阅读说明：本技术 膨胀聚丙烯酸组合物 (Expanded polyacrylic acid composition ) 是由 E·普赖斯 C·弗利特伍德 S·希尔顿 G·瓦尼克 于 2019-10-14 设计创作，主要内容包括：设想了一种膨胀组合物,所述膨胀组合物基于对聚丙烯酸(PAA)的改性并包含某些添加剂。此类组合物可掺入环氧树脂和其他基于树脂的涂料中。所述PAA可通过使用一种或多种矿化添加剂来改性以促进焦炭形成。(An intumescent composition based on modification of polyacrylic acid (PAA) and comprising certain additives is envisaged. Such compositions can be incorporated into epoxy resins and other resin-based coatings. The PAA may be modified by the use of one or more mineralisation additives to promote coke formation.)

1. An intumescent coating composition, the intumescent coating composition comprising:

a coating binder system; and

an expansion package with poly (acrylic acid) and PAA modifier.

2. The coating composition of claim 1, wherein the coating binder system comprises between 25.0 wt.% to 75.0 wt.% of at least one resin and at least one curing agent therefor.

3. The coating composition of claim 1 in which the PAA modifier further comprises at least one of the following: poly (vinyl alcohol), poly (vinyl acetate), and combinations thereof.

4. The coating composition of claim 1 in which the PAA modifier is an inorganic mineral.

5. The coating composition of claim 1 in which the PAA modifier comprises at least one metal selected from Al, B, Zr, Cu, Zn, Na, K, Mg, Ca, Sr, Si, and Ti.

6. The coating composition of claim 5, wherein the metal is associated, bound, or complexed with at least one selected from the group consisting of a hydrate, hydroxide, oxide, carbonate, bicarbonate, silicate, sulfate, nitrate, chloride, and phosphate.

7. The coating composition of claim 1 in which the PAA modifier comprises a weak organic acid.

8. The coating composition of claim 7, wherein the weak organic acid is at least one selected from the group consisting of: citric acid, tartaric acid, ascorbic acid, lactic acid, formic acid, acetic acid, oxalic acid, uric acid, malic acid, itaconic acid, and any combination of two or more thereof.

9. The coating composition of claim 1, wherein the poly (acrylic acid) is not neutralized.

10. The coating composition of claim 1, wherein the poly (acrylic acid) is at least partially neutralized.

11. The coating composition of claim 1, wherein the poly (acrylic acid) is at least partially crosslinked.

12. The coating composition of claim 2, wherein the poly (acrylic acid) comprises at least 5.0 wt.% of the coating composition.

13. The coating composition of claim 11, wherein the poly (acrylic acid) comprises no more than 50% by weight of the coating composition.

14. The coating composition of claim 1, wherein the poly (acrylic acid) has a molecular weight of at least 1,000 daltons.

15. The coating composition of claim 1, wherein the poly (acrylic acid) has a molecular weight of at least 2,000 daltons.

16. The coating composition of claim 1, wherein the poly (acrylic acid) has a molecular weight of no more than 1,500,000 daltons.

17. The coating composition of claim 1, wherein the poly (acrylic acid) has a molecular weight of no more than 500,000 daltons.

18. The coating composition of claim 2, wherein the at least one resin is an epoxy resin.

19. The coating composition of claim 1, wherein the coating binder system comprises at least one polymer having a polymer comprising one or more of the following functional groups: epoxy, amine, polyurethane, isocyanate, ester, vinyl ester, amide, thiol, carboxylic acid, acryl, methacryl, anhydride, hydroxyl, alkoxy, and hybrids thereof.

Technical Field

The present invention relates generally to intumescent compositions and more particularly to intumescent coatings incorporating modified or unmodified polyacrylic acid compositions. Polyacrylic acids may be modified with compounds such as mineral acids, metal hydrates, inorganic silicates and/or phosphates, and/or organic substances such as weak organic acids and/or polyvinyl alcohols.

Background

Polyacrylic acid (PAA) is a synthetic high molecular weight polycarboxylic acid (-CH2CH (COOH) -) formed by polymerization of acrylic acid_nA polymer. PAA is used in many applications such as ion exchange resins, binders and detergents. It is also used in fields such as thickeners, dispersants, suspending agents and emulsifiers for use in the pharmaceutical, cosmetic and paint industries.

Over the past fifty years, flame retardant materials have become increasingly important, especially with respect to the manufacture of consumer goods, construction materials, and other commonly used and/or mass produced articles. Because many flame retardant materials incorporate specialized compounds, it is often useful to coat the flame retardant onto a substrate, rather than to construct the article entirely from the flame retardant material itself.

The flame retardant applied to the substrate functions in any combination of a variety of ways to protect the substrate. Some materials will undergo endothermic degradation when exposed to flame or high temperatures, thereby removing heat energy from the substrate. Additionally or alternatively, the flame retardant may generate coke that acts as a thermal barrier to reduce the rate of heat transfer to the substrate. As a final mechanism, some flame retardant materials release compounds when exposed to heat in order to dilute flammable reactants (e.g., inert or non-flammable gases) or scavenge free radicals generated by the burning material and slow flame growth.

Intumescent coatings are a form of passive fire protection, usually applied as a thin film, that expands many times its original thickness to form an insulating coke. This acts as a barrier between the flame and the substrate (such as structural steel). Intumescent coatings are generally classified according to the type of flame (e.g., a cellulosic or hydrocarbon fuel flame) for which they are designed to provide protection.

Intumescent coatings are particularly useful for application to structural steel (e.g., beams, columns, panels, etc.) and other metal structural components to prevent collapse and/or structural damage. They are also applied to partitions, ceiling panels and fire walls of structures as a further protection for occupants during a fire event.

Conventional intumescent coatings consist of a polymeric binder, an acid source, a charring agent and a blowing agent.

When the intumescent coating is exposed to flame or excessive heat, the acid source decomposes to provide the acid. The charring agent or char-forming agent (carbon source) reacts with the acid to form carbonaceous coke while the blowing agent degrades to produce a non-flammable gas (e.g., ammonia). The evolved gases are used to produce expanded carbonaceous char/foam. The thick, porous, highly insulating, non-flammable solid foam protects the substrate it covers from incident heat.

Cellulose fuel flames are typical for modern commercial and infrastructure projects in building environments, typically for building applications with exposed structural steel products inside and outside. The cellulose standard fire test curve (british standard BS476-20 cellulose) reached 500 ℃ in about 3 minutes and rose to over 1000 ℃ (i.e., 1832 ° f) in 90 minutes.

Hydrocarbon fuel flames are typical for oil and gas installations. The hydrocarbon standard fire test curve (BS476-20 hydrocarbon) reached 500 ℃ in 1 minute and rose to over 1000 ℃ (i.e., 1832 ° f) in about 8 minutes.

The hydrocarbon fuel injection flame is a highly corrosive, extremely turbulent flame (ISO 22899-1) and immediately heats upTo 1100 ℃. A flame of this nature experiences approximately 250Kw/m²Heat flux of (2).

The intumescent coating needs to produce a tough, hard, strong and dense coke foam that is tough enough to resist the extreme corrosiveness of hydrocarbon fuel injection flames, and to maintain adhesion to the substrate (in this case structural steel). Boric acid is commonly used in intumescent coatings to resist hydrocarbon fuel jet flames as it helps to produce strong boron oxide ceramic type coke with good adhesion.

Boric acid, when used, has four main functions in intumescent coatings:

(1) endothermic cooling-boric acid dehydrates at 100 ℃ to form metaboric acid. This cooling effect helps to resist the intense heat of the flame. The most critical aspect of the barrier test is to ensure that the protected steel does not exceed about 160 ℃ (140 ℃ above ambient starting temperature) within 1 hour, to ensure human survival inside the steel structure and/or to prevent ignition of flammable materials that may be present on the non-flame side, as required by IMO a754(18) E approval. This in turn provides cooling very early in the flame, as it endothermically releases water at about 100 ℃.

(2) Acid functionality-as heat is increased, the metaboric acid continuously reacts with the resin binder (typically epoxy/polyamide) to produce carbon coke. This acid-catalyzed degradation of epoxy resins when heated generates coke residues.

(3) Boric acid acts synergistically with other swelling actives to lower the degradation temperature. This also has a positive effect on the melt viscosity. At temperatures above 250 c, more dehydration occurs, forming a hard mineral glass-boron oxide.

(4) Vitrified-boron oxide crystals begin to decompose at 300 ℃. These crystals melt and continue to react with other key components such as ammonium polyphosphate, forming extremely hard ceramic coke consisting of borophosphate. A series of suboxides were also produced, which partially melted until complete fusion was achieved at 700 ℃. For example, boron trioxide, a glassy solid, can be produced to act as a fire barrier.

Boric acid is currently classified by the european chemical authority (ECHA) as a class 2 reproductive toxin. It is also on the ECHA SVHC (list of substances of high interest) and may move to the ECHA authorization list. This would mean disabling its use unless authorization is requested and granted. Boric acid is a component of the epoxy intumescent coating and allows the product to achieve effective fire spray resistance and barrier fire resistance on steel.

When removing boric acid, intumescent coatings typically rely on boron additives, metal oxides, expanded graphite, reinforcing agents (such as carbon fibers), and/or other coke reinforcing compounds to establish the necessary strong coke structure to resist the jet flame. These materials may limit coke expansion, compromising thermal protection, while possibly having their own environmental and/or health concerns. The endothermic cooling effect of boric acid (particularly that required for steel bulkhead and ceiling protection) is also typically lost. Carbon fibers can also be difficult to incorporate into paint during manufacturing, resulting in a highly viscous product.

Currently, Jotachar JF750, available from zolndon corporation, juvenin, sandeffjord, Norway, and turnera, Norway, is one type of commercially available epoxy resin intumescent coating. Chartek 7 from Akzo Nobel corporation (Akzo Nobel, Amsterdam, the Netherlands) of Amsterdam, the Netherlands, and Firetex M90/02 from shearwin Williams, Cleveland, Ohio, USA, are other examples of epoxy intumescent coatings. Additional intumescent materials and/or flame retardant products may be sold by each of these respective units or other units under these or other trade names.

U.S. patent publication 2016/0145466 discloses intumescent coatings suitable for protecting substrates against hydrocarbon flames, such as jet flames. The composition comprises a thermosetting polymer, a curing agent, a phosphoric and/or sulfonic acid, a metal or metalloid ion, and an amine-functionalized blowing agent. Thus, the intumescent coating may be used without a supporting mesh.

U.S. patent publication 2016/0152841 contemplates similar types of intumescent coatings. Here, boric acid may be used in addition to phosphoric/sulfonic acid, and melamine and isocyanurate are also included. No metal or metalloid ions are required.

U.S. patent publication 2016/0145446 describes further iterations of this comparison with the documents cited above. In this case, the intumescent material comprises a thermosetting polymer, a curing agent, phosphoric and/or sulphonic acid, metal or metalloid ions, and a urea, dicyanamide and/or melamine based blowing agent.

U.S. patent publication 2016/0160059 provides intumescent coatings based on organic polymers, foamable materials and additives that provide a combination of two different sources of metal/metalloid ions. Hydroxy-functional polysiloxanes are claimed for this particular use and specific types of metal atoms are described.

In yet another example, U.S. patent publication 2015/0159368 describes a liquid intumescent coating having at least one ethylenically unsaturated monomeric polymer resin. The resin is cured by free radical polymerization which is adhesively bonded to the reinforcing structure, such as an inorganic fabric.

Finally, Edward Weil, along with academic publications published by the university of New York college of science and technology, and by the Caroline Gerard, Gaelle Fontaine, and Serge Bourbigot groups, describes various fire-blocking materials that may be intumescent or non-intumescent in nature. In the same way, Jimenez, Duquesene and Bourbigot describe the mechanism of action of boric acid and coated ammonium polyphosphate as flame retardants.

Drawings

The operation of the present invention may be better understood by reference to the following description of specific embodiments. These drawings form part of the specification, and any information on/in the drawings is to be read literally (i.e., the actual specified value) and relatively (e.g., the ratio of the respective dimensions of the parts). In the same manner, the relative positioning and relationship of the components as illustrated in the figures, as well as their function, shape, size and appearance, may further inform certain aspects of the present invention as if fully rewritten herein. Unless otherwise noted, all dimensions in the drawings are relative to inches, and any printed information on/in the drawings forms part of this written disclosure.

In the drawings and the accompanying drawings, all of which are incorporated as part of the disclosure:

FIG. 1 shows the known reaction mechanism of polyacrylic acid (PAA) with respect to (A) dehydration, (B) decarboxylation, and (C) chain scission.

Fig. 2A is a thermogravimetric analysis (TGA) of PAA in air, showing the change in weight with temperature, including the endothermic reaction after 190 ℃. The final residual solids were less than 1% (low ash value) at 600 ℃. The TGA graph shows the decrease in weight percent (% by weight) with temperature and the derivative weight change (%/deg.c).

Figure 2B is a thermogravimetric analysis in air of an exemplary PAA compound fully neutralized (with 0.5M NaOH) showing weight as a function of temperature, indicating that the final residual solids had increased to > 50% (increasing low ash value) at 600 ℃.

Figure 2C is a thermogravimetric analysis in air showing the weight as a function of temperature of trisodium citrate dihydrate with sodium metasilicate and PAA-Na (fully neutralized with 0.5M NaOH) at a weight ratio of 25:25:50, respectively. The final residual solids was about 65% at 600 ℃.

Fig. 3A is a photograph of PAA mixed with inorganic compounds and citric acid in an expanded paint after a propane spray gun test. This forms a foam coke.

Figure 5a is a photograph of a PAA gel heated to 300 ℃.

Figure 5b is a photograph of PAA swelled with epoxy/amine.

FIG. 6 is a graph of the reaction mixture with ZnCl before and after heating to 600 deg.C₂Photographs of mixed PAAs.

Figure 7 is a comparative set of TGA profiles for linear PAA (left) and NaOH-treated linear PAA (PAA-Na) (right).

Figure 8A is a TGA plot for PAA; FIG. 8B is PAA-COOH/Na⁺TGA profile of (a); FIG. 8C is PAA-complete Na⁺TGA profile of (a); and FIG. 8D is PAA-Ca²⁺TGA profile of (a).

Figure 9 is a series of TGA plots for PAA cross-linked or in-line with sodium metasilicate or citric acid, as shown by the legend below each plot.

Fig. 10 shows a series of photographs of the burn test, which correspond to the material disclosed in fig. 9 (including the legend shown below each of the pictures).

FIG. 11A is a TGA profile of TCD; FIG. 11B is a TGA plot of TCD: SM (50: 50); and FIG. 11C is a TGA plot of TCD: SM: PAA-Na (25:25: 50).

FIG. 12A is a TGA profile of CA; FIG. 12B is a TGA plot of CA: SM (50: 50); and FIG. 12C is a TGA plot of CA: SM: PAA-Na (25:25: 50).

Fig. 13A-13C are TGA plots of additional embodiments, as shown by the legend for each figure.

Fig. 14 shows the results of performing micro-scale combustion calorimetry on various salt forms of PAA.

Figure 15 is a photograph of coke after Meker fire test (as envisioned in table 3) based on PAA modified with inorganic compounds and weak acids.

Fig. 16 is a photograph of exemplary PAA coatings before (left) and after (right) a propane spray gun test.

Figure 17 is a photograph of a Meker test performed on an exemplary PAA coating.

Fig. 18 depicts conditions for cone heater results for an exemplary boric acid-free experimental formulation comprising PAA and shows photographs of these results.

Fig. 19 is a graph comparing results of cone calorimetry performed on a boric acid-containing coating and a PAA-containing coating.

Fig. 20A to 20F show the coke structure produced by performing the Meker test on formulations 1, 2, 3, 4 and 5 in table 4, while fig. 20F shows the coke structure obtained in a commercially available boron-containing acid formulation.

Fig. 21 is a time versus temperature curve used to quantify the performance of certain intumescent coatings relative to an intumescent paint comprising PAA.

Detailed Description

With particular reference to the appended claims, drawings and description, all of which disclose elements of the present invention. While specific embodiments are identified, it should be understood that elements from one described aspect may be combined with those from a single identified aspect. In the same manner, one of ordinary skill will have the necessary understanding of common processes, components, and methods, and this description is intended to cover and disclose such common aspects, even if not explicitly identified herein.

As used herein, the words "example" and "exemplary" mean an instance or illustration. The word "exemplary" or "exemplary" does not indicate a critical or preferred aspect or embodiment. Unless the context indicates otherwise, the word "or" is intended to be inclusive and not exclusive. For example, the phrase "A employs B or C" includes any inclusive permutation (e.g., A employs B; A employs C; or A employs both B and C). In addition, the articles "a" and "an" are generally intended to mean "one or more" unless the context indicates otherwise.

Table 1 shows the prominent acronyms used throughout this disclosure.

TABLE 1 acronyms used in this disclosure。

Compound (I)	Abbreviations
		Poly (acrylic acid) (untreated)	PAA
Poly (acrylic acid) (treated with NAOH)	PAA-Na
		Sodium metasilicate	SM
Trisodium citrate dihydrate	TCD
		Citric acid	CA
Polyvinyl alcohol	PVOH

All of the above patent publications are incorporated by reference as if fully rewritten herein. In particular, these disclosures provide detailed information about the prior art and the types of resins, curing agents, adhesives, and blowing agents that may be used in connection with the aspects of the invention described and/or claimed below.

Poly (acrylic acid) (PAA) is a weak polyacid (pKa of about 4.5) commonly used in consumer products. PAA has an inherently low Heat Release (HRC) and Total Heat Release (THR) relative to other polymeric materials.

PAA is in powder form and is easy to incorporate and can result in a lower viscosity product compared to products with carbon fibers. This, in turn, makes PAA-based products easier to apply due to the omission of carbon fibers and gives excellent aesthetic appearance.

The present inventors have found that compounds based on poly (acrylic acid) (PAA) modified with certain PAA modifying compounds exhibit swelling behavior that is applicable to hydrocarbon fuel flames. These PAA modifiers may comprise and introduce multivalent ions, such as (but not limited to) Ca, into PAA²⁺Or Na⁺. Additionally, these PAA modifiers may be selected from weak organic acids, mineralizing additives, polyvinyl alcohol, polyvinyl acetate, and/or inorganic components such as silicates, chlorides, carbonates, and hydrates.

Such modified PAA used as part of an intumescent package (i.e., greater than 5% by weight of the total formulation) tends to control coke expansion without the need for fiber or boron additives. The formed coke can be modified by adding different amounts/types of PAA mixed with inorganic compounds and/or weak acids or PVOH to provide structural similarity to the expanded paint with boric acid. It has been found that PAA modified with and without inorganic compounds releases water at temperatures >120 ℃, providing an endothermic response.

Thus, the modified PAA may provide four main functions required in intumescent coatings: 1) cooling very early in the flame due to the endothermic release of water at 120 ℃; 2) acid-catalyzed degradation of the epoxy resin upon heating; 3) synergistic reaction with other swelling active ingredients; and 4) the production of hard, strong, foamed coke that can act as a fire barrier.

Referring to the drawings, these reactions are shown. In fig. 1, the dehydration step (a) is initiated at a temperature above l40 ℃ to form temporary carboxylated ring structures within the PAA chains, where the water formed supports the endothermic response. In particular, the water and carbon dioxide produced may cool the flame and dilute the volatile fuel and oxygen necessary for combustion. Next, as seen in step (b), decarboxylation occurs within the backbone, which then undergoes chain scission as shown in step (c). The remainder of the chain provides the backbone for charring, while the volatiles released during these reactions can serve as blowing agents into the carbon matrix.

Table 2 shows the known previously reported literature values for PAA degradation and indicates an endothermic reaction.

Table 2: temperature of PAA degradation

With reference to the above discussion, the present inventors sought materials that meet at least one of the following criteria: endothermically releasing water at above 100 ℃ (more preferably between 120 ℃ and 160 ℃), being able to catalyze coke formation before reaching the vitrification temperature, and being able to vitrify the coke.

PAA decomposition is accompanied by three main processes: 1) dehydration (endothermic release of carbon dioxide and water that can cool the flame), 2) decarboxylation and 3) main chain reactions with some coke formation. In other words, PAA may function in a similar manner to boric acid. PAA also has an inherently low Heat Release (HRC) and Total Heat Release (THR) relative to other polymeric materials. Further, the structure of PAA is a polymer backbone with carboxylic acid groups. The carbon backbone should be suitable for charring. The release of volatiles will then possibly blow the carbon matrix foam (fig. 5A-photograph of PAA gel heated to 300 ℃, and fig. 5 b-photograph of PAA expanded in epoxy/amine system).

The acid groups may also provide for acid catalyzed dehydration of the epoxy/amine (or polymer). Thus, the present inventors identified PAA and modified PAA as potentially promising swelling additives.

PAA is a relatively low cost material used in many applications including superabsorbents (as an alkali metal salt form), ophthalmic drug delivery systems, emulsion thickeners, emulsion polymers, and pigment dispersants, where the emulsion and pigment dispersion functions are employed in a variety of chemical coating applications. However, PAA itself has received very limited attention as an additive to impart fire resistance to epoxy and other polymer systems, which necessarily requires certain modifications and other unique considerations (e.g., total mass provided to the formulation, molecular weight of PAA, etc.) that are not covered only by the aforementioned prior uses.

While the present inventors are aware of the fact that PAA has been used in layer-by-layer deposition techniques for flame retardant materials, PAA only traps clay platelets (and/or other similar substances) between layers in these applications. Thus, this method requires multiple coating applications. In addition, the resulting layered film is much thinner (typically on the nanometer scale compared to the 10+ micron coating contemplated herein) and PAA does not act as an expanding agent.

Another previous example of PAA found in expanded compositions can be found in us patent 6,207,085. Here, expandable graphite is used in combination with a flame retardant based on an alkyl diamine phosphate. Here, a resin emulsion having a Tg of less than-40 ℃ is formed, and the resin emulsion preferably contains an inorganic filler such as clay. The resin itself may comprise polyvinyl acetate, polyacrylic silicone, or styrene-butadiene latex, but the resin does not contribute to the expansion aspect of the composition (which comes from the expanded graphite and the alkyl diamine phosphate). In U.S. patent 5,968,669 and international patent publication WO 2011/60832, PAA (in the form of polyacrylic acid latex and PAA alkyl or aryl esters, respectively) is provided in combination with expanded graphite and various other intumescent packaging in a resin. Finally, in international patent publication WO 2001/005886, the intumescent composition relies on a coke forming agent, a polymeric binder, a crack control agent, and an optional surfactant which may include PAA as a dispersant and is therefore provided in relatively small amounts (<3.0 wt%) in a water-based coating system.

To understand why expanded graphite appears repeatedly in these prior uses, it should be understood that PAA has a low coke yield (low ash value). Thus, the inability of PAA to form a thermally protective coke barrier may be a reason why PAA was not considered useful as an expander prior to this discovery.

The inventors have found that the ability of modified PAA to coordinate to a variety of ions significantly alters its residual coke yield. Various inorganic compounds and/or metals associated with or incorporated as hydrates, hydroxides, silicates, phosphates, etc. may be incorporated with PAA (and/or in the coating formulation itself) to promote coke formation, as well as the addition and use of weak organic acids (i.e., those having pKa values between 1.0 and 6.7 and pH in the range of 1.0 to 6.5). In addition, it has been found that polyvinyl alcohol and/or polyvinyl acetate can also promote coke formation. As such, by providing any of these modified forms of PAA and derivatives thereof, it is possible to rely on PAA as a char-forming agent, as well as to deliver other functions previously associated with boron-based additives.

Various studies were performed on PAA and its derivatives, as described in more detail below. In particular, PAA may be neutralized, partially neutralized, or unneutralized, as well as crosslinked, partially crosslinked, or non-crosslinked.

Additionally or alternatively, the inventors incorporate inorganic compounds into various coatings or in combination with PAA into various coatings. These inorganic compounds can include, but are not limited to, metals (e.g., Al, B, Zr, Cu, Zn, Na, K, Mg, Ca, Sr, Si, Ti) associated with or incorporated as hydrates, hydroxides (e.g., NaoH or CaoH), oxides, bicarbonates, silicates, carbonates, sulfates, nitrates, phosphates, chlorides, and the like, as well as complexes thereof.

Metal carbonates, metal bicarbonates, metal hydrates, metal phosphates, metal chlorides, metal sulfates, metal silicates, metal nitrates and metal borates are compounds in which the metal atom is bonded to a hydrate, hydroxide, oxide, bicarbonate, silicate, carbonate, sulfate, nitrate, phosphate and chloride, respectively. In these compounds, the metal ion is bonded in proportion to the functionalizing ions listed above to balance the charge on the metal ion. They may contain one or more different types of metal ions. These compounds are known to the person skilled in the art. For example, the source of the metal hydrate is trisodium citrate dihydrate and the source of the metal silicate is sodium metasilicate.

The source of the metal/metalloid atoms can also be a complex comprising metal ions bonded to one or more of the following counterions: hydrate ions, hydroxide ions, carbonate ions, silicate ions, bicarbonate ions, chloride ions, phosphate ions, sulfate ions, nitrate ions, and borate ions. Preferred sources of metal ions for use in the present invention include, for example, sodium metasilicate and trisodium citrate dihydrate.

Hydrates can be, for example, monofunctional, difunctional, trifunctional, tetrafunctional, pentafunctional, hexafunctional, heptafunctional, octafunctional, nonafunctional, and decafunctional.

To increase the stiffness of the expanded structure and to increase the other synergistic effects of PAA, the inventors mixed PAA with inorganic compounds to neutralize it with various ions. Figure 6 shows coke formation of zinc neutralized PAA upon heating.

In addition, incorporation of weak acids such as citric acid, tartaric acid, ascorbic acid, lactic acid, formic acid, acetic acid, oxalic acid, uric acid, malic acid, itaconic acid, and the like, exhibits improved swelling characteristics.

Resin-based (with curing agents where appropriate) coatings are of particular interest, and the materials and methods described herein can be incorporated into any number of other resins and coating systems, including epoxy resins, amines, amides, acrylates, vinyl ester silicones, polyurethanes, polysiloxanes, polyureas, ketones, unsaturated polyesters, acrylates, vinyl acetates, methacrylates, and derivatives thereof, and the like. The resin may be thermoplastic or thermosetting.

The organic thermosetting polymer may be one organic thermosetting polymer (including hybrids) or a mixture of more than one different organic thermosetting polymer (including hybrids). The organic thermosetting polymer may include, but is not limited to, one or more of the following functional groups: epoxy, amine, polyurethane, isocyanate, ester, vinyl ester, amide, thiol, carboxylic acid, acryl, methacryl, anhydride, hydroxyl, and alkoxy groups.

The thermosetting polymer may also be an ethylenically unsaturated acrylate peroxide or a UV curable resin such as methyl methacrylate.

The thermoplastic polymer may be based on monomers such as vinyl acetate, vinyl toluene, styrene, and other vinyl and acrylic moieties.

All coatings contemplated herein are typically more than 5 microns thick. The dry film thickness of the intumescent coating layer, when applied to a substrate, is typically between 1mm (millimeters) and 40 mm. Dry film thickness can be measured using an Elcometer dry film thickness meter.

It will be appreciated that values outside of these minimum and maximum ranges are also possible, depending on the application, and that the values described herein are merely exemplary preferred and/or possible ranges. Any and every combination of the minimum and maximum limits stated individually is contemplated.

The compositions of the invention herein are well suited for coating on steel substrates, and in particular structural steel beams and columns and other load bearing or non-load bearing parts. To the extent that the expansion agent is incorporated with the epoxy resin or other thermosetting or thermoplastic resin and the curing agent, the formulations of the present invention can be used as a direct replacement for previously known structural coatings.

As another example, past examples of incorporating meth (acrylic acid) and/or poly (acrylamide) should not be confused with poly (acrylic acid) and its derivatives, as contemplated in this disclosure. While these other materials may be useful in flame retardant coatings, they may have different (and less favorable) heat release amounts, meaning that they release different amounts of heat when they are burned compared to the PAA compounds of the present invention.

It is envisaged that the modified PAA (as envisaged herein) may also be used as a coolant and/or blowing agent etc and results in a hard strong foamed coke which can act as a fire barrier, especially for high temperature hydrocarbon type flames.

In this regard, PAA does not need to incorporate or rely on matrix materials such as carbon fibers. Indeed, PAA (in most of its various forms) is suitable, due to its powder form, for lower viscosity formulations which are easier to apply and/or which impart an excellent aesthetic appearance.

Without being bound by any particular theory or mode of operation, the present inventors realized that modified PAA will function as an excellent expanding material due to its tertiary degradation. In the first step, occurring in most of the forms tested above 140 ℃ (and in some of the examples below at about 170 ℃), the two carboxylic acid groups come together to form an anhydride ring, in the process releasing water (coolant). Subsequently, a second degradation mode starts at 200 ℃ and corresponds to decarboxylation via cleavage of the anhydride ring, leading to CO₂(blowing agent) release. Finally, at higher temperatures, polymer backbone scission occurs, breaking the polymer chains along the backbone. It should be noted that the only difference between linear PAA and its lightly crosslinked counterpart is the ease of handling the solid form and that the crosslinked samples are more synergistic. With respect to thermal stability, lightly crosslinked and linear sodium treated PAA samples have negligible differences.

The present inventorsDiscovery, with Ca (OH)₂Or NaOH-treated PAA, any form of which enhances the performance relative to coke formation and improves the expansion characteristics.

For the avoidance of doubt, the features provided in the above description may be combined in any order. The drawings and the specific embodiments described herein are intended to illustrate the invention and should not be construed as limiting the scope of the invention in any way.

For example, as described above, fig. 2A-2C show other TGA profiles. More significantly, fig. 7 shows that treating linear PAA with NaOH (metal hydroxide) increases the residual solids on PAA.

When performing degradation analysis (e.g., fig. 8A-8D), interesting qualities of PAA were observed as a function of salt selection. First, regardless of the choice of ion, coordination between the carboxylate and ion inhibits the formation of the anhydride ring (and subsequent decarboxylation). This degradation is replaced by backbone chain scission that occurs silently at higher temperatures. Next, the temperature at which the main chain scission occurs varies depending on the selection of the complex ion. As shown by the results below, the presence of the carboxylic acid moiety and carboxylate salt appears to coordinate with the sodium (and other) ions. Such as Zn, Ca, Al, Na, Cl, Cu, etc.

Figure 9 shows different degradation curves for PAA in linear and cross-linked with silicate ions (from sodium metasilicate) and citrate ions (from citric acid). In turn, fig. 10 shows a photograph of a foamed coke of PAA modified with sodium metasilicate or citric acid. This indicates that the citrate ion has improved swelling characteristics.

A number of salts were studied, but four were finally selected for further study: 1) citric Acid (CA), 2) Trisodium Citrate Dihydrate (TCD), 3) Sodium Metasilicate (SM), and 4) calcium silicate (CaSiO). The CA and its salt counterpart (TCD) are selected based on their natural abundance and their ability to act as a source of acid in intumescent coatings. Sodium metasilicate is chosen for its inherent fire retardant ability. Finally, calcium silicate is selected based on the additional stiffness provided by its incorporation.

In view of these characteristics, the TGA data obtained after blending various minerals with PAA samples gave particularly interesting results. Two mixtures were tested, one incorporating CA and the other incorporating TCD. Initially, TGA was performed for each mixture. Subsequently, SM was added to each mixture at a 50:50 wt% ratio and tested again. Finally, PAA-Na was added to the sample to yield a ratio of 25:25:50 wt% CA (or TCD): SM is PAA-Na. Blocking any chemical interaction between the various blend components would be expected to produce a superposition of the TGA of each additive. However, as shown in FIGS. 11a-c and 12a-c, this is not the case.

FIGS. 11A-11C show a series of TGA plots for A) TCD, B) TCD: SM (50:50), and C) TCD: SM: PAA-Na (25:25: 50).

FIGS. 12A-12C show a series of TGA plots for A) CA, B) CA: SM (50:50), and C) CA: SM: PAA-Na (25:25: 50).

In view of these results, the inventors believe that several mechanisms may be in play. First, it is assumed that ion exchange from the neutralized PAA sample to other molecules in the melt occurs upon heating (whereas, it is assumed that ion exchange from other molecules in the melt to the neutralized PAA sample occurs upon heating). The kinetics in the melt are clearly the fastest for chemical reactions and the energy barrier for these interactions is almost negligible in view of the thermal energy supplied to the system.

Another interesting direction of investigation arising from these TGA problems relates to the crystallization of water. At the TGA of trisodium citrate dihydrate (fig. 11a), a lack of water peak at about 100 ℃ is observed, which would otherwise correspond to the volatilization of the dihydrate. Instead, a peak was observed at about 190 ℃. This means that the two water molecules are not free water but are incorporated in the crystal structure of the molecule.

Structurally, there are two differences between CA and TCD. First, all carboxylic acid moieties of TCD are neutralized by sodium. Second, CA is anhydrous and TCD is dihydrate. In terms of thermal degradation, CA shows one major degradation peak around 200 ℃, corresponding to intermolecular anhydride ring formation and subsequent decarboxylation via ring cleavage.

TCD, which is very similar to PAA and its neutralized form, shows significantly different degradation than its unneutralized analog. Two major degradation events were observed, one at 190 ℃ and the other at 325 ℃. The latter degradation event is due to the degradation of secondary alcohols. However, the identification of events at 190 ℃ is more important. No degradation events were observed at 100 ℃ that would correspond to volatilization of both hydrates, which resulted in the assumption that water release occurred at this higher temperature. It is also assumed that this delayed release is due to the fact that the dihydrate in TCD is crystalline water. The water embedded in the crystal structure is sterically hindered and cannot be volatilized as usual at 100 ℃.

In contrast, SM does not undergo similar types of degradation. Structurally, SM is a polymeric structure consisting of a silicon-oxygen backbone with pendant oxygen groups coordinated to sodium. SM, which is commonly used in flame retardant applications, is known to form large oxide structures when heated. Therefore, it can also be selected as a suitable mineralizing additive.

While attention is directed to the specific mineralization additives described above, it is to be understood that a variety of such additives may be used. As additional examples, other hydrates, carbonates, chlorides, nitrates, carbonates, silicates, and/or phosphates may be employed, particularly those having low cost and/or similar characteristics to the other materials described herein. Furthermore, materials having similar characteristics and which are compatible with PAA and/or formulations of the coating system should be particularly useful. Additionally or alternatively, structural and chemical analogs and/or derivatives of the above materials are also expressly contemplated.

Notably, with respect to the use of citric acid or other potentially reactive compositions, it is understood that these materials should be incorporated into the formulation in a manner that avoids or greatly reduces any reaction between the additives and the other constituent components of the formulation.

High speed, high temperature flame resistance tests were conducted in accordance with the teachings provided by BS476-20 and/or ASTM E1529, and various related methods covered or disclosed by these standards. Both Trisodium Citrate Dihydrate (TCD) and Citric Acid (CA) modified PAA produced increased swelling compared to PAA alone.

However, Sodium Metasilicate (SM) produces tougher coke but provides limited expansion. Based on these conclusions, both silicate and citrate were selected to be blended with PAA samples for low to medium concentration epoxy testing.

TGA of other inorganic/PAA mixtures were also tested during the course of this study as shown in figures 13A to 13C.

Additional tests were performed in order to more specifically understand the heat release profile of the reactions and potential materials under consideration. For example, Microscale Combustion Calorimetry (MCC) utilizes milligram-scale materials to measure oxygen consumption as a function of heating rate. Thus, the rate of thermal release (HRR), peak rate of thermal release (PHRR), and total thermal release (THR) can be quantified to elucidate the basic properties of PAA and the derivatives of interest.

Fig. 14 shows the results of performing micro-scale combustion calorimetry on various salt forms of PAA. Interestingly, these HRR curves vary significantly with ion selection. For purposes of explanation, the x-axis may be interchanged with temperature when the heating rate is 1 ℃/s. Lin-PAA-COOH exhibited a broad rate of heat release at 300 seconds, which may correspond to the heat release caused by anhydride ring cleavage. Upon salination with sodium, two significant changes were observed. First, the PHRR rate increased 3-fold relative to Lin-PAA-COOH. Second, the THR decreases by about 20%. From monovalent to divalent ions, calcium also uniquely functions. Coordination with calcium reduced the total heat release by approximately 45% while maintaining a PHRR comparable to Lin-PAA-COOH.

The results in table 2 above show that there is an increase in the expansion and coke hardness after addition of PAA-Na and various inorganic compounds. The results also show an increase in expansion and coke hardness after addition of citric acid. PVOH also provides improved coke hardness.

The epoxy-based base intumescent formulation containing PAA additive, ammonium polyphosphate (APP) and melamine was subjected to the laboratory Meker test shown in table 3 and described below. In each of these formulations, at least twice the amount of APP (by weight) is provided compared to the other components, while the PAA-based additive and melamine are added in relatively similar weight ratio amounts.

Table 3: for containing epoxy resin and polyaminoAmides, ammonium polyphosphates (APP) and melamine and different inorganic compounds Laboratory Meker test results for formulations with and without citric acid, including additional testing with addition of PVOH

An epoxy-based intumescent material was prepared comprising sodium metasilicate and PAA treated with citric acid and sodium (25:25:50 wt% ratio). The coke expanded 4 times its own volume after the fire test. The char-burned coke foam is hard and tough (as shown in fig. 15) and may be suitable for use in hydrocarbon expansion flames and jet flames.

Finally, polyvinyl alcohol (PVOH) improves the coke toughness of expanded paints comprising PAA. Further synergy may be achieved when PAA, PVOH, poly (ethylene-vinyl acetate) (PEVAC) and polyvinyl acetate (PVAC) and their derivatives are combined.

In all of the foregoing aspects, the intumescent composition is produced without reliance on expanded graphite or additives such as boric acid. This approach results in a more cost effective and environmentally friendly formulation and represents an improvement over the existing methods described herein. However, the expansion properties of the compositions of the present invention contemplated herein can be enhanced by providing reduced amounts of these materials.

As shown in the examples below, the PAA and/or modified PAA should be provided in an amount of at least 5.0 wt%, at least 7.5 wt%, or at least 10 wt% compared to the entire composition. The compositions of the invention may comprise as much as 20 wt%, 25 wt% or even 50 wt% or more of PAA and/or modified PAA (relative to the total composition). When PAA is incorporated as part of an expanded package, amounts as little as 0.5 wt% can still deliver some of the marginal benefits contemplated herein, but its low cost and the benefits inform the minimum above.

Thermoplastic and/or thermosetting resins may be provided as part of the coating binder system. In particular, epoxy resins, polyamides, polyaminoamides, polyamines, polyurethanes, polyethers, acrylics, acrylates, unsaturated polyesters, vinyl esters, polysiloxanes and silicones may be used. One area of particular interest is in epoxy-based coating binder systems. Generally, the coating binder system will form the bulk of the composition of the present invention, typically between about 25.0% to 75.0% by weight. A variety of resins, curing agents, and other additives may be provided to enhance certain desired attributes of the adhesive system, as is known in the art. The remainder of the composition as a whole will include the expansion package, including any combination of the above elements. Other additives and modifiers may also be included as part of the remainder.

It should be understood that a wide range of PAAs are available and that PAA materials having a molecular weight of at least 1,000 daltons, at least 2,000 daltons, or at least 7,000 daltons should be used. The upper range of molecular weights is less than 150 kilodaltons or less than 500,000 daltons, but these limits will be affected based on the linear and/or crosslinking properties of the PAA and whether the PAA is provided as a homopolymer or copolymer. Generally, molecular weight can be used as an indicator of the degree of neutralization of a given grade of PAA, with higher molecular weights often being somewhat acidic (i.e., not neutralized). It is noteworthy that the addition of certain PAA modifiers (especially when the additive is a weak acid such as citric acid) can be used as a practical means to adjust the neutralization status of PAA. At least partially neutralized and at least partially crosslinked PAA has proven particularly useful, but non-neutralized, fully neutralized, non-crosslinked, and fully crosslinked repeat PAA can also be used.

Examples

The chemicals used were: lightly neutralized, lightly crosslinked poly (acrylic acid) (with sodium), sodium silicate, sodium dihydrogen phosphate, linear poly (acrylic acid) (450KDa), calcium silicate, trisodium citrate dihydrate, citric acid, sodium hydroxide, calcium chloride, polyvinyl alcohol, and melamine were all obtained from Sigma Aldrich (Sigma Aldrich) and used without further purification. Tetraethylenepentamine and BPA-based epoxy resins were obtained from spain corporation (Hexion Inc) and did not require further purification. Carbopol 971P NF and Noveon AA-1 polycarbophil USP were obtained from Lubrizol Corporation (Lubrizol Corporation). Boric acid (particle size <500 μm) is available from the company Quiborax.

Preparation and characterization of mineralized PAA

Mineralization of PAA using NaOH: PAA was mineralized by dissolving 80 grams of unmodified PAA in 4 liters of 0.5m naoh until completely dissolved. PAA was then extracted by precipitation in cold methanol. A ratio of about 3:1 (methanol: water) was used to ensure complete extraction. After decanting the methanol solution, the solid was dried at 80 ℃ and again after grinding to a powder to ensure the sample was dry (confirmed via TGA). The resulting polymer was a white solid.

Calcium mineralization of unmodified PAA was carried out by dissolving 80 grams of unmodified PAA in 4 liters of 5M CaCl₂Until completely dissolved. PAA was then extracted by precipitation in cold methanol. A ratio of about 3:1 (methanol: water) was used to ensure complete extraction. After decanting the methanol solution, the solid was dried at 80 ℃ and dried again to complete dryness after grinding to a powder (confirmed via TGA). The resulting polymer was a white solid.

Analytical methods-thermal characterization of PAA and modified derivatives

Various experiments were conducted to confirm the feasibility of at least some of the inventive aspects contemplated herein.

Thermogravimetric analysis (TGA) was performed. 8-10mg of sample is used to heat the sample from 20 ℃ to 600 ℃ under air or nitrogen at a rate of 5 ℃/min or 10 ℃/min. This was done on TA Instruments brand Q500 TGA. Software processing in Universal Analysis^TMAnd (4) carrying out the process.

The propane lance test was designed to replicate a high velocity, high temperature flame using a conventional propane torch. Approximately 15mg of the sample was deposited into a platinum TGA pan and held 8-10 inches from the lance flame cone. The preliminary expansion capacity was assessed qualitatively by observation. (see FIG. 16, photographs before and after propane lance testing).

Measurement of PAA/mineral blends in epoxy systems Using the laboratory Meker burner testThe degree of swelling is good as shown in FIG. 17. Bunsen lamps produce a laminar flame, which rarely occurs in real flames. The grid in front of the Meker burner ensures turbulent flame, simulating the flame more realistically. In addition, 3X 0.5cm of coating was used³The cured "pucks" replace steel plates that were completely coated on the pucks as they were cured. Although an idealized test, the use of a "puck" allows for a better assessment of the paint's ability to expand due to the increased surface area exposed to the flame. These samples were burned for 5 minutes (with the burner set at 5cm from the coating surface) to observe the extent of swelling. The results were qualitatively determined by the degree of swelling relative to the initial and final coating thickness and the coke quality/hardness.

All powder samples were subjected to micro-scale combustion calorimetry (MCC) heating to 600 ℃ at a heating rate of 1 ℃/minute. Sample sizes were in the range of 5-10 mg. The test was performed on a Fire Testing Technology brand micro-scale combustion calorimeter. Data processing is performed via Origin brand software.

The conical heater test utilizes equipment conforming to ASTM standard E2102. The instrument utilizes a radiant conical heater located above a variable height sample stage and simultaneously used to balance the mass. When the sample is expanded, the laser line is broken and the stage height is then adjusted. Type 6K thermocouples protrude different distances through the plate and coating attached to Medtherm brand heat flux transducers. The sample was tested at 50kW/m2 for one hour. Preliminary exemplary data is shown below.

Fig. 18 depicts conditions for cone heater results for an exemplary boric acid-free experimental formulation comprising PAA and shows photographs of these results.

The adiabatic test is a preliminary test to determine whether a conical heater test is to be performed. The insulation test is used to measure the change in heat over time through the coating and into the underlying steel panel. A typical experiment was carried out at 15X 10X 0.3cm with a 5mm formulation coating³On a steel plate. The plate was placed vertically 5cm from the horizontally facing Meker spray gun. The UV thermometer was placed 12 inches away and temperature measurements were taken on the back of the plate every 30 seconds.

Cone Calorimetry (CC) was performed on all epoxy formulations coated on a 10 x 0.5cm3 fully coated steel panel on which the intumescent coating cured. The sample was run for 5 minutes using an incident heat flux of 50kW/m 2. The test was performed on a Fire Testing Technology brand cone calorimeter. Data processing was performed via MatLab software. Each formulation was tested three times to ensure statistically significant results.

Epoxy formulations and fire tests

Preparation of Meker. The initial base epoxy formulation was designed to have either 11 wt% or 22 wt% PAA additive with the remaining wt% portion being resin. In a given sample, 12.3g of epoxy resin was weighed into a 100mL Teflon dish. The additives (2.5 g for PAA based samples, 5.5g for mineralized PAA) were added to the epoxy resin and mixed for 5-10 minutes to ensure a completely homogeneous paste/viscous liquid. The consistency of the epoxy/additive is not uniform from sample to sample, providing a variety of viscosities.

After 5 minutes, 7.3g of the amine curing agent was stirred into a Teflon dish and stirred for 5-10 minutes. 3X 0.5cm was used regardless of the viscosity of the preparation³The mold of (2) casting the epoxy resin onto the steel plate. The samples were placed in a vacuum desiccator for one hour and then in an oven at 60 ℃ for 4 hours. All samples were allowed to cool to room temperature and then subjected to meker combustion.

Subsequently, a boric acid free intumescent formulation (see above) was used as an exemplary coating. In a given sample, the formulated non-boric acid intumescent epoxy resin (part a) was weighed into a 100mL teflon pan. The PAA additive was then added and mixed for 5-10 minutes to ensure a completely homogeneous paste/viscous liquid.

After 5 minutes, the formulated non-boric acid intumescent amine curing agent (part B) was stirred into a teflon pan and stirred for 5-10 minutes. Using 3X 0.5cm, regardless of the viscosity of the formulation³The mixture was cast on a steel plate (a-12 construction steel). The samples were then placed in a vacuum desiccator for one hour and then in an oven at 60 ℃ for 4 hours. After cooling, the samples were removed from the mold and sanded to ensure uniform thickness.

Working examples

Table 4 shows how each of these coatings was formulated, with further reference to the above abbreviations and procedures.

Table 4: intumescent coating formulations based on the same resin and different components。

Examples	1	2	3	4	5	6
							Part A						Commercial intumescent material
Titanium dioxide	2	2	2	2	2
							Ammonium polyphosphate	10	10	10	10	10
Other inorganic fillers	9.5	9.5	9.5	9.5	9.5
							Thixotropic wax	0.5	0.5	0.5	0.5	0.5
Diluent	11	11	11	11	11
							Epoxy resin	32	32	32	32	32
						65
							Part B
Other inorganic fillers	3.8	3.8	3.8	3.8	3.8
							Melamine (foaming agent)	7	7	7	7	7
Thixotropic wax	1.5	1.5	1.5	1.5	1.5
							Polyaminoamides	22	22	22	22	22
Reactive amine catalysts	0.7	0.7	0.7	0.7	0.7
							Total of 100.01						35.01
Unmodified PAA			14	27.5	11
							PAA-Na	13.75	27.5	14
SM	3.5
							CA	3.5
PVOH					16.5
Total weight of	120.76	127.51	128.01	127.51	127.51
							Expansion ratio	4.1	2.2	2.9	9.4	4.7	6
Crude coke toughness scale	5//5	5//5	5//5	3.75//5	5//5	5//5

Fig. 20A-20E show the coke structure produced by performing the Meker test on formulations 1, 2, 3, 4 and 5 in table 4, while fig. 20F shows the coke structure obtained in a commercially available boron-containing acid formulation.

Other promising formulations that need further investigation are samples comprising poly (vinyl alcohol) (PVOH). The polyphenolic substance PVOH has a plurality of hydroxyl moieties that readily form ethers. In addition, as degradation occurs, unsaturated regions occur along the backbone, creating a common precursor to coke. In recent years, the incorporation of PVOH into epoxy formulations has been reported in the literature and should be the object of further investigation of epoxy formulations.

Adiabatic testing (fig. 16) of commercial intumescent materials comprising boric acid versus experimental formulations comprising PAA (examples 4 and 1) showed that the performance of the experimental formulations was close to that of commercial products comprising boric acid.

In fig. 21, line a shows a bisphenol a epoxy coating (i.e., a control coating without an intumescent ingredient), and line B is an experimental formulation without boric acid and without PAA. Line C is a boric acid free experimental formulation comprising PAA, and line D is a boric acid free experimental formulation comprising PAA (example 1), and line E is a commercially available boric acid containing intumescent coating. The graph shows that PAA modified with inorganic compounds shows very good thermal insulation properties in terms of temperature and time compared to commercial products.

In various aspects of the present invention, the intumescent coating composition and (in some cases) the liquid intumescent coating composition may include any combination of the following features:

a coating binder system;

expanded packaging with poly (acrylic acid) and PAA modifier;

wherein the coating binder system comprises between 25.0 wt% to 75.0 wt% of at least one thermosetting polymer and at least one curing agent therefor;

wherein the PAA modifier comprises at least one of: poly (vinyl alcohol), poly (vinyl acetate), and combinations thereof;

wherein the PAA modifier is an inorganic mineral;

wherein the PAA modifier comprises at least one metal selected from Al, B, Zr, Cu, Zn, Na, K, Mg, Ca, Sr, Si and Ti;

wherein the metal is associated, bound or complexed with at least one selected from the group consisting of a hydrate, hydroxide, oxide, carbonate, bicarbonate, silicate, sulfate, nitrate, chloride and phosphate;

wherein the PAA modifier comprises a weak organic acid;

wherein the weak organic acids comprise citric acid, tartaric acid, ascorbic acid, lactic acid, formic acid, acetic acid, oxalic acid, uric acid, malic acid and/or itaconic acid;

wherein the poly (acrylic acid) is at least partially neutralized;

wherein the poly (acrylic acid) is at least partially crosslinked;

wherein the poly (acrylic acid) comprises at least 5.0 wt.% of the coating composition;

wherein the poly (acrylic acid) comprises no more than 50 weight percent of the coating composition;

wherein the poly (acrylic acid) has a molecular weight of at least 1,000 daltons;

wherein the poly (acrylic acid) has a molecular weight of at least 2,000 daltons;

wherein the poly (acrylic acid) has a molecular weight of no more than 1,500,000 daltons;

wherein the poly (acrylic acid) has a molecular weight of no more than 500,000 daltons;

wherein the coating binder is thermosetting or thermoplastic;

wherein the thermosetting adhesive system utilizes a single cure mechanism, a dual cure mechanism, a peroxide cure mechanism, a redox cure mechanism, or a UV cure mechanism;

wherein the thermosetting adhesive comprises an epoxy resin;

wherein the thermosetting adhesive comprises an epoxy resin and an amide;

wherein the dual cure mechanism includes an epoxy amide reaction and a Michael addition reaction; and

wherein the thermoplastic adhesive system is based on vinyl, styrene, acrylic or acrylate chemistries.

When coupled with inorganic compounds and integrated into epoxy or other coatings, the PAA blend was found to produce an expanded and tough coke with a thermal barrier efficiency comparable to commercially available expanded coatings. Thus, these PAA-based materials should have particular utility in a wide range of intumescent compositions and coating systems.

Generally, the chemical components and related ingredient items should also be selected for processability, cost, and weight. Unless otherwise indicated, all tests and measurements were performed under ambient conditions and relied on commercially available instruments according to the manufacturer's recommended operating procedures and conditions. Unless stated to the contrary (explicitly or in the context of a given disclosure), all measurements are in grams and all percentages are based on weight percent.

Although embodiments of the present invention have been illustrated in the accompanying drawings and described in the foregoing detailed description, it should be understood that the invention is not limited to the embodiments disclosed, but is also capable of numerous rearrangements, modifications and substitutions. The exemplary embodiments have been described with reference to preferred embodiments, but further variations and modifications cover the foregoing specific embodiments. Such variations and modifications are also intended to fall within the scope of the appended claims or equivalents thereof.