Corrugated box printing water-based ink points and failure analysis (on)

With the development of economy, the packaging industry has entered a period of rapid development, and water-based inks have been widely used in various types of carton packaging and printing mainly for corrugated cartons because of their unique environmental advantages and excellent performance.

Water-based ink properties and characteristics

1. Basic properties of water-based ink

(1) Color

Color is the most intuitive performance of water-based inks, which can be reflected by hue and tinting power.

Water-based inks mainly use standard ink samples or standard print samples to control the color of inks. According to the requirements of the printing factory, the inks of the same series can be mutually deployed to obtain the desired hue.

The general water-based ink color is certain, but when the printing conditions (such as printing speed, the number of anilox roller, water-based ink viscosity, paper color, etc.) change, its printing effect on the substrate will also change Therefore, in the printing process, the ink should be used under the same printing conditions as much as possible to ensure the stability and consistency of the print color.

(2) Viscosity

The viscosity of water-based inks is generally expressed in terms of flow time, that is, the time during which a certain amount of ink flows freely through the viscosity cup under the action of its own gravity. Viscosity is the main indicator of water-based ink viscosity directly affects the quality of printed matter.

The low viscosity of the water-based ink will cause the printing pattern to become lighter in color, imprecisely printed, enlarged dots and uneven ink transfer. The viscosity of water-based ink is low. On-site treatment method: Generally, the method of blending with the original ink may be used to adjust, or an appropriate amount of thickener may be added to increase the viscosity of the ink.

The high viscosity of the water-based ink will affect the ink transferability of the anilox roll, resulting in the disadvantages of uneven ink, slow drying of the ink, stencil, stickiness, and poor leveling. High viscosity of water-based inks In-situ treatment methods: Generally, water (or a mixture of water and ethanol) may be diluted, or an appropriate amount of pH adjuster may be added to increase the pH to reduce the viscosity of the aqueous ink.

(3) Dryness

In addition to the performance of the ink itself, the drying speed of the ink is related to the printing speed, the drying ability of the drying equipment, and the absorbability of the printing material to the ink.

Corrugated board printing is generally an osmotic absorption type of natural drying method, water-based ink drying too fast, prone to blockage, imprinting is not clear and so on; drying too slow will cause dirt, adhesion and other issues.

Therefore, the drying performance of the ink itself must be matched with the printing speed, paper properties, printing environment and other conditions, and the drying property of the water-based ink should be adjusted according to actual printing requirements.

(4) pH

PH value reflects the pH of water-based inks. At present, the binders used in water-based inks are mainly alkali-soluble acrylic resins, so pH control is very important. Usually the PH value should be controlled at 8.0-9.5. At this time, the printing performance of the water-based ink is relatively best, and the quality of the print is also the most stable.

(5) Other properties

After corrugated cartons are printed, they are often subjected to a variety of post-processing operations, such as light and film coating, which imposes special requirements on the performance of water-based inks, including abrasion resistance, slip resistance, and various patience (“water resistance, heat resistance, and resistance”). Freeze, acid, alkali, and organic solvents, etc.) Ink manufacturers will design inks according to specific recipes.

2. Basic features of water-based ink

Water-based ink mainly adopts alkali-soluble resin system and has certain alkalinity. At present, it is mainly applied to the printing of paper substrates.

(1) It can be diluted and cleaned directly with water. It has low odor and is easy to use. It has the advantages of environmental protection and safety.

(2) The printability of various types of paper is good, and generally there is no problem of poor adhesion.

(3) Alkaline, PH value is generally in the range of 8-10.

(4) The law of viscosity change is complex. Besides conventional factors, it is also easily affected by pH value, a small amount of volatile components and certain additives.

(5) Easily foaming, reduce foam generation during production and printing.

(6) The double drying mechanism of permeation absorption and evaporation drying, and the control of the drying speed of each color ink during multi-color overprinting.

(to be continued)