Fire-Protective and Flame-Retardant Coatings – A State · PDF fileFire-Protective and Flame-Retardant Coatings ... A formulation of 18.6% rutile (TiO 2), 12.7% barium metaborate,

Fire-Protective andFlame-Retardant Coatings – AState-of-the-Art ReviewEDWARD D. WEIL*

Polymer Research Institute, Polytechnic Institute of New York University, SixMetroTech Center, Brooklyn, NY 11201, USA

(Received September 1, 2010)

ABSTRACT: This review covers mainly intumescent coatings, with brieferdiscussions of non-intumescent organic fire-resistive coatings and cementitiousinorganic coatings. Emphasis is placed on the more recent developments, and themore recent patent literature is surveyed. Modeling and optimizing are coveredboth from basic and applied aspects. The chemistry of the production of a foamedchar barrier is discussed. Enhancing the performance by adjuvants and choice ofbinders is shown to be possible. The important interactions of ammoniumpolyphosphate with other components such as titanium dioxide are described.Testing is briefly discussed, as are some shortcomings of present-day coatings,such as limited water resistance, and some opportunities for improvement.

KEY WORDS: intumescent coatings, spumific, carbonific, ammonium poly-phosphate, heat transfer, melamine, char, adjuvants, silicates, borates, titaniumdioxide, expandable graphite, binders, ceramic coatings, textile coatings,firestops, gelcoats.

INTRODUCTION AND SCOPE

PASSIVE FIRE PROTECTION includes coatings and firestops, as well as theuse of inherently flame-retardant materials. Flame-retardant plasticsand textiles have been covered in a recent book by Weil and Levchik [1].Fire-retardant coatings for wood have been briefly reviewed in the

*E-mail: [email protected]; [email protected]

JOURNAL OF FIRE SCIENCES, VOL. 29 – May 2011 259

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broader context of fire safety of wood construction by USDA ForestProducts Laboratory researchers in the 2010 Wood Handbook [2]. Woodcoatings more often are designed to retard ignition and rate of burnrather than to provide the fire-resistive barrier which is more typical ofsteel coatings.

Traditional fireproofing coatings are cementitious coatings, based onPortland cement, magnesium oxychloride cement, vermiculite, gypsum,and other minerals. Fibrous fillers, supplementary binders, and density-controlling and rheology-controlling additives are typically mixed withwater on site and applied by spraying during steel construction atthicknesses of one-half inch or more. The Underwriters Laboratories FireResistance Directory calls them Spray Fire Resistant Materials (SFRMs).Some of these coatings can be applied onto a flammable substrate by theuse of rollers and/or a moving belt. These coatings can provide fireprotection from one-half to several hours by water release and thermalinsulation effects. They are low in cost and easy to apply, and some areresistant to weather exposure. However, because of their weight,thickness and poor esthetics, they limit architectural design. Buildingdesigners avoid them for visually exposed steel. They may also bedislodged in a violent fire. Further discussion of these mineral coatingsis outside the scope of the review, as are rigid mineral-based boards, fireblankets, or loose-fill flame-retardant insulation as passive fire protection.A useful although brief discussion of SFRMs as well as intumescentcoatings and their UL classification is found in a Carboline paper [3].Firestops and flame-retardant gelcoats are briefly discussed in this review.

This review will put the main emphasis on coatings, particularlyintumescent coatings (which swell to a thick insulative foam whenheated above a critical temperature), but will briefly discuss other typesof coatings which are flame retardant but not intumescent. Both thesetypes of non-mineral coatings can be applied by qualified painters, andcan offer good appearance and durable surfaces. The US market hasbeen underdeveloped for intumescent coatings for steel in buildingsbecause of the predominance of concrete construction, relative cost, andpossibly lesser familiarity by architects.

Another main classification of fire-protective coatings is based ontheir desired performance, namely: (1) those that increase the fireresistance as defined by ASTM E119 for buildings or by ASTM E1529 forhydrocarbon fires and measured in terms of time, i.e., 1 h, 2 h, etc., and(2) those that reduce the flame spread of the combustible substrate, suchas wood, as measured by the flame spread index of ASTM E84 in theUSA. Fire-protective coatings can also be classified from the standpointof the type of fire being protected against: (1) the ‘wood fire’ such as

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might occur from burning furniture, paper, cloth, etc., (typicallyrepresented by the E119 test, discussed later), and (2) the ‘hydrocarbonfire’ from burning petroleum (typically assessed by the E1529 test, alsodiscussed later). Both classifications have considerable overlap.

Typically, coatings protective (or retardant) against cellulosic-typefires are applied in thin film coats up to 1.5 mm (60 mils) thick. Thesecoatings are usually not very weatherable; so, for outdoor applications, aprotective topcoat is needed. Coatings protecting against hydrocarbonfires are typically two-component (usually epoxy) systems appliedsolvent-free at 8–10 mm (320–400 mils) per coat often through separateheated lines with an in-line static mixer at the spray tip. The steelsurface should be prepared by an abrasive blast, and then ananticorrosive primer should be applied. After application of the fire-protective coating, a topcoat (for example, an acrylic polysiloxane finish)may be applied. These coatings may be applied off-site or after the steelframework has been erected. A properly applied coating of this type issuitable for offshore oil and gas facilities, being quite resistant tohydrocarbons and to seawater.

BACKGROUND

The classical review of intumescent coatings is a 1971 paper byVandersall [4] (Monsanto). He presents the early history and thedetailed course of development of commercial intumescent coatings,mostly based on a char-forming carbonaceous material (‘carbonific’), amineral acid catalyst, a blowing agent (‘spumific’), and a binder resin.This review is replete with formulations and is still a rich source forideas for formulation improvement. At the time of Vandersall’s review,typical commercial intumescent paint formulations contained severalpounds per gallon of intumescing components, and required thick andcostly coatings. Much empirical research has been done in industry anda few academic laboratories to optimize intumescent coatings, to findalternative char-formers, catalysts and blowing agents, optimizedbinders, activators, and residual barrier-forming additives. Parallelwork has been done outside of the coatings area to apply theintumescent approach to flame-retarding polyolefins, olefin copolymers,elastomers, and ‘firestops’ (barrier materials for closing wall apertures).We have reviewed polyolefin flame retardancy previously in this journal[5] and, with elastomers included, in a subsequent book [1]. In view ofthis prior coverage, this review will concentrate on coatings with someattention to firestops.

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More recent reviews have covered, usually not in the detailof Vandersall, the commercial applications of fire-retardant andfire-resistive coating. It is our intention to emphasize the more recentdevelopments and those which seem to be of greatest practical value.The theoretical and basic topics are covered by reference to publishedstudies without repeating them in any detail.

A useful review from a commercial viewpoint has been presented by amarketing manager in this field [6]. The importance of architecturaldesign – the esthetics of exposed steel – is discussed, as well as thequestion of on-site versus factory application.

Fire protection engineering overviews, comparing cementitious fire-protective coatings to intumescent coatings, are available from bothbefore [7] and after the 9-11-01 disaster. Subsequent to 9-11-01, muchattention was given to this question; a critical review by the NationalInstitute of Standards and Technology was published in 2004 [8] and isavailable as a book.

A 2007 review [9] of specialty coatings for fire protection covers theentire range of fire-retardant and fire-protective coatings, with realisticdiscussion of needs, markets, market dynamics and trends, codes andother regulatory issues, and types of products available, with profiles ofmajor US suppliers and their product lines.

NON-INTUMESCENT FIRE-RETARDANT COATINGS

A broad but not highly detailed overview of flame-retardant/fire-resistive coatings is presented by Green [10] who showed that evenconventional paints can reduce flame spread below that of an unpaintedflammable substrate, but for demanding situations such as on ship-board, coatings deliberately formulated for low flame spread index arepreferred. On shipboard, paint is repeatedly applied to preventcorrosion, and fire-resistant coatings using halogen–antimony flame-retardant systems are commonly used. The halogen component may be avinyl chloride–vinyl acetate copolymer, a chloroparaffin, or a chlorine-containing alkyd. Formulations are given for fire-retardant latex paintand alkyd-based paint. Formulations of this sort used by the US Navyand improvements in the 1990 period have been described in 1996 [11].A typical shipboard paint of a type probably still used by the Navy (MIL-DTL-24607B) [12] contains a chlorinated alkyd such as Reichhold’sBecksol" 91160-00, titanium dioxide, alumina trihydrate (ATH),magnesium silicate, calcium borosilicate (Halox" CW-2230), calciummetaborate (Buckman’s Flame Block" BL-381, various pigments,

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thixatropes, surfactants, solvents (such as Oxychem’s Oxsol" 100,p-chlorobenzotrifluoride), and driers shown in the specifications.

Coatings using high mineral loadings are another means for attainingflame resistance. A formulation of 18.6% rutile (TiO2), 12.7% bariummetaborate, 8% aluminum silicate pigment, 21.1% polyvinyl alcohol(PVA), and several wetting agents and dispersants with 25.2% waterwas published for an interior flat wall paint in 1992 [13].

Resistance to ignition and flame spread on wood is said to be providedby an aqueous coating using ATH, antimony trioxide, and calciumcarbonate with a vinylidene chloride–acrylate binder in a 1987 patent[14]. The coating is said to be suitable for exterior application.

A German research institute [15] has developed a fire-protectivecoating for wood based on ceramicizing compositions of sodium borateand silica plus optional phosphorus ester or salt components, usingvarious aminoplast or urethane resins as binders.

A commercial additive CEEPREE", a borosilicate glass with lowsoftening point, has been available since its original development at ICI[16]. This additive is useful, for example, in mastics for protection ofsteel against very hot (fuel) fires, providing some protection afterorganic material has burned away [17].

Protection of metals from corrosion while avoiding fire propagationcan be accomplished by a thin coating of ethylene–chlorotrifluoroethy-lene copolymer (Solvay Solexis’s Halar"), which chars when exposed tofire. Even coatings as thin as 10 mils can be effective [18].

Basic Studies on Intumescent Coatings

Basic research has been of two main types, one emphasizing the heattransfer aspects and the other the chemical aspects. A broad reviewdealing with both aspects, as well as practical considerations, has beenpublished by a University of Lille group [19].

Heat Transfer Studies With Intumescent Coatings

A group experienced with aerospace vehicle protection developeda semi-empirical computer model of the intumescent coating perfor-mance taking into account mass and heat transfer, swelling kinetics,and the reradiation of incident energy when a highly emissive charwas formed. Experimental weight loss measurements and estimatedthermophysical and chemical parameters were used as input, andthe model was shown to predict backface thermal histories to within20% of the experimentally measured values. Total expansion and rate


of expansion were found to be important parameters for providingthermal protection [20].

Another group with aerospace background conducted an extensiveexperimental program together with a simplified heat- and mass-transfermodeling (a ‘frontal model,’ assuming a thin pyrolysis region whichmoves from the coating’s surface to the substrate) [21]. The experimentalwork used a heat source typical of aviation fuel fires and measured thetemperature–time history of the substrate. A range of coatings werestudied; classical intumescents as well as silicate–borate systems. Onesalient conclusion was that the binder is critical. Another was that largeexpansions are not necessary and can even be detrimental if the charbecomes too frangible. The utility of the frontal model was confirmed.

A related study confirmed the utility of the thin zone model, andmathematical transforms reduced the model to one which was easilyamenable to numerical analysis. It was shown that although endother-micity of the foaming process is helpful, it is not essential and the modelfits well to experiment if adiabatic ‘tumescence’ is assumed [22]. A latermodeling study [23] assumed the intumescent reaction to be analogousto a phase change process occurring over a finite temperature range andexperiment showed that the substrate temperature could be accuratelypredicted by suitable choice of latent heat and temperature range for theintumescent reaction. The model of reference [22] can be taken as aspecial case of the later [23] model.

A subsequent Russian study [24] takes more account of thelocal viscoelastic properties of the foaming mass, heat conductivity, andthe chemical kinetics. Using a new mathematical algorithm developed bythese workers, a better fit was obtained of the computed data to theexperimental data on a boron-containing intumescent phenol–formalde-hyde coating. New observations on the morphology of the foam alsoprovided insights into the details of the intumescent process.

Basic studies in Russia have also been done on particular features ofintumescence. The effects of viscosity and surface tension, and of thedispersity of solid particles have been examined [25], and thecombustion characteristics of the char were also studied [26].

The effect of a surface coating of polytetrafluoroethylene on anotherwise intumescent coating was shown, interestingly, to prevent orretard the intumescence but nevertheless a heat-protective char coatingwas formed [27].

A detailed comparison and modeling by Koo [28] of the fire-protectiveproperties of two commercial intumescent coatings led to the conclusionthat the better performing material had larger expansion and nocontraction as well as lower thermal conductivity.

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A two-dimensional model was developed in an Australian engineeringschool [29] for studying the heat transfer through epoxy sublimingand intumescing coatings. Two different commercial coatings wereevaluated in regard to temperature and surface profiles under flamingconditions and found to fit well to the model provided thatdelamination did not occur. A later model by the same researchers[30] incorporated kinetic equations and produced a good fit ofconversion under isothermal conditions, except during initial stages ofintumescence and sublimation. Further refinement of the model [31]showed that atmospheric oxygen content is a major factor.

A generalized pyrolysis model was developed more recently atBerkeley [32] which can cover a charring (wood) substrate, a non-charring poly(methyl methacrylate) substrate, and intumescent coat-ings, and has an encouraging correlation to experimental data.

A model for the intumescence process with ammonium polyphosphate(APP) and pentaerythritol in polypropylene (not specifically acoating) was developed by Lille researchers [33] taking into accountkinetics and phase changes. Reasonable correspondence of computerand experimental temperature profiles lend support to themodel. Intumescence was shown to occur mainly between 2808Cand 3508C, and then degradation of the intumesced coating between3508C and 4308C by the further action of the flame. Above 4308C,structural changes occurred in the char. Further modeling by thisgroup [34] took account of anisotropy from the presence of carbonnanotubes, non-woven fabrics, and intumescent paint on steel, usingthe modeling and simulation heat transfer module of a particularsoftware package. A further study by this group [35] was directedtoward a broader elucidation of the mechanism of action of intumescentcoatings.

A mathematical model designed to be applicable to systems forprotecting against fast violent heating and explosions as encountered inmilitary situations was developed in France [36]. It showed promise butwas said to need further studies to improve accuracy.

A study published in 2009 discussed the effects of partial fireprotection on temperature development in steel joints protected byintumescent coating [37].

Heat Transfer and Combustion Kinetics of a Non-phosphorusIntumescent System

An intumescent fire-resistance coating for steel based on polychlor-oprene, ATH, and expansible graphite was studied and shown to


undergo three consecutive first-order steps on heating to 873 K – releaseof water from ATH, release of hydrogen chloride, and release of gasesfrom the graphite expansion [38]. All these processes retarded theheating of the steel substrate.

Optimization Studies of the Ingredient Ratio of APP Systems

In a Russian study, the optimum weight ratio of APP (or somemelamine organophosphonate salts) and polyol for both thermalprotection and oxygen index was found to be 7 : 3 for pentaerythritol,glycerol, and PVA [39].

An intricate optimization study involving computation as well asexperiment was published by Horacek [40] in 2009 in which hepostulated, and in some cases supported experimentally, a number ofplausible stoichiometric relationships of APP, polyol, and melamine, andtitanium dioxide as well as heat of combustion relationships. Themethodology is intricate and cannot be easily summarized but theconclusion was that a lower temperature-reacting polyol would beadvantageous; glycerol used along with the pentaerythritol was said toimprove the performance, allowing lower temperature (3008C) formaximum expansion whereas with the pentaerythritols, maximumexpansion required 3908C. The implication was that the required dryfilm thickness and number of coats could be reduced.

Mechanical Strength of Intumescent Chars

The mechanical stability (measured work required to crush the charfrom a urea–formaldehyde intumescent formulation) was also found atthe optimum APP-to-polyol ratio, but (not surprisingly) a moreexpanded foamed char was easier to crush. The mechanical strengthof various types of chars in the hot and cold states was investigated by aRussian group [41,42]. The technique used a controllable crushingdevice developed for food (presumably baked goods) testing. In a furtherstudy by this group, mathematical modeling was done on the charformation; smaller pores were found to be beneficial to mechanicalstability [43]. A mathematical model of the bubble phenomena wasdeveloped by these researchers [44]. Radiant heat within the bubbleswas shown to be the main mode of heat transfer [45]. An apparentlymore predictive algorithm for modeling the intumescence process wasdeveloped by a Russian–Kazakh group taking account of the localchange of viscosity (found from viscosity isotherms) which affects localexpansion [24].

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A systematic study at the University of Lille (2006) [46] usedthermogravimetric analysis (TGA), rheometry, and mechanical strengthtesting, with statistical methodology, to address the problem ofbalancing the desirable expansion with the desirable strength of theintumesced foam. The results correlated well with industrial furnacetests. A more recent study by the same group [47] of the kinetics ofpyrolysis led to development of a predictive model for the degradation atdifferent heating rates.

ADJUVANTS IN INTUMESCENT SYSTEMS – ACADEMIC ANDOTHER BASIC STUDIES

Much development of such systems has been outside of the coatingsfield and rather, directed to thermoprocessed polymer systems such aswire and cable jackets, building materials, and automotive or aerospaceplastics. Nevertheless, it is quite likely that non-coating findings may beapplicable to coatings and, at the risk of some overlap with our previousreview [5] and book chapter [1] on polyolefins, this review willencompass them.

Researchers at Lille (France) found that zeolites such as 4A (Na Azeolite) has a very strong synergistic effect in a classical APP/pentaerythritol intumescent system in polyethylene. The zeoliteencourages formation and stabilization of ‘phosphocarbonaceous’structures giving an improved intumescent shield, which also decreasesthe fuel feeding the flame [48]. The same researchers found a veryhelpful effect of including polyamide-6 in an intumescent APP/ethylene–vinyl acetate system, where the polyamide-6 and APP interacted to forma second heat-protective shield in addition to that formed from theethylene–vinyl acetate APP interaction [49].

Although not explicitly on coatings, a relevant study was done inpolypropylene by University of Turin researchers in collaboration withHimont researchers [50] on the effect of a series of inorganic fillers in anAPP–aminoplast resin intumescent system. Calcium phosphate, beingunreactive, was found not to spoil the flame-retardant action, whereastalc and calcium carbonate, which modified the chemistry of the system,were deleterious. A layer of polyphosphoric acid on the char surface wasbeneficial to its insulating action. The heat reflectance characteristics ofthe char were also shown to be of importance.

A subsequent study at Hoechst Celanese [51] also done in moldedpolypropylene, compared and interpreted the effects of several inorganicadditives on char formation in an intumescent system based on APP


and a char-forming polyol. Targeted features for an optimum char weredense compact outer crust with no porosity, interior sections with ahighly ordered cellular network, and mass. Tin dioxide was antagonisticby chemical interaction without bridging of polyphosphate, causingporous flaky char, whereas TiO2 was beneficial, attributed to bridging ofthe polyphosphate.

A research group at a Polish institute [52] recently claimed abeneficial performance effect in APP-based intumescent coatings byaddition of 0.2–5% nano-scale silica and also by addition of ahydrophilicizing surfactant 2,4,7,9-tetramethyl-5-decin-4,7-diol (AirProducts Surfynol" 104).

Chemistry of the Classical Char-Former, Char-Catalyst,and Blowing Agent Systems

The general outlines of this intumescent coating chemistry weredescribed in the classical Vandersall review. In its most general andoversimplified summary, an acid-generating catalyst, most commonlyAPP reacts with a polyol to initiate dehydration to a carbonaceous char,and a blowing agent such as melamine or an HCl-releasing polymer oradditive generates gas in the molten mass to make a foam whichsolidifies from the melt to make a heat- and vapor-transfer barrier.

Subsequently, detailed studies of the chemical steps were made byCamino’s group in Turin (1984–1990) [53] and by the research group atUniversity of Lille (2004) [54]. Both groups relied heavily on thermalanalysis and spectroscopic methods. In this review, we will not repeat adiscussion of this readily accessible work, but to address some of the lessobvious features.

The Behavior of APP When Heated

Based on laboratory-scale thermal studies, such as by the Turinresearchers [55], APP loses ammonia along with water, and in severalstages forms a crosslinked polyphosphoric acid. Actually, the thermalbehavior of APP is quite complex and much depends on whether theammonia is in any way constrained. With even light constraint, as in aloosely capped vessel or a polymer matrix, enough ammonia remainschemically bonded such that in the extreme case, the end product is aceramic-like material, phosphorus oxynitride (PON)x [56–58]. Theintermediate steps seem not to have been well investigated althoughthe formation of a P–N bonded glass has been noted when an APP isheld in a melt with a constraint on ammonia loss.

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Thermal analysis studies by the Turin group [55] and by Taylor andSale at Manchester (1992–1993) [59,60] indicate that with release ofammonia and water from APP, the reaction is complex and involvescompeting crosslinking reactions possibly forming P–N–P bonds (P–O–Pbonds should also be considered). In the typical intumescent formula-tion, APP can react with a phosphorylatable substrate such aspentaerythritol and with a reactive amine such as melamine.Melamine can not only be phosphorylated on the NH2 group but canalso form a melaminium salt structure with any phosphorus acid groupor even merely by displacing ammonia from the ammonium structure.Thermal analysis shows that melamine phosphates or polyphosphatesare relatively more stable thermally than APP.

Variations on APP

APP is a complicated material, covering a wide range of molecularweight and having insoluble higher molecular weight versions besidesthe water-soluble, low molecular weight form. A review is available froma leading European manufacturer [61]; in it, X-ray diffraction diagramsare given for five crystal forms, as well as solubility data on the maincommercial high-molecular weight form II and various coated varietiesof form II. A more recent Japanese study [62] also provides X-raydiffraction data on the five forms, and indicates methods of preparation;moreover, the Japanese researchers show that one of the less commonforms (V) may be a better flame retardant than the others, a surprisingresult calling for more research.

Commercial forms of APP are several. A water-soluble, low molecularweight version is used mainly for non-durable cellulosic flame-retardanttextile finishes. A water-insoluble but relatively hydrolysable version,Phase I, is sometimes used in coatings and particularly in applicationswhere water resistance is not needed. A higher molecular weight morewater-resistant Phase II APP is preferred for use in coatings. Severalcoated Phase II APP are available from Clariant, Budenheim, and Asianproducers, with both hydrophilic and hydrophobic coatings. A surface-reacted APP where melamine has been used to replace some of theammonium cations represents another water-resistant grade, and maybe further coated with an amino resin to give a still more water-resistantAPP, at a higher price.

A Hoechst patent [63] claims that APP of degree of polymerization of600–800 and NH4:P mole ratio of about 1 is best in water-based coatingformulations from the standpoint of low solubility in water and gooddispersability with minimal settling.


A Clariant patent [64] claims combinations of APP with melaminepolyphosphate which have improved stability under high humidity(tropical) conditions, suffering less loss of ammonia. This patentdiscloses many diverse formulations with a variety of binders. A similarobject is achieved by including other melamine salts or guanidine saltsas shown in a related Clariant patent [65]. A combination of APP anddicyandiamide phosphate is proposed in a more recent patent [66] as theactive ingredient in a water-based epoxy intumescent coating for wood.

The Thermal Behavior of Melamine Itself

A typical component of intumescent coatings is melamine, which isoften said to be the blowing agent (the ‘spumific’). Actually, the role ofmelamine is complicated, and even the thermal behavior of the materialby itself is complicated, as discussed in our 1995 review [67]. Whenheated in a small amount where vapors can escape without constraint,melamine totally sublimes in the 250–3508C range, as shown by the TGAcurve published by Taylor and Sale [59,60]. However, if the vapors are inany way constrained as, for instance, by heating of melamine from thebottom in a deep layer, part of the melamine sublimes and part losesammonia and goes through a series of ammonia-losing condensations toyield –NH– linked two, three, and multiple ring condensation products,called melam, melem, and melon, respectively. The sublimed melaminevapors and the released ammonia are poor fuels and probably flameinhibitors, even though ammonia gas is per se flammable. Melaminevapor is said to be capable of endothermic dissociation to cyanogens [68],also a poor fuel; whether that chemistry and heat-sink effect play a rolein the flame-retardant contribution of melamine has not beenestablished.

It has been found that in intumescent coatings containing melamine,further addition of a chloroparaffin aids the performance. Lilleresearchers [69] found that melamine or its thermal condensationproducts (discussed in some detail) caused the dehydrochlorination ofthe chloroparaffin and that this was a step in the effective action. It wasfurther suggested that PVA or polyvinyl acetate could be substituted forthe chloroparaffin.

Interaction of Melamine With Phosphorus Ingredients inIntumescent Coatings

Obviously, melamine being a base albeit a rather weak one, can reactwith phosphorus acid species made available, for example, by

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decomposition of ammonium phosphate, or it may even displace someammonia from the ammonium salt to directly make melaminephosphate salts.

Melamine phosphate, pyrophosphate and (later), polyphosphate areall commercially available and they find use in intumescent coatings.A very thorough 1979 review by Kay et al. [70] covers both thecombinations of melamine with phosphate retardants, their interaction,and the use of pre-made melamine phosphates. Our later review(1994) [71] covered the coating applications. Advantages are shownfor melamine pyrophosphate over melamine phosphate in both thermalbarrier formation and lower water solubility. Formulations usingvarious binders are discussed, and details of representative water-based formulations are given using vinyl acrylic emulsion and polyvinylacetate emulsions with performance information. Formulations usingmelamine phosphates and APP together are discussed.

Melamine orthophosphate dehydrates to melamine pyrophosphateand thence at 2908C and above to melamine polyphosphate. Melaminepolyphosphate can serve as both blowing agent and as a substance (or itsthermolysis products) contributing to the foam layer as a coatingintumesces [72]. Further heating under laboratory conditions at above6008C can eventually lead to (PNO)x, a crosslinked solid, although it hasnot been established that this higher temperature chemistry plays asignificant role in intumescent coatings under fire conditions. (PNO)x isprobably too stable and infusible for use as the only phosphoruscomponent in a typical intumescent coating although we found that itmay be effective in systems where it can interact with a polymer such asa polyamide [73].

Variations of Melamine Phosphate

A hybrid salt composition made by the reaction of phosphoric acidwith melamine and monoammonium phosphate is said in a 1993 patent[74] to substantially reduce the solubility of ammonium phosphatewhile retaining its low thermal dissolution (activation) temperature.A number of water-based intumescent paint formulations are shown.

Other Phosphorus Compounds in Intumescent Coatings

Chloroalkyl phosphates and phosphonates have been reported asuseful in intumescent coatings, even coatings which also containinorganic phosphates such as APP; the organic phosphate or phospho-nate esters can provide plasticity, better coating properties, and


can serve as blowing agents and (by breaking down to phosphorusacids) charring catalysts. Some formulations disclosed in patents showuse of monophosphates such as tris(2-chloroethyl) phosphate [63].However, chloroalkyl phosphate and phosphonate oligomers with morethan one phosphorus ester group per molecule such as Phosgard"

C22R or 2XC20 (former Monsanto, now Albemarle) and Fyrol" 99(former Stauffer, Akzo Nobel and Supresta, now ICL-IP) have generallybeen preferred. An early example shows the use of Phosgard" C22Ror 2XC20 in an epoxy-based intumescent coating which also containedAPP and melamine phosphate or guanylurea phosphate [75]. Thispatent, which shows complex formulations, also claims a performanceadvantage of having the decomposition temperatures of two of the activeingredients (either the P or the N component) at least 508C apart.Substantially, halogen-free systems may use triaryl phosphates such asisopropylphenyl diphenyl phosphate (ICL-IP’s Phosflex" 31L or asimilar Chemtura Reofos") to provide plasticity.

Partial esters of polyols, notably of pentaerythritol and glycerol,are made by reaction with polyphosphoric acid and subsequently curedwith epoxy resins and melamine formaldehyde resins to make clearintumescent varnishes on metal, wood, and textiles in a 1995 patent[76]. Further optimization of the coating properties, such as improvedflexibility, is said to be achieved if a partial phosphate polyol ester madefrom tetrahydrofuran or 1,4-butanediol is part of the polyol phosphatereactant [77]. This patent application has a lengthy discussion of thehistory and rationale behind this versatile family of phosphorus-basedintumescent coatings.

Two-component intumescent coatings of the mixed glycerol/pentaer-ythritol acid phosphate type, cured with aminoplast resins, are said to beespecially suited for flame-retardant coating of fiberglass mats [78].

A patent application of Leigh’s Paints [79] discloses the use ofdiglycidyl methylphosphonate, triglycidyl phosphate, bis[2-(methacry-loyloxy)ethyl] phosphate or dihydroxaphosphaphenanthrene oxide(DOPO), or preferably an adduct of DOPO with an epoxynovolac, inintumescent coatings especially for steel.

Char-Producing Ingredients

Many of the older formulations use pentaerythritol as the char former‘carbonific’ in conjunction with APP as the charring catalyst. However,it is somewhat water soluble and the less-soluble although moreexpensive dipentaerythritol is often preferred. In a published compar-ison of pentaerythritol to di- and tripentaerythritol using rheological

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measurements [80], it was found that pentaerythritol was the mosteffective in intumescing sooner and keeping the substrate temperaturedown longer. On the other hand, the temperature at which embrittle-ment started was higher for the di- and tripentaerythritol; so, thisfeature could be of value in lessening the lack of high wind resistanceand the high-temperature cracking – faults of intumescent coatings,especially on cylindrical steel columns.

Lower cost cyclic formals (1,3-dioxanes) which are byproducts ofpentaerythritol manufacture have been shown by Perstorp [81] to beuseful as replacements for the pentaerythritols in intumescent coatings.

Another excellent char former is tris(hydroxyethyl) isocyanurate(THEIC), but this is also water soluble; therefore, polyesters derivedfrom THEIC are shown as preferred by Hoechst in epoxy-basedcoatings [82].

Other ‘carbonific’ (char-forming) additives have been synthesized.A Chinese university group [83] describes preparation and testing ofan ethanolamine–aminotriazine oligomer in a polyurethane intumescentcoating. The formulation had good rheology and the resultant film hadgood thermal stability.

A Polish study [84] was done to arrive at effective intumescentcoatings for wood. In this study, dextrin (a starch product) was part ofthe char-forming system, supplementing a urea–dicyandiamide–formal-dehyde resin catalyzed by APP. Starches, sugars, and cellulose powdersare often mentioned in lists of char-forming ingredients for intumescentformulations.

The Role of Titanium Dioxide in Intumescent Coatings

TiO2 is shown in many intumescent formulations. Besides its use asa white pigment, it is a key reactive in many cases. Commercialintumescent coatings, when fully expanded, often show a white exteriorof the expanded foam, even though the inner part near the substrate isdark carbonized material. This white exterior has been identifiedanalytically [85] as mainly titanium pyrophosphate, formed by thereaction of APP (probably via phosphoric acids) with TiO2. Anotherauthority [86] proposes that titanium pyrophosphate is formed byreaction of P2O5 with TiO2 in the intumescing coating.

An early overview of intumescent fire barriers by a Monsantoresearcher, Ellard [87] emphasized the importance of formation of aglassy outer barrier layer, preferably with a high reflectance, and therole of inorganic oxides (Ti, Zr, and Sb) and phosphates in producingsuch a layer.


Intumescent Silicate Coatings

Water-soluble silicates have a long history of use as wood coatingand impregnants. Because of their water content, and ability tomelt, they tend to be fairly intumescent. They can be produced asintumescent powders and formulated in a binder for use as metal-protective coatings. An improved product of this sort with anintumescent temperature above 1958C, suitable for coatings or firestopsuses a lithium–sodium–potassium silicate composition [88]. Anotherimprovement on the alkali silicate coating is the incorporation of up to5% sodium phosphate which allows for improved high temperatureresistance such as at 9058C as needed in fuel fires [89]. Encouragingresults were obtained with an intumescent inorganic silicate coatingapplied on a glass-reinforced polyester with a glass mat as intermediatelayer; the ASTM E162 test for surface flammability was passed as wellas a US Navy quarter-scale flashover test [90].

An intumescent powder blend was patented by Alcoa [91] comprising afibrous (preferably vitreous) calcium magnesium silicate, used in a coatingor mastic with a binder such as an acrylic resin or polyvinyl acetate.

An intumescent caulk or firestop can be prepared using 3M’sExpantrol" 4BW, a hydrated sodium silicate–borate in a formulationcontaining an acrylate–vinyl acetate–ethylene terpolymer, an organicphosphate plasticizer, zinc borate, a polyol and glass fiber [92].

Patents on Improvements in Intumescent Coatings byBoron-Containing Additives

An early patent [93] on epoxy-based intumescent coatings for wood orsteel beams uses a melamine phosphate combination with melamineborate (optimum 7 : 3) to extend the protective time in a fire.

A fire-protective intumescent coating for steel is claimed [94] using awater-soluble sodium silicate, borax, ATH, and kaolin. Formation of avitreous thermal barrier is shown to occur.

Boric acid is a component of a complex epoxy mastic [95] which alsocontains APP, a triaryl phosphate, THEIC, silica, perlite, and ceramicfibers. This was commercialized as a coating for protection of steel fromhydrocarbon fires.

A French research group [96] showed that including boric acid in anAPP–epoxy-based intumescent coating on steel gave not only longerthermal protection (highest expansion) but also better adhesion andbetter mechanical resistance. Reaction of the boric acid with thephosphate to form a borophosphate was shown [97].

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Zinc borate, or at least a combination of zinc oxide and a borate, isclaimed to improve the thermal protection of steel provided by anintumescent coating which contains the usual APP and melamine, in arather flexible cured epoxy matrix [98]. An overview of the applicationsand performance of these polypropylene glycol (PPG) coatings on steel,particularly for offshore oil platforms, has been published [99].

Patents on Improvements in Intumescent Coatings by OtherInorganic Additives

Intumescent coatings based on the APP–char former–blowing agent–glass fiber combinations are made more protective at high temperaturesby inclusion of Ti or Zr or other metal borides, nitrides, or carbides [100].

Refractory fibers, such as alumina- or silica-based fibers, are added toimprove the high-temperature performance and long duration protectiongiven by a complex intumescent formulation on wood or metal [101].

Intumescent coatings suitable for protecting steel against high-temperature (fuel) fires are enhanced by inclusion of sodium potassiumaluminum silicate (nepheline syenite) or potassium aluminum silicate[102]. Synthetic glasses have been shown to enhance intumescentcoatings [103].

A university study [104] compared a number of commerciallyavailable high-temperature ceramic fibers and some minerals incorpo-rated into an epoxy and a water-based intumescent systems.Carborundum’s Fiberfrax" HS-70C (an alumina–silica fiber with othercomponents) and Zicar" ALBF-1 (an alumina fiber) were found toenhance the toughness of the residual char.

Much effort has been expended on improving fire-resistant coatingsby addition of nanoclays and other nano-dimensional inorganic fillers.A brief review of fire-retardant nanocomposite coatings by Koo andPilato [105] is in a 2006 book. A study on wood-protective intumescentcoatings at the National Institute of Standards joint with Polishresearchers [106] showed that the level of flame-retardant additiveneeded in a butyl acrylate based formulation could be reduced byincorporating some organically modified montmorillonite clay, whilemaintaining fire properties as determined by cone calorimeter. Studiesin China [107] showed that adding up to 1.5% phyllosilicate clay orlayered double hydroxides (both having layers of nanometer thickness)improved the thermal shielding by the char layer. In an overview byTurin Polytechnic investigators [108], nano-scale additives wereproposed (with limited data, mainly on phyllosilicate clays) to give fireprotection benefits in intumescent paints; additives specified were


montmorillonite, hectorite, saponite, double-layer MgAl hydroxides,zirconium phosphate, carbon nanotubes, nanosilica, nanotitania,nanoalumina, fullerenes, and silsesquioxanes. Exfoliated montmorillo-nite clay was shown by Hu and Koo [109] to have a synergistic effect in aconventional intumescent wood coating.

Chinese studies [110] showed that about 4% of nanometer silica ormagnesium hydroxide, surface modified by Solsperse" 17000, canimprove the water resistance of APP–pentaerythritol–melamine coat-ings without harming flame retardancy.

Catalysts to Improve Intumescent Formulations

The addition of certain spirobis amines (example: 2,4,8,10-tetraox-aspiro-5,5-undecane-3,9-dipropamine) and quaternary phase transfercatalysts (example: tetrabutylammonium salts) are shown to improvethe performance of intumescent systems based on APP, melaminephosphate or ethylenediamine phosphate [111]. The working examplesare in non-coating systems.

Patents on Expandable Graphite in Intumescent Coatings

Citations in recent patents provide a history of the use ofheat-expandable acid-treated graphite flakes to boost the fire-barrierproperties of various types of intumescent coatings. A representativepatent by Huber inventors shows use of expandable graphite plus anacid-capturing additive such as calcium carbonate to enhance a typicalintumescent system for wood [112]. The combined use of expandablegraphite with glass or ceramic microballoons is shown in an otherwise-typical intumescent coating for building components such as steelconduits [113]. Another Avtec patent [114] shows use of expandablegraphite together with a cement and a ceramic in a smoke- and fire-resistant coating with typical intumescent components. The use ofexpandable graphite in an acid-hardenable resin coating is shown for useon oriented strand board, fiberboard or glass-reinforced sandwich panelsin a Georgia-Pacific Resins patent (2001) [115].

Binders for Intumescent Coatings

A variety of polymeric binders have been used. In water-basedintumescent coatings, a polyvinyl acetate emulsion is often chosen, andit is believed to also contribute to the char.

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In a comparison of various binders for a conventional APP–melamine–pentaerythritol formulation, chlorinated rubber blended with chloro-paraffin gave high performance and withstood aging [116]. The useof a low modulus rubber with a similar intumescent formulation forsteel coating has been claimed in a patent disclosure by Britishinventors [117].

In an Eliokem patent application [118], it is shown that a combina-tion of a linear and a crosslinked (reticulated) methylstyrene–acrylic copolymer not only reduces flame spread in the early stagesof a fire but also improves the char formation and insulatingproperties of the char in the later stages of a fire. Eliokem researchers[119] have discussed the systematic development of optimizedsubstituted styrene–acrylate latexes for fire-resistant coatings.Better water resistance compared to vinyl acetate copolymers isshown. A study at Eliokem indicated optimum thermal stabilityof protective coatings for metals by combining 2-ethylhexyl acrylate-p-methylstyrene linear and reticulate copolymers [120,121]. TheEliokem styrene (or vinyltoluene)–acrylate copolymer resins, sold asPliolites", are used in Leighs Paints solvent-based intumescent coatingson steel, for example protecting the large steel structure of theWimbledon tennis courts (2009 report). Studies at Eliokem haveelucidated the relative efficiency of various thin film intumescentcoatings [122].

A polymerizable resin approach is shown in a W. & J.Leigh patent [123] which discloses a classical APP–pentaerythritol–melamine intumescent formulation with a polymerizable acrylicresin plus preferably a preformed meth(acrylate) polymer plus afree-radical polymerization initiator such as benzoyl peroxide.This provides a liquid formulation which cures to a solid on asubstrate such as steel. A related patent [124] uses a similar liquidcomposition with a reinforcement structure such as fiberglass or steelmesh.

Solid intumescent formulations suitable for powder coatingsare described in a Leigh patent [125] and a wide variety of thermoplasticand thermosetting binders, including polyethylene, are said to be usefulbut the working examples use a thermoplastic polyetheramine,Dow Blox" 2100.

Improvement in adhesion of intumescent coatings to metal is claimedto result from including in an acrylic binder formulation a copolymeriz-able acid monomer, namely, an acid (meth)acrylate, maleic, fumaric, oritaconic acid [126].


Epoxy-Based Intumescent Coatings and Mastics forSteel Protection

Present-day formulations can be rather complex, particularly thoseused for their intumescent thick coatings (mastic) such as employed forprotection of off-shore oil drilling platforms and petrochemicalinstallations.

Examples of such advanced and proprietary formulations are Textron’s(now Akzo Nobel’s) Chartek" and PPG’s Pittchar". An exampleof a Pittchar" formulation is disclosed in a PPG patent [127]. Theformulation is as follows (component; parts by weight): Package 1:diglycidyl ether of bisphenol-A, 35.77; melamine, 2.75; APP, 4.52; tall oilfatty acid, 4.27; tris(2-chloroethyl) phosphate, 8.79; attapulgite gellant,3.31; boric acid 20.64; zinc borate, 7.87; wollastonite, 12.05. Package 2:Versamid" 150 curing agent, 72.25; Aerosil" vapor-phase-producedsilica, 3.50; Iimsil" A-10 silica, 13.72; attapulgite gellant, 4.50; talc, 6.00.Packages 1 and 2 are mixed in 1.65 weight ratio before applying. Thiscoating is applied in a thick layer as a mastic. A more flexible epoxycoating with many of the same ingredients but with a polyester-chain-extended epoxy has been described in later PPG patents [128,129].

An interesting intumescent coating for steel has recently beenpatented and probably commercialized by Chance & Hunt Ltd andFerro Ltd [130], wherein a combination of an epoxy resin with analdehyde resin or ketone thermoplastic resin serving as part of thebinder and as the ‘carbonific’ (char-forming) component. The formula-tion is: 18% epoxy resin, 6% phenolic curing agent, 10% ketone resin(such as BASF’s Laropal" A81), 3.5% % hydrogenated castor oil viscositymodifier (such as Rheox’s Thixcin"), 55% APP (such as Exolit" 422),and 7.5% TiO2.

A low-density epoxy-based intumescent coating, Chartek" VII, isdescribed in a Textron patent [131]. The composition, which must bemixed in a very specific sequence and manner, is quite complex, aspresented in Table 1. Each of the two parts is mixed before applying:by spray equipment

The density of this coating can be further reduced by pressurizing anddispersing a gas in it before applying. This recipe suggests thatsophisticated formulation development is needed to achieve competitiveproducts in the flame-retardant coatings field.

Recent intumescent coatings with lengthened fire resistance havemade use of the very active dialkylphosphinate aluminum salt as partof the flame-retardant composition [132]. A representative formulationused 25 parts of boric acid, 9 parts of THEIC, 2 parts of TiO2, and 5 parts

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of a mixture of APP and aluminum diethylphosphinate (Exolit"

OP1230) in 100 parts of epoxy resin (Beckopox" EP140) cured withan aliphatic polyamine. Cured on steel at 3.5 mm, this coating gave44 min of fire resistance.

Special Applications of Intumescent Coatings

Multi-layered structures can be used to give a high degree of fireprotection to steel structural elements; one patent [133] indicates thatan outer layer can be fiberglass with an intumescent coating, on top of areflective metal foil, on top of a low conductivity refractory-fiber blanket,on top of another reflective metal foil layer. A similar multi-layerconstruction can be used to protect conduits and cables [134]. The NoFire technology also has found application in passenger aircraft.

The multi-layer concept was applied differently in a patent to Battelleinventors [135]. Here, the idea is to apply a first intumescent coatinglayer on the substrate, then on top of that, another intumescent coatingwhich forms a less dense layer of foam when exposed to fire, the outer

Table 1. Intumescent low-density epoxy coating (mastic) formulation.

Ingredient Weight (lbs)

Part AEpoxy resin (Dow DER 331) 1702.8Triaryl phosphate 438.3Black pigment 4.5Antifoaming siloxane surfactant 0.45Amorphous hydrophobic fumed silica 67.5Fire-retardant mix (64% APP (Exolit

"422) and 36% THEIC) 675

Boric acid 1521.4Expanded perlite 45Amorphous mineral fiber (Inorphil

") 22.5

High-surface area Al2O3/SiO2 fiber (HSA fiber, Unifrax") 22.5

Part BAmidoamine curing agent 2554Wetting agent 10Antifoaming surfactant 0.4Milled limestone 401.2Fire-retardant mix (64% APP (Exolit

"422) and 36% THEIC) 461.6

Rutile TiO2 pigment 76.8Perlite 224Amorphous mineral fiber (Inorphil

") 148.4

High-surface area Al2O3/SiO2 fiber (HSA fiber, Unifrax") 123.6


layer giving the immediate fire protection and the inner harder layerproviding a second layer of defense in case breakthrough of the outerintumesced layer occurs. The outer layer formulation is based on APP,dipentaerythritol, and epoxy with an azobiscarbonamide blowing agent.

The use of intumescent coatings on plastics, such as plastic pipe, isdisclosed in a Monsanto Europe patent [136]. These coatings, however,are not paints or mastics but appear to be extruded or laminated, andhave a substantial thermoplastic, possibly foamed thermoplastic,content.

Thin intumescent coatings on wire and cable, applied by meltextrusion, are described in a patent application of Reyes [137] usingformulations in a polyolefin including melamine phosphate, ethylene-diamine phosphate, and activators of the pentaerythritol spirobisacetal,and quaternary ammonium types as mentioned earlier in connectionwith a Rhodes et al. [111] patent.

Polyurethane foams used in thermal insulation can be made fire-resistant by an intumescent coating, preferably applied by spraying, asdescribed in a patent application [138]. Another coating for the samepurpose is a water-based Flame Seal"-TB Spray-Applied ThermalBarrier from Specialty Products, Inc. [139]. Further foamed coatingsapplicable to thermal insulation for fire, sound, and heat barrierspurposed are described by Lanxess [140].

Patented combinations of intumescent paints (such as based on APP,pentaerythritol and melamine, and latex binder) with mold inhibitorsand insecticides (particularly termiticides) have been disclosed[141,142]. These may be applied to any substrate for fire, mold, andinsect (termite) protection.

Intumescent Coatings on Textiles

These coatings are usually applied to the surface as a layer. Productsfrom Thor (France) used in this way are Aflamman" PCS andAflamman" IST (water-soluble organic–inorganic phosphorus nitrogencombination), applied with a polyvinyl acetate emulsion binderRhenappret" RA. A French study shows that this finish on polyesterfabric lengthens the time to ignition and shortens the time to extinction,and can provide a French M1 (non-flammable) rating [143].

Improved fire-protective performance on substrates such as, particu-larly, textiles is claimed for intumescent coating formulations containingAPP, pentaerythritol, and melamine with specific latex polymers(styrene–acrylate–methylenebisacrylamide copolymers exemplified)having a thermogravimetric weight loss of at least 7% at 3708C [144].

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Improved thermal and warm water resistance properties of coatedtextiles such as car interior fabrics are said to be achieved by use, inplace of APP, of a melamine phosphate coated with a functionalorganosilicon resin [145]. An extensive university study of phosphorus-containing flame retardants in backcoating of textiles was conducted inthe UK [146]. These formulations are not necessarily intumescent ones.

Silicone Coatings

Silicone coatings with dispersed carbon nanotubes have beenintroduced as Nanocyl’s ThermoCyl" to give fire protection to a widevariety of substrates, such as plastics, cables, textiles, foams, metals, andwood [147]. Coatings as thin as 100mm have been shown effective. Thesedo not appear to be intumescent coatings.

Very High-Temperature Ceramic Coatings

Coatings such as Al2O3–TiO2, ZrO2, and other ceramic thermalbarrier coatings are used, for example in aerospace, electronic andbiomedical applications, and may be applied usually to metal substratesby plasma/high-velocity oxygen flame spraying. Further discussion isoutside the scope of this review and the reader is directed to the annualproceedings of the International Thermal Spray Conference. Slurrymethods of application of ceramic coatings are also used to providemetals with short-term exposure to high temperatures, and have beenreviewed [148].

Aerospace tiles, which are inherently fire resistant, can be coated withfurther heat-resistant coatings such as a recently disclosed system ofceramic/metal nanoparticles [149].

Ceramicizable compositions, suitable for cable coatings and seals,have been developed by an Australian group [150] on the basis of asilicone polymer, mica, and a combination of a low melting glass and ahigh melting glass. These inorganic materials flux to form a self-supporting protective ceramic coating after the organic component hasburned away. The same research group discloses a related ceramifyingcoating material, suitable for protecting cables at high temperature,using an inorganic phosphate, which is exemplified by APP, as part ofthe ceramifying system along with a mineral silicate exemplified by talc,mica, or clay [151]. A discussion of the science and technology of thisapproach has been published by the Australian researchers [152].

Australian researchers [153] described a basic study which led toceramifying compositions based on polyvinyl acetate, kaolin or talc,


magnesium hydroxide, and zinc borate (as flux). Kaolin providedstronger ceramic but talc provided a better thermal barrier for firestopapplications.

Intumescent Coatings on Reinforced Thermoset Composites

An extensive study of intumescent coatings for shipboard use, usingsmall-scale and full-scale fire, adhesion and impact tests, by the US Navy[154] showed failure to meet Navy criteria when used as stand-alonecoatings on reinforced thermoset composites. Many of the coatingsdemonstrated poor adhesion during fire tests. However, some did reduceflame spread and smoke generation when applied over reinforced plastic,and one which contained a mineral adjuvant performed well incombination with StructoGard" (a mineral blanket).

Testing of Fire-Protection Coatings

A succinct review of tests for fire-protective coatings, especially forsteel, is found in a 2002 BCC paper [155].

Typical large-scale tests in the USA are the ASTM E-84 (Steinertunnel) for flame spread and the ASTM E119 for fire resistance. Thereare also UL 1709 or ASTM E1529 for protection time in a rapidtemperature rise fire, such as the one which may occur in an offshore oilor gas platform. Both UL 1709 and ASTM E1529 require a test furnacewhich develops an average temperature of 20008F (10938C) in the first5 min. The principal difference is that the UL 1709 involves a total heatflux somewhat larger than that in ASTM E1529. These are all quitelarge tests with specially dedicated equipment. The test method, ASTME119 (also UL 263 and the similar ISO 834 used elsewhere in the world),involves a large test rig, has been used for decades and is still used tomeasure the fire performance in a solid fuel fire (‘cellulosic’ type fire), ofwalls, doors and floors. For combustible construction materials such aswood, the ASTM E-84 is commonly used to measure the effectiveness ofcoatings to retard flame spread. However, this test requires largesamples and is relatively costly. A useful ability to predict E-84 resultson coated wood was demonstrated using small-scale tests in the conecalorimeter Koo’s group [156].

Standards and tests relating to civilian shipboard fire protection areunder the SOLAS Codes of the International Maritime Organization andin the USA, administered by the Coast Guard. An overview of thestandards going into effect in 2003, and systems for meeting thesestandards, was presented in 2002 [157].

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From a research standpoint, a faster and convenient small-scalescreening test was developed at Lille [158]. This test involves using asmall radiant heater (the French epiradiateur, directed downward on a5! 5 cm2 plate painted with the test coating. An infrared thermometer isused to read the bottom temperature of the plate. Even more informaltests of this sort are sometimes run for purposes of formulationdevelopment, using a propane torch held at a fixed distance from thecoated plate.

British standards for fire-protective coatings are discussed andillustrated in a 1983 review which covers in special detail the railwayrequirements and experience [159]. A major standard for fire protectionof building materials has been BS 476, part 21. This has been replacedby the CEN standards of the European Union and the related ISO 834standard elsewhere.

Firestops

In a building, penetrations through fire-rated walls and floors/ceilingsfor pipes, ducts, cables, wires, conduits, and structural membersprovide dangerous pathways for fires and fire gases to spread.In recent years, building officials and fire marshals have begun toprioritize firestopping barriers in building codes. In the USA, fire-stopping should use products tested and approved under ASTM E 814,a test with a specified flame at one side of the aperture, and meansfor measuring temperature on the other side. Time for no passageand time to reach 400F are measured, as well as air leakage. Resistanceto a hose stream is also evaluated.

Much of the patent literature on firestops emphasizes the mechanicalaspects such as shaping to fit various apertures, the use of shields andsupports, putty-like materials, and combinations with aperture blockingmeans such as mineral wool. We will cite some representative patents ofleading firestop manufacturers which emphasize the compositionalaspects, often complex, and often proprietary.

A flexible felt containing an intumescent material was patented by3M [160], the composition comprising an acrylic latex, a phosphateplasticizer, an APP, an acid-treated expandable graphite, ATH, sodiumaluminate, aluminum sulfate, and various surfactants applied to a mixof ceramic fibers and rayon fibers, and compressed to a fire-barrier felt.

A more recent solid fire sealing material patented by 3M [161]comprises a dried rubber latex, TiO2, APP, a phosphate plasticizer, 3M’sExpantrol" (a granulated hydrated sodium silicate), and variousstabilizers. A firestop putty, also patented by 3M [162] contains a mix


of rubbers, epoxy resin powder, silica, melamine, boron oxide, fiberglass,a liquid olefin copolymer, and Expantrol" or expandable graphite.

A version of expandable graphite said to be advantageous as a firestopingredient because of reduced onset temperature and higher expansionis patented by Hilti [163] and it uses nitroalkane and ferric chloride forintercalation of the graphite. Another Hilti patent [164] describes acomplex formulation for a two-component intumescing foam comprisingspecific polyurethane foam-forming ingredients, APP, tris(chloroisopro-pyl) phosphate, dipentaerythritol, melamine cyanurate, zinc borate, ironoxide, silica, expandable graphite, and urethane catalysts; this formula-tion is injectable into wall apertures as a firestop.

Flexible intumescent sheets, suitable for firestops in the gap betweendoor and doorframe, were patented by Rectorseal [165] which compriseexpandable graphite, ethylenediamine phosphate (an intumescing salt),and a soft emulsion resin.

A two-stage expandable firestop was patented by SpecifiedTechnologies [166] which makes use of a two-stage expansion: thelower temperature expansion uses microcapsules with polyvinylidenechloride walls filled with liquid isobutene and the higher temperatureexpansion uses expandable graphite, both in an acrylic latex. A relatedfirestop system [167] uses expandable graphite plus alkane-filledmicrocapsules (Akzo-Nobel Expancel") or a nitrogen- or CO2-releasingblowing agent, plus, as a supplemental flame retardant, a phosphate,borate, or clay.

FLAME-RETARDANT GELCOATS

These are coatings made from curable unsaturated polyester resinsand cured in place, typically onto a glass-reinforced polyester laminate.They are often in the range 0.4–0.5 mm, and provide a smooth surface tothe laminate. Unlike paints, they may be applied as an early stage oflaminate production, such as in the mold. Typical formulations aresimilar to regular unsaturated polyester resins, and with similar curingcatalysts (usually peroxides) but with thixotropic agents added tocontrol rheology. Flame retardancy requirements for gelcoated compo-sites are often found in railway, construction, and marine applications.A new railway requirement in Europe is the EN 45545 standard whichinvolves a flame spread test, as discussed in a recent Cytec paper [168].Intumescent formulations such as based on APP, pentaerythritol andmelamine may be used. ATH may also be used but high loadings haveviscosity problems. A UK article [169] discusses the trade-off between

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weatherability and flame spread, and the choice of putting the flameretardant in the gelcoat or in the base laminate. A recent article fromClariant [170] shows that the British rail standard 476 can be passed byusing 50 phr of Exolit" AP 740 (an APP plus a char former) in a gelcoatplus 50 phr ATH in the laminate or 100 phr Exolit" AP 740 in thegelcoat and none in the laminate. This second option is especially usefulfor the resin transfer molding process.

CONCLUSIONS AND FUTURE DEVELOPMENTS

Effective products have evolved to meet fire protection requirementson steel, wood, and to some extent on plastic or elastomer substrates.Depending on composition and thickness, protection can be offeredagainst both lower energy ‘cellulosic’ fires and high-energy ‘hydro-carbon’ fires.

Demanding new standards for fire testing, test standardization, andproduct classification, such as ENV 13381 and EN 13501 may drive thedevelopment of improved intumescent and other types of fire-protectivecoatings, predicted by European coatings workers [171]. In the USA,wider adoption of the ICC building codes continues, and some of therequirements can be met most economically by fire-resistant coatings.Environmental considerations, particularly strict solvent limitations tolimit air pollution, strongly favor water-based or high-solid coatings.

Some shortcomings still need to be met by further research anddevelopment. Weathering of exterior intumescent coatings has usuallybeen inadequate because of hydrophilic components. Protective topcoatings can be used, but add to cost. A recent patent application claimsthat the inclusion of a highly water-resistant resin component,exemplified by a polyvinylidene fluoride emulsion such as Arkema’sKynar" Aquatec, in an otherwise typically hydrophilic intumescentformulation improves water resistance [172] and may avoid the need fora protective topcoat.

Adhesion of fire-resistive coatings to substrates, particularly steel,may require a primer coat, but this also may be avoidable by self-primingformulations. Adhesion to plastic or elastomer surfaces presents anR&D opportunity. Single coating applications have obvious costadvantages.

A shortcoming of some protective intumescent coatings on steelcolumns is the tendency to crack open at the full extent of theirexpansion, thus exposing the substrate to the flames. A recent patentapplication by a Japanese company (2010) [173] indicates an


APP–pentaerythritol–melamine formulation in which the crackingpropensity has been controlled by including rockwool fibers.

REFERENCES

1. Weil, E. and Levchik, S. (2009). Flame Retardants for Plastics and Textiles:Practical Applications, Hanser Publishers, Munich/Cincinnati, OH.

2. White, R.H. and Dietenberger, M.A. (2010). Fire Safety of WoodConstruction, In: Wood Handbook, Chapter 18, pp. 18–1ff, ForestProducts Laboratory, US Department of Agriculture, Madison, WI.General Technical Report FPL-GTR-190.

3. Heemstra, D. (2009). Intumescent Fireproof Coatings: Their Uses andApplications. Available at: http://www.corrdefense.org/Academia%20Government%20and%20Industry/T-01.pdf (accessed date December 28, 2010).

4. Vandersall, H.L. (1971). Intumescent Coating Systems, Their Developmentand Chemistry, Journal of Fire and Flammability, 2: 97–140.

5. Weil, E.D. and Levchik, S.V. (2008). Flame Retardants in Commercial Useor Development, Journal of Fire Sciences, 26: 5–43.

6. Schwarz, R. (2003). Coatings that can Save Lives, Coatings World,Nov. 2003: 54–59.

7. Allen, C. (1999). Choosing the Right Fireproofing for Structures andEquipment Supports, Chemical Engineering Progress, 95: 75–80.

8. Goode, M., ed. (2004). Fire Protection of Structural Steel in High-RiseBuildings, GCR 04-872, Building and Fire Research Laboratory, NIST,Gaithersburg, MD.

9. Challener, C. (2007). Fire Safety with Specialty Coatings, JCT CoatingsTech, Sep. 2007: 78–84.

10. Green, J. (2005). Fire-Retardant/Fire-Resistive Coatings, In: Tracton, A.(ed.), Coating Technology Handbook, 3rd edn, pp. 773–778, CRC Press,Boca Raton, FL.

11. Dahm, D.B. (1996). Reformulation of Fire Retardant Coatings, Progress inOrganic Coatings, 29: 61–71.

12. www.nstcenter.com/milspecs.aspx?milspec¼24647 (accessed date December28, 2010).

13. Calbo, L., ed. (1992). Handbook of Coatings Additives, Vol. 2, p. 261, MarcelDekker, Inc., New York, NY.

14. Spain, R. (1987). US Patent No. 4,666,960.

15. Kruse, D., Simon, S., Menke, K., Friebel, S. and Gettwert, V.(to Fraunhofer–Gesellschaft zur Fordering der angewandten Forschung)(2005). German Patent Application No. 10 2004 023 166.

16. Ray, N., Shaw, B. and Lane, B. (to Imperial Chemical Industries) (1976). USPatent No. 3,933,689.

17. Anon. CEEPREE. Available at: http://www.chance-hunt.com/ceepree/product.htm (accessed date December 28, 2010).

286 E. D. WEIL

18. Lin, S.-C. and Kent, B. (2009). Flammability of Fluoropolymers, In: Wilkie,C., Morgan, A. and Nelson, G. (eds), Fire and Polymers V: Materials andConcepts for Fire Retardancy, ACS Symposium Series 1013, pp. 294–295,American Chemical Society, Washington, DC.

19. Duquesne, S., Jimenez, M. and Bourbigot, S. (2009). Fire Retardancy andFire Protection of Materials Using Intumescent Coatings – A VersatileSolution? In: Hull, R. and Kandola, B. (eds), Fire Retardancy of Polymers:New Strategies and Mechanisms (FRPM ‘07), 11th, Bolton, UK, 4–6 July,2007 (published in 2009 by Royal Society of Chemistry, Cambridge, UK),pp. 240–252.

20. Cagliostro, D.E., Riccitiello, S.R., Clark, K.J. and Shimizu, A.B. (1975).Intumescent Coating Modeling, Journal of Fire and Flammability,6: 205–221.

21. Anderson, Jr, C.E., Dziuk Jr, J., Mallow, W.A. and Buckmaster, J.(1985). Intumescent Reaction Mechanisms, Journal of Fire Sciences,3: 161–194.

22. Buckmaster, J., Anderson, C. and Nachman, A. (1986). A Modelfor Intumescent Paints, International Journal of Engineering Science,24: 263–276.

23. Shih, Y.C., Cheung, F.B. and Koo, J.H. (1998). Theoretical Modelingof Intumescent Fire-Retardant Materials, Journal of Fire Sciences, 16: 46–71.

24. Mamleev, V.Sh., Bekturov, E.A. and Gibov, K.M. (1998). Dynamics ofIntumescence of Fire-Retardant Polymeric Materials, Journal of AppliedPolymer Science, 70: 1523–1542.

25. Reshetnikov, I.S., Yablokova, M.Yu. and Khalturinskij, N.A. (1998).Physical Aspects of Intumescence, Recent Advances in Flame Retardancyof Polymeric Materials, Business Communications Co. Norwalk, CT, 1998,Vol. 9, pp. 300–302.

26. Antonov, A.V., Reshetnikov, I.S. and Khalturinskij, N.A. (1999).Combustion of Char-Forming Polymeric Systems, Russian ChemicalReviews, 68: 605–614 (in English).

27. Reshetnikov, I.S., Yablokova, M.Yu. and Khalturinskij, N.A. (1997).Influence of Surface Structure on Thermoprotection Properties ofIntumescent Systems, Applied Surface Science, 115: 199–201.

28. Koo, J. (1997). Thermal Characteristics Comparison of Two Fire ResistantMaterials, Journal of Fire Sciences, 15(3): 203–221.

29. Bhargava, A. and Griffin, G. (1999). A Two-Dimensional Model of HeatTransfer Across a Fire Retardant Epoxy Coating Subjected to an ImpingingFlame, Journal of Fire Sciences, 17(3): 188–208.

30. Bhargava, A. and Griffin, G. (2003). Kinetics of Degradation ReactionsWithin Intumescent and Subliming Fire Retardant Coatings, Journal ofFire Sciences, 21(3): 173–188.

31. Griffin, G., Bicknell, A. and Brown, T. (2005). Study of the Effectof Atmospheric Oxygen Content on the Thermal Resistance of IntumescentFire-Retardant Coatings, Journal of Fire Sciences, 23(4): 303–328.

32. Lautenberger, C. and Fernandez-Pello, C. (2009). GeneralizedPyrolysis Model for Combustible Solids, Fire Safety Journal, 44(6): 819–839.


33. Bourbigot, S., Duquesne, S. and Leroy, J.-M. (1999). Modeling of HeatTransfer of a Polypropylene-Based Intumescent System DuringCombustion, Journal of Fire Science, 17(1): 42–56.

34. Bourbigot, S., Jimenez, M. and Duquesne, S. (2006). Modeling Heat BarrierEfficiency of Flame Retarded Materials, In: Petit, J.M. and Squalli, O. (eds),Comsol Multiphysics Conference 2006, Comsol France, Paris, 2006, pp. 59–65.

35. Jimenez, M., Duquesne, S. and Bourbigot, S. (2006). Intumescent FireProtective Coating: Toward a Better Understanding of Their Mechanism ofAction, Thermochimica Acta, 449: 16–26.

36. Gillet, M., Autrique, L. and Perez, L. (2007). Mathematical Model forIntumescent Coating Growth: Application to Fire Retardant Systems,Journal of Physics D: Applied Physics, 40: 883–899.

37. Dai, X.H., Wang, Y.C. and Bailey, C.G. (2009). Effects of Partial FireProtection on Temperature Development in Steel Joints Protected byIntumescent Coating, Fire Safety Journal, 44: 376–386.

38. Branca, C., Di Blasi, C. and Horacek, H. (2002). Analysis of the CombustionKinetics and Thermal Behavior of an Intumescent System, Industrial andEngineering Chemistry Research, 41(9): 2107–2114.

39. Reshetnikov, I.S., Antonov, A., Rudakova, T., Aleksjuk, G. andKhalturinskij, N.A. (1996). Some Aspects of Intumescent Fire RetardantSystems, Polymer Degradation and Stability, 54: 137–141.

40. Horacek, H. (2009). Reactions of Stoichiometric Intumescent Paints,Journal of Applied Polymer Science, 113: 1745–1756.

41. Reshetnikov, I., Garashchenko, A. and Strakhov, V. (2000). ExperimentalInvestigation into Mechanical Destruction of Intumescent Chars, Polymersfor Advanced Technologies, 11(8–12): 392–397.

42. Reshetnikov, I.S., Yablokova, M.Yu., Potapova, E., Khalturinskij, N.A.,Chernyh, V.Y. and Mashlyakovskii, L.N. (1998). Mechanical Stabilityof Intumescent Chars, Journal of Applied Polymer Science, 67: 1827–1830.

43. Berlin, A.A., Khalturinskij, N.A., Reshetnikov, I.S. and Yablokova, M.Yu.(1998). Some Aspects of Mechanical Stability of Intumescent Chars,In: Le Bras, M., Camino, G., Bourbigot, S. and Delobel, R. (eds), FireRetardancy of Polymers: The Use of Intumescence, pp. 104–112, RoyalSociety of Chemistry, Cambridge, UK.

44. Reshetnikov, I.S., Yablokova, M.Yu. and Khalturinskij, N.A. (1998). SpecialFeatures of Bubble Formation During Intumescent Systems Burning,In: Le Bras, M., Camino, G., Bourbigot, S. and Delobel, R. (eds), FireRetardancy of Polymers: The Use of Intumescence, pp. 140–151, RoyalSociety of Chemistry, Cambridge, UK.

45. Reshetnikov, I.S. and Khalturinskij, N.A. (1998). The Role of Radiation overIntumescent Systems Burning, In: Le Bras, M., Camino, G., Bourbigot, S.and Delobel, R. (eds), Fire Retardancy of Polymers: The Use of Intumescence,pp. 152–158, Royal Society of Chemistry, Cambridge, UK.

46. Jimenez, M., Duquesne, S. and Bourbigot, S. (2006). MultiscaleExperimental Approach for Developing High-PerformanceIntumescent Coatings, Industrial and Engineering Chemistry Research,45: 4500–4508.

288 E. D. WEIL

47. Jimenez, M., Duquesne, S. and Bourbigot, S. (2009). Kinetic Analysis of theThermal Degradation of an Epoxy-Based Intumescent Coating, PolymerDegradation and Stability, 94(3): 404–409.

48. Bourbigot, S. and Le Bras, M. (1998). Synergy in Intumescence: Overviewof the Use of Zeolites, In: Le Bras, M., Camino, G., Bourbigot, S. andDelobel, R. (eds), Fire Retardancy of Polymers: The Use of Intumescence,pp. 222–234, Royal Society of Chemistry, Cambridge, UK.

49. Le Bras, M., Bourbigot, S., Siat, C. and Delobel, R. (1998). ComprehensiveStudy of Protection of Polymers by Intumescence – Application to EthyleneVinyl Acetate Copolymer Formulations, In: Le Bras, M., Camino, G.,Bourbigot, S. and Delobel, R. (eds), Fire Retardancy of Polymers: The Useof Intumescence, pp. 266–278, Royal Society of Chemistry, Cambridge, UK.

50. Bertelli, G., Marchetti, E., Camino, G., Costa, L. and Locatelli, R. (1989).Intumescent Fire Retardant Systems: Effect of Fillers on Char Structure,Angewandte Makromolekulare Chemie, 172(2868): 153–163.

51. Scharf, D., Nalepa, R., Heflin, R. and Wusu, T. (1992). Studies on FlameRetardant Intumescent Char, Fire Safety Journal, 19: 103–117.

52. Kozlowski, R., Wesolek, D. and Wladyka-Przybylak (to Instytut WlokienNaturalnych) (2009). US Patent Application No. 2009/0215926.

53. Series of articles mainly in Polymer Degradation and Stability summarizedand referenced in Camino, G. and Luda, M.P. (1998). Mechanistic Studyon Intumescence, In: Le Bras, M., Camino, G., Bourbigot, S. and Delobel, R.(eds), Fire Retardancy of Polymers: The Use of Intumescence, pp. 48–63,Royal Society of Chemistry, Cambridge, UK.

54. Bourbigot, M., Le Bras., M., Duquesne, S. and Rochery, M. (2004). RecentAdvances for Intumescent Polymers, Macromolecular Science andEngineering, 289(6): 499–511.

55. Camino, G., Costa, L. and Trossarelli, L. (1985). Study of theMechanism of Intumescence in Fire Retardant Polymers: Part V –Mechanism of Formation of Gaseous Products in the ThermalDegradation of Ammonium Polyphosphate, Polymer Degradation andStability, 12: 203–211.

56. Marchand, R., Boukbir, L., Falchier, P., Laurent, Y., Bonnaud, O. and Roult,G. (1988). L’Oxynitrure de Phosphore Massif PON, Le Vide, les CouchesMinces, 241: 231–232.

57. Boukbir, L., Marchand, R., Laurent, Y., Bacher, P. and Roult, G. (1989).Preparation and Time-of-flight Neutron Diffraction Study of theCristobalite-type PON Phosphorus Oxynitride, Annales de Chimie, 14(8):475–481.

58. Marchand, R., Laurent, Y. and Favennec, P. (to Centre Nationale de laRecherche Scientifique et Etat Francaise repr. par Ministre des PTT).French Patent Application No. 2,617,152 (30 December, 1988).

59. Taylor, A.P. and Sale, F.R. (1992). Thermal Analysis of IntumescentCoatings, Polymers Paint Colours Journal, 182(4301): 1222–1225.

60. Taylor, A.P. and Sale, F.R. (1993). Thermoanalytical Studies ofIntumescent Systems, Macromolecular Chemistry, MacromolecularSymposia, 74: 85–93.


61. Futterer, T. (2006). Ammonium Polyphosphates, Special ChemicalsMagazine, July–August 2006: 34–36.

62. Watanabe, M., Sakurai, M. and Maeda, M. (2009). Preparation ofAmmonium Polyphosphate and Its Application to Flame Retardant,Phosphorus Research Bulletin, 23: 35–44.

63. Dany, F.-J., Wortmann, J. and Kandler, J. (to Hoechst) (1977). US PatentNo. 4,009,137.

64. Pirig, W.-D. and Thewes, V. (to Clariant) (2001). US Patent No. 6,251,961.

65. Pirig, W.-D., Rothkamp, S. and Thewes, V. (to Clariant) (2000). US PatentNo. 6,054,513.

66. Ward, D. (to Intumescent Systems Ltd) (2009). European PatentApplication No. 2,093,263.

67. Weil, E. and Choudhary, V. (1995). Flame Retarding Plastics andElastomers with Melamine, Journal of Fire Science, 13(2): 104–126.

68. Mackay, J.S. (to American Cyanamid Co.) (1951). US Patent No. 2,566,231.

69. Ducrocq, P., Duquesne, S., Magnet, S., Bourbigot, S. and Delobel, R. (2006).Interactions Between Chlorinated Paraffins and Melamine in IntumescentPaint – Inventing a Way to Suppress Chlorinated Paraffins from theFormulations, Progress in Organic Coating, 57(4): 430–438.

70. Kay, M., Price, A. and Lavery, I. (1979). A Review of Intumescent Materials,With Emphasis on Melamine Formulations, Journal of Fire RetardantChemistry, 6: 69–90.

71. Weil, E. and McSwigan, B. (1994). Melamine Phosphates andPyrophosphates in Flame Retardant Coatings: Old Products with NewPotential, Journal of Coatings Technology, 66(839): 75–82.

72. Thewes, V. and Pirig, W.-D. (to Clariant GmbH) (2001). US PatentApplication No. 2001/0027226.

73. Levchik, S., Levchik, G., Balabanovich, A., Weil, E. and Klatt, M. (1999).Phosphorus Oxynitride. A Thermally Stable Fire-Retardant Additive forPolyamide 6 and Polybutylene Terephthalate, AngewandteMakromolekulare Chemie, 264: 48–55.

74. Hill, Jr J., (to Material Technologies & Sciences) (1993). US Patent No.5,225,464.

75. Caltop SA (assignee) (1980). British Patent No. 1,575,708.

76. Aslin, C. (to Chemische Fabrik Budenheim; Rudolf A. Oetker) (1995). USPatent No. 5,387,655.

77. Aslin, D. (to Prometheus Developments Ltd) (2004). British PatentApplication No. 2 401 367.

78. Gobelbecker, S., Nagerl, H.-D., Danker, G. and Kirk, D. (to Akro-FireguardProducts; Chemische Fabrik Budenheim). European Patent ApplicationNo. 0 614 944.

79. Bradford, S., Hallam, S. and Taylor, A. (to Leigh’s Paints) (2007). BritishPatent Application No. 2,451,233.

80. Andersson, A., Lundmark, S. and Maurer, F. (2007). Evaluation andCharacterization of Ammonium Polyphosphate-Pentaerythritol-Based Systemsfor Intumescent Coatings, Journal of Applied Polymer Science, 104(2): 748–753.

290 E. D. WEIL

81. Harden, A. and Velin, P. (to Perstorp Specialty Chemicals) (2006). PCTPatent Application No. WO 2006096112.

82. Jenewein, E. and Pirig, W.-D. (to Hoechst AG) (1996). European PatentApplication No. 0 735 119.

83. Wang, J., Yang, S., Li, G. and Jiang, J. (2003). Synthesis of a New-TypeCarbonific and Its Application in Intumescent Flame-retardant (IFR)/Polyurethane Coatings, Journal of Fire Sciences, 21(4): 245–266.

84. Wladyka-Przybylak, M. and Kozlowski, R. (1999). The ThermalCharacteristics of Different Intumescent Coatings, Fire and Materials,23(1): 33–43.

85. Duquesne, S. and Bourbigot, S. (2009). Char Formation andCharacterization, In: Wilkie, C. and Morgan, A. (eds), Fire Retardancy ofPolymeric Materials, 2nd edn, pp. 239–260, CRC Press, Boca Raton, FL.

86. Horacek, H. (2009). Reactions of Stoichiometric Intumescent Paints,Journal of Applied Polymer Science, 113(3): 1745–1756.

87. Ellard, J. (1973). Performance of Intumescent Fire Barriers, Division ofOrganic Coatings and Plastics Chemistry, ACS 165th Meeting, Dallas, TX,April 8–13.

88. Langille, K.B., Nguyen, D., Veinot, D.E. and Bernt, J.O. (to PyrophoricSystems Ltd) (2003). US Patent No. 6,645,278.

89. Langille, K.B., Nguyen, D., Bernt, J.O., Veinot, D.E. and Murthy, M.K.(1993). Constitution and Properties of Phosphosilicate Coatings, Journal ofMaterials Science, 28(15): 4175–4187.

90. Veinot, D., Nguyen, D., Langille, K. and Sorathia, U. (1999). InorganicIntumescent Coating for Improved Fire Protection of GRP,44th International SAMPE Symposium, Long Beach, CA, 23–27 May,pp. 1385–1394.

91. Wainwright, R. and Evans, K. (to Alcan International Ltd) (1996). USPatent No. 5,532,292.

92. Erismann, D. and Vesley, G. (to 3M) (2002). US Patent Application No.20020171068.

93. Phillips, G. (to National Research Development Corp.) (1974). BritishPatent No. 1,373,908.

94. Dimanshteyn, F. (to Firestop Chemical Corp.) (1991). US Patent No.5,035,951.

95. Hanafin, J. (to Textron) (2000). US Patent No. 6,096,812.

96. Jimenez, M., Duquesne, S. and Bourbigot, S. (2006). Characterization of thePerformance of an Intumescent Fire Protective Coating, Surface andCoatings Technology, 201: 979–987.

97. Jimenez, M., Duquesne, S. and Bourbigot, S. (2006). Intumescent FireProtective Coatings: Toward a Better Understanding of Their Mechanism ofAction, Thermochimica Acta, 449: 16–26.

98. Nugent, R., Ward, T., Greigger, P. and Seiner, J. (to PPG Industries). USPatent No. 5,108,832.

99. Ward, T., Greigger, P., Matheson, R., Alveberg, B.-E. and Alveberg, J.(1996). Epoxy Intumescent Coatings, PCE, Dec 1996: 16–23.


100. Kobayashi, N., Yoshioki, S., Yoshida, K., Sagawa, K. and Ishihara, S.(to Dainippon Ink and Chemicals, Inc.) (1995). US Patent No. 5,401,793.

101. Gottfried, S. (to No Fire Technologies, Inc.) (1998). US Patent No.5,723,515.

102. Green, J., Allen, W., Taylor, A. and Butterfield, S. (to W. & J. Leigh & Co.)(2006). PCT Patent Application No. WO 2006/067478.

103. Olcese, T. and Pagella, C. (1999). Vitreous Fillers in Intumescent Coatings,Progress in Organic Coatings, 36: 231–241.

104. Koo, J., Ng, P. and Cheung, F. (1997). Effect of High TemperatureAdditives in Fire Resistant Materials, Journal of Fire Sciences, 15(6):488–504.

105. Koo, J.H. and Pilato, L.A. (2006). Fire-Retardant Nanocomposite Coatings,part of chapter 16, Thermal Properties and Microstructures of PolymerNanostructured Materials, In: Schulz, M.J., Kelkar, A. and Sundaresan,M.J. (eds), Nanoengineering of Structural, Functional and SmartMaterials, pp. 414–416, CRC Press, Boca Raton, FL.

106. Hassan, M., Kozlowski, R. and Obidzinski, B. (2008). New Fire-ProtectiveIntumescent Coatings for Wood, Journal of Applied Polymer Science,110(1): 83–90.

107. Camino, G. and Fina, A. (2008). New Perspectives in Fire RetardantCoatings, Pitture e Vernici: European Coatings, 7(64): 1–5.

108. Malucclli, G., Han, Z., Fina, A. and Camino, G. (2010). IntumescentCoatings for the Protection of Steel Structures: State of the Art andPerspectives, paper presented at Fire Retardant Coatings IV, EuropeanCoatings Conference, Berlin, Germany, 3–4 June.

109. Hu, X. and Koo, J.H. (2001). Flammability Studies on a Water-BorneFlame Retardant Nanocomposite Coating on Wood, paper presented atProceedings of Polymer Nanocomposites Symposium, ACS SouthwestRegional Meeting, San Antonio, TX, 17–20 October.

110. Wang, Z., Han, E. and Ke, W. (2006). Effect of Acrylic Polymer andNanocomposite with Nano-SiO2 on Thermal Degradation and FireResistance of APP-DPER-MEL Coating, Polymer Degradation andStability, 91(9): 1937–1947.

111. Rhodes, M., Izraelev, L., Tuerack, J. and Rhodes, P. (to BroadviewTechnology) (2004). PCT Patent Application No. WO 2004/009691.

112. Liu, F. and Zhu, W. (to J.M. Huber Corp.) (1999). US Patent No. 5,968,669.

113. Hallisey, G., Higbie, W., Camarota, A. and Rowan, J. (to Avtec Industries)(2005). US Patent No. 6,960,388.

114. Rowen, J. (to Avtec Industries) (2008). US Patent No. 7,331,400.

115. Ford, B., Hutchings, D., Foucht, M., Qureshi, S., Garvey, C. andKrassowski, D. (to Georgia-Pacific Resins) (2001). US Patent No.6,228,914.

116. Benitez, J. and Giudice, C. (1998). Phosphorus-BasedIntumescent Coatings, Cidepint, 1997–1998: 45–62; Chemical Abstract,130: 169582.

292 E. D. WEIL

117. O’Brien, P. and Schofield, C. (to Fire & Vision Ltd) (2000). PCT PatentApplication No. 00/14167.

118. Duquesne, S., Delobel, R., Magnet, S. and Jama, C. (to Eliokem) (2004).European Patent Application No. 1 431 353.

119. Fream, A. and Magnet, S. (2004). The Development of Novel Latexesfor Fire-Resistant Intumescent Coatings, Paint and Coatings Industry,June 2004: 64–73.

120. Magnet, S., Duquesne, S., Delobel, R. and Jama, C. (to Eliokem S.A.S.)(2003). US Patent No. 7,105,605.

121. Duquesne, S., Magnet, S., Jama, C. and Delobel, R. (2004). IntumescentPaints: Fire Protective Coatings for Metallic Substrates, Surface andCoating Technology, 180–181: 302–307.

122. Duquesne, S., Magnet, S., Jama, C. and Delobel, R. (2005). ThermoplasticResins for Thin Film Intumescent Coatings – Towards a BetterUnderstanding of their Effect on Intumescence Efficiency, PolymerDegradation and Stability, 88(1): 63–69.

123. Green, J. and Allen, W. (to W. & J. Leigh) (2005). PCT Patent ApplicationNo. WO 2005/000975.

124. Green, J., Allen, W. and Taylor, A. (to W. & J. Leigh & Co.) (2006). PCTPatent Application No. WO 2006/067488.

125. Farrell, P. and Green, J. (to W. & J. Leigh & Co.) (2002). PCT PatentApplication No. WO 02/096996.

126. Schmitt, G., Neugebauer, P., Scholl, S., Heeb, H., Reinhard, P. andKuhl, G. (to Evonik Rohm GmbH). PCT Patent Application No. WO 2009/013089 (2009).

127. Ward, T., Greer, S., Boberski, W. and Seiner, J. (1985). US Patent No. 4529 467.

128. Ward, T., Greigger, P. and Seiner, J. (1991). US Patent No. 5 070 119.

129. Nugent, R., Ward, T., Greigger, P. and Seiner, J. (1992). US Patent No. 5108 832.

130. Sinclair, M. and Watts, J. (2008). US Patent No. 7 217 753.

131. Hanafin, J. and Bertrand, D. (2000). US Patent No. 6 096 812.

132. Thewes, V. and Hennemann, A. (2008). European Patent No. 1 627 896.

133. Gottfried, S. (to No Fire Technologies Inc.) (2000). US Patent No.6,074,714.

134. Gottfried, S. (to No Fire Technologies Inc.) (1999). US Patent No.5,985,385.

135. McGinniss, V., Dick, R., Russell, R. and Rogers, S. (to Battelle MemorialInstitute) (1999). US Patent No. 5,925,457.

136. De Keyser, F. (to Monsanto Europe SA) (1995). US Patent No. 5,413,828.

137. Reyes, J. (to JJI Technologies LLC) (2008). US Patent Application No.2008/0277136.

138. Nuzzo, C. (to United States Mineral Products Co.; Isolatek International)(2007). PCT Patent Application No. WO 2007 102,080.


139. Anon. (2009). New Intumescent Protects SPF from Fire, Durability þDesign (the Journal of Architectural Coatings). Available at: http://durabilityanddesign.com/news/?fuseaction¼view&id¼3347 (accessed dateNovember 17, 2009).

140. Hansel, J.-G. and Mauerer, O. (to Lanxess Deutschland GmbH) (2009). USPatent Application No. 2009/0220762.

141. Mabey, M. and Kish, W. (to No-Burn Investments LLC) (2009). US PatentNo. 7,482,395.

142. Mabey, M. and Kish, W. (to No-Burn Investments LLC) (2008). US PatentApplication No. 2008/00542390.

143. Caze, C., Devaux, E., Testard, G. and Reix, T. (1998). New IntumescentSystems: An Answer to the Flame Retardant Challenges in the TextileIndustry, In: Le Bras, M., Camino, G., Bourbigot, S. and Delobel, R. (eds),Fire Retardancy of Polymers: The Use of Intumescence, pp. 363–375,Royal Society of Chemistry, Cambridge, UK.

144. Marcu, I., Shah, P., Cornman, S., Horvath, S., Church, J. and Reeves, D.(to Noveon) (2008). US Patent Application No. 2008/0124560.

145. Fukuzumi, T., Shirazawa, K. and Uchida, K. (to Nissin Chemical IndustryCo.) (2009). US Patent Application No. 2009/0215932.

146. Horrocks, A.R., Wang, M.Y., Hall, M.E., Sunmonu, F. and Pearson, J.S.(2000). Flame Retardant Textile Back-Coatings. Part 2. Effectiveness ofPhosphorus-Containing Flame Retardants in Textile Back-CoatingFormulations, Polymer International, 49: 1079–1091.

147. Bonduel, T. (2010). Carbon Nanotubes/Silicone Nanocomposites for FlameResistant Coatings, paper presented at Fire Retardant Coatings IV,European Coatings Conference, Berlin, Germany, 3–4 June.

148. Pandee, J.L and Banerjee, M.K. (1997). High-Temperature-Resistant(Slurry-Based) Coatings, Anti-Corrosion Methods and Materials, 44(6):368–375.

149. Burton, D. and Holm, J. (to High Performance Coatings Inc.) (2008). PCTPatent Application No. WO 2008060699.

150. Alexander, G., Cheng, Y.-B., Burford, R., Shanks, R., Mansouri, J., Hodzic,A., Wood, C., Genovese, A., Barber, K. and Rodrigo, P. (to PolymersAustralia PTY Ltd) (2004). PCT Patent Application No. WO 2004/013255.

151. Alexander, G., Cheng, Y.-B., Burford, R., Shanks, R., Mansouri, J., Barber,K., Rodrigo, P. and Preston, C. (to Ceram Polymerik Pty Ltd) (2007). USPatent Application No. 2007/0246240.

152. Thompson, K., Rodrigo, P., Preston, C. and Griffin, G. (2006). In the FiringLine, European Coatings Journal, 12: 34–39.

153. Al-Hassany, Z., Genovese, A. and Shanks, R. (2010). Fire-Retardant andFire-Barrier Poly(vinyl acetate) Composites for Sealant Applications,Express Polymer Letters, 4(2): 79–93.

154. Sorathia, U., Gracik, T., Ness, J., Hunstad, M. and Berry, F. (2003).Evaluation of Intumescent Coatings for Shipboard Fire Protection,Journal of Fire Sciences, 21(6): 423–450.

155. Hanafin, J. and Hu, Y. (2002). Intumescent Coatings for the Protectionof Steel, paper presented in Recent Advances in Flame Retardancy

294 E. D. WEIL

of Polymeric Materials, 13th Annual BCC Conference, Stamford, CT,3–5 June.

156. Koo, J.H., Wootan, W., Chow, W.K., Au Yeung, H.W. and Venumbaka, S.(2001). Flammability Studies of Fire Retardant Coatings on Wood,Chapter 28, In: Nelson, G.L. and Wilkie, C.A. (eds), Fire andPolymers Materials and Solutions for Hazard Prevention, ACSSymposium Series 797, American Chemical Society, Washington, DC, pp.361–374.

157. Gottfried, S. (2002). Fire Protection Coatings and the SOLAS codes, paperpresented in Recent Advances in Flame Retardancy of Polymeric Materials,13th Annual BCC Conference, Stamford, CT, 3–5 June.

158. Jimenez, M., Duquesne, S. and Bourbigot, S. (2006). High-Throughput FireTesting for Intumescent Coatings, Industrial and Engineering ChemistryResearch, 45(22): 7475–7481.

159. Bishop, D., Bottomley, D. and Zobel, F. (1983). Fire Retardant Paints,Journal of the Oil and Colour Chemists Association, 66(12): 373–395.

160. Landin, H. (to Minnesota Mining and Manufacturing) (1998). US PatentNo. 5,830,319.

161. Buckingham, M. and Welna, W. (to 3M) (2004). US Patent No. 6,747,074.

162. Welna, W. (to Minnesota Mining and Manufacturing) (1996). US PatentNo. 5,578,671.

163. Reinheimer, A., Wenzel, A. and Muenzenberger, H. (to Hilti AG) (2009).US Patent No. 7,479,513.

164. Muenzenberger, H., Heimpel, F., Rump, S., Forg, C. and Lieberth, W.(to Hilti AG) (2004). US Patent No. 6,706,774.

165. Ackerman, E. (to Rectorseal Corp.) (2001). US Patent No. 6,207,085.

166. Stahl, J. (to Specified Technologies Inc.) (1992). US Patent No. 5,137,658.

167. Schauber, T., Hellback, B., Baser, E. and Malrose, N. (to Doyma GmbH)(2009). European Patent Application No. 2 088 183.

168. Zweynert, M. (2009). Flame Retardant Gelcoats, paper at presented atThermosets 2009 From Monomer to Components, Berlin, Germany,September 30, 2009.

169. Norwood, L. (1999). Fire resistance to satisfy market needs, paper inComposites in Fire, Proceedings of the International Conference, 1st,Newcastle upon Tyne, UK, 15–16 September (published in 2001 byWoodhead Publishing Ltd, Cambridge, UK). pp. 24–37.

170. Reilly, T. and Dietz, M. (2009). Flame Retarded ThermosetMaterials Based on Phosphorus Chemistry, paper presented atThermoset Resin Formulators Association meeting, Pittsburgh, PA,14–15 September.

171. Pagella, C., Epifani, R. and Baldi, G. (2008). New Driving Forcesfor Intumescent Coatings, Pitture e Vernici, European Coatings, 84(4):17–29.

172. Mabey, M. and Kish, W. (2010). US Patent Application No.20100069488.

173. Kawamura, Y. (to Kikusui Chemical Industries, Ltd) (2010). JapeneseKokai Tokkyu Koho 138,217; Chemical Abstracts, 153: 64492.


BIOGRAPHY

Edward D. Weil

Dr. Weil received his BS degree in chemistry from University ofPennsylvania in 1950 and his PhD degree in organic (polymer)chemistry from University of Illinois in 1953. He conducted andmanaged research in industry (Hooker Chemical Co., StaufferChemical Co.) for 33 years and has served as Research Professor atPolytechnic University (now Polytechnic Institute of NYU) since 1987.His industrial and academic research has covered a wide variety of flameretardancy topics, has led to many patents and several commercial flameretardants and he consults actively in this field. He has authored manypapers and encyclopedia articles in flame retardants, phosphorus,chlorine and sulfur chemistry. The present review supplements hisco-authored book (2009) on flame retardants for plastics and textiles.

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Documents

Fire-Protective and Flame-Retardant Coatings – A State · PDF fileFire-Protective and Flame-Retardant Coatings ... A formulation of 18.6% rutile (TiO 2), 12.7% barium metaborate,