Additives flame retardant applications

Only about 1% of PP volume consumed employs any flame retardancy additives. Flame retardant applications for PP are proportionately much less important than for other resins such as styrenics and engineering thermoplastics less than 5% of the total FRs consiunption is used in PP. 

An important use of bromine compounds is in the production of flame retardants (qv). These are of the additive-type, which is physically blended into polymers, and the reactive-type, which chemically reacts during the formation of the polymer. Bromine compounds are also used in fire extinguishers. Brominated polymers are used in flame retardant applications and bromine-containing epoxy sealants are used in semiconductor devices (see... 

Hrominaied Additive Flame Retardants. Additive flame retardants are those ihut do not react in die application designated. There are a lew compounds lhal can be used as ail additive in one application and as a reactive in nlmlher. Teirabromobisphenol A iTBBPA) is the most notable example. Table I lists the properties of most commercially available bromine-containing additive flame retardants... 

Triphenylphosphate is a colorless, odorless, crystalline solid (mp, 49°C bp, 245°C). It is moderately toxic. A similar, but much more toxic, compound is tri-o-cresyl-phosphate (TOCP), an aryl phosphate ester with a notorious record of poisonings.3 Before its toxicity was fully recognized, TOCP was a common contaminant of commercial tricresylphosphate. Tricresylphos-phate is an industrial chemical with numerous applications and consists of a mixture of phosphate esters in which the hydrocarbon moieties are meta and para cresyl substituents. It has been used as a lubricant, gasoline additive, flame retardant, solvent for nitrocellulose, plasticizer, and even a cooling fluid for machine guns. Although modem commercial tricresylphosphate contains less than 1% TOCP, contaminant levels of up to 20% in earlier products have resulted in severe poisoning incidents. 

Applications In 1994 about half of the Phosphorus(III) chloride consumed in the USA was utilized in the manufacture of the intermediate phosphorous acid, a further 19.4% to phosphorus(V) oxychloride. Di and trialkylphosphonates, triarylphosphonate, pho.sphorus(V) sulfochloride and phosphorus(V) chloride are also manufactured directly from pho.sphorus(III) chloride. Broken down according to the field of application of the end products, the consumption of phosphorus(IIl) chloride is the USA in 1994 53.6% was utilized for pesticide production (mainly for glyphosphate), 18% for the manufacture of water treatment chemicals (phosphonic acids) and tensides (acid chlorides of fatty acids and secondary products), 17.1% in the manufacture of polymer additives (flame retardants, stabilizers etc.) as well as small quantities for the production of hydraulic fluids, lubricants and additives for lubricating oils. 

BPC is a very versatile molecule that can be used to produce a variety of polymeric materials with inherently low levels of flammability, allowing them to be used with no additional flame retardant in some applications. 

It is clearly a truism that for reducing the fire risk in the applications of plastics, their flammability should be diminished. This is achieved either by reactive flame-retardants incorporated during the preparation (polymerization, polyaddition, polycondensation) of the polymer or by additive flame-retardants admixed in the course of plastics processing. The flammability of plastics is sometimes reduced by surface protection. The most recent methods of reducing flammability are the modification of the macromolecular structure and the development of thermally resistant polymers (high-temperature plastics). 

Additive flame-retardants are physically admixed with the polymer in the course of processing. Their main advantage lies in the versatility of their applications, i.e. the processor is free to select the type and amount of the additive according to... 

Halogenated Aliphatic Phosphates and Phosphonates. The principal use of these additives is in polyurethane foams broader reviews of this important flame retardant application area have been published (70,71). 

Other hydroxy aromatics in addition to bisphenol A, such as phenol [135], cresols [136], and chlorinated compounds useful in flame-retardant applications [137], have been reported to be used to give epoxy compounds,... 

Melamine Flame Retardants Melamine is a unique product with 67 wt% nitrogen in the molecule and fairly high thermal stability. Melamine also forms thermally stable salts with strong adds. Melamine itself, melamine cya-nurate, melamine phosphate, melamine pyrophosphate, and melamine polyphosphate are commercially available for various flame retardant applications. The mechanism of flame retardant action of melamine is different from the mechanism of melamine salts or may be part of the mechanism of action of ihe salts. In addition, melamine phosphates have specific advantages because of the presence of phosphorus in the molecule. 

It is has been demonstrated that the addition of small quantities of carbon nanotubes (CNTs) can dramatically improve the thermal and mechanical properties of polymers. " In many cases, however, this enhancement of properties is limited by the degree to which the CNTs can be dispersed uniformly within the polymer matrix. This appears to be particularly true for flame-retarding applications. For example, Kashiwagi and co-workers demonstrated that the heat release rates from burning well-dispersed nanocomposites consisting of single-walled CNTs (SWCNTs) in poly (methyl methacrylate) were significantly lower than... 

Since polymer nanocomposites have been unable to meet regulatory fire tests by themselves (Chapters 5 and 11), additional flame retardants (Chapter 1) have been necessary (Chapters 6, to 9) to allow them into commercial use and end-use applications (Chapters 6 and 11). 

In light of the issues with natural clays, one likely trend is an increase in the use of synthetic clays, such as fiuorinated synthetic mica, magadiite, and layered double hydroxides (LDH). This last clay, since it has the potential to release water under fire conditions [much like Mg(OH)2 or Al(OH)3], may find even more use in flame retardant applications. Cost issues and limited sources for synthetic clays will slow the adaptation of these materials, so most of the work will probably be seen in the patent or open literature. More work will be seen for nanocomposites containing nanofillers, such as carbon nanotubes and nanofibers, and these will probably also be combined with additional fiame retardants. 

PBBs are primarily added as additive flame retardants, for example to acrylonitrile-butadiene-styrene polymers, which have found applications in the automotive industry, electronics and coatings. Since the 1970s, there has been stagnation in the production of PBBs, and the last known commercial production of decaBB was completed in France in 2000. 

HBCD has been used as an additive flame retardant for more than 20 years. Its main use is in the construction industry, where it is used in polystyrene foams, which are a part of the thermal isolations, and even small concentrations provide sufficient protection against burning. The second major application of HBCD is in the upholstery and textile industries. Products in which the HBCD occurs, for example, include upholstered furniture, various textiles, car seats and upholstery, insulation in trucks and caravans as well as many types of building materials. Unlike other flame retardants, HBCD is not used in electronic circuits. 

Other studies on the flame retardant applications of phosphazene derivatives include the use of cyclotriphosphazenes to improve the flame-retardant properties of epojy composites,using fluorinated phosphazene derivatives as non-flammable electrolytes in lithium ion batteries and utilizing phosphazenes as flame-retardant additives in curing polysiloxanes. °... 

Vamac polymers are halogen- tee and therefore do not promote corrosion and are suitable for use in noncorrosive, flame-retardant applications. The permeability of Vamac to gases is low, compared with that of butyl mbber. In addition, AEM compounds have good adhesion to a variety of metals, fibers, and other elastomers. Mineral-filled compounds of Vamac can be brightly colored and are capable of maintaining their color quality after thermal aging. 

Other factors affect resin selection for flame-retardant applications. PVC is often compounded with other additives to improve flame and smoke properties. Flame-retardant loadings exceeding 50 phr are not uncommon in riser jacketing applications... 

Organic polymers provide one of the most versatile groups of materials and have widespread uses. Due to some inherent deficiencies, mainly poor heat and flame resistance, these materials suffer from limitations in certain areas of application. The resistance of polymers to high temperatures and flame may be increased by the incorporation of both aromatic rings and certain chemical elements in the polymer chain. It has been found that phosphorus, present either as a constituent in the polymer chain or incorporated as an additive in the form of a phosphorus compound to the polymer system, can make polymers flame retardant [109]. 

Paints are complex formulations of polymeric binders with additives including anti-corrosion pigments, colors, plasticizers, ultraviolet absorbers, flame-retardant chemicals, etc. Almost all binders are organic materials such as resins based on epoxy, polyurethanes, alkyds, esters, chlorinated rubber and acrylics. The common inorganic binder is the silicate used in inorganic zinc silicate primer for steel. Specific formulations are available for application to aluminum and for galvanized steel substrates. 

Recent advances in the application of ultrafine talc for enhanced mechanical and thermal properties have been studied [12]. A particularly important use is of finely divided filler in TPO as a flame-retardant additive. In a representative formulation, 37 parts of E-plastomer, Ml 2.0, density 0.92, 60 parts of amorphous EPR, and 4 parts of fine carbon black were dry blended, kneaded at 180°C, pelletized, and press molded into test pieces, which showed oxygen index 32 versus 31 in the absence of a filler. The oxygen index is a measure of flame retardancy. 

Mention has already been made of the application of alkoxycyclophos-phazenes, [NP(OR)2] , as flame retardants in rayon. Although the methoxy-derivatives, with their high phosphorus content, were expected to be most efficient in this respect, their water solubility proved a major shortcoming. However, the n-propoxy series, [NP(OPr )2] ( mainly 3—6), were found to impart excellent flame resistance and were well retained by rayon. The cyclophosphazene alkoxides were obtained by the addition of sodium-n-propoxide to the chloride homologues, (NPCl2)n, and were added to the viscose dope before the rayon was spun. The flame resistance imparted by various amino- and thioalkoxy-derivatives was also tested, but found to be inferior to the results obtained with alkoxy-deriva-tives. Several patent applications have resulted from work on this topic. ... 

Additives are needed not only to make resins processable and to improve the properties of the moulded product during use. As the scope of plastics has increased, so has the range of additives for better mechanical properties, resistance to heat, light and weathering, flame retardancy, electrical conductivity, etc. The demands of packaging have produced additive systems to aid the efficient production of film, and have developed the general need for additives which are safe for use in packaging and other applications where there is direct contact with food or drink. 

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