HONG KONG, Oct 16 (Reuters) - China's biggest umbrella exporter has filed for an initial public offering in Hong Kong as the city enters a third week of pro-democracy protest dubbed the "umbrella revolution" after demonstrators used the devices as shields against pepper spray.

Jicheng Umbrella Holdings Ltd is raising funds to build a new factory and expand its output, according to its preliminary IPO prospectus filed late on Wednesday. The company, based in Jinjiang in the southern Fujian Province, didn't disclose the size of the planned deal.

Hong Kong didn't rank among export-dependent Jicheng's five biggest markets last year. But the city emerged as the company's third-largest market for the six months ended in June 2014, according to the IPO prospectus.

Jicheng, founded in 1996 and controlled by businessman Huang Wenji, is the third-biggest umbrella maker in China, but unlike its competitors focuses on sales to overseas markets. Nearly three-quarters of sales were to clients in Japan in 2013, with mainland China its second-biggest market by revenue with an 11.7 percent share.

It had 483.6 million yuan ($79 million) in sales in 2013, up 28 percent from a year earlier. Profits jumped 35 percent over the same period to about 60 million yuan.

Ping An of China Capital was hired as sole sponsor of the IPO. (1 US dollar = 6.1230 Chinese yuan)