| 摘要 |
A covert material for printing onto a printing medium is provided, the covert material comprising a covert pigment and a binder encapsulating the covert pigment into a particle, where the binder comprises at least one of cellulose acetate butyrate (CAB), butyral vinyl acetate, acetyl butyrate, and acetate butyrate. Alternatively, the binder comprises at least one of polyester, polyolefin, acetyl butyrate, acetate butyrate, polystyrene copolymer, and polystyrene-polyvinylpyridine. The covert material can comprise additional components, such as ethyl acetate and/or n-propyl acetate. In one embodiment, the covert pigment comprises about 0.5-5% of the covert material. In one embodiment, the binder comprises about 5-30% of the covert material. In one advantageous embodiment, the covert pigment comprises at least 2% of the covert material and the binder comprises about 20-25% of the covert material. The covert material can further comprise at least one of a colorant, a surface additive, and a magnetic particle. The covert material can be part of a toner or ink. In at least some embodiments, the particle can have many different sizes, including sizes greater than 1 micron, greater than 5 microns, and greater than 20 microns. In one embodiment, the covert printing material is constructed and arranged to be printed using a printer having a predetermined resolution, wherein the particle has a size that is substantially the same as the size of a single pixel or dot printed using the predetermined resolution. The covert material can be constructed and arranged to satisfy a predetermined number of the NCITS 322 tests.
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