DANBURY, Conn. (AP) _ The Union Carbide Corp. announced plans Monday to build a new plant in Louisiana to make polyethylene plastics.

Polyethylene is the world's most widely used plastic and goes into such products as toys, trash bags and packaging.

Union Carbide's new plant in Taft, La., will use new technology to make high-performance polyethylene plastics for several large-volume markets, the company said.

Company spokesman Jim Haman wouldn't comment on the cost to build the plant, which will be located within the company's existing Star Plant complex in Taft. But he said the new plant would create 30 new jobs.

The plant will bring total polyethylene production capacity at the site to nearly 1.7 billion pounds annually, the company said.

''Locating this unit at our Star site will let us take advantage of some very favorable economics, as well as investment tax incentives expected to be provided by the state of Louisiana,'' said Roger B. Staub, president of Union Carbide's Polyolefins Division.

The plant is scheduled to begin operating in 1995 and will produce 650 million pounds of polyethylene plastic annually, the company said.