INK FOR WRITING UTENSIL, WRITING UTENSIL, AND METHOD FOR DISCRIMINATING SIGNATURE

摘要

PROBLEM TO BE SOLVED: To obtain an ink which enables a signature to be confirmed as that of the signer by incorporating a substance contg. deoxyribonucleic acid of the signer into the same. SOLUTION: A substance, such as the blood, saliva, hair, nail, skin, or the like, of a signer is incorporated. The ink is prepd. by compounding 1-15 wt.% colorant comprising a dye or pigment, 0.1-10 wt.% deoxyribonucleic acid-contg. substance, and water accounting for the rest. An ultraviolet absorber is pref. incorporated in order to protect deoxyribonucleic acid from the effects of ultraviolet rays. The addition of a chelating agent, such as EDTA, as a sequestering agent for divalent metal ions, e.g. Mg2+, is pref. to suppress the activity of an enzyme capable of decomposing deoxyribonucleic acid. When blood is used, the addition of an anticoagulant is pref. In confirming a signature, an ink contg. a deoxyribonucleic acid-contg. substance of the signer is used for signing; deoxyribonucleic acid is taken out of the signature and subjected to judgment of type; and the comparison with the type of deoxyribonucleic acid of the signer is carried out.