(Reuters) - Dow Chemical Co (>> The Dow Chemical Company) said it now expects to raise between $3 billion and $4 billion from asset sales in the next 18 to 24 months, at least double its earlier target, as it looks to shed businesses exposed to commodity price swings.

The bulk of what Dow Chemical plans to sell is housed in its performance materials business, which was mainly responsible for the company's weaker-than-expected quarterly results.

Dow Chemical shares were down 1.5 percent at $40.45 in early afternoon trading on Thursday.

The performance materials unit includes the epoxy and commodity chlorine derivatives businesses that Dow Chemical wants to sell.

"In performance materials, we are still facing significant headwinds and so that's why you see us increasing that divestiture target to $3 billion-$4 billion," spokeswoman Rebecca Bentley said.

Dow Chemical was earlier targeting proceeds of $1.5 billion from sales of non-core assets.

"It's possible that they will even increase that target again," UBS Investment Research analyst John Roberts said.

The company will shed its epoxy business through a joint venture or a sale, with a transaction expected in the near term, Chief Executive Andrew Liveris said on a conference call.

Demand for epoxy resins, used in windmill blades and a host of other products, has tumbled due to excess capacity in China and the loss of subsidies for wind energy in Europe.

Liveris said the company would sell parts of its chlorine and derivatives assets such as chlorinated organics -- used in electronics and refrigerants among other things -- and vinyls, used to make a raw material for water pipes.

The company said in August that it was also looking at options for its European construction materials businesses.

"We are moving away from being all things to all markets and going deeper and narrower into profit pools ...," Liveris said, adding the company's focus would now be electronics, packaging and agriculture.

The company sold its polypropylene licensing and catalyst business to smaller rival W.R. Grace & Co (>> W.R. Grace & Co.) for $500 million this month.

The largest U.S. chemical maker by sales has divested non-core businesses representing about $8 billion in revenue since 2009.

PLASTIC GAINS OVERSHADOWED

The performance plastics business, Dow Chemical's largest unit, has enjoyed margin expansion, driven by abundance of cheap shale-derived natural gas, used to produce ethylene, a building block for plastics. EBITDA at the segment shot up 32 percent.

The company expects strong margins to continue in the business, Chief Financial Officer William Weideman said on the post-earnings call, adding that its agricultural sciences business would continue to grow as well.

EBITDA at the performance materials business fell 36 percent in the third quarter.

Dow Chemical's net income rose 20 percent to $594 million, or 49 cents per share, helped mainly by the plastics, packaging, coatings and electronics businesses.

The adjusted profit was 50 cents per share, missing the average analyst estimate of 54 cents per share.

Revenue rose 1 percent to $13.73 billion. Analysts on average had expected $13.99 billion.

(Reporting by Garima Goel and Swetha Gopinath in Bangalore; Editing by Kirti Pandey and Saumyadeb Chakrabarty)

By Swetha Gopinath and Garima Goel