Why does the beer color when printed?

A certain packaging and decorating and printing factory uses yellow, golden red, green lotus and golden water-based inks, and 85 g/m square single-sided coated paper to print beer marks on a narrow-width flexographic printing press. In order to improve the abrasion resistance and water resistance of beer labels, the surface was UV-glazed.

The printed beer label is sent to the beer filling production line. After the wine label is affixed to the filled bottle, the wine label becomes dull, resulting in a discoloration phenomenon. .

In order to find the cause of the failure, the following tests were performed:

1. The water drops on the surface of the wine label, there is no decoloration;

2. Soaking the wine label in tap water did not result in discoloration;

3. Mark the paste on the back of the wine label and place it for a little while. The color on the label darkens and decoloration occurs.

4. The pH of the paste was tested with a pH meter and the pH was 13.

Analysis: The binder for water-based inks is an alkali-soluble binder that meets the requirements for water-based ink binders that can be dissolved in water during printing and become insoluble in water after drying. Alkaline binder is generally selected from acrylic resin, and an appropriate amount of amine compound is added. The soluble resin salt formed after chemical treatment is insoluble in water, but it is not alkali-resistant. Therefore, when the dried water-based ink ink film is penetrated from the back of the paper and the alkaline paste is applied, the resin dissolves and the printed color falls off.

Solution: Replace the neutral or weakly acidic paste paste label, remove the color failure is eliminated.

PP plastic, also known as polypropylene plastic, is another fine resin varieties, following the development of nylon, which is a semi-crystalline materials, the advantage is obvious, with excellent mechanical properties and heat resistance, with a high not hydrophilic sex, almost non-absorbent. The disadvantage is poor low temperature impact resistance, easier to aging. However, for comparison PE plastic having a higher melting point.

PE plastic is polyethylene plastic, its corrosion resistance and electrical insulation are very strong. Rigid hardness and strength are relatively high, and the same PP plastic, it also very small water absorption.

Polycarbonate (referred PC) is a polymer molecular chain containing a carbonate group, an ester group according to the structure can be divided into aliphatic, aromatic, aliphatic - aromatic and other types. Which due to the aliphatic and aliphatic - aromatic polycarbonate lower mechanical properties, thereby limiting its application in engineering terms. Currently, only the aromatic polycarbonate obtained industrial production. Due to the special nature of the polycarbonate structure, it has now become the top five fastest growing engineering plastics in general engineering plastics.

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