Fire resistant fiber reinforced polymer articles

Abstract

Articles composed of a fiber reinforced polymer (FRP) such as FRP utility poles and cross arms can include a fire resistant layer on or near at least one surface thereof. The fire resistant layer includes a geopolymer, which can be prepared from an aqueous formulation including geopolymer forming components of: (1) one or more metal silicates, (2) one or more metal oxide / hydroxides, (3) one or more water soluble caustic agents; and (4) water. In some implementations, the aqueous formulation can be free of, or substantially free of, solid particles, such as large solid particles, comprised of the metal silicate, metal oxide / hydroxide and water-soluble caustic agent.

Description

FIRE RESISTANT FIBER REINFORCED POLYMERARTICLES CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and all benefit of U.S. Provisional Application No. 63 / 740,287, filed December 30, 2024, the entire disclosure of which is fully incorporated herein by reference.TECHNICAL FIELD

[0002] The present disclosure is directed to articles including a fire resistant layer composed of a geopolymer, which can be prepared from geopolymer forming components that are more or less dissolved in an aqueous formulation.BACKGROUND

[0003] Fiber-reinforced polymers (FRPs) are a composite material made of a polymer matrix reinforced with fibers. The polymeric matrix can be thermosetting and / or thermoplastic resins. FRPs are commonly used in the aerospace, automotive, marine, and construction industries. Articles prepared from FRP are rapidly being adopted, in part, to replace wooden structures.

[0004] For example, electrical power lines are supported by a pole system, which includes a pole body, cross-arms, and insulators. Traditionally, poles are made from wood, steel, ductile iron, reinforced concrete, etc. and cross-arms are made from wood. FRP poles and FRP cross-arms are stronger, lighter, and longer-lasting than their wood counterparts.

[0005] However, traditional FRP poles are composed of glass fiber and a thermoset resin matrix, which can ignite and, in some cases, collapse in a forest fire. Some manufacturers use a fire resistant shield to cover lower portions of utility poles to protect the poles from a fire event. Others use an intumescent mesh wrapped on or affixed to the pole to provide protection against fire. However, the cost of current fire-resistant materials and difficulty in its application have limited their use. In addition, such shields do not protect the upper portions of a utility pole such as the cross arms.

[0006] Accordingly, a continuing need exists for an effective, economical, and operationally viable process to improve fire resistance, and in some cases UV resistance, of articles constructed from fiber-reinforced polymers.SUMMARY OF THE DISCLOSURE

[0007] Advantages of the present disclosure include fire resistant articles composed of a fiber reinforced polymer (FRP). Advantageously, the articles of the present disclosure include a fireresistant layer on or near at least one surface thereof. The fire-resistant layer of the present disclosure is composed of geopolymer which can be formed from an aqueous formulation including geopolymer forming components of: (1) a metal silicate; (2) a metal oxide / hydroxide; (3) a water-soluble caustic agent; and (4) water. Fire resistant layers prepared from the aqueous formulations of the present disclosure can also advantageously improve weather-resistance and / or ultraviolet light resistance of the underlying article and are environmentally benign.

[0008] In some implementations, the fire resistant layer can be formed as a geopolymer coating directly on at least one exterior surface of the article, and even on all exterior surfaces of the article. The geopolymer coating can be formed by applying the aqueous formulation on an exterior surface, or all exterior surfaces, of the article and curing the aqueous formulation to form the fire resistant layer.

[0009] In other implementations, the fire resistant layer can be formed by applying a geopolymer sheet adhered or fastened to the article. The geopolymer sheet can also be included on or near a surface of an FRP article during fabrication of the FRP. Advantageously, the geopolymer sheet can be prepared similar to forming a direct coating on a FRP article. That is, the geopolymer sheet can be prepared by applying the aqueous formulation on a sheet and curing, or partial curing, the aqueous formulation to form the geopolymer sheet. In some aspects, curing or partial curing can occur prior to, during, or after the geopolymer sheet is adhered or fastened to the FRP article, or during fabrication of the FRP article, to form the fire resistant layer on or near the surface of the FRP article.

[0010] An advantage of the aqueous formulation of the present disclosure is that it generally can have a low non-dissolved (or undissolved) solids content of the geopolymer forming components, and / or it generally can be free of, or substantially free of large solid particles of the geopolymer forming components. For example, the aqueous formulation can have a solids content of less than 10 wt% of the geopolymer forming components (metal silicate, metal oxide / hydroxide and water-soluble caustic agent) when the aqueous formulation is at a temperature of 25 °C. In addition, or as an alternative, the aqueous formulation can exclude solid particles of the geopolymer forming components (metal silicate, metal oxide / hydroxide and water-soluble caustic agent) that have an average diameter of greater than 5 pm when the aqueous formulation is at a temperature of 25 °C. Limiting the amount of solids in the aqueous formulation and limiting the size of solid particles in the aqueous formulation allows the formulation to be applied as one or more thin layers and / or applied by a liquid atomizer or liquid aerosol spray. Further, the aqueous formulation of the present disclosure advantageously can have all of the components that react to form a geopolymer (e.g., metal silicate, metal oxide / hydroxide, water-soluble caustic agent, andother reactive components) dissolved or substantially dissolved in the aqueous formulation, which facilitates preparation of thin layers of geopolymer from such a formulation.

[0011] In some aspects, the aqueous formulation can be formed by combining: (1) a metal silicate; (2) a metal oxide / hydroxide; (3) a water soluble caustic agent; and (4) water. It is understood that a metal hydroxide (e.g., a hydrated form of the metal oxide) can be used in place of a metal oxide in the present disclosure. The geopolymer forming components can be combined with sufficient water soluble caustic agent to dissolve or substantially dissolve the metal silicate and metal oxide / hydroxide in the formulation.

[0012] In some implementations, a FRP article having a fire resistant layer on an exterior surface thereof can be prepared by applying an aqueous formulation of the present disclosure directly on the FRP article; and curing the aqueous formulation into a geopolymer coating as the fire resistant layer on the article. Alternatively, or in addition to forming a direct fire resistant layer comprising a geopolymer directly on the surface of the FRP article, a fire resistant layer on an article can be formed by applying a geopolymer sheet to the FRP article. The geopolymer sheet can be formed by applying an aqueous formulation of the present disclosure onto a sheet; and curing the aqueous formulation to form the geopolymer sheet. The geopolymer sheet can be applied to the FRP article in a number of ways.

[0013] For example, in some implementations, the geopolymer sheet can be adhered or fastened to an FRP article to form the fire-resistant layer thereon. In addition, or as an alternative, an FRP article having a fire resistant layer on an exterior surface thereof can be prepared by incorporating a geopolymer sheet in the manufacturing process of such article. That is, a geopolymer sheet can be co-pultruded during production of an FRP article to form a fiber reinforced polymer having a fire resistant layer on or near at least one surface of the formed article. The article, which now has a fire resistant exterior layer, can further include an additional exterior fire-resistant layer or geopolymer sheet described in the previous paragraphs.

[0014] Aqueous formulations of the present disclosure can be readily applied by spraying, rolling, dipping, brushing, etc. the formulation on an exterior surface of a FRP article or sheet to form a geopolymer coating thereon. In addition, more than one aqueous formulation of the present disclosure can be applied to the same exterior surface of the FRP article or sheet to form a multilayered coating on the exterior surface of the FRP article or on the sheet. In some implementations, the applied aqueous formulations of the present disclosure can be cured in air or in an inert atmosphere, e.g., nitrogen, and at a temperature of from about 5 °C to about 150 °C, such as about 25 °C to about 100 °C.

[0015] Implementations of the present disclosure include one or more of the following features individually or combined. For example, the aqueous formulation of the present disclosure can further comprise optional components such as: (5) one or more catalysts or activators; (6) one or more pigments; (7) one or more rheology modifiers; (8) one or more ceramic particles; (9) one or more fibers; (10) one or more surfactants; or any combination thereof. Certain of these optional components may or may not be soluble in the aqueous formulation and may be solid components of the aqueous formulation.

[0016] In some implementations, the metal silicate comprises one or more of: alkali metal silicate, alkaline earth metal silicates, sodium silicate, sodium silicate, lithium silicate, potassium silicate, neosilicates, sorosilicates, cyclosilicates, inosilicates, phyllosilicates, tectosilcates, Mullite, Kaolinite, Muscovite, or any combination thereof. In other implementations, the metal oxide / hydroxide comprises one or more of: a group 2-15 metal oxide / hydroxide such as aluminum trihydrate (ATH) (also known as aluminum hydroxide (A1(OH)3), zinc oxide (ZnO), iron oxide, titanium dioxide (TiCh), copper oxide, tin oxide, zirconium oxide, manganese oxide, nickel oxide, silver oxide, vanadium oxide, bismuth oxide, or any combination thereof. Further, the metal oxide / hydroxide can be used as the hydrated (hydroxy) form of itself. In still further implementations, the water soluble caustic agent comprises one or more of: an alkali metal hydroxide, Na2O(SiC>2), Li2O(SiC>2), K2O(SiC>2), ammonium hydroxide, or a combination thereof.

[0017] In other implementations, FRP articles having a fire-resistant layer on an exterior surface can include utility poles, cross arms, railroad ties, etc.

[0018] Further, in some aspects, the fire resistant layer can have a thickness of less than about 5 mm, such as less than 2 mm. For example, the fire-resistant layer including a geopolymer can have a thickness in the range of 1 mil to 50 mils (25 pm to 1,270 pm).

[0019] Additional advantages of the present disclosure will become readily apparent to those skilled in this art from the following detailed description, wherein only certain embodiments are shown and described, simply by way of illustration of carrying out certain subject matter. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various respects, all without departing from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Reference is made to the attached drawings, wherein elements having the same reference numeral designations represent similar elements throughout and wherein:

[0021] FIG. 1A illustrates a FRP utility pole with cross arms having a fire-resistant layer directly on the pole and cross arms as a coating on exterior surfaces thereof according to an implementation of the present disclosure.

[0022] FIGS. IB and 1C illustrate cross-sectional views of the utility pole and a cross arm of FIG. 1A, each of which include a fire-resistant layer directly coated thereon according to an implementation of the present disclosure.

[0023] FIG. 2 illustrates a fire-resistant layer on an FRP utility pole formed by applying a geopolymer sheet around the exterior surface of the utility pole.

[0024] FIGS. 3A, 3B and 3C illustrate a chamber and sections of a FRP utility pole subjected to flame test. In particular, FIG. 3 A illustrates a burn chamber composed of a steel barrel and four propane torches inserted at the base of the barrel and directed to one another. FIG. 3B illustrates an FRP pole section without a fire resistant layer after being exposed to flames of the four propane torches in the burn chamber and FIG. 3C illustrates an FRP pole section having a fire resistant layer according to an implementation of the present disclosure after being exposed to flames of the four propane torches in the burn chamber.DETAILED DESCRIPTION OF THE DISCLOSURE

[0025] The disclosure may be more fully appreciated by reference to the following description, including the following definitions and examples. Certain features of the disclosed compositions and methods which are described herein in the context of separate aspects, may also be provided in combination in a single aspect. Alternatively, various features of the disclosed compositions and methods that are, for brevity, described in the context of a single aspect, may also be provided separately or in any sub-combination.

[0026] Unless otherwise defined herein, scientific and technical terms used in connection with the present application shall have the meanings that are commonly understood by those of ordinary skill in the art. Further, unless otherwise required by context, singular terms shall include pluralities and plural terms shall include the singular.

[0027] As employed above and throughout the disclosure, the following terms and abbreviations, unless otherwise indicated, shall be understood to have the following meanings.

[0028] As used in the specification including the appended claims, the singular forms “a,” “an,” and “the” include the plural, and reference to a particular numerical value includes at least that particular value, unless the context clearly dictates otherwise.

[0029] As used in the specification including the appended claims, when a range of values is expressed, such range includes from the one particular value and / or to the other particular value.All ranges are inclusive and combinable. Further, reference to values stated in ranges includes each and every value within that range. The term “about” as used herein when referring to a measurable value such as an amount, a temporal duration, and the like, is meant to encompass reasonable variations of the value.

[0030] The present disclosure is directed to one or more fire-resistant layers on or near a surface of an article composed of a fiber-reinforced polymer (FRP). FRP can include fibers in a polymer matrix, e.g., a thermoset matrix or thermoplastic matrix. A variety of fibers can be used as the FRP and include, without limitation glass, carbon, nylon, aramid, basalt, etc. or any combination thereof. Also, a variety of thermosets can be used for the FRP, which include, without limitation, polyurethanes, polyesters, vinylesters, epoxy resins, acrylics, etc. or any combination thereof. Further, thermoplastic matrices that can be used for the FRP, include without limitation, polypropylene, polyvinylchloride, polyethylene terephthalate, nylon, polyphenylene sulfide, etc. or any combination thereof.

[0031] FRP can be fabricated into a variety of articles such as construction articles, e.g., a utility pole, cross arm, railroad tie, etc., component articles such as for aerospace, automotive, marine articles, etc. The FRP article is not limited to a particular shape, and can include structural and non-structural polymer components used in aerospace, automotive, marine, and construction, etc. The FRP article can be in the form of any structural shapes, including, but not limited to, C-channels, I-beams, wideflange H-beams, square and round tubes, angles, sandwich panels, etc. FRP articles can be manufactured from an FRP by pultrusion, pull-winding, filament winding, resin infusion, roll-wrapping, pre-preg, or combinations thereof. Such articles advantageously can benefit from a fire resistant layer of the present disclosure since they are typically in locations that can be susceptible to a fire event and susceptible to UV radiation.

[0032] In some implementations, the fire resistant layer can be formed as a coating directly on at least one exterior surface of the article, and even on all exterior surfaces. In other implementations, the fire resistant layer can be formed by a geopolymer sheet adhered or fastened to the article. Advantageously, the geopolymer sheet can be prepared similarly to forming a direct coating on the article. In other aspects, an FRP article can have a fire resistant layer with a thickness of no more than about 5 mm, e.g., no more than about 2 mm. For example, the fire resistant layer can have a thickness in the range of 1 mil to 50 mils (25 pm to 1,270 pm) such as from 2-20 mils (51 pm to 508 pm), 2- 10 mils (51 pm to 254 pm), 2.5 mils - 6 mils, 3- 4 mils, for example.

[0033] FIGS. 1 and 2 illustrate example articles, e.g., a utility pole, having a fire resistant layer according to various aspects of the present disclosure.

[0034] As shown in the views of FIGS. 1A-1C, a utility pole (100) can include a pole (102) with cross arms (104). For this example, utility pole 100 includes power lines (106), but other or alternative equipment can be included on the utility pole including communication cables, lights, transformers, antenna, etc. Each of the pole and cross arms independently can be composed of a fiber reinforced polymer. FIG. IB illustrates a cross-sectional view of the pole (102) composed of an FRP (110) having a fire resistant layer directly thereon as a geopolymer coating on the exterior circumferential surface (120). As illustrated in the example of FIG. IB, the pole can have a hollow interior (130) formed by the FRP (110). FIG. 1C illustrates a cross-sectional view of one cross arm (104), which is composed of an FRP (112) having a fire resistant layer directly thereon as a geopolymer coating on the exterior surface (122). As illustrated in the example of FIG. 1C, the cross arm can have a hollow interior (132) formed by the FRP (112). The utility pole and cross arms can be composed of an FRP including glass fibers in a matrix composed of a polyurethane, unsaturated polyester, acrylic, vinylester, epoxy, or a combination of two or more thereof, for example. FRP utility poles and crossarms can be manufactured from an FRP by pultrusion, pullwinding, filament winding, resin infusion, roll-wrapping, pre-preg, or combinations thereof. Advantageously, the fire-resistant layer as a geopolymer coating directly on a pole or cross arm can improve the fire resistance of such structures as well as improve weather-resistance, scratch resistance, and ultraviolet light resistance of the underlying article and is environmentally benign.

[0035] As an alternative or in addition, FIG. 2 illustrates applying a geopolymer sheet to an FRP article to form the fire-resistant layer on an exterior surface of the article. In particular, FIG.2 shows applying a geopolymer sheet (230) on an FRP utility pole (202). The geopolymer sheet can be prepared by applying an aqueous formulation of the present disclosure on a sheet (e.g., a porous or a non-porous sheet) and curing the formulation by drying to form the geopolymer sheet. In some aspects, curing or partial curing the applied aqueous formulation can occur prior to, during, or after the geopolymer sheet is adhered or fastened to the FRP article to form the fire resistant layer on the FRP article.Aqueous Formulations

[0036] Advantageously, aqueous formulations of the present disclosure can be composed of relatively low cost components and can be readily applied to a surface of an FRP article or to one or two major surfaces of a porous or non-porous sheet to be applied to the FRP article. A geopolymer forms from the aqueous formulation and can bond to the surface as it dries to form a fire resistant (FR) layer. Fire resistant layers prepared from the formulations of the present disclosure can also advantageously improve weather-resistance and / or ultraviolet light resistance of the underlying article and are environmentally benign.

[0037] In certain aspects, an aqueous formulation of the present disclosure can include geopolymer forming components of: (1) a metal silicate; (2) a metal oxide / hydroxide; (3) a water-soluble caustic agent; and (4) water. The metal silicate, metal oxide / hydroxide, water-soluble caustic agent components of the aqueous formulation can react to form a geopolymer when the formulation is dried. As discussed further below, the geopolymer forming components of the formulation advantageously can be dissolved or substantially dissolved in the formulation. Moreover, the aqueous formulation can include components other than the geopolymer forming components, which may or may not be dissolved or substantially dissolved in the formulation.

[0038] An advantage of the aqueous formulation of the present disclosure is that it generally can have a low solids content, and / or it generally can be free of, or substantially free of large solid particles. For example, the aqueous formulation can have a low solids content comprised of the metal silicate, metal oxide / hydroxide and water-soluble caustic agent. In addition, or as an alternative, the aqueous formulation can be free of, or substantially free of, large solid particles comprised of the metal silicate, metal oxide / hydroxide and water-soluble caustic agent. Limiting the solids content and / or size of solid particles in the aqueous formulation allows the formulation to be applied as one or more thin layers, and / or applied by liquid atomizer or liquid aerosol spray. Further, the aqueous formulation of the present disclosure advantageously can have all of the components that react to form a geopolymer (e.g., metal silicate, metal oxide / hydroxide, water-soluble caustic agent, and other reactive components) dissolved or substantially dissolved in the aqueous formulation to allow deposition of thin coating layers from such a formulation. In an aspect, the fire resistant layer can have a thickness of less than about 5 mm, such as less than 2 mm. For example, the fire-resistant layer including a geopolymer can have a thickness in the range of 1 mil to 50 mils (25 pm to 1,270 pm).

[0039] In addition, the aqueous formulation can include components other than the geopolymer forming components which may or may not be dissolved or substantially dissolved in the composition. However, it can be advantageous to limit the solids content and / or particle size of such other components so that when they are included, the aqueous formulation still has a low solids and / or low particle size when the aqueous formulation is at a temperature of 25 °C.

[0040] In certain aspects, the aqueous formulation of the present disclosure has a solids content, including all components of the formulation, of no more than 10 weight percent (wt%) based on the total weight of the formulation and when the formulation is at a temperature of 25 °C. For example, the aqueous formulation of the present disclosure can include no more than 8 wt%, 6 wt% 4 wt%, 2 wt%, 1 wt%, and even less than 1 wt%, of solids of all components of the aqueous formulation, based on the total weight of the composition at a temperature of 25 °C.

[0041] In other aspects, the aqueous formulation is free of, or substantially free of, solid particles comprised of the metal silicate, metal oxide / hydroxide and water-soluble caustic agent having no more than 10 wt% of such solid particles based on the total weight of the formulation at a temperature of 25 °C. In other implementations, the aqueous formulation has a solids content of no more than 8 wt%, 6 wt% 4 wt%, 2 wt%, or 1 wt% of the geopolymer forming components (the metal silicate, metal oxide / hydroxide and water-soluble caustic agent) when the aqueous formulation is at a temperature of 25 °C.

[0042] In another aspect of the present disclosure, the aqueous formulation can exclude geopolymer forming solid particles (e.g., the metal silicate, metal oxide / hydroxide and water-soluble caustic agent), or any type of solid particles, having an average diameter of greater than 10 pm, e.g., having an average diameter of no more than 5 pm, 3 pm, 2 pm, or no greater than 1 pm, when the aqueous formulation is at a temperature of 25 °C. In some implementations, the aqueous formulation of the present disclosure can be a solution of its components at a temperature of 25 °C with no detectible solid particles as determined by filtering the solution through a 0.5 pm filter at a temperature of 25 °C or by an equivalent determination.

[0043] In other implementations, the aqueous formulation of the present disclosure can include optional components such as: (5) one or more catalysts or activators, e.g., carbonates or bicarbonates, phosphate acids and partial acids, or organic carboxylic acids to modify time of cure and / or reactivity of the formulation components; (6) one or more pigments, e.g., to adjust color; (7) one or more rheology modifiers; (8) one or more ceramic particles such as ceramic spheres, Zeeospheres, Carborundum (SiC), AI2O3, etc.; (9) one or more fibers such as those composed of cellulose or cellulose derivatives, jute, coir, a polyamide, polyethylene terephthalate, acrylic, modacrylic, polyacrylonitrile, polyvinylalcohol, basalt, glass, quartz, carbon, etc.; (10) one or more surfactants; or any combination thereof. Certain of these components may or may not be soluble in the aqueous formulation and may be solid components of the formulation when the aqueous formulation is applied. However, in some implementations, the aqueous formulation which includes such optional components is free of, or substantially free of, solid particles comprised of such optional components.

[0044] The amounts of the components used to form the aqueous formulation can be adjusted for ease of application of the formulation to a substrate and the desired characteristics of the formed fire-resistant layer. For example, the aqueous formulation can have a weight ratio of the metal silicate to metal oxide / hydroxide ranging from about 5:1 to 1:5, e.g., from about 4.5:1, 4:1, 3.5:1, 3:1, 2.5:1, 2:1, 1.5:1, 1:1 to 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, and any value thereof or therebetween. For example, the aqueous formulation can have a weight ratio of the metal silicateto metal oxide / hydroxide ranging from about 1:1 to about 1:3 for rapid curing formulations and from about 3:1 to about 1.5:1 to form very thin coating layers. In some implementations the aqueous formulation includes, based on the total weight of the aqueous formulation, 10% to 45% of the (1) metal silicate; 5% to 65% of the (2) metal oxide / hydroxide; 5% to 30% of the (3) water soluble caustic agent. In addition, the aqueous formulation can include, based on the total weight of the aqueous formulation, 25% to 80% of the water. For example, when used for dip-coating, the aqueous formulation can be formed from, on a weight basis, 10% to 30% of the (1) metal silicate; 30% to 40% of the (2) metal oxide / hydroxide; 5% to 10% of the (3) water soluble caustic agent; and 20% to 50% of the (4) water, based on the total weight of the formulation. When used for an atomized spray application, the aqueous formulation can be formed from, on a weight basis, 15% to 35% of the (1) metal silicate; 5% to 30% of the (2) metal oxide / hydroxide; 10% to 25% of the (3) water soluble caustic agent; and 35% to 70% of the (4) water, based on a total weight of the formulation. Although, the metal silicate and the metal oxide / hydroxide components are listed separately in the present disclosure, these components can be included in the aqueous formulation from a source that has both of these components together, such a kaolin, etc. and forming the aqueous formulation is not limited to using the metal silicate and the metal oxide / hydroxide as separate components.

[0045] Useful metal silicates that can be used to form the aqueous formulations of the present disclosure include one or more of: alkali metal silicate, alkaline earth metal silicates, sodium silicate, sodium silicate, lithium silicate, potassium silicate, neosilicates, sorosilicates, cyclosilicates, inosilicates, phyllosilicates, tectosilcates, Mullite, Kaolinite, Muscovite, or any combination thereof. The alkali metal silicate can include a sodium silicate, e.g., sodium metasilicate, Na2.vSirO2r .1- or (Na2O). (SiO2)j, such as sodium metasilicate (Na2SiOs), sodium orthosilicate (Na4SiO4), sodium pyrosilicate (NaeSi?©?), etc. These sodium silicate compounds are generally colorless transparent solids or white powders, and soluble in water in various concentrations. In some aspects of the present disclosure, the formulations comprise sodium metasilicate as the majority of the metal silicate, e.g., the metal silicate comprises at least 50 wt% sodium metasilicate such as at least 60 wt% of sodium metasilicate of the metal silicate.

[0046] Metal oxides and metal hydroxides that can be used to form the aqueous formulations of the present disclosure include one or more group 2-15 metal oxides or hydroxides. For example, useful metal oxides and metal hydroxides include: aluminum trihydrate (ATH) (Al(0H)3), zinc oxide (ZnO), iron oxide, titanium dioxide (TiCh), copper oxide, tin oxide, zirconium oxide, manganese oxide, nickel oxide, silver oxide, vanadium oxide, bismuth oxide or any combination thereof. Further, it is understood that metal oxides in aqueous solutions convert to their equivalenthydroxide, and thus the use of metal hydroxide is equivalent to use of the metal oxide (e.g., ZnO is equivalent to Zn(0H)2). Hence, a metal oxide in the present disclosure is understood to include or be substituted for its metal hydroxide. In some aspects of the present disclosure, the formulations are formed from aluminum trihydrate as the metal oxide / hydroxide in percent of the metal oxide / hydroxide of at least 20 wt % of the total metal oxide / hydroxide, e.g., 20 wt% to 100 wt%; 10 wt% to 50 wt%; or 75 wt% to 100 wt% of the total metal oxide / hydroxide.

[0047] The water soluble caustic agent of the aqueous formulation is designed to facilitate dissolution of the alkali metal silicate and metal oxide / hydroxide in water and any other component that can react with the alkali metal silicate and metal oxide / hydroxide in water. Examples of water soluble caustic agents useful for the present disclosure include, without limitation, one or more of: an alkali metal hydroxide (such as NaOH, KOH), alkali metal carbonates (such as Na2COs, K2CO3), alkali metal phosphates (such as NasPO4, K3PO4), Na2O(SiO2), ammonium hydroxide, or one or more combinations thereof. Sufficient amount of water soluble caustic agent is combined with the alkali metal silicate and metal oxide / hydroxide to form an aqueous formulation with the desired level of solids. In certain aspects, the amount of water soluble caustic agent is added to increase the pH of the aqueous formulation to generate a pH of no less than 8, such as a pH no less than 8.5, 9, 9.5, 10, 10.5, 11, 12, 12.5, 13, 13.5, 14, etc. Increasing the pH tends to increase the amount of alkali metal silicate and metal oxide / hydroxide dissolved in the aqueous formulation.

[0048] In some aspects, the aqueous formulations of the present disclosure has at least 95 wt% of the alkali silicate content as silicate ions in solution. This state can be determined, for example, when a solution of the alkali silicate can be passed through a 0.5 pm filter with no remaining visible particulate residue.

[0049] To facilitate spray application of the aqueous formulations of the present disclosure, the formulation can have a viscosity ranging from about 20 cP to about 2,000 cP as determined by cup and bob viscosity measurement at a temperature of 85 °F (29.4 °C). For example, the aqueous formulations of the present disclosure can have a viscosity ranging from about 20 cP to about 200 cP to form very thin, uniform fire-resistant layers, and viscosity of about 140 cP to about 700 cP for thicker, rougher layers. Viscosity of the system measured by rotational viscometry (cup and bob viscosity measurement) is performed as per ASTM D2196, D2556, D7867.

[0050] The aqueous formulations of the present disclosure can be prepared by combining: (1) a metal silicate; (2) a metal oxide / hydroxide; (3) a water soluble caustic agent; and (4) water to form the formulation. The (1) metal silicate and (2) the metal oxide / hydroxide can be from the same source material or separate source materials or a combination thereof. Preparing aqueous formulation can further include combining other components that can react with the metal silicateand the metal oxide / hydroxide dissolved in, or substantially dissolved in, the formulation and combining other optional components.

[0051] As explained earlier, in some implementations the prepared aqueous formulation can be free of, or substantially free of, solids comprised of the metal silicate, metal oxide / hydroxide and water-soluble caustic agent and even free of or substantially free of any other solid particles. Such aqueous formulations can be prepared by substantially or completely dissolving the reactive components in water, including mixing and / or heating the formulation until the desired dissolution of the components. In addition, or alternatively, preparing the aqueous formulation can include filtering the formed formulation to remove solid particles and / or decanting the formed formulation from solid particles. Filtering can be carried out by passing the formulation through a 0.5 pm to 50 pm filter or any range therebetween. In some aspects, preparing the aqueous solution can be carried out by shear mixing, agitation, planetary centrifugal mixing, in-line static mixing, or other processes of combining liquid and solid components for dissolution or substantial dissolution. Particulate remnants may also be separated gravitationally or by centrifugal separation.

[0052] In certain aspects, the aqueous formulation can include one or more optional components, e.g., a catalyst, activator, pigment, rheology modifier, ceramic particle, fibers, surfactant, or any combination thereof. For example, the aqueous formulation can include an optional pigment such as an organic pigment, e.g., carbon black, etc., and / or an inorganic pigment, e.g., ultramarine blue (a complex sulfur-containing sodium-silicate), iron oxide, titanium oxide, or copper oxide, etc. Certain of these components may or may not be soluble in the aqueous formulation and may form solid components in the aqueous formulation. However, in some implementations, the aqueous formulation is free of, or substantially free of, solid particles comprised of the metal silicate, metal oxide / hydroxide and water-soluble caustic agent. In one aspect, an optionally included pigment can be selected from an inorganic pigment (e.g., iron oxide, titanium oxide, or copper oxide) that can react with and covalently bond to the metal silicate and / or metal oxide / hydroxide upon forming a geopolymer from the aqueous formulation. In some aspects, such a reactive pigment can be dissolved or substantially dissolved in the formulation to facilitate reaction with other reactive components in the aqueous formulation.Forming Geopolymer Coatings

[0053] In certain implementations, a fire-resistant layer can be formed from the aqueous formulation by directly applying the aqueous formulation on at least one exterior surface of the FRP article and drying the applied formulation to cure the composition into a fire resistant layer as a geopolymer coating directly on the FRP article.

[0054] In other implementations, the fire-resistant layer can be formed by applying an aqueous formulation of the present disclosure onto one or both major surfaces of a sheet to form a geopolymer sheet and applying the geopolymer sheet to at least one exterior surface of the FRP article. Advantageously, the geopolymer sheet can be prepared similar to forming a direct geopolymer coating on the FRP article. That is, the geopolymer sheet can be prepared by applying an aqueous formulation of the present disclosure on a sheet (e.g., a porous or non-porous sheet) and curing the aqueous formulation on the sheet to form the geopolymer sheet. In some aspects, curing or partial curing can occur prior to, during, or after the geopolymer sheet is adhered or fastened to the article to form the fire resistant layer on the FRP article.

[0055] A sheet herein refers to a substantially flat article having width and length dimensions substantially greater than a transverse thickness dimension such as a width and length dimension at least one order of magnitude greater than the thickness dimension. In some aspects, the sheet is a porous sheet that can be impregnated by the aqueous formulation. Such porous sheets include, for example, a woven, non-woven, or knit fabric, felt, paper, veil, scrim, a cellulosic material, or any combinations thereof. In certain aspects, the cellulosic material can include corrugated paper board, fiber board, kraft paper, or any combination thereof. In some aspects, the porous sheet can include a plurality (more than one) of fibers. For example, the porous sheet can include fibers composed of cellulosics and cellulosic derivatives, polyamide, aramid, polyethylene terephthalate, polyvinyl alcohol, polyvinylbutyral, acrylic, glass, basalt, carbon, or any combination thereof. In other aspects, the sheet can be a non-porous sheet with a geopolymer on at least one major surface thereof formed from an aqueous formulation of the present disclosure. Such non-porous sheets include, for example, a metallic foil, plastic film, or otherwise thin material.

[0056] The geopolymer sheet can be prepared by applying the aqueous formulation onto a major surface, and / or on an opposing major surface of the sheet, and drying (e.g., in air) the applied formulation to at least partially cure the formulation to form the geopolymer sheet. The geopolymer sheet can be applied to an FRP article to form the fire resistant layer on or near a surface of the FRP article. The geopolymer sheet can be applied to an FRP article by adhering or fastening the geopolymer sheet to a surface of the FRP article. Alternatively, or in addition, the geopolymer sheet can be applied by incorporating it during manufacture of the FRP article such that the geopolymer sheet is on or near a surface of the FRP article thereby forming the fire-resistant layer.

[0057] As explained earlier the components of the aqueous formulation are prepared from geopolymer forming components of (1) a metal silicate; (2) a metal oxide / hydroxide; (3) a water-soluble caustic agent; and (4) water. In some implementations, the aqueous formulation can havea low solids content and / or can be free, or substantially free, of large solid particles such as solid particles of the metal silicate, metal oxide / hydroxide and water-soluble caustic agent. Limiting the solid particle content and / or size of solid particles in the aqueous formulation permits forming a fire resistant layer as one or more thin layers. A geopolymer is believed formed from the aqueous formulation by a reaction among the metal silicate, metal oxide / hydroxide and water-soluble caustic agent dissolved in the formulation to form the geopolymer. In certain aspects, the aqueous formulation of the present disclosure advantageously can have all of the components that react to form the geopolymer (e.g., metal silicate, metal oxide / hydroxide, water-soluble caustic agent, and other reactive components) dissolved or substantially dissolved in the formulation to allow formation of thin and uniform geopolymer coating layers from such a formulation. Moreover, such aqueous formulations can be applied to form a multi-layer coating with each layer prepared from the same or from a different aqueous formulation.

[0058] In some implementations, a fire-resistant layer can be formed by applying one or more aqueous formulations of the present disclosure onto the article. The aqueous formulation can be applied to a surface of the FRP article or sheet in a variety of ways including brushing, rolling, spraying, dip coating, etc. In one aspect, the aqueous formulation is applied directly to the FRP article, or on a sheet to be applied to the article, by spraying the aqueous formulation thereon as an aerosol, e.g., a suspension of fine liquid droplets in air or another gas. Aerosol sprays can be generated from aerosol spray dispensers, atomizers, etc.

[0059] In some implementations, one or more aqueous formulations can be applied to produce a fire-resistant layer as multilayered coating with each coating layer prepared from the same or from different aqueous formulations. For example, a first and second aqueous formulation can be applied to produce a first layer and a second layer of a multilayered coating. In such a way, the first layer can have a composition based on the first aqueous formulation and the second layer can have a composition based on the second aqueous formulation. The composition of the first and second layers can be the same or different. The first and second layers can be composed of different compositions by differing the type and / or amounts of the components that comprise the first and second aqueous formulations.

[0060] Concurrent with or after applying the one or more aqueous formulations to a surface of the FRP article or sheet, the formulation dries or is dried. Drying the aqueous formulation causes it to cure and form a geopolymer that can bond to the applied surface. Upon drying, the reactive components of the formulation form long-range, covalently bonded, non-crystalline (amorphous) networks resulting in a geopolymer.

[0061] Curing the aqueous formulation can be carried out conveniently in air, or in an inert gas, e.g., nitrogen, at ambient conditions. Curing can also be accelerated by heat and / or reduced pressure. For example, the aqueous formulation can be cured by drying in air, or in an inert gas, from a temperature range of about 5 °C to about 150 °C, e.g., from about 20 °C to about 100 °C.

[0062] In some implementations, an FRP article can have a fire resistant layer with a thickness of no more than about 5 mm, e.g., no more than about 2 mm, such as for example, 1 mil to 50 mils (25 pm to 1,270 pm). The fire resistant layer can be composed of geopolymer coating directly on the FRP article. Alternatively, or in addition, the fire resistant layer can comprise a geopolymer coated sheet. As ether a direct coating on the FRP article or as a coating on a sheet, the geopolymer coating can include more than one layer and each layer can have a thickness in the range of 1 mil to 50 mils (25 pm to 1,270 pm) such as from 2-20 mils (51 pm to 508 pm), 2- 10 mils (51 pm to 254 pm), 2.5 mils - 6 mils, 3- 4 mils, for example.EXAMPLES

[0063] The following examples are intended to further illustrate certain aspects of the subject technology and are not limiting in nature. Those skilled in the art will recognize, or be able to ascertain, using no more than routine experimentation, numerous equivalents to the specific substances and procedures described herein.

[0064] An aqueous formulation of the present disclosure was prepared from the components listed in Table 1 below.Table 1.

[0065] A fiber reinforced polymer pole was received from a commercial source and cut into several sections. The aqueous formulation prepared with the components listed in Table 1 was sprayed onto the exterior surface of one section the pole section and then dried to form a fire-resistant layer on the exterior surface of the pole section.

[0066] A bum chamber was configured from an open steel barrel by inserting four propane torches at the base of the barrel. The propane torches were configured as shown in FIG. 3A. Asection of the FRP pole was then placed in the chamber and the propane torches ignited. The pole sections were exposed to the flames for 3 minutes. The test was designed to evaluate the effectiveness of a fire resistant layer according to the present disclosure under conditions that may occur in a forest fire, which can have an extremely high temperature but only for a few minutes.

[0067] FIG. 3B is an illustration of an FRP pole section without a fire resistant layer after being exposed to flames of the four propane torches in the burn chamber. FIG. 3C is an illustration of the FRP pole section having a fire resistant layer prepared with the aqueous formulation as described above after being exposed to flames of the four propane torches in the bum chamber. As shown in FIG. 3B, the uncoated pole section was badly destroyed by the flame test. It was observed that flame and smoke from the pole section having the fire resistant layer were much less than from the uncoated pole section. There was some degradation on the pole section with the fire resistant layer up to a depth of about 0.12 inches (the wall of the pole section was 0.75 inches). The pole section with the fire resistant layer had many blisters but the fire resistant layer largely maintained its integrity after the flame test as shown in FIG. 3C. Only a few cracks were observed in the fire resistant layer at the site of a torch flame.

[0068] Only certain features and aspects of the present disclosure and examples of their versatility are shown and described in the present disclosure. It is to be understood that the technology disclosed herein is capable of use in various other combinations and environments and is capable of changes or modifications. Thus, for example, those skilled in the art will recognize, or be able to ascertain, using no more than routine experimentation, numerous equivalents to the specific substances, procedures and arrangements described herein. Such equivalents are considered to be within the scope of the invention and are covered by the following claims.

Claims

WHAT IS CLAIMED IS:

1. An article comprising:a fiber reinforced polymer having a fire resistant layer on or near at least one surface thereof, wherein the fire resistant layer comprises a geopolymer formed from an aqueous formulation including geopolymer forming components of: (1) a metal silicate; (2) a metal oxide; (3) a water-soluble caustic agent; and (4) water;wherein the aqueous formulation has a solids content of less than 10 wt% of the geopolymer forming components when the aqueous formulation is at a temperature of 25 °C, and / or the aqueous formulation excludes solid particles of the geopolymer forming components having an average diameter of greater than 5 pm when the aqueous formulation is at a temperature of 25 °C.

2. The article of claim 1, wherein the fire resistant layer includes a geopolymer sheet adhered or fastened to the article, wherein the geopolymer sheet is formed by curing the aqueous formulation on a porous or nonporous sheet.

3. The article of claim 1, wherein the aqueous formulation has a solids content of less than 10 wt% of the geopolymer forming components when the aqueous formulation is at a temperature of 25 °C.

4. The article of claim 1, wherein the aqueous formulation excludes solid particles of the geopolymer forming components having an average diameter of greater than 5 pm when the aqueous formulation is at a temperature of 25 °C.

5. The article of claim 1, wherein the fire resistant layer is a geopolymer coating directly on the at least one surface.

6. The article of claim 1, wherein the article is a utility pole, cross arm, or railroad tie.

7. The article of any one of the proceeding claims, wherein the aqueous formulation has a solids content of less than 5 wt% of the geopolymer forming components when the aqueous formulation is at a temperature of 25 °C, and / or the aqueous formulation excludes solid particles having an average diameter of greater than 3 pm of the geopolymer forming components when the aqueous formulation is at a temperature of 25 °C.

8. The article of any one of the proceeding claims, wherein the aqueous formulation is a solution of the geopolymer forming components at 25 °C.

9. The article of any one of the proceeding claims, wherein the ratio of metal silicate to metal oxide / hydroxide ranges from about 5:1 to 1:5.

10. The article of any one of the proceeding claims, wherein the metal silicate comprises at least 50 wt% sodium metasilicate based on a total weight of the metal silicate.

11. The article of any one of the proceeding claims, wherein the aqueous formulation includes, based on the total weight of the aqueous formulation, 10% to 45% of the (1) metal silicate; 5% to 65% of the (2) metal oxide / hydroxide; and 5% to 25% of the (3) water soluble caustic agent.

12. The article of any one of the preceding claims, wherein the aqueous formulation has a pH of no less than 9.

13. The article of any one of the preceding claims, wherein the metal silicate comprises one or more of: alkali metal silicate, alkaline earth metal silicates, sodium silicate, sodium silicate, lithium silicate, potassium silicate, neosilicates, sorosilicates, cyclosilicates, inosilicates, phyllosilicates, tectosilcates, Mullite, Kaolinite, Muscovite, or any combination thereof.

14. The article of any one of the preceding claims, wherein the metal oxide / hydroxide comprises one or more of: aluminum trihydrate, zinc oxide, iron oxide, titanium dioxide, copper oxide, tin oxide, zirconium oxide, manganese oxide, nickel oxide, silver oxide, vanadium oxide, bismuth oxide, or any combination thereof.

15. The article of any one of the preceding claims, wherein the water soluble caustic agent comprises one or more of: an alkali metal hydroxide, Na2O(SiC>2), or ammonium hydroxide.

16. The article of any one of the preceding claims, wherein the metal silicate comprises one or more of an alkali metal or alkaline earth silicate; the metal oxide comprises one or more of aluminum trihydrate (ATH), zinc oxide (ZnO), iron oxide, titanium dioxide (TiCh), copper oxide, zirconium oxide, manganese oxide, nickel oxide, silver oxide, vanadium oxide, bismuth oxide;and the water-soluble caustic agent comprises one or more of: NaOH, KOH, or Na2O(SiO2),Li2O(SiO2), K2O(SiO2), or ammonium hydroxide.

17. The article of any one of the preceding claims, wherein the aqueous formulation further comprises a pigment that can form covalent bonds with the metal silicate and / or metal oxide / hydroxide upon forming the geopolymer.

18. The article of any one of the preceding claims, wherein the aqueous formulation further comprises one or more catalysts or activators.

19. The article of any one of the preceding claims, wherein the aqueous formulation further comprises one or more rheology modifiers.

20. The article of any one of the preceding claims, wherein the aqueous formulation further comprises one or more fibers.

21. The article of any one of the preceding claims, wherein the aqueous formulation further comprising one or more surfactants.

22. The article of any one of claims 5-21, wherein the fire resistant layer has a thickness in the range of 1 mil to 50 mils.

23. The article of any one of the preceding claims, wherein the fiber reinforced polymer comprises glass fibers in a thermoset matrix.

24. The article of claim 23, wherein the thermoset matrix comprises a polyurethane, polyester, epoxy, or any combination thereof.

25. A process for forming a fire resistant layer on or near a surface of a fiber reinforced polymer article, the process comprising:applying an aqueous formulation directly on the article; and curing the aqueous formulation into the fire resistant layer on the article; orapplying an aqueous formulation onto a sheet; curing the aqueous formulation to form a geopolymer sheet; and applying the geopolymer sheet to the article;wherein the aqueous formulation comprises geopolymer forming components of: (1) a metal silicate; (2) a metal oxide / hydroxide; (3) a water-soluble caustic agent; and (4) water; and wherein the aqueous formulation has a solids content of less than 10 wt% of the geopolymer forming components when the aqueous formulation is at a temperature of 25 °C, and / or the aqueous formulation excludes solid particles of the geopolymer forming components having an average diameter of greater than 5 pm when the aqueous formulation is at a temperature of 25 °C.

26. The process of claim 25, wherein the process comprises applying the aqueous formulation directly on the article.

27. The process of claim 25, wherein the process comprises applying the aqueous formulation onto the sheet; curing the aqueous formulation to form the geopolymer sheet; and applying the geopolymer sheet to the article.

28. The process of any one of claims 25-27, wherein applying the aqueous formulation comprises forming a multilayer coating, wherein each layer has a thickness in the range of 1- 50 mils.

29. The process of any one of claims 25-28, wherein applying the aqueous formulation comprises spraying the aqueous formulation as an aerosol.

30. The process of any one of claims 25-29, wherein applying the aqueous formulation comprises spraying, rolling and / or dipping the aqueous formulation on the article.

31. The process of any one of claims 25-30, wherein curing the applied aqueous formulation comprises exposing the aqueous formulation to air at a temperature of from about 5 °C to about 150 °C.

32. The process of any one of claims 25-31, wherein the aqueous composition has a viscosity ranging from about 25 cP to about 2,000 cP as measured by cup and bob viscosity measurement.

33. The process of any one of claims 25-32, wherein the aqueous formulation has a solids content of less than 5 wt% of the geopolymer forming components when the aqueous formulationis at a temperature of 25 °C, and / or the aqueous formulation excludes solid particles having an average diameter of greater than 3 pm of the geopolymer forming components when the aqueous formulation is at a temperature of 25 °C.

34. The process of any one of claims 25-33, wherein the aqueous formulation is a solution of the geopolymer forming components at 25 °C.

35. The process of any one of claims 25-34, wherein the aqueous formulation has a pH of no less than 9.

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