On the Adjustment of Ink Printing Suitability (I)

Abstract: This article starts with the structure and properties of water-based inks, describes the ink mixing techniques and the problems to be paid attention to when adjusting the ink, and thus makes a brief introduction to the printability adjustment of ink.

Keywords: ink, printability, ink tone, quality suitability

1 Introduction

The so-called ink printability means that the ink is transferred to the surface of the printing object under a certain printing pressure at a certain printing speed with a certain printing speed. After the printing film is dried, it is fixed on the surface of the printing object to express the desired printing effect. performance.

The printability of the ink includes both the suitability of the print job and the suitability of the print quality. The suitability of the print job of the ink relates to the ink and the corresponding version, machine speed, press and printing object, so as to ensure that the ink can be transferred from the ink drum → Ink fountain → ink roller → printing plate → smooth transfer of printing objects; ink printing quality adaptability refers to the fixation of the ink film transferred to the surface of the printing object, drying speed, color and gloss, fastness, and resistance after film formation. Various properties such as resistance to ensure printing effect.

We often refer to the aspect of the color effect expressed by the ink as the ink color, and other aspects other than the ink color that are related to the printability of the ink are called ink properties.

The ink printing suitability is mainly to solve the optimal matching between ink and ink and printing effect. Due to the particularities of ink structure, printing plate type, printing object, and use of printed materials, the problem of incompatible ink and ink properties and printing jobs and printing quality is more prominent in the practical use of water-based inks. The deployment principles and methods are discussed.

2, the structure and properties of ink

The most prominent feature of ink is: the ink can be mixed with water before drying. Once the ink is dried, it can not be dissolved in water and ink, which means that the ink has water resistance. Therefore, special attention should be paid when printing: Do not allow the ink to dry on the anilox roller, so as not to block the ink hole of the anilox roller, hindering the quantitative transfer of ink, resulting in poor printing. On the other hand, it is also necessary to pay attention to the printing process as much as possible to keep the printing plate wet by the ink, and to avoid the blockage of the text patterns on the printing plate after the ink dries.

Ink, from the perspective of the composition, is composed of water-based binders, pigments, fillers and additives. The ink ink produced by the ink factory has general performance as shown in the following table.

From the data in the table, it can be seen that the pH of the ink is between 9-9.5, which is weakly alkaline. In fact, the printability of PH value for ink is mainly related to the viscosity and dryness.

To sum up, the ink has the following properties: It belongs to a basic composite system with a PH value around 9; It is a Newtonian fluid system with low viscosity and good fluidity, and the viscosity of the machine is about 30 seconds (Paint No. 4); before the ink is dry Dissolved in water, the film is dried and converted into insoluble imprints; ink is a combination of infiltration, volatilization, and chemical conversion integrated drying; ink due to the absence of VOC, determines that this type of ink is environmentally friendly; ink adapted flexographic printing, It is mainly used for the printing of packaging and decorating products, such as kraft paper bags and corrugated cardboard boxes; it can also be used for gravure printing, such as candy paper, cigarette label, paper cup printing and so on.

2, ink color deployment - adjust the ink color

Color is the most intuitive evaluation indicator of printing quality. This indicator is determined by the color properties of the ink. When the ink printing is used for solid printing at the flexographic printing plate, the ink color distribution is one of the key factors for the success or failure of printing. The ink color distribution will be briefly discussed below.

2.1 Ink Matching Method The key to the success or failure of ink hue is to master the correct method. The color toning for ink can be based on the following methods:

2.1.1 First, parse the original and determine the primary color. Ink-toning is performed on the color sample of the original. In order to reduce the blindness of the color-matching, the color of the original must be analyzed first, and the color of the original is decomposed into the three primary colors of the color material, that is, which color materials are used for the color of the original. The primary colors are judged by subtractive mixing. At present, the analytical manuscript is mainly a combination of instrument colorimetry and human eye colorimetry. The instrument colorimetry is the use of spectrophotometer, densitometer, electronic color separation instrument to measure the optical density or tristimulus value of the original color. The quantified data representing the color is obtained; human eye colorimetry is a qualitative range of the three colors required to form the original color based on the original color in combination with experience. Because the color measurement of the instrument is more complicated, and the color is not a pure physical phenomenon after all, but a comprehensive reflection of physical and human visual physiology and psychology, that is, the final effect of printing color depends on the human visual psychology experience, so in the actual ink tone distribution Visual alignment is more straightforward and convenient, and instrument colorimetry is only used for standard analysis of colors.

2.1.2 Followed by the base ink tone, scraping color comparison. The ideal three-primary ink (base ink) can be formulated based on the results of the original color analysis. Accurately weigh the required amount of base ink (eg 10g), pick up each base ink with a dip knife and mix it evenly on the glass plate, visually measure the color of the ink and the original, and measure the edge adjustment. When the transferred ink color is similar to the original color , It is desirable to adjust the ink on the scratch paper for scratching. If the ink is printed at the end of the ink, it is mainly compared with the color of the original color and the color of the original. After repeated coloring, scraping, and color comparison, the detailed and meticulous work is performed. The color is exactly the same as the face of the original. Then, the amount of the base ink remaining is accurately weighed, and the remaining amount of the base ink is subtracted from the initial amount of the base ink that is called. This difference can be initially used as the amount of base ink required for preparing the original color, and finally, According to this amount, each base ink is weighed to perform blending, scraping, and color matching, and the ink color of the adjusted ink matches the original color.