Use [drupal_add_css][1] with the option 'browsers'.

    drupal_add_css(
      path_to_theme() . '/ie.css',
      array(
        'browsers' => array(
          'IE' => 'lte IE 9',
          '!IE' => FALSE
        )
      )
    );

You should add this function call in your theme's template.php file through template_preprocess_html like this:


    function MYTHEME_preprocess_html(&$vars){
      drupal_add_css(
          path_to_theme() . '/css/ie.css',
          array(
            'browsers' => array(
              'IE' => 'lte IE 9',
              '!IE' => FALSE
            )
          )
        );
    }




  [1]: https://api.drupal.org/api/drupal/includes%21common.inc/function/drupal_add_css/7