Analysis of Influencing Factors on Film Quality of Precoat Film

In recent years, the coating of textbooks is basically using pre-coated films. As the use of time is not long, there are many problems, according to process practice shows that the quality of pre-coated film coating is mainly temperature and pressure. Three major factors of speed, so the correct handling of the relationship between the three, to ensure the quality of pre-film coating and the impact of the next process to the production of the key.

Paper-plastic coating is a comprehensive result of thermal compression and physical effects. Temperature, pressure, and speed are the three basic factors for achieving this comprehensive physical function. Correctly handling the relationship between these three is the key to process technology.

Temperature: The first key to the film. The adhesive used for the precoat is a hot melt adhesive. The temperature determines the melt state of the hot melt adhesive, determines the leveling performance of the hot melt adhesive, and determines the molecular orientation of the hot melt adhesive. The diffusion ability of three kinds of substances, such as BOPP film, printing ink layer, and paper substrate, also determines the crystallinity of the hot melt adhesive. Only by correctly controlling the temperature of the working area, can the solid heat of the pre-coating film on the film be achieved. The melted layer is completely melted into a viscous state, with proper fluidity to achieve wet adhesion to the surface of the printed matter, and at the same time, it is guaranteed to be cured immediately after compounding, so that the laminated film product has a smooth appearance, sufficient light, and a good degree of melting of the adhesive layer. No creases. And can peel off the ink.

The temperature control of the lamination process also influences and determines the change in the thermal resistance of the laminating film when it is heated, as well as its resistance to new thermal forces. Therefore, strict control of temperature is the primary key to precoat film coating. According to our practice. Temperature control is appropriate in the range of 80 to 100°C.

Pressure: Appropriate pressure should be used while properly controlling the lamination temperature, because the surface of the paper itself is not very smooth. Only under the effect of pressure, the sticky-flowing hot-melt adhesive will drive away the air on the surface of the printed material. Wet the surface of paper prints.

Generates colloidal molecules to the ink layer of paper prints, diffusion between paper molecules, misalignment, and good bonding to form a complete coverage of the entire surface of the print, so that the prints reach a bright, non-foggy, flat, crease-free adhesive layer , Adhesive effect is good, in the absence of wrinkles, the appropriate increase in pressure, in order to make full performance of the hot-melt adhesive thermoplastic curing machine, to ensure that the film products in the composite plus after the process, for a variety of Physical peeling, impact force and other effects have a strong resistance, (such as indentation, bronzing, hot melt adhesive, etc.) in order to achieve the internal structure and surface state of the composite print to achieve a perfect uniform speed.

Paper coating is a compound motion in motion. The speed of motion determines the time for the paper-plastic composite to stay on the heat-pressing work interface of the heat-compression bond, and also determines the temperature, pressure, and pressure of the laminator input. The actual value of the paper-plastic compound produced in the actual production process.

When the lamination temperature and pressure are fixed, the change of speed will cause the laminating effect to change accordingly, and due to the upper limit of temperature and the pressure supply, it will only change from the direction less than the setting value, and with the speed increasing, The drop is obvious, and the hot pressing force is declining, which deteriorates the compounding effect. The running speed is too fast, the bond is not firm, there is fog, too slow it is inefficient, and even foaming. Therefore, the composite running speed determines the time for the pre-coating film and the paper print to be bonded. According to our experience, the general speed control is appropriate for folio paper about 10-20 minutes a minute. (The speed of the electronic laminator is slower due to the smaller heat roller)

The actual values ​​of the three factors of temperature, pressure, and speed have a certain range. Due to the different equipment, this requires us to find the best value in practice in order to ensure the composite effect of the pre-coated film and to create favorable conditions for the next step of the spine cover to remain free from blisters.