The Cork-based owners of the Quality Plastics business are believed to have realised some €40 million from the sale of the company to Pipelife, an Austrian-Belgian joint venture.
The beneficiaries of the transaction include managing director Gary A Horgan and his sister Karen, who is commercial director, and other members of their immediate family.
The current management team will stay on with the organisation, which employs 174 people at two plants in Cork.
Talks were ongoing for about a month before a deal was struck early on Friday morning, at the very end of Quality Plastics' financial year.
This followed an initial engagement between both sides last year.
"It will be run exactly as it was being run before but as part of an international group," Ms Horgan said.
Her father Garry D Horgan established the business in 1970 and bought out his original business partner in 1990.
Based at White's Cross in Cork, Quality Plastics also has a presence in the British market.
With sales of €42 million in the financial year just closed, the company makes speciality plastic pipes and fittings for the construction, agriculture and plumbing and heating sectors.
Niall Welch of Cork firm Welch & Associates advised Quality Plastics, which had sales of €36.2 million in the year to March 2006 and pre-tax profits of €3.4 million.
While shareholders' funds stood at €17.4 million a year ago, the value of the deal was not publicly disclosed.
Quality Plastics specialises in "hot-and-cold" water systems for plumbing and heating, which is said to be the fastest-growing segment of the pipes and fittings market in Europe.
Its products are derived from speciality polymers and complex compounds, making them suitable for the replacement of metal in many applications.
Pipelife is a 50:50 joint venture between Austrian group Wienerberger AG and Belgian group Solvay SA.
"Pipelife intends to capitalise on this acquisition and on its own extensive network to serve clients with these products and technologies throughout Europe," the company said.
"Quality Plastics is a perfect complement for the Pipelife Group. It will reinforce one of Pipelife's fastest growing product lines - which is Hot & Cold - in addition to giving the group access to the Irish and UK markets," said the Pipelife chief executive Miguel Kohlmann.
