HOW TO CHOOSE THE INK FOR YOUR PERFECT PRINTING？

There are many factors that affect the quality of corrugated box printing, such as printing equipment, printing plates, R-bak, printing pressure and the suitability of water-based inks for printing. As one of the key factors, it is very important to master the characteristics of water-based inks and the application techniques of water-based printing.

The relationship between the properties &?the suitability of ink in the application

Color: the ultimate goal of printing is to achieve color reproduction.

Color intensity: the main factor affecting the color intensity in printing is the thickness of the ink transferred to the printing plate through the ink transfer device, that is, the amount of ink transfer.

The three attributes of color are hue, brightness and purity.

Hue: is a reaction to the color inherent color phase, is the main difference between color and color.

Brightness: is a reflection of the degree of color light and dark.

Purity: that is, saturation. Is the response to the degree of color close to the natural color light.

The main factors affecting the color

Because of the appearance of color there is the phenomenon of translucency, reactivity and homogeneity (i.e., the phenomenon that two colors match very well under the conditions of a certain same light source and do not match under another light source). Color can be affected by different variables of the viewing conditions (such as the viewing angle, the degree of illumination, the opacity of the glossy ink and the overprinted graphics).

The surface state of the substrate has an effect on the color development of the ink. Such as glossiness, ink absorption, surface color, etc.

Issues such as the thickness of the ink layer and color concentration will cause changes in color shades. The drying time of the ink layer has an effect on the observation and determination of color. Because before the ink dries, the surface of the ink layer on the reflective transmission and light absorption and after drying is different. Dark ink after drying the color is darker, and light ink after drying the color is lighter, which is the law of change of wet and dry ink.

Determination of color

Light (lamp) source: Because there is light before color, the wavelength of light is different, even the same color reflected in the action of different light is also different, so the detection of color, the best use of standard color light source. General standard light sources such as D65 and D50, because it is in the visible spectrum range (360-750 nm) with red, green and blue energy equal characteristics, so that people can easily observe the slight differences in color. Therefore, it is important to use a standard light source if the requirements for color are strict.

Computer detection system, because different colors have their own wavelengths, the computer is based on the wavelengths felt to check out the color, the general computer soft film for CIEL.A.B system (L represents the brightness of color in the white to black range that is the degree of light and dark.) According to the determination of color L.A.B value can only determine the color hue and brightness, but not the purity of the color, (the three attributes of color mentioned earlier) so the actual color inspection still has a 10-20% error, if equipped with L.C.H system, the purity of the color can be measured only 5%-10% error, measured △ E words, the error is only about 3%. Therefore, as long as there is a complete detection system will be able to measure the high quality of color.

Viscosity: the size of the cohesion of the ink, is one of the main indicators of ink.

Determination of viscosity:

For viscosity measurement tools are viscosity rings and stopwatches. The test method is to use the viscosity cup with the specified capacity and leak hole diameter, and the time needed to test the ink flowing out of the viscosity cup until it breaks (calculated with a stopwatch). Because the current application of viscosity cup specifications are not the same, more types, so the results measured by different specifications of the viscosity cup are not the same. At present, most of the viscosity cups used for measuring water-based inks are Japanese RIGOSHA4#CUP, etc.

The control range of water-based ink viscosity

General solid?printing using ink viscosity in 15 seconds -25 (RIGOSHA4# CUP) seconds, the viscosity range of ink leveling good, good adaptability to solid?printing. If the viscosity is too high, the ink is easy to dirty the plate so that prints produce burrs; if the viscosity is too small, affecting the ability of the carrier to drive the color, solid printing has a waterline leakage of white or color intensity is not enough and other phenomena.

Overprint?and small letter print using ink viscosity in 8 seconds -15 seconds (RIGOSHA4 # CUP) is good, the viscosity range of ink flow is good, the reproduction performance of the network is strong, the printed product network clear, clear layers, small deformation, not easy to dirty plate and sticky plate.

Multi-color printing products should meet the premise of overprinting without leakage of white, a reasonable arrangement of the printing color sequence. Control the viscosity and ink layer drying time before and after the color sequence, to ensure that the latter color printing ink color can cover the previous color.

As mentioned above, the size of the viscosity can directly affect the quality of printing?effect. But because of the different printing conditions. In order to control the viscosity of the ink more accurately, the viscosity of the ink should be checked regularly during the printing process. Combined with different viscosity of the printed product effect, record its best value, maintain the viscosity of the best value range for printing.

Drying is also one of the more important indicators of ink, because the drying speed and viscosity can be directly expressed in the quality of printing.

Drying Principle

The drying of general ink includes three ways of volatilization, absorption and reactive curing. The operator must understand the drying principle of ink in detail in order to reasonably deploy the drying time of ink according to the different products or substrates.

Drying speed

Drying too fast, the ink layer is easy to crust, ink is easy to dry attached to the printing plate, resulting in dirty version of the sticky plate, printing is not full and dot unclear, the prints are burrs and other phenomena, to solve this problem can be in the ink in the right amount of slow dry agent adjustment; drying too slow, easy to stick, so that the prints scuffed dirty tor flowers, and even affect the stacked color printing, the problem can be based on the PH value of high and low, the right amount of fast dry agent to adjust or choose a faster dry ink printing.

PH value

Water-based inks contain a certain amount of amine solvent, which is used to control and improve the stability of water-based inks. Therefore, PH value is one of the important indicators to ensure the adaptability of water-based ink. The PH value of water-based ink factory is generally controlled between 8.0~9.5?(25℃). The PH value is measured by PH meter and thermometer. Due to the volatilization of the amine solution in the ink and the influence of the acidity and alkalinity of the substrate, the PH value will change during the printing process. It is recommended that the operator should check the PH value of the ink at regular intervals (preferably within 2?hours). It is recommended that the operator should regularly (preferably within 2 hours) check the PH value of the ink and add the appropriate amount of PH stabilizer to adjust it to ensure a stable printing suitability of the ink.

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