13 Congresso Internacional de Tintas 13ª Exposição Internacional de Fornecedores para Tintas

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1 HIGH PERFORMANCE ADDITIVES FOR WATER BASED AND LOW VOC PAINTS AND COATINGS Daniel de Moura Massarente, Wolfgang Geuking Croda Coatings and Polymers The replacement of solvent-based coatings by water based coatings and low concentration of volatile organic compounds is already a reality in the industrial and decorative paint market. Due to new governmental regulations and market awareness for consumer desire for green products and environmentally friendly coatings the demand for water based coatings will keep increasing in coming years. In this new scenario, the technological challenges for the change of solvent based coatings to water based coatings are increasing as well. To ensure the same level of quality and performance requirements, such as good adhesion and water resistance while being resistant to scrub, washability, chemicals, corrosion and weather are the main challenges of the paints and coatings formulators. This paper aims to present the technological solutions that collaborated with the entire value chain of the paints and coatings industry, to ensure that this increased demand for water-based and low concentrations of VOCs coatings can be achieved with excellence by producers of acrylic polymers, alkyd resins and also by paint formulators. Next pages will presented solutions for polymers, paints and coatings based on waterborne and solvent-borne with a low concentration of volatile organic compounds (VOC). NON-MIGRATORY SURFACTANTS IN EMULSION POLYMERIZATION Surfactants that form covalent bonds with the polymer during polymerization and significantly improves the final properties of the emulsion polymers. The anionic NMS: is a phosphate ester functional modified alcohol ethoxylate. Water solubility is varied with EO-chain length of the hydrophilic part. The nonionic NMS: is an alkenyl functional ethoxylate. Figure 1. Schematic structures of non-migratory surfactants

2 Figure 2. Polymeric film contaminated with conventional surfactant (NP30) after contact with water Figure 3. Polymer film with a nonionic surfactant and non-migratory after contact with water The technology of non-migratory surfactants gives colloidal stability, resistance to shear and freezing, and greater compatibility with pigments and solvents. While traditional surfactants bring some disadvantages, as increasing sensitivity to water and affect the properties of gloss and adhesion of the final coating, reactive surfactants provide superior dry film properties such as: Maintenance of brightness Barrier to water Increased Adherence Greater scrub resistance

3 Figure 4. Comparison of the appearance of film in a market high gloss paint Vac / BA and a high gloss paint Vac / BA containing surfactants non-migratory ADVANCED SURFACTANT TECHNOLOGY FOR ALKYDEMULSIONS FOR VOC FREE COATINGS A new generation of polymeric surfactants that allow the development of alkyd resins emulsified in water with excellent stability and free of tack, without compromising the performance of paints and coating. One way to produce paints more benign with low levels of VOC's, or even 0% VOC, is the transformation of enamels solvent based (alkyd) in alkyd emulsions based on water. This can be done by effective emulsifiers, which do not affect film properties of the final paint and also provide a stable emulsion that allows production of paints for a shelf life of two years. Figure 5. Manufacturing process of alkyd emulsions water base GLOSS º 60º Figure 6. High gloss enamel paint

4 Figure 7. Particle size stable during the stability tests with and without temperature Figure 8. Particle size stable during the stability tests after one month at 50 C MULTIFUNCTIONAL WETTING AGENTS FOR WATER BASED COATINGS The current regulatory environment and consumer trends toward environmentally friendly products have increased the need to formulate aqueous coatings. One of the issues formulators face is the use of more additives in water borne systems than in similar solvent borne coatings. Multifunctional additives successfully solve this issue. Multifunctional additives combine and maximize capabilities of other additives, as, wetting aid and a pigment dispersant, a surface tension reducer for clean and for unprepared substrates, or a low energy substrate wetter and a deformer.

5 Figure 9: Wetting of Multiwet wetting agents, two competitive products and water on clean (washed) black nylon Figure 10: Wetting evaluations on unprepared (unwashed) black nylon Figure 11: Color strength of Multiwet SO compared to competitive material in a 2% dispersion in a clear base with 40% blue 15.4

6 Figure 12: Color development of Multiwet SO compared to competitive material Figure 13: Foam level of Multiwet products Figure 14: VOC and biodegradability of Multiwet products CORROSION INHIBITORS FOR WATERBORNE COATINGS The use of inhibitors becomes necessary in order to avoid chemical degradation, ensuring safety and appearance of metallic substrates. A good corrosion inhibitor for use in painting barrier should not interact with other components of a paint formulation, so it must be sufficiently inert so as not to interfere with film forming properties, stability and rheology of the formulation. Corrosion inhibitors based on organometallic esters, optimized especially for water based coatings gives excellent results against flash rust and corrosion protection in the long term. The corrosion inhibitor which is presented here contains no VOC and is free of HAP substances (Hazardous Air Pollutant).

7 13 Congresso Internacional de Tintas Control paint for direct to metal Control paint for direct to metal + 2% corrosion inhibitor based in aromatic acid Control paint for direct to metal + 2% corrosion inhibitor based organometallic esters Figure 15: Results of Flash rust tests after one hour Primer formulation with traditional corrosion inhibitors Primer formulation with corrosion inhibitors based on esters organometallic Figure 16: Unscribed DTM primer spray-applied panels after 500 hours 5% salt fog exposure

8 POLYMERIC SURFACTANT W/O STABILISER The decorative paint industry is challenging formulators to develop costeffective, high performing decorative paints with reduced solvent levels. The use of solvent borne alkyd based paints will not be phased out in short, but legislator and consumer expect the paint formulator to offer formulations with significantly less VOC s. The technology water-in-oil (W / O) must meet targets low VOC without sacrificing performance. The water is formulated as a liquid load in a solvent-based paint and replaces partly the solvent. The formulation stability is ensured with the aid of polymeric surfactant. The solvent-based alkyd resins can be formulated with a competitive cost, high quality and in accordance with regulations for VOC paints and varnishes. Short drying times are achieved by controlling the thickness of the dry film without increasing viscosity over storage time. Adding water in solvent-based market paint 1 (440 g / l VOC): Brookfield viscosity (DV-II, 30rpm, spindle 18 Ambient) BK dry time (ASTM 5895), hrs 1) Sikkens Cetol TGL Plus 20% water 10% water mpa.s % water % water 10% water 20% water Visco 24hrs RT Visco 1 week RT Visco 1 w eek 50 C leveling basic trace ripple surface trace Figure 17: Influence of the water in oil emulsion in viscosity and drying time Adding water in solvent-based market paint 2 (300 g/l VOC) Figure 18: Influence of the water in oil emulsion in viscosity and drying time

9 CONCLUSION Using the most advanced technologies available on the market is possible to formulated resins, paints and coatings that meet the new requirements and market needs, regarding safety and environmentally friendly products. Additives presented in this study allow the partial or total replacement of traditional solvents by water, reducing the levels of VOC with equal or better performance in various applications of paints and coatings.