FIRE-RETARDED CELLULOSE MATERIAL

FIELD OF THE INVENTION

[0001] Embodiments of the invention relate to fire-retarded cellulose products produced by applying a liquid acid fire retardant composition comprising an aqueous solution of one or more inorganic acids as the sole or, in embodiments, the principal flame retardant component, in combination with the application of an alkali or alkaline earth compound(s) as a pH modifier, and methods of producing cellulose insulation and other products.

BACKGROUND OF THE INVENTION

[0002] Cellulose is the framework (skeleton) for all plant fibers. After harvesting, retting and drying, the cellulose fibers from trees and plants such as cotton, flax, hemp, kenaf and jute, among others, are used to manufacture paper, insulation, building products, containers and many other items. Many of these products benefit from and/or have higher value by being fire retarded. With some products it is mandatory that they are fire retarded. An example of a mandated fire retarded product is a building material such as, but not limited to, cellulose insulation.

[0003] Burning or combustion of cellulose fiber materials such as paper, cardboard, etc., generally involves two different chemical processes: a) flaming, which results from ignition of gases released by the pyrolysis of the cellulose fiber, and b) smolder, a slow, high temperature, flameless combustion which results from the oxidation of the remaining carbon-rich material, as with charcoal in a barbeque.

[0004] Cellulose insulation is flammable and prone to smoldering. However, specific chemical additions to a paper material will increase its resistance to burning. Some chemicals will extinguish flaming but not smoldering combustion. Examples of such flame-only extinguishing chemicals include borax pentahydrate, hydrated magnesium sulfate and aluminum trihydrate, among others. Other chemicals can extinguish both flaming and smolder. Examples of these chemicals include ammonium sulfate, ammonium phosphate and boric acid.

[0005] Cellulose insulation is required to meet federal regulations (and other government regulations) that mandate that cellulose insulation should not support burning under normal environmental conditions. The test methods that assure this property are set forth in ASTM C-739. Testing for flaming is carried out using critical radiant flux (CRF) equipment. In that test, a "pass" is achieved if the cellulose material will not support surface flame while being subjected to radiation of 0.12 watts/cm ² or less. Smolder testing is performed using a smolder box. A loss in weight of less than 15% of the original cellulose weight constitutes a "pass." In Europe, various classifications are available ranging from Category A to Category F. Chemical loadings that allow cellulose insulation to meet ASTM C-739 would also allow it to meet a Category B. To obtain a Category C listing lesser amounts of chemical are required than would be required to meet ASTM C-739.

[0006] In order to prevent flaming and smoldering combustion, most cellulose insulation is manufactured by applying fire retardant chemicals in powder form, such as hydrated borax, boric acid, ammonium sulfate, aluminum trihydrate (ATH), etc. In order to meet government standards for cellulose insulation, the loading of the powdered chemical is typically about 14% to 18%) by weight (wt%>) of the final insulation product. However, those chemicals are relatively expensive and their inclusion significantly raises the costs associated with the manufacture of a cellulose insulation product. In addition, the powder material dusts the cellulose particle surface, with a large portion of the powder being present in the product as loose dust particles. There are growing concerns about potential adverse health effects associated with the use of and exposure to borate compounds (e.g., borax, boric acid, etc.), which, although providing fire retardant and insecticidal properties, are respiratory irritants and have shown adverse reproductive effects in test animals.

[0007] By comparison, the application of a liquid form of the fire retardant chemical will penetrate the cellulose particles and requires a much lower loading of the fire retardant chemical, typically about 4 to 11 wt%> of the final insulation product. This lowers raw material cost and results in appreciable cost savings. Liquid fire retardant compositions are described, for example, in USP 4,595,414 and USP 4, 168,175 (Shutt). Examples of liquid fire retardant chemicals include aqueous solutions of ammonium sulfate, monoammonium phosphate, diammonium phosphate, ammonium tripolyphosphate, boric acid, ferrous sulfate, zinc sulfate, and mixtures thereof, dissolved in water. A disadvantage of currently known liquid fire retardant chemicals is that they can be corrosive or devolve ammonia through offgassing. In addition, as discussed above, exposure to borate compounds has been linked to potential adverse health effects.

[0008] Corrosion under insulation (CUI) is corrosion that develops over time beneath thermal insulation used, for example, on pipes, tanks and various manufacturing and process equipment. CUI typically results from condensation, rainwater, cleaning fluids, etc., that seep in and permeate into the insulation and onto the underlying substrate. Impurities and temperature gradients at the metal surface can lead to concentration of corrosive species (e.g., salts) that subsequently causes corrosion and damage to the substrate.

[0009] Accordingly, it would be desirable from an industry standpoint to provide a cellulose material that would overcome the foregoing disadvantages. It would also be desirable to produce such a cellulose material at a low cost, with liquid chemical as the sole or, in embodiments, the principal flame retardant, which will possess the requisite level of fire retardance to meet various government standards.

SUMMARY

[0010] The present invention provides a fire-retarded cellulose fiber material and cellulose products, and methods of production.

[0011] The present invention provides a chemistry and method of making a fire retarded cellulose material that meets governmental standards in both the EU and US for flame, smolder, corrosion, smell and mold while at the same time controlling pH of the paper. Borates and ammonium salts (the two most common chemicals used for this purpose) are undesirable components for any part of the present formulations.

[0012] While achieving all the foregoing criteria above, the present invention utilizes raw materials that not only have fire retardant properties but are also not harmful to the earth (i.e., eco-friendly), and effectively interact with each other to produce the desired end results. In addition, the components that are used enable the dust by-product to be used in creating products such as soil amendments and other mulch products that contain a value-added fertilizer component. The present formulations and methodology can be consistently and effectively run in a factory on a commercial scale and at a lowered cost compared to other known systems. [0013] Embodiments of this invention relate to manufacturing a fire-retarded cellulose insulation that is both highly effective and economical. The cellulose insulation material incorporates liquid acid fire retardant technology so as to enable it to be effectively dedusted as the cellulose dust commonly found in other cellulose-based insulation is highly undesirable. In preferred embodiments, the fire-retardant raw materials that are used to produce the cellulose insulation material (alone or as a reaction product with other raw material(s)) can be utilized as a mulch product which comprises a fertilizer component. This is highly important as it enables the dust by-product to be useful in creating mulch products such as soil amendment products or mulch containing a fertilizer component. In embodiments, the mulch product is composed of cellulose dust and a fertilizer component. In embodiments, the fertilizer component of the mulch product is comprised of sulfuric acid, phosphoric acid and magnesium sulfate as the reaction product of sulfuric acid and calcium magnesium carbonate (CaMg(C0 ₃ ) ₂ ), e.g., dolomite), and optionally, unreacted calcium magnesium carbonate (e.g., dolomite).

[0014] In embodiments, the present compositions (formulations) and manufacturing techniques create two highly functional and useful products from one manufacturing process (i.e., a fire-retarded cellulose insulation product and a mulch product comprising a fertilizer component (e.g., fertilizer, soil amendment, etc.). In embodiments, another important criterion is that the fire-retardant formulation contains no borates or ammonium salts as borates have been found to be harmful to male reproductive health and ammonium salts have been known to have off-gassing issues.

[0015] In an embodiment, the fire-retarded cellulose fiber material is produced by applying a liquid acid fire retardant composition comprising an aqueous solution of inorganic acid(s) as the sole or principal flame retardant component to a cellulose material, and an alkali or alkaline earth compound(s) as a pH modifier (e.g., Na ₂ C0 ₃ , CaMg(C03)2, CaC0 ₃ ) such that the cellulose material has a pH of about pH 3.5 to 7, and de-dusting the dried cellulose material to eliminate an amount of dust.

[0016] The liquid acid fire-retardant composition is an aqueous solution that is applied to the cellulose fiber material to provide fire-resistance. In embodiments, the liquid acid fire-retardant composition is composed of an aqueous solution of one or more inorganic acids. In embodiments, the liquid acid fire retardant composition consists of an aqueous solution of one or more inorganic acids. In a preferred embodiment, the inorganic acid is selected from the group consisting of sulfuric acid, phosphoric acid, and mixtures thereof. The liquid acid fire-retardant composition can further include optional non-fire retardant additives such as a surfactant. In embodiments, the liquid acid fire-retardant composition composed of inorganic acid(s) (e.g., sulfuric acid, phosphoric acid, and mixtures thereof) is the sole fire retardant chemical component of the cellulose material.

[0017] In an embodiment, an aqueous solution of an alkali compound(s) or aqueous slurry of an alkaline earth compound(s) is applied to the cellulose material as a pH modifier prior to the de-dusting step, or in other embodiments, after the de-dusting step. In another embodiment, a powdered alkali or alkaline earth compound(s) is applied as a pH modifier to the cellulose material after the de-dusting step. In another embodiment, both (a) an aqueous solution of an alkali compound(s) or aqueous slurry of an alkaline earth compound(s) and (b) a powdered alkali or alkaline earth compound(s) are applied as a pH modifier to the cellulose material.

[0018] In an embodiment, an effective amount of an aqueous solution of an alkali compound(s) or aqueous slurry of an alkaline earth compound(s) is added to the acid-treated cellulose material to reduce the free acid and increase the pH of the cellulose material to a pH of 3.5 to 7 (e.g., to inhibit paper degradation). In embodiments, the resulting cellulose product comprises a salt resulting from the reaction of the inorganic acid(s) and alkali or alkaline earth compound(s), which is absorbed and/or adhered to the cellulose fibers.

[0019] In an embodiment, an effective amount of a powdered alkali or alkaline earth compound(s) is added to the acid-treated cellulose material to, initially and over time, react with a portion of the inorganic acid component of the cellulose material to modify and/or maintain the pH of the cellulose material at about pH 3.5 to7.0 (e.g., to inhibit paper degradation) while maintaining an effective amount of the unreacted inorganic acid(s) component to provide the cellulose material with a requisite level of fire retardancy. The amount of powdered alkali or alkaline earth compound(s) is also sufficient to maintain a residual amount of the powdered alkali or alkaline earth compound(s) in the fire-retarded cellulose fiber material in an unreacted latent (or dormant) form to react with water (or other aqueous solution) to raise the pH of the cellulose material to about pH 5 to 7.5, or about pH 6 to 7, in the event that the cellulose material (e.g., installed insulation) is brought into contact with an aqueous solution (e.g., due to a flooding or leakage event, etc.) to inhibit or prevent corrosion under insulation (CUI) of underlying metal parts, structures and materials.

[0020] In an embodiment, the method of producing a fire-retarded cellulose fiber material according to the invention comprises the steps of:

applying a solution of a liquid acid fire-retardant composition to a cellulose material to produce a wetted, fire retardant-treated cellulose material, wherein the liquid acid fire-retardant composition comprises a) a fire retardant chemical component consisting of an aqueous solution of one or more inorganic acids; and b) optionally, one or more additives;

drying the wetted, fire retardant-treated cellulose material to produce a dried, fire retardant-treated cellulose material having the fire retardant chemical component absorbed therein and/or dried thereon;

reducing the dried, fire retardant-treated cellulose material in size to produce a reduced size, fire-retarded cellulose fiber material; and

removing a major amount of dust material from the reduced size, fire-retardant cellulose fiber material to produce a reduced-dust, fire-retarded cellulose fiber material;

wherein the method comprises at least one of the following:

a) prior to removing the dust material, applying an amount of an aqueous solution of an alkali compound or an aqueous slurry of an alkaline earth compound to the wetted and/or the dried, fire retardant-treated cellulose material to adjust the pH of the cellulose material to a pH of 3.5 to 7; and/or b) after removing the dust material from the reduced size, fire-retarded cellulose fiber material, applying an amount of an aqueous solution of an alkali compound or an aqueous slurry of an alkaline earth compound to the reduced dust, fire-retarded cellulose material to adjust the pH of the cellulose material to a pH of 3.5 to 7; and/or c) after removing the dust material from the reduced size, fire-retarded cellulose fiber material, applying an amount of a powdered alkali compound or alkaline earth compound to the reduced dust, fire-retarded cellulose fiber material such that the reduced dust, fire-retarded cellulose fiber material is at a pH of 3.5 to 7.

[0021] In embodiments, an amount of an aqueous solution of an alkali compound(s) or aqueous slurry of an alkaline earth compound(s) is added to the acid-treated cellulose material to increase the pH of the cellulose material to a pH of 3.5 to 7 (e.g., to inhibit paper degradation). In embodiments, the resulting cellulose product comprises a salt resulting from the reaction of the inorganic acid(s) and alkali or alkaline earth compound(s), which is absorbed and/or adhered to the cellulose fibers. In embodiments, the acid-derived salt is a sulfate or a phosphate.

[0022] In embodiments, an amount of a powdered alkali or alkaline earth compound is added to the de-dusted cellulose material to react with the inorganic acid(s) (initially and over time) to maintain the cellulose material at a pH of 3.5 to 7, while maintaining an effective amount of the unreacted inorganic acid component to provide the requisite level of fire retardancy. The amount of the powdered alkali or alkaline earth compound within the cellulose material is also sufficient such that when (or if) water or other aqueous solution contacts the fire-retarded cellulose fiber material, corrosion (CUI) of the underlying material or substrate is substantially inhibited or prevented by reaction of the aqueous solution with the alkali or alkaline earth powdered compound within the cellulose material to raise and maintain the pH at about 5 to 7.5, or about pH 6 to 7.

[0023] In an embodiment, the invention is a fire-retarded cellulose fiber material comprising cellulosic fibers and inorganic acid(s) absorbed therein and/or dried thereon, and an alkali compound(s) or alkaline earth compound(s) absorbed to, adhered to and/or dispersed within the cellulose fiber material. In an embodiment, the fire-retarded cellulose fiber material is a de-dusted material. In preferred embodiments, the inorganic acid(s) consists of or, in other preferred embodiments, consists essentially of phosphoric acid or as a mixture of phosphoric acid and sulfuric acid. In an embodiment, an alkali compound(s) (e.g., sodium carbonate, Na ₂ C0 ₃ , soda ash) is applied to the cellulose material. In an embodiment, an alkaline earth compound(s) (e.g., calcium carbonate (CaC0 _3; e.g., limestone) and/or calcium magnesium carbonate (CaMg(C0 ₃ ) ₂ ), e.g., dolomite)) is applied to the cellulose material [0024] In an embodiment, the dried, de-dusted fire-retarded cellulose fiber material (product) (e.g., insulation) has a pH of 3.5 to 7, or 4.5 to 7, and comprises, based on the total weight of the cellulose fiber material:

a) cellulosic fiber, at from 80, or 85, or 90, up to 94, or 96, or 98, wt%;

b) an inorganic acid(s) or salt thereof, at from 1, or 1.5, or 2, or 4, up to 5, or 10, or 12, wt%;

c) an alkali or alkaline earth compound(s), at from 0.5, or 2, or 3, or 5, up to 12, or 12, or 19, wt%; and

d) optionally, a surfactant(s), at from 0, or 0.05, up to 0.1, or 0.2, wt%.

[0025] In embodiments, the alkali or alkaline earth compound(s) is absorbed to, adhered to and/or dispersed within the cellulose fiber material.

[0026] In an example embodiment, the fire retardant cellulose fiber material comprises, based on the total weight of the cellulose fiber material, 98 to 80 wt% of cellulose fiber, 1 to 12 wt% of an organic acid(s), 0.5 to 19 wt% of an alkali or alkaline earth compound, and 0 to 0.2 wt% surfactant.

[0027] In embodiments, the cellulose material includes an amount of a powdered alkali or alkaline earth compound to maintain at least a residual amount of the alkali or alkaline earth compound dispersed within the fire retarded cellulose fiber material in an unreacted latent (or dormant) state to react with water (or other aqueous solution) that may contact the fire retardant cellulose fiber material such that the pH of the cellulose fiber material is increased and/or maintained at about 5 to 7.5, to inhibit or prevent corrosion (CUI) of underlying metal parts, structures and materials.

[0028] In an embodiment, the sole flame retardant component of the fire-retarded cellulose material is the applied aqueous solution of inorganic acid(s).

[0029] In embodiments, the fire retardant cellulose fiber material is without the presence of an ammonium salt or ammonia residue therefrom. In embodiments, the fire retardant cellulose fiber material is without the presence of borates. [0030] The cellulose fiber material produced according to the disclosure possesses the requisite level of fire retardance to meet government standards. In embodiments, the cellulose fiber material has a CRF value of 0.12 watts/cm ² or greater, as measured according to

ASTM C-739. In embodiments, a fire resistant cellulose insulation material has a settled bulk density of 1 to 2 lbs/ft ³ .

[0031] Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as reaction conditions, and so forth as used in the specification and claims are to be understood as being modified in all instances by the term "about."

[0032] As used herein, the term "liquid acid fire retardant composition" and like terms, means an aqueous solution composed solely of one or more inorganic acids as the fire-retardant chemical component, without organic acids or powdered fire-retardant chemicals. A liquid acid fire retardant chemical composition can optionally include one or more non-fire retardant additives (e.g., surfactants).

[0033] "Composition" and like terms mean a mixture or blend of two or more components.

[0034] As used herein, the term "fire" refers to the process of burning of cellulose by flame or smolder. The terms "flame" and "flammable" refer to the burning of gases resulting from pyrolysis due to heat. The term "smolder" or smoldering combustion refers to the burning of a carbon-rich material remaining after gases have devolved (e.g., as with charcoal in a barbeque). Both burning processes can be chemically tested by the methods, for example, as outlined in ASTM C-739 (Standard Specification for Cellulosic Fiber Loose-Fill Thermal Insulation) and as mandated by law.

[0035] The term "fire-retardant chemical" refers to a chemical substance or mixture (other than water) that reduces flammability or smolder of a cellulose material. The term "fire retarded composition" or "fire retardant" cellulose material, and like terms, refers to a composition or material having reduced flammability or smolder.

[0036] Unless stated to the contrary, implicit from the context, or customary in the art, all parts and percentages are based on weight. DESCRIPTION OF THE INVENTION

[0037] In embodiments, the present invention relates to a fire-retarded cellulose fiber (e.g., paper-based) product composed of an absorbed inorganic acid component as a majority weight percent (wt%) of the fire retardant compound, an alkali or alkaline earth compound absorbed in, adhered to and/or dispersed within the cellulose fiber material, wherein the material has a pH of 3.5 to 7, or pH 4.5 to 7, and methods of producing the cellulose product.

[0038] The inclusion of the inorganic acid(s) component provides an effective flame retardant in the cellulose material. However, the low pH of the inorganic acid(s) within the cellulose results in degradation of the cellulose material and potential corrosion of metal substrates on which the cellulose material is applied (e.g., as insulation) due to contact with water or other aqueous solution. Typically, the application of inorganic acids such as sulfuric and phosphoric acid results in a cellulose material having a pH of between 2.5 and 3.2.

According to the invention, in embodiments, the problem of degradation of the cellulose material and corrosion of metal substrates is rectified by the addition of a liquid and/or powdered alkali or alkaline earth compound(s).

[0039] In embodiments, the invention applies a liquid acid fire retardant composition consisting of an aqueous solution of one or more inorganic acids as a majority weight percent (wt%) of the fire retardant component to cellulose fiber to produce a fire retardant cellulose fiber material composed of cellulosic fibers containing the liquid acid fire-retardant composition absorbed therein and/or dried thereon. In embodiments, before and/or after de-dusting the dried cellulose material, an amount of an aqueous solution of an alkali compound(s) or an aqueous slurry of an alkaline earth compound(s) can be applied to the acid-treated cellulose material such that the pH is 3.5 to 7. In embodiments, after the de-dusting step, a powdered alkali or alkaline earth compound(s) can be incorporated into the de-dusted fire retarded cellulose fiber material to produce a fire-retarded cellulose product having a pH of 3.5 to 7. In embodiments, both a) an aqueous solution of an alkali compound(s) or an aqueous slurry of an alkaline earth

compound(s), and b) a powdered alkali or alkaline earth compound(s), are applied to the cellulose material. [0040] In embodiments, an effective amount of a powdered alkali or alkaline earth compound(s) is added to increase or maintain the cellulose material at a pH of 3.5 to 7 over time and, upon contact of the fire retardant cellulose fiber material with an aqueous solution (e.g., water), to increase and maintain the cellulose material at a pH of 5 to 7.5, to inhibit or prevent corrosion under insulation (CUI) of underlying metal parts, structures and materials. In embodiments, powdered calcium carbonate (CaCC _, e.g., limestone) or powdered calcium magnesium carbonate (CaMg(C0 ₃ ) ₂ ), e.g., dolomite) are applied to the dried fire retardant cellulose fiber material as the powdered alkali or alkaline earth compound(s).

[0041] The cellulose product of the invention possesses a high level of fire resistance at a much lower cost than other cellulose-based products. In embodiments, the products and methods of the invention avoid the use of powdered (dry) fire retardant compositions.

[0042] In embodiments, in fabricating the cellulose product, no dry powdered fire retardant compounds need to be applied to or included in the cellulose material. The use of an aqueous inorganic acid solution as the sole fire retardant component of the liquid acid fire retardant composition (without the inclusion of organic acids or powdered fire retardant compounds) can lower costs in the manufacturing of the cellulose product, e.g., insulation, and also eliminate potential problems of corrosiveness and odor, which can occur in the use of conventional powdered fire retardants.

[0043] Processes for applying liquid fire-retardant compositions to cellulose materials are known in the art, as described, for example, in U.S. Patent No. 5,534,301 (Shutt).

Shredder

[0044] Briefly, a supply of cellulose-containing material can be loaded onto a feed table where the cellulose material can be sorted and separated from non-cellulose materials, and then conveyed into a shredding apparatus to physically reduce the cellulose material to a desired size (e.g., pieces of paper), for example, a typical average width and length of 0.5 to 2 inches (1.25 to 5 cm). Cellulose-containing materials typically comprise wood or other plant materials, for example, cotton, flax, hemp, kenaf and jute, among others, known and used in the art for producing cellulose-based materials, for example but not limited to, unused or used (recycled) paper such as newspaper, cardboard, fiberboard, paperboard, etc. The shredding apparatus may involve different types of standard systems known in the art.

Spray Booth

[0045] In embodiments, the liquid acid fire retardant composition is then applied to wet (moisten) the reduced size cellulose material. In a preferred embodiment, the liquid acid fire retardant composition is delivered in a spray booth using a spraying system that can include one or more spraying nozzles connected to a source of the liquid acid fire retardant composition, e.g., a tank. Spray booths are well known in the art. The liquid acid fire retardant composition can be delivered onto the cellulose material in a fine mist composed of a plurality of droplets (e.g., droplets 40 to 200 microns in diameter). Application of the liquid acid fire retardant composition produces a fire retardant shredded cellulose material that is moistened (wetted) with the liquid acid fire retardant composition.

[0046] For some applications, immersion of the reduced size cellulose material in the liquid acid fire retardant composition is preferred, for example, when manufacturing insulation blankets from fibers such as flax and jute for use in the automobile market. In such an application, the reduced size cellulose material can be immersed in a bath containing the liquid acid fire retardant composition, and then dried. Optionally, to remove excess liquid prior to drying, the cellulose material can be passed through a dewatering device such as a vacuum screening apparatus or rollers.

Liquid acid fire retardant chemical

[0047] Although acids are destructive to paper, it was surprisingly found that the application of an aqueous solution of one or more inorganic acids onto a cellulose material, without the application of a conventional, powdered fire retardant chemical such as hydrated borax, ammonium sulfate, aluminum trihydrate (ATH), etc., will render the cellulose material fire resistant to both flame and smolder combustion. Although not intended to be a limitation to the present disclosure, it is believed that the inorganic acid hydrolyzes the cellulose material through the donation of a proton (H ⁺ ), which causes breaking of the covalent bonds that hold the glucose rings together, which in turn leads to a reaction (under heat) that provides a flame retarding effect and increases the fire resistance of the cellulose product, e.g., insulation. [0048] In general, the liquid acid fire retardant chemical composition can comprise any inorganic acid which imparts fire resistance to the cellulose materials. Preferred acids are those that are non-toxic. Examples of suitable acids include strong inorganic acids such as sulfuric acid and weak inorganic acids such boric acid and phosphoric acid. In embodiments, the liquid acid fire-retardant composition is composed of an aqueous solution of one or more inorganic acids as the sole fire retardant chemical component.

[0049] In preferred embodiments, the inorganic acid is sulfuric acid, phosphoric acid, or a mixture thereof. In embodiments, the liquid acid fire retardant composition is an aqueous solution comprising a fire retardant chemical component that consists of at least one of sulfuric acid and phosphoric acid. The liquid acid fire-retardant composition can further include optional non-fire retardant additives such as a surfactant.

[0050] In embodiments, the liquid acid fire-retardant composition is an aqueous solution consisting of phosphoric acid as the fire-retardant component. In embodiments, the liquid acid fire-retardant composition is an aqueous solution consisting of sulfuric acid as the fire-retardant component. In embodiments, the liquid acid fire-retardant composition is an aqueous solution consisting of sulfuric acid as the fire-retardant component.

[0051] In embodiments, the liquid acid fire-retardant composition comprises a fire retardant component that consists of an aqueous solution of sulfuric acid or phosphoric acid. In embodiments, the liquid acid fire-retardant composition comprises a fire retardant component that consists of a mixture of a major amount of sulfuric acid and a minor amount of phosphoric acid (i.e., less than 50 wt.% phosphoric acid based on the total weight of the inorganic acids). In embodiments, the liquid acid fire-retardant composition comprises a fire retardant component that consists of an aqueous solution of a mixture of a major amount of phosphoric acid and a minor amount of sulfuric acid (i.e., less than 50 wt.% sulfuric acid of the total weight of the inorganic acids).

[0052] In an embodiment, the liquid acid fire-retardant composition is an aqueous solution of the inorganic acid(s) as the sole fire retardant chemical component (i.e., without organic acids or powdered fire retardant chemical compounds), and optional additives. In embodiments, the concentration of the inorganic acid in the liquid acid fire-retardant composition (with optional additives) is greater than zero (>0), more typically at least 1.5 wt%, more typically at least

1.8 wt%, more typically at least 2 wt%, more typically greater than 2 wt%, more typically at least 5 wt%, more typically at least 10 wt%, more typically at least 15 wt%, up to 50 wt%, more typically up to 40 wt%, more typically up to 30 wt%, more typically up to 25 wt%, and more typically up to 20 wt%, based on the total weight of the liquid acid fire-retardant composition. In a preferred embodiment, sulfuric acid is present as the acid component in the liquid acid fire-retardant composition as a 15 wt% to 25 wt% aqueous solution, preferably as a 20 wt% aqueous solution.

[0053] In embodiments, the liquid acid fire retardant chemical comprises an effective amount of the inorganic acid such that its application alone or in combination with an alkali or alkaline earth compound will provide a cellulose material with a Critical Radiant Flux (CRF) value of at least 0.12 watts/cm ² , which will pass testing requirements, for example, the requirements according to ASTM C-739 (Standard Specification for Cellulosic Fiber Loose-Fill Thermal Insulation). For example, as illustrated by the test data in Table 1 below, a cellulose material that was sprayed with 15 wt% inorganic acid ("acid load") from a 40 wt% aqueous inorganic acid solution had a "passing" CRF value (i.e., at least 0.12 W/cm ² ) except for the 40% glycolic acid application.

Table 1

[0054] The CRF values indicate the minimum radiant energy needed for a fire to sustain flame propagation, with a higher number indicating a more flame-resistant system, i.e.,

>0.45 W/cm ² being better than 0.42 or 0.12 W/cm ² . A "pass" is achieved if the cellulose material will not support surface flame while being subjected to radiation of 0.12 watts/cm ² or less.

[0055] The results in Table 1 demonstrate the effectiveness of an inorganic acid as a flame retarding additive to cellulose material. The data also demonstrates that stronger inorganic acids (e.g., sulfuric acid, phosphoric acid) are more effective in flame retarding ability than weaker organic acids (e.g., acetic acid, citric acid).

Additives

[0056] In order to enhance the wetting or impregnation of the cellulosic fiber material by the liquid acid fire retardant composition, a conventional wetting agent or surfactant may be included in the solution, such as a polyoxyethylene alkyl phenol, e.g. TRITON X-100

(manufactured by Rohm & Haas Co.). In embodiments utilizing a wetting agent or surfactant, the liquid acid fire-retardant composition generally comprises 0.02 to 0.2 part of one or more wetting agents or surfactants, more typically 0.04 to 0.1 part, and more typically 0.1 part, based on 100 parts of water.

Application of liquid fire-retardant composition

[0057] In applying the liquid acid fire-retardant composition, it was found that the better the coverage of the cellulose material by the acid, the less acid is required to pass the CRF test. This was determined by spraying a liquid acid fire-retardant composition having a lower acid content/higher water content, which provided greater area coverage of the pieces of the cellulose material than a liquid acid fire-retardant composition having a higher acid content, e.g., a 40% versus a 10% aqueous solution of sulfuric acid (H ₂ S0 ₄ ). This is illustrated by the test data summarized in Table 2 below, generated by using an aqueous solution of different

concentrations of sulfuric acid (H ₂ S0 ₄ ) applied to the cellulose material by spraying the shredded, size-reduced cellulose material in a spray booth. Table 2

Sulfuric Acid

(aqueous solution) Acid Load (wt %f CRF (W/cm ² )

(% by wt)

40 6.65 0.16

20 6.65 0.22

10 6.65 0.28

[0058] The application of the liquid acid fire-retardant composition preferably produces a wetted/moistened cellulose material that comprises an amount of the composition such that the wetted fibers contain at least 4 parts up to 12 parts, and more typically up to 8 parts of the inorganic acid as the fire resistant chemical per 100 parts of the cellulose fibers. The amount of inorganic acid that is applied will vary according to the acid, its strength and its dilution in aqueous solution, and should be sufficient to provide a CRF value of at least 0.12 W/cm ² , including, in embodiments, after the application of the alkali solution or alkaline earth slurry to the acid-treated fibers to form an acid-derived salt, or after the application of a powdered alkali or alkaline earth compound.

Dwell time

[0059] In embodiments, after the application of the liquid acid fire-retardant composition, a "dwell" time (delay period) is allowed to elapse in order to ensure diffusion of the liquid fire retardant composition into the cellulose fibers (and reaction of the alkali or alkaline earth compound to adjust the pH of the product, e.g., to 2.5, or to 3.5 to 8). For example, the wetted cellulose material can be held in a hopper or other containment vessel for a desirable time period, for example, up to 45 seconds to 120 seconds (up to 2 minutes) or longer, and in embodiments, from 2 to 15 minutes.

Drying

[0060] After the application of the liquid acid fire retardant, the wetted cellulose material is dried to remove the added water from the applied liquids. Removal of the excess water through drying reduces the amount of dust produced in subsequent processing through the hammermill and/or fiberizer. In embodiments, the wetted cellulose material is transferred by a stream of air (e.g., heated air) into a drying chamber such as a rotary drier and a tumble drier, among others. In preferred embodiments, the dried cellulose material is "air dry" (e.g., 90 to 95% dry) having a 5% to 10% moisture content.

Fiberizer/Hammer mill

[0061] The dry, fire retardant-treated cellulose material can then be transferred, for example, by air flow, to a hammer mill, fiberizer or both, such as known and used in the art, to further reduce the size of the shredded material into smaller pieces, for example to an average length and width of 0.25 to 0.5 inches (0.6 to 1.25 cm). In embodiments, the cellulose material can be dried, for example, by applying heat to the wetted material prior to or during the transfer of the material.

[0062] Fiberizers and hammer mills are known and used in the art. The fiberizer, for example, is a mechanical device configured with rotating elements in close proximity to one or more sets of static or counter rotating elements such that when the cellulose material is conveyed through the device, a finely divided material is produced. Processing through the fiberizer reduces the size of the cellulose material to a desired, final reduced size, fluffy form. For a cellulose insulation product, it is preferred that the final product will have a settled bulk density of 1 to 2 lbs/ft ³ (e.g., 1.2 to 1.6 lbs/ft ³ ).

Dedusting

[0063] The size reduction processing in the fiberizer/hammer mill typically produces a substantial quantity of dust (i.e., material with very small particle size), which contains residues and chemicals that can be easily inhaled and pose significant problems such as lack of visibility and personal nuisance due to a high amount of air-borne dust particles, particularly when the material is pneumatically applied, for example, as an insulation.

[0064] In embodiments, the fire-retardant cellulose fiber material can be de-dusted to eliminate a major amount (i.e., at least 50% by volume or more) to substantially all (i.e., about 90-100%) by volume) of the dust, and produce a low-dust fire-retardant cellulose fiber material that has functionally equivalent fire-retardant properties as the fire-retardant cellulose fiber material before de-dusting. The de-dusted product can be characterized by a substantial absence of detached fibrous residue which, if present, can increase its density.

[0065] Such a dust removal (de-dusting process is described in US 2010/0086780 (Shutt) (issued as USP 9,045,605). The de-dusting can be performed by any suitable process, for example, by screening, air classification, or other known separation techniques. Preferably, the de-dusting is performed by a screening technique or screening in combination with another separation technique.

[0066] In preferred embodiments, the screen has a mesh size that is suitable for effectively separating a sufficient amount of dust from the dried product, preferably to produce a substantially dust-free material by removing at least about 50% by volume of the dust content of the dried product, more preferably at least about 70%, and more preferably at least 90%, up to 100%), by volume of the dust. The mesh of the screen can range from about 200 mesh to about 10 mesh, and is preferably about 40 mesh to about 14 mesh, more preferably about 30 mesh to about 20 mesh.

[0067] In embodiments, the de-dusting removes about 15 to 30 wt%>, or 15 to 25 wt%> of the overall weight of the final product.

[0068] In embodiments, a reduced-size dry cellulose product that has been processed according to the invention using a liquid fire-retardant chemical, will typically contain about 15-25 % by weight (wt%>) dust composed of about 85-96 wt%> cellulose-based (e.g., paper) dust with about 15-4 wt%> of fire-retardant chemical adhered to the dust, and de-dusting according to the invention can remove a substantial amount of dust (up to 100%> of the dust) from the reduced-size dry product with substantially no loss of fire-retardant properties.

Pest Control Additive

[0069] In embodiments, a minor amount of a pest control additive can be added to the dried cellulose material after the size reduction step. For example, about 1 to 15 wt of a pest control additive can be added to the dried cellulose material, the wt%> based on the total weight of the cellulose material. For example, although not preferred, a powdered boric acid or salt thereof (e.g., sodium borate, borax) can be applied to the dried, acid-treated cellulose fiber in a minor amount, e.g., 1 to 5 wt% based on the total weight of the cellulose material, as a pest control additive (e.g., insecticide). The pest control additive can be added in the bagger bin just before the cellulose material is bagged.

Application of Alkali Compound(s) or Alkaline Earth Compound(s)as pH modifier

[0070] The application of the inorganic acid to the cellulose material will generally cause the material to degrade. In addition, the use of inorganic acid as a flame retardant can lead to problems of metal corrosion upon use, e.g., after a cellulose insulation product is installed.

[0071] To counteract the degradation of the cellulose material and eliminate problems with corrosion during use, a liquid, aqueous solution of an alkali compound(s) or aqueous slurry of an alkaline earth compound(s), and/or a powdered alkali compound(s) or alkaline earth

compound(s) can be applied to the acid-treated cellulose material. The application of an alkali compound or alkaline earth compound onto the acid-treated cellulose material can counteract the hydrolytic activity by the acid(s) and modify the acidity of the cellulose material by increasing the pH, which can prevent an excessive degradation of the paper.

[0072] Preferred alkali compounds are those with high water solubility. Non-limiting examples of alkali compounds suitable for use include sodium carbonate, sodium hydroxide, potassium hydroxide, potassium carbonate, and mixtures thereof. Preferred alkali compounds include sodium carbonate and sodium hydroxide. Non-limiting examples of alkaline earth compounds include magnesium carbonate, calcium carbonate (e.g., limestone), calcium magnesium carbonate (e.g., dolomite), and mixtures thereof.

[0073] Although not preferred, in embodiments, a mixture of an alkali compound(s) and an alkaline earth compound(s) is applied to the cellulose material.

[0074] Treatment of the acid-treated cellulose material with an aqueous alkali solution or alkaline earth slurry will result in the production of the corresponding salt of the acid (i.e., acid-derived salt, or salt derivative), for example, sulfates and phosphates.

[0075] In embodiments, an aqueous solution of a water-soluble alkali compound(s) or aqueous slurry of an alkaline earth compound(s) (other than a sulfate) can be applied to the acid- treated, cellulose material. The application of the alkali solution or alkaline earth slurry preferably produces a wetted/moistened cellulose material that comprises an amount of the alkali or alkaline earth compound sufficient to adjust the cellulose material to a pH of at least 3.5, or at least 4, or at least 5, up to a pH of 8, or a pH of 7, or a pH of 6.

[0076] In embodiments, an aqueous solution of an alkali compound or aqueous slurry of an alkaline earth compound is applied onto the acid-treated cellulose material to modify the cellulose material to a pH of 3.5 to 7. In embodiments, the aqueous solution of the alkali compound or aqueous slurry of the alkaline earth compound is applied to the acid-treated cellulose material in amount effective to react with a portion of the acid component to modify the acidity of the cellulose material to pH 3.5 to 7, while retaining a portion of unreacted acid in a latent form within the cellulose material to provide a requisite level of flame retardancy to the cellulose material.

[0077] In some embodiments, in applications of a liquid acid fire-retardant composition containing greater than (>) 2 wt% of the inorganic acid (e.g., sulfuric acid and/or phosphoric acid), an aqueous alkali solution or aqueous alkaline earth slurry can be applied to the acid-treated cellulose material to moderate the pH of the acid-treated cellulose material to a pH of 3.5 to 7.

[0078] In some embodiments, in applications of a liquid acid fire-retardant composition containing greater than (>) 0 wt% to less than or equal to (<) 2 wt% of the inorganic acid (e.g., sulfuric acid and/or phosphoric acid), application of an aqueous alkali solution or aqueous alkaline earth slurry to the acid-treated cellulose material may not be required to moderate the pH of the material.

[0079] In embodiments, an aqueous solution of a water-soluble alkali or aqueous slurry of an alkaline earth compound can be sprayed onto the cellulose material after the application of the liquid acid fire-retardant composition. In embodiments, an aqueous alkali solution or alkaline earth slurry can be applied after a delay period to allow the acid to react with the cellulose fibers, generally after a 2 to 15 minute delay period. The amount of alkali or alkaline earth compound that is applied will vary according to the alkali or alkaline earth compound, its concentration in aqueous solution or aqueous slurry, and the acid(s) and amount of acid(s) applied. [0080] In embodiments, the aqueous solution of the water-soluble alkali compound or the aqueous slurry of the alkaline earth compound comprises at least a 5 wt%, more typically at least a 10 wt%, more typically at least a 15 wt%, up to 25 wt%, of the alkali or alkaline earth compound. In an embodiment, sodium carbonate is used as the alkali component as a 5 to 20 wt% aqueous solution, preferably as a 15 wt% aqueous solution. In a preferred embodiment, calcium magnesium carbonate (CaMg(C03) ₂ ), e.g., dolomite), is used as the alkaline earth component as a 5 to 20 wt% aqueous slurry, preferably as a 15 wt% aqueous slurry.

[0081] In an embodiment, an aqueous alkali solution or alkaline earth slurry is applied prior to removing the dust material from the cellulose material (i.e., after a de-dusting step). In another embodiment, an aqueous alkali solution or alkaline earth slurry is applied after removing the dust material from the cellulose material.

[0082] In embodiments, an alkali or alkaline earth compound(s) (e.g., dolomite, limestone, etc.) is applied in powder form to the dedusted, reduced-size, fire-retarded cellulose material. The addition of a powdered alkali or alkaline earth compound(s) to the dried, dedusted cellulose material counteracts the degradation of the cellulose material and eliminates problems with corrosion of metal substrates by the application of the inorganic acid(s) liquid component to the cellulose material.

[0083] In embodiments, the powdered alkali or alkaline earth compound(s) is added to the acid-treated cellulose material in a stoichiometric amount to form a salt with all of the inorganic acid(s), minus 2% of the total weight, i.e., to form a salt with 98 wt% of the remaining inorganic acid(s).

[0084] As an example, for an acid-treated cellulose material containing 6.2 wt% sulfuric acid (H ₂ S0 ₄ ), less 2% would be 4.2 wt% H ₂ S0 ₄ . An example of the addition of a

stoichiometric amount of a powdered alkaline earth compound, for example, calcium carbonate (CaC0 ₃ ), to the acid-treated cellulose material to form the salt component, i.e., calcium sulfate (CaS0 ₄ ),would be as follows:

4.2% H ₂ S0 ₄ + 4.3% CaCo ₃ = 6.6% CaS0 ₄ [0085] In embodiments, addition of the powdered alkaline earth compound will result in a rise in the pH of the acid-treated cellulose material, for example, to pH 3.5 to 7, or to pH 4.5 to 7, thereby inhibiting degradation of the cellulose material.

[0086] Combining an aqueous solution or slurry of an alkali or alkaline earth compound(s) with the cellulose product can result in a reaction of the alkali or alkaline earth compound(s) with the inorganic acid(s) component to increase the pH of the cellulose material and neutralize the inorganic acid(s) component, thereby reducing the efficacy of the inorganic acid(s) component as a fire retardant. To avoid diminishing the efficacy of the inorganic acid(s) component as a fire retardant while, at the same time, reducing acid degradation of the cellulose material, a dry powdered alkali or alkaline earth compound is added to the reduced-size, dedusted, dry cellulose product to increase and/or maintain a pH level at around 3.5 to 7. The addition of alkali or alkaline earth compound(s) in a dry powdered results in only a portion of the alkali or alkaline earth compound(s) reacting with the inorganic acid(s), with the remainder of the powdered alkali or alkaline earth compound(s) remaining in the cellulose material in an unreacted latent (or dormant) state.

[0087] In an embodiment, a dry powdered alkali and/or alkaline earth compound can be introduced via an inlet feeder and blended with the reduced-size, dedusted, dry cellulose material such that the powdered alkali or alkaline earth compound is incorporated into the cellulose material.

[0088] In an embodiment, the powdered alkali or alkaline earth compound(s) is applied in an amount such that a portion of the powdered alkali or alkaline earth component will initially react with a portion of the inorganic acid(s) component to raise the pH of the cellulose material to about 3.5 to 7, and a portion of the powdered alkali and/or alkaline earth component and a portion of the inorganic acid(s) component will be maintained in an unreacted latent (or dormant) form.

[0089] In an embodiment, the amount of the powdered alkali and/or alkaline earth compound is sufficient, initially and overtime, to react with the inorganic acid(s) of the cellulose material to modify and/or maintain the cellulose material at a pH of about 3.5 to 7 (e.g., to inhibit paper degradation), while the efficacy of the inorganic acid(s) is maintained within the cellulose material to provide the requisite level of fire retardancy, e.g., an effective amount of the inorganic acid(s)) component is maintained in an unreacted form.

[0090] In an embodiment, the amount of the powdered alkali or alkaline earth compound is also sufficient to maintain a residual amount of the compound in the cellulose material in an unreacted latent (or dormant) form such that upon contact of the cellulose material with water (or other aqueous solution) (e.g., due to a flooding or leakage event, etc.), the pH of the cellulose material will be increased to about pH 5 to 7.5 by reaction of the aqueous solution with the powdered alkali or alkaline earth compound. With the increase in the pH of the cellulose material, corrosion under insulation (CUI) of underlying metal parts, structures and materials is substantially inhibited or prevented.

[0091] In embodiments, the fire-retarded, reduced-size, dedusted, dry cellulose product is composed of about 2 to 5 wt% of powdered alkali or alkaline earth compound(s) dispersed within the cellulose fiber material.

[0092] In embodiments, powdered calcium carbonate (CaCC^ _, e.g., limestone) or powdered calcium magnesium carbonate (CaMg(C0 ₃ ) ₂ ), e.g., dolomite) are incorporated into the reduced-size, dedusted, dry cellulose product.

[0093] In embodiments, the powdered alkaline earth compound(s) is composed of 0 to 100 wt% calcium carbonate (e.g., limestone) and/or 0 to 100 wt% calcium magnesium carbonate (e.g., dolomite).

[0094] In embodiments, the powdered alkaline earth compound(s) is a mixture of calcium carbonate (e.g., limestone) and calcium magnesium carbonate (e.g., dolomite).

[0095] In embodiments, the powdered alkaline earth compound(s) is a mixture of about 0.1 to 99.9 wt% calcium carbonate (e.g., limestone) and about 99.9 wt% to 0.1 wt% calcium magnesium carbonate (e.g., dolomite), the wt% amounts based on the total weight of the powdered alkaline earth compound(s). In embodiments, the powdered alkaline earth

compound(s) comprises calcium carbonate (e.g., limestone) in an amount of at least 0.1, or 1, or 5, or 10, or 20, or 30, or 40, or 50, wt%, up to 99.1, or 99, or 95, or 80, or 70, or 60, or 50, wt %, of the wt% amounts based on the total weight of the powdered alkaline earth compound(s). In embodiments, the powdered alkaline earth compound(s) comprises calcium magnesium carbonate (e.g., dolomite) in an amount of at least 0.1, or 1, or 5, or 10, or 20, or 30, or 40, or 50, wt%, up to 99.1, or 99, or 95, or 80, or 70, or 60, or 50, wt %, the wt% amounts based on the total weight of the powdered alkali and/or alkaline earth compound(s).

[0096] In embodiments, the use of a powdered alkali compound provides for relatively rapid pH control of the dried, dedusted, acid-treated cellulose material (e.g., a pH of about 3.5 to 7), but at a relatively high cost with the use of some alkali compounds. By comparison, in embodiments, the use of a powdered alkaline earth compound can provide for a relatively slow reaction with the inorganic acid(s) component of the dried, dedusted, acid-treated cellulose material whereby the desired pH (e.g., a pH of about 3.5 to 7) is achieved over a longer period of time. It was found that the incorporation of either a powdered alkali compound or a powdered alkaline earth compound into the dried, dedusted, acid-treated cellulose material provides a reaction with water (or other aqueous solution) in contact with the cellulose material that achieves the desired pH (e.g., a pH of about 6 to 8) at a relatively fast rate, as in the corrosion test set forth in ASTM-C-739 or, for example, in the occurrence of a leak in the roof or other like event.

Mulch

[0097] In embodiments, the dust generated from the de-dusting step can be processed into pellets for use as a mulch product, for example, to fertilize the soil, hydroseeding, and/or as a soil attenuation product, among other uses.

[0098] In embodiments, the cellulose dust by-product derived from de-dusting a cellulose material treated according to the invention with sulfuric acid and/or phosphoric acid as the inorganic acid(s) component, and a powdered alkaline earth component, is eco-friendly and suitable for use as a mulch product (e.g., a fertilizer, seed carrier, etc.) and other agricultural purposes.

[0099] In embodiments, the dust component is composed of cellulose and a fertilizer component comprising, in embodiments, sulfuric acid, phosphoric acid, and magnesium sulfate (produced by reaction of dolomite with sulfuric acid), and in embodiments, unreacted dolomite. [00100] In an embodiment, the dust powder by-product resulting from the de-dusting step can be optionally mixed, for example, with a binder such as water, nutrients, seeds, dyes and/or other optional additives. The composition can be fed into a conventional pellet mill, pelietized (e.g., size ranging from granular to large pellets), and air-dried to a desired water content. The pelietized material can then be deposited into a holding bin or conveyed to a bagging apparatus, as known and used in the art, and packaged for transport and future use.

Final Product / Packaging

[00101] In an embodiment, the final fire-retarded cellulose product, e.g., insulation, based on the total weight of the product, comprises:

A. Cellulose fibers, being at least 80 wt%, more typically at least 85 wt%, more typically at least 90 wt%, up to 94 wt%;

B. One or more inorganic acids, at up to 10 wt%, and at least 1 wt%, or at least

4 wt% (e.g., sulfuric acid and/or phosphoric acid), applied as a 10 to 40 wt% aqueous solution and then dried on the material;

C. One or more alkali or alkaline earth compound(s) (e.g., Na ₂ C0 ₃ , CaC0 ₃ ,

CaMg(C0 ₃ ) ₂ ), at up to 10 wt%, or up to 8 wt%, or up to 5 wt%, or up to 4 wt%, or more typically up to 2 wt%; and

D. Optionally, a surfactant, typically up to 0.2 wt%.

[00102] The foregoing fire-retarded cellulose product meets government regulations governing fire and flame retardance, smolder, smell, mold and corrosion for insulation products.

[00103] In embodiments, the fire retardant cellulose fiber material is without the presence of an ammonium salt or ammonia residue therefrom. In embodiments, the fire retardant cellulose fiber material is without the presence of boric acid or borate salt.

[00104] In embodiments, the final cellulose product is treated with an amount of the inorganic acid component sufficient and effective to provide a level of fire retardance to meet government standards for both the smoldering combustion test and the flame spread burn test, which for insulation is outlined, for example, in ASTM C-739 (Standard Specification for Cellulosic Fiber Loose-Fill Thermal Insulation). [00105] In embodiments, the cellulose fiber material has a CRF value of 0.12 watts/cm ² or greater, as measured according to ASTM C-739. In embodiments, the final cellulose product is treated with an amount of the inorganic acid component sufficient and effective to provide a level of fire retardance sufficient to attain a Category B listing or higher in Europe.

[00106] The dried cellulose product can be deposited into a holding bin or conveyed to a bale press or baler or to a bagging apparatus, as known and used in the art, and packaged for transport and future use. In an installation process for insulation, the fire retarded cellulose insulation product can be placed into a hopper and mechanically fluffed-up, and then "blown" directly into an attic or stud spaces in an existing wall, among other applications.

[00107] The fire-retarded cellulose product of the invention can be used for producing fire-retarded products including building materials such as but not limited to cellulose insulation, fire doors and cellulose-based board materials (e.g., panels), as well as automotive fabrics, and furniture, among other articles.

[00108] In embodiments of the present invention, fire resistance of the cellulose product is imparted, solely or partially, by the presence of an inorganic acid(s) component, which is applied to the cellulose material exclusively as a liquid (without the presence of an organic acid or powdered fire retardant chemicals).

[00109] The present cellulose insulation and other products and materials possess the required level of fire retardance to meet government standards for both the smoldering combustion test and the flame spread burn test, and further meets government regulations for corrosion, smell, and mold. The elimination of fire retardant chemicals such as hydrated borax, ammonium sulfate, aluminum trihydrate (ATH), etc., significantly lowers manufacturing costs, avoids outgassing of ammonia, and eliminates potential health issues associated with the use of boric acid/borates.

[00110] In embodiments of the present invention, the only chemical used for imparting fire resistance is an inorganic acid(s), which is applied to the cellulose material exclusively as a liquid (without the presence of an organic acid or powdered fire retardant chemicals).

Surprisingly, the applied liquid acid fire retardant composition (and, in embodiments, the subsequently applied alkali or alkaline earth compound) provides a cellulose insulation and other products having the required level of fire retardance to meet federal standards for both the smoldering combustion test and the flame spread burn test, while significantly reducing the cost of manufacture of the fire-retarded cellulose material, e.g., insulation, compared to cellulose material produced using only a powdered or other liquid fire retardant chemical. The use of an aqueous inorganic acid component (in some embodiments as the sole fire retardant chemical) in place of more expensive fire retardant chemicals such as hydrated borax, ammonium sulfate, aluminum trihydrate (ATH), etc., significantly lowers manufacturing costs, avoids outgassing of ammonia, and eliminates potential health issues associated with the use of boric acid/borates.

[00111] Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement which is calculated to achieve the same purpose may be substituted for the specific embodiments shown. This application is intended to cover any adaptations or variations that operate according to the principles of the invention as described. Therefore, it is intended that this invention be limited only by the claims and the equivalents thereof. For purposes of United States patent practice, the contents of any referenced patent, patent application or publication are incorporated by reference in their entirety.