that rely on liquid resins (SLA) or powder beds (SLS, binder jetting) without the specific solid-state deformation process.
• —Does not cover creating conductive plastic parts by simply mixing pre-made conductive plastic pellets and then melting them in a conventional injection molding process.
• —Does not cover methods that achieve conductivity by coating a non-conductive plastic part after it has been formed, rather than during the additive manufacturing process.
• —Does not cover processes that do not involve generating plastic deformation through normal, shear, and/or frictional forces from a rotating hollow spindle or tool.

The clever bit

The novelty lies in using solid-state additive manufacturing for plastics, which typically involves high heat and pressure but avoids full melting. This allows for compounding conductive fillers directly into the polymer during the printing process, creating a strong bond and precise control over conductivity, without the degradation that can occur with traditional melt-based methods.

Why it matters

Conductive plastics are essential for many modern technologies, from dissipating heat in electronics to shielding sensitive components from electromagnetic interference. This patent offers a way to precisely integrate these properties directly into 3D printed plastic parts or coatings. It also proposes methods for recycling plastic waste by mixing it with new materials or conductive fillers, which could reduce manufacturing costs and environmental impact.

Real-world examples

• 1.Heat sinks for small electronic components made from plastic
• 2.Anti-static enclosures for sensitive electronics
• 3.Electromagnetic interference (EMI) shielding for communication devices
• 4.Thermally conductive housings for LED lighting
• 5.Custom sensors or circuit traces embedded within plastic parts