Effect of pre-film removal technology on the adaptability of rubber cover

In recent years, the coating of textbooks is basically using pre-coated films. Since we have not used a long time and there are many problems, according to our process practice, it is shown that the quality of precoated 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.

We know that the paper-plastic coating will be the combined result of thermal compression and physical effects. Temperature, pressure, and speed are the three basic factors for achieving this comprehensive physical effect. Correctly handling the relationship between these three is the key to the technology of process operations.
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 material and at the same time to ensure immediate curing after compounding. The laminated product has a smooth appearance, enough light, good melting of the adhesive layer, and no crease. 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 100C.

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 , Adhesion effect is good, in the case of no wrinkling, 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. It has strong resistance to various physical peeling and impact forces. (such as indentation, hot stamping, hot melt adhesive, etc.) to achieve a uniform speed of the internal structure and the surface state of the composite print: the paper cover film is a compound motion in motion. The speed of the movement determines the time for the paper-plastic composite to stay on the hot-pressing work interface of the thermal-compression bond, as well as the temperature and pressure input by the laminating machine, as well as the cooperation between the paper and the plastic during the actual production process. Actual value. When the film temperature and pressure are fixed.

The change of speed will cause the film coating effect to change accordingly, and due to the upper limit of temperature and pressure supply, it will only change from the direction less than the set value, and with the speed increase, the drop will be obvious, and the hot pressing force will decline. Deteriorating the compounding effect. Running too fast. Bonding is not strong. There will be fog, too slow it is inefficient. Even blistering.

So composite speed. Determine the time for the precoating film and paper print to achieve bonding. 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 smaller due to the hot roller. The speed should be slower.)

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 spine cover of the next process to keep the shell spine free of bubbles.

The compounding of the pre-coated film and how to create favorable conditions for the next process (including indentation, bronzing, binding, etc.) is also one of the important factors that we should consider when using the pre-coating film to perform the laminating operation process.

Pre-coated film and paper print composite. The lower limit is 80C and the upper limit is 100C. Intuitively, after the composite body is separated from the hot platen roller, it has high brightness, no fogging, good flatness, and no blistering as a benchmark. In such a temperature range, the hot melt adhesive can fully absorb heat from the outside to the inside. The effect of the modification of various raw materials in the gel can be fully utilized, and the entire adhesive layer is completely melted. The result is a true, firm bond, rather than a superficial, shallow, off-shell, blistering phenomenon that must not be bent or reheated.

When the lower limit temperature is slightly down, the brightness of the composite product will decrease. When the upper limit temperature rises slightly, uneven and differently shaped bubbles will be burned on the surface of the film. (This phenomenon is particularly evident in electronic laminating machines.) It is just right to grasp the critical working area of ​​coating temperature. Not only the composite effect is good, but also the hot-melt colloid is close to the cross-linking reaction hotspot, and the colloidal solidification is hardened, so that when it is heated again, it will not be easily softened. The correct temperature control method for the laminating operation is to grasp this finely. The coating temperature is very close to the crosslinking reaction temperature.

Recently, we have used pre-coated films for post-gluing, binding, and binding, and found that most of the books that have undergone recoiling after splitting have been subjected to bookbinding, blistering, and blistering. This phenomenon does not occur when the membrane is cooled by water immediately after leaving the heat source and it is automatically divided. (Our equipment is equipped with a water-cooling system, an automatic partitioning system, and a winding system for optional use.) The curing time of the hot-melt adhesive for the film is about 10 to 15 seconds, and the time required for natural cooling in the production environment at room temperature is greater than this. Standard time, especially if semi-finished products are stacked before winding up. Accumulation of temperature between each other is difficult to disperse, allowing natural cooling to solidify

Prolonged, usually slow cooling naturally. Will make hot melt gradually crystal. The generation of crystals increases the sensitivity of the colloids to the temperature, may cause the softening of the hot melts again, and weakens the heat resistance of the high-temperature laminating operation to approximate the cross-linking reaction. Therefore, we use water-cooling and real-time automatic Dividing to prevent heat from accumulating, creating a low-temperature quenching zone immediately after the film product is detached from the heat source. Let it cool down quickly. Makes the viscosity of the hot melt in the molten state increase rapidly. Chain link is too late to exercise. The crystals are difficult to form, which can make the coated products reheat without remarkably melting and softening. It will not cause spine shelling or blistering when the glue binding is done to ensure that it is warm again. In order to ensure good binding conditions for the perfect binding, the quality of binding and laminating products is more assured.