$re = '/[^&]_*\s*(SF)*\d{8}/m';
$str = '_zz&69050398_5d147597dd4aca00014351d9_zz sf 76064603RPL_Import_Create
_zm&69396284_5d165ed60198d60001fbef9a_75946292_Import
_aa&69385775_5d15782bdd4aca0001435432_supplier_info_import_template
_aa&68936210_5d16581add4aca00014355e9_76005473 RPL_Import_Create_Stand_to_Package
_ac&68728692_5d18fa52dd4aca00014356dd_SF 76113839 Copy of Generic_Export_AdvancePR_result - 2019-06-30T200450.090';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php