How to introduce my paint product to companies

For starters, be prepared to tell them

About yourself and why they should trust you,
What companies are using and satisfied with your product,
Why your product is better than Sherwin-Williams, PPG, Behr, etc.
Why it's a better value than those other products,
What is different about your product

These days? The best website wins. Mailings are a thing of the past, as are emails and phone calls.
Locally, a large picture postcard is OK, with the more info on it the better.

You don't even say whether you are a wholesaler, manufacturer, dealer, or what.

Give them free samples to try.

I would brand your company. Introduce it to people, make ads maybe write about it in a blog.