The vulcanization time of insole silicone is usually determined according to the product thickness, vulcanization temperature and process requirements, generally ranging from tens of seconds to several hours, and needs to be optimized in combination with experimental and production conditions. The following are key influencing factors and common parameter ranges:
Relationship between vulcanization temperature and time
Increasing the vulcanization temperature will accelerate the cross-linking reaction rate of silicone molecules and shorten the vulcanization time. For example, when silicone is vulcanized at 180-200°C, the time may be 4-12 hours; while liquid silicone rubber vulcanizes very quickly at high temperatures (such as above 200°C), and can be completed in 20-30 seconds. However, excessively high temperatures may cause silicone to coke or degrade in performance, and a balance between temperature and time is required.
The effect of product thickness on vulcanization time
Thick products (such as insoles) require longer vulcanization time to ensure complete internal vulcanization. For example, silicone pads with a thickness of 3mm, 5mm, and 8mm take 3 hours to naturally vulcanize in air at 23°C, while thick products in industrial production may take several hours or even longer.
Choice of vulcanization process
Silicone insoles are usually molded or injected, and the vulcanization time needs to be adjusted according to the process. For example, liquid silicone rubber vulcanizes very quickly during injection molding, while ordinary silicone may take longer. In addition, a two-stage vulcanization process (such as 170-180°C for the first stage and 200-230°C for the second stage) can further improve performance, but the total vulcanization time needs to be extended.
Experimental optimization and production practice
The actual vulcanization time needs to be determined through experiments, taking into account factors such as silicone formula, vulcanizer type, and mold design. For example, the vulcanization time of foamed silicone insoles may be adjusted according to indicators such as density and foaming ratio, ranging from 9 minutes for the first stage vulcanization and 20-40 minutes for the second stage vulcanization.