Airbags for motor vehicles have become ubiquitous in passenger vehicles. These airbags are installed at strategic points in the passenger compartment of a vehicle and, in the event of a collision, are rapidly inflated with gas so that they act as an energy absorbing barrier between the vehicle occupant and an interior surface of the passenger compartment (e.g., steering wheel, dashboard, or windows). For example, side curtain airbags typically are installed within one or more of the pillars of the vehicle so that they provide protection during roll-over or side impact collisions. With the advent of such airbags, manufacturers began coating the airbag textile to modify the gas permeability of the textile, enabling the airbags manufactured from the textile to stay inflated for longer periods of time and provided the needed protection during the collision event.
There are many types of coating compositions used to produce such coated textiles, but one class of coating composition that is quite popular is a dispersion of a polymer in a suitable medium (e.g., aqueous medium). And while these dispersion-based systems are popular, they are not free from drawbacks and difficulties unlike solvent based systems.
Coatings for second impact or rollover side curtain application demand higher level of performance compared frontal airbags in that these curtains are required to hold gas for more than 5 seconds in a rollover event. High coat weights of silicone based elastomers are typically used in such applications where the costing weights range from 65 to 125 GSM. It has been shown that the coat weights can be reduced with high modulus coatings that can retain the performance after aging with careful selection of the material properties. In such examples, polyurethanes made from polycarbonate diol as the soft segment is needed in order to sustain the physical properties after aging. There have been other systems where the stiffness associated with polycarbonate based urethanes were overcome by making a hybrid polyurethane with two diols, namely a polycarbonate and a polyether. Even though the latter system meets the performance requirements, there remains a need to reduce the cost of the polyurethanes and also further improve the properties like stiffness, adhesion, etc.