| 摘要 |
<p>An invisible ink has been discovered that utilizes an invisible or almost invisible substituted phthalocyanine dye in combination with selected waxes and resins. The resulting ink is one that has use in thermal printing and is transparent or almost transparent in white light, but is responsive to infra-red light in the range of 720 to 1000 nm. The preferred waxes are polyethylene wax, natural paraffin wax and carnauba wax, and the preferred resin is ethyl vinyl acetate polymer.</p> |
