3D printing offers freedom in design, enables existing functions of textiles and textile components to be optimized, and allows additional functions to be incorporated. Additive manufacturing, also known as 3D printing, is already being used in many different industries, including textiles. Until now, photocuring polymers or silicone have often been used for such applications.
However, polyurethane can also be used thanks to so-called “liquid additive manufacturing” (LAM). To this end, Wevo-Chemie GmbH, Ostfildern/Germany, has developed tailor-made reactive resins that improve both the processing conditions and the durability of the end products – from smart textiles to components for filtration technology or fuel cells.
In the LAM process, 2 reactive components are usually blended in a mixing and metering unit and applied directly to the textile to be printed by means of a print head. This step is performed without supporting structures. Wevo’s LAM products achieve the material properties necessary for the process by adding thixotropic additives to adjust the stability and the catalysts used to fine-tune the reaction times.
Moreover, no light source is needed to cure Wevo reactive resins, because the blend of resin and hardener components leads to the chemical reaction starting as soon as the mixture is dispensed by the print head. The exact curing time of the products – usually just a few minutes – is individually adjusted by adding catalysts. In addition, the time span can be shortened by using infrared (IR) lamps/IR heaters.
The chemical structures in polyurethanes are very similar to those in polyamide, polyester, polyacrylonitrile and elastane fibers. This results in the formation of hydrogen bonds, which ensure significantly better bonding of the material to the synthetic fibers compared with silicones. In addition, polyurethane wets the fibers well without penetrating them, making the textiles highly durable.