U.S.-based Huntsman Corp and Switzerland's Clariant AG are combining to create a chemical manufacturer with a market value of more than $14 billion, they said on Monday, after years of tentative mutual approaches.

The deal creates a global specialty chemicals company that is 52 percent own by Clariant shareholders and valued at around $20 billion when including debt, Clariant said in a statement.

Reuters reported in March that Clariant and Huntsman previously ended merger talks late last year over a disagreement about who would play the lead role.

Many European companies have embarked on deal making as growth in the chemicals industry has slowed. European businesses have particularly suffered, losing market share to rivals in Asia, where demand is growing faster, or to North America, where energy is cheaper.

Clariant Chief Executive Hariolf Kottmann and Huntsman CEO Peter Huntsman said they had developed a professional and personal friendship eight years ago, preceding intensified talks over the past five weeks that resulted in a combination of the two companies.

" Hariolf and I had discussions as friends and as business colleagues. But this is the first time in all those years that we actually engaged our teams to actually get a deal done," Huntsman told journalists on a conference call.

The deal combines Clariant, a Pratteln, Switzerland-based maker of aircraft de-icing fluids, pesticide ingredients and plastic colouring , with Woodlands, Texas-based Huntsman, whose chemicals are used in paint, clothing and construction.

Peter Huntsman will become CEO of the combined company, called HuntsmanClariant, while Kottmann will become chairman. The combined company will be headquartered in Switzerland, although its operational centre will be in Woodlands, Texas.

Kottmann has spent several years restructuring Clariant. He divested underperforming businesses including textile and paper chemicals in 2012 and placed more responsibility with lower level managers for faster decision-making.

In mid-2015 he started carving out Clariant's plastics and coatings business into a separately managed entity.

Plastics and coatings will be an integral part of the new company, Kottmann said, though he reiterated that it could be sold to fund any further takeovers.

Investor pressure had been growing on management to identify a growth strategy for Clariant, which was formed in the mid 1990s from parts of Switzerland's Sandoz and Germany's Hoechst.

A source familiar with the transaction said the combined group would use its bigger fire power to pursue further deals.

Kottmann said in the call that all of the businesses of the new enlarged entity would merit "strategic thinking".

Citi and UBS advised Clariant on the transaction, while Bank of America Merrill Lynch and Moelis acted as Huntsman's financial advisors. European peers BASF, Solvay,

European peers BASF, Solvay, Evonik and Lanxess have agreed multi-billion takeovers since mid-2015. A $130 billion merger and three-way split between U.S. groups Dow and DuPont is underway, while industrial gases groups Linde and Praxair are seeking to combine.