| Résumé : |
The author explains the increased amount of environmental legislation impacting on anti-corrosion coatings.
Since the early days of epoxy chemistry, traditionaly type 1 / polyamidoamine systems have dominated the field of corrosion protection. A range of characteristics including tolerant mixing ratio, extremely long pot life, enhanced mechanical properties and relatively short drying times plus excellent corrosion prperties, has ensured the continued success of this solvent-based coating solution. However, increased legislative pressure surrounding the use of Volatile Organic Compounds (VOC) is driving forward significant changes in the global coatings industry. Formulators are being urged to reduce the use of solvents in coatig solutions to help minimise detrimental effects on the environment and human health. National authorities, especially in Europe and North America have established several solvent reduction programmes to ensure applicators reduce VOCs in their coating products (EU Directive 1993/12 and 2002/42; SCADQMD (South Coast Air Quality Management Discrit)) regulations for wood, metal and architectural coatings. Private companies and industry groups have also agreed to reduce VOC output by setting limits for production lines and evaluating alternative environmentally friendly technologies including power coatings and high solid coatings. These changes are impacting on heavy duty, marine, automotive, aerospace and architecture markets where 'green' solutions are becoming the technologies of choice, replacing traditional solventborne products such as the traditional type 1 / polyamidoamine systems.
An alternative option for coating formulators looking to reduce the use of VOC whitout compromising the level of corrosion protection provided is high solid systels. These are typically defined as a solution with a solid volume content grater than 60%. The reduction in solvent content in high solid coatings results in a higher thickness and viscosity, which can cause issued with spray coating applications. Therefore, for formulators to reach lower lovels of VOC and still have a fluid coating system, a lower viscous resin adn/or hardener is required. Here the resin and hardener options available for coating formulators looking to specify high solid, VOC-free coating systems and retain all the performance and application requirements for corrosion protection applications, are discussed. |
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Corrosion correctors in POLYMERS PAINT COLOUR JOURNAL - PPCJ, Vol. 198, N° 4522 (03/2008)
