<ACCESSION-NUMBER>0001628280-18-001978 <TYPE>10-K <PUBLIC-DOCUMENT-COUNT>122 <PERIOD>20171231 <FILING-DATE>20180221 <DATE-OF-FILING-DATE-CHANGE>20180221 <FILER> <COMPANY-DATA> <CONFORMED-NAME>LYDALL INC /DE/ <CIK>0000060977 <ASSIGNED-SIC>3714 <IRS-NUMBER>060865505 <STATE-OF-INCORPORATION>DE <FISCAL-YEAR-END>1231 </COMPANY-DATA> <FILING-VALUES> <FORM-TYPE>10-K <ACT>34 <FILE-NUMBER>001-07665 <FILM-NUMBER>18628970 </FILING-VALUES> <BUSINESS-ADDRESS> <STREET1>ONE COLONIAL RD <STREET2>P O BOX 151 <CITY>MANCHESTER <STATE>CT <ZIP>06045-0151 <PHONE>2036461233 </BUSINESS-ADDRESS> <FORMER-COMPANY> <FORMER-CONFORMED-NAME>COLONIAL BOARD CO <DATE-CHANGED>19700115 </FORMER-COMPANY> </FILER>