Flame retardant composition and preparation thereof

Abstract

The present invention provides a method for producing a flame-retardant composition containing hemicellulose and lignin components, as well as its use.

Description

Technical Field

[0001] The present invention relates to the technical field of flame retardants, and particularly relates to a flame retardant composition containing lignin and hemicellulose residues and a method for preparing the flame retardant composition.

Background Art

[0002] Conventional halogen-based flame retardants have the advantage of a good flame retardant effect, but release a large amount of toxic gases when burned, which causes great harm to human health and the environment.

[0003] Among halogen-free flame retardant alternatives, phosphorus-based flame retardants are widely used because of their low smoke, low strength, and no generation of corrosive gases. Furthermore, flame retardants containing both phosphorus and nitrogen have low toxicity and better thermal stability, and phosphorus and nitrogen have a synergistic flame retardant effect. However, although current common flame retardants have excellent flame retardant properties, their synthetic raw materials are non-biodegradable and mainly based on increasingly depleted petrochemical resources. Therefore, large-scale production and use will have a negative impact on the environment.

[0004] The preparation of biodegradable, sustainable, and environmentally friendly flame retardants has important social significance and economic value.

Summary of the Invention

[0005] The present invention provides a simple method for manufacturing a flame retardant, and provides a flame retardant composition having an excellent flame retardant effect and produced from a sustainable source at the same time. Furthermore, the flame retardant component is soluble in water, and thus can be applied as an environmentally harmless aqueous formulation to many substrates. In a first aspect, the present invention provides a method for preparing a flame retardant composition containing a hemicellulose component and a lignin component from plant materials, the method comprising: (i) a step of providing plant materials, wherein the plant materials are selected from cereal straws and grasses, the step of providing; (ii) A process of mechanically dry-treating plant material in order to reduce its size, (iii) A step of suspending the plant material in an aqueous solution, (iv) A step of adjusting the pH to alkaline conditions, raising the temperature of the suspension, and stirring the suspension, thereby dissolving and / or dispersing the hemicellulose and lignin components in the aqueous solution, wherein the hemicellulose and lignin components are derived from plant material. (v) A step of separating the material obtained in step (v) into a solid fiber fraction and a liquid flame retardant fraction, wherein the liquid flame retardant fraction is a flame retardant composition comprising dissolved and / or dispersed hemicellulose and lignin components.

[0006] This method optionally further includes a step of concentrating the liquid flame retardant composition to increase the dry matter content percentage.

[0007] In one preferred embodiment, the method includes an additional step of adding a flame retardant additive to the liquid flame retardant composition from step (v) or a concentrated sample of the liquid flame retardant composition from step (v). The flame retardant additive further enhances the flame retardant effect of the composition. In one embodiment, the flame retardant additive is a smoke suppression compound. Preferably, the flame retardant additive is selected from iron oxide, calcium carbonate, and expansive graphite. Therefore, in one embodiment, the present invention provides a method for preparing a flame-retardant composition containing hemicellulose and lignin components from plant materials, and this method is (i) A step of providing plant material, Here, the plant material is selected from grain straw and grass, and the process of providing it is as follows: (ii) A process of mechanically dry-treating plant material in order to reduce its size, (iii) A step of suspending the plant material in an aqueous solution, (iv) A step of adjusting the pH to alkaline conditions, raising the temperature of the suspension, and stirring the suspension, thereby dissolving and / or dispersing the hemicellulose and lignin components in the aqueous solution, wherein the hemicellulose and lignin components are derived from plant material. (V) A step of separating the material obtained in step (v) into a solid fiber fraction and a liquid flame retardant fraction, wherein the liquid flame retardant fraction is a flame retardant composition containing dissolved and / or dispersed hemicellulose and lignin components, (vi) Optionally, a step of concentrating the liquid flame retardant composition to increase the dry matter content percentage, (vii) a step of adding a flame retardant additive to the liquid flame retardant composition from step (v) or from step (vi).

[0008] In one embodiment, the hemicellulose and lignin components are dissolved and / or dispersed in step (iv) by raising the temperature to over 80°C and adjusting the pH to 9-12.

[0009] In one embodiment, the average particle size of the plant material resulting from dry mechanical processing is less than 1 cm.

[0010] In one embodiment, the suspended plant material in step (iii) is enzymatically treated with one or more hemicellulase enzymes such as xylanase and / or ferulate esterase.

[0011] Preferably, the ratio of hemicellulose and lignin components in the flame retardant composition obtained by the method of the present invention is 40:60 to 60:40, based on dry matter content.

[0012] In one embodiment, the flame retardant composition contains at least 60%, 70%, 80%, or 90% hemicellulose and lignin components based on total dry matter content.

[0013] In one embodiment, the flame retardant composition contains at least 90% hemicellulose and lignin components based on its total dry matter content.

[0014] In one embodiment, the plant material suspended in the aqueous solution in step (iii) is dewaxed grain straw, for example, dewaxed grain straw obtained by a method comprising the following steps: (a) enzymatically treating the grain straw suspended in the aqueous solution in step (iii) with a protease and / or pectinase enzyme; (b) optionally subjecting the mixture obtained in step (a) to wet mechanical treatment; and (c) removing the wax from the solution before adjusting the pH and raising the temperature in step (v).

[0015] In a second aspect, the present invention provides a flame retardant composition comprising dissolved and / or dispersed hemicellulose and lignin components in a ratio of 40:60 to 60:40 based on dry matter content. This flame retardant composition can be obtained by the method of the present invention disclosed herein.

[0016] In one embodiment, the hemicellulose component of the flame retardant composition comprises a monomer, oligomer, and / or polymer of arabinoxylan, and the lignin component of the flame retardant composition comprises monomethoxylated (guaiacyl (G)), dimethoxylated (syringyl (S)), and nonmethoxylated (p-hydroxyphenyl (H)) phenylpropanoids.

[0017] In one embodiment, the flame retardant composition contains at least 60%, 70%, 80%, or 90% hemicellulose and lignin components based on total dry matter content.

[0018] In one embodiment, the hemicellulose component and the lignin component constitute at least 90% of the total dry matter content of the aqueous composition.

[0019] In one embodiment, the flame retardant composition further comprises a flame retardant additive for further enhancing the effect of the flame retardant composition. In one embodiment, the flame retardant additive is a smoke suppression compound. In one preferred embodiment, the flame retardant additive is selected from iron oxide, calcium carbonate, and expandable graphite.

[0020] In a third aspect, the present invention relates to the use of an aqueous composition comprising a dissolved and / or dispersed hemicellulose component and lignin component as a flame retardant. This aqueous composition can be obtained by the method of the present invention disclosed herein.

[0021] In one embodiment, the aqueous composition is applied to an article by brushing or spraying the composition onto the surface of the article, immersing the article in the composition, and / or impregnating the article with the composition, such as by vacuum pressure impregnation.

[0022] In a fourth aspect, the present invention relates to the use of an aqueous composition comprising a dissolved and / or dispersed hemicellulose component and lignin component for improving the fire resistance of articles, such as solid wood elements, wood-based composites, and / or thermal insulation materials based on wood fibers, cotton, flax, hemp, sisal, jute, which are other natural fibers. This aqueous composition can be obtained by the method of the present invention disclosed herein.

[0023] In one embodiment, the aqueous composition is applied to an article by spraying the composition onto the surface of the article, immersing the article in the composition, and / or impregnating the article with the composition, such as by vacuum pressure impregnation.

[0024] In a fifth aspect, the present invention provides a method for improving the fire resistance of an article, comprising applying a flame retardant composition comprising a dissolved / dispersed hemicellulose component and lignin component to the article. This flame retardant composition can be obtained by the method of the present invention disclosed herein.

[0025] In one embodiment, the flame-retardant composition is applied to an article by spraying the composition onto the surface of the article, impregnating the article with the composition, and / or impregnating the article with the composition by vacuum pressure impregnation. [Brief explanation of the drawing]

[0026] [Figure 1] This figure shows a flame retardancy test using beech wood strips. The photographs show beech wood strips impregnated with a lignin-based flame retardant, and attempts were made to ignite them using a cigarette lighter or a candle lighter. The lignin-based flame retardant was prepared by mechanical dry treatment, fractionation, protease and pectinase treatment, hemicellulase treatment, alkaline pulping treatment, and concentration by evaporation. (a) 30% dry solids concentration, (b) 15% dry solids concentration, (c) 7.5% dry solids concentration. [Figure 2] This figure shows a flame retardancy test using beech wood strips. The photograph shows beech wood strips impregnated with a lignin-based flame retardant, and attempts were made to ignite them using a cigarette lighter or a candle lighter. (a) Lignin-based flame retardant prepared by mechanical dry treatment, fractionation, protease and pectinase treatment, hemicellulase treatment, alkali pulping treatment, and concentration by evaporation. (b) The lignin-based flame retardant prepared in (a) was further oxidized at 80°C by applying 100 ml of 35% hydrogen peroxide per 2 L of flame retardant composition, with a pH of 10.5, a temperature of 80°C, and an incubation time of 2 hours. [Figure 3] Illustration of data from Mini-SBI tests on wood samples. (A) Heat generation rate. (B) Total heat generation. (C) Flame retardant growth rate. FIRAX = Commercial flame retardant (positive control); Untreated test 417 = Negative control. Tests 415 and 416 = Samples treated with the flame retardant composition of the present invention. [Figure 4]Illustration of data from Mini-SBI tests on wood samples. (A) Scale-average heat release rate HRRav(t), (B) Scale-total heat release THR(t). (C) Scale-scale FIGRA, (D) Scale-scale total smoke output TSP(t). Firax = commercially available flame retardant (positive control); untreated (test 416) = negative control. PFE1, PFE2, PFE3 = samples treated with the flame retardant composition of the present invention. [Figure 5] MDF samples (triple layer) exposed to a small gas flame test. An untreated control sample is shown at the top, and a sample of the flame-retardant composition of the present invention is shown at the bottom. (A) Front coated surface. (B) Back uncoated surface. [Figure 6] Carbon layer of plywood. A) Sample treated with the flame-retardant composition of the present invention, (B) Untreated sample. [Figure 7] The wood samples (beech wood sticks - "tongue depressors") were immersed halfway through their length in the test solution for 20 minutes, after which excess liquid was wiped off with tissue paper, and then dried in a 70°C convection oven for 45 minutes. The sticks were then tested by applying a direct flame from a candle lighter to the underside of the stick. Stick 1 = Sample 1B (lignin / hemicellulose ratio 40 / 60). Stick 2 = Sample 2B (lignin / hemicellulose ratio 40 / 60 + CaCO3 + Fe3O4). Stick 3 = Sample 2C (lignin / hemicellulose ratio 40 / 60 + CaCO3 + expandable graphite). Stick 4 = Untreated sample

[0027] Abbreviations, terms, and definitions: The term "flame retardant" refers to chemical substances and compositions that prevent or delay the further progression of ignition. They may be added to manufacturing materials such as wood, plastics, and fibrous materials, preferably wood, wood-based panels, wood and / or other plant-derived natural fibers, for example, those used for insulation in buildings. As further disclosed herein, flame retardants may be added to materials as a surface coating or by dipping and / or impregnation. The flame retardants of the present invention also include, "Plant or lignocellulose material" or "plant or lignocellulose biomass" refers to a broad and diverse group of plant parts from many species. The terms plant, lignocellulose material, and biomass are used interchangeably. The plant materials that can be used as starting materials in this invention are derived from multicellular macroscopic plants, including stems and leaves, and may be encased in a natural outer layer or epidermis covered with a waxy, waterproof protective layer.

[0028] "Grain straw" refers to the stems, leaves, and outer layers of grain plants that remain after the grain has been harvested.

[0029] "Grass" refers to (partially) ligninized grass material from the later season.

[0030] "Cellulose" refers to a polysaccharide constructed from β-D-glucose units. D-glucose (C6H12O6) is a sugar containing five hydroxyl functional groups and an aldehyde group on carbon 1. Cellulose is a linear polymer, where hydroxyl (-OH) groups form hydrogen bonds with atoms on adjacent chains to link them together, creating microfibrils. Cellulose exhibits both crystalline and amorphous regions. Many properties of cellulose depend on its degree of polymerization, i.e., the number of glucose units that make up one polymer molecule.

[0031] "Hemicellulose" often refers to a branched type of polysaccharide, derived from several sugars including xylose, mannose, glucose, galactose, rhamnose, and arabinose. Cereal straw hemicellulose is mainly composed of arabinoxylan. In this invention, the definition of hemicellulose further refers to hemicellulose-derived products such as oligosaccharides and sugar monomers derived from the hydrolysis of hemicellulose.

[0032] "Hemicellulose residue" or "hemicellulose component" refers to fractions of different degrees of polymerization derived from plant hemicellulose, which can be identified as derived from hemicellulose and released from the plant cell wall of a plant or plant part by chemical, physical, and / or enzymatic assisted treatment. Cereal straw hemicellulose component mainly contains oligomers / polymers of different degrees of polymerization derived from arabinoxylan hemicellulose.

[0033] Lignin is a complex, cross-linked racemic polymer containing various phenylpropane units. It is relatively hydrophobic and aromatic in nature. Three monolignol monomers exist that are methoxylated to varying degrees: p-coumaryl alcohol, coniferyl alcohol, and synapyl alcohol. These lignols are incorporated into lignin in the form of the phenylpropanoids p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S), respectively.

[0034] "Lignin residue" or "lignin component" refers to a fraction derived from plant lignin released from the cell walls of plants by chemical, physical, and / or enzyme-assisted treatment, and can be identified as being derived from that lignin. Cereal straw lignin components mainly consist of 1-methoxylated (guaiacyl (G)), 2-methoxylated (syringyl (S)), and non-methoxylated (p-hydroxyphenyl (H)) phenylpropanoids.

[0035] "Wax" or "waxy component" refers to all the various forms of wax that coat the surface of plant material. It is used collectively to describe the waxy components of the cuticle (cuticular wax) that covers the above-ground parts of plants, and includes wax on the surface of plants (epicticlar wax) and wax just below the surface of plants (intraepidermal wax). Waxes contain linear, very long-chain (VLC) compounds, including varying ratios of fatty acids, primary and secondary alcohols, esters, aldehydes, free fatty acids, alkanes, and ketones. In addition, cyclic compounds such as pentacyclic triterpenoids, alkylresorcinols, sterols, and steryl esters are present in the waxes of many species. Lipids that make up the cell walls of plant cells in macroscopic or microscopic (unicellular) plants are not treated as "wax" in the context of this specification.

[0036] "Dewaxed plant material" means plant material that has been treated by a method of removing / dissociating cuticle wax from the plant material, for example, when more than 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95% of the total plant wax has been removed, and the wax content is determined by the method described in Section IV of this application.

[0037] "Dry mechanical pretreatment" refers to the mechanical treatment of plant material in a dry process by cutting, shredding, grinding, milling, or similar processes, resulting in a reduction in the size of the plant material. This may include the breaking down of the wax coating and its release from the remaining plant material that has been partially dewaxed.

[0038] In the context of this specification, "wet mechanical pretreatment" refers to the mechanical treatment of plant material suspended in an aqueous phase. This may be carried out using a refiner, including, for example, refiners known from the standard paper pulp industry, such as conical and disc-type refiners, and is so-called "atmospheric refining" operated at ambient pressure or atmospheric pressure. Alternatively, wet mechanical treatment may be carried out by wet grinding to shear or crush a solid suspended in a liquid (slurry), for example, by using a toothed colloid mill.

[0039] The term "pulping" traditionally refers to the process of extracting cellulose, a fibrous material, from wood or other raw materials as a preliminary step in papermaking. The purpose of pulping is to liberate cellulose fibers from other chemicals and impurities in the wood (or other fiber source). Chemical pulping results in the extensive removal of lignin and other non-fibrous components from the wood, and alkaline pulping is the primary method used. In this invention, alkaline pulping is used to solubilize hemicellulose and lignin components from plant materials, specifically from non-woody biomass, preferably from grain straw and / or grasses, most preferably from grain straw.

[0040] "Protease" (EC3.4) is an enzyme that digests long protein chains into shorter fragments by cleaving the peptide bonds that connect amino acid residues.

[0041] Pectinase (EC3.2) is an enzyme directly involved in the breakdown of pectin.

[0042] "Hemicellulase" belongs to the carboxyl ester hydrolase (EC 3.1.1) group and includes any enzyme involved in the breakdown of hemicellulose. Feruloyl esterase (EC 3.1.1.73) is another example of "hemicellulase".

[0043] "Ligninase" refers to any enzyme involved in the breakdown of lignin, and is called a lignolytic enzyme, such as peroxidase and laccase.

[0044] "Alkaline conditions" (or "alkaline pH") means a pH greater than 7, as measured by the art obvious to those skilled in the art.

[0045] "Flame retardant additives" refer to compounds that further enhance the flame retardant effect of a flame retardant composition. Generally, such additives are substances added to delay or suppress ignition and reduce the flame diffusion rate when exposed to flame impact. Several flame retardant additives are known in the art. Flame retardant additives can enhance the effect of a flame retardant composition in various ways, such as by acting as a smoke suppressant. "Smoke suppression compounds" refer to flame retardant additives that impart smoke suppression properties to a composition. [Modes for carrying out the invention]

[0046] The present invention relates to a flame-retardant composition and a method for preparing a flame-retardant composition.

[0047] Lignocellulose plant biomass contains the most abundant raw materials available on Earth for the production of biological products. It is composed of cellulose, hemicellulose, and lignin, along with small amounts of proteins, pectin, waxes, and various inorganic compounds.

[0048] Cellulose is an important structural component of the primary cell wall of plants. It is given by the formula (C6H 10 O5) n It is an organic compound that is a polysaccharide composed of a linear chain of hundreds to thousands of β(1->4) linked D-glucose units.

[0049] Hemicellulose is one of several heteropolymers, including xylan, glucuronoxylan, arabinoxylan, glucomannan, and xyloglucan, and is present alongside cellulose in almost all plant cell walls. Hemicellulose typically (but not exclusively) has a random, amorphous structure of low strength and can be hydrolyzed by dilute acids or alkalis, as well as by numerous hemicellulase enzymes. Hemicellulose polysaccharides contain many different sugar monomers. For example, sugar monomers in hemicellulose can include xylose, mannose, glucose, galactose, rhamnose, and arabinose. Xylose is the most abundant sugar monomer in most cases, although in some plant materials, mannose may be the most abundant sugar. Not only ordinary sugars but also their oxidized forms can be found in hemicellulose, for example, glucuronic acid and galacturonic acid may be present. Cereal straw hemicellulose is mainly composed of arabinoxylan.

[0050] Lignin is a cross-linked, racemic macromolecule that is relatively hydrophobic and aromatic in its essence. Its degree of polymerization in nature is difficult to measure because it fragments during extraction, and its molecules consist of various types of substructures that appear to repeat in a disordered manner. Three monolignol monomers exist that are methoxylated to varying degrees: p-coumaryl alcohol, coniferyl alcohol, and synapyl alcohol. Lignin fills the voids within cell walls between cellulose, hemicellulose, and pectin components. It is often covalently linked to hemicellulose, thus cross-linking different plant polysaccharides, thereby conferring mechanical strength to the cell walls and even to the entire plant.

[0051] The inventors of this specification have surprisingly found that compositions containing lignin and hemicellulose residues obtained by alkali pulping of plant materials, specifically those obtained from grain straw or grasses, possess effective flame-retardant properties.

[0052] The inventors of this specification have surprisingly found that compositions containing lignin, hemicellulose, and minerals obtained by alkali pulping of plant materials, specifically those obtained from grain straw or grasses, possess effective flame-retardant properties.

[0053] Several prior art documents disclose conventional pulping of plant materials to obtain cellulose fiber fractions, particularly from woody biomass, but also from grain straw, as described in International Publication No. 2020 / 152178. However, none of the prior art documents suggest that aqueous fractions containing dissolved / dispersed hemicellulose and lignin components obtained from such pulping processes are suitable for use as effective flame retardants.

[0054] While we do not wish to be bound by theory, it is hypothesized that when flame is applied, the hemicellulose oligomers rapidly generate energy, which rapidly carbonizes the lignin components, thereby suppressing flammable gases and flame / combustion, and the carbonized layer becomes much less flammable, preventing further combustion. Furthermore, residual NaOH or KOH and silicates from the pulping reaction may further contribute to the overall fire resistance by absorbing heat or catalyzing the formation of carbonization. As shown here, isolated lignin exhibits some flame retardant effect, but the addition of hemicellulose oligomers and constituent sugars significantly increases the formation of carbonization. Although the exact mechanism of the synergistic relationship is unknown, it is hypothesized that the hemicellulose components help synergize the main effect, particularly carbonization, by acting as a source of active hydroxyl groups.

[0055] Furthermore, this composition acts as a binder applicable to cellulose-containing materials such as paper, cardboard, MDF, textiles, and wood, as these materials readily incorporate the composition. This property is advantageous for incorporating further compatible additives, such as smoke suppressants, which help maintain consistency within the composition and enhance its fire-delaying effect.

[0056] The present invention offers the advantage of being non-destructive, and therefore allows for the option of further purifying cellulose and even wax from lignocellulose materials for other applications.

[0057] I. Method for preparing a flame-retardant composition As disclosed herein, the inventors have surprisingly found that aqueous compositions obtained by alkali pulping of plant materials, preferably grain straw or grass, possess flame-retardant properties.

[0058] One aspect of the present invention provides a method for preparing a flame-retardant composition, the method being 1. A step of providing plant material, preferably grain straw and grasses, 2. A process of mechanically dry-treating plant material to reduce its size, 3. The process of suspending plant material in an aqueous solution, 4. A step of pulping the suspended plant material by adjusting the pH to alkaline conditions, raising the temperature of the suspension, and stirring the suspension, thereby dissolving and / or dispersing the hemicellulose and lignin components in an aqueous solution, wherein the hemicellulose and lignin components are derived from the plant material. 5. A step of separating a pulped material into a solid fiber fraction and a liquid flame retardant fraction, wherein the liquid flame retardant fraction is a flame retardant composition containing dissolved and / or dispersed hemicellulose and lignin components, 6. Optionally, the process includes a step of concentrating the liquid flame retardant composition to increase the dry matter content percentage.

[0059] Ii plant material In one embodiment, the plant material provided and used in a method for preparing a flame-retardant composition is selected from grain straw and grasses. Preferably, the plant material is grain straw. As supported in the Examples section, an efficient flame-retardant composition can be obtained from such plant material. Preferably, the grain straw material of the present invention is derived from straw, hulls and / or bran from grains and is selected from the group consisting of wheat, rye, barley, oats, sorghum, rice, triticare, and combinations thereof. In one preferred embodiment, the plant material is straw, hulls and / or bran from wheat.

[0060] In another embodiment, the present invention for preparing a flame retardant composition may be applied to lignocellulose materials derived from lignocellulose biomass, preferably non-woody biomass such as annual plants, e.g., grasses, sugarcane, palm leaves, bagasse, high-energy grasses, or other plants.

[0061] The plant material used in the present invention to prepare the flame-retardant composition is preferably non-woody biomass. As seen in Example 2, good flame-retardant properties cannot be obtained when woody biomass is used as the starting material.

[0062] In one embodiment, the grain straw material used in the method for preparing the flame retardant is a pre-treated straw material, preferably a dewaxed straw material.

[0063] Dewaxed biomass materials can be obtained by any method known in the art, such as pretreatment of lignocellulose biomass by mechanically removing wax from the surface, organic solvent extraction using chloroform, benzene, and hexane, use of supercritical CO2, or even hydrothermal treatment and wet oxidation pretreatment. Depending on the pretreatment method applied, the resulting dewaxed material may be in different forms, such as pellets, or even partially or completely suspended as a result of the previous treatment.

[0064] In one embodiment, the straw material is treated in a manner in which 50% or more of the wax is removed, for example, by treating it in a manner in which 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or even 95% or more of the total plant wax covering the surface of the plant material is removed, thereby obtaining a dewaxed straw material.

[0065] I.ii Dry mechanical processing As a first step, the plant material is mechanically dry-treated to reduce its size. In one embodiment of the present invention, this dry mechanical pretreatment of the plant material includes cutting, chopping, and / or grinding, such as mechanical treatment selected from the group consisting of shredding, hammer milling, disc milling, and combinations thereof. International Publication No. 2015 / 185688 discloses an example of dry mechanical pretreatment of plant material.

[0066] The grain straw material may be cut to lengths suitable for subsequent processing in a suitable mill for deforming the plant material. The initial cutting can result in pieces approximately 5–20 cm, 5–15 cm, or 5–10 cm in length. Milling further shreds the plant material into pieces less than 5 cm, less than 3 cm, less than 2 cm, or less than 1 cm in length.

[0067] These processes can be optimized to adjust the size according to the downstream use of the mechanically processed plant material. In one embodiment, dry mechanical pretreatment can further function to deform the outer surface of the plant material so that the wax coating is broken and released, thereby obtaining a partially dewaxed plant material.

[0068] In one embodiment, the material obtained from dry mechanical pretreatment is separated according to its dimensions. In a preferred embodiment, the dry mechanically pretreated material is subjected to a sieving process to obtain two fractions, the first fraction passing through a sieve mesh and the second fraction being held by a sieve mesh. In one embodiment of the present invention, the sieve mesh size is in the range of 0.1 to 5 mm, for example, in the range of 0.15 to 2 mm, for example, in the range of 0.2 to 0.5 mm. In a preferred embodiment, the mesh size is 0.3 mm. The sieving process may include one or more sieves having the same or different mesh sizes. The sieving process may be carried out to separate the partially dewaxed plant material (a second fraction held by the sieve) from the fraction in which the wax released by cracking is concentrated (a first fraction that passes through the sieve), and it is preferable, for example, to remove at least 65%, for example at least 75%, or for example at least 80% of the total wax in the lignocellulosic biomass by sieving.

[0069] In one embodiment, the plant material is grain straw, which is pre-treated by first performing a mechanical dry treatment, followed by fractionation. The fractionation may be performed to remove waxy components from the remaining plant material.

[0070] In another preferred embodiment, fractionation may be omitted, and the dry-mechanically pretreated material is therefore suspended directly in an aqueous solution. Following the dry treatment, the plant material (whole or selected fraction thereof) is suspended in an aqueous solution to facilitate pulping and, optionally, enzymatic treatment steps, as further disclosed herein.

[0071] In one embodiment, the plant material is grain straw, which is pretreated by first mechanical dry treatment, followed optionally by fractionation. The plant material is then suspended in an aqueous solution, and further disclosed herein, the average particle size of the plant material is less than 5 cm, less than 4 cm, less than 3 cm, less than 2 cm, or preferably less than 1 cm, in order to efficiently facilitate the pulping and optionally enzymatic treatment steps.

[0072] I.iii Enzyme-assisted dewaxing pretreatment In one embodiment of the present invention, a plant material (whole or selected fraction thereof) is enzymatically pretreated after dry mechanical pretreatment to facilitate the release and / or removal of wax from the plant material. In such embodiments, the dry mechanically pretreated material is suspended in an aqueous liquid with one or more protease and / or pectinase enzymes, and the temperature and pH are adjusted to optimize the activity of the added enzymes.

[0073] Proteases are involved in digesting long protein chains into shorter fragments by cleaving peptide bonds that link amino acid residues. In one embodiment, the protease applied in the enzymatic pretreatment may be selected from proteases that separate terminal amino acids from the protein chain (aminopeptidases, exopeptidases such as carboxypeptidase A, etc.). In another embodiment, the protease may be selected from proteases that attack the internal peptide bonds of proteins (endopeptidases such as trypsin, chymotrypsin, pepsin, papain, elastase, etc.), or from the group consisting of serine proteases, threonine proteases, cysteine ​​proteases, aspartate proteases, glutamate proteases, and metalloproteases. In yet another embodiment, the protease may be selected from commercially available proteases, for example, from the group consisting of Alcalase® (a protease derived from Bacillus licheniformis), Neutrase® (a protease derived from Bacillus amyloliquefaciens, both available from Novozymes, Denmark), and Promod® (a protease derived from Ananas comosus, available from BioCatalysts, UK). In yet another embodiment, a combination of two or more protease enzymes or commercially available protease enzyme products may be used to degrade plant proteins.

[0074] Pectinases are involved in the degradation of pectin, a polysaccharide found in plant cell walls, where, for example, cellulose fibrils are often embedded. In one embodiment, the pectinase applied to enzymatic pretreatment may be selected from the group consisting of (i) pectin hydrolases (endopolygalacturonase, EC 3.2.1.15; exopolygalacturonase, EC 3.2.1.67) that hydrolyze the pectic acid backbone in pectin, (ii) pectin lyases (endopolygalacturonase lyase, EC 4.2.2.2; exopolygalacturonase lyase, EC 4.2.2.9; endopolymethyl-d-galactosiduronate lyase, EC 4.2.2.10) that degrade pectic acid via elimination reactions, and (iii) pectin esterases (pectin methyl esterase, EC 3.1.1.11) that cleave methyl ester bonds. Pectinases are widely available commercially, and most are mixtures containing all three enzyme types described above. In another embodiment, the pectinase may be selected from the group consisting of Pectinex® (a mixture of pectinases derived from Aspergillus niger (available from Novozymes (Denmark))) and Pectinase 947L® (a range of pectinase mixtures (available from BioCatalysts, UK); and pectin-active enzyme blends (supplied by Pektozyme, DuPont)). In yet another embodiment, a combination of two or more pectinase enzymes or commercially available pectinase enzyme products may be used to break down plant pectin.

[0075] A combination of two or more proteases and / or pectinases and / or commercially available protease products and / or commercially available pectinase products may be applied to break down plant proteins and / or pectin.

[0076] In one embodiment, one or more enzymes may be added to obtain enzyme concentrations in the range of 0.01 to 2 w / w%, for example, 0.03 to 1.8 w / w%, for example, 0.05 to 1.6 w / w%, for example, 0.07 to 1.4 w / w%, or for example, 0.09 to 1.2 w / w%. The enzyme concentration depends on the enzyme activity, but an enzyme concentration of 1 to 2 w / w% may be preferred. In one embodiment, an enzyme activity in the range of 1000 to 12000 U / g may be preferred, for example, 2000 to 10000 U / g, for example, 3000 to 9000 U / g, for example, 4000 to 8000 U / g, or for example, 5000 to 7000 U / g.

[0077] To maximize the benefits of enzymatic treatment, enzyme activity conditions such as temperature, pH, and salt concentration should be optimized for the enzyme(s) used. Adding acid or base to the slurry / mixture may be necessary to achieve optimal pH conditions.

[0078] The optimal temperature during the enzymatic treatment is selected to suit the enzyme(s) used. The temperature may be 25°C, 30°C, 35°C, 40°C, 45°C, or 50°C, or even higher if heat-resistant enzymes are used. In one embodiment, the temperature of the mixture in step (d) is adjusted to a range of 30-70°C, for example, 35-65°C, for example, 40-60°C, for example, 45-55°C, preferably 45-65°C, most preferably 50-60°C, thereby optimizing the activity of the enzymes used to carry out targeted hydrolysis of cell wall components.

[0079] The optimal pH during enzymatic treatment is selected to suit the enzyme(s) used. In one embodiment, the pH maintained during enzymatic treatment is in the range of 3.5 to 7.0, for example, 4.0 to 7.0, for example, 4.0 to 6.0, preferably in the range of 4.5 to 5.5, which optimizes the activity of the enzyme used to carry out targeted hydrolysis of cell wall components. The pH can be adjusted by adding at least one acid and / or buffer selected from the group consisting of phosphoric acid, hydrochloric acid, sulfuric acid, phosphate buffer, acetate buffer, and combinations thereof. In a preferred embodiment, the acid is phosphoric acid.

[0080] To obtain optimal exposure of the biomass components to the enzyme, stirring is preferably applied, which can be selected from the group consisting of stirring and / or compressed air or gas bubbling and / or container shaking. Applicable stirrs can be selected from anchor stirrs, blade stirrs, K-stirrs, paddle stirrs, or any combination thereof.

[0081] In further embodiments, the protease and / or pectinase pretreatment of plant material further includes wet mechanical treatment during the enzymatic treatment. The wet mechanical treatment may be simultaneous with the enzymatic treatment or a subsequent mechanical treatment. For example, a selected, optimized, intermittent, time-limited, or limited wet mechanical treatment during the enzymatic treatment is preferred. In one embodiment of the present invention, the wet mechanical treatment is selected from the group consisting of a conical refiner, a disc refiner, one performed at atmospheric pressure (so-called atmospheric pressure refining), and combinations thereof, or wet milling such as a toothed colloidal mill. Such wet refining or milling may be repeated for a desired number of times. Usually, one, two, three, or four repetitions are sufficient. Alternatively or additionally, very vigorous stirring may be applied.

[0082] In preferred embodiments, the hydrolysis and wet mechanical treatment under stirring in the pretreatment is carried out for 0.5 to 5.0 hours, for example in the range of 0.5 to 4.0 hours, for example in the range of 0.5 to 3.0 hours, for example in the range of 1.0 to 2.5 hours, for example in the range of 1.0 to 2.0 hours, for example preferably in the range of 1.0 to 1.5 hours, and preferably for 1.5 hours.

[0083] As disclosed herein, protease and / or pectinase treatment facilitates the release of wax from plant material. Once the enzymatic treatment is deemed sufficient, the wax can then be removed, thereby recovering the dewaxed lignocellulose material. In one embodiment, the released wax component remains in the composition as the following steps of the method disclosed herein are carried out. In another embodiment, the wax component is partially or completely removed from the remaining dewaxed material.

[0084] In one embodiment, the dewaxed lignocellulose material can be recovered by raising the temperature of the mixture to melt and liquefy the liberated wax, and as a result, the dewaxed lignocellulose material can be separated from the liquid portion containing the molten wax. The wax can be completely or partially liquefied, depending on the composition of the wax and the temperature. When the temperature is raised to melt the liberated wax, it is desirable to reach at least a temperature at which the enzymes are inactivated. In one embodiment, the temperature of the dried mechanical and enzymatically pretreated material is raised to 65-95°C, for example in the range of 70-90°C, for example in the range of 75-85°C, for example in the range of 80-85°C, preferably to 80°C, thereby melting and liquefying the liberated wax. In one embodiment, the temperature is raised to above 70°C, preferably above 80, 90 or 95°C.

[0085] In one embodiment, wax removal and recovery of the dewaxed material are carried out by a method selected from the group consisting of decantation, centrifugation, and filtration. In principle, any known method applicable to remove the insoluble fibrous fraction from a large volume of aqueous suspension can be applied. Preferably, separation is carried out by any form of sieving / filtration using any molecular size as desired. With respect to filtration, such filtration can be selected from small mesh filters, pressure filters, belt filters, filter presses, and combinations thereof. In a preferred embodiment, pretreatment of plant material by enzyme-assisted dewaxing is performed. (a) A step of providing a plant material which is preferably grain straw, (b) A process of subjecting grain straw to dry mechanical processing, (c) The material obtained in step (b) is subjected to a sieving process to obtain at least two fractions, the first fraction passing through the sieve mesh and the second fraction being held by the sieve mesh, (d) The second fraction obtained in step (c) is suspended in an aqueous liquid together with one or more protease and / or pectinase enzymes. (e) A step in which the mixture obtained in step (d) is subjected to an optional wet mechanical treatment, (f) The step of removing wax from the solution to obtain dewaxed plant material.

[0086] I.iii Pulping treatment to solubilize hemicellulose and lignin components An essential step in this invention is pulping to solubilize the hemicellulose and lignin components. Specifically, the temperature is raised and the pH is adjusted to alkaline conditions to solubilize the hemicellulose and lignin components in solution. Such a process is traditionally called pulping, where cellulose fiber pulp is recovered. In this invention, however, there is particular interest in the liquid fraction, which the inventors have surprisingly found can be used as an efficient flame retardant.

[0087] Accordingly, in one embodiment, the present invention provides a method for providing a flame retardant composition, the method comprising the steps of obtaining a plant material disclosed herein, subjecting the plant material to a pulping treatment, and recovering a liquid fraction containing hemicellulose and lignin components for use as a flame retardant composition.

[0088] In one embodiment, the temperature in the pulping process is raised to a range of 65-120°C, for example, to a range of 65-95°C, for example, to a range of 75-85°C, for example, to a range of 80-85°C, preferably to 80°C. In one embodiment, the temperature is raised to above 65°C, preferably above 70°C, 80°C, 90°C or 95°C, more preferably above 100°C, 110°C or 120°C. In some embodiments, the pulping temperature may be even higher, above 130°C, 140°C, 150°C, 160°C, 170°C, or even up to about 180°C.

[0089] Alkaline pH conditions in the pulping process refer to a pH greater than 7. In one embodiment, the pH is 7.5, 8.0, or greater than 8.5, preferably greater than 9.0, 9.5, or 10.0, and most preferably greater than 10.5. In one embodiment, the pH is in the range of 7.0 to 12.0, for example, 8.0 to 12.0, for example, 9.0 to 12.0, preferably 10.0 to 12.0, and most preferably 10.5 to 12.0. pH adjustment to obtain alkaline conditions can be carried out by adding a base composition selected from the group consisting of sodium hydroxide, potassium hydroxide, calcium hydroxide, ammonium hydroxide, sodium carbonate, and combinations thereof. It may be preferable that the solution be stirred at such pH and temperature for 5 to 120 minutes, preferably 10 to 90 minutes, and most preferably 20 to 75 minutes.

[0090] In the most preferred embodiment, the pulping process is carried out at a temperature of about 120°C and a pH of 10.5–12.0, thereby ensuring that the hemicellulose and lignin are reliably solubilized.

[0091] In another preferred embodiment, the temperature is raised to 80–90°C and the pH to 9–11.0, thereby ensuring that hemicellulose and lignin are solubilized while the cellulose remains insoluble. This embodiment is particularly preferred when enzymatic (hemicellulase) pulping is carried out, as disclosed in the following sections. Generally, when enzymatic pulping is carried out, the pH of the pulping process is raised so as not to exceed pH 11, and the temperature is maintained below 120°C, preferably at 80–90°C.

[0092] On the other hand, if the method of the present invention is carried out without enzyme assistance for pulping (i.e., without hemicellulase treatment), the pulping process can be carried out at a high temperature of 180°C.

[0093] To obtain optimal exposure of the biomass components, stirring is preferably applied and may be selected from the group consisting of agitation and / or compressed air or gas bubbling agitation and / or container shaking. Applicable stirrs may be selected from anchor stirrs, blade stirrs, K-stirrs, paddle stirrs, or any combination thereof.

[0094] In yet another embodiment, the pulping process further includes a wet mechanical process. The wet mechanical process may be performed before and / or simultaneously with the alkali process. For example, a selected, optimized, intermittent, time-limited, or restricted wet mechanical process is preferred. In one embodiment of the present invention, the wet mechanical process is selected from the group consisting of a conical refiner, a disc refiner, one performed at atmospheric pressure (so-called atmospheric pressure refining), and combinations thereof, or wet milling such as a toothed colloidal mill. Such wet refining or milling may be repeated for a desired number of times. Usually, one, two, three, or four repetitions are sufficient. Alternatively or additionally, very vigorous stirring may be applied. As yet another alternative, the use of a screw, twin screw, or transport screw in a vessel may be a suitable method of stirring.

[0095] I.iv Enzyme-assisted pulping In one embodiment, the biomass is enzymatically treated before pulping using one or more hemicellulase enzymes suitable for breaking down hemicellulose components. The side chains of hemicellulose are interconnected with lignin in the complex lignocellulosic plant biomass structure. Breaking down hemicellulose is an essential step for separating different lignocellulosic components.

[0096] If protease and / or pectinase enzymatic treatment is performed as part of the method of the present invention, as optionally disclosed herein, the hemicellulase enzymatic treatment step may be applied (i) in combination with the protease and / or pectinase treatment described above, (ii) as a separate treatment prior to the protease and / or pectinase treatment, (iii) as a separate treatment following the protease and / or pectinase treatment, or (iii) as a separate treatment of the dewaxed lignocellulosic material after the wax has been removed.

[0097] Most preferably, the hemicellulose treatment is carried out before the pulping process, which facilitates the breakdown of hemicellulose side chains that are interconnected with lignin in the plant material.

[0098] In one embodiment, the hemicellulase enzyme applied is xylanase (EC 3.2.1.8), which randomly cleaves the internal links of the linear polysaccharide β-1,4-xylan (the main chain of most hemicellulose) to produce xylooligosaccharides of different lengths, or, if the reaction proceeds completely, xylose monomers. However, hemicellulose is not simply a linear polysaccharide of β-1,4-xylan, but also contains numerous side chains, the decomposition of which requires separate enzymatic action. Therefore, the high degree of substitution of hemicellulose polymers requires the action of various coenzymes, and thus, in another embodiment, the hemicellulase enzyme includes different glycoside hydrolases and carbohydrate esterases to completely decompose the hemicellulose substituents. In a preferred embodiment, ferulate esterase is such a coenzyme in the present invention, acting on carboxylic acid ester bonds to hydrolyze the feruloyl polysaccharide and release the ferulate. Ferulate esterase may be added to assist in the release of the lignin moiety bound to the hemicellulose.

[0099] In one embodiment, the enzyme for the decomposition of hemicellulose (hemicellulase) may be selected from the group consisting of glycoside hydrolases and / or carbohydrate esterases, for example, from the list of endoxylanase, beta-xylosidase, alpha-L-arabinofuranosidase, alpha-glucuronidase, alpha-galactosidase, acetylxylanesterase, feruloylesterase, etc. A beta-glucanase that can act on binding in amorphous cellulose within plant cell walls may be used further optionally.

[0100] Hemicellulose preparations are widely available commercially. In one embodiment, the hemicellulase may be selected from the group consisting of Depol 333P (a xylanase-rich enzyme preparation (BioCatalysts Ltd, UK)) and Depol 740L (a ferulate esterase-rich enzyme preparation (BioCatalysts Ltd, UK)). In a preferred embodiment, two or more hemicellulase enzymes or a combination of commercially available hemicellulase enzyme products may be used to decompose plant hemicellulose.

[0101] In one embodiment, one or more hemicellulase enzymes may be added to obtain enzyme concentrations in the range of 0.01 to 2 w / w%, for example, 0.03 to 1.8 w / w%, for example, 0.05 to 1.6 w / w%, for example, 0.07 to 1.4 w / w%, or for example, 0.09 to 1.2 w / w%. The enzyme concentration depends on the enzyme activity, but an enzyme concentration of 1 to 2 w / w% may be preferred.

[0102] In one embodiment of the present invention, it is preferable that the hemicellulase enzyme activity is in the range of 1000 to 12000 U / g, for example, in the range of 2000 to 10000 U / g, for example, in the range of 3000 to 9000 U / g, for example, in the range of 4000 to 8000 U / g, or for example, in the range of 5000 to 7000 U / g.

[0103] To maximize the benefits of enzymatic treatment, enzyme activity conditions such as temperature, pH, and salt concentration should be optimized for the enzyme(s) used. Adding acid or base to the slurry / mixture may be necessary to achieve optimal pH conditions.

[0104] The optimal temperature during hemicellulase treatment is selected to suit the enzyme(s) used. The temperature may be 25°C, 30°C, 35°C, 40°C, 45°C, or 50°C, or even higher if heat-resistant enzymes are used. In one embodiment, the temperature is adjusted to a range of 30-70°C, for example, 35-65°C, for example, 40-60°C, for example, 45-55°C, preferably 45-65°C, and most preferably 50-60°C, thereby optimizing the activity of the enzyme used to carry out targeted hydrolysis of cell wall components.

[0105] In yet another embodiment, the pH during hemicellulase treatment is adjusted to a range of 3.5 to 7.0, for example, 4.0 to 7.0, for example, 4.0 to 6.0, preferably 4.5 to 6.0, thereby optimizing the activity of the enzyme used to carry out targeted hydrolysis of cell wall components. The pH can be adjusted by adding at least one acid and / or buffer selected from the group consisting of phosphoric acid, hydrochloric acid, sulfuric acid, phosphate buffer, acetate buffer, and combinations thereof. In a preferred embodiment, the acid is phosphoric acid.

[0106] In preferred embodiments, the temperature and pH during hemicellulase treatment are in the range of 45-65°C and pH 4.5-6.0, respectively.

[0107] To obtain optimal exposure of the biomass components to enzymes, stirring is preferably applied, and stirring may be selected from the group consisting of agitation and / or compressed air or gas bubbling stirring and / or container shaking. Applicable stirrs may be selected from anchor stirrs, blade stirrs, K-stirrs, paddle stirrs, or any combination thereof.

[0108] In yet another embodiment, the hemicellulase treatment may include wet mechanical treatment during the enzymatic treatment. The wet mechanical treatment may occur simultaneously with the hemicellulase treatment or as a subsequent mechanical treatment. For example, a selected, optimized, intermittent, time-limited, or limited wet mechanical treatment between the hemicellulase treatments is preferred. In one embodiment of the present invention, the wet mechanical treatment is selected from the group consisting of a conical refiner, a disc refiner, one performed at atmospheric pressure (so-called atmospheric pressure refining), and combinations thereof, or wet milling such as a toothed colloidal mill. Such wet refining or milling may be repeated for a desired number of times. Usually, one, two, three, or four repetitions are sufficient. Alternatively or additionally, very vigorous stirring may be applied.

[0109] Hemicellulase treatment is considered sufficient after 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0 hours of hydrolysis, or after 6, 8, or 12 hours of hydrolysis, for example, if the desired degree of hydrolysis is obtained. In preferred embodiments, hydrolysis is carried out for 0.5 to 5.0 hours, for example in the range of 0.5 to 4.0 hours, for example in the range of 1.0 to 3.5 hours, for example in the range of 1.5 to 3.0 hours, for example preferably in the range of 1.5 to 2.5 hours, and preferably for 2 hours.

[0110] In another embodiment, the biomass may be enzymatically pretreated using one or more enzymes suitable for breaking down lignin components. Ligninases such as peroxidases and laccases may be applied in combination with any of the other enzymatic treatments described above, or as a separate step. In one embodiment, the liginase is selected from the group consisting of peroxidases and laccases.

[0111] As disclosed herein, enzymatic hemicellulose treatment and / or ligninase treatment may be carried out prior to pulping. As previously stated, if such enzymatic pulping is carried out, it is followed by alkaline extraction, but under less stringent conditions, for example, maintaining a pH of up to pH 12, preferably in the range of pH 9 to 12, and maintaining a temperature of up to 120°C, preferably in the range of 80 to 100°C.

[0112] In one embodiment of the present invention, the plant material is treated by the following steps before pulping. (a) A first enzymatic treatment of lignocellulosic biomass that has been dry mechanically treated in an aqueous suspension using one or more enzymes selected from proteases and pectinases to release wax; and

[0113] (b) A second enzymatic treatment in which cellulose is released from hemicellulose and lignin using one or more enzymes selected from hemicellulases and ligninases.

[0114] The first and second enzymatic treatments may be carried out separately or simultaneously. In one embodiment, the first enzymatic treatment is carried out on dry mechanically treated plant material, followed by the removal of free wax, and then the second enzymatic treatment is carried out on the remaining defaxed biomass.

[0115] In another embodiment, the first and second enzymatic treatments constitute a single combined enzymatic treatment step prior to pulping, and do not require wax removal.

[0116] Separation of solid fiber fraction and liquid fraction containing hemicellulose and lignin components. The material obtained after pulping is separated into a solid cellulose fiber fraction and a liquid fraction containing hemicellulose and lignin components. The liquid fraction may further contain minerals. The cellulose fiber product can be separated from the solution by any known method for separating the insoluble fraction from the bulk aqueous suspension.

[0117] In one embodiment, separation is selected from the group consisting of decantation, centrifugation, and filtration. Separation can be carried out by any form of sieving / filtration using any molecular size as desired. With respect to filtration, such filtration can be selected from small mesh filters, pressure filters, belt filters, filter presses, filter bands, and combinations thereof. Preferably, separation is carried out by a decanter centrifuge.

[0118] I.vi Concentration of liquid fraction containing hemicellulose and lignin components The liquid fraction obtained after pulping can be optionally concentrated. This may be done, for example, by evaporation. The preferred dry matter percentage of the liquid fraction obtained from the method of the present invention can vary depending on the application of the flame retardant composition. For example, for the treatment of wood strips, the preferred %DM is about 30%, while for spraying on insulation mats and fibers, the preferred %DM is about 15-20%. In one embodiment, the liquid fraction is concentrated to 2-50% DM, preferably 5-40% DM, and most preferably 10-30% DM. In one embodiment, the liquid fraction is concentrated to about 10, 15, 20, 25, 30, 35, 40, 45, or 50% DM, preferably about 20, 25, 30, 35, or 40% DM, and most preferably about 30% DM. In one embodiment, the liquid fraction is concentrated to at least 10, 15, 20, 25, or 30% DM.

[0119] As disclosed herein and evident from the experimental section, the method of the present invention for preparing a flame retardant composition comprises several optional steps. Table 1 provides a non-limiting overview of different options for carrying out the method, i.e., different options for steps to be included or omitted when preparing a flame retardant composition. [Table 1]

[0120] The "+" signifies that the process is carried out in the method.

[0121] - indicates that the step is omitted in the method.

[0122] As described above, all options listed in Table 1 may optionally be followed by a step of concentrating the liquid flame retardant fraction.

[0123] I.vii Addition of flame retardant additives In one preferred embodiment, the method further includes an additional step of adding a flame retardant additive to the liquid flame retardant composition from step (v) or a concentrated sample of the liquid flame retardant composition from step (v). The flame retardant additive further enhances the flame retardant effect of the composition.

[0124] The flame retardant additive may be selected from compounds known in the industry to have flame retardant effects, such as various inorganic and mineral compounds. Inorganic compounds may include those based on nitrogen, graphite, silica, and inorganic phosphates, such as ammonium phosphate and polyphosphate. Mineral compounds may include certain phosphates, metal oxides, hydroxides, and other metallic products, such as aluminum, zinc, and magnesium. Inorganic and mineral compounds used in conjunction with other elements can help achieve fire safety in many types of materials, including plastics, foams, textiles, and wood products. In one embodiment, the flame retardant additive is a compound based on nitrogen, graphite, silica, or inorganic phosphates, such as ammonium phosphate and polyphosphate, or a phosphate, metal oxide, hydroxide, or other metallic product, such as aluminum, zinc, and magnesium.

[0125] In one embodiment, the flame retardant additive is selected from titanium dioxide, fiberglass, mineral fibers, kaolin, talc, aluminum oxide, aluminum hydroxide, magnesium hydroxide, precipitated silica, silicates, hollow microspheres, and crushed cellulose.

[0126] Most preferably, the flame retardant additive is selected from iron oxide, calcium carbonate, and expansive graphite.

[0127] In one embodiment, the flame retardant additive is a smoke suppression compound. Examples of smoke suppressants include zinc borate, aluminum hydroxide trihydrate, zinc hydroxystanate, low melting point sulfate glass, iron oxide, zinc oxide, ferrite, bromide intercalated hydrotalcite, boric acid intercalated layered double hydroxide, hot melt adhesive compositions, functionalized graphene oxide, expandable graphene, modified ammonium poly(phosphate), glass microspheres, phosphorus-containing polyols, porous silicon dioxide PU foam, sepiolite-based nanocoatings, waste molecular sieves, melamine octamolybdate, cardanol-derived zirconium phosphate, montmorillonite nanocomposites, and waste printed circuit boards. In one preferred embodiment, the smoke suppressant is selected from calcium carbonate, iron oxide, and expandable graphite. II. Flame-retardant compositions

[0128] The flame-retardant composition of the present invention has excellent water solubility, which is advantageous with respect to its intended use, such as when applied to a surface as a liquid solution. Water solubility is particularly advantageous when treating wood, wood fibers, cellulose fibers, veneers, etc., as good penetration and distribution of the flame-retardant compound into the substrate is easily achieved in these water-absorbing, swelling matrices, and the treatment of the substrate is completed by subsequent drying. A further advantage of the flame-retardant composition of the present invention is that it is not easily washed away from the material, thereby improving the long-term benefits of flame retardancy, i.e., residual components are not easily washed away after the water evaporates.

[0129] In one embodiment, the present invention provides a flame-retardant composition comprising a lignin component and a hemicellulose component. The dry solid component in the liquid flame-retardant product of the present invention consists of a lignin component and a hemicellulose component, potentially further comprising small amounts of salt and silica, and potentially comprising some residue from cuticle wax if dewaxing is not carried out as one of the preparation steps.

[0130] In one embodiment, the present invention provides a flame retardant composition prepared by a method disclosed herein. In one embodiment, the present invention provides a flame retardant composition that can be obtained by a method disclosed herein.

[0131] The flame-retardant composition of the present invention is an aqueous composition containing hemicellulose and lignin components. Lignin-hemicellulose complexes exist in plant cell walls, where lignin subunits are bonded to hemicellulose (mainly arabinoxylan) polymer chains. Cleavage of these bonds (ester and ether forms) breaks them, releasing lignin and hemicellulose fragments from the complex. Process conditions applied during the preparation of the flame retardant can lead to the destruction of such ester bonds between hemicellulose and lignin in the plant material, as well as bonds within the hemicellulose itself. Depending on the applied temperature and pH, even ether bonds in the lignin, and even ether bonds between lignin and hemicellulose, can be affected.

[0132] Therefore, plant lignin and hemicellulose are broken down into lignin and hemicellulose components by the method for preparing the flame retardant composition. More specifically, the degree of polymerization of hemicellulose is reduced due to alkaline pulping conditions and enzymatic treatment; for example, arabinoxylan is broken down into oligosaccharides with a degree of polymerization (DP) ranging from 2 to 20 based on cleavage of the xylan backbone, and a small amount of soluble, more highly polymerized arabinoxylan fragments (>20DP) may also be present. Plant lignin is broken down into fragments with molecular weights generally ranging from 500 to 9000 daltons. Methods for measuring / identifying these hemicellulose and lignin components are disclosed in Section IV. The hemicellulose and lignin components are dissolved and / or dispersed in aqueous solutions, and therefore the flame retardant composition of the present invention has excellent water solubility.

[0133] As described above, the main components of the flame-retardant composition of the present invention are a lignin component and a hemicellulose component. In one embodiment, the flame-retardant composition contains at least 60%, 70%, 80%, or 90% of the hemicellulose component and lignin component based on the total dry matter content.

[0134] Other extracts and decomposition products, such as acetic acid from the decomposition of hemicellulose, may also be present in the composition. The amount of such other extracts may vary, but based on the total dry solids, they typically constitute about 2–5% of the composition. Furthermore, grain straw and grass contain silicates that can react with alkali to form salts such as sodium or potassium salts, and therefore, these may also be included in the composition. Such silicates can be beneficial in flame-retardant formulations because they form a protective layer, promote carbonization, undergo endothermic reactions, and have the ability to suppress smoke. These contributions enhance the overall fire resistance of the material and contribute to safer fire management. Finally, residual NaOH or KOH from alkali pulping may constitute about 1–5%, depending on the initial concentration and pulping conditions applied.

[0135] In one embodiment, the ratio of lignin to hemicellulose components in the flame retardant composition (L:H ratio, based on dry material weight (DM), (w / w)) is 80:20 to 20:80, 75:25 to 25:75, 70:30 to 30:70, 65:35 to 35:65, 60:40 to 40:60, 55:45 to 45:55, or even 50:50. In a preferred embodiment, the ratio of lignin to hemicellulose components in the flame retardant composition is 60:40 to 40:60.

[0136] In one embodiment, the total dry matter content of the flame retardant composition consists essentially of lignin and hemicellulose components. In one embodiment, the flame retardant composition contains 20-80% DM dissolved and / or dispersed lignin and 20-80% DM dissolved and / or dispersed hemicellulose components. In one embodiment, the flame retardant composition contains 30-70% DM dissolved and / or dispersed lignin and 30-70% DM dissolved and / or dispersed hemicellulose components. In one preferred embodiment, the flame retardant composition contains 40-60% DM dissolved and / or dispersed lignin and 40-60% DM dissolved and / or dispersed hemicellulose components. In one embodiment, the flame retardant composition contains approximately 50% DM dissolved and / or dispersed lignin and approximately 50% DM dissolved and / or dispersed hemicellulose components.

[0137] In further embodiments, the flame retardant composition includes other components in addition to the lignin and hemicellulose components. Thus, in such embodiments, the lignin and hemicellulose components may constitute at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95% (based on total dry matter content) of the flame retardant composition, where the ratio of lignin to hemicellulose components is as disclosed above. These other components may be selected from calcium carbonate and / or iron oxide. In one embodiment, the flame retardant composition contains 0.1–2% calcium carbonate and / or 0.1–2% iron oxide (percentages are based on total dry matter content). These components, along with other additives such as TiO2 or expansive graphite, as well as diatomaceous earth, can provide thermal insulation, improve the operability of the carbon layer during flame, suppress smoke, and / or other synergistic functions. The inclusion of these compounds in the flame retardant composition enhances the effectiveness of the composition as a flame retardant. The final combined flame-retardant composition (i.e., comprising a liquid flame-retardant fraction obtainable by the method disclosed herein and one or more additional components disclosed herein) acts as a binder, resulting in high flame retardancy and thermal insulation properties when applied to, for example, woody materials.

[0138] In one preferred embodiment, the flame retardant composition comprises a flame retardant additive disclosed herein. The flame retardant additive further enhances the flame retardant effect of the composition. In one embodiment, the flame retardant additive is a smoke suppression compound. In one preferred embodiment, the flame retardant additive is selected from calcium carbonate, iron oxide, and expansive graphite. In one embodiment, the present invention provides an aqueous composition for use as a flame retardant, comprising dissolved and / or dispersed hemicellulose and lignin components, which can be obtained by the method disclosed herein. Specifically, the aqueous composition comprises dissolved and / or dispersed hemicellulose and lignin components in the proportions and amounts disclosed above. III. Potential Applications of Flame Retardant Compositions

[0139] The liquid compositions containing lignin and hemicellulose components, produced from the pulping processes disclosed herein, are highly effective flame retardants for wood products when applied by immersion. Another means of applying the flame retardant compositions is pressurized and / or vacuum impregnation, such as those commonly used in the wood industry. Yet another means of applying the flame retardant compositions is by spraying onto fibers, followed optionally by flash drying.

[0140] Due to its excellent water solubility, the flame-retardant composition of the present invention is particularly useful in applications to wood and cellulose / lignocellulose products such as fibers, fiber mats, veneers, and wood-based composites, as well as solid wood products.

[0141] In one embodiment, the flame-retardant composition is applied to solid wood elements, wood composites and their wood elements, or insulation materials based on wood fibers and other natural fibers such as cotton, flax, hemp, sisal, and jute (e.g., loose fiberfill, preformed panels, and bats) for use in furniture, building products, etc. One example of use is in fiber cement board, where the fibers (e.g., cellulose fibers or synthetic fibers) may be impregnated before being incorporated into the board.

[0142] In one embodiment, the present invention relates to using a liquid composition, which can be obtained by the methods disclosed herein, as a flame retardant, for example, by applying the composition to the surface of an article, immersing an article in the composition, and / or impregnating an article with the composition.

[0143] In one embodiment, the present invention provides a method for improving the fire resistance of an article by applying a liquid composition, which can be obtained by the method disclosed herein, to the article, for example, by applying the composition to the surface of the article, immersing the article in the composition, and / or impregnating the article with the composition.

[0144] In one embodiment, the present invention provides a method for improving the fire resistance of an article by treating the article with a liquid composition that can be obtained by the method disclosed herein, compared to an untreated sample, for example by applying the composition to the surface of the article, immersing the article in the composition, and / or impregnating the article with the composition.

[0145] In one embodiment, the present invention provides cellulosic or lignocellulosic products comprising a liquid flame retardant composition that can be obtained by the methods disclosed herein, such as products selected from solid wood elements, wood composites, paper, corrugated cardboard, MDF, wood fibers and / or other natural fibers (e.g., cotton, flax, hemp, sisal, jute), and textile products.

[0146] IV. Methods for analyzing and / or characterizing flame-retardant compositions Methods for characterizing flame-retardant compositions, specifically for identifying the amounts and structures of lignin and hemicellulose components, are provided herein.

[0147] II.i Lignin Content The lignin content can be determined as follows: Lignin is precipitated from the flame retardant composition by gradually lowering the pH to 4.5 using sulfuric acid. The lignin-enriched precipitate is then isolated by filtration using a fine nylon cloth, then washed with fresh acidified water (pH 4.5), and subsequently dried in an oven at 65°C and weighed. The mass of the dried lignin precipitate is obtained as the lignin content of the material and is proportional to the initial dried solids content and volume treated. The lignin fraction can then be further characterized by HPLC analysis and analysis of the resulting fragments as oxidation products after nitrobenzene oxidation of the dried material. This provides information such as the G:S:H ratio of aromatic component units in the lignin (G = guaiacyl, S = syringyl, and H = p-hydroxyphenylphenylpropanoid).

[0148] II. Hemicellulose content The hemicellulose content can be determined as follows: The residual solution from which lignin has precipitated is analyzed by HPLC and used in particular to identify and quantify the sugar composition of the hemicellulose component, i.e., to identify different hemicellulose oligomers.

[0149] A portion (for example, 25 mL of a typical 32% concentrate) is mixed with concentrated sulfuric acid to reach an acid concentration of 72-74% H2SO4. The mixture is heated to 120°C (in an autoclave) for 20 minutes, cooled, and water is added to reach a final H2SO4 content of 4%. The subsequent liquid is then filtered through a fine nylon mesh cloth, and 25 mL is neutralized by dropwise addition of NaOH (50% solution). The neutralized liquid is then directly introduced into a suitable HPLC configuration for sugar analysis. For example, a Waters system using a Shodex SP 0810 column, isocratic with water as the eluent (flow rate 0.5 mL / min), using a differential refractometer as the detector, and using a suitable monosaccharide sugar standard for calibration.

[0150] Residual ash and salt content

[0151] Residual ash and salt content are determined on a dry sample of the material by heating / ashing at 600°C for 12 hours using a muffle furnace. The residual mass is used to determine the ash content.

[0152] II. iv. Wax content The total wax content of plant material can be determined by gravimetric method as the total extractable lipophilic compounds. The dried plant material is crushed and extracted with hot / boiling chloroform. This is carried out by one of two basic methods, with method 2 being preferred over method 1 when the bulk density of the plant material is high. 1. A precisely weighed portion of pulverized biomass (oven-dried) is placed in a Soxhlet chimble and subjected to 12 hours of extraction in a Soxhlet extraction system using the standard Soxhlet method. After extraction, the chimble and remaining solid material are dried at 103°C, and the extracted wax is determined by the mass difference compared to the starting material. 2. Approximately 30 g (accurately weighed) of dried and crushed straw or other plant material is placed in a 2 L round-bottom flask, to which 1 L of chloroform is added. The flask is fitted with a reflux condenser, and the material is refluxed in chloroform for at least 3 hours. After this time, the remaining solid is quantitatively collected, then dried (103°C) and weighed. The wax content is determined by the mass difference relative to the input material.

[0153] II.v Properties of Liquid Flame Retardant Compositions The flame-retardant composition of the present invention is characterized by the proportion of lignin-derived material (i.e., lignin component) and hemicellulose-derived material (i.e., hemicellulose component), and the internal chemical species.

[0154] Straw hemicellulose is primarily arabinoxylan, and the arabinose-to-xylose ratio in this hemicellulose is well known. The hemicellulose components (oligomers and possibly longer polymers) in flame retardant compositions will directly reflect this. By HPLC analysis, the constituent sugars of hemicellulose can be identified and measured. Based on this, the hemicellulose source can be identified. Specifically, for arabinoxylan, the amount and ratio of arabinose to xylose is 1:4. By ion chromatography (DIONEX) and PAD detection, oligosaccharides with approximately 1–20 DP can be separated and detected. Furthermore, by size exclusion chromatography and / or mass spectrometry, oligo / polysaccharides can be separated and their mass distribution profiles can be determined.

[0155] Lignin in grain straw differs significantly from that in coniferous trees. Grain straw lignin contains monomethoxylated (guaiacyl (G)), dimethoxylated (syringyl (S)), and non-methoxylated (p-hydroxyphenyl (H)) phenylpropanoids, while coniferous tree lignin mainly contains guaiacyl and 4-hydroxyphenylpropane residues. These compounds can be detected by HPLC analysis of the lignin component in flame retardant compositions. Specifically, for grain straw lignin, the G:S:H ratio (G=guaiacyl, S=syringyl, and H=p-hydroxyphenylphenylpropanoid) is approximately 45:45:10 (based on %DM).

[0156] Preferred Embodiments of the Invention Preferred Embodiment 1. A method for preparing a flame retardant composition containing hemicellulose and lignin components from plant material, (i) A step of providing plant material, Here, the plant material is selected from grain straw and grass, and the process of providing it is as follows: (ii) A process of mechanically dry-treating plant material in order to reduce its size, (iii) A step of suspending the plant material in an aqueous solution, (iv) A step of adjusting the pH to alkaline conditions, raising the temperature of the suspension, and stirring the suspension, thereby dissolving and / or dispersing the hemicellulose and lignin components in the aqueous solution, wherein the hemicellulose and lignin components are derived from plant material. (v)(iv) A step of separating the material obtained in step (v)(iv) into a solid fiber fraction and a liquid flame retardant fraction, wherein the liquid flame retardant fraction is a flame retardant composition containing dissolved and / or dispersed hemicellulose and lignin components, (vi) A method comprising the optional step of concentrating a liquid flame retardant composition to increase the dry matter content percentage.

[0157] Preferred Embodiment 2. The method according to Preferred Embodiment 1, wherein the temperature in step (iv) is raised to over 80°C and the pH is 9-12.

[0158] Preferred Embodiment 3. The method according to Preferred Embodiment 1 or 2, wherein the average particle size of the plant material in step (iii) is less than 1 cm.

[0159] Preferred Embodiment 4. The method according to any one of the preferred embodiments 1 to 3, wherein the suspended plant material in step (iii) is enzymatically treated with one or more hemicellulase enzymes such as xylanase and / or ferulate esterase.

[0160] Preferred Embodiment 5. The method according to any one of Preferred Embodiments 1 to 4, wherein the ratio of hemicellulose component to lignin component in the flame retardant composition is 40:60 to 60:40 based on dry matter content.

[0161] Preferred Embodiment 6. The method according to any one of Preferred Embodiments 1 to 5, wherein the flame retardant composition comprises at least 90% hemicellulose and lignin components based on total dry matter content. Preferred Embodiment 7. The plant material suspended in the aqueous solution in step (iii) is dewaxed grain straw, for example, (a) A step of enzymatically treating the grain straw suspended in the aqueous solution in step (iii) with a protease and / or pectinase enzyme, (b) The mixture obtained in step (a) is optionally subjected to a wet mechanical treatment, The method according to any one of the preferred embodiments 1 to 6, wherein the dewaxed grain straw is obtained by a method comprising the step of removing wax from the solution before adjusting the pH and raising the temperature in step (v).

[0162] Preferred Embodiment 8. A flame retardant composition that can be obtained by the method of any one of Preferred Embodiments 1 to 7, wherein the composition comprises dissolved and / or dispersed hemicellulose and lignin components in a ratio of 40:60 to 60:40 based on dry matter content.

[0163] Preferred Embodiment 9. The flame retardant composition according to Preferred Embodiment 8, wherein the hemicellulose component comprises a monomer, oligomer, and / or polymer of arabinoxylan, and the lignin component comprises monomethoxylated (guaiacyl(G)), dimethoxylated (syringyl(S)), and nonmethoxylated (p-hydroxyphenyl(H)) phenylpropanoids.

[0164] Preferred Embodiment 10. Use as a flame retardant of an aqueous composition containing dissolved and / or dispersed hemicellulose and lignin components, which can be obtained by the method described in any one of Preferred Embodiments 1 to 7.

[0165] Preferred Embodiment 11. Use of an aqueous composition comprising dissolved and / or dispersed hemicellulose and lignin components, which can be obtained by the method of any one of Preferred Embodiments 1 to 7, to improve the fire resistance of articles, such as solid wood elements, wood composites, and / or wood fibers, and other natural fibers such as cotton, flax, hemp, sisal, and jute, which are insulating materials.

[0166] Preferred Embodiment 12. The use according to Preferred Embodiment 10 or 11, wherein the ratio of hemicellulose component to lignin component in the aqueous composition is 40:60 to 60:40 based on dry matter content.

[0167] Preferred Embodiment 13: Use according to Preferred Embodiments 10-12, wherein the hemicellulose component comprises a monomer, oligomer, and / or polymer of arabinoxylan, and the lignin component comprises monomethoxylated (guaiacyl(G)), dimethoxylated (syringyl(S)), and nonmethoxylated (p-hydroxyphenyl(H)) phenylpropanoids.

[0168] Preferred Embodiment 14: The use according to preferred embodiments 10 to 13, wherein the hemicellulose and lignin components constitute at least 90% of the total dry matter content of the aqueous composition.

[0169] Preferred Embodiment 15. The use according to Preferred Embodiments 10-14, wherein the aqueous composition is applied to an article by impregnating the article with the composition, such as by spraying the composition onto the surface of the article, immersing the article in the composition, and / or by vacuum pressure impregnation.

[0170] Preferred Embodiment 16. A method for improving the fire resistance of an article, comprising applying to the article a flame-retardant composition comprising dissolved and / or dispersed hemicellulose and lignin components, which can be obtained by the method described in any one of Preferred Embodiments 1 to 8.

[0171] Preferred Embodiment 17: The method according to Preferred Embodiment 16, wherein the ratio of hemicellulose component to lignin component in the aqueous composition is 40:60 to 60:40 based on dry matter content.

[0172] Preferred Embodiment 18. The method according to Preferred Embodiment 16 or 17, wherein the hemicellulose component comprises a monomer, oligomer, and / or polymer of arabinoxylan, and the lignin component comprises monomethoxylated (guaiacyl(G)), dimethoxylated (syringyl(S)), and nonmethoxylated (p-hydroxyphenyl(H)) phenylpropanoids.

[0173] Examples Example 1A: Lignin-based flame retardant - Initial test 1A.1 Sample Preparation Mechanical dry processing and fractionation: Wheat straw was mechanically processed dry by hammer milling. The hammer-milled straw was fractionated using an 8 mm sieve. The fraction passing through the sieve was then processed in a dust separator to remove fine material (15-20% of the straw mass was removed as fine material). Next, the long fraction resulting after the removal of fine material was further dedusted by gentle disc milling (1 mm plate gap in the disc mill), and an additional approximately 5% of the dust fraction was removed using a 0.3 mm sieve. The long fraction now consisted mainly of straw pieces 2-3 mm in length.

[0174] Protease and pectinase treatment: This long fraction was suspended in 55°C water in a jacketed steel tank with a load of 85 kg per 1400 L / water (equivalent to approximately 75 kg of dry straw). The pH of the resulting slurry was adjusted to pH 5.3 using phosphoric acid, and the temperature was maintained at approximately 55°C. The slurry was stirred using a Myers-type dispersion mixer to ensure good dispersion. 200 mL of protease-rich preparation (Promod 24 L, BioCatalysts Ltd, UK) and 100 mL of pectinase-rich yeast preparation (Pectinase 974 L, BioCatalysts Ltd, UK) were added to break down the straw cuticle and aid in the release of the constituent wax. The slurry was circulated through a Fryma-type wet mill equipped with a toothed colloidal mill head, with a wide mill head gap (>2 mm), meaning the mill acted more as an effective pump mixer than a true grinding mill, helping the enzymes to reliably access the straw cuticle surface. Wet milling and stirring were applied during the enzymatic treatment while maintaining the pH and temperature profiles identified above. After 1 hour, the slurry temperature was raised to 80°C to ensure all wax components were in a molten state, and the mixture was stirred for a further 10 minutes. Next, a decanter centrifuge using a GEA UCD 2015 two-phase decanter was operated at a slurry feed rate of 1800 L / hour and a barrel speed of 5500 rpm to separate the insoluble fibrous fraction from the bulk process liquid. This product is called the dewaxed material.

[0175] Hemicellulase treatment: For hemicellulose treatment, the temperature was raised to 55°C and the pH was adjusted to 5.3 using phosphoric acid. A xylanase-rich enzyme preparation (primarily endoxylanase activity; Depol 333P, BioCatalysts Ltd, UK) and a ferulate esterase-rich enzyme preparation (Depol 740L, BioCatalysts Ltd, UK) were added. Enzymatic hydrolysis was carried out for 2 hours with mechanical stirring, while maintaining the pH and temperature profiles specified above. The straw was continuously refined during enzymatic hydrolysis by circulating it through a Fryma-type toothed colloidal wet mill with a head gap of 1.5 mm (to a degree sufficient to vigorously stir the mixture).

[0176] Alkaline pulping treatment: Enzymatic hydrolysis was terminated by raising the pH to 11 by adding NaOH and raising the temperature to 80°C. Stirring was continued for a further 90 minutes. This dissolved the released lignin and hemicellulose fragments.

[0177] Decanter centrifugation using a GEA UCD 205 two-phase decanter was performed, operating at a speed of 5500 rpm with a slurry flow rate of 1800 L / hour, to separate the insoluble fibers from the aqueous liquid phase.

[0178] Concentration by evaporation: The aqueous liquid phase (with a dry solids content of approximately 4-5%) containing the dissolved and dispersed lignin and hemicellulose fragments was then concentrated by evaporation to a dry solids content of 30% for sample (a), 15% for sample (b), or 7.5% for sample (c).

[0179] 1A.2 Flame Retardancy Test - Beech Wood Strip Test Samples (a), (b), and (c) obtained as disclosed above were tested for their flame retardant properties as follows: Beech wood strips (200 mm long, approximately 20 mm wide, single-layer strips, approximately 1.5 mm thick) were immersed in the sample and left for 20 minutes to allow them to permeate the sample. After that, the liquid was drained and the strips were dried in a 70°C oven for 45 minutes.

[0180] Next, an attempt was made to ignite the treated strip using a cigarette lighter or a candle lighter. The results were as follows:

[0181] Sample (a): Dry solids content 30%. The flame hardly spread, and any small flames that did appear extinguished approximately 1 cm above the strip. See Figure 1. Sample (b): Dry solids content concentration 15%. Same flame suppression effect as sample (a). See Figure 1. Sample (c): Dry solids content concentration 7.5%. Same flame suppression effect as sample (a). See Figure 1.

[0182] For control, untreated beech wood strips were also tested. This untreated wood burned freely until the strips were consumed.

[0183] Example 1B: Lignin-based flame retardant - Additional test All samples tested in Example 1 were treated in the same manner by dry mechanical treatment, fractionation, protease and pectinase treatment, hemicellulose treatment, and alkali pulping treatment, with the only difference being the concentration step (i.e., final %DM). This example demonstrates that good flame retardant products can be obtained from plant materials by simplifying the method, i.e., only dry mechanical treatment (size reduction) and alkali treatment are essential steps in this method.

[0184] 1B.1 Sample Preparation Sample 1 was prepared by a combination of dry mechanical processing, fractionation, and alkaline pulping of straw. 1. Mechanical dry processing of straw: Wheat straw was mechanically processed dry by hammer milling. 2. Separation: The hammer-milled straw was separated using an 8mm sieve. The fraction passing through the sieve was then processed in a dust separator to remove fine particles (15-20% of the straw mass was removed as fine particles). The long fraction that remained after the removal of the fine particles was then further de-dusted by gentle disc milling (1mm plate gap in the disc mill), and an additional approximately 5% of the dust fraction was removed using a 0.3mm sieve. The long fraction now consisted mainly of straw pieces 2-3mm in length. 3. Aqueous suspension: This long fraction was suspended in 55°C water in a jacketed steel tank at a load of 85 kg per 1400 L of water (equivalent to approximately 75 kg of dry straw). 4. Alkaline pulping treatment of straw: The pH in the tank was raised to 11 by adding NaOH, and the temperature was raised to 80°C. Stirring under these conditions was carried out for 120 minutes. This released an alkaline mixture of lignin and hemicellulose from the straw substrate, and dissolved the lignin and hemicellulose fragments. 5. By decanter centrifugation using a GEA UCD 205 two-phase decanter, the slurry was operated at a speed of 5500 rpm at a rate of 1800 L / hour to separate the insoluble fibers from the aqueous liquid phase. The aqueous liquid phase, containing dissolved and dispersed lignin and hemicellulose fragments (with a dry solids content of approximately 4-5%), was then optionally concentrated by evaporation to a dry solids content of 32%.

[0185] Sample 2 was prepared by a combination of dry mechanical processing and alkaline pulping of straw. 1. Mechanical dry processing of straw: Wheat straw was mechanically processed dry by hammer milling. 2. Aqueous suspension: The hammer-milled straw was suspended in 80°C water in a jacketed steel tank at a rate of 85 kg per 1400 L of water (equivalent to approximately 75 kg of dry straw). 3. Alkaline pulping treatment of straw: The pH in the tank was raised to 11 by adding NaOH, and the temperature was maintained at 80°C. Stirring under these conditions was carried out for 120 minutes. This released an alkaline mixture of lignin and hemicellulose from the straw substrate, and dissolved the lignin and hemicellulose fragments. 4. Using a GEA UCD 205 two-phase decanter, the slurry was separated from the aqueous liquid phase by decanter centrifugation at a rate of 5500 rpm, with a flow rate of 1800 L / hour. The aqueous liquid phase, containing dissolved and dispersed lignin and hemicellulose fragments (approximately 4-5% dry solids content), was then optionally concentrated by evaporation to a dry solids content of 32%.

[0186] Sample 3 was prepared by a combination of dry mechanical processing, fractionation, and alkaline pulping of straw. 1. Mechanical dry processing of straw: Wheat straw was mechanically processed dry by hammer milling.

[0187] 2. Removal of "dust": Dust particles smaller than 0.2 mm were removed. 3. Aqueous suspension: The remaining 109g of straw was suspended in 2L of water (solid content approximately 5%). 4. Alkali pulping treatment: The pH was adjusted to 10.5 using a 27% NaOH solution. The temperature was raised to 95°C, and the mixture was stirred at this temperature for 2 hours, with milling every 20 minutes. Throughout the entire reaction time, the pH was maintained between 10 and 10.5. 5. The liquid phase was separated from the fibers by filtration using a filter bag with a mesh size of 125 microns. The liquid phase was then concentrated to a dissolved solids content of 35.8% by rotary evaporation.

[0188] Sample 4 was prepared by a combination of dry mechanical processing, fractionation, and alkaline pulping (at a higher pH) of straw. 1. Mechanical dry processing of straw: Wheat straw was mechanically processed dry by hammer milling. 2. Removal of "dust": Dust particles smaller than 0.2 mm were removed. 3. Aqueous suspension: The remaining 109g of straw was suspended in 2L of water (solid content approximately 5%). 4. Alkali pulping treatment: The pH was adjusted to 12.5 using a 27% NaOH solution. The temperature was raised to 95°C, and the mixture was stirred at this temperature for 2 hours, with milling every 20 minutes. Throughout the entire reaction time, the pH was maintained between 12 and 12.5. 5. The liquid phase was separated from the fibers by filtration using a filter bag with a mesh size of 125 microns. The liquid phase was then concentrated to a dissolved solids content of 30% by rotary evaporation.

[0189] Sample 5 was prepared by a combination of dry mechanical processing, fractionation, and alkaline pulping (at a higher pH) of wood fibers. 1. Wood fiber, TMP type (i.e., non-deligninized). 2. Aqueous suspension: 113 g of wood fiber was mixed with 3 L of water, and the temperature was raised to 95°C. The pH was raised to 11 using a 27% NaOH solution. This mix was stirred at this temperature for 2 hours, with milling every 20 minutes. The pH was maintained between 10.5 and 11 during the extraction period. 3. The liquid phase was separated from the fibers by filtration using a filter bag with a mesh size of 125 microns. The liquid phase was then concentrated to a dissolved solids content of 30% by rotary evaporation.

[0190] 1B.1 Flame Retardancy Test - Beech Wood Strip Test The samples obtained as disclosed above were tested for their flame retardant properties as follows.

[0191] Each liquid phase was used separately to treat a wooden sample (beech wood stick - "tongue depressor") measuring 115 mm x 20 mm x 1.5 mm thick. Half the length of the stick was immersed in the corresponding solution for 15 minutes, after which excess liquid was wiped off with tissue paper, and the treated stick was dried in an 80°C oven for 30 minutes.

[0192] The treated sticks were then tested by applying the flame of a candle lighter from a distance of 2 cm for 15 seconds to the underside of the stick, 1 cm from the end. result: Samples 1-4 barely ignited and burned for a maximum of 2 seconds until charring formed and the flames extinguished. Sample 5 (wood fiber extract) ignited and burned for over 20 seconds until charring occurred and the flames extinguished, burning at least 8 cm along the stick during that time. This indicates that liquids derived from pulped straw are efficient flame retardants, while liquids derived from pulped wood fibers are not ideal as flame retardants.

[0193] Example 2: Thermal insulation material Furthermore, wood fibers manufactured for thermal insulation were treated, as were wood fiber insulation mats similar to rock wool mats but using wood fibers instead, which were treated with the flame retardant product of the present invention.

[0194] Specifically, pre-formed insulation mat sections (65 mm × 60 mm × 400 mm) were immersed overnight in the 32% dissolved solids flame retardant composition of the present invention (prepared as disclosed in Example 1), then drained, and subsequently dried at 75°C for 12 hours. In such applications, it was found to function very well as a flame retardant.

[0195] Example 3: Effects of Oxidation In a further experimental setup, the flame-retardant composition (prepared as disclosed in Example 1) was oxidized with hydrogen peroxide. Theoretically, the sample would thus more closely resemble the “oxidation product” and therefore better carbonize and suppress flames.

[0196] Specifically, the composition was oxidized at 80°C, with 100 ml of 35% hydrogen peroxide applied per 2 L of flame retardant composition, at a pH of 10.5, a temperature of 80°C, and an incubation time of 2 hours.

[0197] This oxidized composition was applied to wood strips in the same manner as described above (beech wood strip test) in both 30% and 15% dry solids preparations. In both cases, the flame retardant effect described above was observed - see Figure 2. Therefore, oxidation can be an option and beneficial (see also Example 6 below).

[0198] Impregnating wood samples in the flame-retardant composition has been shown to be a sufficient method for achieving the best results, namely improved thermal stability, increased charring, self-extinguishing properties, and reduced smoke generation, thereby confirming that this composition is a good flame retardant.

[0199] Example 4: Comparison with commercially available water-based flame retardant formulations Phosphoric acid is a known flame inhibitor (phosphate). Wood strips were treated with phosphoric acid alone. This treatment was found to be only slightly more flame-retardant compared to the control (untreated wood strip), but it burned slowly. On the other hand, when phosphoric acid (about 1% w / v) was added to the flame-retardant composition of the present invention, and wood strip tests were performed using both 30% and 15% dry solids lignin formulations, the flame inevitably extinguished after burning perhaps 1 cm along the strip. Thus, the effect was the same as sample (a) above, but with no particular further improvement.

[0200] Commercial flame retardant formulations containing admixtures of diammonium phosphate and ammonium dihydrogen phosphate were tested and compared with the flame retardant composition of the present invention (prepared as disclosed in Example 1). The flame retardant composition of the present invention was found to perform best.

[0201] Example 5: Combined effect of lignin and hemicellulose fragments in wood strip tests 5.1 Composition analysis The flame retardant product of the present invention prepared in Example 1 is a mixture of lignin and hemicellulose oligomers extracted from straw after alkali treatment. The hemicellulose and lignin content was determined as described in Section IV, and it was found that the dry solids in the mix consisted of approximately 60-65% lignin-derived material, with the remainder being oligosaccharide fragments of hemicellulose (mainly arabinoxylan type).

[0202] 5.2 The mixture is superior to the use of lignin and hemicellulose fragments individually. The lignin fraction of the flame retardant composition was precipitated, resuspended in water with a dry solids content of 32%, and tested for flame retardancy using birch veneer wood strips as disclosed herein. Some inhibition was observed, but it was inferior to that of the “mixed” flame retardant composition (i.e., a composition containing lignin and hemicellulose components).

[0203] Furthermore, the isolated "hemicellulose-enriched" fraction described above was also used to treat wood strips in the same manner. No signs of flame retardancy were observed in this case.

[0204] Therefore, it can be concluded that in order for the composition to have good flame retardant properties, both hemicellulose and lignin components should be present, preferably in proportions close to the original mix.

[0205] Example 6: Additional carbonization formation studies Studies have been conducted to show that the flame retardant product of the present invention generates a large amount of carbonization compared to lignin alone (i.e., lignin derived from the flame retardant composition of the present invention and isolated as a "pure" component).

[0206] TGA / DSC analysis (in nitrogen) is performed at 50-800°C for 10°C min. -1The analysis was performed using an Al2O3 crucible at a heating rate of 1 / 2 in a METTLER TOLEDO TGA / DSC 1 STARe System instrument. The samples analyzed were pure lignin samples, mixed samples of hemicellulose and lignin (i.e., the flame retardant compositions of the present invention), and oxidized mixed samples of hemicellulose and lignin (i.e., the oxidized flame retardant compositions of the present invention). Approximately 15 mg of each sample was weighed before analysis.

[0207] Data analysis was performed via STARe software. The main results extracted from the data were (i) residual mass and its corresponding percentage, and (ii) onset temperature, which is the temperature at which the sample begins to decompose. This is defined as a 2% weight loss (minus the weight of water).

[0208] The results of the TGA trial are summarized in Table 2. [Table 2]

[0209] Thermal testing (TGA) showed that this “mixture” left approximately 53% of its mass after heating to 800°C, while “purified” lignin from the same material left only 45% (consistent with other observations regarding lignin in general). Furthermore, when the “mix” (i.e., a mix / admixture of lignin and hemicellar materials) was oxidized, the residue after heating to 800°C increased again to 60%. This suggests that better flame retardant behavior (at least based on “carbonization” or “carbonization-promoting” ability) is exhibited by the “mix” product (i.e., flame retardant compositions obtained from straw pulping) and its oxidized version, rather than by purified lignin.

[0210] Example 7: Smoke suppression As a further step, it was observed that although the flames were demonstrably suppressed by the flame-retardant composition of the present invention applied to wood and wood fibers, some persistent smoke was still observed even after the flames had subsided. To address this, calcium carbonate and iron oxide were added to the flame-retardant composition at levels of 1-3%, resulting in an effective reduction, or almost complete elimination, of this smoke.

[0211] Example 8: Fire test of scaled-up wood treatment The Mini-SBI test was conducted at the DBI-Dansk Brand- og sikringsteknisk Institut (Danish Fire and Security Institute). The Mini-SBI is a geometrically scaled version of the SBI test (EN13823), which is the primary fire test for classifying building materials in Europe. SBI test = Single Combustion Test Geometrically, the sample for the Mini-SBI is scaled by a factor of 6.25 from the original SBI and is symmetrical on both sides. The sample size is 200 mm wide x 600 mm high, with a maximum thickness of 50 mm. Two plates are required to assemble a corner / 90-degree angle / L-shaped configuration.

[0212] This device measures the heat release rate (HRR) using oxygen consumption calorimetry, which is the same method used in the SBI test. Based on these measurements, S-THR (scale value of total heat release) and S-FIGRA (scale value of Fire Gowth Rate) can be determined. Samples: The following samples were tested using a mini-SBI instrument. - Scots pine wood treated with the flame-retardant liquid composition prepared according to Example 1, sample (a) (tests 414 and 415) - Untreated Scotts pine wood (negative control, test 417)

[0213] The treated samples were impregnated. Processing parameters: 0.1 bar for 60 minutes, then 13 bar for 120 minutes; dry pre-vacuum.

[0214] Heat Ratio (HRR): The heat ratio is the amount of energy released as a function of time by a burning object, given in kW. This energy ratio is measured using oxygen consumption calorimetry via a gas measuring instrument in the apparatus. The performance of a sample is determined by the amount and rate of energy released. Therefore, good performance is achieved by a sample that releases a small amount of energy over a long period of time, thereby delaying combustion.

[0215] As shown in Figure 3A, the sample treated with the flame-retardant composition of the present invention showed better performance compared to the untreated sample by releasing a small amount of energy.

[0216] Total Heating Rate (THR): The total heating rate is the cumulative energy released by the sample during the test, and is given in MJ.

[0217] As shown in Figure 3B, the sample treated with the liquid flame retardant of the present invention showed better performance compared to the untreated sample, due to a lower total energy release.

[0218] Combustion Growth Rate (FIGRA): FIGRA is an index that represents the rate at which the HRR develops during a test. It can also be described as the acceleration of the fire given in W / s.

[0219] As shown in Figure 3C, samples treated with the flame-retardant composition of the present invention exhibit better performance than untreated samples, as indicated by the lower FIGRA value after 900 seconds. These lower values ​​indicate a slower heat generation rate and slower fire spread. Furthermore, while all Scott pine samples showed an initial high peak followed by a decrease in FIGRA value, the untreated samples maintained higher heat generation for a longer period, suggesting they were more dangerous overall than the samples containing the composition of the present invention.

[0220] Example 9: Fire Test of Scaled-Up Wood Treatment - Additional Test The Mini-SBI test disclosed in Example 8 was applied again. Samples: The following samples were tested: Scottish pine wood (PFE1, PFE2, and PFE3) treated with a liquid flame retardant composition (sample (b)) prepared according to Example 1, and further containing 2% calcium carbonate and 0.5% iron oxide. -MDF Firax: Commercially available flame-retardant MDF board - Untreated Scotts pine wood (negative control, test 416)

[0221] A series of samples were impregnated. The process parameters were 0.1 bar for 60 minutes, followed by 13 bar for 120 minutes, and dry pre-vacuum was used.

[0222] The amount of lignin-hemicellulose composition absorbed by the wood was measured. Both before and after treatment, the wood was adjusted to a moisture content of 12%, and the amount absorbed was calculated by measuring the mass difference. Variations in the wood resulted in different levels of absorption. One group of samples was divided into three groups according to their absorption levels. Sample PFE1 had an absorption level of 377 ± 56 kg / m². 3 A random selection was made from the group that achieved the specified absorption amount, and the sample PFE2 was 111±13 kg / m³. 3 A random selection was made from the group that achieved the specified absorption amount, and the sample PFE3 was 36±4 kg / m². 3 They were randomly selected from the group that achieved the required absorption amount.

[0223] In Example 8, data figures 3A, 3B, and 3C reflect values ​​obtained directly from the SBI-mini test. As previously mentioned, the apparatus used is a geometrically scaled version of the European standard SBI test.

[0224] In Example 9, the values ​​shown in Figures 4A, 4B, 4C, and 4D are "scaled" values, meaning that the values ​​obtained from the mini-SBI test were scaled so that they could be compared to the values ​​from the standard SBI test.

[0225] Scaled mean heat generation rate (HRRav(t):) Lower and more stable HRRav(t) indicates materials that release heat at a slower and more consistent rate, which can contribute to delaying flame propagation and reducing flame intensity. In contrast, higher and increasing HRRav(t) suggests materials that release heat rapidly over time, which can lead to faster flame growth and a greater fire hazard. Therefore, materials with lower and more stable HRRav(t) values ​​are considered more effective in delaying flame propagation and improving fire safety.

[0226] As shown in Figure 4A, all treated samples showed better performance than untreated samples. In particular, samples PFE1 and FIRAX had lower and more stable HRRav(t) values ​​compared to untreated samples, and are therefore considered to be more effective in delaying flame spread and improving fire safety.

[0227] Scaled total heat generation: As shown in Figure 4B, the untreated sample showed a rapid increase in heat compared to the treated sample, which suggests potentially different behavior. Here again, it is observed that sample PFE1 showed performance very similar to FIREX. Furthermore, it was observed that samples PFE2 and PFE3 showed performance closer to FIREX than the untreated sample.

[0228] For example, Table 3 reports the time to heat release (THR600) and its scaled value. A lower THR600 value indicates a slower ignition time. The Untreated Sample Percentage column shows how much faster or slower the ignition time is compared to the untreated sample for each test or material. [Table 3]

[0229] As shown in the table, all treated samples performed better than untreated samples.

[0230] Scaling combustion growth rate (S-FIGRA): In Figure 4C, each line represents the increase and subsequent decrease in fire intensity over a period of time. Initially, all samples show a peak that then decreases. This initial peak may indicate the point at which the fire begins to grow rapidly. FIRAX and sample PFE1 showed the best performance. At the start of the test, the untreated sample had the highest peak in the heat generation rate, while PFE2 and PFE3 were slightly lower, which may represent the initial combustion stage of the wood. For all treated samples, despite the initial peak, the fire was suppressed over time. Smoke generation: Figure 4D shows that, unlike the untreated sample, all treated samples effectively reduced smoke.

[0231] Example 10: Application to other cellulose-based products and resistance over time 10.1 Performance of other cellulose-based products Stationary products made from cellulose components, such as fiberboard and plywood, typically require the addition of flame retardants for safety reasons.

[0232] Two types of samples were tested: medium-density fiberboard (MDF) and three-ply plywood specimens made from pine. These commercially available specimens had dimensions of 10 cm × 10 cm × 0.3 cm and had a smooth and uniform surface to facilitate uniform application of the flame-retardant composition by brush application.

[0233] A test was conducted to determine whether the flame-retardant composition of the present invention, prepared according to sample (b) of Example 1, could be applied well by brushing and whether it had the potential to protect the installed cellulose product.

[0234] Reference Composition: For reference, a known expandable coating formulation was used. Expandable chemicals are known to cause expansion and are typically used in passive fire protection. That is, they cause expansion behind a protective charred layer, thereby providing much better insulation. This reference formulation consisted of ammonium polyphosphate (Exolit 422), melamine (Sigma), and pentaerythritol (Sigma). These components were mixed in a 3:1:1 ratio as recommended in patents and scientific literature. A polymeric aqueous dispersion (Mowilith LDM 2301) was used as a film-forming agent for the flame-retardant coating.

[0235] Preparation of coatings: Samples were conditioned at room temperature (20-25°C). MDF and plywood samples were prepared by painting one side of each specimen with a general-purpose brush. Multiple layers were applied until the specimen could no longer absorb any more of the composition, as indicated by the flow of the composition down. Typically, this saturation point was reached after 3 layers for plywood and after 6 layers for MDF.

[0236] After treatment, the wet test specimens were dried in a convection oven at 25°C for one week. Then, both the treated and untreated test specimens were allowed to set at room temperature (20-25°C) for three days before testing.

[0237] Furnace and Butane Burner Tests: Coatings formed with both the expandable reference composition and the flame-retardant composition of the present invention were annealed in a furnace at 600°C and with a butane burner. A carbon layer was observed for both compositions. The presence of a carbon layer delayed the spread of fire, confirming that the reference composition was a fair comparison to the flame-retardant composition of the present invention. However, the tests proceeded too quickly to perform comparative measurements. Therefore, a small-scale gas flame test was chosen as the test method instead.

[0238] Gas flame test setup: A small-scale gas flame test setup was used to evaluate the coating's response to direct flame. Here, combustion proceeded slowly and vertically. Ignition was applied using an industrial lighter (randomly selected from a group of 10 lighters) positioned against the surface at the lower edge of each sample. Based on the ignition pattern observed in the untreated samples (the time at which the untreated sample began to burn), a specific ignition time for the test was calculated. MDF samples were ignited for 90 seconds. Plywood samples were ignited for 45 seconds.

[0239] The main observation was that the flame-retardant composition of the present invention exhibited self-extinguishing properties and did not retain a flame after the lighter was turned off. A photographic record of the test is shown in Figure 5. The back surfaces of the treated samples were significantly less colored than those of the untreated samples, indicated by a lighter color. A similar phenomenon was observed in the expandable coated samples. As previously mentioned, the control samples ignited within the time applied.

[0240] The treated sample has a carbon layer that appears as droplets on the cellulose material. The untreated sample also forms a carbon layer (because the material itself is inherently carbonaceous), but it appears as small depressions; see Figure 6.

[0241] The horizontal spread of the flame was measured on both the front and back of the sample. For each measurement, the average of three measurements was obtained (see Table 4). [Table 4]

[0242] Despite inherent variability in cellulose products, the data consistently show that the flame-retardant composition of the present invention tends to significantly reduce flame spread. In the case of MDF samples, the effect was even better than that of the reference coating, which may be due to the easier absorption of the flame-retardant composition of the present invention compared to more hydrophobic, expandable coatings. In the case of plywood samples, the effect was less pronounced, and these samples did not absorb the composition in the same large quantities as the MDF samples.

[0243] 10.2 Accelerated Weathering Test Fireproofing treatment can significantly improve the fire resistance of cellulose products, but this protection can be substantially reduced by exposure to moisture or weathering. Flowing water, changes in moisture content, and UV radiation can also reduce the amount of flame retardant in the product. Therefore, flowing water, changes in moisture content, and UV radiation can also reduce the amount of flame retardant in the product.

[0244] For this purpose, an additional set of samples was prepared as described in Example 10.1, conditioned at 23 °C and 50% relative humidity for 2 weeks, and placed in an accelerated weathering chamber (Danish Technological Institute). 336 hours of the cycle shown in Table 5, or 28 repetitions, were carried out.

Table 5

[0245] After exposure, the samples were gently dried in a convection oven at 25 °C and conditioned at 23 °C and 50% relative humidity for 1 week. Then, the small-scale gas flame test was applied.

[0246] The plywood samples could not withstand the intensity of the accelerated weathering test because the layers separated. The flame retardant effect could not be tested, which indicated that the exposure was too severe. The layer with the flame retardant composition had a different color from the other layers, suggesting that part of the solution remained in the solution.

[0247] Surprisingly, for the MDF samples, the samples containing the flame-retardant composition of the present invention outperformed the untreated and reference expandable coatings, primarily because the samples did not degrade. Unlike the expandable coating, the composition of the present invention did not limit absorption to the outer layer, resulting in better resistance to changing conditions. Consequently, samples containing the flame-retardant composition of the present invention maintained soundness even in better conditions than the untreated sample, while samples containing the expandable coating exhibited a rough, uneven, and granular texture. The physical reaction of the expandable coating to the changing test conditions may have contributed to the failure of two of the three samples.

[0248] Furthermore, the flame-retardant effect was maintained as observed in the small gas flame test. See Table 6. [Table 6]

[0249] Example 11: Composition prepared from purified alkaline lignin, xylose, arabinose, and glucose. Hydrolysis of hemicellulose using NaOH can result in the release of various monosaccharides, including xylose, arabinose, and glucose. Therefore, these monosaccharides were used as analogs of hemicellulose in the following examples. Sample 1: Purified alkaline lignin, xylose, arabinose, and glucose were purchased from Sigma. The three monosaccharides were mixed in a ratio of 7:2:1 to mimic their original proportions in the hemicellulose of grain straw. Sample 1A contained 60% lignin and 40% hemicellulose (by weight). Sample 1B contained 40% lignin and 60% hemicellulose (by weight). Desalted water was added to each solution to reach a dry matter content of 15%. The pH was adjusted to 10.5 using a 27% NaOH solution. The compositions were stirred at a temperature of 95°C for 2 hours. Sample 2: An additional set of samples was prepared, to which 2% calcium carbonate and 0.5% iron oxide were added to the composition of Sample 1. Sample 3: An additional set of samples was prepared, and 2% calcium carbonate and 5% expansive graphite (ProGraphit Shop, Germany) were added to the composition of Sample 1.

[0250] Each of the different compositions was used to treat a wooden sample (beech wood stick – "tongue depressor") measuring 115 mm × 20 mm × 1.5 mm thick. Half the length of the stick was immersed in the corresponding solution for 20 minutes, after which excess liquid was wiped off with tissue paper, and the treated stick was dried in a 70°C convection oven for 45 minutes. The samples, along with their untreated counterparts, were allowed to set at ambient temperature for 48 hours.

[0251] The treated sticks were then tested by applying the direct flame of a candle lighter to the underside of the stick. The time required for the tongue depressor to ignite was recorded.

[0252] Results: The main observation was that all compositions exhibited self-extinguishing properties and did not maintain a flame, whereas untreated samples were completely consumed if the flame was not extinguished (see Figure 7). In particular, compositions with added expandable graphite showed superior performance by extinguishing the flame more rapidly and forming a more foamy carbon layer. This indicates that the composition acts effectively as a binder for expandable graphite, a known flame retardant additive. Furthermore, the composition also functioned as a binder for other flame retardant additives such as calcium carbonate and iron oxide.

[0253] In addition to self-extinguishing behavior, the data in Table 7 shows that when the composition contained minerals such as calcium carbonate, iron oxide, and expansive graphite, it took longer for the treated wood to ignite. [Table 7]

Claims

1. A method for preparing a flame-retardant composition containing hemicellulose and lignin components from plant materials, (i) A step of providing plant material, Here, the plant material is selected from grain straw and grass, and the process of providing it is as follows: (ii) A step of mechanically dry-treating the plant material in order to reduce its size, (iii) A step of suspending the plant material in an aqueous solution, (iv) A step of adjusting the pH to alkaline conditions, raising the temperature of the suspension, and stirring the suspension, thereby dissolving and / or dispersing the hemicellulose component and the lignin component in the aqueous solution, wherein the hemicellulose component and the lignin component are derived from the plant material, (v) A step of separating the material obtained in step (iv) into a solid fiber fraction and a liquid flame retardant fraction, wherein the liquid flame retardant fraction is a flame retardant composition containing the dissolved and / or dispersed hemicellulose and lignin components, (vi) A method comprising the optional step of concentrating the liquid flame retardant composition to increase the dry matter content percentage.

2. The method according to claim 1, wherein the temperature in step (iv) is raised to over 80°C and the pH is 9 to 12.

3. The method according to claim 1 or 2, wherein the average particle size of the plant material in step (iii) is less than 1 cm.

4. The method according to any one of claims 1 to 3, wherein the suspended plant material in step (iii) is enzymatically treated with one or more hemicellulase enzymes such as xylanase and / or ferulate esterase.

5. The method according to any one of claims 1 to 4, wherein the ratio of hemicellulose component to lignin component in the flame retardant composition is 40:60 to 60:40 based on dry matter content.

6. The method according to any one of claims 1 to 5, wherein the flame retardant composition comprises at least 60%, 70%, 80%, or 90% of hemicellulose and lignin components based on total dry matter content.

7. In step (iii), the plant material suspended in the aqueous solution, (a) A step of enzymatically treating the grain straw suspended in the aqueous solution in step (iii) with a protease and / or pectinase enzyme, (b) The mixture obtained in step (a) is optionally subjected to a wet mechanical treatment, The method according to any one of claims 1 to 6, wherein the defaxed grain straw is obtained by a method comprising the step of removing wax from the solution before adjusting the pH and raising the temperature in step (v).

8. The method according to any one of claims 1 to 7, further comprising the step of adding a flame retardant additive to the liquid flame retardant composition from step (vii) or from step (vi).

9. The method according to claim 8, wherein the flame retardant additive is selected from calcium carbonate, iron oxide, and expansive graphite.

10. A flame retardant composition that can be obtained by the method described in any one of claims 1 to 9.

11. The flame retardant composition according to claim 10, wherein the composition comprises dissolved and / or dispersed hemicellulose and lignin components in a ratio of 40:60 to 60:40 based on dry matter content.

12. The flame retardant composition according to claim 10 or 11, wherein the hemicellulose component comprises a monomer, oligomer, and / or polymer of arabinoxylan, and the lignin component comprises monomethoxylated (guaiacyl (G)), dimethoxylated (syringyl (S)), and nonmethoxylated (p-hydroxyphenyl (H)) phenylpropanoids.

13. A flame-retardant composition according to any one of claims 10 to 12, comprising a flame-retardant additive.

14. The flame retardant composition according to claim 13, wherein the flame retardant additive is selected from iron oxide, calcium carbonate, and expansive graphite.

15. Use of aqueous compositions containing dissolved and / or dispersed hemicellulose and lignin components as flame retardants.

16. Use as a flame retardant of an aqueous composition containing dissolved and / or dispersed hemicellulose and lignin components, which can be obtained by the method of any one of claims 1 to 9.

17. Use of the aqueous composition comprising the dissolved and / or dispersed hemicellulose and lignin components for improving the fire resistance of an article, wherein the article is selected from solid wood elements, wood composites, paper, corrugated cardboard, MDF, wood fibers and / or other natural fibers (such as cotton, flax, hemp, sisal, jute, etc.), and textile products.

18. Use of an aqueous composition comprising dissolved and / or dispersed hemicellulose and lignin components, which can be obtained by the method of any one of claims 1 to 9, for improving the fire resistance of an article, wherein the article is selected from solid wood elements, wood composites, paper, corrugated cardboard, MDF, wood fibers and other natural fibers (such as cotton, flax, hemp, sisal, jute), and textile products.

19. The use according to any one of claims 15 to 18, wherein the ratio of hemicellulose component to lignin component in the aqueous composition is 40:60 to 60:40 based on dry matter content (w / w).

20. The use according to any one of claims 15 to 19, wherein the hemicellulose component comprises a monomer, oligomer, and / or polymer of arabinoxylan, and the lignin component comprises monomethoxylated (guaiacyl (G)), dimethoxylated (syringyl (S)), and nonmethoxylated (p-hydroxyphenyl (H)) phenylpropanoids.

21. The use according to any one of claims 15 to 20, wherein the hemicellulose component and the lignin component constitute at least 60%, 70%, 80%, or 90% of the total dry matter content of the aqueous composition.

22. The use according to any one of claims 17 to 21, wherein the aqueous composition is applied to the surface of the article.

23. The use according to any one of claims 17 to 22, wherein the aqueous composition is applied to the article by brushing and / or spraying the composition onto the surface of the article, immersing the article in the composition, and / or impregnating the article with the composition by vacuum pressure impregnation, etc.

24. A cellulose-based or lignocellulose-based article or material comprising a flame retardant composition containing dissolved and / or dispersed hemicellulose and lignin components, which can be obtained by the method described in any one of claims 1 to 9.

25. Cellulosic or lignocellulose articles or materials according to claim 24, selected from solid wood elements, wood composites, paper, corrugated cardboard, MDF, insulation materials based on wood fibers and / or other natural fibers (such as cotton, flax, hemp, sisal, and jute), and textile products.

26. A method for improving the fire resistance of an article, comprising applying a flame-retardant composition containing dissolved and / or dispersed hemicellulose and lignin components, which can be obtained by the method described in any one of claims 1 to 9, to the article.

27. The method according to claim 26, wherein the ratio of hemicellulose component and lignin component in the aqueous composition is 40:60 to 60:40 based on dry matter content.

28. The method according to claim 26 or 27, wherein the hemicellulose component comprises a monomer, oligomer, and / or polymer of arabinoxylan, and the lignin component comprises monomethoxylated (guaiacyl (G)), dimethoxylated (syringyl (S)), and nonmethoxylated (p-hydroxyphenyl (H)) phenylpropanoids.

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