Phthalocyanine based inks with absorption maxima in the near infra-red and visible spectrum
AssigneeAvecia Limited
InventorJames Stanley Campbell
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Abstract
The invention provides an ink composition comprising a charge generating material and a medium wherein the charge generating material absorbs radiation in both the near infra-red and visible regions of the electromagnetic spectrum. Also provided is an electrophotographic toner composition comprising a binder resin and the charge generating material. The compositions are useful in, for example, security marking wherein the composition is printed on an article or substrate. Methods of establishing the authenticity of an article or substrate are also provided which comprise detecting an absorption of infra-red radiation by the charge generating material.
Claims25
In a security method comprising application of an ink composition, the improvement wherein the composition comprises a charge generating material and a medium wherein the charge generating material has an absorption maximum in each of the near infra-red region from 700 to 1500 nm and visible region from 400 to 700 nm of the electromagnetic spectrum and is a compound selected from the polymorph type X form of metal free phthalocyanine, the polymorph type Y form and Phase I & II forms of titanyloxy phthalocyanine, the polymorph Phase II form of vanadyloxy phthalocyanine, and the polymorph Phase V forms of hydroxygallium phthalocyanine and methoxygallium phthalocyanine and wherein the charge generating material acts as a colorant of the composition.
In a security application of an ink composition, the improvement wherein the composition comprises a charge generating material and a medium wherein the charge generating material has an absorption maximum in each of the near infra-red region from 700 to 1500 nm and visible region from 400 to 700 nm of the electromagnetic spectrum, wherein the charge generating material is the only colorant of the ink.
A method of establishing the authenticity of an article or substrate which has been marked with an ink composition, the ink composition comprising a charge generating material and a medium wherein the charge generating material has an absorption maximum in each of the near infra-red region from 700 to 1500 nm and visible region from 400 to 700 nm of the electromagnetic spectrum, the method comprising detecting a characteristic absorption of near infrared radiation by the mark and further comprising comparing the characteristic absorption of near infrared radiation with an absorption of radiation in the visible range, the charge generating material acting as a colorant of the ink composition.
Dependencies are inferred from the claim text.