Trends of Development of Silicone Rubber Technologies

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At present, the trend of world’s organic silicone material’s technologies is to develop high-efficiency, multifunctional and composited technologies. It is to match progression of technologies and adding additives, and to change crosslinking methods, to copolymerization, and to alloy which are all modifying technologies to realize the composition of organic polymer materials and organic silicone materials. It is the important direction of development of organic silicone materials. The scientists are designing different organic silicone products which contain different molecular structures to fulfill different demands which come from different situations.

In the recent years, even though the number of organic silicone products is increasing, however, they could be categorized into 3 types of new technologies which are applied in new organic silicone oil material application developments.

Cross-linking Method

The traditional method of Room-temperature Vulcanized silicone rubber (RTV) is through the condensation between silanol group and alkoxy, now, the new technology which is to use the additional reaction between hydrogen and vinyl has made better efficiency to compare with the traditional method. Additional reactions could control the speed rate of solidification and there are no side materials to be produced. Thus, it could increase the electrical properties and heating resistance of manufactured products. For example, Toray Organic Silicone use organic siloxane which contains Si-H key and vinyl to manufacture polysiloxane; GE of the U.S. applies new zeroth order nickel complex catalytic agents to make new additional type silicone rubber; 3M manufactures additional products by using Si-H key compounds and alkenyl compounds. Some particular physical properties have evident enhancement. As for condensation, there are also some new-developed cross-liking agents. For example, TSE39X series products announced by Japanese is one series of non-corrosive fast-dry sealing agents which have been improved a lot.

Also, to target at fast solidification and energy saving, some countries are focusing more on the cross-linking methods which are via solidification between EB and UV. The cross-linking of EB will not bring any impurities and could react deeper under room temperature. Some nations’ EB cross-linking methods could be made to use high-strength silicone rubbers which have better properties. The tensile strength is 10MPa, the tensile rate is 500%, the tearing strength is 25kN/m and the highest is 43kN/m. However, EB needs big devices and only big companies or organizations could afford. In recent years, the more active one is the light cross-linking method, it is based on UV as the energy and the device is simple with a low operation cost. For each mol photon (365nm) only needs tens of cents, and to get macromolecular cross-linking result which has a square of 0.5㎡ and a thickness of 100μm. For a more meaningful aspect, the cross-linking speed of light is fast and could bring solidification on belt or thread type samples under room temperatures like cables and adhesive paper. Thus, it could be used for photocopying and semi-conductor’s photoetching.

Chemical Modification on Polymers

To bring some long-chain alkoxyl and other organic functional groups to the main chains of siloxane is a common way to grant special interfacial activities to the formed modified silicone oil. In recent years, siloxanization technologies could be very active in organic composition. It allows the past difficult organic composition to be easier to achieve. Therefore, it attracts the interests from the public on compositions on organic silicone compounds which contain different chemical keys. Recently, there is a new type of product called blend polymer. One example is the modified rubber which is modified from organic silicone and EPDM; it could fix both of two materials’ shortages. What is more, when we combine polysiloxane and macromolecules by chemical keys or other stable ways, we could lead PDMS’s some properties to macromolecule to get new polymers to be used for the modification of macromolecules. It is since the chain of PDMS is very soft; its activity of functional group is bigger and thus easier to react with many types of macromolecules. Therefore, the studies of combination of polysiloxane and organic macromolecules are rapidly increasing and there are many relevant doctrines in recent years. Some of the aspects are shown below:

1.      To enhance plastics. To bring some PDMS, to improve the toughness of engineering plastics.

2.      To enhance rubbers. To increase the strength of rubbers.

3.      To improve surface properties. To lead some PDMS into some macromolecules, even though there may be only 1% ~ 3%, it could make its surface to be more lubricant and lower its friction coefficient.

4.      To be used as medical materials.

Compounding Techniques & New Additional Agents

The number of new examples of progressions of compounding techniques and adding new additive agents is increasing recently. For example, to add silica to develop electrical-conduction silicone rubbers, then to develop the keyboards to PC, the controller of clocks, the circuit opens to TV and many other products.

By adding some new additives to change or improve some properties of some organic products also bring very practical consequences. At present, the major nations are all adding different types of additive agents to enhance the thermal stability of silicone rubbers and all get better results. For instance, the U.S. DC & GE companies apply two or over two types of composited metallic compounds to allow silicone rubbers could be used for a long-term period under 275℃; China has tried to add some self-developed additive agents to make the heating resistance time of silicone rubber to be double or be four times more under 250~350℃.

Summary

We could see that the relevant advanced technologies of silicone rubbers are growing fast and many people start to focus on these areas to try to find more efficient & effective ways in their manufacturing processes or market penetrations. Not only RTV and HTV, but also other modified silicone rubbers are also being redeveloped and researchers are trying to make more adjusts on them to get new materials with other better both of physical & chemical properties for further purposes.