Platform Specialty Products Corp., the specialty chemicals company founded by Martin E. Franklin, agreed to acquire agricultural chemicals maker Arysta LifeScience Ltd. for about $3.51 billion.

Arysta is being sold by funds controlled by private-equity firm Permira Holdings Ltd., Miami, Florida-based Platform said. The deal is expected to close in the first quarter of 2015 and be funded with cash on hand, convertible equity and debt.

Arysta, which had net sales of $1.5 billion in 2013, supplies insecticides, fungicides and herbicides, according to the statement.

Franklin, Platform’s chairman, has said he plans to acquire a “portfolio” of specialty-chemical companies. Today’s deal is the fourth acquisition announced by Platform in just over a year, according to data compiled by Bloomberg.

The company bought Chemtura in April for $1 billion, Agriphar SA for an undisclosed price in August and MacDermid Group Inc. for $1.8 billion in October 2013

Additional reporting by Anthony Noto.