because the ip belongs to the company because presumably he developed it during working hours using the company's resources.
No clause or contract is required for this to be the case. It's the default state. It might be different in other countries but I doubt it.
Employees have a "duty of loyalty". https://www.google.com/search?q=employee+duty+of+loyalty
That would seem to include things like this issue. It also includes not competing with your employer.
The idea of any kind of "duty of loyalty" is absolutely laughable in this day and age. Employers have long since rejected any sense of having loyalty to their employees.
Also, if you're going to link to something, at least link to the Wikipedia article on it. Linking to a Google search is pretty dickish.
here's one for California 2016
http://blogs.orrick.com/trade-secrets-watch/2016/01/19/the-d...