In the process of customized silica gel products production, the process of silica gel products determines its value and market. At present, liquid injection molding and solid-state molding are more common processing methods. Food grade liquid silica gel is made of platinum catalyst. The processing technology of the product can be said to be a high-quality one at present. Compared with understanding the processing process of silicone rubber products For people, as long as we can accept the production and processing costs, we will basically choose liquid silica gel technology. What is the outstanding advantage of this process?










Liquid silica gel has the advantages of transparency, tear resistance, resilience, anti yellowing, thermal stability, water resistance, good permeability, aging resistance and weather resistance, and moderate viscosity, good fluidity, easy operation and high transparency of products.






Liquid injection molding of liquid silica gel, which started in 1970s, has been widely used. Nowadays, as a molding method of silicone rubber, it has been recognized. Firstly, the LIMS method is widely used.






If LIMS (liquid silicone rubber injection molding) is explained in one sentence, it is the method of pump to transfer the added solidified liquid silicone rubber to the injection molding machine and solidify it in the model. From the process flow and the difference of curing reaction between the two methods, LIMS has several advantages:






(1) Saving manpower: continuous automation of material conveying, metering, mixing and injection processes, reducing power consumption






(2) Can improve production efficiency: through rapid curing to seek to shorten the molding cycle.






(3) Can improve product quality: no reaction by-products, no impurities mixed






(4) Suitable for composite molding: because of the good fluidity of materials, low forming pressure and wide curing temperature range, composite molding can be carried out in addition to embedded parts forming.










2. The latest technology trends of LIMS






At present, not only is the transition from simple mixing type with the above advantages to LIMS method, but also is developing to the following two directions






(1) Automatic molding: no flying edge, no runner, automatic demoulding






About the automatic forming technology, people have studied from injection machine, mould, material and other aspects. It can save manpower not only in process operation, but also because it will not produce useless solidified materials, so the cost of materials is reduced. From the perspective of environmental protection, this method has attracted much attention. For the molding of micro silicone products such as skeleton oil seal for automobile, the molding cycle (from injection to the next injection) is required to be within 10s, so that it can be completed in a very short time






(2) Composite forming: clamp insert forming and binary forming






Because the crosslinking reaction is in the form of addition curing, it can be formed at a relatively low temperature. In principle, secondary vulcanization is not necessary because of the no peroxide decomposition residue and other by-products in the cross-linking reaction. Therefore, it can be integrated with resin, and inlaid by coating the primer material, so that the sealing part and the skeleton part become a whole dual forming has also begun to be popular






Silicone rubber products have excellent properties (heat resistance, plug resistance, weather resistance, electrical insulation, flame retardant, etc.). Because of these properties, it is possible to make the environmental protection forming based on automatic forming and the whole forming of metal and organic resin










The material itself is transparent and colorable, so its application range covers many fields, such as (computer, mobile phone, etc.) silicone key, silicone nipple, (copier, printer, etc.) rubber roller, pipe joint seal, oil seal and other automobile silicone sealing accessories, television picture tube anode cap, diving supplies, etc.






3. Materials without glue edge / automatic forming without runner






In recent years, in the injection molding of liquid silicone rubber, a method called non glue edge and no runner forming has been widely used. This is a molding method which does not produce useless solidified materials and does not need to be processed twice. It is a molding method without filling port, flow channel (even if there is no solidification) and no waste glue edge. In order to implement this molding method, the accuracy of the measurement and discharge of the injection machine must meet the requirements for the construction of the model and the finish of the parting surface, and even in the material aspect, it must be the material that is difficult to generate the waste adhesive edge










The results show that after the glue entering the mold cavity is filled with the mold cavity, the rubber material flows into the parting surface due to the excessive glue material or the thermal expansion of silicone rubber, and then becomes the waste adhesive edge after curing. If the parting surface is designed to be narrow, the waste rubber edge will be difficult to generate, but at the same time, the air is not easy to be discharged, so it will become the original cause of containing bubbles in the finished product






Compared with the previous materials, the curing curve of the material is in a rapid turning state (from the beginning of curing to the end of curing is very short). By selecting the appropriate injection conditions of such materials, that is, before the material is filled with the mold cavity, the curing has not started and the material flow is good. When the material is filled with the mold cavity, the curing will end immediately. Even if there is residual pressure, the material will not flow to the parting surface to prevent the formation of waste adhesive edge.