Organic solvent based ink for invisible marking/identification

An ink composition for use in an ink jet printer, said ink comprising

• a) from about 1 and about 10 weight percent of at least one organic solvent soluble polyester comprising:
• i) 100 mole percent of monomer residues of at least one dicarboxylic acid selected from C.sub.6 -C.sub.12 aliphatic dicarboxylic acids, 1,4-cyclohexane-dicarboxylic acid and C.sub.3 -C.sub.12 oxa-aliphatic dicarboxylic acids which contain one or more oxygen atoms in the aliphatic chain and mixtures thereof;
• and
• ii) 100 mole percent monomer residues of at least one diol selected from diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycols having number average molecular weights from about 100 to about 10,000 and polypropylene glycols having number average molecular weights of from about 200 to about 6,000, wherein said polyester has from about 0.1 ppm by weight to about 10% by weight of at least one thermally stable near infrared fluorophore copolymerized therein and the diacid residues and diol residues total 200 mole percent;
• b) between about 1 and about 5 weight percent of a binder selected from a cellulose ester or a condensed phenolic resin;
• c) between about 0.01 and about 0.5 weight percent of a corrosion inhibitor;
• d) between about 0.50 and about 1.0 weight percent of an organic solvent soluble electrolyte;
• and
• e) the remainder of said composition consisting of at least one C.sub.4 -C.sub.6 aliphatic ketone, at least one C.sub.4 -C.sub.6 aliphatic ester, or a combination thereof, wherein all weight percentages are based on the total weights of the constituents a-e.

A method for detecting an article having a fluorescing ink printed thereon, said ink having detectable fluorescence when exposed to near infrared radiation, said method comprising the steps of:

• a) applying to a surface of said article a fluorescing ink comprising:
• i) from about 1 and about 10 weight percent of at least one non-sulfo containing, organic solvent soluble polyester having from about 0.1 ppm by weight to about 10% by weight of at least one thermally stable near infrared fluorophore copolymerized therein;
• ii) between about 1 and about 5 weight percent of a binder selected from a cellulose ester or a condensed phenolic resin;
• iii) between about 0.01 and about 0.5 weight percent of a corrosion inhibitor;
• iv) between about 0.50 and about 1.0 weight percent of an organic solvent soluble electrolyte;
• and
• v) the remainder of said composition consisting of at least one C.sub.3 -C.sub.6 aliphatic ketone, at least one C.sub.3 -C.sub.6 aliphatic ester, or a combination thereof, wherein all weight percentages are based on the total weights of the constituents (i)-(v);
• b) using an excitation means to subject said fluoresceing ink to an excitation radiation whereby said fluoresceing ink produces a detectable fluorescence;
• and
• c) using a detection means to detect said detectable fluorescence.

A composition of matter comprising:

• a. between about 1 and about 10 weight percent of at least one non-sulfo containing, organic soluble polyester having from about 0.1 ppm by weight to about 10% by weight of at least one thermally stable near infrared fluorophore copolymerized therein;
• b. between about 1 and about 5 weight percent of an organic solvent polymeric binder resin selected from the group consisting of condensed phenolic, polyketones, polyamides and polyurethanes;
• c. between about 0.01 and about 0.5 weight percent of a corrosion inhibitor;
• d. between about 0.50 and about 1.0 weight percent of an organic soluble electrolyte;
• and
• e. the remainder of said ink consisting of an organic solvent comprising at least 40 weight percent of at least one lower aliphatic alcohol and up to 60 weight percent of at least one compound selected from the group consisting of a C.sub.3 -C.sub.6 aliphatic ketone, a C.sub.3 -C.sub.6 aliphatic ester and mixtures thereof, with all of the weight percentages in a-d being based on the total weights of components a-e.

A method for detecting an article having a fluorescing ink printed thereon, said ink having detectable fluorescence when exposed to near infrared radiation, said method comprising the steps of:

• a) applying to a surface of said article a fluorescing ink comprising:
• i) between about 1 and about 10 weight percent of at least one non-sulfo containing, organic soluble polyester having from about 0.1 ppm by weight to about 10% by weight of at least one thermally stable near infrared fluorophore copolymerized therein;
• ii) between about 1 and about 5 weight percent of an organic solvent polymeric binder resin selected from the group consisting of condensed phenolic, polyketones, polyamides and polyurethanes;
• iii) between about 0.01 and about 0.5 weight percent of a corrosion inhibitor;
• iv) between about 0.50 and about 1.0 weight percent of an organic soluble electrolyte;
• v) the remainder of said ink consisting of an organic solvent comprising at least 40 weight percent of at least one lower aliphatic alcohol and up to 60 weight percent of at least one compound selected from the group consisting of a C.sub.3 -C.sub.6 aliphatic ketone, a C.sub.3 -C.sub.6 aliphatic ester and mixtures thereof, with all of the weight percentages in a-d being based on the total weights of components a-e;
• b) using an excitation means to subject said fluoresceing ink to an excitation radiation whereby said fluorescing ink produces a detectable fluorescence;
• and
• c) using a detection means to detect said detectable fluorescence.