new WP_User_Query

$administrator_ids =  new WP_User_Query( array( 'role' => 'administrator' ) );
                $admins = $administrator_ids->get_results();
                $admin_ids = array();
                foreach($admins as $admin) {
                    $admin_ids[] = $admin->ID;
                }
                $args2 = implode(',', $admin_ids);
                // echo $args2