Negotiators for Chrysler Corp. and the United Auto Workers headed toward a Tuesday midnight strike deadline, with union officials saying the talks were "dangerously slow" in the effort to avert a walkout by 70,000 workers in 15 states.

Job security and demands for increased wages and benefits from the resurgent Chrysler Corp. are the key issues for the UAW, while the company is pressing hard to combat foreign competition by cutting costs through more flexible work rules and job classifications, officials said.

"With less than 36 hours to go, virtually every major issue remains unsettled," a UAW spokesman said during afternoon negotiations here at company headquarters. "It's getting late."

The confrontation demonstrates that despite Chrysler's remarkable recovery since its $1.2 billion government bailout in 1980, the complex problems of Japanese import competition and automation still plague labor-management relations in Detroit.

The negotiations are further complicated because, for the first time, UAW's more militant Canadian wing has split off and is negotiating separately in Toronto for another 10,000 employes at six key facilities. A strike in Canada, which industry sources considered likely, would quickly force the shutdown of most of Chrysler's 50 U.S. facilities that depend on Canadian-made parts.

Industry analysts have estimated that a full-scale strike could cost the company $50 million a week.

UAW is also seeking to restore the 35-year tradition of "pattern" bargaining in which the Big 3 auto contracts expired simultaneously, giving the union greater clout in convincing a resistant firm to follow the pattern.

To restore the pattern, broken by the Chrysler crisis, UAW wants a two-year pact that would expire simultaneously with General Motors Corp. and Ford Motor Co. But the company is seeking the greater stability of a three-year pact.

The latest labor battle in the import-battered auto industry comes three years after Chrysler recovered from its brush with bankruptcy to score record profits of $2.4 billion in 1984, and $1.6 billion in the first half of 1985.

The UAW, whose members made $1.1 billion in concessions to keep the No. 3 automaker afloat, is now demanding "parity" with GM and Ford, where pay is slightly higher than the $13.23 per hour Chrysler average, and where pension benefits are about 10 percent higher.

Pensions are particularly costly for Chrysler because the company induced tens of thousands of workers to retire early during its 1979-82 slump, and now has the highest ratio in the industry of pensioners to workers.

Chrysler Chairman Lee Iacocca and UAW President Owen Bieber met Friday for the first time since talks began Aug. 12, but no progress was reported on the key issues.

The most troublesome issue, according to both sides, is "outsourcing," the auto industry term for the increasing use of outside sources -- foreign and nonunion -- to produce automobile components.

Chrysler manufactures only 30 percent of the parts for its vehicles, compared with roughly 50 percent and 70 percent for Ford and GM, respectively, according to industry data. In addition to importing foreign cars, Chrysler uses about 5 percent foreign components in domestic cars.

The union is seeking some form of limitation on subcontracting work to non-UAW sources, and guarantees against layoffs and plant-closings caused by outsourcing and automation.

Chrysler is arguing strongly against demands that it considers burdensome, Thomas W. Miner, Chrysler vice president and chief negotiator, said recently. "We are on a pretty good roll in the marketplace, and we certainly don't want a strike," Miner said, ". . . but on the other side of the coin, we are not willing to pay more than we should pay to avoid a strike."