Abstract: A thermal ink which comprises a colour former, a colour developer and a sensitizer, characterised in that the colour former comprises 3-dibutylamino-6-methyl-7-anilinofluoran; the colour developer comprises bisphenol A; and the sensitizer comprises dimethyl terephthalate; and that the ink also comprises at least one pigment. This ink may be used in thermal papers to reduce unwanted discolouration during storage.

Abstract: A method of preparing a thermally printable sheet which comprises providing a substrate comprising a base sheet having at least one surface coated with a layer containing a pigment in solid porous particulate form, and, using a printer, printing onto the coated surface of said substrate, a thermal ink which comprises a colour former, a colour developer and a sensitizer, characterised in that the sensitizer comprises dimethyl terephthalate, and that the ink also comprises at least one pigment. A novel thermally printable sheet suitable for use in such method is also provided.

Abstract: A security feature is imparted to record material for use in pressure-sensitive copying paper systems by dyeing the surface sizing composition and/or other coatings present in the paper and then applying the dyed composition or coating in a manner such as to produce an uneven coating pattern, for example a film-split pattern. The dye accentuates the coating pattern and produces a visual effect which is difficult to replicate without access to a papermaking or paper coating machine, and which has a distinguishably different appearance from that of the opposite surface of the reccord material. The invention is particularly suited for use with a Billblade coater which applies a dyed surface sizing composition to one surface of the paper and a pigment coating to the other surface or with a metered size press coater.