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Cleaning Conundrum

Seeing a performance gap, Eastman scientists invent a new cleaning solvent

by Michael McCoy
June 9, 2014 | A version of this story appeared in Volume 92, Issue 23

If your all-purpose spray cleaner doesn’t seem to work quite as well as it once did, it may not be your imagination.

Bowing to pressure from regulators, the makers of household and industrial cleaning products have been eliminating solvents that work well but don’t meet government standards for toxicity or volatile organic compound (VOC) content.

Credit: Eastman
Using their homemade scrub machine, Eastman researchers put their new solvent through the paces.
A dirt coated panel after a test with Eastman’s scrub machine.
Credit: Eastman
Using their homemade scrub machine, Eastman researchers put their new solvent through the paces.

Some companies have removed ethylene glycol monobutyl ether, which is considered a hazardous substance in California. Products such as dipropylene glycol monomethyl ether are being replaced because the Environmental Protection Agency has deemed them to be VOCs. These may be sound moves for health and the environment. But according to Carol Perkins, head of Eastman Chemical’s industrial and household care business, “It has left a big void in terms of performance.”

Eastman, a major manufacturer of solvents, decided to do something about it. The result, being rolled out now, is butyl 3-hydroxybutyrate, a chemical that Eastman says is new to the cleaning industry and, in fact, new to commerce altogether.

There’s no doubt that cleaning product makers need new solvents, according to Martin Vince, a formulation chemist who runs an Ontario-based consulting firm called LizMar. Vince figures that 30% of his business today is with companies looking to replace solvents and other ingredients for environmental reasons.

The need is greatest in the industrial market, Vince says, because cleaning products must be able to remove caked-on dirt, grease, and grime without smearing.

Eastman began the search for an effective but environmentally friendly solvent several years ago. Perkins and colleagues interviewed formulators, end users, environmental groups, and consultants to understand the trends in the industry. They also attended conferences where they encountered skeptics who dismissed the idea of safer solvents with the phrase “green does not clean.”

Undeterred, they decided to approach the problem methodically. The first step, according to Jos de Wit, an analytical chemist at Eastman who worked on the project, was to assemble a database of some 3,000 molecules with potential as cleaning solvents.

Eastman scientists put the solvents through in silico screens that sifted for molecules with the right balance of hydrophilic and lipophilic properties. The researchers whittled the database down to 370 candidates and then began screening for safety. At 70 compounds, they embarked on in vitro and other toxicological testing and pared further.

The first molecule to emerge from the screen, an ester alcohol, was a bust, de Wit says. It was a decent cleaner, but after testing, the researchers realized it didn’t meet California’s VOC standards.

Around the same time, the screening process also yielded butyl 3-hydroxybuty­rate. Another ester alcohol, it passed the VOC test. But did it clean?

When the Eastman team embarked on the search for a new solvent, it learned the industry had no standard way to assess cleaning ability. “We use the spray-and-pray method,” they heard from one potential customer. So de Wit decided to turn a device used to test coatings into a scrub machine that would test a solvent’s cleaning ability in a reproducible manner.

Armed with his new machine, de Wit put butyl 3-hydroxybutyrate through the paces, and it shined. For example, in a tar removal test, a neutral-pH cleaner containing 2% of the new solvent was superior to cleaners with low-VOC solvents such as dipropylene glycol n-propyl ether. It even beat cleaners with VOCs like ethylene glycol monobutyl ether, according to Eastman.

The testing proved that the solvent works, but the Eastman developers also wanted customers to know that it’s safe, so they devoted two years to getting it on the Safer Chemical Ingredients List maintained by EPA’s Design for the Environment (DfE) program. It also won a place on the CleanGredients list maintained by the nonprofit GreenBlue.

Meanwhile, the company scaled up butyl 3-hydroxybutyrate output, turning its Kingsport, Tenn., headquarters complex into what de Wit says is the world’s only large-scale producer. And it branded the solvent with the trade name Omnia.

Omnia is now fully commercial, Perkins says. To date, Eastman has one customer, in Europe, and several other firms are evaluating the solvent, she notes. Eastman is initially targeting the industrial and institutional cleaning market because of its need for new solvents and because customers value third-party certifications such as DfE.

Vince, the consultant, notes that other firms are also coming up with new cleaning chemicals. For example, a partnership between Stepan and Elevance Renewable Sciences recently launched a naturally derived surfactant, N,N-dimethyl 9-decenamide, as a solvent replacement. And Dow Chemical is promoting dipropylene glycol phenyl ether and other VOC-compliant solvents.

Perkins prefers not to put her team’s effort in terms of Eastman’s competition or the solvents the firm wants to replace. Rather, Eastman has a loftier ambition for Omnia: “We want to change the chemistry of cleaning,” she says.



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