CA2334274A1 - Expandable graphite as a flame retardant in unsaturated polyester resins - Google Patents
Expandable graphite as a flame retardant in unsaturated polyester resins Download PDFInfo
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Abstract
The present invention relates to flame retardant compositions, useful for providing protection from fire to a substrate, such as fibreboard or strandboard. More particularly, the present invention relates to unsaturated polyester resin intumescent compositions containing particles of expandable graphite.
Description
Description EXPANDABLE GRAPHITE AS A FLAME RETARDANT
IN UNSATURATED POLYESTER RESINS
Technical Field The present invention relates to flame retardant compositions, useful for providing protection from fire to a substrate, such as fibreboard or strandboard. More specifically, the present invention relates to unsaturated polyester resin intumescent compositions containing particles of expandable graphite. The flammability of the crosslinked polyester resin is reduced by the addition of particles of expandable graphite, even at levels as low as 7 pph.
The expandable graphite is particularly effective when used in conjunction with ammonium polyphosphate or a halogen compound as a synergist.
Background Art Chemical intumescent systems have been used as flame retardants for over 50 years.
Typically based on phosphates, melamine, and pentaerythritol, these intumescents rely on heat-induced decomposition to generate a char layer that insulates the substrate from the heat source. As such, they are most useful as coatings for flammable materials.
When added into many materials, however, the expansive force of chemical intumescents is often insufficient to generate an effective char layer. For example, it has been found that many thermoset phenolic or unsaturated polyester resins cannot be protected by the incorporation of chemical intumescents.
Expandable graphite flake is now being used in a growing number of applications as an intumescent fire retardant additive, as an expansive agent, and as a smoke suppressant.
Ford et al. describe the use of expandable graphite in oriented strandboard panels to reduce the flame spread in U.S. Patent 5,443,894. Hutchings et al. developed an especially effective intumescent coating containing expandable graphite that reduced the flame spread and smoke of highly combustible fibreboard panels, as described in a paper titled "Expandable Graphite Flake As An Additive For A New Flame Retardant Resin," presented at the Fire Retardant Chemicals Association Fall Meeting, Naples, Florida, pp. 137-146 (October 1996). Many intumescent putties, caulks and firestop systems rely on expandable graphite to provide the expansive force necessary to close off gaps and holes during the course of a fire. Expandable graphite is also used in various polyurethane foams to pass the rigorous tests required of aircraft seating and construction insulation, as described in U.K. Patent Application 2,168,706.
The fire retardant properties of a number of thermoplastic polymers with expandable graphite and synergists was described by Okisaki in "Flamecut GREP Series New Non-Halogenated Flame Retardant Systems," presented at the Fire Retardant Chemicals Association Spring Meeting, San Francisco, California, pp. 11-24 (March 1997).
For many applications, there is a need for unsaturated polyester resins (UPRs) to be fire retardant or self extinguishing. Fibre-reinforced plastic (FRP) materials containing UPRs are of particular concern, since this material is often used in critical applications such as aircraft, shipbuilding, and building construction.
The fire retardancy of UPRs has been recognized in the past. Chlorine and bromine compounds (e.g. HET acid, tetrachlorophthalic anhydride, tetrabromophthalic anhydride, dibromoneopentyl glycol) can be built into the UPR molecule, or added to the UPR directly as pentabromoethylbenzene or various chloroparaffins. The mechanism of fire retardancy involves the formation of Cl or Br radicals that terminate the radical chain reaction of flame propagation. Antimony trioxide is often used to enhance the fire retardant efficiency of halogen compounds. However, the use of halogenated compounds and antimony oxide has come under some criticism due to the possible formation of toxic or corrosive combustion products.
Aluminum trihydroxide Al(OH)3 and magnesium hydroxide Mg(OH)2 exhibit a different mechanism of fire retardancy. Both materials evolve water at high temperatures, thus decreasing the temperature of the substrate and diluting the combustible pyrolysis gases.
The primary disadvantage of these fire retardants is that they require relatively high loadings to be effective. This makes impregnation of the fiber reinforced composite more difficult while reducing its final physical properties. The metal hydroxides do have an important advantage in that they can significantly decrease the evolution of smoke.
A still different mechanism of fire retardancy is observed when red phosphorus and phosphorus compounds (e.g. triethyl phosphate or ammonium polyphosphate) are used. The oxidation and pyrolysis of these compounds result in the formation of polyphosphoric acid.
The acids tend to promote charring of the plastic during heating, which acts to reduce burning. Moreover, the char formation decreases the concentration of gaseous hydrocarbons due to pyrolysis. The concentration of phosphorus is usually much less than that required for the Al or Mg hydroxides. In fact, if the amount of the phosphorous-containing fire retardants is too large some properties of the UPRs may be adversely affected and processing problems may arise.
There have been many acidic metal compounds suggested for use as flame retardants.
The fire retardant mechanism of these compounds may be similar to that of phosphorus-containing compounds. In addition to the well-known zinc borates, tin compounds (zinc stannate, ZnSn03 and zinc hydroxystannate, ZnSn(OH)6) have also been suggested as possible fire retardants and smoke suppressants.
As mentioned above, a flame retardant system must reduce the generation of smoke as well as suppress the flame propagation. In addition to A1 and Mg hydroxides and the borates and stannates, molybdenum trioxide (Mo03) is an efficient smoke suppressant. The effect of the various smoke suppressants depends on the temperature of pyrolysis.
Combinations of various fire retardants can exhibit an elevated efficiency when the mechanism of fire retardancy is different. For example, halogen compounds form synergistic systems with Al(OH)3 or phosphorus compounds. Halogen-free systems containing Al(OH)3 with red phosphorus or ammonium polyphosphate can be somewhat effective.
Phosphorus-phosphorus synergism was found when triethyl phosphate was added together with melamine polyphosphate.
IN UNSATURATED POLYESTER RESINS
Technical Field The present invention relates to flame retardant compositions, useful for providing protection from fire to a substrate, such as fibreboard or strandboard. More specifically, the present invention relates to unsaturated polyester resin intumescent compositions containing particles of expandable graphite. The flammability of the crosslinked polyester resin is reduced by the addition of particles of expandable graphite, even at levels as low as 7 pph.
The expandable graphite is particularly effective when used in conjunction with ammonium polyphosphate or a halogen compound as a synergist.
Background Art Chemical intumescent systems have been used as flame retardants for over 50 years.
Typically based on phosphates, melamine, and pentaerythritol, these intumescents rely on heat-induced decomposition to generate a char layer that insulates the substrate from the heat source. As such, they are most useful as coatings for flammable materials.
When added into many materials, however, the expansive force of chemical intumescents is often insufficient to generate an effective char layer. For example, it has been found that many thermoset phenolic or unsaturated polyester resins cannot be protected by the incorporation of chemical intumescents.
Expandable graphite flake is now being used in a growing number of applications as an intumescent fire retardant additive, as an expansive agent, and as a smoke suppressant.
Ford et al. describe the use of expandable graphite in oriented strandboard panels to reduce the flame spread in U.S. Patent 5,443,894. Hutchings et al. developed an especially effective intumescent coating containing expandable graphite that reduced the flame spread and smoke of highly combustible fibreboard panels, as described in a paper titled "Expandable Graphite Flake As An Additive For A New Flame Retardant Resin," presented at the Fire Retardant Chemicals Association Fall Meeting, Naples, Florida, pp. 137-146 (October 1996). Many intumescent putties, caulks and firestop systems rely on expandable graphite to provide the expansive force necessary to close off gaps and holes during the course of a fire. Expandable graphite is also used in various polyurethane foams to pass the rigorous tests required of aircraft seating and construction insulation, as described in U.K. Patent Application 2,168,706.
The fire retardant properties of a number of thermoplastic polymers with expandable graphite and synergists was described by Okisaki in "Flamecut GREP Series New Non-Halogenated Flame Retardant Systems," presented at the Fire Retardant Chemicals Association Spring Meeting, San Francisco, California, pp. 11-24 (March 1997).
For many applications, there is a need for unsaturated polyester resins (UPRs) to be fire retardant or self extinguishing. Fibre-reinforced plastic (FRP) materials containing UPRs are of particular concern, since this material is often used in critical applications such as aircraft, shipbuilding, and building construction.
The fire retardancy of UPRs has been recognized in the past. Chlorine and bromine compounds (e.g. HET acid, tetrachlorophthalic anhydride, tetrabromophthalic anhydride, dibromoneopentyl glycol) can be built into the UPR molecule, or added to the UPR directly as pentabromoethylbenzene or various chloroparaffins. The mechanism of fire retardancy involves the formation of Cl or Br radicals that terminate the radical chain reaction of flame propagation. Antimony trioxide is often used to enhance the fire retardant efficiency of halogen compounds. However, the use of halogenated compounds and antimony oxide has come under some criticism due to the possible formation of toxic or corrosive combustion products.
Aluminum trihydroxide Al(OH)3 and magnesium hydroxide Mg(OH)2 exhibit a different mechanism of fire retardancy. Both materials evolve water at high temperatures, thus decreasing the temperature of the substrate and diluting the combustible pyrolysis gases.
The primary disadvantage of these fire retardants is that they require relatively high loadings to be effective. This makes impregnation of the fiber reinforced composite more difficult while reducing its final physical properties. The metal hydroxides do have an important advantage in that they can significantly decrease the evolution of smoke.
A still different mechanism of fire retardancy is observed when red phosphorus and phosphorus compounds (e.g. triethyl phosphate or ammonium polyphosphate) are used. The oxidation and pyrolysis of these compounds result in the formation of polyphosphoric acid.
The acids tend to promote charring of the plastic during heating, which acts to reduce burning. Moreover, the char formation decreases the concentration of gaseous hydrocarbons due to pyrolysis. The concentration of phosphorus is usually much less than that required for the Al or Mg hydroxides. In fact, if the amount of the phosphorous-containing fire retardants is too large some properties of the UPRs may be adversely affected and processing problems may arise.
There have been many acidic metal compounds suggested for use as flame retardants.
The fire retardant mechanism of these compounds may be similar to that of phosphorus-containing compounds. In addition to the well-known zinc borates, tin compounds (zinc stannate, ZnSn03 and zinc hydroxystannate, ZnSn(OH)6) have also been suggested as possible fire retardants and smoke suppressants.
As mentioned above, a flame retardant system must reduce the generation of smoke as well as suppress the flame propagation. In addition to A1 and Mg hydroxides and the borates and stannates, molybdenum trioxide (Mo03) is an efficient smoke suppressant. The effect of the various smoke suppressants depends on the temperature of pyrolysis.
Combinations of various fire retardants can exhibit an elevated efficiency when the mechanism of fire retardancy is different. For example, halogen compounds form synergistic systems with Al(OH)3 or phosphorus compounds. Halogen-free systems containing Al(OH)3 with red phosphorus or ammonium polyphosphate can be somewhat effective.
Phosphorus-phosphorus synergism was found when triethyl phosphate was added together with melamine polyphosphate.
What is desired, therefore, is an additive effective to increase the fire retardancy of compositions based on crosslinked polymers (e.g. unsaturated polyester resins). The additive should be capable of improving fire retardancy and related properties at relatively low levels, and act synergistically with other fire retardant compositions to improve the fire retardancy achieved.
Summary of the Invention It is an object of the present invention to provide an unsaturated polyester resin having improved fire retardancy.
It is another object of the invention to provide an unsaturated resin having particles of expandable graphite as an intumescent additive.
It is yet another object of the present invention to provide a fire retardant composition comprising an unsaturated polyester resin having particles of expandable graphite and a synergistic fire retardancy-enhancing compound mixed therein.
These objects and others which will become apparent to the artisan upon review of the following description can be accomplished by providing a fire retardant composition which comprises an unsaturated polyester resin which includes as an additive particles of expandable graphite. The particles of expandable graphite are present in the polyester resin at levels of at least about 7.5 parts by weight of expandable graphite particles per 100 parts resin (phr) when the particles of expandable graphite are the only additive, and at least 5 phr when the expandable graphite particles are used in combination with a synergistic additional fire retardant compound.
Graphites are made up of layer planes of hexagonal arrays or networks of carbon atoms. These layer planes of hexagonally arranged carbon atoms are substantially flat and are oriented or ordered so as to be substantially parallel and equidistant to one another. The substantially flat, parallel equidistant sheets or layers of carbon atoms, usually referred to as basal planes, are linked or bonded together and groups thereof are arranged in crystallites.
Highly ordered graphites consist of crystallites of considerable size, the crystallites being highly aligned or oriented with respect to each other and having well ordered carbon layers.
In other words, highly ordered graphites have a high degree of preferred crystallite orientation. Briefly, graphites may be characterized as laminated structures of carbon, that is, structures consisting of superposed layers or laminae of carbon atoms joined together by weak van der Waals forces. In considering the graphite structure, two axes or directions are usually noted, to wit, the "c" axis or direction and the "a" axes or directions. For simplicity, the "c" axis or direction may be considered as the direction perpendicular to the carbon layers. The "a" axes or directions may be considered as the directions parallel to the carbon layers (parallel to the planar direction of the crystal structure of the graphite) or the directions perpendicular to the "c" direction.
As noted above, the bonding forces holding the parallel layers of carbon atoms together are only weak van der Waals forces. Graphites can be treated so that upon the application of heat, the spacing between the superposed carbon layers or laminae can be appreciably opened up so as to provide a marked expansion in the direction perpendicular to the layers, that is, in the "c" direction and thus form an expanded graphite structure (also referred to as exfoliated or intumesced graphite) in which the laminar character of the carbon layers is substantially retained. Upon exposure to a flame, the graphite particles expand (or exfoliate) to form a mechanical and insulative barrier to fire.
Brief Description of the Drawings The present invention will be better understood and its advantages more apparent in view of the following detailed description, especially when read with reference to the appended Figure, which is a photomicrograph of a particle of expanded graphite.
Detailed Description of the Invention Expandable graphite is manufactured using natural crystalline graphite flake.
Deposits of crystalline graphite are numerous and found around the world, usually as inclusions in metamorphic rock, or in the silts and clays that result from their erosion.
Summary of the Invention It is an object of the present invention to provide an unsaturated polyester resin having improved fire retardancy.
It is another object of the invention to provide an unsaturated resin having particles of expandable graphite as an intumescent additive.
It is yet another object of the present invention to provide a fire retardant composition comprising an unsaturated polyester resin having particles of expandable graphite and a synergistic fire retardancy-enhancing compound mixed therein.
These objects and others which will become apparent to the artisan upon review of the following description can be accomplished by providing a fire retardant composition which comprises an unsaturated polyester resin which includes as an additive particles of expandable graphite. The particles of expandable graphite are present in the polyester resin at levels of at least about 7.5 parts by weight of expandable graphite particles per 100 parts resin (phr) when the particles of expandable graphite are the only additive, and at least 5 phr when the expandable graphite particles are used in combination with a synergistic additional fire retardant compound.
Graphites are made up of layer planes of hexagonal arrays or networks of carbon atoms. These layer planes of hexagonally arranged carbon atoms are substantially flat and are oriented or ordered so as to be substantially parallel and equidistant to one another. The substantially flat, parallel equidistant sheets or layers of carbon atoms, usually referred to as basal planes, are linked or bonded together and groups thereof are arranged in crystallites.
Highly ordered graphites consist of crystallites of considerable size, the crystallites being highly aligned or oriented with respect to each other and having well ordered carbon layers.
In other words, highly ordered graphites have a high degree of preferred crystallite orientation. Briefly, graphites may be characterized as laminated structures of carbon, that is, structures consisting of superposed layers or laminae of carbon atoms joined together by weak van der Waals forces. In considering the graphite structure, two axes or directions are usually noted, to wit, the "c" axis or direction and the "a" axes or directions. For simplicity, the "c" axis or direction may be considered as the direction perpendicular to the carbon layers. The "a" axes or directions may be considered as the directions parallel to the carbon layers (parallel to the planar direction of the crystal structure of the graphite) or the directions perpendicular to the "c" direction.
As noted above, the bonding forces holding the parallel layers of carbon atoms together are only weak van der Waals forces. Graphites can be treated so that upon the application of heat, the spacing between the superposed carbon layers or laminae can be appreciably opened up so as to provide a marked expansion in the direction perpendicular to the layers, that is, in the "c" direction and thus form an expanded graphite structure (also referred to as exfoliated or intumesced graphite) in which the laminar character of the carbon layers is substantially retained. Upon exposure to a flame, the graphite particles expand (or exfoliate) to form a mechanical and insulative barrier to fire.
Brief Description of the Drawings The present invention will be better understood and its advantages more apparent in view of the following detailed description, especially when read with reference to the appended Figure, which is a photomicrograph of a particle of expanded graphite.
Detailed Description of the Invention Expandable graphite is manufactured using natural crystalline graphite flake.
Deposits of crystalline graphite are numerous and found around the world, usually as inclusions in metamorphic rock, or in the silts and clays that result from their erosion.
Graphite is recovered from the ore by crushing and flotation, and is usually beneficiated to give graphite flake that is 95-98% carbon.
As discussed above, graphite is a crystalline form of carbon comprising atoms covalently bonded in flat layered planes with weaker bonds between the planes.
By treating particles of graphite, such as natural graphite flake, with an intercalant of, e.g. a solution of sulfuric and nitric acid, the crystal structure of the graphite reacts to form a compound of graphite and the intercalant. The treated particles of ~aphite are referred to as "particles of intercalated graphite." Upon exposure to high temperature, the particles of intercalated graphite expand in dimension as much as 80 or more times their original volume in an accordion-like fashion in the "c" direction, i. e. in the direction perpendicular to the crystalline planes of the graphite, thus the particles of intercalated graphite can also be referred to as particles of expandable graphite." Exfoliated graphite particles are vermiform in appearance, and are therefore commonly referred to as worms. The worms act as a barrier to fire, both mechanically and because of their insulative value.
A common method for manufacturing particles of expandable graphite is described by Shane et al. in U.S. Pat. No. 3,404,061, the disclosure of which is incorporated herein by reference. In the typical practice of the Shane et al. method, natural graphite flakes are intercalated by dispersing the flakes in a solution containing e.g., a mixture of nitric and sulfuric acid. The intercalation solution contains oxidizing and other intercalating agents known in the art. Examples include those containing oxidizing agents and oxidizing mixtures, such as solutions containing nitric acid, potassium chlorate, chromic acid, potassium permanganate, potassium chromate, potassium dichromate, perchloric acid, and the like, or mixtures, such as for example, concentrated nitric acid and chlorate, chromic acid and phosphoric acid, sulfuric acid and nitric acid, or mixtures of a strong organic acid, e.g.
trifluoroacetic acid, and a strong oxidizing agent soluble in the organic acid.
In a preferred embodiment, the intercalating agent is a solution of a mixture of sulfuric acid, or sulfuric acid and phosphoric acid, and an oxidizing agent such as nitric acid, perchloric acid, chromic acid, potassium permanganate, hydrogen peroxide, iodic or periodic acids, or the like. Although less preferred, the intercalation solution may contain metal halides such as ferric chloride, and ferric chloride mixed with sulfuric acid, or a halide, such as bromine as a solution of bromine and sulfuric acid or bromine in an organic solvent.
After the flakes are intercalated, any excess solution is drained from the flakes and the flakes are water-washed. The quantity of intercalation solution retained on the flakes after draining may range from 20 to 150 parts of solution by weight per 100 parts by weight of graphite flakes (pph) and more typically about 50 to 120 pph. Alternatively, the quantity of the intercalation solution may be limited to between 10 to 50 parts of solution per hundred parts of graphite by weight (pph) which permits the washing step to be eliminated as taught and described in U.S. Pat. No. 4,895,713, the disclosure of which is also herein incorporated by reference.
When the intercalated graphite is exposed to heat or flame, such as in a fire, the inserted molecules decompose to generate gas. The gas forces apart the carbon layers and the graphite expands. The expanded graphite is a low density, non-burnable, thermal insulation, often referred to as a "worm" because of its curved shape (Figure). For use in the inventive composition, the particles of expandable graphite should preferably expand at temperatures no higher than about 300°C, preferably no higher than about 250°C. Suitable expandable graphites are commercially available from UCAR Graph-Tech, Inc. of Lakewood, Ohio and include UCAR Graph-Tech's GRAFGUARD~ Grade 220 expandable graphite flake and GRAFGUARD~ Grade 160 expandable graphite flake. The principal functional difference between the two grades is onset temperature, that is, the temperature at which expansion begins. For the GRAFGUARD~ Grade 220 expandable graphite flake, expansion begins at 220°C, whereas for GRAFGUARD~ Grade I60 expandable graphite flake, expansion begins at 160°C.
The unsaturated polyester resin (UPR) into which the particles of expandable graphite can be incorporated to form the inventive intumescent composition comprise solutions of unsaturated polyesters (UPs) and similar products in unsaturated monomers that can be cured by radical copolymerization. UPs are composed of glycol and dicarboxylic acid units which include unsaturated copolymerizable acid units and saturated or unsaturated non-copolymerizable acid units. The unsaturated copolymerizable acid units are primarily _7_ derived from malefic acid and fumaric acid residues. The saturated or unsaturated acid units are primarily derived from orthophthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, endomethylenetetrahydrophthalic acid, hexachloro-endomethylenetetrahydrophthalic acid, adipic acid, sebacic acid and tetrabromophthalic acid.
A variety of glycol units can also form a part of the structure of UPs, namely ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, dipropylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, neopentyl glycol, dibromoneopentyl glycol, 2-methyl-1,3-propanediol, chloromethylethylene glycol, 2,2,4-trimethyl-1,3-pentanediol, ethoxylated bisphenol A, propoxylated bisphenol A, and 1,4-cyclohexanedimethanol.
The UP molecules contain terminal hydroxyl and carboxylic groups. They can also be terminated with dicyclopentadiene, i.e. with dihydrodicyclopentadienyl ester groups.
The UPs that are chain terminated with brominated monofunctional units, e.g.
2,3-dibromopropyl residues, are included also. Additionally, oligo (ethylene terephthalate) segments can be incorporated.
UPRs commonly contain mostly styrene as the monomer, although the styrene can be partially or entirely replaced by vinyl monomers, e.g. vinyltoluene or p-t-butylstyrene, acrylic monomers, e.g. methyl methacrylate, ethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate or triethylene glycol dimethacrylate, and allyl esters, e.g.
diallyl phthalate, isophthalate or terephthalate. Allyl ethers, e.g. trimethylolpropane monoallyl ether or trimethylolpropane diallyl ether, can also be used as one of the monomers or built into the molecule of an UP.
So-called vinyl ester resins are also UPRs and are cured and processed in the same way. Vinyl ester resins are solutions of unsaturated esters in the above listed unsaturated monomers, mostly styrene. The unsaturated esters are addition products of methacrylic acid to epoxy groups in epoxy resins, mostly bisphenol A diglycidyl ether type, tetrabromobisphenol A diglycidyl ether and epoxynovolak resin. UPRs, comprising vinyl ester resins, are also used in urethanized form. The urethanization consists of the reaction of _g_ a diisocyanate with a part of hydroxyl groups contained in an UP with the maleate/fumarate unsaturation or in the vinyl esters with the methacrylate unsaturation.
The above described UPRs are cured at ambient temperature using an initiator-accelerator system, such as a hydroperoxide or a ketone peroxide with a cobalt salt or a vanadium compound, or benzoyl peroxide with a tetiary aromatic amine (e.g. N,N-dimethylaniline or N,N-dimethyl-p-toluidine); or at elevated temperatures using peroxy compounds with an elevated decomposition temperature, e.g. benzoyl peroxide or dicumyl peroxide.
Fillers containing UPRs can also be used in the compositions according to this invention, together with expandable graphite and optionally other fire retardants. Powdered fillers, e.g. chalk and talc, and fibrous reinforcing fillers, e.g. glass fiber, juts and sizal can also be included.
In forming the inventive flame retardant compositions, particles of expandable graphite are incorporated into the UPR prior to curing. The graphite particles are included in an amount sufficient to exhibit flame retardancy as compared with the UPR
without graphite.
When incorporated without a synergistic agent, the particles of expandable graphite should be incorporated into the resin at a level of at least about 7 parts by weight graphite per 100 parts by weight of UPR (pph), more preferably at least about 7.5 pph. Most preferably, the particles of expandable graphite are included in the resin composition at a level of at least about 10 pph. Although there is no strict upper limit of the amount of graphite particles to be included, generally, no more than about 25 pph should be included, in order to maintain the mechanical strength of the cured resin composition.
In addition to the particles of expandable graphite and UPRs, the inventive flame retardant compositions can also include other components that act synergistically with the graphite particles to create further flame retardancy for the inventive composition. Such synergistic compositions include ammonium phosphate type compositions like ammonium polyphosphate, which tends to form polyphosphoric acid on oxidation and pyrolysis, and promote charring which reduces burning, and halogen compounds such as chlorine compounds and bromine compounds like pentabromoethylbenzene, optionally with an antimony compound like antimony trioxide or antimony pentoxide. These synergistic compounds can be included at levels of at least about 2 pph, and generally not more than about 15 pph. When the synergistic compounds are included the minimum level of graphite particles can be reduced to about 4 pph in the inventive composition.
In use, the compositions of the present invention can be incorporated in or coated on the surface of the substrate to be protected, and then cured. For instance, the inventive compositions can be coated on strandboard or fibreboard, and provide enhanced fire retardancy to the surfaces; or, the particles of expandable graphite can be incorporated in glass fiber reinforced polyester resin (GRP) products, such as GRP products made by the hand-lay-up method, by spraying etc.
In another embodiment of the invention, particles of expandable graphite can also be added to unsaturated polyester-based resin binders with fibrous and powdered fillers. The best example of these are sheet molding compounds (SMCs) which consist of UPR, chalk, cut glass fibers, a thickener, peroxide initiators, pigments and, optionally, a low-profile additive. Expandable graphite (optionally with other fire retardant additives) may be used to make the compression molded parts fire resistant. In such applications, the expandable graphite can be included at lower levels, as low as 5 parts by weight per 100 parts by weight of UPR or even as low as 3 parts by weight if used in conjunction with a synergistic agent like an ammonium phosphate type compound. An exemplary formulation, in parts by weight: general purpose UPR 100, chalk 120, tert-butyl perbenzoate 1.5, Mg0 (thickener) 4.5, zinc stearate 4.5, cut glass fiber 9.5, expandable graphite particles S or, when ammonium polyphosphate is present at 5 parts by weight, then expandable graphite particles can be present at 3 parts by weight.
The following examples are presented to further illustrate and explain the present invention and should not be viewed as limiting in any regard. Unless otherwise indicated, all parts and percentages are by weight, and are based on the weight of the product at the particular stage in processing indicated.
Example I
The resin employed was Polimal 109 unsaturated polyester resin obtained from Chem. Works "Organika-Sarzyna", Nowa Sarzyna, Poland. The resin is a general-purpose, halogen-free system made of malefic anhydride, phthalic anhydride, 1,2-propylene glycol and styrene. The cold curing system consisted of methylethylketone peroxide and cobalt octoate.
The expandable graphite employed was GRAFGUARD~ 220-80N Expandable Graphite Flake, obtained from UCAR Graph-Tech, Inc. of Lakewood, Ohio. As noted above, in the grade nomenclature, 220 refers to the temperature (in °C) at which the graphite begins to expand; in addition 80 refers to the mesh size of the particles ( 177 micron or larger), and N refers to a neutral flake.
The liquid UPR was mixed with the expandable graphite particles (denoted G), at differing levels, and 1 pph Aerosil 200 (to avoid sedimentation). The components of the curing system consisting of 1.5 pph methylethylketone peroxide (40%) and 0.4 pph cobalt octoate solution (1% Co) were added, and the compositions were cast into 4 mm x 10 mm x 100 mm steel molds. The curing was carried out by holding the cast pieces at 20°C for 24 hours, followed by a postcuring treatment at 80°C for 2 hours.
The fire performance of the bars was tested by heating the samples in a horizontal position using a gas flame for 60 seconds, then monitoring the self extinguishing (afterflame) time (and time to extinguish after application of flame) and the remaining non-burnt length of the bar (up to 80 mm). This test corresponds to the Polish Standard PN-82/C-89023 [see ISO
1210:1992 (E) "Plastics-determination of the burning behaviour of horizontal and vertical specimens in contact with a small-flame ignition source"]. In addition, the Limiting Oxygen Index (LOI) was also determined.
The results are shown in Table I.
Table I
Behavior in fire Sample G, pph No. AfterflameNon-burnt Self extinguishing time, length, LOI, sec mm 1 - I 0 No 280 0 19.5 2 - I 5 No 365 0 21.6 3 - I 7.5 Yes 7 78 4 - I 10 Yes 0 80 23.3 - I 15 Yes 0 80 23.3 6 - I 25 Yes 0 80 7 - I 25 Yes 0 80 8 - I 30 Yes 0 79 At some of the lower loading levels of G there was observed some "sparking" of the graphite during expansion. Presumably, this was the result of the graphite expanding through the rigid polyester, causing some small particles of the resin to be ejected from the sample.
In a few cases, the sparks were hot enough to ignite a sheet of filter paper placed 20 cm below the burning bar.
Example II
Phosphorus in the form of ammonium polyphosphate (APP) was also included in the UPR composition, along with expandable graphite, in the amounts indicated.
The results are shown in Table II.
Table II
Fire Behavior retardant, in fire pph Sample No. G APP Self AfterflameNon-extinguishintime, burnt sec g length, mm 2 - I 5 0 No 365 0 1 - IV 5 5 No 13 73 2 - IV 5 10 Yes 10 75 3 - N 5 15 Yes 0 80 4 - IV 10 0 Yes 0 80 4 - IV 10 5 , Yes 0 80 - IV 10 10 Yes 0 80 6 - IV 10 15 Yes 0 80 7 - IV 0 15 No 40 55 Whereas APP by itself at 15 phr was not self extinguishing and had an afterflame time of 40 seconds, the addition of 5 phr G gave immediate self extinguishing.
No sparks were observed at this concentration of additives. In addition, at a loading level of 10 phr G +
phr APP, the amount of smoke produced was reduced significantly. Thus, the combination of G and APP is distinctly synergistic in this unsaturated polyester resin system.
Example III
Pentabromoethylbenzene [PBEB] with antimony trioxide (Sb203, ATO) were also included in the UPR/expandable graphite composition in the amounts shown below.
The results are shown in Table III.
Table III
Fire Behavior retardant, in Fire pph Sample G PBEB ATO Self AfterflameNon-burnt I No. extinguishingtime, sec length, mm 1 - I 5 0 0 No 36~ 0 1 - V 5 3 2 Yes 0 74 2 - V 5 5 , 2.5 Yes 0 78 3 - V 5 10 3 Yes 7 80 It is apparent that the self extinguishing properties appear at a relatively low concentration of the fire retardants. Zero burning time was found at loadings as low as 5 phr G and 3 phr PBEB with 2 phr ATO.
Expandable graphite flake added to unsaturated polyester resin in the amount of 7 pph or more makes the resin self extinguishing. The use of expandable graphite with ammonium polyphosphate further improves the fire retardant behaviour of UPR: G added at 5 phr with 15 phr APP inhibits burning of the sample while eliminating any afterflame (immediate self extinguishing). Moreover, G and APP together suppress the formation of smoke.
Good fire retardancy can also be obtained by adding expandable graphite to a brominated fire retardant and antimony trioxide. Sparks generated by pieces of the rigid resin ejected by the expansion of the graphite are eliminated with APP or (PBEB + ATO) when applied in a proper ratio.
The above description is intended to enable the person skilled in the art to practice the invention. It is not intended to detail all of the possible variations and modifications which will become apparent to the skilled worker upon reading the description. It is intended, however, that all such modifications and variations be included within the scope of the invention which is defined by the following claims. The claims are intended to cover the indicated elements and steps in any arrangement or sequence which is effective to meet the objectives intended for the invention, unless the context specifically indicates the contrary.
As discussed above, graphite is a crystalline form of carbon comprising atoms covalently bonded in flat layered planes with weaker bonds between the planes.
By treating particles of graphite, such as natural graphite flake, with an intercalant of, e.g. a solution of sulfuric and nitric acid, the crystal structure of the graphite reacts to form a compound of graphite and the intercalant. The treated particles of ~aphite are referred to as "particles of intercalated graphite." Upon exposure to high temperature, the particles of intercalated graphite expand in dimension as much as 80 or more times their original volume in an accordion-like fashion in the "c" direction, i. e. in the direction perpendicular to the crystalline planes of the graphite, thus the particles of intercalated graphite can also be referred to as particles of expandable graphite." Exfoliated graphite particles are vermiform in appearance, and are therefore commonly referred to as worms. The worms act as a barrier to fire, both mechanically and because of their insulative value.
A common method for manufacturing particles of expandable graphite is described by Shane et al. in U.S. Pat. No. 3,404,061, the disclosure of which is incorporated herein by reference. In the typical practice of the Shane et al. method, natural graphite flakes are intercalated by dispersing the flakes in a solution containing e.g., a mixture of nitric and sulfuric acid. The intercalation solution contains oxidizing and other intercalating agents known in the art. Examples include those containing oxidizing agents and oxidizing mixtures, such as solutions containing nitric acid, potassium chlorate, chromic acid, potassium permanganate, potassium chromate, potassium dichromate, perchloric acid, and the like, or mixtures, such as for example, concentrated nitric acid and chlorate, chromic acid and phosphoric acid, sulfuric acid and nitric acid, or mixtures of a strong organic acid, e.g.
trifluoroacetic acid, and a strong oxidizing agent soluble in the organic acid.
In a preferred embodiment, the intercalating agent is a solution of a mixture of sulfuric acid, or sulfuric acid and phosphoric acid, and an oxidizing agent such as nitric acid, perchloric acid, chromic acid, potassium permanganate, hydrogen peroxide, iodic or periodic acids, or the like. Although less preferred, the intercalation solution may contain metal halides such as ferric chloride, and ferric chloride mixed with sulfuric acid, or a halide, such as bromine as a solution of bromine and sulfuric acid or bromine in an organic solvent.
After the flakes are intercalated, any excess solution is drained from the flakes and the flakes are water-washed. The quantity of intercalation solution retained on the flakes after draining may range from 20 to 150 parts of solution by weight per 100 parts by weight of graphite flakes (pph) and more typically about 50 to 120 pph. Alternatively, the quantity of the intercalation solution may be limited to between 10 to 50 parts of solution per hundred parts of graphite by weight (pph) which permits the washing step to be eliminated as taught and described in U.S. Pat. No. 4,895,713, the disclosure of which is also herein incorporated by reference.
When the intercalated graphite is exposed to heat or flame, such as in a fire, the inserted molecules decompose to generate gas. The gas forces apart the carbon layers and the graphite expands. The expanded graphite is a low density, non-burnable, thermal insulation, often referred to as a "worm" because of its curved shape (Figure). For use in the inventive composition, the particles of expandable graphite should preferably expand at temperatures no higher than about 300°C, preferably no higher than about 250°C. Suitable expandable graphites are commercially available from UCAR Graph-Tech, Inc. of Lakewood, Ohio and include UCAR Graph-Tech's GRAFGUARD~ Grade 220 expandable graphite flake and GRAFGUARD~ Grade 160 expandable graphite flake. The principal functional difference between the two grades is onset temperature, that is, the temperature at which expansion begins. For the GRAFGUARD~ Grade 220 expandable graphite flake, expansion begins at 220°C, whereas for GRAFGUARD~ Grade I60 expandable graphite flake, expansion begins at 160°C.
The unsaturated polyester resin (UPR) into which the particles of expandable graphite can be incorporated to form the inventive intumescent composition comprise solutions of unsaturated polyesters (UPs) and similar products in unsaturated monomers that can be cured by radical copolymerization. UPs are composed of glycol and dicarboxylic acid units which include unsaturated copolymerizable acid units and saturated or unsaturated non-copolymerizable acid units. The unsaturated copolymerizable acid units are primarily _7_ derived from malefic acid and fumaric acid residues. The saturated or unsaturated acid units are primarily derived from orthophthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, endomethylenetetrahydrophthalic acid, hexachloro-endomethylenetetrahydrophthalic acid, adipic acid, sebacic acid and tetrabromophthalic acid.
A variety of glycol units can also form a part of the structure of UPs, namely ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, dipropylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, neopentyl glycol, dibromoneopentyl glycol, 2-methyl-1,3-propanediol, chloromethylethylene glycol, 2,2,4-trimethyl-1,3-pentanediol, ethoxylated bisphenol A, propoxylated bisphenol A, and 1,4-cyclohexanedimethanol.
The UP molecules contain terminal hydroxyl and carboxylic groups. They can also be terminated with dicyclopentadiene, i.e. with dihydrodicyclopentadienyl ester groups.
The UPs that are chain terminated with brominated monofunctional units, e.g.
2,3-dibromopropyl residues, are included also. Additionally, oligo (ethylene terephthalate) segments can be incorporated.
UPRs commonly contain mostly styrene as the monomer, although the styrene can be partially or entirely replaced by vinyl monomers, e.g. vinyltoluene or p-t-butylstyrene, acrylic monomers, e.g. methyl methacrylate, ethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate or triethylene glycol dimethacrylate, and allyl esters, e.g.
diallyl phthalate, isophthalate or terephthalate. Allyl ethers, e.g. trimethylolpropane monoallyl ether or trimethylolpropane diallyl ether, can also be used as one of the monomers or built into the molecule of an UP.
So-called vinyl ester resins are also UPRs and are cured and processed in the same way. Vinyl ester resins are solutions of unsaturated esters in the above listed unsaturated monomers, mostly styrene. The unsaturated esters are addition products of methacrylic acid to epoxy groups in epoxy resins, mostly bisphenol A diglycidyl ether type, tetrabromobisphenol A diglycidyl ether and epoxynovolak resin. UPRs, comprising vinyl ester resins, are also used in urethanized form. The urethanization consists of the reaction of _g_ a diisocyanate with a part of hydroxyl groups contained in an UP with the maleate/fumarate unsaturation or in the vinyl esters with the methacrylate unsaturation.
The above described UPRs are cured at ambient temperature using an initiator-accelerator system, such as a hydroperoxide or a ketone peroxide with a cobalt salt or a vanadium compound, or benzoyl peroxide with a tetiary aromatic amine (e.g. N,N-dimethylaniline or N,N-dimethyl-p-toluidine); or at elevated temperatures using peroxy compounds with an elevated decomposition temperature, e.g. benzoyl peroxide or dicumyl peroxide.
Fillers containing UPRs can also be used in the compositions according to this invention, together with expandable graphite and optionally other fire retardants. Powdered fillers, e.g. chalk and talc, and fibrous reinforcing fillers, e.g. glass fiber, juts and sizal can also be included.
In forming the inventive flame retardant compositions, particles of expandable graphite are incorporated into the UPR prior to curing. The graphite particles are included in an amount sufficient to exhibit flame retardancy as compared with the UPR
without graphite.
When incorporated without a synergistic agent, the particles of expandable graphite should be incorporated into the resin at a level of at least about 7 parts by weight graphite per 100 parts by weight of UPR (pph), more preferably at least about 7.5 pph. Most preferably, the particles of expandable graphite are included in the resin composition at a level of at least about 10 pph. Although there is no strict upper limit of the amount of graphite particles to be included, generally, no more than about 25 pph should be included, in order to maintain the mechanical strength of the cured resin composition.
In addition to the particles of expandable graphite and UPRs, the inventive flame retardant compositions can also include other components that act synergistically with the graphite particles to create further flame retardancy for the inventive composition. Such synergistic compositions include ammonium phosphate type compositions like ammonium polyphosphate, which tends to form polyphosphoric acid on oxidation and pyrolysis, and promote charring which reduces burning, and halogen compounds such as chlorine compounds and bromine compounds like pentabromoethylbenzene, optionally with an antimony compound like antimony trioxide or antimony pentoxide. These synergistic compounds can be included at levels of at least about 2 pph, and generally not more than about 15 pph. When the synergistic compounds are included the minimum level of graphite particles can be reduced to about 4 pph in the inventive composition.
In use, the compositions of the present invention can be incorporated in or coated on the surface of the substrate to be protected, and then cured. For instance, the inventive compositions can be coated on strandboard or fibreboard, and provide enhanced fire retardancy to the surfaces; or, the particles of expandable graphite can be incorporated in glass fiber reinforced polyester resin (GRP) products, such as GRP products made by the hand-lay-up method, by spraying etc.
In another embodiment of the invention, particles of expandable graphite can also be added to unsaturated polyester-based resin binders with fibrous and powdered fillers. The best example of these are sheet molding compounds (SMCs) which consist of UPR, chalk, cut glass fibers, a thickener, peroxide initiators, pigments and, optionally, a low-profile additive. Expandable graphite (optionally with other fire retardant additives) may be used to make the compression molded parts fire resistant. In such applications, the expandable graphite can be included at lower levels, as low as 5 parts by weight per 100 parts by weight of UPR or even as low as 3 parts by weight if used in conjunction with a synergistic agent like an ammonium phosphate type compound. An exemplary formulation, in parts by weight: general purpose UPR 100, chalk 120, tert-butyl perbenzoate 1.5, Mg0 (thickener) 4.5, zinc stearate 4.5, cut glass fiber 9.5, expandable graphite particles S or, when ammonium polyphosphate is present at 5 parts by weight, then expandable graphite particles can be present at 3 parts by weight.
The following examples are presented to further illustrate and explain the present invention and should not be viewed as limiting in any regard. Unless otherwise indicated, all parts and percentages are by weight, and are based on the weight of the product at the particular stage in processing indicated.
Example I
The resin employed was Polimal 109 unsaturated polyester resin obtained from Chem. Works "Organika-Sarzyna", Nowa Sarzyna, Poland. The resin is a general-purpose, halogen-free system made of malefic anhydride, phthalic anhydride, 1,2-propylene glycol and styrene. The cold curing system consisted of methylethylketone peroxide and cobalt octoate.
The expandable graphite employed was GRAFGUARD~ 220-80N Expandable Graphite Flake, obtained from UCAR Graph-Tech, Inc. of Lakewood, Ohio. As noted above, in the grade nomenclature, 220 refers to the temperature (in °C) at which the graphite begins to expand; in addition 80 refers to the mesh size of the particles ( 177 micron or larger), and N refers to a neutral flake.
The liquid UPR was mixed with the expandable graphite particles (denoted G), at differing levels, and 1 pph Aerosil 200 (to avoid sedimentation). The components of the curing system consisting of 1.5 pph methylethylketone peroxide (40%) and 0.4 pph cobalt octoate solution (1% Co) were added, and the compositions were cast into 4 mm x 10 mm x 100 mm steel molds. The curing was carried out by holding the cast pieces at 20°C for 24 hours, followed by a postcuring treatment at 80°C for 2 hours.
The fire performance of the bars was tested by heating the samples in a horizontal position using a gas flame for 60 seconds, then monitoring the self extinguishing (afterflame) time (and time to extinguish after application of flame) and the remaining non-burnt length of the bar (up to 80 mm). This test corresponds to the Polish Standard PN-82/C-89023 [see ISO
1210:1992 (E) "Plastics-determination of the burning behaviour of horizontal and vertical specimens in contact with a small-flame ignition source"]. In addition, the Limiting Oxygen Index (LOI) was also determined.
The results are shown in Table I.
Table I
Behavior in fire Sample G, pph No. AfterflameNon-burnt Self extinguishing time, length, LOI, sec mm 1 - I 0 No 280 0 19.5 2 - I 5 No 365 0 21.6 3 - I 7.5 Yes 7 78 4 - I 10 Yes 0 80 23.3 - I 15 Yes 0 80 23.3 6 - I 25 Yes 0 80 7 - I 25 Yes 0 80 8 - I 30 Yes 0 79 At some of the lower loading levels of G there was observed some "sparking" of the graphite during expansion. Presumably, this was the result of the graphite expanding through the rigid polyester, causing some small particles of the resin to be ejected from the sample.
In a few cases, the sparks were hot enough to ignite a sheet of filter paper placed 20 cm below the burning bar.
Example II
Phosphorus in the form of ammonium polyphosphate (APP) was also included in the UPR composition, along with expandable graphite, in the amounts indicated.
The results are shown in Table II.
Table II
Fire Behavior retardant, in fire pph Sample No. G APP Self AfterflameNon-extinguishintime, burnt sec g length, mm 2 - I 5 0 No 365 0 1 - IV 5 5 No 13 73 2 - IV 5 10 Yes 10 75 3 - N 5 15 Yes 0 80 4 - IV 10 0 Yes 0 80 4 - IV 10 5 , Yes 0 80 - IV 10 10 Yes 0 80 6 - IV 10 15 Yes 0 80 7 - IV 0 15 No 40 55 Whereas APP by itself at 15 phr was not self extinguishing and had an afterflame time of 40 seconds, the addition of 5 phr G gave immediate self extinguishing.
No sparks were observed at this concentration of additives. In addition, at a loading level of 10 phr G +
phr APP, the amount of smoke produced was reduced significantly. Thus, the combination of G and APP is distinctly synergistic in this unsaturated polyester resin system.
Example III
Pentabromoethylbenzene [PBEB] with antimony trioxide (Sb203, ATO) were also included in the UPR/expandable graphite composition in the amounts shown below.
The results are shown in Table III.
Table III
Fire Behavior retardant, in Fire pph Sample G PBEB ATO Self AfterflameNon-burnt I No. extinguishingtime, sec length, mm 1 - I 5 0 0 No 36~ 0 1 - V 5 3 2 Yes 0 74 2 - V 5 5 , 2.5 Yes 0 78 3 - V 5 10 3 Yes 7 80 It is apparent that the self extinguishing properties appear at a relatively low concentration of the fire retardants. Zero burning time was found at loadings as low as 5 phr G and 3 phr PBEB with 2 phr ATO.
Expandable graphite flake added to unsaturated polyester resin in the amount of 7 pph or more makes the resin self extinguishing. The use of expandable graphite with ammonium polyphosphate further improves the fire retardant behaviour of UPR: G added at 5 phr with 15 phr APP inhibits burning of the sample while eliminating any afterflame (immediate self extinguishing). Moreover, G and APP together suppress the formation of smoke.
Good fire retardancy can also be obtained by adding expandable graphite to a brominated fire retardant and antimony trioxide. Sparks generated by pieces of the rigid resin ejected by the expansion of the graphite are eliminated with APP or (PBEB + ATO) when applied in a proper ratio.
The above description is intended to enable the person skilled in the art to practice the invention. It is not intended to detail all of the possible variations and modifications which will become apparent to the skilled worker upon reading the description. It is intended, however, that all such modifications and variations be included within the scope of the invention which is defined by the following claims. The claims are intended to cover the indicated elements and steps in any arrangement or sequence which is effective to meet the objectives intended for the invention, unless the context specifically indicates the contrary.
Claims (27)
1. An intumescent composition which comprises a cross-linkable unsaturated polyester resin having particles of expandable graphite incorporated therein.
2. The composition of claim 1 wherein the particles of expandable graphite comprise particles of intercalated graphite which expand when exposed to a temperature of no higher than about 300°C.
3. The composition of claim 2 wherein the particles of expandable graphite are present in the composition at a level of at least about 5 parts by weight of graphite per 100 parts by weight of resin.
4. The composition of claim 1 wherein the cross-linkable unsaturated polyester resin is selected from the group consisting of glycol and dicarboxylic acid units which include unsaturated copolymerizable acid units and saturated or unsaturated non-copolymerizable acid units.
5. The composition of claim 4 wherein the unsaturated copolymerizable acid units comprise maleic acid and fumaric acid residues.
6. The composition of claim 4 wherein the saturated or unsaturated non-copolymerizable acid units comprise derivatives of orthophthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, endomethylenetetrahydrophthalic acid, hexachloroendomethylenetetrahydrophthalic acid, adipic acid, sebacic acid and tetrabromophthalic acid.
7. The composition of claim 1 wherein the cross-linkable unsaturated polyester resin comprises a vinyl ester resin.
8. The composition of claim 1 wherein the cross-linkable unsaturated polyester resin comprises styrene monomers.
9. The composition of claim 1 wherein the cross-linkable unsaturated polyester resin can be cured using an initiator-accelerator system.
10. The composition of claim 1 which further comprises an ammonium phosphate type composition.
11. The composition of claim 10 wherein the ammonium phosphate type composition comprises ammonium polyphosphate.
12. The composition of claim 11 wherein the particles of expandable graphite are present in the composition at a level of at least about 3 parts by weight of graphite per 100 parts by weight of resin and the ammonium polyphosphate is present in the composition at a level of at least about 2 parts by weight per 100 parts by weight of resin.
13. The composition of claim 1 which further comprises a halogen compound.
14. The composition of claim 13 wherein the halogen compound comprises pentabromoethylbenzene.
15. The composition of claim 14 wherein the particles of expandable graphite are present in the composition at a level of at least about 3 parts by weight of graphite per 100 parts by weight of resin and the pentabromoethylbenzene is present in the composition at a level of at least about 2 parts by weight per 100 parts by weight of resin.
16. A method for providing flame retardancy to a substrate, the method comprising coating the substrate with an intumescent composition which comprises a cross-linkable unsaturated polyester resin having particles of expandable graphite incorporated therein, and curing the cross-linkable unsaturated polyester resin.
17. The method of claim 16 wherein the particles of expandable graphite are present in the composition at a level of at least about 7 parts by weight of graphite per 100 parts by weight of resin.
18. The method of claim 16 wherein the cross-linkable unsaturated polyester resin is selected from the group consisting of glycol and dicarboxylic acid units which include unsaturated copolymerizable acid units and saturated or unsaturated non-copolymerizable acid units.
19. The method of claim 18 wherein the unsaturated copolymerizable acid units comprise maleic acid and fumaric acid residues.
20. The method of claim 18 wherein the saturated or unsaturated non-copolymerizable acid units comprise derivatives of orthophthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, endomethylenetetrahydrophthalic acid, hexachloroendomethylenetetrahydrophthalic acid, adipic acid, sebacic acid and tetrabromophthalic acid.
21. The composition of claim 16 wherein the cross-linkable unsaturated polyester resin comprises a vinyl ester resin.
22. The composition of claim 16 wherein the cross-linkable unsaturated polyester resin comprises styrene monomers.
23. The method of claim 16 wherein the cross-linkable unsaturated polyester resin can be cured using an initiator-accelerator system.
24. The method of claim 16 which further comprises an ammonium phosphate type composition.
25. The method of claim 24 wherein the particles of expandable graphite are present in the composition at a level of at least about 4 parts by weight of graphite per 100 parts by weight of resin and the ammonium phosphate type composition is present in the intumescent composition at a level of at least about 2 parts by weight per 100 parts by weight of resin.
26. The method of claim 16 which further comprises a bromine compound.
27. The method of claim 26 wherein the particles of expandable graphite are present in the composition at a level of at least about 4 parts by weight of graphite per 100 parts by weight of resin and the bromine compound is present in the composition at a level of at least about 2 parts by weight per 100 parts by weight of resin.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US49949300A | 2000-02-07 | 2000-02-07 | |
| US09/499,493 | 2000-02-07 |
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| AU (1) | AU1832101A (en) |
| CA (1) | CA2334274A1 (en) |
| GB (1) | GB2359308A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3275914A1 (en) | 2016-07-29 | 2018-01-31 | 3M Innovative Properties Company | Flame retardant adhesive composition |
| EP3275915A1 (en) | 2016-07-29 | 2018-01-31 | 3M Innovative Properties Company | Non-halogeneous fast curing two-component epoxy adhesive with flame retardant properties |
| EP3333211A1 (en) | 2016-12-09 | 2018-06-13 | 3M Innovative Properties Company | Hot/wet resistant low density epoxy compositions |
| EP3666812A1 (en) | 2018-12-13 | 2020-06-17 | 3M Innovative Properties Company | Room temperature stable one-part void filler |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| EP1791919A1 (en) * | 2004-09-20 | 2007-06-06 | 3M Innovative Properties Company | Surface support method |
| DE102007034458A1 (en) * | 2007-07-20 | 2009-01-22 | Evonik Röhm Gmbh | Resin system for intumescent coating with improved metal adhesion |
| US8808850B2 (en) | 2011-10-25 | 2014-08-19 | Arclin | Water resistant intumescent fire retardant coating |
| CN108912939B (en) * | 2017-04-10 | 2020-12-18 | 东北林业大学 | Preparation method and application of transparent intumescent water-based flame-retardant coating |
| CN114874601A (en) * | 2022-05-30 | 2022-08-09 | 南京科工煤炭科学技术研究有限公司 | Unsaturated polyester resin composite material with excellent flame retardant property |
| CN115490922B (en) * | 2022-11-16 | 2023-03-10 | 鲁东大学 | Polyurethane-coated expandable graphite flame retardant and preparation method thereof |
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| CH623068A5 (en) * | 1976-06-18 | 1981-05-15 | Welker Paul Ag | Electroconductive synthetic resin composition, and use thereof for leak monitoring of brickwork or concrete reservoirs coated with synthetic resin or lined with ceramic |
| WO1988002019A1 (en) * | 1986-09-17 | 1988-03-24 | Dixon International Limited | Intumescent material |
| JPH0867771A (en) * | 1994-08-31 | 1996-03-12 | Dainippon Ink & Chem Inc | Flame-retardant molding material |
-
2001
- 2001-02-06 AU AU18321/01A patent/AU1832101A/en not_active Abandoned
- 2001-02-06 GB GB0102956A patent/GB2359308A/en not_active Withdrawn
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3275914A1 (en) | 2016-07-29 | 2018-01-31 | 3M Innovative Properties Company | Flame retardant adhesive composition |
| EP3275915A1 (en) | 2016-07-29 | 2018-01-31 | 3M Innovative Properties Company | Non-halogeneous fast curing two-component epoxy adhesive with flame retardant properties |
| WO2018022496A1 (en) | 2016-07-29 | 2018-02-01 | 3M Innovative Properties Company | Flame retardant adhesive composition |
| WO2018022490A1 (en) | 2016-07-29 | 2018-02-01 | 3M Innovative Properties Company | Non-halogeneous fast curing two-component epoxy adhesive with flame retardant properties |
| EP3333211A1 (en) | 2016-12-09 | 2018-06-13 | 3M Innovative Properties Company | Hot/wet resistant low density epoxy compositions |
| EP3789418A1 (en) | 2016-12-09 | 2021-03-10 | 3M Innovative Properties Company | Hot/wet resistant low density epoxy compositions |
| US11091629B2 (en) | 2016-12-09 | 2021-08-17 | 3M Innovative Properties Company | Hot/wet resistant low density epoxy compositions |
| EP3666812A1 (en) | 2018-12-13 | 2020-06-17 | 3M Innovative Properties Company | Room temperature stable one-part void filler |
| WO2020121196A1 (en) | 2018-12-13 | 2020-06-18 | 3M Innovative Properties Company | Room temperature stable one-part void filler |
Also Published As
| Publication number | Publication date |
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| GB0102956D0 (en) | 2001-03-21 |
| AU1832101A (en) | 2001-08-09 |
| GB2359308A (en) | 2001-08-22 |
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