The seven sentences of solvent-free compounding, recommended by the ten-year soft-pack teacher!
Adhesive, and ink, matching test should be kept in mind; In winter, the room temperature is low, do n’t forget to preheat the mixed glue; A, B glue, mixing ratio, wait until the temperature is stable before measuring; In the plastic bucket, the humidity value, too large or too small, is not good; The measurement gap should be accurate and the temperature of the steel roller should be reasonable; The winding temperature is well controlled, and the sticking of the winding core is eliminated; Keep in mind the above points, solvent-free compounding can be done! 1. Adhesives and inks, the matching test should be kept in mind Prior to formal production, targeted compatibility tests should be conducted on inks containing pigment components (such as transparent yellow, peach, etc.) and solvent-free adhesives. We know that the solvent-free adhesive has a small molecular weight, and its surface has a strong penetration ability. The miscibility of the ink is mainly manifested in the low molecular weight curing stage. It is generally judged whether the ink will be miscible with the solvent-free adhesive The phenomenon needs to be judged after the solvent-free composite product has matured for 4 hours. In addition, we can also simulate the actual compounding process to determine whether the ink and solvent-free adhesive will be miscible. The specific method is: use A / B mixed adhesive to compact the printed film and the light film (or aluminum film) Laminating, and then put the laminated films into the oven for a period of time, and observe whether the edges of the printed graphics appear unclear. If they are not clear, it indicates that miscibility has occurred. 2. In winter, the room temperature is low, do n’t forget to preheat the mixed glue In the case of low room temperature in winter, the A / B mixed glue should be put into the curing room for preheating in advance. The preheating temperature is generally around 45 ℃, so that when the A / B mixed glue is poured into the rubber barrel, it will not Due to the excessive temperature difference, the temperature fluctuation of the A / B mixed glue in the rubber drum will occur. However, the A / B mixed glue can not be placed in the curing room for a long time, otherwise it may cause the defoamer component to fail. 3. A and B glue, mixing ratio, wait until the temperature is stable before measuring The metering pump measures the mixing ratio of the adhesive by volume. When the temperature changes, the density of the glue will also change. Because the density of the two components of A and B is different, the density of the two varies with the temperature. The proportion of change is also different, which will lead to a certain discrepancy between the A and B rubber compounding ratio measured at low temperature and the A and B rubber compounding ratio measured when the temperature rises to normal temperature. Therefore, before starting each working group, the mixing ratio of A and B glues should be measured after the temperature of the glue mixer is stabilized. 4. The humidity value in the plastic bucket is too big or too small to be good The main component of A glue is -NCO, which is prone to crosslinking reaction with moisture in the air. Generally, if there is a skinning phenomenon on the surface of the adhesive in the A barrel, it indicates that the crosslinking reaction has occurred on the surface of A glue. Moreover, when the humidity of the air is high, the moisture content of the air in the rubber bucket will also be high, so it is necessary to use a desiccant to filter and dry the air in the rubber bucket. If the desiccant changes color when it absorbs moisture, it means that its moisture absorption efficiency has deteriorated. At this time, it should be dried again before use. Some flexible packaging companies use the method of filling N2 in A plastic drum to eliminate the air in the plastic drum, and the effect is also better. Fifth, the measurement gap must be accurate The metering gap will change at different metering roller temperatures, which will result in inaccurate metering, and the greater the temperature difference, the greater the metering gap deviation, and even the metering roller surface will be damaged. 6. The temperature of the steel roller should be reasonable The temperature of the coating steel roller and the temperature of the metering roller are controlled separately and can be set according to the viscosity-temperature characteristics of the adhesive. Generally, the temperature of the coating steel roller is about 5 ° C higher than the temperature of the metering roller, which can further reduce the adhesive Viscosity, improve the leveling of the adhesive, so as to get a better composite appearance. In addition, it is necessary to compensate for the heat removed from the roll surface due to the low temperature of the coated substrate to maintain the actual temperature of the coated steel roll surface. Seventh, the winding temperature is well controlled After rewinding the composite film, it is required to keep a certain residual temperature on the surface to maintain the consistency of the internal and external curing effects. Because the winding diameter of the solvent-free composite product is large and the curing temperature (35-40 ℃) is lower than that of the dry-type composite, external heat transfer alone cannot guarantee the curing effect in the middle of the composite film roll. Factors and control methods that affect the winding temperature of the surface of the composite film roll: ①ambient temperature, solvent-free composite operating environment should be constant temperature and humidity; ② substrate film roll temperature, because the winter room temperature is lower, the substrate film roll temperature is also lower, In particular, the substrate film roll just taken out from the warehouse and put into the workshop is often cold. At this time, it is best to put the substrate film roll in the workshop to warm it up to increase its temperature before use; ③The substrate is preheated In the environment with low room temperature in winter, the second unwinding preheating roller device of the solvent-free composite equipment should be used to preheat the substrate to avoid the winding temperature of the surface of the composite film roll being too low; ④The composite temperature will It directly affects the winding temperature of the surface of the composite film roll, and it should be properly adjusted during operation. In addition, for anti-static PE materials, due to the anti-static agent's stickiness, the composite roller needs to be used in actual production. The temperature is set lower. 8. The sticky edge of the core is eliminated There are two main factors that lead to the phenomenon of core edge sticking: one is the deviation of the composite opposite edge, and the other is the large amount of coating. Because the solvent-free composite equipment runs at low speed (<50m / min), the coating amount is generally about 0.2 ～ 0.3g / m2 higher than the normal machine speed. Therefore, when the solvent-free composite equipment runs at low speed, the speed of the metering roller should be reduced . In addition, when the coating pressure roller is not pressed, and the transfer rubber roller (between the metering roller and the coating steel roller) is pressed, a large amount of glue will accumulate on the surface of the coating steel roller, so that when the coating pressure roller presses When going down, the excess glue will spread to both sides of the coating steel roller, which will cause the core to stick to the edge. Therefore, when the coating pressure roller is not pressed, try not to press the transfer rubber roller in advance to avoid coating steel. Roller surface area glue.
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