Private equity companies Pamplona, HgCapital and Charterhouse are left in preparation for the submission of their second round bids to acquire German insulation firm Armacell, following the withdrawal of Goldman Sachs Private Equity and Equistone from the auction, according to banking sources familiar with the matter.

Armacell is being sold by owner Investcorp., a private equity firm based in Bahrain that purchased the company in 2007, data from Thomson Reuters LPC revealed.

According to the sources, bankers are considering debt packages amounting to around 350 million to 400 million euros to back a potential buyout of the German company.

Armacell is the largest maker of flexible insulation in the world, claiming 40% percent of the global market. It currently employs approximately 2,400 people and has 19 plants in 13 countries across the world.

The auction sale is expected to draw up to 500 million euros ($650.47 million).