I usually use something like this:
<a href="#" onClick="window.open('files/ingredients/{$product.productcode}.html','','scrollbars=no,res izable=no,width=400,height=300,menubar=no,toolbar= no');return false;" target="_blank"> ingredients</a>
That will open a file in the files/ingredients folder that is named for the sku of the product. So if your sku is 100, you would create a file called 100.html and put it in the files/ingredients folder (which you will need to create). Adjust the width and height according to what your html file format is.