3D Printing is creating a revolution in manufacturing, taking it to the next paradigm, says our columnist in this issue. It has several advantages over conventional manufacturing and is expected to impact every industry. The chemical industry will be both, a provider of new generation materials needed for 3D printing as well as a beneficiary of this process.
3D printing is doing to manufacturing what Gutenberg’s printing press did to knowledge in the 15th Century – democratisation. 3D printing, or Additive Manufacturing (AM), creates products with superior features and performance. It allows for easy customisation of products at almost no extra cost. It can create spare parts on demand. It reduces material wastage. It allows complex geometries to be made in single piece. With advantages like these, there is practically no industry that would be left untouched by 3D printing. And there is virtually nothing that cannot be 3D printed; even body parts! The market for 3D printing is expected to grow globally to $63 billion by 2026 at a CAGR of 23.7%.
The chemical industry is expected to play a very significant role in the explosive growth of 3D printing business. Last month, two global giants of the chemical industry – BASF and DuPont – launched new materials for feeding 3D printers, thereby forging strategic alliances with the rapidly burgeoning 3D printing business. DuPont has introduced several high performance materials in filament form which can be used as raw materials by 3D printers. These are polyamides reinforced with glass or carbon fibres and combine lightweight with excellent heat and chemical resistance.
BASF has launched special photopolymers suitable for 3D printing. The company claims that these polymers offer better mechanical properties and longer stability than materials presently available. Going a step further, BASF has also entered into tie-ups with 3D printer manufacturers, seeking synergy between material expertise and 3D printing software. Availability of such new materials is an important step to meet the demands of component manufacturers who are seeking 3D printing materials with similar mechanical and chemical properties as well-known injection moulding polymers.
Materials
Providing innovative feedstock for 3D printing offers a tremendous opportunity for the chemical industry. BASF and DuPont are just two of the several chemical companies making a beeline before the fast maturing 3D printing industry, which is now demanding materials that are superior to conventional supplies. Thermoplastic resins, thermoplastic filaments, photosensitive resins, metal powders, metal wires and ceramic powders are some of the most commonly used raw materials for 3D printing. Polymers are the most widely used feedstock in 3D printers; ABS, Polylactic Acid (PLA) and Polyamides being the most common.
Covestro, a global leader in polymers, is developing a range of filaments to feed 3D printers. 3M has filed a patent for using fluorinated polymers in 3D printing. Wacker is working with silicones for 3D printing. Evonik has announced the development of Polyether Ether Ketone (PEEK) based filament for 3D printing of medical implants in human body. Arkema, Clariant, Mitsubishi, SABIC and Solvay are among others who have joined the 3D printing bandwagon. All of them are making serious investments in creating new materials for 3D printing.
Thermosetting, photopolymers constitute a lion’s share of the market for 3D printing materials because of their superior mechanical stability at high temperatures and excellent chemical resistance. However these 3D printed parts are inherently non-recyclable due to their permanent crosslinks. A new thermosetting vitrimer epoxy ink has been developed that makes it possible to recycle parts printed from it.
Unlike thermoplastics and metals, ceramics pose special challenges for 3D printing. Conventional ceramic materials contain resin and parts printed using these materials can shrink as much as 20% during the post-annealing process. Canon, the Japanese camera and digital printing specialist, has developed proprietary ceramic powder formulations that limit the shrinkage to as low as 0.8% while printing objects with complex geometries such as honeycomb structures. This concept of bundling the printer with proprietary formulations could very well be the start of a new business model for the chemical industry.
Methods
During the 3D printing process, solid material changes into molten state and again back to the solid state. The rate at which this transformation takes place influences the microstructure of the printed part, which in turn affects the macro-properties. The printing technique plays an important role in the properties of the final product.
There are several methods of 3D printing. Fused Deposition Modelling (FDM) is the most popular method and is used for building proof-of-concept models. FDM 3D printers build parts by melting and extruding thermoplastic filaments which is then deposited layer by layer. FDM uses a range of thermoplastics like ABS, PLA, etc.
Stereolithography (SLA), the first 3D printing method to be invented and patented in 1986 by an American, Charles Hull, uses photopolymerisation in which laser is used to cure liquid resin into hardened plastic. Among all 3D printing techniques, SLA provides the highest resolution, clearest details and smoothest surface finish. SLA is used to manufacture prototypes that require tight tolerances and smooth surfaces. Material manufacturers are creating innovative SLA resin formulations with mechanical, thermal and optical properties that rival the best engineering thermoplastics.
Selective Laser Sintering (SLS) uses a high powered laser to fuse polymer powder particles, and is the most commonly used technology for industrial applications. The most commonly used material for SLS printing is Nylon. Parts produced by SLS printing have excellent mechanical properties with strength resembling that of injection moulded parts.
New 3D printing technologies are continuously emerging from different laboratories. A research institute in Germany has developed Cold Plasma Jetting method to print plastic bone implants. New generation of 3D printers are able to accommodate a wider variety of feedstocks.
Bespoke Reactors
3D printing is also touching the chemical industry in an entirely different way. It is taking chemical synthesis into an exciting new realm that few could have imagined. In January this year, scientists at the University of Glasgow built a polypropylene reactor using 3D printing and deployed it to synthesise Baclofen, a muscle relaxant. In a far-reaching proof of concept work, the team was able to carry out multiple reactions, liquid-liquid extractions, evaporation and filtration in this micro-reactor module and produce Baclofen Hydrochloride as a white powder. Such bespoke reactors have numerous applications; for example it will allow synthesis of specialty molecules with short shelf life as and when needed. It can be used to make unique drugs on demand for just a small number of people who need them.
Loughborough University in UK uses 3D printed chemical reactors with embedded sensors to design experiments for studying and optimising reactions that use novel chemistries. 3D printing will enable accurate fabrication of geometries optimised through Computational Fluid Dynamics. This will help in fabrication of special reactors and structured catalysts.
3D printing is a wonderful confluence of Chemistry, Material Science and Computer-aided Design and Fabrication to create a brave new world.
Readers’ responses may be sent to: k.sahasranaman@gmail.com or chemindigest@gmail.com
