Impact of Slipperiness on Film Production, Printing, Lamination, and Bag Making
Influence on Film Winding Tension and Quality: The pressure and distance between layers of laminated film after winding are closely related to the uniformity of individual substrates, the design of printed patterns, and the thickness of ink layers. A thicker ink layer results in greater hardness after winding, leading to increased pressure and reduced distance between layers. In regions with thicker ink layers, the probability and quantity of migration of slip agents from one film to another are higher. Consequently, the friction coefficient of the heat-sealed surface in areas with thicker ink layers is noticeably greater than in areas with thinner or no ink layers.
Additionally, if the friction coefficient of the composite film is too low, the frictional force between the inner and outer layers of the film during winding is minimal. As the roll diameter increases, the frictional force may not support the neat winding of the film, leading to telescoping, hindering the transition to the next production process and requiring rewinding. In some cases, improper winding can result in roll disintegration, leading to material waste. Conversely, if the friction coefficient is too high during winding, it may cause quality issues such as severe wrinkling and film breakage.
Impact on Automatic Packaging and Bag-Making Processes: The friction coefficient is a crucial indicator for the use of composite films, with different packaging materials having varying requirements. In the context of automatic packaging and bag-making machines, as equipment continues to advance and production speeds increase, the demand for a precise and higher friction coefficient of composite films becomes more stringent. Typically, the film surface friction coefficient for automatic packaging films is required to be between 0.20 and 0.30 (referring to BOPA film), with even smaller requirements for high-speed coding (bag-making) operations exceeding 250 items/minute. For specialized processes or targeted products, caution should be exercised when considering extremely low friction coefficients. Controlling the friction coefficient between the film and metal within a certain range is essential, taking into account the film's moisture absorption during use. Materials like nylon film and glassine paper exhibit higher friction coefficients after moisture absorption. If the friction coefficient is too low, issues such as unstable material feeding, slipping during traction, misalignment in electronic eye tracking, bleeding in bag-making cutting, or inconsistent finished product specifications may arise, leading to increased waste. Conversely, a too-high friction coefficient results in increased frictional force between the film and the machine, making material dragging difficult and causing feeding difficulties, material stretching or tearing, ultimately disrupting the production process.