Paint & Coatings Industry - November 2008 - (Page 56)

Highly Weather-Resistant Radiation-Curable Monomers and Oligomers for Exterior Applications FIGURE 5 | Backbone structure of monomers, alkane chemistry, CH2-R. Table 2 provides a list of monomers used in this study and their viscosities and surface tension. Hexane • Good heat resistance – Bond breakage @ 600 ºC • Good exterior durability – No chromophores – No oxidation – No UV degradation – Non yellowing FIGURE 6 | Q-TRAC testing. Air Tunnel (End View) Target Board Test Specimen Air Deflector Sun Sky Radiation • Hydrophobic – Non-polar hydrocarbon – Water hating • Chemical resistance – Stable structures • Adhesion promoting – Linear or planar carbon structure Tests Conducted Moisture and yellowing resistance were tested using two different types of test apparatus to attain accelerated laboratory results. These included the QUV and Q-SUN Xenon test chamber. Accelerated outdoor testing was also conducted through Q-TRAC testing in Arizona and actual outdoor weathering tests are still underway in Florida. These tests were conducted in accordance with the Automotive Test Method SAE J 1961-02, which is used to qualify exterior topcoats for automotive applications. Our reasoning was that if this harsh test method could be passed then the acrylated materials would be suitable for applications with less stringent requirements. The equipment, made by the Q-Panel Company, was used to conduct the weathering tests. The following describes each of the apparatus used along with the test conditions. A) QUV Testing- the conditions were: 8 hours of UV radiation @ 60 °C, followed by 4 hours dark condensation @ 40 °C. The lamps were replaced every 400 hours to ensure constant UV intensity. The bulb used was a UVA 340 from Q-Panel. The output is from 300 - 400 nanometers centered at 340 nm. This compares very favorably to natural sun light conditions. B) Q-SUN Xenon Test Chamber (Model 3100) equipped with humidity control to more closely replicate the high humidity conditions seen in Florida. The cycle conditions were as follows. 1) 40 minutes of light at 70 ºC (black panel temperature) -50% relative humidity. 2) 20 minutes of light and water spray. 3) 60 minutes of light at 70 ºC (black panel temperature) -50% relative humidity. 4) 60 minutes of darkness at 38 ºC (black panel temperature) - 95% relative humidity. C) Q-TRAC Testing – The sample to be tested is placed at the focal point of several mirrors, which collect the light and direct it to the test panel. This device then tracks the sun across the horizon, thus maximizing the sunlight exposure (Figure 6). D) Florida Exposure- Inland, facing South at a 5 degree angle. It was determined through empirical testing and observation that QUV testing is the harshest of the accelerated weathering methods. It is a good screening tool, as many samples can be tested at one time, and if a viable control sample is used, reliable results Center of Gravity and Rotation Flat Mirrors Mirror Bed FIGURE 7 | Gloss retention at 60° and yellowness index as a function of QUV exposure. 100 90 80 70 60 50 40 0 2 5 12 10 8 6 4 2 0 -2 0 % Gloss Retention Yellow Index 5700 2700 2200 1700 2200 2700 5700 1700 Film Thickness: 0.5 mil Film Thickness: 0.5 mil 8 12 16 20 24 28 Hours QUV X100 2 5 8 12 16 20 24 28 Hours of Exposure TABLE 2 | Monomeric diluents with excellent weathering resistance. Product # SR506 SR531 CD420 SR238 SR833S SR351 SR295 SR355 SR399 SR399LV Description IBOA Cyclic trimethylolpropane formal acrylate (CTFA) Acrylic monomer HDDA Tricyclodecane dimethanol diacrylate (TCDDA) TMPTA PETA Di-trimethylolpropane tetraacrylate Dipentaerythritol pentaacrylate Viscosity @ 25 ºC, cps 8 13 6 9 140 65 600 14,000 7,000 Surface Tension/ dynes 28.0 33.1 23.7 35.7 34.0 36.1 36.0 39.1 54 NOV EMBER 2008 | W W W . P C I M A G . C O M http://WWW.PCIMAG.COM

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Paint and Coatings Industry - November 2008 Contents Viewpoint Industry News Calendar of Events Company News Mergers and Acquisitions Names in the News HiTone Resins for Enhanced Pigment Affinity of Powder Coatings New Water-Based Interior Coatings Combine Innovation and Quality With Respect for the Environment Novel, UV-Curable Nanotechnology-Enabled Coatings Highly Weather-Resistant Radiation-Curable Monomers and Oligomers for Exterior Applications Konica Minolta — Sensing Success for Viracon Self-Crosslinkable Thermosetting Acrylics for Use in Water-Dilutable Coatings Paint and Criminal Forensic Science Supplier and Application/Curing Showcases Materials Watch Classifieds Advertiser Index

Paint & Coatings Industry - November 2008

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