Terms of the deal were not disclosed.
Wellman is Europe's largest recycler of PET (polyethylene terephthalate) bottles and a maker of polyester staple fiber and recycled PET products. It has three production facilities in Europe with output of over 153,000 tons a year.
Its Ireland plant is capable of converting waste polyester into 100% recyled fiber, which can be further processed to be used in several premium products, it said.
Indorama, valued at $5.3 billion, has said it planned to spend $3.8 billion to double its capacity to 10 million tons by 2014. It is southeast Asia's third-largest petrochemical firm by market value after Malaysia's Petronas Chemicals Group and Thailand's PTT Chemical Pcl.