Paint & Coatings Industry - November 2008 - (Page 67)

Acrylics for Use in Coatings baked at 90 ºC for 30 minutes and the various optical, mechanical and chemical resistance properties of the cured films evaluated. In this work, the thermal curing and thermal degradation behavior of waterthinnable TSA resins were also studied by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) respectively. Experimental Materials • Acrylic acid: reagent purity-grade (E-Merck) was distilled under reduced pressure. • 2-Hydroxyethyl methacrylate: reagent purity grade (E-Merck) was distilled under reduced pressure. • Benzoyl peroxide: reagent purity-grade (E-Merck) was used as received. • Butanol: reagent purity-grade (E-Merck) was distilled under reduced pressure. • Ammonia solution (15% concentration in water): reagent purity-grade (S.D.fine) was used as received. Photo courtesy of Sico Paints. designations, along with the details of their formulation, are given in Table 2. Characterization Infrared spectra of the synthesized co-polymers (before neutralization) were recorded by using NaCl dies on a Perkin-Elmer 1750 FT-IR spectrophotometer. 1H NMR spectra were generated by an FT NMR system (Lambda JEOL JNM-LA400) and chemical shifts reported as (ppm) relative to tetramethyl silane. For DSC analysis, a universal V4.2E TA Instruments Q20 differential scanning calorimeter was used. The temperature range was kept as 20-200 °C, at the rate of 20 °C/min. The analysis was carried out on a 10 mg sample in an argon atmosphere at the rate of 40 ml/min. The thermal stability of TSA resin was measured by using a universal V4.2E TA Instruments Q50 thermogravimetric analyzer under TABLE 2 | TSA resin designations, formulations and characteristics of aqueous solution. Synthesis Copolymer synthesis was carried out by using various monomer mole ratios of (a) 1: 0.3 (b) 1:0.5 (c) 1:0.7 and (d) 1:1 as 2-hydroxyethyl methacrylate to acrylic acid respectively. The monomer-to-solvent ratio was kept as 40:60 (w/w). The benzoyl peroxide initiator concentration was 6.6% (w/w) to total monomer weight. The reaction setup, consisting of a three-necked round-bottom flask (capacity 500 ml) equipped with mechanical stirrer, thermometer pocket and water-cooled condenser, was used as the reactor for resin preparation. The flask was placed in a thermostatically controlled water bath held at 60 °C. After 1.5 hours, when the polymerization was completed, the solution was cooled to terminate the polymerization reaction, and neutralized with aqueous ammonia (15%, w/w) to a pH of 8.5 – 9.0 for making it water-soluble. The prepared water-soluble resinous material was separated by a separating funnel. Following this procedure and using different molar ratios of HEMA to AA, several other water-soluble TSA resins could also be prepared. The prepared resin S. Designation No. of Resin 1. 2. 3. 4. TSA1 TSA2 TSA3 TSA4 Formulation Monomers (mol) HEMA 1 1 1 1 Characteristics of Solution Solid content (% w/w) 31.4 31.7 32.1 32.3 AA 0.3 0.5 0.7 1.0 Viscosity at 25 °C (cp) 549.6 560.8 574.7 580.4 RI (at 25 °C) 1.4346 1.4450 1.4553 1.4653 PA I N T & C O A T I N G S I N D U S T R Y 65

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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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