Fire resistant lumber coated with geopolymer and assemblies of the same

Abstract

Lumber including dimensional lumber and assemblies thereof can have a fire resistant coating on at least one surface thereof. The fire resistant coating can be prepared from an aqueous formulation including geopolymer forming components of: (1) one or more metal silicates, (2) one or more metal oxides / 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, large solid particles comprised of the metal silicate, metal oxide / hydroxide and water-soluble caustic agent.

Description

FIRE RESISTANT LUMBER COATED WITHGEOPOLYMER AND ASSEMBLIES OF THE SAME CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and all benefit of U.S. Provisional Application No.63 / 740,283, filed December 30, 2024, the entire disclosure of which is fully incorporated herein by reference.TECHNICAL FIELD

[0002] The present disclosure is directed to lumber and assemblies thereof having a fire resistant (FR) barrier coating prepared from geopolymer forming components dissolved in an aqueous formulation.BACKGROUND

[0003] Wood products are used throughout the construction and transportation industry because of wood’s sustainability, versatility, and functional performance at relatively low costs. Wood is a structural organic material - a natural composite composed of cellulose fibers that are bound together in a matrix of lignin which is a natural phenolic polymer. Wood also refers to materials engineered from wood or its derivatives such as woodchips or fiber.

[0004] Lumber is wood that has been altered by one or more processes. For example, lumber may be processed by cutting, debarking, milling, sawing, planing, sanding, edging, shaping, or combinations thereof. Lumber includes beams, planks and boards. Lumber is often used for construction framing (e.g., joists, studs, beams, girders, purlins, rafters, and trusses) and floors, wall panels, window frames, etc. In North America, wood that has been processed into uniform sizes is called dimensional lumber. Dimensional lumber may be supplied either rough-cut or as finished lumber (e.g., planed, sanded, shaped surfaces on one or more of its faces). The term lumber also includes timber. Timber may be used to refer to wood that is largely unprocessed from its natural state (e.g., debarking and / or cutting). Examples of timber include felled trees and poles or posts.

[0005] A use of dimensional lumber is wooden pallets for transport of goods. The global wood pallet market is estimated at over several billion dollars and growing. However, lumber can be limited by its inherent flammability and assemblies such as wooden pallets can bum, risking damage to goods stored thereon as well as risking damage to transport containers, warehouses, and potentially personnel.

[0006] Also in a dry environment such as that in a climate controlled warehouse, lumber loses moisture over time, leading to reduction in mechanical properties. Conversely, in an outdoor (or wet) environment, lumber can take on excess moisture, which could lead to accelerated aging and certain deterioration of the lumber and items constructed therefrom.

[0007] Accordingly, there is a continuing need to improve the fire resistance of dimensional lumber and structures assembled from lumber.SUMMARY OF THE DISCLOSURE

[0008] Advantages of the present disclosure include fire resistant lumber and assemblies thereof that can include one or more thin coatings of geopolymer prepared from an aqueous formulation with low non-dissolved (or undissolved) solids content and / or substantially free of large solid particles. Coatings prepared from the aqueous formulation of the present disclosure can also advantageously improve weather-resistance and / or corrosion resistance of the underlying lumber and / or prevent moisture gain or loss by the lumber, minimizing aging and certain deterioration of the lumber and items constructed therefrom.

[0009] In certain aspects, lumber and assemblies thereof having a fire resistant coating on at least one surface thereof is 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. 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. An advantage of the aqueous formulation of the present disclosure is that it generally can have a low 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 formulation and limiting the size of solid particles in the aqueous formulation allows the aqueous formulation to be applied as one or more thin layers and / or applied by a liquid atomizer and / or a 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 formulation to allow formation of thin coating layers of geopolymer from such a formulation.

[0010] In still further 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. The 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.

[0011] Advantageously, the fire resistant coating can be formed on lumber such as dimensional lumber and timber and assemblies thereof such as pallets.

[0012] In other aspects, a fire resistant coating can be formed from aqueous formulations of the present disclosure by applying the formulation onto lumber, e.g., on one or more or on all surfaces of the lumber, or on surfaces of an assembly of the lumber, and drying the applied aqueous formulation to cure the formulation into a fire resistant coating on the lumber or assembly thereof. Advantageously, the aqueous formulation can be applied by spraying the formulation onto lumber. The spray may be applied as an aerosol or by an airless sprayer. Alternatively, or in addition thereto, the aqueous formulation can be applied by dip coating, rolling, brushing, etc. Further, the aqueous formulation can be applied to form one or more coating layers in which each layer can have a thickness in the range of 1- 50 mils (25 pm to 1,270 pm). In some implementations, the applied aqueous formulation can be cured in air at a temperature of from about 5 °C to about 50 °C or can be cured by exposing the applied aqueous formulation to heat at a temperature of from about 50 °C to about 500 °C.

[0013] Implementations of the present disclosure include one or more of the following features individually or combined. For example, the lumber can comprise dimensional lumber or timber. The Lumber may be kiln dried lumber, pressure treated lumber, flame treated lumber, sealed lumber, or any combination thereof. In some aspects, the timber can be a utility pole, cross arm, railroad tie, etc. The assembly of lumber can be configured as a pallet comprising a top deck fastened to stringer boards or blocks. Alternatively, the assembly of lumber can be configured as floor beams, joists, roof girders, trusses or frames, wall framing, columns and braces, window and door frames, indoor architectural features such as shelving, hearth, and decorative feature, etc., or outdoor assemblies such as gazebos and pergolas, etc.

[0014] In other aspects, the aqueous formulation 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 components may or may not be soluble in the aqueous formulation and may be solid components of the aqueous formulation.

[0015] 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: aluminum trihydrate (ATH), 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 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 any combination thereof.

[0016] 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

[0017] Reference is made to the attached drawings, wherein elements having the same reference numeral designations represent similar elements throughout and wherein:

[0018] FIG. 1 A illustrates an assembly of lumber configured as a pallet, in particular, a stringer pallet.

[0019] FIG. IB illustrate an assembly of lumber configured as a pallet, in particular, a block pallet.

[0020] FIG. 2 illustrates images of samples of coated and uncoated lumber according to aspects of the present disclosure.

[0021] FIG. 3 illustrate images of the samples shown in FIG. 2 after exposure to a burn test.

[0022] FIG. 4 illustrates the configuration of the bum test for the samples shown in FIG. 2.DETAILED DESCRIPTION OF THE DISCLOSURE

[0023] The disclosure may be more fully appreciated by reference to the following description, including the following definitions and examples. Certain features of the disclosed formulations and compositions and methods which are described herein in the context of separate aspects, mayalso be provided in combination in a single aspect. Alternatively, various features of the disclosed formulations and methods that are, for brevity, described in the context of a single aspect, may also be provided separately or in any sub-combination.

[0024] 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.

[0025] As employed above and throughout the disclosure, the following terms and abbreviations, unless otherwise indicated, shall be understood to have the following meanings.

[0026] 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.

[0027] 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.

[0028] The present disclosure is directed to fire-resistant coatings on lumber and assemblies of lumber. As used herein, lumber refers wood that has been altered by one or more processes. For example, lumber may be processed by cutting, debarking, milling, sawing, planing, sanding, edging, shaping, or combinations thereof. Lumber may optionally be treated. Treated lumber includes air dried lumber, kiln dried lumber, pressure treated lumber, chemically treated lumber, flame treated lumber, sealed lumber, etc. Lumber treatment can be of any of the individual methods listed above, or a combination thereof. . Lumber is often used for construction framing (e.g., joists, studs, beams, girders, purlins, rafters, and trusses) and floors, wall panels, window frames, etc. Lumber includes dimensional lumber, which is characterized as wood cut and milled to specific sizes. The term lumber also includes timber. Timber may be used to refer to wood that is largely unprocessed from its natural state (e.g., debarking and / or cutting). Examples of timber include felled trees and poles or posts. In some aspects, the timber can be a utility pole, cross arm, railroad tie.

[0029] Dimensional lumber includes rough cut lumber, surfaced one side lumber “SIS”, surfaced two sides lumber “S2S”, surfaced three sides lumber “S3S”, surfaced four sides lumber “S4S”, and straight line ripped lumber “SLR”.

[0030] In certain aspects, the dimensional lumber may be characterized by the length, width, and / or thickness of the lumber. For example, the dimensional lumber may have a length of at least 1 cm, at least 3 cm, at least 5 cm, at least 10 cm, at least 20 cm, at least 30 cm, at least 40 cm, at least 50 cm, at least 60 cm, at least 70 cm, at least 80 cm, at least 90 cm, at least 100 cm, at least 120 cm, at least 150 cm, at least 180 cm, at least 200 cm, at least 210 cm, at least 240 cm, and at least 250 cm. The dimensional lumber may have a length of at most 800 cm, at most 760 cm, at most 750 cm, at most 730 cm, at most 700 cm, at most 670 cm, at most 640 cm, at most 610 cm, at most 580 cm, at most 550 cm, at most 520 cm, at most 550 cm, at most 520 cm, at most 500 cm, at most 490 cm, at most 460 cm, at most 430 cm, at most 400 cm, at most 370 cm, at most 350 cm, at most 320 cm, and at most 300 cm. In some aspects, dimensional lumber may have a length ranging from at least 1 cm to at most 800 cm and any values therebetween.

[0031] In certain aspects, in addition to, or as an alternative to the length and / or width, the dimensional lumber may be characterized by the thickness or height of the lumber. The dimensional lumber may have a thickness of at least 1 mm, at least 1.5 mm, at least 2 mm, at least 2.5 mm, at least 3 mm, at least 5 mm, at least 6 mm, at least 9 mm, at least 10 mm, at least 12 mm, at least 15 mm, at least 18 mm, at least 21 mm, at least 25 mm, at least 31 mm, at least 38 mm, at least 44 mm, and at least 50 mm. The dimensional lumber may have a thickness of at most 305 mm, at most 280 mm, at most 254 mm, at most 229 mm, at most 203 mm, at most 191 mm, at most 178 mm, at most 165 mm, at most 152 mm, at most 140 mm, at most 127 mm, at most 114 mm, at most 102 mm, at most 89 mm, at most 76 mm, at most 70 mm, at most 64 mm, and at most 57 mm. In some aspects, dimensional lumber may have a thickness ranging from at least 1 mm to at most 305 mm and any values therebetween.

[0032] In certain aspects, in addition to, or as an alternative to the length and / or thickness, the dimensional lumber may be characterized by the width of the lumber. The dimensional lumber may have a width of at least 3 mm, at least 5 mm, at least 6 mm, at least 9 mm, at least 10 mm, at least 12 mm, at least 15 mm, at least 18 mm, at least 21 mm, at least 25 mm, at least 31 mm, at least 38 mm, at least 44 mm, at least 50 mm, at most 64 mm, at most 76 mm, and at most 102 mm. The dimensional lumber may have a thickness of at most 610 mm, at most 533 mm, at most 457 mm, at most 305 mm, at most 381 mm, at most 305 mm, at most 280 mm, at most 254 mm, at most 229 mm, at most 203 mm, at most 191 mm, at most 178 mm, at most 165 mm, at most 152 mm, at most 140 mm, at most 127 mm, and at most 114 mm. In some aspects, dimensional lumber may have a width ranging from at least 3 mm to at most 610 mm and any values therebetween.

[0033] Lumber can advantageously benefit from the fire resistant coatings of the present disclosure since they are typically in locations that can be susceptible to a fire event. Lumberhaving a fire-resistant coating of the present disclosure finds use as structural components of building structures, architectural, weather resistance, moisture barriers, fire resistance component structures, etc.

[0034] In addition, the lumber can be configured as an assembly of lumber, in which a fire resistant coating of the present disclosure can be on the lumber prior to assembly, or applied after assembly of the lumber, or both. Advantageously, the assembly of lumber can be configured as floor beams, joists, roof girders, trusses or frames, wall framing, columns and braces, window and door frames, indoor architectural features such as shelving, hearth, and decorative feature, etc., or outdoor assemblies such as porticos, decking, gazebos and pergolas, etc. In one aspect, the assembly of lumber can be configured as a pallet comprising a top deck fastened to stringer boards or blocks.

[0035] A pallet is a structure that is conventionally used to stack and transport goods, which can be conventionally lifted and moved by a forklift or pallet jack. There are a variety of pallets that are assembled from dimensional wood including stringer pallets and block pallets. Each of such pallets share certain common features including a top deck, formed from an array of boards or as a wooden panel, which is fastened to stringer boards (in the case of stringer pallets) or blocks (in the case of block pallets). Such pallets can also include a bottom deck formed from additional boards or panels. Pallets often have standard sizes and configurations to facilitate transportation and storage. For example, pallets may have standard sizes to allow the pallets to pass through standard-sized doorways and facilitate loading onto trucks. For example, conventional pallets may have a size of 48 inches by 48 inches, 48 inches by 42 inches, 48 inches by 40 inches, 42 inches by 42 inches, 40 inches by 40 inches, 36 inches by 36 inches, and 45.5 inches by 43 inches.

[0036] FIGS. 1 A and IB illustrate a stringer pallet and block pallet, respectively. As illustrated in FIG. 1A, stringer pallet 100 includes a top deck 102, formed from an array of boards 102a, 102b, etc. The boards configured as a top deck 102 are fastened to a set of stringer boards (104a, 104b, 104c) beneath the top deck boards. As shown in this example, the stringer boards are further fastened to a bottom deck 106, formed from several boards (106a, 106b, etc.) in which the top deck and bottom deck sandwich the stringer boards. Stringer boards are typically made out of 2x4 inch or 3x4 inch dimensional lumber.

[0037] FIG. IB illustrates a block pallet 130 includes a top deck 132, formed from an array of boards 132a, 132b, etc. which are fastened to stringer boards (133a, 133b, 133c), which in turn are fastened to blocks of wood (134a, 134b, 134c, etc.). There can be nine blocks of wood configured in a block pallet, with a solid wood block placed in each of the four corners and three block placed in the center of the pallet. The stringer boards extend the full length of a block pallet and runperpendicular to the deck boards and are located between the deck and the blocks. Block pallets can be designed with or without bottom deck boards. In the example of FIG. IB, stringer boards 135a, etc. form a bottom deck.

[0038] Advantageously, aqueous formulations of the present disclosure that can form the fire resistant coatings on lumber or an assembly thereof can be composed of relatively low cost components and can be readily applied to a surface of the lumber or an assembly thereof. The aqueous formulation form a geopolymer upon curing that can bond to the surface as it dries to form the fire resistant coatings of the present disclosure. Fire resistant coatings prepared from the aqueous formulations of the present disclosure can advantageously improve weather-resistance, moisture loss or gain of the underlying lumber.

[0039] 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.

[0040] An advantage of the aqueous formulation of the present disclosure is that it generally can have a low non-dissolved 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 coating can have a thickness of less than about 5 mm, such as less than 2 mm. For example, the fire-resistant coating can have a thickness in the range of 1 mil to 50 mils (25 pm to 1,270 pm).

[0041] 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 aqueous formulation. 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.

[0042] 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 aqueous formulation at a temperature of 25 °C.

[0043] 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.

[0044] 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.

[0045] 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 ofcellulose 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.

[0046] 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 coating. 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 silicate to 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.

[0047] 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 anycombination 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.

[0048] 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) (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, it is understood that metal oxides in aqueous solutions convert to their equivalent hydroxide, and thus the use of metal hydroxide is equivalent to use of the metal oxide (e.g., ZnO is equivalent to Zn(OH)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.

[0049] 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 Na3PO4, 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.

[0050] In some aspects, the aqueous formulations of the present disclosure have at least 95 wt% of the alkali silicate content as silicate ions in solution. This state can be determined, forexample, when a solution of the alkali silicate can be passed through a 0.5 pm filter with no remaining visible particulate residue.

[0051] 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.

[0052] 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 silicate and the metal oxide / hydroxide dissolved in, or substantially dissolved in, the formulation and combining other optional components.

[0053] Further the components can be in a kit prior to preparing the aqueous formulation in which one or more of the components are isolated from another component in the kit. The order of combining the components is not particularly limiting. Some components, however, typically take longer to dissolve in water and are thus more suited to combining as an initial step. For example, the metal silicate can be dissolved in water to form a metal silicate solution and then combined with the other components to form the aqueous formulation. Alternatively, or in combinations, the water soluble caustic agent can be dissolved in water to form a caustic agent solution and then combined with the other components. Alternatively, or in combinations, the metal silicate and caustic agent can be dissolved in water as a metal silicate-caustic agent solution and then combined with the other components to form the aqueous formulation. In some aspects, the initial (1) alkali metal silicate, (2) metal oxide / hydroxide, and / or (3) water soluble caustic agent initially can be in powder form such as finely divided powders having average powder diameters ranging from about 1 pm to about 40 pm. Such powder forms can facilitate dissolution of the components in a shortened period of time. (Typically when the powders have an average diameter of less than 1 micron, there can be viscosity increases associated with high surface areas to volume ratios.)

[0054] Further the kit can include the metal silicate solution isolated from the other components, or the caustic agent solution isolated from the other components, or the metal silicate-caustic agent solution isolated from the metal oxide / hydroxide and / or other components for forming the aqueous formulation. The kit can further include instructions for preparing the aqueous formulation according to the present disclosure and can provide instructions on how to apply the formulation to form a fire resistant coating on lumber or an assembly thereof.

[0055] 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.

[0056] In certain implementations, the prepared 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., azo dyes, etc., and / or an inorganic pigment, e.g., ultramarine blue (a complex sulfur-containing sodium-silicate), carbon black, iron oxide, titanium oxide, or copper oxide, potassium permanganate (KMnC ), sodium chromate (NaCnO-t). etc. Certain of these components may or may not be soluble in the formulation and may form solid components of 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 with 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.

[0057] In further aspects, a fire resistant coating can be formed from the aqueous formulation by applying the aqueous formulation to on lumber or an assembly thereof and drying the applied aqueous formulation on the lumber or an assembly thereof to cure the aqueous formulation into afire resistant coating on the substrate. 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 have a 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 coating 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. Advantageously, the geopolymer can bond to exposed hydroxyl groups on the lumber thereby providing a relatively strong coating on the lumber. 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 coating can be formed by applying one or more aqueous formulations of the present disclosure onto lumber or an assembly thereof. The aqueous formulations can be applied to a surface of the lumber or an assembly thereof in a variety of ways including brushing, rolling, spraying, dip coating, electrodeposition, etc. In one aspect, the aqueous formulation is applied to the lumber or an assembly thereof by spraying the aqueous formulation onto the lumber or an assembly thereof 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 multiple layers of a fire resistant coating with the same or 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 the surface of the lumber or an assembly thereof, the aqueous formulation is dry or is dried. Drying the aqueous formulation causes it to cure and 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, which can advantageously bond to the surface of the lumber. Curing the aqueous formulation can be carried out conveniently in air at ambient conditions. For example, the aqueous formulation can be cured by drying in air from a temperature range of about 5 °C to about 50 °C. Curing can be accelerated by heating at a temperature of from about 50 °C to about 500 °C in air or another gas, such as heating from 50 °C to about 500 °C, 50 °C to about 200 °C, 50 °C to about 150 °C.

[0061] In some implementations, lumber can have a fire resistant coating of the present disclosure thereon 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 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.

[0062] Advantageously, the aqueous formulations of the present disclosure can be formed on a variety of lumber or an assembly thereof.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] Example 1: Wood samples were obtained from a U.S. standard pallet, which bears a IPPC stamp showing HT (heat treated), US manufacturer code 169295, audited by TP®. Sample A was tested without a coating; Samples B, C and D were dip-coated with an aqueous formulation of the present disclosure to form a fire resistant coating. The weight of the coatings was determined by weight gain on the samples after curing the coatings. The samples had the following coating weights: B-9%, C-19%, D-39%. The aqueous formulation was prepared by adding 5 lbs. of aluminum trihydrate, 2.5 lbs. of zinc oxide, 2 lbs. of milled carbon fiber, and 0.1 lb. of sodium bicarbonate to a plastic 5 gallon bucket. The solid ingredients were then blended with a paddle into a semi-homogenous powder mix. To this bucket was added 10 lbs. of a pre-dissolved 40% aqueous solution of sodium silicate, 2 lbs. of a pre-dissolved 50% aqueous solution of sodiumhydroxide, and 1.5 lbs. of water. The blend was mixed thoroughly with a high speed bowtie shear mixer for 5 minutes.

[0065] The coatings on Samples B, C, and D were formed by dip-coating the samples in the aqueous formulation and allowed to cure at room temperature. Sample B was dip-coated and dried once, Sample C twice, and Sample D three times, respectively. FIG. 2 illustrates images of an uncoated Sample A and coated Samples B, C and D.

[0066] The prepared samples were then subjected to a burn test. FIG. 3 illustrates images of the samples after exposure to a bum test. The burn test included exposing the samples to a MAP / Pro gas torch in which the sample’s burn face was normal to horizontal, and the torch was held at a 45°-angle and approximately 2 inches from the sample. See FIG. 4. Test observations are summarized in the table below.Table 1.

[0067] These burn experiments showed the uncoated wood sample appeared to have suffered the most severe fire damage. The fire resistant coatings on the samples mostly remained intact except at some break-out locations. Further, the fire-resistant coatings on the samples significantly reduced burn intensity and flame-out time.

[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. Fire resistant lumber comprising:lumber having a fire resistant coating on at least one surface thereof, wherein the fire resistant coating is 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;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 that have an average diameter of greater than 5 pm when the aqueous formulation is at a temperature of 25 °C.

2. The fire resistant lumber of claim 1, wherein the lumber comprises dimensional lumber.

3. The fire resistant lumber of claim 1, wherein the lumber comprises kiln dried lumber, chemically treated lumber, pressure treated lumber, flame treated lumber, sealed lumber, or any combination thereof.

4. The fire resistant lumber of claim 1, wherein the lumber comprises a utility pole, cross arm, or railroad tie.

5. An assembly comprising the fire resistant lumber of claim 1.

6. The assembly of claim 5 configured as a fire resistant pallet, wherein the pallet comprises a top deck fastened to stringer boards or blocks.

7. The fire resistant lumber of any one of the preceding 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 of the geopolymer forming components that have an average diameter of greater than 3 pm when the aqueous formulation is at a temperature of 25 °C when the aqueous formulation is at a temperature of 25 °C.

8. The fire resistant lumber of any one of the preceding claims, wherein the aqueous formulation is a solution of the geopolymer forming components at 25 °C.

9. The fire resistant lumber of any one of the preceding claims, wherein the ratio of metal silicate to metal oxide / hydroxide ranges from about 5:1 to 1:5.

10. The fire resistant lumber of any one of the preceding claims, wherein at least 95 wt% of the silicate content in the aqueous formulation are silicate ions in solution.

11. The fire resistant lumber of any one of the preceding claims, wherein the metal silicate comprises at least 50 wt% sodium metasilicate based on a total weight of the metal silicate.

12. The fire resistant lumber of any one of the preceding 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; 5% to 25% of the (3) water soluble caustic agent.

13. The fire resistant lumber of any one of the preceding claims, wherein the aqueous formulation includes, based on the total weight of the aqueous formulation, 25% to 80% of the water.

14. The fire resistant lumber of any one of the preceding claims, wherein the aqueous formulation has a pH of no less than 8.

15. The fire resistant lumber of any one of the preceding claims, wherein the aqueous formulation has a viscosity ranging from about 25 cP to about 2,000 cP as measured by cup and bob viscosity measurement.

16. The fire resistant lumber of any one of the preceding claims, wherein the metal silicate comprises one or more of: an 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.

17. The fire resistant lumber 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.

18. The fire resistant lumber 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), Li2O(SiC>2), K2O(SiC>2), ammonium hydroxide, or any combination thereof.

19. The fire resistant lumber 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.

20. The fire resistant lumber of any one of the preceding claims, wherein the aqueous formulation further comprises a pigment that can covalently bond to the metal silicate and / or metal oxide / hydroxide upon forming the fire resistant coating.

21. The fire resistant lumber of any one of the preceding claims, wherein the aqueous formulation includes an inorganic pigment selected among one or more of ultramarine blue, iron oxide, titanium oxide, copper oxide, or any combination thereof.

22. The fire resistant lumber of any one of the preceding claims, wherein the aqueous formulation further comprises one or more catalysts or activators.

23. The fire resistant lumber of any one of the preceding claims, wherein the aqueous formulation further comprises one or more rheology modifiers.

24. The fire resistant lumber of any one of the preceding claims, wherein the aqueous formulation further comprises one or more fibers.

25. The fire resistant lumber of any one of the preceding claims, wherein the aqueous formulation further comprises one or more ceramic particles.

26. The fire resistant lumber of any one of the preceding claims, wherein the aqueous formulation further comprising one or more surfactants.

27. The fire resistant lumber of any one of the preceding claims, wherein the fire resistant coating comprises one or more layers formed from one or more of the aqueous formulation, wherein each of the one or more layers has a thickness in the range of 1 mil to 50 mils (25 pm to 1,270 pm).

28. The fire resistant lumber of any one of the preceding claims, wherein the fire resistant coating comprises at least a first layer and a second layer, each of which is formed from one or more of the aqueous formulation, wherein the first layer has a composition that is different from the second layer.

29. A process for forming a fire resistant coating, the process comprising:applying an aqueous formulation onto lumber or an assembly of lumber; andcuring the aqueous formulation to form the fire resistant coating on the lumber or assembly thereof;wherein the aqueous formulation includes geopolymer forming components of (1) a metal silicate; (2) a metal oxide / hydroxide; (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.

30. The process claim 29, wherein applying the aqueous formulation comprises forming one or more layers of the fire resistant coating, wherein each layer has a thickness in the range of 1-50 mils (25 pm to 1,270 pm).

31. The process of claim 29 or claim 30, wherein applying the aqueous formulation comprises spraying the aqueous formulation to form the fire resistant coating.

32. The process of either claim 29 or 30, wherein applying the aqueous formulation comprises rolling, brushing, and / or dipping one or more of the aqueous formulation.

33. The process of any one of the preceding claims, wherein curing the applied aqueous formulation comprises exposing the applied aqueous formulation to air at a temperature of from about 5 °C to about 50 °C.

34. The process of any one of the preceding claims, wherein curing the applied aqueous formulation comprises exposing the applied aqueous formulation to heat at a temperature of from about 50 °C to about 500 °C.

Images