Raw material storage and pretreatment. The sole raw material is usually formulated into a composite material, and the three components A, B, and C with polyol, isocyanate and catalyst as the main components are supplied and sold. Their shelf life at room temperature and sealed conditions are 6 months, 3 months and 6 months, respectively. During the storage period, attention should be paid to preventing moisture and light, and it is strictly forbidden to expose to the sun and rain, and pay attention to ventilation. If the shelf life is exceeded, analysis and a small sample foaming test must be carried out before use to check whether it is invalid. The raw materials should be heated and melted before use.
If color matching is required, the color paste should be added to the A component, and it should be fully stirred before use to make it evenly dispersed; the catalyst component is usually added to the A component in the production plant, but because organic catalysts are easy to produce For hydrolysis, sometimes due to the different production conditions and environments in different places, the catalyst can be used as a component alone to facilitate adjustment. The catalyst should be added to the A component before use, and after stirring for at least 10~20min, then A The ingredients are added to the working tank of the foamer.
The correctness of the proportion of raw material components is the most critical condition to ensure product quality. Therefore, every day production must test and check the accuracy of the metering proportion of the foaming machine. When the newly added raw material or the metering pump error fluctuates greatly, special attention should be paid to the monitoring and inspection of the component proportioning metering. The measurement of raw materials by the foaming machine is mostly based on volume, and its volume is directly related to viscosity and even temperature. Therefore, in production, the pressure and temperature of each raw material must be strictly controlled within the predetermined range, otherwise, it will be serious. Affects the accuracy of component metering.
The sole mold is usually made of aluminum alloy and steel material. In recent years, the use of resin mold is very common. The pattern of the mold cavity must be clear, and special attention should be paid to the design of the deep concave-convex pattern when designing the mold, which must be conducive to the discharge of air bubbles, avoid acute-angled concave-convex patterns, and should be changed to arc-shaped transitions if necessary.
The direction parallel to the bending direction should preferably be around 45°. In the past, some people thought that the finished sole should not be too thick, generally 6~8mm, usually no more than 12mm; but now the pouring of soles with a thickness greater than 12mm has been fully mastered.
When adding inserts such as wood cores, the wood core must be dry. The mold temperature should be controlled at 45~55℃.
According to the shape and density requirements of the sole, the injection amount of the foaming material should be adjusted appropriately. When pouring high-heeled soles, the heel part should be properly raised when installing the mold. When pouring, pour part of the material in the front part and then pour the heel (so that the foam center is not concentrated at one point), and the injection amount should be 40%~70%; when pouring flat shoes, the sole part of the mold should be slightly lifted up to should. To adjust the appropriate angle of the mold on the production line, the mold inclination angle must be adjusted according to the shape of the sole to avoid defects such as voids and air bubbles on the sole surface.
The molding time of the polyurethane sole is generally 5~7min. At this time, the performance of the polyurethane sole has not yet reached the optimum level, and it is not allowed to use too much force when demoulding. The semi-finished product after demoulding should be placed at room temperature for 1 day, and the release agent adhering to the surface of the product should be cleaned within 24 hours to facilitate the processing after color spraying.
