Lower costs, reduced air pollution, and better performance continue to be key drivers in automotive coatings, but getting car companies to adopt wholesale change can be a slow process. Some are willing to totally transform the painting process to achieve these goals; for those that aren't, the auto paint industry has more modest alternatives as well.

The color of a car is one of its important selling features, so it should come as no surprise that automakers fret over the performance of their multilayer coatings. First, there is an electrodeposition layer put on the steel. Then, a primer surfacer is applied, followed by the colored base coat and then the clear coat, which protects the whole paint job from the elements.

"In the automotive area, aesthetics are key," says John Martin, a consultant with Tiax, formerly Arthur D. Little's technology innovation business. "You have to have a 10-year life, and the finish has to look exquisite."

Like many other businesses, the auto industry is torn between trying to reduce costs on the one hand and, on the other, dealing with the high price of performance-enhancing technology and environmental compliance--notably meeting ever-tightening regulations on volatile organic compounds in paints.

Thus, while automakers pay attention to environmentally friendly technologies like waterborne and powder coatings, they are often reluctant to actually drop their solvent-based coatings because of the cost of switching or performance drawbacks. "On environmental issues, people will say they want the best performing products and the greenest product possible," Martin says, "but when push comes to shove, if there is a less expensive alternative that meets less stringent regulations, people are going to be very conservative about making choices."

Sales and volume figures reflect a gradual shift to higher performing auto paints. The global market for automotive paint was $6.6 billion in 2001, according to Phil G. Phillips, president of the Southern Pines, N.C.-based consultancy PG Phillips & Associates. North America accounted for $2.5 billion of this.

THE VALUE OF the North American auto paint market is growing by 1% annually over the rate of new car production while the volume is shrinking by 0.5% a year. The volume decline, Phillips says, stems from a combination of increasingly efficient painting equipment and increasing levels of solids in paint, which decreases the volume of paint that needs to be applied.

In the past five years, Phillips adds, the average level of solids in automotive paints has increased from about 38% to 47%. He thinks this level will approach 60% in another five years.

This has been the long-term trend. Carl Weber, BASF's North American marketing director for automotive OEM (original equipment manufacturer) coatings, notes that 30 years ago when lacquer-based paints were still being used, "80% of what was sprayed on the car went into the air. And the more paint on there, customers thought, the better."

Phillips says the gradual increase in the auto paint market's value reflects the premium that carmakers are willing to pay for higher solids paints and other new technologies. He cites an ultraviolet-curable clear coat for headlight lenses that garners a 60% gross profit margin versus a conventional polyurethane coating for the same application that would earn a margin of about 40%.

Automakers aren't giving away the store, however. They need better performing paints, but they are also under intense pressure to keep down the cost of building cars. "A lot of effort is being directed at reducing that total cost chain," says Richard Zahren, vice president of automotive coatings at PPG Industries.

M. Reggie Horne, vice president of Rohm and Haas's automotive coatings business, agrees. "In the past 24 months, cost has been a leading driver of where the technology goes next," he says.

One cost reduction strategy has been for the paint supplier to run the paint shop at the assembly plant on behalf of the car company. "We used to be paid the minute the paint hit the assembly line docks," BASF's Weber says. "Now we get paid after the car is painted."

The system has been around for about eight years. Because car companies aren't comfortable with having only one supplier for an important component, contracts often expire after only two or three years, according to PPG's Zahren. Some companies ensure competition by enlisting different paint suppliers at different plants.

Not surprisingly, paint companies think they can do a better job of painting than the automakers can. "The system gives us more levers to try to pull to get what the customer requires without the cost coming directly out of our pocket," Zahren says.

But paint companies haven't been invited into most assembly plants, especially ones in Asia, Zahren admits. "The vast majority are in the old mode," he says. "Some customers don't buy the concept. They believe they are effective at their operations, they understand the products, and it is in their best interest to manage them directly themselves."

"In the automotive area, aesthetics are key. You have to have a 10-year life, and the finish has to look exquisite."

ACKNOWLEDGING that car companies aren't always ready for radical--and sometimes expensive--change, paint makers are focusing on new products and technology that can be applied with existing equipment. DuPont, for example, rolled out a solvent-based technology earlier this year that it says can reduce emissions from the automotive clear coat while improving performance of this protective outer layer.

DuPont says automakers that adopt the technology, called Super Solids, get low-solvent emissions without the high cost of converting to a solvent-free approach such as powder coatings. The technology was introduced in May on a Dodge Durango assembly line in Newark, Del., where it reduced emissions in the clear coat by 25%.

The coating used in Newark is 65% solids, versus the conventional 50% for a clear coat, and is being applied without equipment modifications. The trick to the loading of more solids is DuPont's functional oligomer chemistry. According to Robert R. Matheson Jr., manager of strategic technology for DuPont Performance Coatings, functional oligomers allow DuPont to reduce the molecular weight of the resins. Less solvent is needed because the low-molecular-weight resins are less viscous.

The chemistry, Matheson says, is simple. Lower molecular weights are normally considered undesirable because properties like scratch and mar resistance usually decrease proportionally with molecular weight. But if a careful synthesis technique like catalytic chain transfer with cobalt complexes is used to retain the number of functional groups in the oligomer as molecular weight decreases, molecular weight is no longer a problem. "The insight here is to realize that low molecular weight itself is not bad, but a nonfunctional molecular weight is catastrophically bad," he says.

Matheson says the technology has been used in the lab to create coatings that are 88% solids. But at such high-solids levels, some minor modification to equipment is needed.

Functional oligomers are also used in DuPont's SupraShield technology, which was introduced last year at Ford Motor Co.'s Wixom, Mich., plant. Functional oligomers are additionally being used at a General Motors unit in Brazil. In contrast to Super Solids' environmental benefit, it's the improved scratch and mar resistance associated with the functional oligomers that makes SupraShield desirable.

	OLIGOMERS A car painted with DuPont's SupraShield technology, which allows for better scratch and mar resistance in the clear coat. DUPONT PHOTO

THOUGH THE MARKET may be receptive to a drop-in technology like Super Solids, it has been less enthusiastic about technologies that may offer overall efficiency at a high up-front cost. A case in point is Power Prime, a PPG system where the first two layers of paint are applied in separate electrodeposition baths. This process saves the step of spray painting on the primer coat.

The single line that was using the technology--a Dodge Dakota plant in Campo Largo, Brazil--was shut down because of economic conditions there. But, Zahren says, Power Prime has run into two additional problems. One is that the technology can be installed only on a new paint line. The other is that the car industry is moving toward colored primers, and the color can't be readily changed with Power Prime. "With the Power Prime setup, you can have any color you want--as long as it's the color in the tank," Zahren jokes.

But PPG has regrouped and, still aiming at the primer step, has developed another new technology, DuraPrime, that will be introduced by the end of next year. DuraPrime creates a smooth surface, like the primer, directly into the electrocoat layer. No primer application and resulting second oven cure is needed. "If I can put my base coat on without having to go through an oven, I decrease my capital cost and operating cost, and I don't have people working in that booth," Zahren says.

BASF had also been aiming at the primer with what it calls its Integrated Process. Weber describes it as a "wet-on-wet-on-wet" system. After the electrocoat, two waterborne-colored base coats and then a powder-slurry clear coat--a powder dispersed in water--are applied. The technique has been used to paint the Mercedes-Benz A-Class in Rastatt, Germany, for the past four years.

But the powder slurry is open to criticism. Some experts say acceptance has been slow. Zahren of PPG, which along with DuPont is supplying dry-powder clear coats for the BMW 5 and 7 series in Dingolfing, Germany, claims that slurries can be troublesome and says dry-powder clear coats will ultimately prevail. He points out that dry powders have been widely accepted in the primer layer, with more than a dozen lines in North America using the technology.

But Weber says BASF has had great success with powder slurry, which has been used on 1 million Mercedes since it was introduced. He says there is additional interest from automakers that are building new assembly plants.

And, Zahren concedes, using the slurry technology avoids the equipment overhaul that's needed to adopt dry powders. This is a plus that PPG is investigating. "We have a development under way to get all the advantages of powder slurry without some of the drawbacks of trying to deal with powder mixed with water," he says.

Another BASF technology aimed at efficiency is DynaSeal. Introduced late last year, DynaSeal coatings are used on sheet-molded compound (SMC) parts--the fiber-glass-reinforced thermoset panels used on bumpers and hoods. SMC parts are difficult to paint because of outgassing, a phenomenon in which the part gives off solvents while the paint is curing.

BASF technology seals the porous SMC part through a UV curing of the paint, followed by a thermal cure for durability. The technology reduces repairs, boosts efficiency, and requires less paint, the firm claims.

ALTHOUGH THE PAINTS used to coat plastic parts are similar to those applied to the rest of the car, they come with their own challenges because paint doesn't readily adhere to plastic, Rohm and Haas's Horne notes. "That is where we have had long-standing competitive advantage in the industry," he claims. Another wrinkle is that substrates are continually changing and becoming lighter because of increasing pressure on automakers to make cars lighter for fuel economy.

Rohm and Haas is building a technology center in Lansing, Ill., intended to support customers that make painted plastic parts for the auto industry. One potential new technology for plastics is powder coatings, which traditionally are applied only to metal because of the heat involved. Rohm and Haas already has had success with powders for wood applications, Horne says, and "we're interested in evaluating powder for areas other than metal."

Like architectural paint makers did 30 years ago, automotive paint companies want to take the trace amount of lead out of the primer layer. Although new paint lines are lead-free, Zahren notes that about 50% of the world's auto paint lines still use lead.

Paint makers are even employing nanoparticles. PPG is incorporating nanomaterials in clear coats being commercialized for the Mercedes-Benz. "We use nanoparticles in such a way that drastically cuts down the amount of dullness and cloudiness that develops when you get scratches from washing the car and other environmental factors," Zahren says.

PPG and equipment maker Behr Systems are developing a technology for the base coat that Zahren likens to an ink-jet printer. Called Dynamic FlexColors, the technology allows for color change on demand at the painting booth. "This is a process that takes a limited number of color bases and mixes them at the head to produce whatever color you want to dial in," he says.

Although FlexColors would require new painting equipment, the upside is that automakers could use it to charge premium prices for a semi-customized product. A novel painting technology like FlexColors isn't for every car company, but for those hesitant to invest in the new or the bold, the paint industry is ready with products that work with what they have.

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Copyright © 2002 American Chemical Society