Loans to buy into and improve a small co

I have a friend that has been working at his own business; we have sat down many times and talked about improvements that would help the Company. I have been asked many times If I would like to join, I know that he would rather be a behind the scenes person and I love to be in the front office running, meeting, selling, and marketing.
Are there money lenders that would help me out in investing in this company I know it would grow at least 30 – 50 % more in the next year with the right equipment and setup, and being a little savvy helps too. I am not sure if this would count as a small business start up loan or not since I would be investing and work with in one already established. If anyone has any ideas that might help please let me know. It would be the right time of year to invest now!

Have you though about getting a SBA loan or a Gvmt grant