Chemical company BASF estimates the size of the total market of materials for 3D-printing at around EUR 600m in 2015 and predicts a growth rate over 20% per year.
The firm’s global business director 3D printing in BASF new business Dirk Simon said: “Polyurethanes are currently only a small amount, however, the market need for thermoplastic polyurethanes (TPU) is obvious, because of their excellent property profiles, which are uniquely required in flexible parts.”
And for chemical firm Huntsman, it is the value from TPU properties that is driving its interest in the markets around 3D print.
Huntsman: Tentative entry
Huntsman Polyurethanes’ global marketing and technology director TPU Craig Roberts believes industry observers’ prediction that that 3D print is a potential industry disruptor “is probably right”.
“A football shoe cleat for example, has to be made of materials with properties that can perform as a cleat does."
Craig Roberts, Huntsman Polyurethanes
“The exceptional properties that you get from TPU – abrasion resistance, their elastomeric properties – means they can be used in dynamic applications that require flexibility and compression applications too,” he said.
From Huntsman’s point of view, said Roberts, the firm has various different production methods for TPU. He said: “We can affect the crystallinity and make a TPU behave like nylon 12 that melts sharply and re-solidifies at speed.
“You can almost make any formulation, as opposed to other plastics,” Roberts added.
He said that factors challenging Huntsman in its development of materials for 3D printing are “for example that the volumes are still quite small versus the number of grades.”
“If you are going from a prototype shape to creating something that has to perform, then it has to perform. A football shoe cleat for example, has to be made of material with properties that can perform as a cleat does.
“Whether our TPUs will be suitable for 3D printing, that’s something that we are looking at” but he added: “We believe TPUs will be used and the company is looking into that,” Roberts added.
Product customisation
“The movement is towards customisation. Whether it is shoes or cars, people want something different but also, it would be great if you could buy a shoe that was perfectly tailored to your feet. 3D print is a way of getting to that.
“The challenges include the high cost of the process and the relative slowness compared to traditional manufacturing methods.
"As for the potential, is it there today? No. Will it be there in ten years’ time? Well, we don’t know,” Roberts said.
At the firm’s K Show preview in Dusseldorf at the end of June, 2016, Roberts told delegates that TPU use in the 3D printing of custom-made shoes is now growing beyond the footwear industry into other application. “Areas,” he added, “where there is a need for functional parts with specific performance properties.
Part of the reason for the explosion of the interest in 3D print is due to the fact that the patents that protected the original inventions have expired.
Patent free potential
Covestro’s Dirk Achten, vp new applications EMEA, business unit coatings, adhesives and specialties, said he is excited by the new possibility for 3D print. “It has opened up from the rapid prototyping model it was two or three years ago.”
“What happened,” he said, “is that the technology’s basic patents expired. That was absolutely the key point and it was good and it was also bad.”
Covestro’s company line echoes Achten’s in that “after recognising the advantages of these additive manufacturing processes, industry now also views them as a major opportunity for efficient mass production of complex or individualised parts.”
However, while there are 3,000 materials available for conventional component manufacturing, only about 1% of those can be used for 3D printing, the firm revealed at a press conference in June.
The press conference also presented TPU as having “significant advantages over materials commonly used in Selective Laser Sintering, which tend to be less tough and elastic.”
Covestro has been developing systems SLA (Stereolithography), DLP (Digital Light Process) and inkjet printing. “These PU-based resins offer the unique opportunity to customise performance, due to the broad range of isocyanates and polyols from Covestro,” the firm said.
“Just imagine that you could scan and use clever software to analyse what’s required, and then you have a material process that automatically delivers a multi-material insole."
Covestro’s Dirk Achten
On the sidelines of the press conference, Achten told UTECH-polyurethane.com 3D printing will be a breakthrough because “in the future we will design products with a computer and the design that comes out of it is something that would not be possible by standard methodologies.
“From there you can go performance-driven and this for me is why it will change everything.”
“TPU is a very good starting point. If you look at the properties of TPUs, they are elastic, tough, they can be hard or soft. They basically have a huge spread of property levels.
“They tend to be used in high performance applications rather than super high temperature level applications,” he added.
Powdered products
The process converts TPU into a powder with a defined particle size through cryogenic grinding in one production process, said Achten. “You put a layer of the powder on a surface and then melt it selectively,” he added.
“After this comes the next layer, the same happens, and then the next layer and the next layer and so on. What you get is a bed full of powder and inside of the powder bed you can have multiple parts.
“So you can build multiple parts in one go and that is a beautiful process,” Achten said.
Engineer-driven technology
