Printing inks viscosity ranges

Pan mixers Vertical, rotating paddles, often with planetary motion Mixing, whipping and kneading of materials ranging from low viscosity pastes to stiff doughs Food, pharmaceuticals and chemicals, printing inks and ceramics... 

Print head technology determines inkjet inks major characteristics, the latter being covered in the chapter "Inkjet inks Requirements". A major characteristic, substantially differing from standard printing inks, is the viscosity. While the viscosity of printing inks vary from several hundred up to several thousand cPs (centi Poise) — the viscosity of inks used for inkjet applications is in the range of a few cPs for the SOHO (Small Office and Home) printers and up to 20 cPs for commercial printers using industrial print heads. 

A method was developed to enable high print quality for those applications "heated substrate". The substrate to be printed is heated during the printing process, to temperatures in the 40 to 70°C range. The mechanism which enables high print quality is driven by control of the ink viscosity and is explained in Fig. 8. 

The gravure process is typically chosen because of the printing speeds that can be achieved. To transfer ink at high speed, extremely low viscosity is required. Solvents such as toluene, xylene, and alcohols are often used, sometimes in conjunction with water. Fortunately, many organic polymers are soluble in toluene and xylene. The necessary viscosity range is achievable for pure polymers in solution, unlike the... 

The key solution polymers (resins) used in printing ink are styrene or rosin based. Styrene-a-methylstyrene monomer and acid functional co-monomers (i.e. acrylic or methacrylic acid) comprise the bulk of styrene acrylic solution vehides used in printing ink. Rosin acid reacted with fumaric add gives a tri-functional adduct . The adduct is partially esterified with polyols such as pentaerythritol, glycerin, diethylene glycol, etc. to achieve a range of addity, viscosity, Tg and molecular weight. 

Process Binders Solvent Boiling range/ °C Viscosity Poise Ink thickness/ pm. Print thickness/ pm... 

Jetting reUabiUty also Umits the molecular weight of the binder used. In the vicinity of the nozzle, the more volatile components of ink evaporate. When the resin drops out of solution this wiU cause nozzle blockage. In addition, high molecular weight polymers may lead to viscosities outside the print head range. Polymers used normaUy have a molecular weight below 100 000 and often below 50 000. Common polymers used are vinyl chloride/vinyl acetate copolymers, acryUc resins and polyketone resins. 

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