Engineering plastics flame retardants

Mixed esters, such as isopropylphenyl diphenyl phosphate and tcrt-butylphenyl diphenyl phosphate, are also widely used as both plasticizers/flame retardants for engineering thermoplastics and hydraulic fluids.11 These esters generally show slightly less flame-retardant efficacy, when compared to triaryl counterparts however, they have the added advantage of lower smoke production when burned. Some novel oligomeric phosphate flame retardants (based on tetraphenyl resorcinol diphosphate) are also employed to flame retard polyphenylene oxide blends, thermoplastic polyesters, polyamides, vinyls, and polycarbonates. 

Brominated compounds will continue to hold much of the engineering plastics sector and thereby some dominance in the electrical and electronics (E E) sector. They will continue to be the most significant products because they are the most cost effective (and efficient) solution to many plastics flame retardancy applications. The EU Waste Electrical and Electronic Equipment (WEEE) directive and its effect on recycling plus the debate about fire safety versus environmental issues (especially in domestic appliances) will continue to attract much attention. 

The UL flammability ratings describe the relative ease of ignition and combustibiUty of plastics. Tests include the measurement of flame propagation, time to self-extinguish, melt and drip with and without flame, and oxygen indexes. Some engineering plastics, eg, polyetherimides, are, as ranked by this test, inherently nonflammable. Others can be made nonflammable by compounding with flame retardants (ERs) such as bromine... 

Brominated phosphate heated in a glass tube in air at 300°C for 30 minutes remains a water-white liquid. This was compared with commercial bromine-containing flame retardants which melt they all turn color. The excellent color stability of this brominated phosphate ester makes it suitable for the high temperature processing of engineering plastics. 

Fire behaviour of products constitutes a major and permanent preoccupation in multiple areas building and construction, transport, electric and electronic engineering, furniture, etc. This theme possibly involves the largest number of standards, regulations or legislations at national level as well at international level. It is in this context that the use of flame retardants for plastics must be envisaged. Several themes are outlined. 

Smith, R. Georlette, P Finberg, I. Reznick, G. Development of environmental friendly multifunctional flame retardants for commodity and engineering plastics. Polymer Degradation and Stability, 1996, 54(2-3), 167-173. 

Stinson, J.M. and Horn, W.E. Flame retardant performance of a modified aluminum hydroxide with increased thermal stability, Proceedings from Society of Plastics Engineers 52nd Annual Technical Conference (ANTEC 94), Part 3, Newtown, CT, U.S.A, May 1-5, 1994, pp. 2829-2833. 

Shen, K.K. 2006. Overview of flame retardancy and smoke suppressant in flexible PVC. Society of Plastics Engineering Vinyltech Conference, Atlanta, GA, October 18. 

Polyolefin (PO) foams are tough, flexible, and resistant to chemical and abrasion however, they are characterized by a low inherent fire resistance and hence quite high amounts of flame-retardants are needed to fulfill fire safety requirements. Therefore, when fire requirements are stringent, generally styrene and engineered plastics are used in spite of polyolefin foams because, for example, for complying UL 94 V-0 rating, 30%-40% fire retardant is normally required for PO foams while only 10%-20% FR additives are required for styrenic foams.91... 

The most popular materials are styrenics and olefins, and engineering plastics such as modified polyphenylene ether or polycarbonate (Chapter 2). Fillers for enhanced physical properties, UV stabilizers, and flame retardants are common additives. 

Retardants are mainly used as additives for plastics, particularly those used in the manufacture of electrical and electronic equipment. FRs are added to circuit boards, cables, coimectors, plugs, and house component devices. These compounds are used in the production of engineering plastics, thermoplastic and elastomeric elements, and insulation. Flame retardants can also be found in furniture, mattresses, carpets, curtains, clothing (mainly protective or sweatshirts for children), and polymeric materials used for the production of cars, buses, airplanes, and military equipment. FRs have been used wherever material must meet safety standards regarding flammability [87]. 

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