Finnish chemicals group Kemira reported a weaker-than-expected fourth quarter profit after a fall in the titanium dioxide market hurt its German joint venture Sachtleben.

Wednesday's results underscored the weak position of Sachtleben as its joint owners, Kemira and Rockwood, look for a buyer. Sources said last week that the companies were renewing efforts for a sale.

"The market environment for titanium dioxide changed completely in 2012, causing a deterioration of the performance of the JV Sachtleben with a substantial negative impact on our EPS," Chief Executive Wolfgang Buechele said.

Kemira shares dropped more than 4% after the company's fourth-quarter core operating profit fell unexpectedly by around 2% from a year earlier to €33.7 million ($45.59 million). Analysts in a Reuters poll had expected a 20% rise on average.

The titanium dioxide industry, led by companies such as Dupont and Saudi Arabia's Cristal Global, has had a roller-coaster ride in the past few years.

Titanium dioxide particles can be used to reflect light, creating whiteness in paints and car coatings. They can also be used in sunblock and on plastic or wood for protection.

Producers cut capacity in 2009 only to see demand rebound in the following two years, driven by the automotive sector. But prices came under pressure again last year as idled plants came back on stream.

Kemira launched a new restructuring program last year to cope with the tougher business environment. The company said it expected adjusted core operating profit to be "significantly higher" in 2013.