* Recent factory data from U.S., China, Europe caps gains * Shanghai copper open interest up as fresh longs enter market * Coming Up: U.S. CFTC commitment of traders data ; 1930 GMT (Updates prices; adds quotes, details) By Carrie Ho SHANGHAI, Sept 21 (Reuters) - Copper rebounded back towards 4.5 month highs on Friday, as optimism that recent easing steps set by the United States, Europe and Japan would offer a new life line to global growth outweighed a raft of poor factory data in the prior session. London copper has risen 14 percent since early August, helped by stimulus moves such as bond buying by the European Central Bank, a third round of quantitative easing, or QE3, in the U.S. and a doubling of asset purchases by the Bank of Japan. But gains are expected to be capped by recent soft factory data from the U.S., Europe and China, which suggested governments still have much to do to lift the global economy out of its current rut. Three-month copper on the London Metal Exchange had risen 0.75 percent to $8,326.75 per tonne by 0702 GMT, back towards a 4.5 month top of $8,422 hit on Wendesday, which was the highest since May 2. The most active January copper contract on the Shanghai Futures Exchange closed up 0.73 percent at 59,740 yuan ($9,500) per tonne, though it is heading for a weekly fall of around 0.5 percent. ShFE copper's net daily open interest was up 8,494 lots by the midday close, which, together with rising prices, showed that fresh longs had entered the market. "Sentiment is largely positive as governments seem inclined to stimulate their economies. Investors are counting on the Chinese government staying on a stimulus path at least until the 18th Communist Party Congress," said a Shanghai-based trader. The Communist Party Congress, China's most important political event, is held once every five years with top leaders being replaced only every decade. It is expected to be held in October but the exact timing has not been announced. "Copper prices continue to consolidate within the uptrend that was triggered by recent stimulus policies by major economies. Investors are waiting for the next trading cue but in the meantime, no one dares to go short for too long," said a Shanghai-based trader with an international firm. But a slew of soft data on Thursday cast a pall over the demand outlook for metals. The U.S. manufacturing sector closed out its worst three months in September since the third quarter of 2009, according to financial information firm Markit. Export orders fell for a fourth month running as demand from Europe and Asia faded, with September's slide the steepest in nearly a year. China's flash purchasing managers index on Thursday showed the country's manufacturing sector contracted for an 11th month in a row in September. Base metals prices at 0702 GMT Metal Last Change Pct Move YTD pct chg LME Cu 8326.75 61.75 +0.75 9.56 SHFE CU FUT JAN3 59740 430 +0.73 7.91 HG COPPER DEC2 379.85 3.95 +1.05 10.55 LME Alum 2117.50 7.50 +0.36 4.83 SHFE AL FUT DEC2 15740 40 +0.25 -0.66 LME Zinc 2128.50 18.50 +0.88 15.37 SHFE ZN FUT JAN3 15730 130 +0.83 6.32 LME Nickel 18090.00 195.00 +1.09 -3.31 LME Lead 2288.00 23.00 +1.02 12.43 SHFE PB FUT 16155.00 155.00 +0.97 5.69 LME Tin 20950.00 400.00 +1.95 9.11 LME/Shanghai arb^ 1717 Shanghai and COMEX contracts show most active months ($1 = 6.3038 Chinese yuan)

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