July 23 (Bloomberg) -- 3M Co., the maker of 55,000 products from Post-It notes to electronic road signs, said it will invest $20 million to increase production of respiratory masks that protect against the H1N1 influenza virus.

3M’s safety unit benefited from a “tremendous sequential surge” in demand for the masks last quarter because of the spread of H1N1, also known as swine flu, Chief Financial Officer Patrick Campbell said today on a conference call with analysts and investors. The investment will boost mask capacity worldwide by 10 percent.

“We are going to have some sustainable growth that comes from H1N1,” Chief Executive Officer George Buckley said on the call. Demand for the protection is “huge,” he said.

Masks to protect against the H1N1 influenza virus are on back-order through 2009, Buckley said. 3M and Kimberly-Clark Corp. are among the few manufacturers that make respiratory masks sophisticated enough to ward off swine flu, exacerbating shortages. Only masks rated N95 or above, which can filter at least 95 percent of airborne particles, are effective at blocking the virus, according to the U.S. Department of Health and Human Services.

Mask sales helped 3M post second-quarter profit excluding some costs of $1.20 a share, topping the 94-cent average estimate of 14 analysts in a Bloomberg survey. Net income declined 17 percent to $783 million, or $1.12 a share, the St. Paul, Minnesota-based company said in a statement.

3M rose $4.76, or 7.4 percent, to $69.43 at 4:15 p.m., the biggest percentage gain in four months in New York Stock Exchange composite trading. The shares have gained 21 percent this year.

To contact the reporters on this story: Melita Marie Garza in Chicago at mgarza4@bloomberg.net; Jack Kaskey in New York at jkaskey@bloomberg.net.

Last Updated: July 23, 2009 16:20 EDT