Respirators with Silicones
To effectively contain the transmission of the coronavirus, you need to know how it spreads. According to the Robert Koch Institute, Germany’s central scientific institution in the field of biomedicine, the SARS-CoV-2 is transmitted primarily through fine droplets in exhaled air. Blocking this route of transmission reliably is therefore important. A proven method is to wear appropriate protective masks.
Germany’s Federal Institute for Drugs and Medical Devices BfArM distinguishes between several types of masks. What are known as surgical masks, i.e., face masks, prevent the coronavirus from reaching other people when we exhale. Respirators, also known as FFP2 or FFP3 (filtering facepiece) masks, are even more effective, as they also protect the wearers themselves from infection. This makes them an indispensable component of the personal protective equipment needed for medical personnel and nursing services.
A Good, Comfortable Fit
In addition to the filter in a respirator, the body of the FFP mask also plays an important role. Because its edge surface sits directly on the face, it must mold to the contours of the face the entire time it is worn. For the mask to continue providing protection during use, virus-laden air should not be able to flow in or out through any gaps between the edge of the mask and the skin. Despite that, however, the mask should still be comfortable to wear.
No material is better suited to this task than silicone. Silicone rubber is permanently elastic and flexible, biocompatible and pleasant to wear. Silicone rubber also contains no plasticizers, and is long-lasting, resistant to wear and tear, and easy to sterilize. This makes it possible to reuse masks rather than immediately putting them in the trash after single use. In the era of COVID-19, that also helps prevent waste and improve sustainability in medicine.
Silicone is suitable for injection molding, which means that the masks can be made quickly, cost-effectively and in large quantities. WACKER’s ELASTOSIL® LR and SILPURAN® brands include a wide assortment of liquid silicone rubber grades for medical applications. These products meet biocompatibility requirements of the United States Pharmacopeia (USP Class VI) and of select tests described in ISO 10993.
Multifunctional, High-Tech Masks
When the coronavirus pandemic began, global demand for face masks and respirators rose dramatically within a very short period of time, and established manufacturers have still not managed to fully meet the immense need. Against this backdrop, companies that had been more at home in other industries up to that point began producing these kinds of masks as well. In order to secure supplies for hospitals, clinics and care facilities, the authorities greatly simplified approval processes.
This is what allowed Arburg, a machine manufacturing firm from southwest Germany, to design a multifunctional, high-tech mask and to set up its own production line – all on very short notice. The multi-purpose mask consists of a soft, elastic silicone piece placed over the mouth and nose. This piece fits inside a polypropylene shield with eyelets for attaching elastic straps and a central opening with a standard-size connection fitting. In principle, this design serves two functions:
- The basic version of the mask comes with a flow gate that can be closed to direct exhaled air downward protecting other persons from infection.
- Attaching a particle filter to the standard fitting, converts the mask into an FFP2 or FFP3 mask, depending on the filter selected. Configured in this way, the mask provides protection for the wearer as well.
For manufacturing the face mask, Arburg selected one of the highest-quality silicone rubber products currently available for applications like these: WACKER’s ELASTOSIL® LR 5040. The product is more than just soft and pleasing to the touch. Manufacturers that use ELASTOSIL® LR 5040 can also eliminate post-curing for many applications which saves time and energy. An official approval, which will officially allow the new multifunctional mask to be used as protective gear, is expected shortly.
WACKER's efforts against coronavirus
Arburg’s multi-purpose mask consists of a flexible silicone rubber mask (left) which is placed over the mouth and nose and a shield made of polypropylene (right). The mask was manufactured with WACKER’s liquid silicone rubber ELASTOSIL® LR 5040.