There's enough background for Urahara to be evil/have an alterior motive.
He created the 'solution' to break the boundary between Shinigami and Hollow. So far, there is NO way anyone can do that without the 'solution'. Urahara must have administered it to Ichigo after he loses against Byakuya the 1st time in the real world.
This is a questions that hasn't been answered, even if it hasn't been asked, so it has to be relevant.