Liquid soft plastic packaging film meets the requirements of fresh drinks

In recent years, fresh milk, soy milk, and many fruit juice beverages and condiments packed in plastic films have appeared in the market. Since milk, soy milk, beverages, etc. are fresh food drinks, the requirements for hygiene and temperature are very strict. Therefore, there are special requirements for the printing of H-bags, which makes printing of milk and beverage packaging films different. Other printing technical features.

The 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 and hygiene. From the perspective of film appearance and performance, it can be divided into three categories: soft creamy white PE film, black and white co-extruded PE film, hard high temperature cooking PE film. Spot welding

The soft white PE film is mainly used for packaging of simple liquids such as milk, soy sauce and vinegar. The co-extrusion blown film masterbatch consists of LDPE, LLDPE and milky white material. The performance of the membrane, the barrier performance is relatively poor, sterilization temperature does not exceed 90 °C, the shelf life is relatively short; generally used in manual or low-speed filling equipment. Such as low-grade milk packaging, the general shelf life of up to three days, the nearest sale.

The black-and-white films are mostly three-layered, with a maximum of five layers. When the film is blown, the increased intermediate layer is a coextruded barrier masterbatch. The black masterbatch of the heat-sealing inner layer blocks light and blocks ultraviolet light. Due to the presence of an intermediate barrier layer and a masterbatch consisting of E-VA, eval, etc., 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 films on the market. The middle layer is not It is composed of a barrier masterbatch, so this black and white film is also in the first category. Among the three types of films, the black and white film is the most unfavorable to the printing operation. When the black and white film is formed into a film, the amount of the slip agent and the brightener contained therein is the largest, so as to meet the requirement that the black and white film has a small coefficient of friction on the high-speed automatic filling machine, and the added oily substance is extremely unfavorable to the color printing process and greatly reduces the Ink adhesion properties. In most high-speed automatic filling machines, a sterilization system with direct hot hydrogen peroxide is used to sterilize the packaging film. In this case, it is necessary to pay attention to the influence of the sterilization conditions on the ink layer because some of the pigments in the ink have poor oxidation resistance. Tests have shown that hydrogen peroxide oxidation increases significantly with increasing temperature. Therefore, color printing manufacturers must be clear about the customer's post-processing conditions when providing packaging materials.

The rigid high-temperature cooking PE film is mainly used for milk beverages such as yoghurt, soy milk and so on. When the contents are sterilized after filling, an ultra-high temperature sterilization process is used. The rigid co-extruded PE film uses HDPE masterbatch as the main component, adding some LDPE and colored masterbatch. Therefore, the rigid PE film has good high-temperature resistance and can meet the requirements of ultra-high temperature sterilization. Due to the pressure difference during sterilization, the "bulging bag" phenomenon is easy to occur. Therefore, it is required that the hard PE film not only has a good heat sealing strength, but also the tensile strength performance of the film is better, and color printing manufacturers generally use "three meters throw high" or "One foot on 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 polyamides or modified into binders. These inks were first developed in gravure printing inks in China, and the production process is relatively mature and complete. This type of ink is suitable for polyethylene, polypropylene film, ink layer adhesion fastness, good luster; but the polyamide type ink PuHH has poor water resistance, not resistant to grease, not resistant to freezing and other performance defects. Printing of this type of ink in high-temperature summers tends to produce stickiness and softening, and freeze-up occurs during low-temperature winter printing.

Liquid packaging in the post-processing of filling, distribution, storage, etc., must be sterilized by high temperature or frozen, so the inherent defects of the polyamide type table printing ink can not meet the requirements of liquid packaging, production of liquid packaging manufacturers of color printing Must be for different types of co-extruded PE film, non-polyamide type of printing ink, the most suitable liquid package ink in the market is polyester and modified products, single-liquid type and two-liquid reaction type Ink.