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Characteristics of liquid soft plastic packaging film
The film material used for liquid soft plastic packaging film is mainly polyethylene (PE) co-extruded film, which must meet the requirements of packaging printing, processing, storage and transportation. From the appearance and performance of the film, it can be divided into three categories: soft milky white PE film, black and white co-extruded PE film, hard high temperature cooking PE film. Spot welding
The soft milky white PE film is mainly used for simple liquid packaging such as milk, soy sauce and vinegar. The co-extrusion blown film masterbatch is composed of LDPE, LLDPE and milky white material. The performance of the film is relatively poor, the sterilization temperature does not exceed 90 ° C, the shelf life is relatively short; generally used in manual or low-speed filling equipment. For example, low-grade milk packaging, the general shelf life of Zui three days, near sales.
The black and white film is mostly three layers, and the zui is mostly five layers. When the film is blown, the added intermediate layer is formed by cohesiveness of the barrier masterbatch. The black masterbatch of the heat-sealed inner layer functions to block light and block ultraviolet rays. Due to the existence of the intermediate barrier layer, it is composed of masterbatch such as E-VA and EVAL. The shelf life of the contents is longer and can be maintained for more than 30 days. However, there are some three-layer co-extruded black and white film on the market, and the middle layer is not It is composed of a barrier masterbatch, so such a black and white film is also in the category of *. Among the three types of films, the black and white film is not suitable for the printing operation. When the black and white film is formed, the amount of the slip agent and the brightener is large, so as to meet the requirement that the black and white film has a small friction coefficient on the high-speed automatic filling machine, and the added oily substance is extremely disadvantageous to the color printing process, and is greatly reduced. The adhesion properties of the ink layer. On most high-speed automatic filling machines, a sterilization system directly equipped with hot hydrogen peroxide is used for sterilization of the packaging film. In this case, attention must be paid to the effect of the sterilization conditions on the ink layer because some of the pigments in the ink have poor oxidation resistance. Tests have shown that the oxidation of hydrogen peroxide is significantly improved with the increase of temperature. Therefore, color printing manufacturers must clearly understand the post-processing conditions of customers when providing packaging materials.
The hard high-temperature cooking PE film is mainly used for dairy products such as yoghurt and soy milk. The contents are sterilized after filling, and the ultra-high temperature sterilization process is adopted. The hard co-extruded PE film is mainly composed of HDPE masterbatch, and part of LDPE and colored masterbatch are added. Therefore, the hard PE film has good high temperature resistance and can meet the requirements of ultra-high temperature sterilization. Due to the pressure difference during sterilization, it is easy to produce "expansion bag" phenomenon. Therefore, it is required that the hard PE film not only has good heat-sealing strength, but also the tensile strength of the film is good. Color printing manufacturers generally adopt "three meters throw high" or "People step on one foot" test effect.
Printing ink for liquid soft plastic packaging film
Liquid packaging films such as milk and beverages are usually printed by means of surface printing. Most of them are made of polyamide or modified into connecting materials. Such inks are developed early in China's gravure inks, and the production process is relatively mature and perfect. This type of ink is suitable for polyethylene and polypropylene film. The adhesion of the ink layer is good and the gloss is good. However, the polyamide ink has poor water resistance, is not resistant to grease, and is not resistant to freezing and other performance defects. This type of ink is printed in the summer at high temperatures, which tends to cause stickiness and softening. When printing at low temperatures in winter, it will freeze.
The liquid package is subjected to high temperature sterilization or freezing during the post-processing process of filling, circulation and storage. Therefore, the defects inherent in the polyamide-based surface-printing ink cannot meet the requirements of the liquid packaging, and the color printing manufacturer that produces the liquid package Non-polyamide-based surface-printing inks must be selected for different types of co-extruded PE films. Currently, liquid-coated inks are available in polyester and modified products, and are available in single-liquid and two-liquid reaction types. Ink.
Main products: pillow packaging machine; high-speed pillow automatic packaging machine: transparent film packaging machine: three-dimensional transparent film packaging machine: semi-automatic transparent film packaging machine: collection packaging machine
Liquid soft plastic packaging film meets the requirements of fresh drinks
In recent years, fresh milk, soy milk, and many fruit juice drinks and condiments in plastic film packaging have appeared in the market. Since milk, soy milk, beverages, etc. are fresh drinks, the requirements for hygiene and temperature are very strict. Therefore, there are special requirements for the printing of H bags, which makes the printing of milk and beverage packaging films different. Other printed technical features.