Application and advantages of flexible plate coating technology in dry compound machine
In the soft packaging industry, composite is a crucial process. In recent years, with the increasingly mature solvent composite process, soft packaging composite process has gradually developed into a situation where dry composite and solvent free composite have complementary advantages and mutual coexistence. However, the dry composite process has been restricted by production speed, production cost, production cycle and other factors, and its development is relatively slow. In recent years, flexible plate coating technology has gradually emerged, as a new dry method composite coating technology, has solved the problem of high speed composite apparent quality, and can adapt to the state of high concentration glue coating, greatly reduce the use of solvent, attracted the focus of #soft packaging industry. I. working principle of flexible plate glue coating The flexible version of adhesive coating is unique in structure, similar to the five-roll transfer coating method without solvent composite, but it is different. Due to the difference in glue characteristics, flexible plate coating generally adopts the "four-roll transfer" glue coating method, the rubber roller and steel roller alternating distribution, so some equipment manufacturers named "semi-flexible glue coating", in fact, the structure principle is the same, The key is the manufacturing accuracy and control accuracy of each roller. Based on the in-depth understanding of the composite process, the application level of the equipment will be different. As shown in the right figure, the two rollers immersed in the glue groove are the cots and the metering roller in turn. There is a certain speed ratio. Convenient and rapid change of sheet), and then from the glue roller to the coating on the top of the steel pressure roller on the base material, to achieve the glue transfer coating. image.png In the flexible plate coating system, the precise control of the amount of glue is the core, but it is different from the traditional way of glue coating, which is not simply determined by the concentration of working fluid and the number of wire rollers, but is jointly influenced by four key factors: First, the gap between the cots and the metering roller can be adjusted. By adjusting this gap, the amount of glue can be changed. Secondly, the change of working fluid concentration will directly lead to the change of gluing volume; Third, the measurement roller with different lines can also achieve the adjustment of glue volume, but usually equipment manufacturers do not recommend frequent replacement of network roller; Fourth, the speed difference between the glue roller and the measurement roller will also make the amount of glue change. In particular, the clearance and speed difference between the measuring roller and the coating roller greatly improves the surface coating state of the glue, even if the glue concentration is high, it can still achieve a more uniform and flat coating state. Ii. Advantages of flexible plate coating technology (1) use of ultra-high concentration working fluid Under the traditional uniform coating method of regular roller, the general working fluid concentration is 30% ~ 35%. Flexible plate coating technology, with its unique mechanical structure and control system, can still obtain a better surface coating state under the condition of ultra-high working fluid concentration (40%~55%). Taking the common 75% solid adhesive as an example, the working fluid concentration is 30% ~ 35% in the normal coating mode, while the working fluid concentration can reach 40%~50% or higher when the flexible coating method is used. This means that the use of flexible glue can greatly reduce the use of solvents. Through calculation, the traditional roller coating method was used, the main agent: solid content agent: solvent = 20:4:30, the concentration was about 33.3%, while the flexible plate coating method was used. Each group of glue saves solvent consumption 30-12=18kg(solvent), that is, it is equivalent to 0.75kg per kilogram of glue. Estimated at 7,000 yuan per ton, 750kg x 7 yuan = 5250 yuan. It can be seen that the use of flexible coating technology can significantly reduce the cost of solvent use. However, with the increase of the concentration of working fluid, the speed of glue viscosity is accelerated, which will affect the surface coating state of glue to some extent. Therefore, the viscosity change must be strictly controlled when the machine produces 50% of the ultra-high liquid concentration. At present, although there is a viscosity control instrument to control the viscosity change caused by solvent volatiles, it is difficult to completely control the viscosity change generated by glue a and b components. In the case of manual glue distribution, this viscosity change is almost uncontrollable, so it is recommended that the manufacturer use automatic glue matching machine, in order to achieve 15~20min to match the glue once, so as to effectively control the viscosity. (2) greatly reduce the amount of glue In the traditional ripping roller drying compound production, people often fall into a mistake, that is, by increasing the amount of glue to improve the apparent state of coating, to meet the performance requirements of composite fastness and other properties, but ignore how to improve the surface coating state of adhesive substrate. In fact, the surface flatness of the glue solution, the uniformity of the coating surface is the key factor that determines the quality of the product. The size of the glue should be determined by the surface coating state of the glue. Compared with the straight coating method of corrugated roller, flexographic coating method can greatly improve the surface coating state of glue, which creates favorable conditions for reducing the amount of glue. For example, in some actual production cases, the same material structure and printing film meet the required composite performance index. When the mesh roller was used, the amount of glue on the roller was 4.2~4.5g/m2, while after using the flexible version, the amount of glue on the composite pure aluminum foil can be reduced to 3 ~ 3.5g. When using the roller, the amount of glue on the roller is 3~3.5g/m2, and after applying the flexible version, the amount of glue on the roller can be reduced to about 2.5g, and the amount of coating can be reduced by 15% ~ 25%. The fact of mass production shows that the dry composite process using flexible plate coating method can achieve a level of glue cost and solvent free compound in some product fields, and the composite quality and production efficiency are higher. However, due to the differences in the structural performance of different products, different operators' proficiency in operation are also different. In reducing the amount of glue, small batch tests should be carried out first to ensure that the quality of products is not affected. (3) improve production efficiency The dry composite machine of flexible plate coating method is usually high-grade dry compound machine, the overall performance of equipment is excellent, and its production efficiency is significantly improved than that of general dry machine. Some equipment can run at a speed of up to 300m/min, and can achieve aluminum foil glue. In terms of order replacement, since there is no need to replace the net roller like the traditional roller coating to adjust the amount of glue, it is necessary to easily adjust the relevant parameters to change the amount of glue. At the same time, the upper gluing roller adopts sleeve design, and the replacement of sleeve roller with different specifications and sizes can be completed within 5min, which saves at least 30min the replacement time of different orders, greatly improving the flexibility and efficiency of production. (4) to reduce the comprehensive cost Combined with the reduction of solvent cost caused by the use of ultra-high concentration working fluid and the reduction of glue value saved by the reduction of glue, flexible plate coating method has a significant reduction in composite cost compared with the coating method of corrugated roll, which can generally reach 30% ~ 50%. Taking 75% solid adhesive as an example, it can be seen from the calculation that flexible plate coating can save a lot of costs in terms of glue use cost. In addition, due to the flexible version of glue coating technology, it can improve the production efficiency, reduce the time of order replacement, and indirectly reduce the production cost and reduce the energy consumption loss per unit capacity. Iii. Application status and development trend of flexible plate coating technology At present, the domestic equipment factory has the strength to introduce the use of flexible plate coating technology dry recovery machine, more and more soft packaging manufacturers began to pay attention to and purchase such equipment. With the continuous development and improvement of technology, #flexible plate #coating technology is expected to be further optimized in the future. On the one hand, in the aspect of glue research and development, it may develop glue that is more suitable for flexible version glue coating technology, so as to better adapt to the requirements of ultra-high concentration use and lower glue volume, and further improve product quality. On the other hand, equipment manufacturers will continue to improve the performance and stability of equipment, improve the degree of automation, reduce the cost of equipment, and make flexible plate coating technology more widely used in the soft packaging industry. Flexible edition adhesive coating technology has brought new changes to the upper adhesive technology of dry machine with its obvious advantages in reducing production cost, improving product quality and production efficiency. In today's increasingly fierce market competition, this technology will become one of the important means for soft packaging manufacturers to improve their competitiveness, promote the development of the whole soft packaging industry to be more efficient, more environmentally friendly and better quality, and bring new vitality to the complex soft #packaging.
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