- Polyethylene film
The ink adhesion of polyethylene film is poor and needs to be improved by corona treatment. During corona treatment, ensure that the critical surface tension of the film reaches 40-44mN/m. Commonly used polyamide ink for printing. Due to the poor heat and oil resistance of polyamide ink, acrylic or chlorinated polyolefin inks can be selected for film printing inks with heat resistance requirements. For film packaging of fats and monosodium glutamate, vinyl chloride vinyl acetate copolymer ink can be selected.
Low density polyethylene film will soften after being heated, making it easy to stretch and deform, and it is difficult to color and adjust. Therefore, when drying, the surface heating temperature of the film should not be too high, generally not exceeding 50 ℃. If hot air drying is used, adjust the air volume to prevent the film from vibrating. To prevent ink adhesion, the film should be fully cooled before winding, so that the temperature of the film can be reduced to close to the heat sealing properties of the room type low-density polyethylene film. The tensile strength and puncture resistance are better than low-density polyethylene, and the printing adaptability is similar to low-density polyethylene film. Generally, positive printing is used.
The heat resistance and mechanical strength of high-density polyethylene film are stronger than those of low-density polyethylene film, with a lower tensile rate. The film thickness is below 0.03mm, and its transparency is poor. It is also printed on the front side of the film. - Polypropylene film
The transparency, heat resistance, and printing operability of polypropylene film are superior to those of polyethylene film. Similarly, its ink adhesion is poor and requires corona treatment before printing to improve it. It is advisable to control the critical surface tension between 40-44mN/m during corona treatment. Commonly used polyamide inks and chlorinated polyolefin inks.
