Anyone pulling a really old bottle of Windex or Formula 409 spray cleaner from the back of the pantry is in for a pleasant surprise. The stuff still works great—perhaps better than a recently purchased bottle—cleaning windows and walls easily and drying quickly with no streaking or smearing.
Until about a decade ago, Windex, Formula 409, and many other hard-surface cleaners owed much of their cleaning power to ethylene glycol monobutyl ether, or EGBE, a glycol ether solvent renowned for its ability to cost-effectively remove both water-soluble soils and water-insoluble oils and greases.
“It is a tremendous solvent. It’s magic,” says Martin Vince, a chemist who runs LizMar, an Ontario-based formulation consultancy.
EGBE came under fire for health reasons, including its ability to cause red blood cell breakage when inhaled, and consumer goods makers largely removed it. But the ingredients substituted for EGBE were often volatile organic compounds (VOCs) or presented other environmental problems. Sometimes they just didn’t clean very well. And EGBE continues to be used in many industrial and institutional cleaning products.
Now, a new round of solvent replacement is taking place in laundry detergents, spray cleaners, and other cleaning products for home and industry. Multiple solvents are being added or removed for performance, environmental, and human health reasons.
For chemical makers, the upheaval means a business boom. Over the past year, companies, often the very ones that make glycol ethers and other traditional solvents, have come out with a flurry of new products.
They run the gamut from biobased to synthetic, from solvent to surfactant, but they are all intended to help customers in the cleaners business create formulas that are robust, cost-effective, and green. As a result, these are busy times for formulation chemists at cleaning product companies across the U.S.
Last October, two icons of corporate America—Procter & Gamble and DuPont—announced plans to use cellulosic ethanol as a solvent in Tide Coldwater Clean, a member of P&G’s flagship laundry detergent family. The cold-water version of Tide is marketed to consumers seeking to reduce energy consumption.
At present, ethanol derived from corn kernels helps keep Tide Coldwater’s myriad ingredients together in solution. DuPont is building a plant in Iowa that will make ethanol from corncobs and stalks instead. Blending this cellulosic ethanol into Tide Coldwater will repurpose more than 7,000 tons of agricultural waste a year, the partners say, and in the process save the energy needed to do all the clothes washing in homes across California for a month.
For DuPont, the agreement with P&G is part of a growing focus on the home and fabric care market, according to Simon Herriott, DuPont’s global business director for biomaterials. For about five years the company also has been marketing 1,3-propanediol, another biobased chemical in its portfolio, to the household products industry.
Propanediol’s main use is as a raw material for DuPont’s Sorona brand fiber. One of its next-largest markets, Herriott says, is household care, where it has a lot of room to grow as a solvent, stabilizer, and enzyme carrier. Propanediol is found, for example, in a spray cleaner and a concentrated laundry detergent marketed by Method, a purveyor of environmentally friendly cleaning products.
Herriott is happy with this business, but he sees the potential for DuPont’s solvents to go beyond the niche market served by Method. “Mainstream consumers are increasingly concerned about the impact their own personal actions have on the environment,” he says, and this trend is influencing home care product firms. “We’re at an inflection point between the green pioneers and major mainstream formulators.”
Another new solvent taken up by both Method and Seventh Generation, a competitor in the green consumer goods space, is ethyl levulinate glycerol ketal, manufactured by the biobased chemicals start-up Segetis. The ketal is found in the Method laundry detergent and in specialty spray cleaners from both Method and Seventh Generation.
For Clement Choy, senior director of advanced innovation at Seventh Generation, the ketal is a welcome addition to a woefully small arsenal of solvents his environmentally rigorous company can use. Choy, a chemist, is familiar with the wider world of solvents. Before joining Seventh Generation in 2008 he spent more than a quarter-century at Clorox and P&G, which had more liberal criteria for choosing solvents.
“We are definitely more selective and more restrictive,” Choy says about his current employer. For Seventh Generation, glycol ethers are verboten, and synthetics are avoided whenever possible. The company also won’t use VOCs, a restriction that eliminates “a fair number of products out there,” Choy says.
Seventh Generation began working with Segetis in 2011. The following year it formulated ethyl levulinate glycerol ketal into a new line of spray cleaners for stone, wood, and stainless steel. Its main role in these products isn’t so much to dissolve soil or grease but to help solubilize fragrance oils and keep the overall cleaning formula stable.
Method hooked up with Segetis even earlier, coming out with the laundry detergent and a ketal-containing tub and tile cleaner in March 2011. In addition to ethyl levulinate glycerol ketal, the bathroom cleaner includes ethyl levulinate propylene glycol ketal. The two solvents work together to dissolve stains and soap scum, according to Kaj Johnson, a product development director at Method who goes by the title green chef.
And for the laundry detergent, which is superconcentrated, Method relies on a system of four solvents: propanediol, ethyl levulinate glycerol ketal, glycerin, and methyl esters. In addition to providing cleaning power, the system makes the formula compatible, flowable, and phase stable under extreme storage conditions.
Like Choy, Johnson is happy to have a growing family of sustainable solvents at his disposal when formulating products. But that’s not enough, he cautions.
“If sustainability were all we were concerned about, we would have a very simple task,” Johnson says. In addition, human safety, effective cleaning, compatibility, stability, degradability, and surface safety all need to be considered. To best achieve these goals, he still seeks non-VOC solvents with broad surface safety, a broader portfolio of solubility parameters, and broad pH and heat stability.
Johnson works with non-VOC, biobased ingredients because Method’s upscale, environmentally conscious customers demand it. For Joe Zhou, vice president of R&D at Misco Products, a Pennsylvania-based maker of cleaners for the commercial and industrial markets, the demands aren’t so lofty. His customers are janitorial firms seeking products that clean quickly, effectively, and economically.
That means Misco continues to use EGBE in many of its traditional products, such as its MPC brand concentrated glass cleaner for the maintenance market. “EGBE is a very, very good solvent and very cost-effective,” Zhou says. “It’s like a Chevrolet—a dependable workhorse.”
But for its Elements glass cleaner, part of a line it calls “environmentally responsible maintenance solutions,” Misco has replaced EGBE with a blend of diethylene glycol monobutyl ether and propylene glycol mono n-butyl ether. Unlike EGBE, these glycol ethers aren’t readily absorbed by the skin and aren’t associated with blood cell breakage, the firm says.
Misco is using propylene-based glycol ethers—so-called P-series glycol ethers—to replace EGBE in most of the new products it develops, according to Zhou. The catch, he says, is that there’s no one drop-in replacement for EGBE. The company often must tailor blends out of propylene glycol monopropyl ether, dipropylene glycol monopropyl ether, propylene glycol mono n-butyl ether, and dipropylene glycol mono n-butyl ether.
Vince, the formulation chemist, also must get creative for customers that come to him seeking to replace EGBE. Sometimes those firms are developing green formulas to appeal to municipal buyers with a mandate to purchase cleaners bearing an eco-label.
Other times, customers need to remove VOCs to make their product comply with Environmental Protection Agency laws or with state regulations that started in California but are now spreading across the country. Canada, where Vince’s firm is based, will soon enact similar rules.
“In the past, companies would label their products ‘Not for sale in California,’ ” Vince says. “Now, as more and more states adopt the California standard, having two distribution channels doesn’t wash anymore.”
And soon to affect cleaning product manufacturers is the United Nations Globally Harmonized System of Classification & Labelling of Chemicals, or GHS, which will make chemical hazard information more transparent on product labels and safety data sheets. The Occupational Safety & Health Administration wants U.S. manufacturers to be in compliance by June 1.
Vince notes that GHS requires the use of pictograms to convey hazards. The health hazard symbol, which depicts a human figure with a starlike light on its chest, is particularly forbidding. “It’s something you don’t want on your product,” he says.
For Bob Stahurski, chief executive of the industrial cleaners firm Nyco Products, it was mostly the threat of new VOC regulations that prompted the creation of a line of ready-to-use spray cleaners based on butyl 3-hydroxybutyrate, a cleaning solvent developed by Eastman Chemical.
Before the solvent, named Omnia, was launched last year, coming up with EGBE replacements wasn’t easy, according to Stahurski. “We were looking for the trifecta of a safe solvent, a product with exceptional performance, and a low-vapor-pressure VOC,” he recounts. “Traditionally we could only get two out of three.”
The company formulated some cleaning products with other glycol ethers but found they were expensive and not always compatible with the rest of the formula. It also encountered flammability problems. So when a representative from Eastman’s solvents sales team approached Stahurski about being a sounding board and development partner for the firm’s new solvent, he was all ears.
Eastman, a major manufacturer of glycol ethers, had embarked on the search for an effective but environmentally friendly solvent several years ago, according to Carol Perkins, head of Eastman’s industrial and household care business.
The company tackled the problem methodically, starting with a database of some 3,000 molecules with potential as cleaning solvents and whittling it down to one through a combination of in silico and wet-lab testing.
Since launching Omnia, Eastman has been “overwhelmed by sample requests,” Perkins says, both from companies moving away from solvents such as EGBE and from firms that have already reformulated but aren’t happy with the results. “They come saying, ‘Please help us get that performance back,’ ” she says.
Also claiming robust customer interest in new solvents is Elevance Renewable Sciences, which converts vegetable oils into specialty chemicals with olefin metathesis technology invented by Nobel Laureate Robert H. Grubbs.
The Illinois-based company was formed in 2008. Two years later it started pursuing surfactants based on Elevance feedstocks in cooperation with the surfactants manufacturer Stepan.
The result, according to Andy Corr, head of consumer and industrial ingredients for Elevance, is a surfactant called Steposol MET-10U, which Stepan launched early last year as a replacement for solvents such as n-methylpyrrolidone and methylene chloride in adhesive removers and paint strippers. The surfactant also can be used in household and industrial cleaners in place of glycol ethers.
Soon after Stepan debuted its surfactant, Elevance came out with its own product, Elevance Clean 1200, a heavy-duty degreasing solvent aimed at manufacturing, food processing, and transportation maintenance customers looking for ingredients that are considered low vapor pressure by California and have a low enough vapor pressure or enough carbon atoms to be exempt from EPA’s VOC designation.
Clean 1200 is being marketed as a replacement for aromatic hydrocarbons and d-limonene, a citrus-derived VOC. In addition, the new product can provide a performance boost to dibasic esters and soy methyl esters, solvents that are VOC compliant but can have performance shortcomings, Corr says.
Elevance and Stepan already have some early customers and others with high interest in the new products, according to Corr. Customers are divided roughly equally between ones that are confronting solvent replacement for the first time and ones that switched but aren’t satisfied. Some in the latter category “have had to give up a hell of a lot of performance,” he says.
That’s not the view of Zhou, the R&D head at Misco, who has done his share of solvent replacement for the firm’s Elements line of cleaners. In some products, Zhou says, Misco replaced EGBE with P-series glycol ethers from Dow Chemical. In others it replaced petroleum solvents and d-limonene with soy methyl esters and ethyl lactate, two biobased solvents. Zhou says both Elevance and Eastman have asked him to try their new products but that at present he is happy with the solvent choices he has.
Those are comforting words to executives at Dow, a leader in glycol ethers and related cleaning product ingredients, including polyethylene glycols and propylene glycol.
The firm considers EGBE to be safe when used appropriately. Steve Vogler, global marketing director for Dow’s home, institutional, and personal care solutions business, argues that EGBE has been tarred by association with glycol ethers such as ethylene glycol methyl ether, which has been shown in lab animals to have adverse reproductive effects.
Dow sells EGBE to companies that want it, even as it acknowledges that other products have more favorable toxicity profiles. “We have a pretty good track record of defending E-series glycols,” Vogler says, “but overall people are looking for things on the propylene glycol side, so when concerns come up we just automatically run to the P-series.”
That line includes about 10 products, several of which are low-vapor-pressure VOCs and thus EPA exempt. Dow’s newest P-series product, launched last year, is dipropylene glycol phenyl ether. According to Vogler, it manages to be a low VOC while providing minimal streaking. Another new solvent from Dow is Diamosolv 323, a plant-derived ester aimed at degreasing applications.
Vince, the consultant, says it’s going to take all the new products from Dow and its competitors to replace EGBE and other unwanted solvents in industrial and institutional cleaners. He doesn’t see any single winner but rather modest market inroads by all of them as cleaning product companies reformulate.
The reformulation is a boon both for experts such as Vince and for people who work in industrial environments. “It means business for me, but more importantly it means a healthier and safer workplace,” Vince says. “The products these guys are going to be using day in and day out will be safer, and people will live longer.”