Fire retardants reactive

Reactive polyols which contain halogen groups, phosphorus, or both, are offered by a number of suppliers for flame-netardant urethane-foam applications. These materials can be used alone, or with other flame retardants as synergists. Although reactive flame retardants may appear to be more costly initially, in the long run they may be found to be less expensive than the additive types (31). 

---

Polyether Polyols. Polyether polyols are addition products derived from cyclic ethers (Table 4). The alkylene oxide polymerisation is usually initiated by alkah hydroxides, especially potassium hydroxide. In the base-catalysed polymerisation of propylene oxide, some rearrangement occurs to give aHyl alcohol. Further reaction of aHyl alcohol with propylene oxide produces a monofunctional alcohol. Therefore, polyether polyols derived from propylene oxide are not truly diftmctional. By using sine hexacyano cobaltate as catalyst, a more diftmctional polyol is obtained (20). Olin has introduced the diftmctional polyether polyols under the trade name POLY-L. Trichlorobutylene oxide-derived polyether polyols are useful as reactive fire retardants. Poly(tetramethylene glycol) (PTMG) is produced in the acid-catalysed homopolymerisation of tetrahydrofuran. Copolymers derived from tetrahydrofuran and ethylene oxide are also produced. 

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. 

FIGURE 2.3 Structures of comonomers used for reactive fire retardant studies of Price et al.75 77 (From Price, D. et al., Polym. Adv. Technol., 19(6), 710, 2008.)... 

Thermosets. Fire retardancy in thermosetting polymers is achieved largely by the use of reactive fire retardants because the common fire-retarding additives lack permanence. The flammability of thermosetting materials can be reduced by the additions of inorganic fillers and/or reactive flame retardant components. Flame-retardant vinyl monomers or other cross-linking agents are also frequently employed. 

A medium-to-high reactive, fire retardant (ATO + chi. par.) isophthalic resin with low profile... 

A white, free flowing paste-like solution or dispersion of thermoplastic polymers and fillers for low-shrink application in highly reactive fire retardant, SMC/BMC and puitrusion resin systems. 

The reaction with sodium sulfite or bisulfite (5,11) to yield sodium-P-sulfopropionamide [19298-89-6] (C3H7N04S-Na) is very useful since it can be used as a scavenger for acrylamide monomer. The reaction proceeds very rapidly even at room temperature, and the product has low toxicity. Reactions with phosphines and phosphine oxides have been studied (12), and the products are potentially useful because of thek fire retardant properties. Reactions with sulfide and dithiocarbamates proceed readily but have no appHcations (5). However, the reaction with mercaptide ions has been used for analytical purposes (13)). Water reacts with the amide group (5) to form hydrolysis products, and other hydroxy compounds, such as alcohols and phenols, react readily to form ether compounds. Primary aUphatic alcohols are the most reactive and the reactions are compHcated by partial hydrolysis of the amide groups by any water present. 

Flame Retardants. Although the use of chlorinated derivatives of DCPD has been restricted in the pesticide area, some are widely used in flame and fire retardant chemicals (see Flame retardants). The starting material is the fliUy chlorinated DCPD cracked to monomeric hexachlorocyclopentadiene, which is then converted via a Diels-Alder reaction with maleic anhydride to a reactive bicycHc anhydride (9), known as chlorendic anhydride [115-27-5]. 

Aryloxyphosphazene copolymers can also confer fireproof properties to flammable materials when blended. Dieck [591] have used the copolymers III, and IV containing small amounts of reactive unsaturated groups to prepare blends with compatible organic polymers crosslinkable by the same mechanism which crosslinks the polyphosphazene, e.g. ethylene-propylene and butadiene-acrylonitrile copolymers, poly(vinyl chloride), unsaturated urethane rubber. These blends were used to prepare foams exhibiting excellent fire retardance and producing low smoke levels or no smoke when heated in an open flame. Oxygen index values of 27-56 were obtained. 

Most circuit boards are FR-4 boards that meet standards for fire safety by the use of brominated epoxy resins in which the reactive flame-retardant tetrabromobisphenol A (TBBPA) forms part of the polymeric backbone of the resin. Alternative flame-retardant materials are used in only 3-5 per cent of the FR-4 boards, but additional alternative flame-retardant materials are also imder development. Little information exists concerning the potential environmental and human health impacts of the materials which are being developed as alternatives to those used today that are based on brominated epoxy resins. 

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. 

Functionalized polymers are of interest in a variety of applications including but not limited to fire retardants, selective sorption resins, chromatography media, controlled release devices and phase transfer catalysts. This research has been conducted in an effort to functionalize a polymer with a variety of different reactive sites for use in membrane applications. These membranes are to be used for the specific separation and removal of metal ions of interest. A porous support was used to obtain membranes of a specified thickness with the desired mechanical stability. The monomer employed in this study was vinylbenzyl chloride, and it was lightly crosslinked with divinylbenzene in a photopolymerization. Specific ligands incorporated into the membrane film include dimethyl phosphonate esters, isopropyl phosphonate esters, phosphonic acid, and triethyl ammonium chloride groups. Most of the functionalization reactions were conducted with the solid membrane and liquid reactants, however, the vinylbenzyl chloride monomer was transformed to vinylbenzyl triethyl ammonium chloride prior to polymerization in some cases. The reaction conditions and analysis tools for uniformly derivatizing the crosslinked vinylbenzyl chloride / divinyl benzene films are presented in detail. 

In conclusion, I have attempted to demonstrate that bark can be used as the sole polyol component in the production of rigid polyurethane foam. These foams possess good physical as well as inherent fire retardant properties. With the availability of bark as a reactive polyol, I can see a means of utilizing bark as a cheap raw material in producing economical polyurethane foam products. 

With regard to reactive flame-retardants, two routes can be followed to improve thermal stability and fire behavior of PU foams use of brominated or phosphorus-containing polyol or, for rigid foams, the introduction inside polymer backbone of more thermally stable structure than urethane, mainly isocyanurate, but also uretidione rings or carbodiimide.19... 

Luda, M.P. Costa, L. Bracco, P. Levchik, S.V. Relevant factors in scorch generation in fire retarded flexible polyurethane foams II Reactivity of isocyanate, urea and urethane groups. Polym. Degrad. Stab. 2004, 86, 43-50. 

Due to more stringent fire regulations in many countries and the increased use of plastic materials and synthetic fibres, the use of flame retardants has increased. In 1992,600,000 tons of flame retardants were used worldwide, 150,000 tons were brominated compounds. 50,000 Tons of these were the reactive flame retardant with TBBPA and its derivatives and 40,000 tons were PBDEs [1]. 

Flame-retardant rigid foams can be classified by the testing methods employed, but the results do not reflect actual fire situation. Fire-retardant rigid urethane foams can be prepared by using flame retardants of the additive type, reactive type, or a combination thereof. A review of flame retardants for polyurethane foams has been prepared by Hilado (154). 

---