Liquid silicone rubber has excellent transparency, tear strength, resilience, yellowing resistance, thermal stability, water resistance, good air permeability, heat aging resistance and weather resistance. At the same time, it has moderate viscosity, good fluidity, easy operation and high transparency.

The latest application and development of liquid silicone rubber

In recent years, liquid rubber injection molding (LIMS), that is, the injection molding of liquid silicone rubber, has been widely popularized and popularized. Recently, this method has become a widely concerned molding method in the industry because of its advantages of short-time automatic molding and composite molding with plastics. The latest trend of liquid silicone rubber injection molding and the materials suitable for this molding method will be introduced below.

Liquid silicone rubber material

1. Liquid injection molding of silicone rubber

Liquid silicone rubber injection molding, which started in the 1970s, is becoming more and more popular. Nowadays, as a molding method of silicone rubber, it has been recognized. Firstly, the commonly used LIMS method is explained.

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

(1) Labor saving: the processes of material conveying, metering, mixing and injection can be realized continuously and automatically to reduce power consumption.

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

(3) It can improve product quality: no reaction by-products are generated and no impurities are mixed.

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

2. Latest technical trends of LIMS

At present, it is not only transitioning from simple mixing type with the above advantages to LIMS method, but also actively developing in the following two directions recently.

(1) Full automatic molding: no flash, no runner, automatic demoulding

As for the fully automatic molding process, people have studied it from the aspects of injection machine, mold, material and so on. It can not only save manpower in process operation, but also reduce the material cost because it will not produce useless solidified products. From the perspective of taking into account environmental protection, this method has also attracted much attention. For the molding of micro products such as automobile skeleton oil seal, the molding cycle (from the injection to the next injection) is required to be within 10s, which can be completed in a very short time.

(2) Composite forming: clip 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. Since no by-products such as peroxide decomposition residue are generated in the crosslinking reaction, there is no need for secondary vulcanization in principle. Therefore, it can be integrally formed with resin, and inlay formed by coating primer materials, so that the sealing part and skeleton part become a whole. Binary forming has also begun to be popularized.