Flame retardants silicon compounds

In the case of flame retardant silicone elastomer, many ingredients such as silica, platinum, and other flame retardant agents are incorporated into the base siloxane polymer. But there is no need to use the halogenated flame retardant agent, for example, bromine or chlorine compounds. This difference is an advantage of silicones compared with other synthetic polymers in terms of health and safety. 

This paper reports the results of a molecular-level investigation of the effects of flame retardant additives on the thermal dedompositlon of thermoset molding compounds used for encapsulation of IC devices, and their implications to the reliability of devices in molded plastic packages. In particular, semiconductor grade novolac epoxy and silicone-epoxy based resins and an electrical grade novolac epoxy formulation are compared. This work is an extension of a previous study of an epoxy encapsulant to flame retarded and non-flame retarded sample pairs of novolac epoxy and silicone-epoxy compounds. The results of this work are correlated with separate studies on device aglng2>3, where appropriate. 

Acohols - [ALCOHOL FUELS] (Vol 1) - [FEEDSTOCKS-COALCHEMICALS] (Vol 10) - [DISTILLATION, AZEOTROPIC AND EXTRACTIVE] (Vol 8) - [COALCONVERSIONPROCESSES - LIQUEFACTION] (Vol 6) - [FLAME RETARD ANTS - PHOSPHORUS FLAME RETARD ANTS] (Vol 10) - [EXPLOSIVES AND PROPELLANTS - PROPELLANTS] (Vol 10) -as antifreeze [ANTIFREEZES AND DEICING FLUIDES] (Vol 3) -for automotive motor fuel [FUELS, SYNTHETIC - LIQUID FUELS] (Vol 12) -from castor oil [CASTOR OIL] (Vol 5) -in ceramic processing [CERAMICS - CERAMIC PROCESSING] (Vol 5) -from hydrocarbon oxidation [HYDROCARBON OXIDATION] (Vol 13) -as hypnotic and sedative [HYPNOTICS, SEDATIVES, ANTICONVULSANTS, AND ANXIOLYTICS] (Vol 13) -m metal polishes [POLISHES] (Vol 19) -from oxo process [OXO PROCESS] (Vol 17) -permanganate oxidation [MANGANESE COMPOUNDS] (Vol 15) -reactions with silanes [SILICON COMPOUNDS - SILANES] (Vol 22) -role m mineral processing [MINERALS RECOVERY AND PROCESSING] (Vol 16)... 

Minor industrial uses include the application of silver iodide as a smoke for the seeding of clouds to induce rainfall. Compounds used for obtaining some nonflammable plastics and cellulose are benzyltriphenyl-phosphoniumiodides and [2,-(acetyloxy)ethyl] triphenyl-phosphoniumiodides (see Flame RETARDANTS, HALOGENATED FLAME retardants) (142). The addition of iodine to an aromatic hydrocarbon such as -butylbenzene results in the formation of charge-transfer complexes that display outstanding effectiveness as lubricants for hard-to-lubricate metals (143), such as titanium or steels (see also LUBRICATION AND LUBRICANTS). Iodine is also used in the production of high purity metals such as titanium, silicon, hafnium, and zirconium (144). 

Metal hydroxides in combination with various silicon-containing compounds have been used to reduce the amount of additive required to achieve a required level of flame retardancy in a variety of polymeric materials, including polyolefins.62-63 Systems that have been used contain a combination of reactive silicone polymers, a linear silicone fluid or gum, and a silicone resin, which is soluble in the fluid, in addition to a metal soap, in particular magnesium stearate. However, there is little insight given into how these formulations work. 

Elastomers. Many applications of rubbers such as tires, gaskets, and washers normally do not require flame resistance. When improvement in flammability is required, it can be achieved by the addition of halogen-containing materials, phosphorus compounds, oxides of antimony, and combinations of these materials. Rubbers containing chlorine and silicon atoms, for example. Neoprene and Silicone, have self-extinguishing properties. Rogers and Fruzzetti (10) described the flame retardance of elastomers. 

Liquid immersed types use various forms of oil and special synthetic liquids. The chlorinated liquids, e.g. polychlorinated-biphenyl, have been banned in most countries because they are very strong pollutants and are almost impossible to destroy, except by intensive burning in a special furnace. Modern liquids are synthetic compounds typically silicone based, and are usually specified to be flame retardant. 1EC60296, 60836, and 60944 describe suitable liquids. These transformers are the type normally used in oil and gas plants. Resin insulated transformers are very suitable for indoor locations and off-shore plants because they contain no flammable liquid, produce no spillage and require minimal maintenance. They are usually more expensive than conventional liquid immersed transformers. 

Aluminium is a non-essential element for anything living and is abundant in soil, and hence plants absorb a lot of it. Its absorption by the body is prevented by silicon and enhanced by citric acid, which forms a soluble compound. Aluminium, once in the body, is difficult to remove, but is still not regarded as a poison at normal levels (approximately 60 mg in the whole body). Aluminium oxide is used as a flame-retarding additive in plastics. 

Other chemical treatments may also be employed for more specific purposes for example, proprietary treatments, usually involving silicone or PTFE, enhance yam-to-yam or fibre-to-fibre lubricity during pulse or flex cleaning, and similarly, where flammability is a potential hazard, padding through commercially available flame retardant compounds may be necessary. 

Silicon elastomers, in contrast to the public opinion, are actually able to spread flame, depending on the lengths of their hydrocarbon side-chains. Their smoke-production is negligible. They can be flame-retarded with brominated aromatics, antimony trioxide, bismuth and arsenium compounds. 

Work in Russia has shown that the use of elemental silicon plus tin chloride can enhance the flame retardancy of both polypropylene and polyamide 66 compounds. Silicon tetrahalides are formed in the gas phase of combustion and inhibit the chain reactions that develop in a fire. These silicon halides do not act like halogen hydrocarbons in the atmosphere so there is no likelihood of contributing to ozone depletion. 

Phosphorus compounds are often combined with silicon rather than nitrogen, as in European Patent 899301 from General Electric, in which a polyester moulding compound is flame retarded with an organoclay, a polymeric siloxane composition and a boron and phosphorus containing material. 

General Electric s Patent EP862185 concerns flame retardant based on an aryl-containing silicone, which may contain triphenyl or diphenyl groups, together with a diorganic polysiloxane compound. It is claimed to improve the flame retardancy of polycarbonate without losing the transparency. 

Dow Coming Toray Silicone in Japan has proposed the use of a silicone-based FR for polycarbonate compounds. A heat treatment at 380 °C for polycarbonate containing the silicone material has been shown to generate a phenyl silyl ether linkage that appears to lead to flame retardancy for the formulation. 

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