Halogenated fire retardants applications

The first fire retardant polyester containing a reactive fire retardant monomer was introduced by the Hooker Electrochemical Corporation in the early 1950 s containing chlorendic acid as the reactive monomer (6). This pioneering development rapidly led to the introduction of variety of reactive halogen and phosphorus containing monomers, such as tetrabromophthalic anhydride, chlorostyrene and tetrabromobisphenol A, which found application in a wide variety of condensation polymer systems. 

FIRE RETARDANT FILLERS. The next major fire retardant development resulted from the need for an acceptable fire retardant system for such new thermoplastics as polyethylene, polypropylene and nylon. The plasticizer approach of CP or the use of a reactive monomer were not applicable to these polymers because the crystallinity upon which their desirable properties were dependent were reduced or destroyed in the process of adding the fire retardant. Additionally, most halogen additives, such as CP, were thermally unstable at the high molding temperatures required. The introduction of inert fire retardant fillers in 1965 defined two novel approaches to fire retardant polymers. 

S.V. Levchik, D.A. Bright, G.R. Alessio, and S. Dashevsky, New halogen-free fire retardant for engineering plastic applications,. Vinyl Addit. Technol., 7(2) 98-103, 2001. 

Phosphate Esters. The principal advantage of phosphate esters is the improved fire retardancy relative to phthalates. The fire performance of PVC itself, relative to other polymeric materials, is very good due to its high halogen content, but the addition of plasticizers reduces this. Consequently there is a need, in certain demanding applications, to improve the fire-retardant behavior of flexible PVC. 

The market demand for halogen-free fire-retardant polymers has been increasing steadily in applications such as electrical/electronics, transportation, and construction products. In wire and cable, the high loadings of ATH or MDH are required (60-70 wt.%). Recent developmental efforts... 

Burning may be considered another means of oxidation. Non-burning plastics are a must in commercial constructions according to building codes and are often required for automotive, electronic, and electrical applications. From the numerous thermoplastics, only the halogen-containing polymers, polyamides, polycarbonate, poly(phenylene oxide), polysulfone, and polyimides are self-extinguishing. Even these, such as poly (vinyl chloride), may become flammable when plasticized with a flammable plasticizer. Fire control can be the key to volume use of plastics. Polyester panels, urethane foam, and PVC tarpaulins account for nearly 90% of all fire retardants consumed. Consumption in 1967... 

M.S. Cross, The Development and Application of Halogen-Free Tin-Based Fire Retardant Additives in EVA, Eng. D. Thesis, Brunei University, Uxbridge, UK, 2004. 

Polystyrene can be made into a veiy-low-density foam which has found use in electrical, sound, and heat-insulation applications. The inflammability is a definite setback for such applications, and experiments are under way to use halogenated polystyrene for such purposes or to incoiporate ifiert and fire-resistant or fire-retarding ingredients. Polystyrene foam can also be produced from expandable beads which contain an expansion... 

The use of fire retardant (FR) additives, and/or halogenated FR resins in gelcoats detracts from their weatherabiUty and for external applications it is good practice to achieve fire retardancy by using a highly FR laminating resin behind a non-FR gelcoat. 

The most effective fire-retardant polymeric materials are halogen-based polymers (e.g., PVC, chlorinated PVC, polyvinylidene fluoride (PVDF)) and additives (e.g., chlorinated paraffins (CPs), tetrabromobisphenol A (TBBA)). However, the improvement in fire performance depends on the type of fire tests, that is, the application. 

Zinc borate can be used as a fire retardant in PVC, polyolefins, elastomers, polyamides, and epoxy resins. In hal( en-containing systems, it is used in conjunction with antimony oxide, while in halogen-free systems it is normally used in conjunction with other FRs such as aluminum trihydrate, magnesium hydroxide, or red phosphorus. In a small number of specific applications, zinc borate can be used alone. 

Four halogen free, fire retardant resins, based on orthophthalic resin, filled with aluminium trihydrate. Approved for marine application by Det Norske Veritas. 

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