Diver down (CP 2/2009)

BASF has offered products and solutions for cathodic e-coating for 30 years. CathoGuard coating systems provide dependable corrosion protection for metals and are very environmentally compatible.

Rust flakes: A thing of the past. E-coating makes car bodies more robust and resistant than ever before. (Picture: www.piqs.de)

 A cleaned and pre-treated car body is dipped into the bath. Air bubbles rise as it descends into the e-coat paint. After only a few minutes the body reemerges from the bath fully coated. Then after a rinse cycle it is dried in a curing oven.

Rust is now a thing of the past thanks to the anti-corrosion primer coat applied in the cathodic e-coating process. CathoGuard^® 800 and 900 represent the latest chapter in the success story of e-coating (see insert) that began over 40 years ago.

Opposites attract

Coating processes underwent fundamental changes in the early 1960s. Conventional dip coating was literally “electrified” through the introduction of anodic dip coating. In this process, a positive electric charge was applied to the car body, while a negative electric charge was applied to the paint.

This resulted in the paint bonding evenly with the car body, penetrating into even the smallest cavities. The electric dip coating process was highly effective for edges as well.

The even surface afforded by this coating technology provided an optimal substrate for the next paint layers. The uniform appearance achieved represented a refinement in surface quality. Since their invention, e-coating systems have steadily evolved to keep up with the constantly rising requirements of the automobile industry.

Resins play a major role in the process as bonding agents. “The resins ensure that the paint bonds with the car body under electrical current,” says Dr. Guenther Ott, a chemist and head of Resin Development for e-coats, who has worked uninterrupted for 30 years on the optimization of resins.

In the mid-1970s, anodic dip coating was replaced by cathodic e-coating. In cathodic e-coating, the poles are reversed. The workpiece is now negatively charged, and the paint positively charged.

At the end of the seventies, BASF supplied the paint for the first small parts e-coating line ever used in the European auto industry.

“We have been working successfully with Austrian carmaker MAGNA STEYR Fahrzeugtechnik and others for 30 years,” relates Guido Harbusch, a member of the BASF team serving the MAGNA STEYR Graz location.

The BASF Coatings plants in Münster and Guadalajara supply the required e-coat paints.

Ongoing: BASF chemists enhance the properties and eco-efficiency of acthodic e-coat paints. (Picutres: gettyimages)

New: Cathodic e-coating line at the MAGNA STEYR Fahrzeugtechnik plant in Graz, Austria. (Picture: MAGNA STEYR Fahrzeugtechnik)   The new generation In the late 1980s BASF introduced the CathoGuard technology. CathoGuard e-coat paints provide optimized edge protection, flow and throw power. CathoGuard 300 to 500 were the first lead-free cathodic e-coating product lines. The latest generations, CathoGuard 800 and 900, are also tin-free and conform to the latest environmental regulations.

BASF customers benefit from the environmental advantages of a solvent content of less than 1%.

CathoGuard 800 and 900 are HAP-free in line with US environmental regulations, containing no hazardous air pollutants. Though just now being launched, these product lines are blazing the trail to the future, anticipating new regulations requiring tin-free e-coat paints that are certain to be adopted sooner or later.

Especially integrated paint systems require a high degree of coverage of the various metal substrates – with CathoGuard technology this problem is solved.

“The success of cathodic e-coating as a technology is unparalleled,” says lab manager Dr. Klaus Arlt, who played a major role in the development of eco-efficient CathoGuard coatings.

“Cathodic e-coating saves a lot of material compared to conventional coating methods. The specified properties are in no way compromised, but rather enhanced, as the base polymers contained in the paint afford excellent corrosion and stone chip protection.”

And the low solvent content of modern dip coatings benefits the environment as well.

“And don’t forget our CathoCare^® services, available to all customers,” says Dr. Achim Gast, head of the BASF Coatings E-Coat & Primer Competence Center. CathoCare is a package of tools useful for a variety of applications ranging from planning to process monitoring.

“The service team works to optimize the production process. We provide on-site line operation support to ensure that customer processes run smoothly.” One core service is the regular analysis of e-coat bath samples taken from plants operated by car manufacturers and automotive suppliers. 

BASF Coatings manufactures cathodic e-coating products in Germany, Spain, Brazil, the US, China and India. All BASF Coatings production sites are equipped with product labs to test the paints produced for such properties as deposition behavior, stability and corrosion protection.

(Picture: gettyimages)

At these labs, product enhancements are studied for their adaptability to customer requirements while still in development. So experience, innovative spirit and customer focus are what makes BASF successful not only in cathodic e-coating.

www.basf-coatings.com