1. The meaning of selective bonding materials
Through direct molding of silicone rubber and plastic or metal without primer, their integral molding can be obtained. In the past, the one-piece molded product obtained in this way has structural limitations. After the primer is applied to the injection-molded product, there will be a problem of spots, and the adhesiveness will change with the drying state. Defects such as The adhesive silicone rubber material is solved, and the self-adhesive liquid silicone rubber material can be directly molded with various types of substrates at one time.
2. Bonding structure
1. Substrate
For nylon, polycarbonate (PC), aluminum, and glass, injection molding is performed by the method shown in the figure below, and it can be obtained that the mold or mold surface material has almost no adhesion to nickel or chromium. For nylon, PC, metal, Nylon glass fiber and PC glass fiber have good bonding properties.
2. Structure
The silane coupling agent (CF silane) is used as a primer or an additive, and its bonding mode and bonding performance depend on the mechanism of the silane coupling agent. As shown in the figure below, it has a base that reacts with organic materials and inorganic materials. There are also groups that react with metals (Metal-OH) and glass (Si-OH), so that there is a certain interaction between various materials (chemical reaction, hydrogen-oxygen bonding, force between molecules), but cannot Bonding with metal is the characteristic of the selected bonding material, so CF silane cannot be used as the bonding agent, and other materials can be selected as the medium for metal bonding. In addition, by combining the adhesive and the bridge, the interaction with the resin component (compatibility with the resin, intermolecular force, etc.) is particularly strong. Bonding system with bonding performance.
3. Process comparative analysis
Self-adhesive liquid silicone rubber and general liquid glue (need to brush primer)
01Material selection
(1) Self-adhesive: the preferred choice for major terminal customers such as iphone, Huawei, etc.
(2) Primer + ordinary liquid glue: general choice for mid-range customers
(3) Primer + general rubber compound: material selection for low-end market
02Energy saving
The self-adhesive adopts a low-temperature platinum vulcanization system, which reduces the electric heating energy consumption required for production by about 30%
03Environmental protection
In contrast to the other two options, self-adhesive liquid silicone rubber does not require the use of a primer. Compared with the double 2-penta-vulcanized rubber compound system, the environmental protection advantages are more obvious (the double 2-penta-penta-vulcanized rubber system will have the risk of residual peroxide in the product), and the anti-yellowing effect is more excellent
04Production efficiency
Self-adhesive liquid silicone rubber has lower vulcanization temperature requirements and shorter vulcanization time than ordinary liquid rubber, and saves the operation time of manual primer coating. Efficiency is more obvious!
After testing, MSK liquid self-adhesive silicone rubber has a good bonding effect with plastic or metal materials, which meets the manifestation of "silicone + plastic (metal) dual-material characteristics".