New PU dispersions for improved glass coatings

Bayer MaterialScience LLC has developed a one-component (1K) thermal-cure polyurethane coating to address the current requirements of glass decorators. These include:

• the ability to decorate and label over the cured Bayer coating,
• increased scratch resistance,
• the availability of a full palette of bright colors.

Furthermore, Bayer's 1K thermal-cure polyurethane coating cures at a lower temperature (therefore using less energy) and does not utilize heavy metals like cadmium. It is a more environmentally friendly option than ceramic coatings for items such as decorative tableware and flatglass, perfume bottles, and returnable and non-returnable bottles.

Dr. Raymond Stewart, senior scientist, Coatings, Adhesives & Specialties business development, Bayer MaterialScience LLC, discussed this and other advancements when he presented, "New Product Developments in Waterborne Polyurethane Organic Coatings for Glass" during the Society of Glass and Ceramic Decorated Products' Deco '12 show in Las Vegas.

During his presentation, Stewart explained that while Bayer's 1K thermal-cure polyurethane coating is an attractive alternative to ceramic coatings, glass decorators continually demand improved performance. To meet customer requests for coated glass containers that can be handled prior to curing, Bayer expanded on its previous technology and introduced a quick-dry, thermal-cure polyurethane coating.

Stewart detailed the formulation of this coating, which contains two waterborne polyurethane dispersions (PUDs) and a Bayhydur blocked polyisocyanate.

"The development of Bayer's quick-dry, thermal-cure polyurethane coating addresses a direct customer need," said Stewart. "Bayer strives to be on the cutting edge of raw material development, so we've utilized two PUDs to further expand the customization ability of coatings formulators."

Stewart explained that the uniqueness of Bayer's materials is in the composition of the hydroxyl functional PUD, blocked polyisocyanate and oxidatively curing PUD. Bayer provides formulating guidelines for quicker drying formulations that will still meet the industry's other performance requirements.

Not every customer desires the same coatings properties, so Bayer is providing the glass coating industry with options for customization. With the introduction of a new polyol into its Bayhydrol family of PUDs and a new blocked polyisocyanate into its Bayhydur PUD line, Bayer is meeting the ever-changing requirements of the glass coatings market. The choice of polyol and blocked polyisocyanate can affect the properties of the coating, so having more options from which to choose gives coatings formulators greater design freedom.