Principle of secondary vulcanization of silicone sealing ring

As an important sealing component, rubber sealing rings are widely used in various fields such as machinery, electronics, chemical, medical, and food. To ensure optimal sealing performance, the silicone sealing ring needs to undergo secondary vulcanization treatment during the production process. This article will delve into the principle of secondary vulcanization of silicone sealing rings. Silicone sealing rings may undergo a Post Cure process during production, which is a heat treatment process used to improve the physical properties and chemical stability of silicone products.Principle of secondary vulcanization:
Eliminating internal stress: During the initial vulcanization process, due to uneven factors such as vulcanization speed, vulcanization temperature, and pressure, internal stress may occur inside the silicone sealing ring. Secondary vulcanization can help release these internal stresses and reduce the risk of deformation and cracking of the product during use.Improving the degree of vulcanization: The initial vulcanization may not fully achieve the optimal vulcanization state of the silicone gel. Secondary vulcanization involves further heat treatment to supplement the areas that have not been fully vulcanized, thereby improving the overall performance of the product.Improving physical properties: Secondary vulcanization can improve the hardness, tensile strength, rebound and other physical properties of silicone sealing rings, making them more stable and durable.
Stable chemical performance: Secondary vulcanization helps to maintain the long-term stability of silicone sealing rings, reducing performance degradation caused by environmental factors such as temperature, humidity, chemical corrosion, etc.Secondary vulcanization steps:
Preparation: Place the silicone sealing ring in a suitable heat treatment equipment, such as an oven or vulcanization tank.
Set temperature: Set the temperature for secondary vulcanization based on the type and performance requirements of the silicone gel. Usually, this temperature will be slightly higher than the initial vulcanization temperature.
Heating: Heat the device to the set temperature and maintain it for a period of time to ensure that the silicone sealing ring is fully heated.
Insulation: Keep at a set temperature for a period of time, usually a few hours, to ensure sufficient vulcanization reaction.
Cooling: After completing vulcanization, gradually reduce the temperature to slowly cool the silicone sealing ring to room temperature.
Removal: Remove the silicone sealing ring from the heat treatment equipment and prepare for subsequent inspection and packaging.
Inspection: Test the physical and chemical properties of the silicone sealing ring to ensure that the expected effect of secondary vulcanization is achieved.Notes:
The temperature and time of secondary vulcanization need to be adjusted according to the specific type of silicone and product requirements.
Excessive temperature or time may damage the performance of silicone and require strict control.
During the secondary vulcanization process, it should be ensured that the silicone sealing ring is uniformly heated to avoid local overheating.
Through secondary vulcanization, the performance of the silicone sealing ring has been further optimized, improving its reliability and stability in various application environments.
Finally, enter the secondary vulcanization stage. The cleaned and treated initial vulcanized silicone rubber products are loaded into vulcanization molds and then heated to a certain temperature and time. During this process, the vulcanizing agent and accelerator react again, further enhancing the vulcanization degree of silicone rubber. At the same time, the cross-linking structure between silicone rubber molecules is further optimized, forming a more compact structure. This can not only improve the physical properties of silicone sealing rings, such as tensile strength, wear resistance, temperature resistance, etc., but also improve their chemical stability, enabling them to maintain good sealing performance in various environments.

The effect of secondary vulcanization is mainly reflected in the following aspects:
1. Eliminate the odor of curing agents and various additives in silicone rubber products, and improve the comfort of product use.
2. Reduce the size of silicone rubber products to make them more stable and meet the requirements of precision sealing.
3. Stabilize the physical properties of silicone rubber products and improve key indicators such as density, tensile strength, rebound, hardness, and swelling of silicone rubber products.
Furthermore, it is worth noting that different types of silicone sealing rings may require different secondary vulcanization conditions and parameters. Therefore, in the actual production process, appropriate vulcanization temperature, time, and type of vulcanizing agent should be selected based on the specific characteristics and requirements of the product to achieve the best secondary vulcanization effect.
In summary, the principle of secondary vulcanization of silicone sealing rings is to heat up to a certain temperature and time, causing the vulcanizing agent and promoter to react again, further enhancing the vulcanization degree and cross-linking structure of silicone rubber. This process is of great significance for improving the physical properties and chemical stability of silicone sealing rings. Through reasonable secondary vulcanization treatment, we can produce silicone sealing ring products with better performance and more comfortable use.