ARLINGTON — The maker of the ubiquitous red Solo cups, Dart Container swooped in Wednesday to buy up the assets of a defunct cleantech startup in Arlington for $3.5 million.

MicroGreen Polymers’ assets were auctioned off by its main backer, the Confederated Tribes of Grande Ronde in Oregon. The tribes and other investors sunk roughly $80 million into MicroGreen.

Less than a year ago, the company was ramping up production of its heat-resistant, recyclable plastic cups, which were being used by three major airlines for coffee. MicroGreen’s leaders and supporters promoted their cups’ ability to push out Styrofoam, which can’t be recycled, from the marketplace. They claimed the Arlington company would revolutionize the food packaging industry.

But the company was selling a fancier and costlier version of a commodity product. Sales were hard to come by. The airline contracts were big, but not big enough to offset high production costs or cover the company’s high-interest loan payments.

MicroGreen abruptly closed last spring. It employed more than 160 people at its peak.

The Grand Ronde Tribes hired the Connecticut-based Branford Group to sell off the assets.

What becomes of the company’s promising technology is unclear.

Dart Container could not be reached for comment. The Mason, Michigan-based company could re-open MicroGreen’s Arlington plant or shut it down. It could use the intellectual property in its own production operations, or stick it on a shelf, where it won’t threaten Dart’s market share.

Dart Container has plants in Tacoma and Tumwater.

Aiooa, a company started by a core group of former MicroGreen employees, bid $425,000 for the intellectual property at Wednesday’s auction.

Even so, organizers stopped the auction by early afternoon because the auction’s revenues couldn’t beat Dart Container’s bulk bid.

The MicroGreen veterans at Aiooa have been doing freelance engineering work while they refine their business plan, Tony LaSalata said. He was head of engineering at MicroGreen and is one of Aiooa’s co-owners.

He declined to say what the new company would have done with the intellectual property.

Speaking to the Rotary Club of Arlington last May, Aiooa co-owner and MicroGreen co-founder Krishna Nadella said their new venture is focused on helping companies set up and run manufacturing systems, rather than producing consumer goods itself.

“We failed as a manufacturer of low-cost items, but now we’re designing all new products and equipment,” he said.

Material from the Arlington Times was used in this report.

Dan Catchpole: 425-339-3454; dcatchpole@heraldnet.com; Twitter: @dcatchpole.