SAE International Organic/Inorganic Coatings Cured by Ultraviolet Light and Moisture for Automotive Glass 2012-01-1174

Ceramic enamel (frit) is an opaque, decorative border found along the periphery of glass windshields used in passenger and commercial transportation vehicles, as well as, architectural spandrel and decorative glass applications. In transportation and architectural applications, the primary function of ceramic enamel is to conceal aesthetically unpleasing, but essential structural components and to prevent photodegradation of the underlying polyurethane adhesive, which is used to bond glass windows into supporting structures. Typically, ceramic enamels are applied by screen printing ceramic slurry onto the glass substrate, which is subsequently fired in a furnace during the glass-forming process. The fired enamel is then primed with solvent-based primer(s) to facilitate adhesion between the enamel and polyurethane adhesive. Currently used ceramic enamels, and the associated processing and application of these materials for automotive glass bonding, have the following drawbacks: (i) high firing temperatures resulting in high energy costs, (ii) introduction of glass warpage and dimensional defects, (iii) volatile organic compound (VOC) emissions, and (iv) extra processing steps due to application of primer(s). As a result, a novel, organic frit has been developed to replace ceramic enamels that are commonly used in transportation glass applications. This organic coating crosslinks via exposure to ultraviolet (UV) light, and subsequently undergoes a secondary moisture-curing mechanism, via exposure to ambient moisture, to fully cure the coating as shown in Figure 1 . The resulting coating exhibits durable adhesion to both automotive float glass and polyurethane adhesives without the use of any primers. Moreover, the resulting performance of these novel coatings has been validated in both outdoor and accelerated weathering testing.