The Dutch chemical company Akzo N.V. and E. I. du Pont de Nemours & Company announced a surprise deal today ending what Akzo called ''the biggest industrial patents battle of this century.''
''This is a historic event,'' an Akzo spokesman, Marco Overdiep, said of the agreement, which ends 11 years of litigation in courts around the world over production techniques for the superstrong aramid fiber.
Under the deal, details of which were not disclosed, Akzo and Du Pont will suspend all legal battles and grant each other industrial patents for the manufacture of the fiber, which is sold by Du Pont under the Kevlar name and has been baptized Twaron by Akzo.
Analysts said that by removing uncertainty among customers, the deal would probably pave the way for a boom in the superfiber market, which is now worth $150 to $225 million a year but which could triple by the year 2000.
The fiber is already used in the automotive, aerospace and defense industries. Its extreme strength and relatively low weight qualify it for use in such products as bulletproof vests and car tires, but it is also used as reinforcement in airplane parts and as a replacement for asbestos.
Akzo and Du Pont, the world's only aramid producers, will now be able to compete freely in nearly all markets.
One exception remains, however. The United States is the largest single market for aramid fibers, with about 9,000 tons sold in 1987, and it is still closed to Akzo after an import ban by the United States International Trade Commission.
Mr. Overdiep said Akzo had won an agreement with Du Pont to sell ''a limited but steadily growing amount of aramid fibers in the United States'' if the commission lifts the ban.
Analysts said recent court orders in Britain, West Germany and France, all in favor of Akzo, appear to have put new life into deadlocked talks between the chemical giants.
Akzo has a single aramid fiber plant in the Netherlands but is believed to use only half its total production capacity of 5,000 tons a year.
Du Pont has a total annual capacity of some 20,000 tons, but analysts said its actual output was probably closer to 9,000 or 10,000 tons.