Process for producing an image on a substrate

Details Process for producing an image on a substrate Process for producing an image on a substrate

1998-10-02

2001-09-25

Barlow, John (Department: 2853)

Incremental printing of symbolic information

Ink jet

Fluid or fluid source handling means

C347S100000

Reexamination Certificate

active

06293667

ABSTRACT:

This invention relates to, an ink jet printing (“IJP”) process and to acid papers printed with a reactive dye.
There are many demanding performance requirements for images formed by IJP. Ideally such images are sharp and have good water-fastness, light-fastness and optical density. The requirement for high light-fastness is particularly important for images used on outdoor posters and bill boards because these are exposed to direct sunlight for long periods of time.
Reactive dyes are known in the textile field for the exhaust dyeing of cotton, jute, hemp, flax and the like. In this dyeing process the reactive dye is applied in conjunction with alkali and salt at a temperature of about 80° C.
We have now found that images formed by printing reactive dyes onto acid papers have good light fastness, particularly when compared to the same dyes printed onto other papers.
According to the present invention there is provided a process for producing an image on a substrate comprising printing an ink onto the substrate, characterised in that the ink contains a reactive dye the substrat is an acid paper and the printing is performed by an ink jet printer.
Preferred reactive dyes comprise one or more chromophore and one or more cellulose reactive groups.
Preferred chromophores are azo (preferably monoazo and disazo), anthraquinone, triphenodioxazine, formazan and phthalocyanine chromophores. Preferred cellulose reactive groups are halotriazine groups, especially chloro- or fluoro-triazine groups, vinylsulphone or sulphatoethylsulphone groups and halopyrimidine groups. More preferably the cellulose reactive groups are selected from chloro-triazine, fluoro-triazine, fluoro-pyrimidine and chloro-pyrimidine groups, especially chloro-triazines.
Especially preferred reactive dyes comprise one or more azo, anthraquinone, triphendioxazine, formazan or phthalocyanine chromophore and one or more chlorotriazine group.
Suitable examples of reactive dyes include all those listed in the Colour Index International. More specifically, preferred examples of reactive dyes include C.I. Reactive Red 1, 3, 3:1, 13, 24, 29, 31, 43, 45, 58, 74, 85, 120, 125, 141, 151, 152, 185, 188, 190 and 204; C.I. Reactive Violet 1, 2, 3, 24, 35, 36 and 38; C.I. Reactive Yellow 3, 18, 36, 45, 56, 80, 81, 84, 85, 95, 135, 136 139, 142, 145 and 157; C.I. Reactive Black 8, 10, 45 and 31; C.I. Reactive Blue 1, 2, 5, 7, 15, 41, 47, 49, 67, 71, 75, 99, 168, 171, 233 and 291; and C.I. Reactive Orange 4, 12, 13, 20, 35, 38, 46, 66, 73, 95 and 99.
It is especially preferred that the reactive dye is a dye of the Formula (1) to (13) as described on pages 2 to 12 of WO 98/29513 which are incorporated herein by reference thereto.
The reactive dye used in the ink has preferably been purified by removal of substantially all of the inorganic salts and by-products resulting from its synthesis. Such purification assists in the preparation of a low viscosity aqueous solution suitable for use in an ink jet printer. The dyes may be purified using conventional techniques, for example reverse osmosis, dialysis, ultrafiltration or a combination thereof.
The ink used in the process preferably comprises:
(a) from 0.01 to 30 parts in total of one or more reactive dye(s); and
(b) from 70 to 99.99 parts of a liquid medium;
wherein all parts are by weight and the number of parts of (a)+(b)=100.
The number of parts of component (a) is preferably from 0.1 to 20, more preferably from 0.5 to 15, and especially from 1 to 5 parts. The number of parts of component (b) is preferably from 99.9 to 80, more preferably from 99.5 to 85, especially from 99 to 95 parts.
Preferably component (a) is completely dissolved in component (b). Preferably component (a) has a solubility in component (b) at 20° C. of at least 10%. This allows the preparation of concentrates which may be used to prepare more dilute inks and reduces the chance of the dye precipitating if evaporation of the liquid medium occurs during storage.
Preferred liquid media include water, a mixture of water and an organic solvent and an organic solvent free from water.
When the medium comprises a mixture of water and an organic solvent, the weight ratio of water to organic solvent is preferably from 99:1 to 1:99, more preferably from 99:1 to 50:50 and especially from 95:5 to 80:20.
It is preferred that the organic solvent present in the mixture of water and organic solvent is a water-miscible organic solvent or a mixture of such solvents. Preferred water-miscible organic solvents include C
1-6
-alkanols, preferably methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, n-pentanol, cyclopentanol and cyclohexanol; linear amides, preferably dimethylformamide or dimethylacetamide; ketones and ketone-alcohols, preferably acetone, methyl ether ketone, cyclohexanone and diacetone alcohol; water-miscible ethers, preferably tetrahydrofuran and dioxane; diols, preferably diols having from 2 to 12 carbon atoms, for example pentane-1,5-diol, ethylene glycol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol and thiodiglycol and oligo- and poly-alkyleneglycols, preferably diethylene glycol, triethylene glycol, polyethylene glycol and polypropylene glycol; triols, preferably glycerol and 1,2,6-hexanetriol; mono-C
1-4
-alkyl ethers of diols, preferably mono-C
1-4
-alkyl ethers of diols having 2 to 12 carbon atoms, especially 2-methoxyethanol, 2-(2-methoxyethoxy)ethanol, 2-(2-ethoxyethoxy)-ethanol, 2-[2-(2-methoxyethoxy)ethoxy]ethanol, 2-[2-(2-ethoxyethoxy)-ethoxy]-ethanol and ethyleneglycol monoallylether; cyclic amides, preferably 2-pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, caprolactam and 1,3-dimethylimidazolidone; cyclic esters, preferably caprolactone; sulphoxides, preferably dimethyl sulphoxide and sulpholane. Preferably the liquid medium comprises water and 2 or more, especially from 2 to 8, water-soluble organic solvents.
Examples of further suitable ink media comprising a mixture of water and one or more organic solvents are described in U.S. Pat. Nos. 4,963,189, 4,703,113, 4,626,284 and EP 4,251,50A.
When the liquid medium comprises an organic solvent free from water, (i.e. less than 1% water by weight) the solvent preferably has a boiling point of from 30° to 200° C., more preferably of from 40° to 150° C., especially from 50 to 125° C. The organic solvent may be water-immiscible, water-miscible or a mixture of such solvents. Preferred water-miscible organic solvents are any of the hereinbefore described water-miscible organic solvents and mixtures thereof. Preferred water-immiscible solvents include, for example, aliphatic hydrocarbons; esters, preferably ethyl acetate; chlorinated hydrocarbons, preferably CH
2
Cl
2
; and ethers, preferably diethyl ether; and mixtures thereof.
The organic solvent free from water may be a single organic solvent or a mixture of two or more organic solvents. It is preferred that when the medium is an organic solvent free from water it is a mixture of 2 to 5 different organic solvents. This allows a medium to be selected which gives good control over the drying characteristics and storage stability of the ink.
The ink preferably has a concentration of less than 100 parts per million, more preferably less than 50 parts per million, in total of halide ions and divalent and trivalent metals. This reduces nozzle blockage in ink jet printing heads, particularly in thermal ink jet printers.
The ink jet printer preferably applies the ink to the acid paper 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 ink in a reservoir by means of a resistor adjacent to the orifice, thereby causing the ink to be ejected in the form of small droplets directed towards the acid paper during relative movement between the acid paper and the orifice. In piezoelectric ink jet printers the oscillation of a small cry

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