SCOTTSBURG, Ind. (AP) — A southern Indiana man who says he invented a microwavable plastic food container is suing two of the nation's biggest food packagers, saying they stole his ideas and never paid him despite signing confidentiality agreements.

Gary Hopkins and his company, Steamway Corp., filed suit against Oakland, Calif.-based Clorox Co., the parent of GladWare food containers, and Rochester, N.Y.-based Birds Eye, one of the biggest sellers of frozen vegetables, in Scott Superior Court. He is seeking unspecified damages.

Both companies say the lawsuit is without merit and that they will defend themselves aggressively.

Hopkins says more than a decade ago he developed plastic containers with pinholes and steam vents, giving the effect of a miniature pressure cooker. That cut in half the time needed to heat frozen fish, chicken, vegetables or whole meals, while retaining moisture — improving the taste of microwaved food.

"Instead of bombarding frozen food with microwaves, we came up with a way to build steam pressure," Hopkins told The Indianapolis Star. "It's just a much better way to heat food."

Hopkins said he got seven patents and showed his invention to food packagers after they signed confidentiality agreements, hoping they would license his containers. His suit contends Birds Eye signed a confidentiality agreement in 2003, and Clorox did the same in 2004.

Hopkins said he provided the companies his research materials and sample microwavable trays and bags. He said they suggested some changes in design, which he spent thousands of dollars to make.

He said Clorox asked Hopkins for an exclusive right to purchase or license the technology but canceled its confidentiality agreement shortly after he sent the company a proposed licensing agreement. He noticed GladWare containers that were microwavable and had similar features to his prototypes appeared on store shelves soon afterward, the lawsuit contends.

In 2006, Birds Eye launched its new line of Birds Eye Steamfresh frozen vegetables, which the company's promotional materials said "steam perfectly right in the bag." Hopkins said he developed the technology.

A Birds Eye executive, Lois Warlick-Jarvie, said in an e-mail statement that Hopkins' lawsuit is "completely without merit, and we will aggressively defend the allegations against us."

Dan Staublin, a spokesman for Clorox, declined to discuss the GladWare technology but said the company also would "vigorously defend" itself.

Hopkins said he spent years and $3 million from friends and family on his product.

"Gary Hopkins came up with this a lot sooner than anyone else, because seven patents tells you something," said John Price, Hopkins' Indianapolis attorney.

But Hopkins may have a hard time proving his case. Hundreds of small inventors sue large companies each year, claiming that they swiped their ideas.

Hopkins will need to prove that the big companies didn't develop similar ideas on their own, said Lynn Tyler, a patent attorney at Barnes & Thornburg in Indianapolis.

"I've seen cases where big companies settle before it ever gets to trial, because they don't want the publicity or embarrassment," Tyler said. "And I've seen cases where little inventors have big egos, but their cases have no merit."

Hopkins, 54, says his company is now defunct and he is working for his brother's construction company. He hopes his lawsuit will recoup some of the millions he says he's lost.

"We blessed the world with a technology that saved time and made food taste better," he said. "But I think we've been ripped off everywhere we went."