Most employment agreements are such that the company owns it even if it is outside of normal hours. So inventions you come up with on your own time are not yours.
I had this happen to me once. There was a document buried in the mountain of new-hire paperwork which asked me list all of the projects in which I claimed IP rights. All other copyrightable material I created for the duration of my employment was considered property of my employer, even if I used my own time and resources. I signed every other form and left that one unsigned in the middle of the pile. Later, the HR person brought it back to me and informed me that I forgot to sign it. I casually said that I didn't consent to the language in the form. When she asked why, I told her "what I do with company time and company resources is property of the company and what I do with my time and my resources is my property". She was flustered and said she had to consult the legal team. Shortly thereafter she came back with a modified document that agreed with my prior statement and I signed that. The point is, your employer can't make you become a slave - only you have the power to do that. Also, ask a new employer for a copy of the employee agreement before you give notice to your current employer. That will allow you to determine if it's worth leaving your current job if the new employee agreement is too draconian.