What is the selection of liquid silicone material for the secondary molding process of liquid silicone?

The secondary molding process of liquid silicone, as a precise and complex technology in modern manufacturing, places extremely high demands on the selection of liquid silicone materials. This process not only requires materials to have excellent physical and chemical properties, but also to exhibit good fluidity and adhesion during the molding process to ensure the quality and performance of the final product.

1、 Characteristics of Liquid Silicone Material

Liquid Silicone Rubber (LSR) is a highly active, viscous, and transparent organic silicon material, mainly composed of silicone resin, silane coupling agent, filler, and additives. Silicone resin, as its main component, endows liquid silicone with high stability, high transmittance, excellent weather resistance, and chemical corrosion resistance. In addition, silane coupling agents enhance the adhesion between the material and the substrate, fillers are used to adjust the physical properties such as viscosity and hardness of the material, and additives further improve the comprehensive properties such as weather resistance and chemical corrosion resistance of the material.

2、 Principles for material selection in the secondary molding process of liquid silicone gel

1. Good flowability: Liquid silicone gel needs to have good flowability during the injection molding process to ensure complete filling of the mold cavity and avoid defects such as bubbles and missing glue.
2. Excellent adhesion: During the secondary molding process, liquid silicone needs to be tightly bonded to the initially formed components or substrates, so the material is required to have excellent adhesion to ensure the overall strength and sealing of the product.
3. High stability: Liquid silicone gel needs to maintain chemical stability during the molding process to avoid decomposition or deterioration under high temperature and pressure, which may affect product quality.
4. Weather resistance and chemical corrosion resistance: As liquid silicone products may be used in various harsh environments, it is required that the material has excellent weather resistance and chemical corrosion resistance to extend the product’s service life.
5. Processability: Liquid silicone materials should be easy to process, including injection molding, vulcanization, cutting, and other processes, to improve production efficiency and reduce costs.

3、 The application advantages of materials in the secondary molding process of liquid silicone gel

1. Complex structure implementation: Through the secondary molding process of liquid silicone gel, components with complex structures and multiple layers of materials can be produced to meet the design requirements of different products.
2. High performance combination: Materials of different levels can be selected according to needs to achieve complementary functions, such as the combination of hardness and elasticity, and the balance between wear resistance and slip resistance.
3. Improve product added value: The excellent properties of liquid silicone, such as high transmittance and good tactile sensation, can significantly enhance the added value and market competitiveness of the product.

4、 Specific selection method of materials in the secondary molding process of liquid silicone gel

1. Determine product requirements: Firstly, clarify the product’s usage scenarios, performance requirements, and design requirements, such as hardness, viscosity, temperature resistance, chemical corrosion resistance, and other indicators.
2. Material performance testing: Conduct performance testing on candidate liquid silicone materials, including flowability testing, adhesion testing, stability testing, etc., to ensure that the materials meet process requirements.
3. Cost benefit analysis: Taking into account material costs, processing costs, and the market value of the final product, select the material with the best cost-effectiveness.
4. Supplier evaluation: Select liquid silicone material suppliers with good reputation and strong technical strength to ensure material quality and supply stability.

5、 Case analysis

Taking the combination of the anti drop frame and soft rubber back shell in mobile phone protective cases as an example, the secondary molding process of liquid silicone has played an important role in the production of such products. Firstly, inject a hard frame into the first mold as an anti drop frame; Subsequently, transfer the preliminarily formed frame to the second mold and inject liquid silicone to form a soft rubber back shell. The selection of liquid silicone material is crucial in this process. It is necessary to choose liquid silicone material with good fluidity, strong adhesion, and excellent weather resistance to ensure a tight bond between the frame and the back shell and the overall performance of the product.

6、 Conclusion

The secondary molding process of liquid silicone imposes strict requirements on the selection of liquid silicone materials. By deeply understanding the characteristics of liquid silicone materials, following selection principles, clarifying application advantages, and adopting scientific selection methods, it is possible to ensure that liquid silicone products achieve optimal performance and quality during the secondary molding process.