What is the appropriate time for injection molding vulcanization of liquid silicone package PC parts?

The injection molding vulcanization time of liquid silicone encapsulated PC parts is a complex and critical process parameter, which directly affects the quality and production efficiency of the product. We need to analyze from multiple perspectives, including the influencing factors of vulcanization time, the comparison of effects under different vulcanization conditions, and how to improve product quality and production efficiency by optimizing the vulcanization process.

1、 Factors affecting vulcanization time

The vulcanization time is an important step in the molding process of liquid silicone products, which is influenced by various factors including formula design, vulcanization temperature, vulcanization pressure, and vulcanization medium.

1. Formula design: The proportion and content of components such as silicone type, crosslinking agent, catalyst, and filler in the formula will directly affect the rate and degree of crosslinking reaction, thereby affecting the vulcanization time. Different formulations may require different vulcanization times to achieve optimal physical properties and chemical stability.

2. Sulfurization temperature: Temperature is one of the key factors affecting the vulcanization rate. Generally speaking, the higher the temperature, the faster the vulcanization rate. However, excessively high temperatures may lead to excessive cross-linking of silicone molecular chains, resulting in sulfurization and retrogradation, which can actually reduce product quality. Therefore, it is necessary to avoid the negative effects of high temperature while ensuring the vulcanization speed.

3. Sulfurization pressure: Sulfurization pressure also has a certain impact on vulcanization time. Appropriate pressure can promote close contact and cross-linking reactions between silicone molecules, thereby shortening the vulcanization time. However, excessive pressure may cause excessive compression of silicone, affecting the stability and performance of product dimensions.

4. Sulfurization medium: The choice of vulcanization medium also affects the vulcanization time. For example, the use of certain specific vulcanizing agents or catalysts can accelerate the vulcanization process, but may also have a certain impact on the physical properties of the product.

2、 Comparison of effects under different vulcanization conditions

In the actual production process, the vulcanization time of liquid silicone encapsulated PC parts usually needs to be adjusted according to the specific formula, product specifications, and production environment. The following is a brief comparison of the effects under different vulcanization conditions:

1. Low temperature long-term vulcanization: Long term vulcanization at lower temperatures can fully crosslink the silicone molecular chains and achieve higher physical properties. However, this method is time-consuming, has low production efficiency, and may cause product aging due to prolonged exposure to high temperatures.
2. High temperature short-term vulcanization: Short term vulcanization at high temperatures can significantly improve production efficiency, but excessively high temperatures may lead to excessive cross-linking of silicone molecular chains, resulting in vulcanization retrogradation and reducing the flexibility and aging resistance of the product.
3. Optimize vulcanization process: By adjusting the formula, optimizing vulcanization temperature and pressure parameters, it is possible to maximize production efficiency while ensuring product quality. For example, using efficient vulcanizing agents and catalysts can shorten the vulcanization time without affecting product quality; By precisely controlling the vulcanization temperature and pressure, problems such as excessive cross-linking and compression deformation can be avoided.

3、 Practice and Exploration of Optimizing Sulfurization Process

In order to optimize the vulcanization process of liquid silicone encapsulated PC parts, it is necessary to conduct practice and exploration from multiple aspects. Here are some effective optimization measures:

1. Formula optimization: By adjusting the proportion and content of silicone types, crosslinking agents, catalysts, and fillers in the formula, the vulcanization process can be optimized, the vulcanization time can be shortened, and the physical properties and chemical stability of the product can be maintained. For example, using high-performance silicone and crosslinking agents can accelerate the vulcanization reaction and improve production efficiency.

2. Temperature control: Accurately controlling the vulcanization temperature is the key to achieving efficient vulcanization. Advanced temperature control equipment and technology, such as PID temperature control systems, heating plates, etc., can be used to ensure the stability and accuracy of the vulcanization temperature. At the same time, select the appropriate vulcanization temperature range based on the specific requirements and formula characteristics of the product.

3. Pressure adjustment: By adjusting the vulcanization pressure, it is possible to promote close contact and cross-linking reactions between silicone molecules, thereby shortening the vulcanization time. However, it should be noted that excessive pressure may cause excessive compression of silicone, affecting the stability and performance of product dimensions. Therefore, it is necessary to choose the appropriate vulcanization pressure range based on the specific requirements and formula characteristics of the product.

4. Selection of vulcanization medium: Choosing the appropriate vulcanization medium can accelerate the vulcanization process while maintaining the physical properties and chemical stability of the product. For example, the use of certain specific sulfurizing agents or catalysts can accelerate the sulfurization reaction, but may also have a certain impact on the physical properties of the product. Therefore, when selecting a vulcanization medium, it is necessary to comprehensively consider its effectiveness, cost, and impact on product performance.

5. Process innovation: By introducing new process technologies and equipment, the vulcanization process can be further optimized. For example, the use of injection molding technology can achieve efficient and precise vulcanization processes; Advanced detection equipment and technology can be used to monitor real-time parameters such as temperature, pressure, and degree of vulcanization during the vulcanization process, ensuring the stability and consistency of product quality.

4、 Case analysis and practical experience

1. Formula adjustment: By optimizing the formula and using high-performance silicone and crosslinking agents, the speed and efficiency of the vulcanization reaction have been improved. At the same time, the amount of filler is reduced, the density and hardness of the product are lowered, and the flexibility and aging resistance of the product are improved.

2. Temperature control: Advanced PID temperature control system has been introduced to achieve precise control of vulcanization temperature. By adjusting the range of vulcanization temperature and heating rate, the vulcanization time has been shortened, while avoiding the phenomenon of vulcanization reversals caused by excessive temperature.

3. Pressure adjustment: Based on the specific requirements and formula characteristics of the product, a suitable range of vulcanization pressure has been selected. By precisely controlling the magnitude and rate of change of vulcanization pressure, the tight contact and cross-linking reaction between silicone molecules are ensured, improving the dimensional stability and performance of the product.

In summary, the vulcanization time during injection molding of liquid silicone encapsulated PC parts needs to be determined based on various factors. Manufacturers need to find the optimal vulcanization time and conditions through experimentation and experience to ensure that the quality and performance of the product meet the requirements.