(Reuters) - 3M Co , the maker of Scotch tape and Post-it notes, reported a 2% fall in quarterly revenue and lowered its full-year earnings outlook, hurt by slowing demand for its products in key markets such as China.Net income attributable to the company rose to $1.58 billion, or $2.75 per share, in the third quarter ended Sept. 30, from $1.54 billion, or $2.64 per share, a year ago, helped by a gain from a divestiture.Net sales fell to $7.99 billion from $8.15 billion.