Private Search Engine

What is the name of your state (only U.S. law)? Illinois

I want to create a search service that companies can use on electronic books (pdfs) that they have purchased. It would be private to the specific company, not open to the public. Is there any way in which this would infringe on copyright for the pdf owners?

Possibly.

If you are planning on starting a new business enterprise, your wisest course of action is to consult with an attorney in your area and go over all of the specifics involved, prior to investing a lot of time, energy and money into this enterprise. There will be more laws than copyright and trademark laws to consider.

Good luck.