If you're in Osaka on business, there's a good chance that you're attending an exhibition or conference at the Asia Pacific Trade Center. You don't have to be working to enjoy a trip to the facilities, though, since the center regularly features fun events intended for all ages.
Check the calendar beforehand to see what events are coming up. You may have a chance to play with reptiles, eat food from all over Japan, or something else fun or even intellectually stimulating.
Past attractions have included made-to-scale dinosaurs
Check the calendar before you go as all the events are on here
Commonly referred to as ATC
From Osaka/Umeda Station, take the Osaka Loop Line to Bentencho Station. Then transfer to the Chuo Line and ride to Cosmo Square Station. From there, it's a 15-minute walk following the prominently displayed signs.
The ATC facilities also house the O's shopping center, where you can find food, retail shops and more.
The ATC calendar is only available in Japanese, but a little browsing should give you some idea of what's happening on any given day.