ATLANTIC RICHFIELD <ARC> UNIT BUYS TECHNOLOGY Atlantic Richfield Co said it has acquired exclusive worldwide rights to the methyl methacrylate technology of Texas Eastern Corp's Halcon SD Group affiliate for undisclosed terms. The company said the technology will allow it to introduce a cleaner and more efficient way of making methyl methacrylate, a liquid monomer used to make resins for acrylic sheet, coatings, molded parts and products and plastic impact modifiers. ARCO said it is reviewing options for commercialization of the technology.