3M Co. has reached an inventor's milestone by accumulating 100,000 patents worldwide.

The Maplewood-based company, which does business all over the world, must obtain patents in different countries to protect its inventions, which range from medical adhesives to reflective traffic signs to films that enhance liquid crystal displays. A recent addition of 52 patents pushed it past the 100,000 mark.

"We celebrate this important milestone, and honor all of the scientists whose inventions have contributed to the success of 3M," Fred Palensky, the company's executive vice president and chief technology officer, said in a statement.

The growth of 3M's worldwide patent portfolio coincides with an explosion in international patent filings following a drop in 2009 at the height of the world financial crisis. About 2.35 million patent applications were filed worldwide in 2012, the most recent year for which statistics have been compiled by the World Intellectual Property Organization. Patent filings worldwide grew 9.2 percent that year, the fastest growth recorded in the previous 18 years.

3M is the largest producer of patent-winning innovations in Minnesota, but it is dwarfed by some other U.S. and international firms.

Last year, 3M was awarded 644 U.S. patents, far behind IBM's 6,791, which were the most received by any company.

During the 25 years from 1989 through 2013, 3M ranked 54th among corporations awarded U.S. patents. 3M obtained 7,491 U.S. patents during that period, compared to 76,402 for No. 1-ranked IBM. Among other big tech firms, Microsoft was No. 9 with 25,241 and Apple No. 51 with 7,595. Fridley-based Medtronic was No. 75 with 4,676.

3M, which obtained its first patent in 1924, annually obtains about 3,000 new patents from around the world.

"Patents are critical to protecting our innovation and significant investments in research and development," Palensky said. 3M spends nearly 6 percent of its approximately $30 billion in annual sales on research and development.

Steve Alexander • 612-673-4553