Two of the plants are extruding operations and one specializes in injection molding. They employ a total of 170.
The plants have been put up for sale as part of Atlantis' attempt to climb out of its financial problems. Atlantis shares are trading at 10 cents.
A day after the bankruptcy filing, Atlantis said it had agreed to sell its plastic films arm for $87 million to AEP Industries Inc., a publicly traded company based in South Hackensack, N.J.
Atlantis' molded plastics business has been sold for an undisclosed price to New York private equity fund Monomoy Capital Partners L.P.
Monomoy is consolidating auto-related manufacturers, and is expanding Casting Technologies Co., its aluminum parts operation in Franklin.