Painting particle board is no problem, it just looks like painted particle board.
I'd use a good quality Alkyd Floor Enamel. Brunning and Benjamin Moore both have excelent products for this.
Take the time to be sure that the floor is clean and as dust free as possible and then apply two coats, allowing each to dry per manufacturers directions, And sand lightly between each coat with 150 grit sandpaper and vacuum the dust up. (No primer is nessisary for most floor enamels, besides, most primers aren't suitable to be walked on)You may wish to apply a third coat for good measure. Allow this to dry for at least 24 hrs before foot traffic, and only socks first, shoes after 2 days.