Here is a great way to prevent web pages from being printed. You simply set the CSS media type (@media) to print and change the body display to none as shown below.

/*inside print.css*/
body { display:none }

Link to CSS file
<link rel="stylesheet" type="text/css" href="print.css" media="print" />

Or per page if you only need to block a few pages:

<style type="text/css"> @media print { body { display:none } } </style>

You can be more creative with this:  for instance if you don’t want certain parts of a page to print then you can simply give an element a class name or id and set it’s display to none inside the print.css file.

This is not a fool proof method to prevent a page from being printed but it is a reasonably good fix to the issue.