Analysis of Quality Control Points for Color Aluminum Foil Printing

In the mid-1980s, foreign drugs that were packaged using advanced technologies began to flood into China, and the domestic pharmaceutical market was impacted. At that time, most domestic medicine tablets still used old-style glass bottles and other packaging forms. China's pharmaceutical industry opened the prelude to the replacement of pharmaceutical packaging of various materials, including the use of aluminum foil with superior performance in all aspects. product. We have successively introduced foreign aluminum foil printing and coating equipment production lines to reach the scale production capacity of blister packaging. In the early stage of production, the raw materials for aluminum foil in China were all imported. The annual output was about 400 tons, and most of them were “foil” printed on the surface of aluminum foil without a text pattern. A few products were printed on one side with aluminum foil.

In recent years, the application scope of aluminum foil packaging has been expanding. In addition to pharmaceutical packaging, food packaging, health care product packaging, etc. have been applied, prompting the continuous improvement of China's aluminum foil printing technology, and now can achieve both sides of aluminum foil can be printed on both sides. Not only can print a color of the product, but also can be printed into a variety of multi-color colorful text patterns, aluminum foil surface coated with imitation gold foil and other colors are displayed in front of consumers, this packaging form makes people feel noble Gorgeous, put it down, played a good role in propaganda and protection of products.

Gravure printing color foil

The aluminum foil printing is to print the text pattern through the concave surface of the printing plate roller. First, the printing plate roller is processed into a printing plate graphic by external processing. The graphic part is eroded into ink holes or pits on the surface of the copper layer of the roller. The non-graphic part is the outer copper surface of the roller itself. The plate cylinder rotates in the ink tank, and each ink hole is filled with thin ink. When the roller rotates out of the surface ink tank, the excess ink on the upper surface is the blade installed on the surface of the plate cylinder. Scraping, when the plate roller and the substrate contact with the aluminum foil, the surface of the elastic rubber embossing roller presses the surface of the aluminum foil to the plate cylinder so that the ink in the ink hole is transferred to the surface of the aluminum foil. At this point, the aluminum foil printing is completed. jobs. Since aluminum foil material is different from paper materials and plastics, the key to its printability is to master ink characteristics, ink viscosity, and ink drying degree so as to print a product that meets quality standards and achieves user satisfaction.

Ink and foil printing applicability

Printing inks for aluminum foils are mainly divided into two categories: one is a polyamide ink, which has good adhesion, dispersibility, gloss, abrasion resistance, and solvent release properties for the printing of aluminum foils. Because of its softness, it is mostly used for the printing of plastic film. When applied to the printing of aluminum foil as a substrate, the excellent performance of this ink can be expressed, and its heat resistance can also meet the requirements of aluminum foil printing. The other type is a complex aluminum foil ink based on a copolymer of vinyl chloride and vinyl acetate copolymer, which is mainly composed of grease/acrylic resin. It is characterized by bright color, high concentration, particularly strong adhesion to aluminum foil, and good transparency. , In the choice of pigment, do not use toxic components such as heavy metals, widely used in medicine, food, health products packaging.

Adjustment of the viscosity change of aluminum foil printing ink

The inks suitable for aluminum foil printing have been selected, but the viscosity of each ink is different. The inks used do not precipitate during the storage process. Generally, the viscosity is relatively large. When printing, the ink should be diluted to achieve the viscosity and the viscosity used. Liquidity, which also depends on the structure of the device and the printing speed. The viscosity of the ink is generally measured with a No. 4 viscosity cup, and the printing speed of the machine is between 30 and 70 m/min. Viscosity is adjusted between 25-30 seconds. In the application of larger viscosity inks, the use of a large amount of diluent should be dissolved uniformly, so that the diluent is evenly distributed throughout the ink, due to the indoor temperature and humidity have an impact on the ink concentration, it is best to use the ink concentration detector to determine The amount of solvent is added, and the ink concentration is measured at regular intervals depending on changes in temperature and humidity and printing speed. When gravure is used to print aluminum foil, if the ink concentration is too low, the printed text pattern will not be bright and the web will have a “sticking” phenomenon. Too much ink concentration will cause cracks in the pattern, which will not only waste ink. , And easy to cause the print surface is not smooth, not beautiful.

The degree of ink drying in printing

The drying of the ink in the aluminum foil gravure printing process is accomplished by the volatilization of the solvent, and the ink is dried by the action of the heater and blowing hot air. The degree of drying of the ink should be matched with the printing speed and the drying temperature, and these two basic factors can be adjusted at any time in combination with the indoor temperature and humidity. When the printing speed and drying temperature are constant, the indoor temperature is too low, the ink will dry too slowly on the surface of the aluminum foil, and a quick-drying solvent or a quick-drying diluent may be added to the ink, whereas the ink may be dried too quickly, and an appropriate amount may be added to the ink. Slowly dry the diluent to suit the changes in ambient temperature and humidity during the printing process.

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