Commercial vehicles are exposed to all kinds of weather conditions: When used outdoors, especially their surfaces must be able to withstand harsh mechanical stress and dirt, as well as grit, frost, hail and UV rays. The vehicle’s surfaces must be well-protected for it to be able to function reliably in the long term. This calls for coating systems that provide a long-lasting effect against all external.
At the same time, demands on commercial vehicle surfaces are increasing: “The coatings of driver cabins nowadays are of nearly the same high quality as those in the automotive industry”, explains Georg Biber, industry sales manager at Emil Frei GmbH & Co. KG in Döggingen. “Many manufacturers are increasingly demanding that their vehicles, including all attachments, look as though they are produced from a single source. This means that a coating system must be able to work on various substrates – regardless of whether this concerns components made from steel, plastic or aluminium”.
For the most part, high-quality smooth sheet steel is used for the driver cabin, whereas attachments must often be blasted. Therefore, the differences in the coating structures are quite large: “The coating structure for the cabins usually consists of three layers: cathodic EC, filler and top coat. Attachments are often coated with only a corrosion protection primer and a top coat. The primer is subjected to a laborious and expensive intermediate grinding operation in order to achieve a consistent look”, explains Sascha Kollbeck, product developer for industrial coatings at FreiLacke. “However, several commercial vehicle manufacturers expressed a desire for the coating process steps to be reduced, if possible, while achieving an even higher degree of consistency with the cabin coating at the same time. The decision to begin by looking at the primer was unanimous. Our idea was to develop an epoxy primer with excellent filling properties to allow the intermediate grinding operation to be omitted, since it ultimately requires a high level of logistical effort and significant expenditure”.
Now, the system coating specialist from the Black Forest has supplied the market with an innovative coating system that renders the grinding step obsolete, and still achieves the highest level of surface quality : “The new, high-filling 2C epoxy resin primer FREOPOX primer ER1925 coats surfaces with blast depths of up to 50 μm very effectively in a single operation”, reports Renate Strohmayer, application engineer at FreiLacke. “With the elimination of the intermediate grinding operation and its laborious compressed air cleaning process, the customer saves between one and three hours of working time depending on the component.
In addition to its great filling properties, this primer produces an impressively smooth finish combined with – and despite – great durability properties, when applied in depths of up to 170 μm to perpendicular surfaces.”
In combination with another new development, the HighSolid 2C polyurethane EFDEDUR-HS top coat UR1449, brilliant and extremely smooth paintwork surfaces can now be produced. The coating structure is characterised by high brightness levels of up to 93 gloss units in a measuring angle of 60°, and up to 85 gloss units at a measuring angle of 20° on blasted steel with a surface roughness of 50 μm. “The high level of brilliance and the very good quality of application reduce the visual difference to the surface finish of the vehicle cab to a minimum”, explains Kollbeck.
Adding a surface coat of paint with High-Solid or Ultra-High-Solid EFDEDUR top coats can either take place after forced drying (30 minutes at 70 °C object temperature) or wet-in-wet after an intermediate ventilation time of 30 minutes in a standard climate.
The complete paintwork finish in the recommended layer thicknesses satisfies the corrosion protection requirements in accordance with DIN 12944 in Category C4 and is resistant to a large number of common operating materials. A high level of light and weather fastness is as obvious a requirement as a high level of cost-effectiveness.