Section 3--406. Negligence  Contributing  to  Alteration or Unauthorized Signature. Any person who  by  his  negligence  substantially  contributes  to  a  material alteration of  the  instrument  or  to  the  making  of  an  unauthorized signature is precluded from  asserting  the  alteration  or  lack  of authority against a holder in due course or against a drawee or  other payor who pays the instrument in good faith and in accordance with  the reasonable commercial standards of the drawee's or payor's business.