In-depth Analysis of Liquid Silicone Packaging Process: How to Empower High-end Manufacturing and Product Innovation

In the wave of modern manufacturing towards high-precision, high-performance, high-value-added transformation, materials composite technology is becoming the core engine driving product innovation. Liquid Silicone Rubber (LSR) As a new elastomeric material with excellent physical and chemical properties, it is combining with traditional thermoplastics to produce the cutting-edge process of LSR overmolding. This technology, known as plastic-coated silicone or "hard and soft bonding", not only breaks the performance limitations of a single material, but also has triggered profound industrial changes in the fields of medical, automotive, consumer electronics, and baby and child products. As a cultivator in the rubber and plastics industry, Dongguan Fengyanda Life Technology Co., Ltd. will deeply analyze the technical principle, core advantages of this process and its application prospects in the 2027 market trend. I. Liquid silicone: From single material to composite process, the cornerstone liquid silicone is a two-component, additive cured silicone material. Compared with traditional solid silica gel, it has the remarkable characteristics of low viscosity, good fluidity, fast vulcanization speed and no by-product release. These characteristics enable LSR to fill extremely complex mold cavities with precision injection molding equipment, enabling micron-level precision control. More importantly, liquid silicones have excellent resistance to high and low temperatures (-50°C to 200°C), excellent electrical insulation, excellent biocompatibility, and excellent anti-aging properties. However, single materials are often difficult to meet the dual demands of modern products for structural strength and surface feel. For example, medical devices require both a rigid skeleton to support the internal components and a soft contact surface to enhance patient comfort; car keys require both a stable internal structure and good sealing and feel. It is in this context that the liquid silicone plastic coating process came into being. It combines the softness, sealing and weather resistance of LSR with the rigidity and dimensional stability of engineering plastics (such as PC, ABS, PA, PBT, etc.) to achieve a "1 +1 2" performance leap. 2. Liquid silicone coated plastic: technical principle and process challenge Liquid silicone coated plastic is essentially a secondary injection molding process (Two-shot Molding or Overmolding). The core process is usually divided into two steps: first, a plastic substrate (Substrate) is molded through a conventional injection molding process; then, the substrate is placed or retained in a mold and injected with liquid silica gel for secondary molding, so that the silica gel forms a solid chemical or mechanical bond with the plastic surface. This process seems simple, but the technical control is extremely demanding. The first challenge is bond strength. Since silicone and most plastics are non-polar materials, they naturally lack affinity. If not handled properly, delamination and degumming are very likely to occur. The key to solving this problem lies in the pretreatment and modification of the material surface. Current mainstream solutions include the addition of special adhesion promoters to plastic substrates, plasma or flame treatment of plastic surfaces to increase surface energy, and the use of specially designed self-adhesive LSR materials. Secondly, mold design and temperature control are also the keys to success. There is a significant difference in shrinkage between the two materials during the silicone encapsulation process (plastics typically range from 0.5% -1.5%, while LSR is about 2% -3%). If the mold design does not fully consider the thermal expansion coefficient matching, internal stress is easily generated after cooling, resulting in product warping or cracking at the joint. In addition, the vulcanization temperature of LSR is usually between 120 ℃ and 180 ℃, and the glass transition temperature of some engineering plastics is low, which requires that the mold must have accurate partitioning and temperature control capabilities to ensure that the silica gel is fully vulcanized without damaging the plastic substrate. III. Core advantages and application scenarios of plastic coated silicone The reason why plastic coated silicone technology can occupy a place in the field of high-end manufacturing is due to the multiple core values it brings: The ultimate ergonomic experience: In handheld devices, power tool handles, toothbrush handles and other products, rigid plastics provide structural support, while the outer liquid silicone layer provides a slip-resistant, shock-absorbing and skin-friendly touch, which greatly enhances the user's comfort. Excellent sealing and protection performance: In the fields of waterproof electronics, automotive sensors, medical catheters, etc., LSR and plastic integrated molding eliminates the seams in traditional assembly, achieving IP67 and even IP68 dust and waterproof effects, while simplifying the assembly process and reducing production costs.

Double enhancement of aesthetics and functions: Through two-color or multi-color injection molding, liquid silicone plastic can achieve rich color matching and texture effects, without subsequent spraying to achieve high-end appearance. At the same time, the light transmittance of silicone can also be used to make light guide buttons or indicator lampshades, which have both decorative and functional properties.

In specific applications, the medical industry is the biggest beneficiary of LSR encapsulation technology. For example, breathing masks, infusion tube connectors, surgical instrument handles, etc., all require materials that are non-toxic, odorless, and can be sterilized at high temperatures. The perfect characteristics of liquid silicone make it the best choice. In the field of new energy vehicles, components such as battery pack seals, charging gun housings, and in-vehicle touch panels are also adopting plastic packed silicone technology on a large scale to cope with harsh environmental tests and improve interior texture. 4. Trend outlook for 2027: Intelligentization and greening look forward to the future, and the liquid silicone packaging plastic process will develop in a more sophisticated, smarter and greener direction. With the advancement of Industry 4.0, the intelligent monitoring system will collect pressure, temperature and flow data in the injection molding process in real time, and automatically optimize process parameters through AI algorithms, thereby greatly reducing the defective rate and improving production efficiency. At the same time, the increasingly stringent environmental regulations will also promote the innovation of materials. The combination of bio-based plastics and recyclable LSR will become a hot spot in the industry, aiming to achieve low carbon emissions throughout the product life cycle. Dongguan Fengyanda Life Technology Co., Ltd. will continue to pay attention to this trend, increase investment in research and development of high-performance composite materials and precision molds, and strive to provide customers with more competitive liquid silicone packaging plastic solutions. The cross-border integration of liquid silicone and engineering plastics is not only an advancement in materials science, but also an innovation in manufacturing processes. Liquid silicone coated plastic (i.e., plastic coated silicone) technology is reshaping product standards across multiple industries with its unique performance advantages. For manufacturers, mastering this core process means mastering the key to the high-end market. In the future competition, only by constantly improving technology and deepening applications can we be invincible in the fierce market torrent.