* To sell 81 million shares in IPO
* Shares to price between NOK 20 and NOK 25
* Pricing expected Oct 17, to start trading Oct 18 (Adds further details)
OSLO, Oct 1 (Reuters) - Norwegian conglomerate Orkla expects to raise up to $350 million from floating off its specialist chemicals arm Borregaard and also hopes to cut debt by $175 million, it said on Monday.
Orkla aims to sell 81 million shares or 81 percent of the firm to raise between 1.6 billion and 2 billion crowns ($280-349 million) and also expects Borregaard to repay 1 billion crowns of debt once it completes the listing.
The shares are expected to be offered for sale at a price between 20 and 25 crowns per share, which would value Borregaard at between 2 and 2.5 billion crowns.
"The final offer price per share may, however, be set above or below this indicative price range," Orkla said in a statement.
The institutional book-building will start Oct 3 and the offer is expected to price on Oct 17 before trading starts on the Oslo bourse on Oct 18.
In addition the bookrunners have been granted an over-allotment option equalling up to 15 percent of the final number of shares sold, Orkla added.
Borregaard operates a refinery that produces chemicals from biomass, such as timber, straw and other agricultural and forestry waste.
ABG Sundal Collier and UBS Investment Bank are the joint co-ordinators and joint bookrunners for the IPO, while DNB Markets, Handelsbanken Capital Markets and SEB Enskilda are acting as co-lead managers. ($1=5.7248 Norwegian krone) (Reporting by Balazs Koranyi; Editing by Greg Mahlich)