Liquid silica gel products are favored by more and more people because of their excellent product properties, such as tear resistance, resilience, yellowing resistance, thermal stability, heat resistance and aging resistance. From the early mother and baby liquid silica gel products, more and more liquid silica gel products appear in our life. Liquid silica gel has the characteristics of good fluidity and quick vulcanization, so it is more difficult to manufacture liquid silica gel products than solid silica gel products. So, how are liquid silicone products made? How is it formed?
In the molding process of liquid silica gel products, the typical heating room is electric heating, which usually adopts electric heating wire heater, heating pipe or heating plate. In the one-time curing process of liquid silica gel, it is very important to distribute the temperature evenly in the mold. In large dies, the most economical heating method is oil temperature control.
According to different vulcanization methods, silica gel can be divided into two categories: high temperature vulcanized silica gel and room temperature vulcanized silica gel. No matter which type of silica gel, no exothermic phenomenon occurs during vulcanization. High-temperature vulcanized silica gel is polysiloxane with high molecular weight, while room-temperature vulcanized silica gel generally has low molecular weight, with one or two functional groups at both ends of the molecular chain. Under certain conditions, these functional groups can react to form a cross-linked structure with high molecular weight.
Room temperature vulcanized silica gel can be divided into condensation type and addition type according to its vulcanization mechanism, and can be divided into two types: two-component and one-component according to its packaging mode. The properties of silicon-oxygen bonds constituting the main chain of silica gel determine that silica gel has the advantages that natural rubber and other rubbers do not have. It has the widest working temperature range and excellent high and low temperature resistance.
In the temperature range, silicone rubber can not only keep certain softness, resilience and surface hardness, but also have no obvious change in mechanical properties, and can resist long-term thermal aging. If the mold is designed by a cold runner system, it is necessary to have a suitable gap between the cold and hot interfaces. For the whole mold heating system, an insulating layer should be placed between the mold and the template to minimize the heat loss.