Ink-Jet Inks

Although acid dyes have been traditionally used for the coloration of ink jet inks, phthalocyanine pigments are now replacing these dyes, especially in industrial applications such as signs, advertisements and textiles, to improve their water resis- 

From a chemical perspective, this colorant is particularly interesting. The ligands on the third coordination site of aliuninum phthalocyanines are usually very reactive, and are readily exchanged by other ligands or nucleophiles. For example, the well-known chloroaluminum phthalocyanine is in equilibrium with two other species, hydroxyaluminum phthalocyanine and a mu-oxo dimer, in the basic aqueous media as shown below. 

Kodak s aluminum phthalocyanine is formed as the dimer structure by using a bidentate ligand, bis(diphenylsiloxy) dianion, as the third ligand. This bulky and hydrophobic ligand may prevent exchange reactions in aqueous ink systems. 

Today s requirements for dispersibility and dispersion stability of pigment-base ink jet inks require an extremely high level of performance. Dainippon Ink and Chemicals has developed new microencapsulation technologies for the solution of such problems [5]. Their microencapsulated pigments exhibit concentrated polymer layers on the pigment surfaces. The encapsulation polymers used are basically methacryhc acid-methacrylate ester copolymers. 

In addition, microencapsulation treatments add excellent resistance toward water-soluble organic solvents in pigment dispersions, compared with dispersions employing commercially available polymeric dispersants, e.g., styrene-maleic anhydride copolymers. 

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The principal physical properties influencing ink performance ate surface tension and viscosity. High surface tension is desired for good droplet formation and capillary refill in dtop-on-demand ink jet. Low viscosity is desired because less energy is required to pump and eject ink. Conductivity is also an important parameter. Continuous ink-jet inks must have some conductivity to allow for charging. Low conductivity is generally preferred for impulse, particularly thermal ink jet, because excess ions can cause corrosion of the printhead. 

To address this problem water-insoluble latex copolymers containing the covalently bounded dye /V-(2,4-dinitropheny I)-1,4-pheny lene-diamine have been prepared. When printed as ink jet ink, latex particulates formed a hydrophobic print film on the media surface, thereby entrapping and protecting the colorant within the film. The process for preparing these agents consisted of initially forming the Diels-Adler adduct with furan and maleimide followed by a transimidation with 3-amino-1-propanol. 

Solvent dyes for solvent based ink-jet inks and hot melt ink-jet systems are selected 1 2 chromium or cobalt complex azo (C.I. Solvent Yellow 83 1 [61116-27-6], C.I. Solvent Red 91 [61901-92-6]), anthraquinone (C.I. Solvent Blue 45 [37229-23-5]), or phthalocyanine (C.I. Solvent Blue 44 [61725-69-7]) dyes. 

In developing ink-jet printing devices a decisive task is associated with the formulation of inks. Basically, there are three types of ink-jet inks aqueous, solvent, and hot melt. The choice of ink depends on the ink-jet technology used. Aqueous... 

General features of ink jet inks influencing print quality and printer compatibility are summarized in Table 5.15. 

Similar to ink-jet inks, aqueous drawing and writing inks contain water miscible cosolvents as humectants or moisturizers (e.g., glycols, glycerin, or sorbitol), which stabilize the ink in the pen and at the nib. Typically, biocides and tensides are added to the ink formulation. 

A major improvement in permanence of ink-jet prints in recent years has been due to tailoring pigment dispersions for both solvent and water based ink jet inks [18], These pigment containing inks are primarily used for outdoor applications. 

Wong R, Hair ML, Croucher MD. (1988) Sterically stabilized polymer colloids and their use as ink-jet inks. / Imag Technol 14 129-131. 

Belmont JA, Johnson JE, Adams CE. (1996) Ink jet ink formulations containing carbon black products, US5571311. 

Moffat JR, Bedford ET, Lauw HP. (1999) Ink-jet inks for improved print quality, US5935309. 

Wickramanayake P, Parazak DP. (1996) Bleed-alleviated, waterfast, pigment-based ink-jet ink compositions, US5531816. 

Dynamic Sorption of Ink Jet Ink Drops on Commercial Papers. Drying times (t ) and various parameters measured or derived from contact line spreading, profile development and penetration data for the various systems studied are summarized in Table I. A wide variation occured in the values of tj among the various papers studied. The maximum deviations in tdetailed contact line and profile analysis suggest that these deviations result from the structural variability in paper rather than drop-to-drop volume variations. This was substantiated by the marked variations in the final image shape observed among several drops printed on the same paper sample. 

A wide variation in the rate of absorption drying and image quality of an aqueous ink jet ink was apparent among the commer-... 

Aluminum-modified silica sol with a particle size of 12 nm in a pigmented ink-jet ink formulation gave a print with improved optical density and superior rub resistance compared with a reference ink [48]. 

The above ink-jet ink exhibited good adhesion to PVC and dried without a need for external heat. 

Chakvattanatham, K., Phattanarudee, S., Kiatkamjomwong, S., 2010. Anionically surface-modified pigment/binder ink jet inks for silk fabric printing. Pigm. Resin Technol. 39 (6), 327-341. Available at http //www.emeraldinsight.eom/10.1108/03699421011085821 (accessed 18.08.12). 

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