<p>Nonwovens are adaptable and cost-efficient materials. We are accustomed to seeing nonwovens in car interiors, as surface materials on hygiene products and as molded furniture, but they are often hidden from view in sound absorbents in dishwashers, as dust guards under spring mattresses and as fillers in clothing.</p>
Melt blown is a special technique for manufacturing nonwovens with very fine fibers, down to 0.5 μm. The fibers are elongated by blowing hot air at high speed concentrically along the fibers. The technique enables a wide selection of polymers, such as PP, PET, PBT and PLA, with a broad viscosity range. We can also mix in additives and modify the polymer, which provides virtually unlimited opportunities for ideas and approaches. Materials can even be produced with properties like those of a traditional spun bond.
The machine is designed for use in e.g. projects for air filters, medical technology products, sound absorbents, recycling and much more.
To calculate the production speed, a mass flow is needed that is dependent on the polymer type and viscosity, but for polypropylene it is 4.5 kg/hour, which corresponds to 1200 m/hour if the surface weight is 10 gsm. In other words, a few square meters of material can be rapidly produced.
To further modify and functionalize the surface of the fibers, our atmospheric plasma equipment can be used. There are many exciting opportunities here, such as making super hydrophobic surfaces or increasing dyeability.
Nonwovens are currently manufactured nearly exclusively of fossil-based raw materials, which is not long-term sustainable. By using solution blown, which is a technique similar to melt blown but where the polymers are dissolved instead of melted, it is possible to manufacture nonwovens also from renewable resources, such as cellulose.
The solution blown process starts from dissolving the polymer in a solvent, e.g. cellulose in ionic liquid. The solution is pumped through a spin nozzle where air is blown at high speed concentrically along each spun filament, which is elongated and collected on a drum in a coagulation bath. The technology is still at an early stage but much of the development that has already occurred in conventional wet spinning of cellulose can also be applied to the solution blown process. The aim is to be able to manufacture bio-based alternatives that can compete with for example, a spun bond of polypropylene.
RISE can offer to produce and develop nonwovens from both meltable and non-meltable polymers via the above mentioned techniques. We can also advise on different production methods for materials for various applications. Furthermore, additional components can be added at various stages in the process to provide the materials unique properties.
RISE can analyze nonwovens using a wide range of methods, including several of the methods that have been developed by the European trade organization EDANA. Moreover, we can handle most aspects of chemical analyses and examine the material with scanning electron microscopy (SEM).