The ability of substrates, printing inks, and other materials to match printing conditions and be suitable for printing operations is called printability.
The printing suitability of ink, refers to the water-based printing ink and printing conditions match, suitable for the performance of printing operations.There are mainly viscosity, adhesion, thixotropy, drying and so on.
Ink in the flow of internal friction characteristics, called the viscosity of ink, ink viscosity measurement of physical quantity, called the viscosity of ink.
Ink viscosity can be measured with a viscometer, commonly used viscometer has a parallel plate viscometer, rotational viscometer, laray viscometer, etc.
The higher the speed of the printing press, the greater the fluidity of the ink required, the smaller the viscosity.
Ink viscosity, can be adjusted with ink or ink thinner.
Gravure water - based plastic table printing ink
The adhesion of ink
Ink from the ink bucket to the roller, plate, (blanket) substrate surface transfer, ink film first split, and then transfer, the ink film in this dynamic process shows the ability to prevent the rupture of the ink film, called the adhesive ink.Tack value, a measure of Tack of ink.
Tack's value of the ink can be measured using an ink Tack meter.
In the process of printing, if the adhesion of ink and substrate properties, printing conditions do not match, will occur paper powder, hair, ink overprint poor, dirty printing plate printing faults.
Ink adhesion, can be used to remove adhesive or ZY ink additives for adjustment.
Thixotropy of ink
At a certain temperature, the ink by stirring or applying mechanical forces, the fluidity improved, viscosity decreased;After the static flow and become bad, viscosity rise, this property is called the thixotropy of ink.
In the process of printing, if the ink thixotropy is bad, it will occur "down ink is not smooth", ink transmission is not uniform, dot serious expansion and other printing faults.In order to prevent the occurrence of the above faults, need to use the ink shovel often stir ink in the ink bucket or in the ink bucket installed ink agitator from time to time stir ink.
Gravure water-based paper ink
Drying of ink
Ink drying is more complex, mainly in the following three forms.
Osmotic drying.Gravure water-based paper and ink binders, some of them permeate into the substrate, another part of the pigment with a solid on the substrate surface and dry.The non-thermosetting rotary ink used in high-speed web printing machines is mainly used for osmotic drying, mainly for printing newspapers and periodicals.
Oxidative polymerization drying.Ink linker and oxygen in the air polymerization reaction in the substrate surface film and dry.Offset printing gloss resin ink, bright color, good gloss, mainly oxidation polymerization drying, used for printing high-grade fine offset printing products.
Volatile drying.Ink in part of the linker, volatile to the air, the rest of the linker and pigment on the substrate surface and dry.Gravure printing ink is a volatile solvent for the linker, the linker is harmful to human health benzene, xylene.Flexographic printing, reducing the environmental pollution, has a bright future.Volatile dry ink is particularly suitable for printing non - absorbent film materials, such as plastic film, foil, etc.
In addition, ink drying and ultraviolet, infrared, heat curing and other forms.
Many ink drying, often two drying forms combined to complete the ink film drying.For example, sheet fastening offset inks, suitable for general offset printing products, are dried by a combination of osmosis and oxidative polymerization.
In the printing process, if the ink is dry, it will cause the back of the printing sheet dirty, sticky pages, ink film luster, ink "crystallization" and other printing faults.
In order to speed up the ink drying speed, can be added in the ink drying agent.Commonly used drying agents are: cobalt drying oil, manganese drying oil, lead drying oil, etc.In order to reduce the drying speed of ink, ink can be added to the drying inhibitor.