The Universal Selection Source:
Coatings Ingredients
Product News

Coil coating now even more environmentally and economically attractive

Published on 2006-08-01. Author : SpecialChem

MUNSTER -- The new, third generation of coil coating universal primers from BASF Coatings AG is suitable for every type of pre-treatment, is a significant improvement in terms of spreading rate and efficiency, and offers higher eco-efficiency. The first generation still required a chromate-containing pre-treatment. The second was introduced in 1995 and was one of the very early products designed with environmental protection in mind, being the first to enable chromate-free pre-treatment. The now-improved, chromate-free universal primer currently represents the optimum for the present technology standard. The homogeneous white system solution offers the ideal conditions for smooth and textured topcoats and does not just prevent the specter of rust on galvanized steel panels. It sets new records with regard to spreading rate, functionality, adhesion, flexibility and deep-drawability. Corrosion protection values determined using appropriate test methods exceed all previous results. The high-build process is also possible. The improved properties of the paint finishes can be demonstrated with the usual tests, such as the T-bend, tape or salt spray tests. In addition, BASF Coatings stored sample panels in climate chambers at 100 per cent humidity and 40 degrees for periods of many days. At the end of this there was not even a hint of rust. The chromate-free universal primer therefore also passed the weathering test specified by the construction industry, entailing 360 hours in a salt spray chamber, with flying colors. In this test, the permitted maximum corrosion creepback in artificially induced scratches is 2 mm. The new material - with 0 mm corrosion creepback - proved that it really is in a class of its own. The binder system at the heart of this is based on high-molecular polyester resins. BASF Coatings describes this as a combined corrosion protection concept which improves fundamental physical and chemical properties with consequential interdependence by means of new pigments and substances. Compared with the first generation, there has been a significant increase in the solids content and a corresponding reduction in solvents. The pigmentation itself is not only chromate-free, but also free of other heavy metals and carcinogenic substances. Although the environmental aspect in itself is of only marginal interest to the steel-coating companies - they all operate extremely effective after-burners - the peripheral effects (including higher coating speeds with increased quality stability) were probably the deciding factor in creating such strong demand.

Optimized universal primer for all pre-treatment types

Primers and topcoats form the functional basis for coil coating. Primers, applied directly to the cleaned, pre-treated strip, provide the necessary conditions for good adhesion of the topcoat systems and protect against corrosion. Universal primers, applied to the pre-treated metal, guarantee a number of important functionalities with their film thicknesses of approx. 5 µm, for instance adhesion for the topcoat, flexibility, deep-drawability, and reliable corrosion protection.Apart from their environmental compatibility, however, they can also play a significant role in increasing production efficiency. Rigorous refinements of a profitability-critical product therefore yield continual improvements.

The success of organically coated panels in white goods, the automotive industry and its suppliers, and in the construction industry is mainly based on the fact that the processor does not have to worry about either the coating process or the peripheral costs. These include: pre-treatment, waste water and exhaust air treatment, disposal of residues, investment and maintenance costs for the coating and drying systems, materials handling, logistics, energy management etc. Specialized steel mills handle these tasks inexpensively and efficiently. They use the coil coating method to apply paint systems with a range of surface textures to steel coils using rolls. This is carried out at speeds of up to 150 m/min and with exceptional quality. The actual coating itself is generally carried out on the top and bottom of the metal strip in a single pass. In 2-coat systems, the primer and topcoat are applied to the pre-treated metal substrate. Once the paint film has cured, at temperatures of between 200 and 250 degrees Celsius, the strips are rolled up again into large coils. Demands for more customized products designed for specific tasks and the different responses to the issue of chromate-free pre-treatment around the world have opened up approaches for further improvements in fields not limited to productivity aspects, logistics, and process management.

The greater acceptance of universal systems is understandable since, for example, a universal primer enables better product quality, reproducibility, and efficiency to be achieved on different lines than individual products. The target, therefore, was to produce a universal primer which (apart from the general exception with coil coating, i.e. plastisols) can meet both the economic andenvironmental demands when used as a basis for all topcoats and all pre-treatment types.

Source: BASF

ENG's TECHSCOUT 2018: Strategic Venturing & Innovation Excellence
Back to Top