Curable coating compositions from emulsions of elastomeric polymers and polyurethane dispersions

#The present invention relates to a coating composition comprising a water continuous emulsion of a curable elastomeric polymer, an aqueous polyurethane dispersion, and an optional cure agent. The present invention further relates to a cured coating product formed from the composition.

#The use of airbags in motor vehicles has grown exponentially in recent years. Their use has expanded beyond frontal airbags for protection for the driver and passenger. Side airbags and inflatable curtains are now included in side compartments of vehicles for enhanced protection from side collisions or rollovers. This expanded use has placed new demands on the physical properties attributed to the airbags. In particular, improved air retention performance of airbags are desired to ensure the airbag remains inflated and maintains its integrity for an extended period of time upon deployment.

#Typically, airbags are made from synthetic fibers, such as a polyamide (nylon) or polyester and coated with a polymeric film. The most common polymeric materials currently being used to coat airbag fabrics are based on silicones, as described for example in U.S. Pat. No. 6,037,279. The silicone coating primarily provides a thermal barrier on the airbags to protect the fabric from the high temperature burst associated with ignition of the gas upon deployment. The silicone coating also provides some gas retention properties for the deployed airbag. One option to meet the increasing demand for gas retention is to increase the thickness of the silicone coating. However, newer designs for airbags, and in particular side impact airbags and inflatable curtains for side compartments, require airbags to have a more compact design. This results in a need for lower coating weights on the airbag fabrics. Furthermore, next generation side and inflatable curtain airbags have a need to retain pressured air/gas for sufficient time to provide rollover protection for greater than 5 seconds. Current silicone based coatings are too permeable to air/gas, especially at lower coat weights, to provide sufficient gas retention in deployed side and curtain airbags. Thus, there is a need for a fabric coating composition, and methods of application, to provide coated fabrics with sufficient air/gas retention for use in the construction of airbags, and in particular side and curtain airbags.

#The following examples are presented to further illustrate the compositions and methods of this invention, but are not to be construed as limiting the invention, which is delineated in the appended claims. All parts and percentages in the examples are on a weight basis and all measurements were obtained at about 23° C., unless indicated to the contrary.

#The particle size and profile of the formed emulsion coating compositions were evaluated using a MALVERN MASTERSIZER S (Malvern Instruments, Malvern, UK) equipped with 300RF mm range lens to detect particle size in the range 0.05 to 900 μm. The particle size profile indicates the stability and compatibility of mixture emulsion coatings. The particle size profile of an emulsion coating is reported using these three parameters: D(v, 0.5), D(v, 0.9) and span. D(v, 0.5) is referred as the average particle size and is the size of particle at which 50% of the sample is smaller and 50% is larger than this size. This value is also known as the mass medium diameter. D(v, 0.9) gives a size of particle for which 90% of the sample is below this size. Span is the measurement of the width of the particle size distribution and is the ratio of [D(v, 0.9)-D(v, 0.10)] to D(v, 0.5). No significant changes in the particle size were observed in these emulsion coatings.

#Materials