Printing Process Using Specified Azo Dyes
Publication Date: 2003-Apr-13
The IP.com Prior Art Database
Compositions, dyes, processes for making dyes ink sets and printing process using the dyes.
PRINTING PROCESS USING SPECIFIED AZO COMPOUNDS
This invention relates to a printing process, to compounds and processes for their manufacture, to compositions derived therefrom , to cartridges, to printed substrates and to ink sets. Ink jet printing (“IJP”). is a non-impact printing technique in which droplets of ink are ejected through a fine nozzle onto a substrate without bringing the nozzle into contact with the substrate.
There are many demanding performance requirements for dyes and inks used in IJP. For example they desirably provide sharp, non-feathered images having good water-fastness, light-fastness and optical density. The inks are often required to dry quickly when applied to a substrate to prevent smudging, but they should not form a crust over the tip of ink jet nozzles because this will stop the printer from working. The inks should also be stable to storage over time without decomposing or forming a precipitate which could block the fine nozzles.
Direct Black 38 and Direct Black 19 are known colorants for ink jet printing. These dyes comprise a 1-amino-8-hydroxynaphthalene unit.
GB 774,612 describes certain blue to bluish red dyes comprising a 1,8-dihydroxynaphthalene group carrying a tris-azo group on one side only. These dyes are used for the conventional dyeing of leather.
US 1,209,154 describes violet dyes for cotton containing a 1,8-dihydroxy-naphthalene group carrying a tris-azo group on one side only.
Surprisingly it has been found that certain compounds comprising twice-coupled 1,8-dihydroxynaphthalene have outstanding properties as ink jet inks.
According to the present invention there is provided a process for printing an image on a substrate comprising applying thereto a composition comprising a liquid medium and a compound of Formula (1):
each T independently is an azo group;
Q is an optionally substituted, optionally metallised 1,8-dihydroxynaphthyl group; and
L is a divalent organic linker group.
Preferably the composition is applied to the substrate by means of an ink jet printer. The ink jet printer preferably applies the composition to the substrate in the form of droplets which are ejected through a small orifice onto the substrate. Preferred ink jet printers are piezoelectric ink jet printers and thermal ink jet printers. In thermal ink jet printers, programmed pulses of heat are applied to the composition in a reservoir by means of a resistor adjacent to the orifice, thereby causing the composition to be ejected in the form of small droplets directed towards the substrate during relative movement between the substrate and the orifice. In piezoelectric ink jet printers the oscillation of a small crystal causes ejection of the composition from the orifice.