Dover, Del. ? DuPont has agreed to sell its Invista textiles unit, which makes nylon and spandex, to two Wichita-based Koch Industries subsidiaries for $4.4 billion in cash, the companies announced Monday.

The deal with KED Fiber Ltd. and KED Fiber LLC is expected to close in the first half of next year and is subject to government approval, officials said.

DuPont chairman and chief executive Charles O. Holliday Jr. described the sale as a “bittersweet milestone” for the 201-year-old company, which created the synthetic fiber industry in 1938 with the introduction of nylon.

“The fibers businesses have been an important part of DuPont for many decades,” he said. “However, marketplace realities dictate they can best realize their potential as part of a company like Koch, which is fully committed to Invista and the markets it serves.”

Invista, formerly known as DuPont Textiles and Interiors, is the largest integrated fiber and intermediates business in the world, with 2002 revenues of $6.3 billion and 18,000 employees. Some of its better-known global brands and trademarks include Lycra, Cordura and Stainmaster.

DuPont’s sale of Invista is part of a companywide restructuring undertaken amid years of decline in the U.S. textile and apparel industries, mostly because of weakened demand and foreign competition. DuPont said last year it was cutting 2,000 jobs in its textiles unit.

“We have essentially looked at every piece of DuPont’s cost structure,” Holliday said, describing Wilmington, Del.-based DuPont as “a smaller but stronger company.”

Charles Koch, chairman and chief executive of Koch Industries, described the acquisition as “an excellent fit.”

“By combining Invista’s many capabilities and strong brands, primarily in nylon and spandex, with the polyester businesses of our KoSa subsidiaries, we will create a diverse company, well-positioned to compete in the global fibers and resins markets,” he said.

DuPont’s chief financial officer, Gary Pfeiffer, said the two companies would remain linked through service and ingredient supply contracts. He said the sale of Invista would substantially reduce the company’s exposure to fluctuations in raw material costs related to oil and natural gas.

Holliday said he could not yet say what DuPont planned to do with the proceeds from the sale. He mentioned debt reduction, prefunding of pensions and other obligations, and share buybacks as possibilities.