2019-12-07

Liquid silica gel has excellent transparency, tear strength, resilience, yellow resistance, thermal stability, water resistance, good air permeability, heat aging and weather resistance, while moderate viscosity, good mobility, easy to operate, high product transparency.The latest application development of liquid silicone rubberIn recent years, liquid rubber injection molding method (LIMS), namely liquid silicone rubber injection molding has been widely popularized.Recently, because this method has the advantage that can carry on a short time to form automatically and compound with plastic to form, become the molding method that the personage inside course of study pays close attention to commonly.The following is an introduction to the latest trends in liquid silicone rubber injection molding and the materials suitable for this molding method.1. Liquid injection molding of silicone rubberLiquid silicone rubber injection molding method, which started in the 1970s, was gradually popularized. Now, as a molding method of silicone rubber, it has been recognized.In one sentence, explain LIMS(liquid silicone rubber injection molding), which is the method of pumping the solidified liquid silicone rubber into the injection molding machine and curing it in the model.From the perspective of the process flow of the two methods and the difference in curing reaction, LIMS has several advantages:(1) labor saving: the process of material transportation, measurement, mixing and injection can be continuously automated to reduce power consumption.(2) can improve the production efficiency: through rapid curing to shorten the molding cycle. (3) product quality can be improved: 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 a wide range of curing temperature, in addition to the embedment molding can also be composite molding.2. Latest technology trends of LIMSAt present, it is not only transitioning from pure mixing type with the above advantages to LIMS method, but also developing in the following two directions.(1) fully automatic molding: no flash, no runner, automatic strippingAbout the fully automatic molding process, people from the injection machine, mold, material and other aspects of the study.It not only saves manpower in process operation, but also reduces the cost of materials because it does not produce useless curing materials. From the perspective of environmental protection, this method has also attracted much attention.For the molding of micro-products such as automotive skeleton oil seals, the molding cycle (from injection to the next injection until) is required to be less than 10s, which can be accomplished in a very short time.(2) compound forming: clamping insert forming and binary formingBecause the crosslinking reaction is in the form of additive curing, it can be formed at relatively low temperatures.Since there is no peroxide decomposition residue and other byproducts in the crosslinking reaction, secondary vulcanization is unnecessary in principle.Therefore, it can be molded with resin as a whole, and inlaid with coated base coating material, so that the sealing part and the skeleton part become a whole binary molding has also begun to be popular.Silicone rubber has excellent properties (heat resistance, plug resistance, weather resistance, electrical insulation, flame retardant, etc.).Because of these properties, it is possible to make environmentally friendly forming based on automatic forming, with metal, organic resin integral forming.In addition, the material itself is transparent with colorability, so its application range involves many fields, such as (computer, mobile phone, etc.) keys, milk bottle nipple, (copier, printer, etc.) cots, tube joint seals, oil seals and other auto parts, TV tube anode cap, diving supplies, etc.3, no rubber edge/no flow channel for automatic forming materialsIn recent years, in the field of liquid silicone rubber injection molding, a method called glue-free edge, no flow channel molding has become popular.This is a molding method that does not produce useless solidification and does not require secondary processing, that is, it is a molding method that does not have injection port, flow channel (even if there is no solidification), and does not produce waste rubber edge.In order to implement this molding method, the structure of the model and parting surface such as the smoothness, the injection machine measurement, discharge accuracy must meet the requirements, even in the material must be difficult to generate waste rubber edge of the material.As shown in FIG. 2(omitted), after filling the mold cavity, the rubber material into the mold cavity, due to excessive rubber material, or due to the thermal expansion of silicone rubber and other factors, the rubber material into the parting surface, after curing will become waste rubber edge.If divide a face to design some narrower, waste gum edge is generated hard, but at the same time, the air also is not easy platoon go, become the reason that bubble contains in the finished product then.Compared with previous materials, the curing curve of this material is in a rapid transition state (from the beginning of curing to the end of curing is very short).Through the selection of the appropriate injection conditions for this material, that is, before the material fills the cavity, the curing has not begun, the material liquidity is very good, and when the material fills the cavity, the curing immediately ends, even if there is residual pressure, the material will not flow to the parting surface, to prevent the formation of waste plastic edge.
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