Paint & Coatings Industry - November 2008 - (Page 36)

HiTone Resins owder coating manufacturers are increasingly searching for tools to improve their cost performance balance. Solutions that can lead to cost reductions are, for example, the use of higher filling levels, or applying thinner layers. However, such solutions could result in a decrease in properties like flow, gloss and hiding power. Using higher-level epoxies, flow additives and pigment additives can overcome these kinds of problems. On the other hand, it does cause adverse side effects and can lead to cost increase, yellowing and a decrease in powder stability. FIGURE 1 | Standard filled system compared to a highly filled system. for Enhanced Pigment Affinity of Powder Coatings P At higher pigment levels the appearance of powder coatings becomes worse. High pigment levels are required to reach a desired hiding power, especially in thin-layer applications. The difference in appearance between a standard and a highly filled system can be seen in Figure 1. Resins are developed based on a special concept, the HiTone concept, to overcome flow and appearance problems at higher pigment levels. The purpose of this study is to achieve a better pigment affinity of resins without compromising on important properties like flow, gloss and hiding power. As already mentioned, the pigment affinity can be improved by using the HiTone concept. This paper discusses the effect of the solution found on the properties of pigmented powder coatings. Besides the appearance, it is expected that the extrusion and milling behaviour of powder coatings with a higher pigment level will be affected. The effect of high-filled systems on milling behaviour is also discussed. Experimental A standard 70/30 hybrid resin and two 70/30 hybrid resins based on the HiTone concept (Uralac® P 770 and Uralac P 772) were synthesized. Uralac P 772 is a fastercuring version of Uralac P 770. Furthermore, a standard 60/40 hybrid resin and a 60/40 hybrid resin based on the HiTone concept (Uralac P 760) were synthesized. The properties of the 70/30 hybrid resins are given in Table 1, and the properties of the 60/40 resins are given in Table 2. The resins were tested in formulations with 33 and 50 wt% pigment. For these tests, TiO2 pigment (Kronos® 2310) was used. Typical 70/30 and 60/40 hybrid formulations of the 33 and 50 wt% pigment loaded systems are given in Table 3. Powder coatings were prepared by extrusion of the formulations using a Prism TSE 16 PC twin extruder TABLE 1 | Properties of the 70/30 hybrid resins. Standard 70/30 Hybrid Acid value (mg KOH/g resin) Viscosity (Pa.s) Tg (°C) 35 40 55 Uralac P 770 36 36 55 Uralac P 772 34 34 54 TABLE 2 | Properties of the 60/40 hybrid resins. Standard 60/40 Hybrid Acid value (mg KOH/g resin) Viscosity (Pa.s) Tg (°C) 53 25 58 Uralac P 760 54 24 58 By Jurjen Bolks, Stefan Brendeke, Eric Blokhuizen and Paul Vercoulen | DSM Powder Coating Resins, The Netherlands 34 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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