Paint & Coatings Industry - April 2008 - (Page 66)

High-Performance for Two-Component Waterborne T wo-component solventborne polyurethanes are the benchmark standard for high-performance coatings in the majority of coatings markets. For the formulator the advantages include: • wide formulation latitude due to the variety of coreactants and crosslinkers available; • high-quality appearance; • UV stability and weatherability using aliphatic polyisocyanates; • chemical and solvent resistance; and • hardness, flexibility, and toughness due to the urethane and urea linkages. However, there have been many market and legislative forces pushing formulators to consider waterborne systems. Traditionally, PUDs (polyure- FIGURE 1 | Standard hydrophobic polyisocyanate in polyol dispersion. thane dispersions) have been used to obtain the benefits of urethane properties in a waterborne system. These systems are dependant on hydrogen bonding, physical entanglement and coalescence to obtain their physical properties. Typically these thermoplastic systems have not been able to obtain the same high level of properties as a crosslinked 2K-solventborne system. One way to improve this situation was to use a polyisocyanate crosslinking agent. The first polyisocyanate crosslinkers were introduced in the early 1990s to much skepticism. Then and today, the challenge in waterborne systems is to effectively disperse a reactive system in water and retain highperformance properties. Due to ongoing research and development, properties of 2K-waterborne PUR coatings have constantly been improving. So today’s waterborne PUR systems show equal, or sometime even better, overall performance than comparable solventborne systems. Market/Performance Drivers From its introduction the market drivers for twocomponent waterborne PU systems have undergone a transformation. Initially the drivers were achieving low VOC, low odor, easy application and clean up. The uniqueness of this chemistry and the ability to meet these demands resulted in Bayer MaterialScience being awarded an EPA Green Chemistry Award in 2000. As the markets have matured higher demands have been placed on these systems and the challenges have been met by ever-improving systems. Most recently the dominant driver has been to match 2K-solventborne characteristics wherever possible. This has been seen most in areas requiring chemical and stain resistance, applications requiring fast drying characteristics, unique film properties like soft touch, and good adhesion to difficult substrates such as various plastics and wood. FIGURE 2 | Hydrophilic polyisocyanate in polyol dispersion. By Dr. Myron Shaffer | Bayer MaterialScience LLC, Pittsburgh, PA. 66 APRIL 2008 | W W W . P C I M A G . C O M http://WWW.PCIMAG.COM

Table of Contents Feed for the Digital Edition of Paint & Coatings Industry - April 2008

Paint & Coatings Industry - April 2008 Contents Viewpoint Industry News Calendar of Events Company News Mergers and Acquisitions Names in the News Snapshots of Success – Automotive Applications Designing UV-Curable Materials for High-Temperature Optical Fiber Applications The Future of UV Coatings is Now! Milling Media Review Part 1 – Bead Density Effect Preparation and Properties of UV-Curable Polyurethane Acrylate Resins for Metal Surfaces Conquering Color Harmony High-Performance PU Crosslinkers for Two-Component Waterborne Applications Decorative Film Laminates How Long Will the Gilding Glitter? Gaining a Competitive Advantage Using Benchmarking Supplier Showcase Materials Watch Products and Literature Classifieds Advertiser Index Automotive Color Trends New England Museum Solves Century-Old Vanderbilt Mansion Mystery

Paint & Coatings Industry - April 2008

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