An intumescent fire retardant composition

Abstract

According to an example aspect of the present invention, there is provided an intumescent fire retardant composition comprising: an acid source comprising or consisting of ammonium phytate; and a carbon source selected from the group consisting of: carbohydrates, chemically modified lignins, tannin, and any combinations and derivatives thereof.

Description

An intumescent fire retardant compositionFIELD

[0001] The present application relates to intumescent fire-retardant compositions and uses thereof. In particular, a bio-based intumescent fire retardant (IFR) solution is described.BACKGROUND

[0002] The global demand for effective flame-retardant (FR) solutions is rapidly growing, driven by increasing regulatory pressure and the need for safer, more sustainable alternatives. This is further fuelled by the rise of wood construction in Europe, particularly in the Nordics and Germany, where wood is valued for its low environmental impact. As wood gains popularity, the need for advanced fire protection solutions becomes critical to ensure both safety and sustainability.

[0003] However, this growth is paralleled by escalating regulatory challenges, particularly within the European Union (EU). The European Chemicals Agency (ECHA) has launched a comprehensive strategy to evaluate and regulate flame retardants, with a significant focus on halogenated compounds. As a result, ECHA is expected to restrict most halogenated FRs, with an initial EU-wide proposal anticipated as early as 2025. This intensifying scrutiny underscores the urgent need for safer, more sustainable FR alternatives.

[0004] Current approaches

[0005] Phosphorus is a well-known fire retardant. Its fire-retardant mechanism involves both physical and chemical processes that reduce the flammability of materials and inhibit the spread of fire. Nitrogen-based flame retardants are another compound used to enhance the fire resistance of materials, like phosphorus-based retardants. In addition to forming a char layer and releasing free radical-blocking agents, nitrogen-based compounds release inert gases that dilute the flammable gases produced by the burning material.

[0006] The three active components in intumescent flame retardants (IFRs) responsible for the intumescent reaction are an acid source, a carbon source and a blowingagent. Each have a key role in the functionality of an IFR. The components are bound together by a binder or a bulk polymer.

[0007] Most commonly used acid source in non-halogenated flame retardants is ammonium polyphosphate (APP). Currently, APP is being used as a component primarily in intumescent paints and coatings. As APP is acquired from non-renewable chemical raw materials, recent research efforts have been targeted on the study of biomass-based acid sources for IFRs, mainly focusing on the application of phytic acid, a plant-derived compound with a high phosphorous content. As a phytic acid derivative, Feng et al. (2017) synthesized ammonium phytate (APA) via a reaction between phytic acid and urea to work as a plant-based flame retardant for cotton fabric. However, it is not successfully used in “solid” materials FR such as wood or metal. This is mainly due to difficulties in formulating a good and easy to apply coating layer using APA.

[0008] Veera Ollikainen (2024) studied use of APA, in combination with lignin, in flame-retardant coatings.

[0009] As is suggested by the name, carbon source is a carbon-containing substance that contributes to the intumescent char formation through the dehydration of its hydroxyl groups. The most frequently used carbon sources include pentaerythritol (PER) and dipentaerythritol (DPER). The high water-solubility of pentaerythritol presents some limits for its applicability as a charring agent in engineering applications. Additionally, its nonbiodegradability hinders its use in otherwise biodegradable products.

[0010] The foaming in the IFR is enhanced by a component referred as blowing agent. The blowing agent is an organic compound that decomposes during the melting of the matrix and the dehydration. The decomposition releases a large volume of nonflammable gases that get constrained in the melted matrix, making the carbon-mass foam and producing the porous insulating char layer. The most effective and commonly used blowing agent in IFRs is a substance called melamine (2.4.6-triamino-1.3.5-triazine). In 2023 melamine was included in the EU’s list of substances of very high concern (SVHC) as a substance having probable serious effects to human health and to the environment (ECHA, 2022). The attempts to substitute melamine with a non-toxic substance, such as urea, have so far yielded unsatisfactory results (Zybina and Gravit, 2020) and no comprehensive research studies on the topic of replacing melamine have not yet been published.

[0011] Problems of the current approaches

[0012] Current flame retardants, whether halogenated or non-halogenated, often contain harmful substances like melamine (the most commonly used blowing agent in intumescent FR solutions today) and other chemicals listed as substances of very high concern (SVHC) by the EU, which are slated for future restriction or phase-out.

[0013] Thus, there is a need for advanced fire protection solutions that ensure both safety and sustainability.

[0014] Embodiments of the present invention aim at solving at least some of the problems in the known approaches.SUMMARY OF THE INVENTION

[0015] The invention is defined by the features of the independent claims. Some specific embodiments are defined in the dependent claims.

[0016] According to a first aspect of the present invention, there is provided an intumescent fire retardant composition comprising: an acid source comprising or consisting of ammonium phytate; and a carbon source selected from the group consisting of: carbohydrates, lignin, chemically modified lignins, tannin, and any combinations and derivatives thereof.

[0017] According to a second aspect of the present invention, there is provided an intumescent fire retardant coating composition comprising the intumescent fire retardant composition according to the first aspect.

[0018] According to a third aspect of the present invention, there is provided a method comprising: applying the intumescent fire retardant composition according to the first aspect or the intumescent fire retardant coating composition according to the second aspect onto a surface of a solid article.

[0019] According to a fourth aspect of the present invention, there is provided use of the intumescent fire retardant composition according to the first aspect for treating wood, such as for impregnating or coating wood.

[0020] According to a fifth aspect of the present invention, there is provided use of ammonium phytate in combination with a bio-based carbon source as an additive in a paint, for example as an intumescent fire retardant additive in a standard household paint.

[0021] Various embodiments of the first aspect, the second aspect, the third aspect, the fourth aspect or the fifth aspect may comprise one or more features from the following bulleted list:• The intumescent fire retardant composition comprises at least 15 wt-%, such as at least 20 wt-%, such as at least 30 wt-%, such as at least 40 wt-% of ammonium phytate, calculated from the total weight of the intumescent fire retardant composition.• The intumescent fire retardant composition comprises 15 to 80 wt-%, such as 20 to 70 wt-%, such as 30 to 50 wt-% of ammonium phytate, calculated from the total weight of the intumescent fire retardant composition.• The intumescent fire retardant composition comprises less than 80 wt-%, such as less than 70 wt-%, such as 30 to 60 wt-% of the acid source(s), such as ammonium phytate, calculated from the total weight of the intumescent fire retardant composition.• The intumescent fire retardant composition comprises at least 0.5 wt-%, such as at least 1 wt-%, such as at least 2 wt-%, such as 2 to 10 wt-% of the carbon source, calculated from the total weight of the intumescent fire retardant composition.• The intumescent fire retardant composition comprises less than 15 wt-% of the carbon source, calculated from the total weight of the intumescent fire retardant composition.• The weight ratio of the carbon source and the ammonium phytate is in the range of 1 :100 to 1 :10.• The carbon source comprises or consists of carbohydrate(s).The carbon source comprises or consists of covalently modified lignin, such as urea-modified lignin.The carbon source is selected from the group consisting of: chitosan, alginate, urea- modified lignin, cellulose, tannin, and any combinations and derivatives thereof.• The carbon source comprises or consists of chitosan.• The carbon source comprises or consists of alginate.• The carbon source comprises or consists of tannin.• The carbon source comprises or consists of cellulose, such as microcrystalline cellulose.• The average molecular weight Mw of the carbon source is at least 1 000 g / mol, such as at least 5 000 g / mol, such as at least 10 000 g / mol.• The carbon source comprises functional groups selected from the group consisting of carboxylate groups, hydroxyl groups, amino groups, carbonyl groups, and any combinations thereof.• The thermal degradation temperature of the carbon source is lower than 320 °C, such as lower than 310 °C, such as lower than 300 °C.• The intumescent fire retardant composition further comprises a binder, such as a polymeric binder, such as a latex binder.• The binder is selected from the group consisting of bio-based binders.• The intumescent fire retardant composition comprises at least 5 wt-%, such as at least 10 wt-%, such as at least 20 wt-% of the binder, calculated from the total weight of the intumescent fire retardant composition.• The thermal degradation temperature of the binder is higher than the thermal degradation temperature of the carbon source.• The onset thermal degradation temperature of the binder is higher than the onset thermal degradation temperature of the carbon source, wherein the onset thermal degradation temperature is the temperature at which 5 wt-% mass loss has occurred.• The thermal degradation temperature of the binder is higher than 300 °C, such as higher than 310 °C, such as higher than 320 °C.• The intumescent fire retardant composition is an intumescent fire retardant paint composition or an intumescent fire retardant lacquer composition or an intumescent fire retardant coating composition.• The ammonium phytate is capable of acting as an acid source and as a blowing agent.• The carbon source is capable of acting also as a film-forming agent.• The intumescent fire retardant composition comprises less than 5 wt-%, in total, of fossil-based acid sources, fossil-based carbon sources and fossil-based blowing agents, calculated from the total weight of the intumescent fire retardant composition.• The intumescent fire retardant composition comprises less than 1 wt-% of fossilbased materials, preferably being substantially free from fossil-based materials, calculated from the total weight of the intumescent fire retardant composition.• All acid sources and all carbon sources of the intumescent fire retardant composition are plant-derived.• The intumescent fire retardant coating composition is substantially transparent.• The intumescent fire retardant coating composition is an intumescent fire retardant paint composition.• The intumescent fire retardant coating composition is an intumescent fire retardant red clay paint composition.• The solid article is a wood-based article or a metal article or a textile.Said applying produces a coating layer on said surface.Said additive is mixed with the paint to obtain an intumescent fire retardant paint, wherein the intumescent fire retardant paint comprises at least 15 wt-%, such as 15to 80 wt-% of ammonium phytate and 2 to 10 wt-% of the bio-based carbon source, calculated from the total weight of the intumescent fire retardant paint.

[0022] Advantages

[0023] An objective of some embodiments of the invention is to use mainly plant / bio-based materials as functional raw materials in an intumescent fire retardant (IRF) solution.

[0024] The benefits may include a discovery of very effective fire retardant solutions, with no drawback of harmful substances and effectively complying with the EU’s stringent regulatory environment, which is increasingly mandating a shift from toxic flame retardants to safer, non-toxic alternatives.

[0025] Some embodiments may enable formulating a fully transparent fire retardant coating or lacquer.BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIGURE 1 shows an illustration of the intumescent process and its practical end outcome according to some embodiments of the present invention.

[0027] FIGURE 2 shows ammonium phytate synthesization according to some embodiments of the present invention.

[0028] FIGURES 3A-3D represent the materials’ performance in different flame retardant tests according to some embodiments of the present invention.

[0029] FIGURE 4 illustrates cone calorimeter ignition and heat release comparisons of uncoated wood, leading commercial (toxic) IFR paint, and three of the bio-based compounds invented here according to some embodiments of the present invention.

[0030] FIGURE 5A and 5B illustrate the needed order of thermal degradation of the char source and the accompanying binder according to some embodiments of the present invention.

[0031] FIGURES 6A and 6B show examples of our bio-based intumescent solution used within a traditional Red Clay paint (“punamultamaali” in Finnish) according to some embodiments of the present invention.EMBODIMENTS

[0032] DEFINITIONS

[0033] The terms “fire retardant” and “flame retardant” may be used interchangeably.

[0034] The terms “intumescent fire retardant composition”, “intumescent fire retardant solution” and “intumescent fire retardant system” may be used interchangeably.

[0035] The terms “carbon source”, “carbonaceous source” and “char source” may be used interchangeably.

[0036] Unless otherwise stated herein or clear from the context, any percentages referred to herein are expressed as percent by weight based on a total weight of the respective composition.

[0037] As used herein, unless otherwise indicated, the term “average molecular weight” refers to a weight average molecular weight (also abbreviated “Mw” or “Mw”).

[0038] As used herein, “biopolymer” stands for polymers produced from natural sources either chemically synthesized from a biological material or entirely biosynthesized by living organisms.

[0039] We have surprisingly observed that ammonium phytate (APA) may provide advantages when used as a component (as an acid source) of a fire-retardant composition together with certain bio-based materials, particularly carbon sources, and optionally also in combination with a binder. These advantages are particularly enhanced in intumescent fire-retardant compositions.

[0040] In some embodiments, it has been observed that the roles of the biomaterials in the present composition may be tailored, for example to reach important features and properties of a practical fire-retardant coating, such as film forming properties, carbon content, role as binder, rheology properties and / or drying properties of the final coating.

[0041] In an aspect of the present invention, there is provided an intumescent fire retardant composition comprising: an acid source comprising or consisting of ammonium phytate; and a carbon source selected from the group consisting of: carbohydrates, chemically modified lignins, tannin, and any combinations and derivatives thereof.

[0042] Further, in some embodiments, what was invented is a specific arrangement of the order of thermal stabilities of raw materials in intumescent fire-retardant coatings - in particular, when bio-based materials are used. Especially bio-based carbon-rich char sources often possess high thermal stability, higher than typical binders. This will then result in fire retardant coating disintegrating before the blowing agent can form the foam into the coating. When using fossil-based carbon source, however, this normally does not pose a problem, due to the fact that fossil carbon materials have a lower thermal degradation temperature than their “original” biomass-based materials of origin. This is most likely due to hundreds of millions years carbonization and degradation process taking place in the carbon in the earth’s crust.

[0043] In some embodiments, what is invented here, is the specific order of thermal disintegration of raw materials, as follows: The bio-based carbon-rich char source (e.g. lignin, cellulose or tannin) may be selected or chemically modified so that it will disintegrate in a lower temperature than the selected binder. Or, as an alternative embodiment: The binder will be selected so that it will disintegrate in a higher temperature than the selected char source.

[0044] The benefit of some embodiments of this invention is that the initially high thermal stability biomaterials can be used with typically used binders, or binders can be developed to exceed the thermal degradation temperature of the carbon source.

[0045] An embodiment of this invention describes also making of a practical application of said TGA behaviour which describes a working thermal degradation sequence especially when using bio-based binders and / or carbon source in intumescent fire retardant systems.

[0046] In some embodiments, the novelty in the production here lies in the exclusive way of production of the materials where an energy-efficient oven drying process replaces conventional freeze-drying technology. This approach may facilitate mass production and enhance scalability also the use of naturally-occurring active compounds, combined with the use of biopolymers.

[0047] In a preferred embodiment, the invention has all the major components (acid source, char source and blowing agent) of an IFR solution made essentially of bio-based materials.

[0048] The use cases of the invention may include all currently used IFR applications in wood, metal and textile industry.

[0049] As a special application, in some embodiments, traditional (often protected by the law) historical buildings can be protected with a solution of a traditional plant based red clay paint added with our plant based IFR raw material for fire protection of the invaluable historical buildings.

[0050] In some embodiments, we propose using “punamulta”, Red Clay paint (Fe2O3’H2O) as a traditional house paint system, but added with the above described biobased intumescent fire retardant system. This will then create a natural ingredient based traditional house paint system used especially in Nordic countries for hundreds of years - even in the prehistoric era - with bio-based fire retardant properties.

[0051] Acid source

[0052] In the present invention, the acid source of the intumescent fire-retardant composition comprises or consists of ammonium phytate.

[0053] Preferably, the intumescent fire retardant composition comprises at least 15 wt-%, such as at least 20 wt-%, such as at least 30 wt-%, such as at least 40 wt-%, such as such as at least 50 wt-% of ammonium phytate, calculated from the total weight of the intumescent fire retardant composition.

[0054] In some embodiments, the intumescent fire retardant composition comprises 15 to 80 wt-%, such as 30 to 50 wt-% of ammonium phytate, calculated from the total weight of the intumescent fire retardant composition. Very high concentrations of APA may result in drying problems. In other words, excessive APA content can make the coating sticky and difficult to dry.

[0055] In some embodiments, the acid source is a combination of ammonium phytate and a further plant-derived compound capable of acting as an acid source.

[0056] In some embodiments, the sole acid source of the intumescent fire retardant composition is ammonium phytate.

[0057] In some embodiments, the intumescent fire-retardant composition consists of the acid source, the carbon source and optionally water.

[0058] Carbon source

[0059] The carbon source may comprise or consist of a biopolymer or biopolymers, such as chitosan, alginate, lignin, chemically modified lignin, tannin, cellulose, microcrystalline cellulose, and derivatives and mixtures thereof.

[0060] The carbon source may act as a film forming agent.

[0061] Preferably, the intumescent fire retardant composition comprises at least 0.5 wt-%, such as at least 1 wt-%, such as at least 2 wt-%, such as 2 to 10 wt-%, such as 2 to 5 wt-% of the carbon source(s), calculated from the total weight of the intumescent fire retardant composition.

[0062] In an embodiment, the intumescent fire retardant composition comprises less than 10 wt-% of the carbon source, calculated from the total weight of the intumescent fire retardant composition.

[0063] It is advantageous to keep the concentration of the carbon source below a certain concentration limit in the IFR composition. High carbon source concentrations may lead to reduced intumescence or even complete absence of intumescence.

[0064] In an embodiment, the weight ratio of the carbon source and the ammonium phytate is in the range of 1 : 100 to 1 :10.

[0065] In some embodiments, the carbon source comprises or consists of covalently modified lignin, such as urea-modified lignin or aminated lignin.

[0066] Various modified lignins, such as modified kraft lignins, may be used as carbon sources in some embodiments. For example, the carbon source may comprise amino-functionalized or aminated lignin. Preferably, the modified lignin has a lower (onset) thermal degradation temperature than kraft lignin.

[0067] In some embodiments, the carbon source is selected from the group consisting of: chitosan, alginate, urea-modified lignin, cellulose, tannin, and any combinations and derivatives thereof.

[0068] In an embodiment, the carbon source comprises or consists of chitosan.

[0069] In an embodiment, the carbon source comprises or consists of alginate.

[0070] In an embodiment, the carbon source comprises or consists of tannin.

[0071] In an embodiment, the carbon source comprises or consists of cellulose, such as microcrystalline cellulose.

[0072] In an embodiment, the average molecular weight Mw of the carbon source is at least 1 000 g / mol, such as at least 5 000 g / mol.

[0073] In some embodiments, the carbon source comprises functional groups selected from the group consisting of carboxylate groups, hydroxyl groups, amino groups, carbonyl groups, and any combinations thereof.

[0074] Preferably, the thermal degradation temperature of the carbon source is lower than 320 °C, such as lower than 310 °C, such as lower than 300 °C.

[0075] The carbon source may be capable of acting also as a film-forming agent.

[0076] An advantage of using chitosan or alginate as the carbon source is that adhesion properties of a paint may be improved.

[0077] Chitosan may improve the film forming and drying properties of the composition.

[0078] Binder

[0079] In some embodiments, the intumescent fire retardant composition further comprises a binder, such as a polymeric binder, such as a latex binder.

[0080] In some embodiment, the binder may be selected from the group consisting of bio-based binders.

[0081] In an embodiment, the composition comprises at least 5 wt-%, such as at least 10 wt-%, such as at least 20 wt-% of the binder, calculated from the total weight of the intumescent fire retardant composition.

[0082] Preferably, the (onset) thermal degradation temperature of the binder is higher than the thermal degradation temperature of the carbon source.

[0083] In an embodiment, the thermal degradation temperature of the binder is higher than 300 °C, such as higher than 310 °C, such as higher than 320 °C.

[0084] In some embodiments, the interconnected feature of the binder and the carbon source is their related thermal disintegration temperatures: The binder should preferably have a higher thermal disintegration temperature than the selected carbon source, to keep the char layer together during the intumescent charring process.

[0085] Blowing agent

[0086] Preferably, APA functions as a blowing agent, and therefore no further blowing agent is needed or present in the composition.

[0087] Bio-based composition

[0088] In an embodiment, the intumescent fire retardant composition comprises less than 5 wt-%, in total, of fossil-based acid sources, fossil-based carbon sources and fossilbased blowing agents, calculated from the total weight of the intumescent fire retardant composition.

[0089] In an embodiment, the intumescent fire retardant composition comprises less than 1 wt-% of fossil-based materials, preferably being substantially free from fossil-based materials, calculated from the total weight of the intumescent fire retardant composition.

[0090] In some embodiments, all acid sources and all carbon sources of the composition are plant-derived.

[0091] Use in paints, lacquers and coatings

[0092] The present invention also provides an intumescent fire retardant coating composition comprising the intumescent fire retardant composition.

[0093] The coating composition, such as a paint composition, may be prepared by mixing the intumescent fire retardant composition with a commercial paint in a weight ratio in the range 30:70 to 70:30, such as 40:60 to 60:40, for example 50:50.

[0094] The intumescent fire retardant coating composition may be a substantially transparent lacquer composition or a substantially transparent coating composition.

[0095] In an embodiment, the intumescent fire retardant coating composition is an intumescent fire retardant paint composition.

[0096] In an embodiment, the intumescent fire retardant coating composition is an intumescent fire retardant red clay paint composition.

[0097] The present invention also provides a method comprising applying the intumescent fire retardant composition or the intumescent fire retardant coating composition onto a surface of a solid article.

[0098] In some embodiments, the solid article is a wood-based article or a metal article or a textile. The wood-based article may be a wood board.

[0099] In some embodiments, said applying produces a coating layer on said surface.

[0100] The present invention also provides use of the intumescent fire retardant composition for treating wood, such as for impregnating or coating wood.

[0101] The present invention also provides use of ammonium phytate in combination with a bio-based carbon source as an additive in a paint, for example as an intumescent fire retardant additive in a standard household paint.

[0102] For example, said additive is mixed with the paint to obtain an intumescent fire retardant paint, wherein the intumescent fire retardant paint comprises at least 15 to 80 wt-% of ammonium phytate and 2 to 10 wt-% of the bio-based carbon source, calculated from the total weight of the intumescent fire retardant paint.

[0103] Particular embodiments of the present invention may provide one or more of the advantages discussed in the following.

[0104] APA is self-intumescent and may function as a multifunctional component, acting simultaneously as an acid source, a carbon source, and a blowing agent.

[0105] Coating issues may be avoided. A challenge with APA-based coatings is their very slow drying process: The surface tends to remain sticky until fully dry, and because APA is hygroscopic, the coating often stays tacky over time. In some embodiments of the present invention, these disadvantages may be alleviated or avoided.

[0106] Mixing APA with biopolymers, such as chitosan, alginate, or lignin, may improve the coating performance. These biopolymers may help the coating dry faster and reduce surface stickiness.

[0107] Expansion behaviour: APA alone may show the highest expansion. However, increasing the chitosan content in an APA-chitosan blend may reduce the overall expansion.

[0108] Surface quality: A higher biopolymer concentration in the APA mixture may result in a drier and smoother coating surface.

[0109] Notably, chitosan may serve a dual function: It may act both as a binder and as a carbon source.

[0110] Examples

[0111] FIGURE 1 illustrates the intumescent reaction.

[0112] In an example, naturally occurring high-phosphorus and nitrogen-content active flame-retardant materials ammonium phytate (APA) was synthesized through the reaction between phytic acid and urea. Phytic acid is a plant-derived compound, possesses a significant phosphorus content and is present in most cereals and oilseeds.. The synthesization is illustrated in FIGURE 2. The fire-retardant active material can then be mixed with various carbonaceous sources, such as chitosan, alginate, lignin, and cellulose, for enhanced char formation and enriched protection for the substrate. The polymer acts as a binder for paint formulation and enhances char formulation for intumescent flameretardant protection.

[0113] Ammonium phytate melts at a low temperature, say 150 °C, and starts to produce foam. As the foam is formed at early temperature. At high temperature this foam converts to char like structure, then this char prevents heat transfer to the substrate, say the wood surface. In other words, in an embodiment, APA can (at least partly) replace specialized acid source, blowing agent and carbon source through the reactions it undergoes as temperature rises in an event of fire.

[0114] In some embodiments, an energy-efficient synthesis process is employed to produce these versatile flame-retardant materials, which exhibit exceptional fire-resistant properties. They have been successfully tested in various applications, including wood coatings, wood impregnation, wool for heat insulation, and foam-based acoustic elements, all demonstrating strong intumescent flame-retardant characteristics. Additionally, the material can be used as an additive in standard household paints, transforming them intofire retardant solutions. FIGURE 3 represents the materials performance in different flameretardant tests.

[0115] In some embodiments, the synergistic effects of naturally-occurring phosphorus and nitrogen-based flame retardants are being used to develop bio-based flame retardants. Renewable biomaterials rich in phosphorus and nitrogen are being utilized to formulate fire-retardant materials. The fire retardancy of these materials is further enhanced by the addition of biopolymers, which are also incorporated into paint formulations for coating applications. This combined approach optimizes the intumescent effect, providing superior flame-retardant performance (FIGURE 4).

[0116] The content of the drawings is explained in more detail in the following.

[0117] FIGURE 1 shows an illustration of the intumescent process and its practical end outcome according to some embodiments of the present invention.

[0118] FIGURE 2 shows ammonium phytate synthesization process according to some embodiments of the present invention.

[0119] FIGURES 3A-3D represent the materials’ performance in different flame retardant tests according to some embodiments of the present invention.

[0120] FIGURES 3A-3D: The samples contained APA, a carbon source, and optionally a cross-linker (DICY). The carbon sources were chitosan, alginate, lignin, PER and MCC. A commercial IFR paint was used as a reference (sample “Ref’).

[0121] Table 1. Sample compositions (grams).

[0122] Substrates were coated with the samples of Table 1. As the coating substrate, softwood spruce board in dimensions 20 mm x 10 cm x 20 cm was used for vertical flame testing, and 20 mm x 10 cm x 10 cm for the cone calorimeter tests. For the determination of expansion factor in muffle furnace test, 5 mm thick acid resistant steel plates were cut in 2.5 x 3 cm pieces and used as substrate. The thickness of the coating layers on all substrates was standardized to correspond to the recommended wet application thickness of the commercial IFR paint (350 g / m2).

[0123] In the bar graph of FIG. 3A, the samples from left to right were: Ref, APA,Lignin-APA, PER-APA, MCC-APA, Chitosan-APA, Alginate-APA, Lignin-APA-DICY,and PER-APA-DICY. The bar graph shows “Expansion number of times” (light orange bars, i.e. left bars) and “Weight residue %” (green bars, i.e. right bars) for each sample. Elevated expansion factors indicate effective intumescence. High weight residues indicate high charring capability of the carbon source. The highest expansion factor was observed for the combination of chitosan and APA.

[0124] In FIG. 3B, in the graphs showing Rate of heat release (kW / m2) versus Time, the samples were: Blank (black), Ref (red), APA (blue), Lignin-APA (green), PER-APA (lila), MCC-APA (light brown), Chitosan-APA (turquoise, the lowermost line in the range 300 to 900 s), Alginate-APA (brown), Lignin-APA-DICY (mud brown), and PER-APA- DICY (orange).

[0125] The photographs of FIG. 3C show results from in-house screening-type muffle furnace tests, before (left) and after (right) the heat treatment. Steel plates coated with sample were heat treated in 500 °C for 3 minutes using Naber L51 / s muffle furnace.

[0126] The performance of coated wood samples under exposure to direct flame was tested using an in-house vertical flame test method. Gester GT-C35 Flammability tester was adjusted for the purpose of testing wooden samples. The equipment composed of a burning chamber, where the sample was placed vertically at 2 cm distance from a propane burner set in 45° angle. The length of the flame was adjusted to 2 cm. Each sample was burned for 90 s to observe the burning behaviour. The photographs of FIG. 3D show results from the vertical flame testing. Based on the bum mark acquired at vertical flame testing (char partially scraped off from 90 s bum mark), the performance of the samples when exposed to direct flame was assessed qualitatively.

[0127] FIGURE 4 illustrates cone calorimeter ignition and heat release comparisons (ISO 5660-1) of uncoated wood (“Blank”, in grey), leading commercial (toxic) IFR paint (“Comm FR paint”, in red), and three of the bio-based compounds (lignin-APA in light green, alginate-APA in medium green, and chitosan-APA in dark green, depicted as “Bio coating 1, 2 and 3, respectively) invented here according to some embodiments of the present invention.

[0128] FIGURES 5A-5B present TGA of individual IFR components.

[0129] FIGURE 5A illustrates the advantageous order of thermal degradation of the char source (lignins, PER) and the accompanying binder (Vinnapas, Emultex) according to some embodiments of the present invention. The samples contained:KL: kraft lignin,UMLig: urea-modified lignin,PER: pentaerythritol,Vinnapas, a latex binder based on vinyl acetate and ethylene,Emultex, a latex binder based on vinyl acetate and vinyl versatate,APP: ammonium polyphosphate,MEL: melamine.

[0130] The urea-modification of lignin reduced the thermal stability of lignin.

[0131] FIGURE 5B is a simplified version of FIG. 5A, without the arrows and the related explanatory text.

[0132] FIGURES 6A and 6B show examples (bum marks from vertical flame testing) of bio-based intumescent solutions used within a traditional Red Clay paint (“punamultamaali” in Finnish) according to some embodiments of the present invention.

[0133] Preparation and analysis of the sample: An intumescent fire-retardant composition according to an embodiment was included in a red clay paint. A wooden substrate was painted with the paint, and fire-retardant behaviour of the painted surface was examined by vertical flame testing.

[0134] Further examples

[0135] APA was synthesized from its raw materials phytic acid and urea. During the synthesizing, chitosan was added to improve its solubility.

[0136] Various APA+chitosan solutions were prepared. These can then be added e.g. in 50:50 weight ratio into a paint (solution : paint).

[0137] Two samples were prepared (Sample 1 and Sample 2) with the compositions (wt-%) shown in Table 2. The samples were prepared by combining all ingredients asshown in Table 2 for each sample, and heating at 110 °C for one hour with continuous stirring.

[0138] Table 2.

[0139] After the drying step, the dried samples had a consistency of about 70%. The chitosan content in the dried samples was 11% (Sample 1) and 6% (Sample 2), calculated from the total weight of the sample.

[0140] The dried Samples 1 and 2 were mixed with a paint or lacquer product (about 50:50 w / w), to obtain Paint sample 1 and Paint sample 2, respectively. Table 3 gives the compositions (wt-%) of the Paint samples.

[0141] It was observed that Sample 1 did not show intumescence. Sample 2 showed intumescence.

[0142] Table 3.

[0143] A further sample (Sample 3 and respective Paint sample 3) containing no chitosan and only APA was also prepared and tested. Sample 3 showed intumescence. However, absence of chitosan resulted in poor film forming properties, which is a desired property for a working paint or lacquer coating.

[0144] An alginate-based sample (Sample 4) was also tested. Sample 4 contained 7 wt-% alginate, 29 wt-% APA and 64 wt-% water, and it worked well, showing intumescence.

[0145] CONCEPTS

[0146] The following concepts illustrate exemplary embodiments of the invention.

[0147] 1. An Intumescent Fire Retardant (IFR) system traditionally comprising of acid source, carbon source and blowing agent, that is characterized by having essentially major portion or completely of the active IFR raw materials of bio-based origin.

[0148] 2. The IFR system described in concept 1, containing a binder that has a higher thermal degradation temperature (TGA) than that of the carbon source.

[0149] 3. The IFR system described in concept 1, containing ammonium phytate(APA) as a functional component.

[0150] 4. The IFR system in concepts 1 and 3, wherein APA functions so that it essentially replaces both an acid source and a blowing agent in the IFR solution.

[0151] 5. The IFR system in concepts 1 and 3-4, wherein APA functions so that it essentially replaces a specific carbon source.

[0152] 6. The IFR system described in concept 1, or alternatively concepts 2-3,which is being applied in a traditional Red Clay paint “punamultamaali”.

[0153] It is to be understood that the embodiments of the invention disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.

[0154] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment.

[0155] As used herein, a plurality of items, structural elements, compositional elements, and / or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present invention may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations of the present invention.

[0156] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

[0157] While the forgoing examples are illustrative of the principles of the presentinvention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below.

[0158] The verbs “to comprise” and “to include” are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of “a” or “an”, i.e. a singular form, throughout this document does not exclude a plurality.INDUSTRIAL APPLICABILITY

[0159] The present invention is industrially applicable at least in manufacturing of intumescent fire-retardant materials.ACRONYMS LISTAPA ammonium phytateFR fire retardantIFR intumescent fire retardantAPP ammonium polyphosphateKL kraft ligninUMLig urea-modified ligninMCC microcrystalline celluloseMEL melaminePER pentaerythritolDPER dipentaerythritolDICY dicyandiamideTGA thermogravimetric analysisSVHC substance of very high concernCITATION LISTNon Patent Literature Feng et al., Carbohydrate Polymers 175 (2017) 636-644.Veera Ollikainen, Master’s thesis, Aalto University, 2024.Zybina and Gravit, Intumescent Coatings for Fire Protection of Building Structures and Materials. Springer Nature Switzerland, 2020.

Claims

CLAIMS:

1. An intumescent fire retardant composition comprising:- an acid source comprising or consisting of ammonium phytate; and- a carbon source selected from the group consisting of: carbohydrates, chemically modified lignins, tannin, and any combinations and derivatives thereof2. The intumescent fire retardant composition according to any of the preceding claims, comprising 15 to 80 wt-%, such as 30 to 50 wt-% of ammonium phytate, calculated from the total weight of the intumescent fire retardant composition.

3. The intumescent fire retardant composition according to any of the preceding claims, comprising at least 0.5 wt-%, such as at least 1 wt-%, such as at least 2 wt-% of the carbon source, calculated from the total weight of the intumescent fire retardant composition.

4. The intumescent fire retardant composition according to any of the preceding claims, comprising less than 10 wt-% of the carbon source, calculated from the total weight of the intumescent fire retardant composition.

5. The intumescent fire retardant composition according to any of the preceding claims, wherein the weight ratio of the carbon source and the ammonium phytate is in the range of 1 :100 to 1 :10.

6. The intumescent fire retardant composition according to any of the preceding claims, wherein the carbon source comprises or consists of covalently modified lignin, such as urea-modified lignin.

7. The intumescent fire retardant composition according to any of the preceding claims, wherein the carbon source is selected from the group consisting of: chitosan, alginate, urea-modified lignin, cellulose, tannin, and any combinations and derivatives thereof.

8. The intumescent fire retardant composition according to any of the preceding claims, wherein the carbon source comprises or consists of chitosan.

9. The intumescent fire retardant composition according to any of the preceding claims, wherein the carbon source comprises or consists of alginate.

10. The intumescent fire retardant composition according to any of the preceding claims, wherein the carbon source comprises or consists of tannin.

11. The intumescent fire retardant composition according to any of the preceding claims, wherein the average molecular weight Mw of the carbon source is at least 1 000 g / mol.

12. The intumescent fire retardant composition according to any of the preceding claims, wherein the carbon source comprises functional groups selected from the group consisting of carboxylate groups, hydroxyl groups, amino groups, carbonyl groups, and any combinations thereof.

13. The intumescent fire retardant composition according to any of the preceding claims, wherein the thermal degradation temperature of the carbon source is lower than 320 °C, such as lower than 310 °C, such as lower than 300 °C.

14. The intumescent fire retardant composition according to any of the preceding claims, which further comprises a binder, such as a polymeric binder, such as a latex binder.

15. The intumescent fire retardant composition according to any of the preceding claims, wherein the binder is selected from the group consisting of bio-based binders.

16. The intumescent fire retardant composition according to any of the preceding claims, wherein the composition comprises at least 5 wt-%, such as at least 10 wt-%, such as at least 20 wt-% of the binder, calculated from the total weight of the intumescent fire retardant composition.

17. The intumescent fire retardant composition according to any of the preceding claims, wherein the onset thermal degradation temperature of the binder is higher than the onset thermal degradation temperature of the carbon source.

18. The intumescent fire retardant composition according to any of the preceding claims, wherein the thermal degradation temperature of the binder is higher than 300 °C, such as higher than 310 °C, such as higher than 320 °C.

19. The intumescent fire retardant composition according to any of the preceding claims, which is an intumescent fire retardant paint composition or an intumescent fire retardant lacquer composition or an intumescent fire retardant coating composition.

20. The intumescent fire retardant composition according to any of the preceding claims, wherein the ammonium phytate is capable of acting as an acid source and as a blowing agent.

21. The intumescent fire retardant composition according to any of the preceding claims, wherein the carbon source is capable of acting also as a film-forming agent.

22. The intumescent fire retardant composition according to any of the preceding claims, comprising less than 5 wt-%, in total, of fossil-based acid sources, fossil-based carbon sources and fossil-based blowing agents, calculated from the total weight of the intumescent fire retardant composition.

23. The intumescent fire retardant composition according to any of the preceding claims, comprising less than 1 wt-% of fossil-based materials, preferably being substantially free from fossil-based materials, calculated from the total weight of the intumescent fire retardant composition.

24. The intumescent fire retardant composition according to any of the preceding claims, wherein all acid sources and all carbon sources of the intumescent fire retardant composition are plant-derived.

25. An intumescent fire retardant coating composition comprising the intumescent fire retardant composition according to any of the preceding claims.

26. The intumescent fire retardant coating composition according to claim 25, which is substantially transparent.

27. The intumescent fire retardant coating composition according to claim 25, which is an intumescent fire retardant paint composition.

28. The intumescent fire retardant coating composition according to claim 27, which is an intumescent fire retardant red clay paint composition.

29. A method comprising: applying the intumescent fire retardant composition according to any of claims 1 to 24 or the intumescent fire retardant coating composition according to any of claims 25 to 28 onto a surface of a solid article.

30. The method according to claim 29, wherein the solid article is a wood-based article or a metal article or a textile.

31. The method according to claim 29 or 30, wherein said applying produces a coating layer on said surface.

32. Use of the intumescent fire retardant composition according to any of claims 1 to 24 for treating wood, such as for impregnating or coating wood.

33. Use of ammonium phytate in combination with a bio-based carbon source as an additive in a paint, for example as an intumescent fire retardant additive in a standard household paint.

34. The use according to claim 33, wherein said additive is mixed with the paint to obtain an intumescent fire retardant paint, wherein the intumescent fire retardant paint comprises at least 30 wt-% of ammonium phytate and 0.5 to 15 wt-% of the bio-based carbon source, calculated from the total weight of the intumescent fire retardant paint.

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