Printing Ink Suitability

Substrate, printing ink and other materials and printing conditions match, suitable for printing operations, called printing suitability.

The printing suitability of ink, ink and printing conditions to match, suitable for printing performance. Mainly viscosity, adhesion, thixotropy, dryness and so on. Ink in the flow of the internal friction characteristics, called ink viscosity, measure ink viscosity of the physical quantity, called ink viscosity.

The viscosity of the ink can be measured with a viscometer, commonly used viscometers are parallel plate viscometer, rotational viscometer, Lare viscometer.

The faster the speed of the printing press, the greater the fluidity of the ink required, the smaller the viscosity.

The viscosity of the ink can be adjusted with ink blending oil or ink thinner. Ink from the ink hopper to the ink roller, printing plate, (blanket) substrate surface transfer, ink film is first split, and then transfer, ink film in this dynamic process to prevent the ink film rupture ability, called ink adhesion. Measurement of ink adhesion physical quantity, called the ink Tack value.

Tack value of ink can be measured by ink adhesion meter.

Printing process, if the ink adhesion and the properties of the substrate, printing conditions do not match, then the paper will occur powder, lint, ink overprinting bad, printing plate dirty printing faults.

The adhesion of the ink can be adjusted with the removal of adhesive or ZY ink additives. At a certain temperature, the ink by stirring or applying mechanical force, the fluidity is improved, the viscosity decreases; after standing, the fluidity and become bad, the viscosity rises, this property is called the thixotropy of the ink.

Printing process, if the ink of the thixotropy of bad, will occur "under the ink is not smooth", uneven ink transfer, dot serious expansion and other printing faults. In order to prevent the occurrence of these failures, the need to use the ink shovel often stirring ink in the hopper or the installation of ink in the hopper ink stirrer from time to time to stir the ink. Ink drying is more complex, there are mainly the following three forms.

Penetration drying. Linking material in the ink, part of the penetration into the substrate, the other part of the pigment and pigment together with the adhesion on the surface of the substrate and drying. High-speed web printing machine using non-thermosetting rotary ink, generally to penetration drying, mainly printing newspapers, periodicals.

Oxidative polymerization drying. Linking material in the ink and the oxygen in the air polymerization reaction, in the surface of the substrate film and dry. Offset printing glossy resin ink, bright colors, good gloss, mainly oxidation polymerization drying, for printing high-grade fine offset products.

Volatile drying. Part of the linking material in the ink, volatilization to the air, the remaining linking material together with the pigment fixed on the surface of the substrate and dry. Gravure printing ink is a volatile solvent for the linking material, the linking material used is harmful to the human body of benzene, xylene. Flexographic printing, reducing the pollution of the environment, very promising. Volatile drying ink is particularly suitable for printing no absorbent film materials, such as plastic film, metal foil, etc..

In addition to this, the ink drying there are ultraviolet, infrared, heat curing and other forms.

Many ink drying, often a combination of two drying forms to complete the ink film drying. For example, sheet-fed fast-setting offset inks, suitable for printing general offset products, it is the use of a combination of penetration and oxidative polymerization for drying.

Printing process, if the ink drying is not good, will cause the back of the printed sheet rubbing dirty, sticky pages, ink film without luster, ink "crystallization" and other printing faults.

In order to accelerate the drying speed of ink, can be added to the ink drying agent. Commonly used drying agents are: cobalt dry oil, manganese dry oil, lead dry oil. In order to reduce the drying speed of the ink, you can add drying inhibitors in the ink.