Intumescent coating composition

Abstract

A solvent-based intumescent coating composition comprising: a) at least 5.0 wt% of a polyethylene ester binder and / or a (meth)acrylic binder relative to the total weight of the intumescent coating composition; b) an acid-generating agent; c) a carbon donor; and d) at least 4.0 wt% of dicyandiamide relative to the total weight of the intumescent coating composition; wherein the weight ratio of component b):c) is in the range of 2:1 to 4:1.

Description

Technical Field

[0001] This invention relates to an intumescent coating composition and a substrate coated with the intumescent coating. The invention also relates to a method of using an intumescent coating to coat a substrate and the use of the intumescent coating composition to protect a substrate from fire and / or heat. Furthermore, the invention relates to a method for improving the quality of the char layer (char, carbon, carbonized layer) produced by the intumescent coating when it is exposed to fire and / or heat. Background Technology

[0002] Steel is commonly used as a building material and has many advantages. However, it is known that structural steel can rapidly lose its structural integrity in the event of a fire if left unprotected. Therefore, some form of passive fire protection is known to protect steel, with intumescent coatings being one example. Passive fire protection is designed to slow the rate of temperature rise in structural steel, significantly extending the time before any form of structural collapse occurs, and thus allowing time for evacuation and preservation of valuable assets.

[0003] At elevated temperatures, intumescent coatings (typically applied directly to the substrate or over an existing coating already applied to the substrate) decompose to form a porous carbonaceous layer. This layer expands into foam by releasing gases, which are then trapped within the carbon layer. The foamed carbon layer forms an insulating layer that protects the underlying substrate from heat damage. Intumescent coatings generally offer advantages over other available forms of passive fire protection, such as in their lightweight and environmental durability.

[0004] The formed porous carbonaceous layer and its integrity are crucial to the quality and performance of intumescent coatings. Any defects can lead to cracks in the carbon layer, and in extreme cases, the carbon layer will fail to protect the substrate from the heat of a fire.

[0005] One specific type of defect is nodule. Nodules are structural features on the surface of a carbon layer, characterized by their circular or irregular shape. Nodules are weak points in the carbon layer, which can lead to premature flaking, cracking, and irregular performance. Nodules can form in various sizes, with larger nodules being more detrimental to the integrity of the carbon layer than smaller ones. Larger nodules are also less effective insulators compared to smaller nodules. Therefore, carbon layers with large nodules will be less effective insulators.

[0006] Therefore, it would be advantageous to provide an intumescent coating that produces an improved quality (when exposed to heat, such as heat from a fire) of the char layer surface, particularly with fewer and / or smaller nodules. Simultaneously, it is expected that these intumescent coatings will maintain or even improve fire resistance compared to existing coatings, for example, in terms of similar or higher (longer) time to failure (TTF).

[0007] The inventors have now provided a solution to the aforementioned problems. Specifically, it has been surprisingly determined that the use of dicyandiamide in the solvent-based intumescent coating compositions of the present invention (hereinafter sometimes simply referred to as "intumescent coating composition" or "intumescent coating compositions") results in a carbon layer surface with a low number of nodules, particularly a low number of large nodules. In particular, the number and size of nodules are improved (fewer) compared to a comparative composition in which dicyandiamide is not used. Meanwhile, in some embodiments, the improved carbon layer surface quality is accompanied by the maintenance or even increase of the failure time of the intumescent coating formed by the intumescent coating composition. Advantageously, both of these effects can be obtained without the use of melamine or any melamine derivatives. Summary of the Invention

[0008] In one aspect, the present invention provides a solvent-borne intumescent coating composition, comprising: a) At least 5.0 wt% of a polyvinyl ester-based binder and / or a (meth)acrylic-based binder relative to the total weight of the intumescent coating composition. b) Acid-producing agents; c) Carbon donor (carbon source). d) At least 4.0 wt% dicyandiamide relative to the total weight of the intumescent coating composition; The weight ratio of component b):c) is in the range of 2:1 to 4:1.

[0009] In another aspect, the present invention provides a substrate coated with an intumescent coating, preferably a metal substrate, such as steel, the intumescent coating being obtained by: (i) applying an intumescent coating composition as defined above to the substrate, and then (ii) hardening the intumescent coating composition.

[0010] In another aspect, the present invention provides a method for coating a substrate, preferably a metallic substrate such as steel, using an intumescent coating, the method comprising: (i) applying the intumescent coating composition as defined above to the substrate; and then (ii) Harden the intumescent coating composition.

[0011] In another aspect, the present invention provides the use of an intumescent coating composition as defined above for protecting a substrate, preferably a metallic substrate such as steel, from fire and / or heat.

[0012] In another aspect, the present invention provides a method for improving the quality of an intumescent coating produced when the intumescent coating is exposed to fire and / or heat, the method comprising preparing an intumescent coating from a first intumescent coating composition comprising dicyandiamide, preferably an intumescent coating composition as defined above, and wherein the improvement in the quality of the char layer preferably comprises a reduction in the size and / or number of nodules on the surface of the char layer, for example, compared to the surface of a char layer produced by a reference intumescent coating prepared from a second intumescent coating composition, which comprises melamine instead of dicyandiamide, but is otherwise identical to the first intumescent coating composition.

[0013] definition

[0014] In one aspect, this invention relates to an intumescent coating composition. The term "intumescent coating composition" defines a composition that, upon application to a substrate and subsequent drying and / or curing, forms an intumescent coating. Therefore, it should be understood that an intumescent coating prepared from the intumescent coating composition of this invention ideally consists of the components of an intumescent coating composition, except for any solvents and / or water present in the intumescent coating composition, which typically evaporate during the drying / curing process.

[0015] Intumescent coating compositions (and therefore intumescent coatings formed from intumescent coating compositions) include components that ensure expansion. "Intumescent" refers to both charring (coking) and expansion. When exposed to heat from a fire, for example, components in an intumescent coating undergo a chemical reaction to produce gases and a porous carbonaceous layer, which expands into foam as the gases become trapped within the carbonaceous layer. Thus, intumescent coatings form a relatively thick and insulating foam barrier on the surface of a coated substrate exposed to heat from a fire.

[0016] As used herein with respect to intumescent coatings, the term "intumescent" refers to the increase in volume of the coating upon contact with heat from a fire. The depth of the char layer is preferably determined by measuring it using a hydrocone / hydroelectric cone depth gauge (water cone, hydrocone depth gauge, hydraulic cone, depth gauge, hydrocone).

[0017] As used herein, the term "adhesive" refers to a polymer that forms a continuous film on a substrate surface when applied to it. Adhesives can be physically dried / cured, or they can be cured. Physically dried adhesives are preferred.

[0018] The term "expanding agent" is used interchangeably with the term "foaming agent" in this document.

[0019] The term "acid-producing agent" may also be referred to as "acid-producing compound" or "acid catalyst" in this article.

[0020] The terms “(meth)acrylate” or “(meth)acrylic acid” encompass both methacrylate / methacrylic acid and acrylate / acrylic acid.

[0021] The term "dispersion" refers to both particles and droplets (emulsions) dispersed in water / solvent. As used herein, the term "solvent" refers to a solvent other than water, such as an organic solvent.

[0022] Unless otherwise stated, "%" means weight percentage (wt.% or wt%). Similarly, unless otherwise stated, references to "ratio" or "percentage" mean weight ratio or weight percentage. Attached Figure Description

[0023] Figure 1 (Left) An image of the charred surface of the intumescent coating formed by solvent-based intumescent coating composition E8 after a fire test; (Right) An image of the charred surface of the intumescent coating formed by solvent-based comparative intumescent coating composition C6 after a fire test. Detailed Implementation

[0024] This invention relates to an intumescent coating composition that can be used to produce an intumescent coating that exhibits improved char surface quality (e.g., fewer / smaller nodules) when exposed to heat, such as heat from a fire. In some embodiments, the intumescent coating formed from the intumescent coating composition of this invention also retains or even improves fire resistance, for example, as measured by time to failure (TTF). The intumescent coating formed from the intumescent coating composition is intumescent and therefore expands when exposed to heat, such as heat from a fire.

[0025] Component a) – Adhesive

[0026] The intumescent coating composition comprises at least 5.0 wt% of a polyvinyl acetate binder and / or a (meth)acrylic binder relative to the total weight of the intumescent coating composition. Suitable binders of this type will be known to those skilled in the art, and they are commercially available. In one embodiment, the intumescent coating composition comprises a polyvinyl acetate binder but not a (meth)acrylic binder; or comprises a (meth)acrylic binder but not a polyvinyl acetate binder. Alternatively, the intumescent coating composition may comprise both a polyvinyl acetate binder and a (meth)acrylic binder.

[0027] Typically, binders are responsible for the film-forming properties of coating compositions. Binders can also contribute to the structural integrity and mechanical properties of the coating obtained from the coating composition.

[0028] In one embodiment, the amount of binder (component a) relative to the total weight of the intumescent coating composition is in the range of 5.0 to 40.0 wt%, preferably in the range of 7.5 to 35.0 wt%, more preferably in the range of 10.0 to 30.0 wt%. In terms of dry weight%, i.e., ignoring the contribution of any non-solid components in the coating composition, the amount of binder a) in the intumescent coating composition can be in the range of 2.5 to 35.0 wt%, preferably in the range of 4.0 to 30.0 wt%, such as in the range of 5.0 to 25.0 wt%. For example, the intumescent coating composition may contain at least 5.0 dry weight% of binder a), such as at least 7.5 dry weight% of binder a), such as at least 10.0 dry weight% of binder a).

[0029] In one embodiment, a single binder a) is used in the intumescent coating composition. Alternatively, a mixture of different binders a) may be used. When a mixture of binders is used, the amount of binder mentioned above refers to the total amount of binders in the intumescent coating composition, i.e., the sum of the amounts of binders.

[0030] In some embodiments, binder a) is the only binder in the intumescent coating composition. Alternatively, in some embodiments, the intumescent coating composition includes additional binders besides binder a), i.e., binders other than polyvinyl acetate binders and / or (meth)acrylic binders. Examples of suitable additional binder components include paraffins, such as halogenated paraffins, for example, chlorinated paraffins.

[0031] The adhesive can be provided as a dispersion in one or more non-aqueous solvents, such as organic solvents. Alternatively, the adhesive can be provided as a solid and subsequently combined with one or more non-aqueous solvents, such as organic solvents. In one embodiment, the adhesive has a solids content in the range of 30.0 to 70.0 wt%, preferably 35.0 to 65.0 wt%, more preferably 40.0 to 60.0 wt%. In another embodiment, the adhesive can have a solids content up to 100.0 wt%, for example in the range of 80.0 to 100.0 wt%, such as 85.0 to 100.0 wt%, such as 90.0 to 100.0 wt%, such as 95.0 to 100.0 wt%. A combination of a solid adhesive (100 wt% solids content) with a diluent selected from organic solvents (particularly xylene) is particularly preferred. For commercially available adhesives, the solids content of the adhesive can usually be determined by consulting the technical data sheet provided by the adhesive manufacturer.

[0032] Polyvinyl acetate adhesives

[0033] In one embodiment, the intumescent coating composition comprises a polyethylene ester binder. Generally, any known polyethylene ester binder can be used to prepare the intumescent coating composition. Polyvinyl acetate binders are particularly preferred.

[0034] In one embodiment, the polyethylene ester adhesive is a polyethylene ester homopolymer, such as a polyvinyl acetate homopolymer.

[0035] In another embodiment, the polyvinyl ester adhesive is a copolymer derived from vinyl ester monomers such as vinyl acetate and at least one of ethylene, vinyl chloride, different vinyl esters (e.g., vinyl esters of one or more long-chain branched carboxylic acids), di-n-butyl maleate, (meth)acrylic acid, and (meth)acrylate. Copolymers of vinyl ester monomers (especially vinyl acetate) with ethylene and optionally one or more other comonomers are particularly preferred, as are copolymers of vinyl ester monomers (especially vinyl acetate) with vinyl chloride. Copolymers of two or more vinyl ester monomers, such as vinyl acetate and different vinyl esters, optionally with one or more other comonomers (especially ethylene) are also preferred.

[0036] As used herein, the term "copolymer" or "co-polymer" refers to a polymer derived from two or more different comonomers. Therefore, the term includes both polymers strictly derived from two different comonomers (i.e., binary copolymers) and polymers derived from more than two different comonomers (e.g., terpolymers). The term "comonomer" refers to a copolymerizable monomer.

[0037] In another preferred embodiment, the polyvinyl acetate adhesive is a copolymer derived from vinyl acetate and vinyl versatate. The polyvinyl acetate adhesive can also be a terpolymer, such as a terpolymer derived from ethylene, vinyl acetate, and (meth)acrylate. In a preferred embodiment, the adhesive is a terpolymer of vinyl acetate, ethylene, and various vinyl esters (i.e., vinyl esters other than vinyl acetate). Suitable polyvinyl acetate adhesives are commercially available.

[0038] Polyvinyl ester adhesives can be solvent-borne.

[0039] Polyvinyl ester dispersions can be prepared by any suitable known method in the art.

[0040] Suitable commercially available polyvinyl acetate adhesives include Emultex FR 797, Emultex FR 747 and Emultex FR 728 and solvent-based M series from Synthomer; Vinnapas EZ3112, Vinnapas EZ3010, Vinnapas EZ3066 and solvent-based Vinnapas series from Wacker; Mowilith® DC, Mowilith® LDM 1871, Mowilith® LDM 1880 and Mowilith LDM 2301 from Celanese; DowDLP 212 and DowDLP 2141 from Dow; and ENCOR 2341 and ENCOR 2326 from Arkema.

[0041] (meth)acrylic adhesives

[0042] In another embodiment, the intumescent coating composition comprises a (meth)acrylic binder. Any known (meth)acrylic binder can be used to prepare the intumescent coating composition. The (meth)acrylic binder can be used alone or in combination with a polyvinyl acetate binder as described above.

[0043] Typically, adhesives of interest are those prepared using one or more monomers, such as methacrylic acid or methacrylates, including methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 2-hydroxy-1-methylethyl methacrylate, 4-hydroxybutyl methacrylate, and hydroxyisobutyl methacrylate, 2-methoxyethyl methacrylate, 2-ethoxyethyl methacrylate, 2-butoxyethyl methacrylate, 2-(2-ethoxyethoxy)ethyl methacrylate, tetrahydrofurfuryl(meth)acrylate, and isopropylideneglycerol(meth)acrylate. (meth)acrylate), glycerolformal (meth)acrylate, cyclic trimethylolpropane formal (meth)acrylate, hydroxyethyl (meth)acrylate, glycidyl (meth)acrylate and 4-glycidoxybutyl (meth)acrylate, 2-(dimethylamino)ethyl (meth)acrylate, 3-(dimethylamino)propyl (meth)acrylate, 2-(diethylamino)ethyl (meth)acrylate, 2-(diisopropylamino)ethyl (meth)acrylate, 2-(tert-butylamino)ethyl (meth)acrylate and (meth)acrylate.

[0044] (Meth)acrylic binders used in intumescent coating compositions can be binders based on monomers containing two or more polymerizable ethylenically unsaturated bonds. Examples of monomers containing two or more polymerizable ethylenically unsaturated bonds include monomers such as 1,2-ethylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,3-glycerol di(meth)acrylate, methacrylic anhydride, zinc di(meth)acrylate, and trimethylolpropane tri(meth)acrylate.

[0045] (Meth)acrylic monomers containing polyether or polysiloxane groups can also be used.

[0046] The monomers listed above can be combined with other non-(meth)acrylic monomers, such as styrene and acrylonitrile, to prepare the desired polymer. In a preferred embodiment, the (meth)acrylic adhesive is a styrene-(meth)acrylate copolymer.

[0047] (Meth)acrylic adhesives can be physically drying adhesives. (Meth)acrylic adhesives can also be cured by free radical polymerization using azo or peroxide initiators, as described in WO2021 / 180488 Al and WO2005 / 000975 Al. Crosslinking agents such as bifunctional or trifunctional (meth)acrylates or triallyl cyanurates may be present.

[0048] In one embodiment, the (meth)acrylic adhesive can be dissolved in an organic solvent or dispersed in water.

[0049] In one embodiment, the adhesive can be dissolved in an organic solvent. Examples of suitable solvents include xylene, toluene, MIBK, methoxypropanol, MEK, butyl acetate, benzyl alcohol, octylphenol, resorcinol, n-butanol, isobutanol, and isopropanol. (Meth)acrylic acid adhesives dissolved in organic solvents such as xylene are particularly preferred.

[0050] Suitable examples of commercially available (meth)acrylate adhesives include Pliolite AC80, Pliolite AC3H, Plioway Ultra 350LV, Pliolite LV72, Plioway EC1, Plioway ECT, and Pliolite AC5-G from Synthomer. Examples of monomeric (meth)acrylates that can be used in free radical polymerization systems include methyl acrylate (MA) and 2-ethylhexyl acrylate (2-EHA) from BASF, and methyl methacrylate (MMA) from Dow.

[0051] Component b) – Acid-producing agent

[0052] Intumescent coating compositions contain an acid-generating agent (also known as an acid-generating compound). Typically, the acid-generating agent contains a source of phosphoric acid or sulfonic acid that is capable of producing phosphoric acid or sulfonic acid upon exposure to heat, particularly at temperatures above 200°C. Examples of such sources include sodium phosphate, potassium phosphate (e.g., potassium tripolyphosphate), ammonium phosphate (e.g., ammonium polyphosphate (APP), monoammonium phosphate, diammonium phosphate), sodium sulfate, potassium sulfate, ammonium sulfate, magnesium sulfate, or p-toluenesulfonic acid, or any combination thereof.

[0053] Typically, it is the reaction between the acid (produced by the decomposition of an acid-producing agent upon exposure to high temperatures) and a carbon donor compound that leads to the formation of a carbonaceous layer. For example, ammonium polyphosphate, an acid-producing agent, can decompose at approximately 240°C to form ammonia and phosphoric acid. Phosphoric acid can act as an acid in the dehydration reaction of organic polyol compounds such as starch, cellulose, non-polymeric sugars (e.g., glucose, fructose, sucrose, etc.), pentaerythritol, dipentaerythritol, or tripentaerythritol, or any combination thereof, which can act as carbon donor compounds.

[0054] Phosphoric acid can then react with hydroxyl groups to form a thermally unstable phosphate ester, which decomposes to release carbon dioxide and regenerate phosphoric acid. The dehydrated carbon donor and / or binder system then forms a carbonaceous char layer, and the carbon dioxide expands the char layer into a foam.

[0055] In one embodiment, the acid-producing compound comprises a phosphate ester of a polyhydroxy compound, or ammonium phosphate (e.g., APP), or amine phosphate, or any combination thereof.

[0056] A particularly useful acid-producing compound is ammonium polyphosphate (APP), because APP produces phosphoric acid at temperatures typically lower than those of the carbon donor compounds described herein. Therefore, APP produces phosphoric acid that readily participates in char-forming reactions.

[0057] Therefore, in a preferred embodiment, the acid-generating agent is ammonium polyphosphate. Such compounds are typically polyphosphates with POP bonds, which can be represented by the following formula: [NH4PO3] n The average value of n is at least about 10, preferably at least 500, more preferably at least 800, most preferably at least 1000, for example >1000. There is no particular upper limit to the average value of n, but in one embodiment it can be as high as 10000. In one embodiment, the acid-generating agent is coated or uncoated ammonium polyphosphate.

[0058] In another embodiment, the acid-producing compound is boric acid or a source of boric acid that is capable of producing boric acid when exposed to heat, particularly at temperatures above 200°C. The source of boric acid may comprise, for example, borates such as ammonium pentaborate, zinc borate, sodium borate, lithium borate, aluminum borate, magnesium borate, borosilicate compounds, or any combination thereof.

[0059] In one embodiment, the amount of acid-generating agent (component b) is in the range of 10.0 to 50.0 wt%, preferably in the range of 12.0 to 40.0 wt%, more preferably in the range of 15.0 to 35.0 wt%, and most preferably in the range of 18.0 to 30.0 wt%, relative to the total weight of the intumescent coating composition.

[0060] In terms of dry weight percent, the intumescent coating composition may contain an amount of acid-generating agent b) ranging from 12.0 to 75.0 wt%, preferably from 15.0 to 60.0 wt%, more preferably from 20.0 wt% to 50.0 wt%, and most preferably from 25.0 wt% to 45.0 wt%. In a particularly preferred embodiment, the intumescent coating composition may contain an amount of acid-generating agent b) ranging from 30.0 to 40.0 wt% of dry weight.

[0061] When using a mixture of acid-generating agents, the amount of acid-generating agents mentioned above refers to the total amount of acid-generating agents in the intumescent coating composition, that is, the sum of the amounts of acid-generating agents.

[0062] In one embodiment, a single acid-generating agent b) (e.g., ammonium polyphosphate) is used in the intumescent coating composition. Alternatively, the intumescent coating composition may comprise a mixture of acid-generating agents, such as a mixture of ammonium polyphosphate with one or more other acid-generating agents.

[0063] Component c) – Carbon donor

[0064] Intumescent coating compositions contain carbon donors (also known as carbon donor compounds). Typically, the purpose of carbon donors is to enable the formation of carbonaceous carbon layers.

[0065] In one embodiment, the carbon donor is an organic polyhydroxy compound (i.e., an organic polyol) and / or expandable graphite. For example, in one embodiment, the carbon donor compound is selected from the group consisting of: pentaerythritol (i.e., monopentaerythritol), dipentaerythritol, tripentaerythritol, polysaccharides (e.g., starch, cellulose, glycogen, etc.), disaccharides (e.g., sucrose, lactose, maltose, etc.), monosaccharides (e.g., glucose, fructose, galactose, etc.), glycerol, glycols, expandable graphite, or mixtures thereof.

[0066] In a preferred embodiment, the carbon donor is selected from the group consisting of pentaerythritol (i.e., monopentaerythritol), dipentaerythritol, tripentaerythritol, and mixtures thereof. For example, in one embodiment, the carbon donor is pentaerythritol, dipentaerythritol, or a mixture thereof. In a particularly preferred embodiment, the carbon donor is pentaerythritol.

[0067] In one embodiment, the intumescent coating composition comprises at least one solid carbon donor. In another embodiment, the majority (e.g., at least 50 wt%) of the carbon donor in the intumescent coating composition is a solid carbon donor. In a preferred embodiment, at least 60 wt%, such as at least 75 wt%, or at least 90 wt%, such as 60 to 99 wt%, 75 to 98 wt%, or 90 to 95 wt%, of the carbon donor in the intumescent coating composition is a solid carbon donor. In one embodiment, the intumescent coating composition does not contain a liquid carbon donor.

[0068] For the avoidance of doubt, as used herein, the term "solid" means solid at room temperature (25°C) and atmospheric pressure (1 atm), and the term "liquid" means liquid at room temperature (25°C) and atmospheric pressure (1 atm). It should also be understood that the term "carbon donor" excludes those types of components that may be carbon-based but are included in other parts of the composition, such as adhesives (a). Therefore, as used herein, the term "carbon donor" excludes polymerizable film-forming components of intumescent coating compositions, such as adhesives, for example, epoxy resins.

[0069] In one embodiment, the amount of carbon donor (component c) is in the range of 2.5 to 25.0 wt%, preferably in the range of 3.0 to 20.0 wt%, more preferably in the range of 4.0 to 17.5 wt%, and most preferably in the range of 5.0 to 15.0 wt%, relative to the total weight of the intumescent coating composition.

[0070] In terms of dry weight percent, the intumescent coating composition may contain an amount of carbon donor c in the range of 3.5 to 40.0 wt%, preferably in the range of 4.0 to 30.0 wt%, more preferably in the range of 5.0 wt% to 25.0 wt%, and most preferably in the range of 7.0 wt% to 22.5 wt%.

[0071] When using a mixture of carbon donors, the amount of carbon donors mentioned above refers to the total amount of carbon donors in the intumescent coating composition, that is, the sum of the amounts of carbon donors.

[0072] In one embodiment, a single carbon donor, such as pentaerythritol, is used in the intumescent coating composition. Alternatively, the intumescent coating composition may comprise a mixture of carbon donors, such as a mixture of pentaerythritol with one or more other carbon donors.

[0073] Component d) – Dicyandiamide

[0074] The intumescent coating composition contains at least 4.0 wt% dicyandiamide relative to the total weight of the intumescent coating composition.

[0075] Dicyandiamide (also known as cyanoguanidine, 2-cyanoguanidine, DCD, or Dicy) is a nitrile derived from guanidine. It typically exists in one of two tautomers, the structure of which is shown below, although those skilled in the art will understand that a zwitterionic form also exists.

[0076]

[0077] When exposed to heat, such as heat from a fire, as part of an intumescent coating, dicyandiamide typically produces a non-flammable gas, usually nitrogen, which expands the carbon layer derived from the carbon donor, thereby forming a foam-like protective layer on the substrate to be protected. Therefore, dicyandiamide suitably acts as a foaming agent (also called an intumescent agent) in the intumescent coating compositions of the present invention.

[0078] Dicyandiamide used in the intumescent coating compositions of the present invention can be suitably synthesized from one or more precursors, for example by treating cyanamide with an alkali, or can be obtained from commercial sources, typically in powder form. In one embodiment, the intumescent coating composition comprises dicyandiamide in particulate form with a median diameter (D50) in the range of 0.1 to 200 µm, preferably in the range of 0.1 to 100 µm, such as 5 to 50 µm, for example 10 to 40 µm.

[0079] The amount of dicyandiamide in the intumescent coating composition is at least 4.0 wt%. It has been found that amounts below this level are insufficient to improve the surface quality of the char layer while maintaining fire-retardant properties, i.e., insufficient to reduce the number and / or size of nodules formed on the surface of the char layer produced by the intumescent coating composition of the present invention. In one embodiment, the amount of dicyandiamide (component d) relative to the total weight of the intumescent coating composition is in the range of 4.0 to 25.0 wt%, preferably in the range of 5.0 to 20.0 wt%.

[0080] In a particularly preferred embodiment, the amount of dicyandiamide present in the intumescent coating composition is less than 20.0 wt%. This is because it has been found that when using 20.0 wt% or more of dicyandiamide, the surface quality of the char layer is still improved, but the time to failure (TTF) is lower. Therefore, in a preferred embodiment, the amount of dicyandiamide in the intumescent coating composition is in the range of 4.0 to 18.0 wt%, preferably 5.0 to 18.0 wt%, more preferably 6.0 to 18.0 wt%, and most preferably in the range of 8.0 to 16.0 wt%. Within these ranges, the inventors have surprisingly determined that both the surface quality of the char layer and the TTF are acceptable.

[0081] In terms of dry weight percent, the intumescent coating composition may contain an amount of dicyandiamide ranging from 5.5 to 40.0 wt%, preferably from 7.0 to 30.0 wt%, and more preferably from 8.5% to 25.0 wt%.

[0082] In one embodiment, dicyandiamide is the only foaming agent in the intumescent coating composition.

[0083] fiber

[0084] The intumescent coating composition optionally includes fibers. The fibers can be inorganic or organic. Typical inorganic fibers include: carbide fibers, such as boron carbide fibers, silicon carbide fibers, niobium carbide fibers, etc.; nitride fibers, such as silicon nitride fibers; boron-containing fibers, such as boron fibers, boride fibers; silicon-containing fibers, such as silicon fibers, alumina-boron silica fibers, E-glass (alkali-free aluminoborosilicate) fibers, C-glass (alkali-free or low-alkali sodium-calcium-aluminum-borosilicate) fibers, A-glass (base-sodalime-silicate) fibers, S-glass fibers, inorganic glass fibers, quartz fibers, etc. Glass fibers may include E-glass fibers, C-glass fibers, A-glass fibers, S-glass fibers, etc.

[0085] Useful inorganic fibers also include ceramic fibers and basalt fibers. Kevlar (para-aramid fibers) can also be used.

[0086] The preferred organic fiber is carbon fiber.

[0087] Other suitable fibers include mineral fibers. Typically, mineral fibers contain alumina, calcium oxide, iron oxide, magnesium oxide, and / or silicon dioxide.

[0088] In a preferred embodiment, the fiber is a silicate fiber.

[0089] If present, the fiber preferably accounts for at least 0.25 wt% of the intumescent coating composition, preferably at least 0.5 wt%, and more preferably at least 1.0 wt%.

[0090] In some embodiments, the fiber accounts for 0.25 to 20 wt% of the intumescent coating composition, preferably 0.5 to 15 wt%, more preferably 1.0 to 10 wt%.

[0091] In some embodiments, the fiber accounts for 0.3 to 30% dry weight of the intumescent coating composition, preferably 0.6 to 20.0% dry weight, more preferably 1.2 to 15.0% dry weight.

[0092] In some embodiments, the average length of the fiber is 10 to 6000 µm, preferably 50 to 3000 µm, and especially 100 to 1000 µm.

[0093] In a preferred embodiment, fibers of different average lengths are used. Thus, a first fiber group of length X can be combined with a second fiber group of different lengths Y. Using fibers of different average lengths helps to create a fiber network that stabilizes the carbon layer of the expanded composition. The average length difference between fiber groups can be at least 200 µm. For example, a first fiber group of 125 µm can be combined with a second fiber group of 500 µm. A fiber group consists of multiple fibers of substantially the same length.

[0094] In one implementation, three or more groups of fibers with different average lengths are used.

[0095] Ideally, the average length of virtually all fibers should be between 50 and 3000 µm. Fibers with an average length of less than 50 µm are generally not long enough to provide a web-like effect.

[0096] In some embodiments, the melting point of the fiber is above 800°C, preferably above 1000°C, and especially above 1200°C.

[0097] In a preferred embodiment, the intumescent coating composition contains 0.1 to 10 wt%, preferably 0.5 to 8.0 wt%, of an amount such as 1.0 to 5.0 wt% of fiber, for example mineral fiber.

[0098] Pigments and fillers

[0099] Intumescent coating compositions optionally include pigments and / or fillers. Suitable pigments and fillers are well known in the art. Suitable fillers include barium sulfate, titanium dioxide, zinc oxide, aluminum oxide, aluminum hydroxide, magnesium oxide, magnesium hydroxide, carbonates (e.g., dolomite), borates, silica, silicates, heavy metal oxides such as cerium oxide, lanthanum oxide, and zirconium oxide, micronized iron oxide, kaolin, wollastonite, diatomaceous earth, bentonite clay, polymers, and inorganic microspheres such as uncoated or coated hollow and solid glass beads, uncoated or coated hollow and solid ceramic beads, and porous and dense beads of polymer materials. The use of metal oxides, especially transition metal oxides such as titanium dioxide (TiO2), in intumescent coating compositions is particularly preferred.

[0100] Flaky fillers, such as mica, glass flakes, and mica-like iron oxide (MiO), can also be used. Preferred fillers include titanium dioxide, kaolin, and wollastonite.

[0101] When present, the filler preferably comprises 1.0% to 30.0% by weight of the intumescent coating composition, more preferably 2.0% to 20% by weight, and especially 5.0% to 15.0% by weight. In terms of dry weight%, the filler preferably comprises 1.2% to 45% by weight of the intumescent coating composition, more preferably 2.5% to 30.0% by weight, and most preferably 7.0% to 20% by weight. If two or more fillers are used, these percentages refer to the total content of the fillers present. As used herein, the term "filler" does not include fibers, such as mineral fibers.

[0102] As examples of pigments, coloring pigments can be mentioned. Examples of coloring pigments include titanium dioxide, red iron oxide, yellow iron oxide, black iron oxide, carbon black, and organic coloring pigments.

[0103] Fillers and / or pigments can act as carbon layer reinforcing agents. In a preferred embodiment, the intumescent coating composition will contain both mineral fibers and metal oxides.

[0104] In a preferred embodiment, the intumescent coating composition contains 0.1-20.0 wt%, preferably 1.0 to 18.0 wt%, such as 5.0 to 15.0 wt%, of a metal oxide, such as TiO2.

[0105] additive

[0106] In addition to the binders, acid-generating agents, carbon donors, dicyandiamide, and optionally fibers, fillers, and pigments described above, the intumescent coating composition may optionally contain one or more additives conventionally used in intumescent coating compositions. Suitable additives will depend on the binder used and whether the coating composition is solvent-based, water-based, or solvent-free. However, in each case, suitable additives are well known to those skilled in the art.

[0107] Examples of additives that may be present in the intumescent coating compositions of the present invention include rheology modifiers, surfactants, defoamers, pH adjusters, biocides, coalescing agents, and preservatives.

[0108] Suitable rheology modifiers include polyamide waxes, polyethylene waxes, polysaccharides, associative rheology modifiers such as hydrophobically modified alkali-swellable emulsions (HASE) or urethanes (polyurethanes, ethyl urethanes), such as hydrophobically modified ethoxylated urethanes (ethoxylated polyurethanes, ethyl ethoxylated urethanes) (HEUR), clays, cellulose rheology modifiers, acrylic polymer-based rheology modifiers such as alkali-swellable emulsions (ASE thickeners), fumed silica, or mixtures thereof.

[0109] Various surfactants can also be used. This is particularly relevant for water-based coating compositions. A variety of different surfactants may be suitable. Surfactants can be nonionic, anionic, cationic, or amphoteric.

[0110] The coating compositions of the present invention may contain defoamers. Defoamers are sometimes also called foam control agents or defoamers. A variety of defoamers are commercially available and can be used in the coating compositions of the present invention. Representative examples of suitable defoamers include organosiloxanes, polyethers, polyether-modified silicones, mineral oils, and combinations thereof.

[0111] A coalescing agent may optionally be included. In aqueous compositions, the applied wet product is typically non-uniform, unlike solvent-based compositions, which are typically uniform upon application. Therefore, in order to form a film, the polymer binder droplets or particles in the aqueous composition must typically coalesce. Coalescing agents facilitate this process in the aqueous phase. Examples of suitable coalescing agents are 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (Texanol™ ester alcohol), benzyl alcohol, propylene glycol monomethyl ether (PM), propylene glycol propyl ether (PnP), dipropylene glycol n-butyl ether (DPnB), propylene glycol phenyl ether (PPh), tripropylene glycol n-butyl ether (TPnB), ethylene glycol propyl ether (EP), ethylene glycol butyl ether (EB), diacetone alcohol (DAA), and dipropylene glycol methyl ether (DPM).

[0112] In one embodiment, one or more co-solvents are present in the coating composition. As used herein, the term "co-solvent" refers to a solvent that is not the primary solvent present in the intumescent coating composition and is present in an amount of less than 7 wt% relative to the total weight of the coating composition. For example, in one embodiment, the amount of co-solvent is less than 5 wt%, such as less than 3 wt%, or less than 1.0 wt%. When more than one co-solvent is used, the above amount refers to the total amount of co-solvents.

[0113] Suitable cosolvents include polar organic solvents such as acetone, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, diacetone alcohol, dioxane, ethylene glycol, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, dipropylene glycol monomethyl ether, ethylene glycol monopropyl ether, ethylene glycol monohexyl ether, and mixtures thereof.

[0114] To improve or promote the dispersion of optional pigments, fillers, and fibers, wetting / dispersing additives may be incorporated. A variety of dispersants are commercially available and can be used in the coating compositions of this invention. Suitable dispersants include conventional anionic, cationic, nonionic, and amphoteric dispersants, as well as combinations thereof.

[0115] It should be understood that certain components, such as the fibers, fillers, and pigments mentioned above, can also be used to aid in the formation and reinforcement of the char layer and to prevent its degradation (deterioration). These components include solids such as zinc borate, zinc stannate, zinc hydroxystannate, glass flakes, glass spheres, polymer spheres, other fibers (ceramic, mineral, glass / silica-based), aluminum hydroxide oxide, aluminum trihydride, boron phosphate, and fumed silica.

[0116] Anti-corrosion components can also be included in coating compositions. These components can be metal oxides, metal carbonates, talc, feldspar, etc., acting as anti-corrosion materials. Specific anti-corrosion functional pigments include zinc phosphate, zinc oxide, zinc powder, aluminum flakes, and lead oxide. Auxiliary corrosion inhibitors include molybdates, phosphates, tungstates or vanadates, ultrafine titanium dioxide and / or zinc oxide, and / or fillers such as silica, calcined clay, aluminum silicate, talc, barite, or mica.

[0117] The total amount of the various additive components mentioned above depends on the application and cannot be determined indiscriminately, but they are generally included in intumescent coating compositions in total amounts of 0.1 to 50 wt%, such as 0.5 to 40 wt%, preferably 0.5 to 30 wt%.

[0118] In terms of dry weight, the total amount of various additive components in an intumescent coating composition can range from 0.5 to 75 wt%, such as 2 to 60 wt%.

[0119] In a preferred embodiment, the intumescent coating composition comprises 0.1 to 10.0 wt% of one or more additives selected from the group consisting of: plasticizers, rheology modifiers, surfactants, defoamers, pH adjusters, biocides, coalescing agents, and cosolvents.

[0120] diluent

[0121] Intumescent coating compositions typically contain one or more diluents. Such diluents can help dissolve or disperse other components of the coating composition and / or help apply the coating composition to a substrate, for example by ensuring that the viscosity of the coating composition is within a range suitable for forming a layer of the coating composition when applied to a substrate.

[0122] In water-based intumescent coating compositions, the diluent contains water. Since intumescent coating compositions are solvent-borne intumescent coating compositions, the diluent contains solvents other than water, such as organic solvents.

[0123] In water-based intumescent coating compositions, water typically constitutes the majority (e.g., at least 50 wt%, preferably at least 70 wt%, such as at least 90 wt%) of one or more diluents present in the coating composition. In solvent-based intumescent coating compositions, solvents other than water, such as organic solvents, typically constitute the majority (e.g., at least 50 wt%, preferably at least 70 wt%, such as at least 90 wt%) of one or more diluents present in the coating composition. In one embodiment, the diluent may consist substantially of one or more solvents other than water, such as substantially one or more organic solvents.

[0124] There is no particular limitation on the amount of diluent in the intumescent coating composition, and it can be adjusted to obtain the desired viscosity. In one embodiment, the diluent accounts for 5 to 50 wt% of the intumescent coating composition, such as 7.5 to 40 wt%, such as 10 to 30 wt%. For the avoidance of doubt, the amount of diluent does not include the amount of any co-solvents that may be present. Alternatively, any co-solvents present (defined as solvents that are not the main solvent present in the intumescent coating composition and are present in an amount of less than 7 wt% relative to the total weight of the coating composition) are included in the amount of “additives”.

[0125] Solvents other than water, such as organic solvents, are generally unrestricted in their properties, and known solvents with a wide boiling point range can be used. Examples of such solvents include xylene, toluene, methyl isobutyl ketone (MIBK), methoxypropanol, methyl ethyl ketone (MEK), methyl pentyle ketone (MAK), methyl isopentyl ketone (MIAK), n-butyl acetate, tert-butyl acetate, benzyl alcohol, octylphenol, resorcinol, n-butanol, isobutanol, tert-butanol, n-propanol, and isopropanol. Other suitable solvents include polar organic solvents such as acetone, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, diacetone alcohol, dioxane, ethylene glycol, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, dipropylene glycol monomethyl ether, ethylene glycol monopropyl ether, ethylene glycol monohexyl ether, and mixtures thereof. The solvents mentioned above can be used alone or in combination of two or more.

[0126] Intumescent coating compositions

[0127] An intumescent coating composition comprising components a)-d) as described above, and optionally additional components, is a composition capable of forming an intumescent coating when applied to a substrate. Therefore, as used herein, the term "intumescent coating" refers to a coating formed by applying an intumescent coating composition as described above to a substrate surface and allowing the composition to harden. As used herein, the term "coating" includes both partial and complete coatings, i.e., those that cover only a portion of the substrate surface and those that cover the entire surface of the substrate. However, regardless of whether the coating completely or partially covers the substrate, the coating is preferably a continuous coating.

[0128] The intumescent coating composition is solvent-based. For example, in one embodiment, the intumescent coating composition is an intumescent coating composition based on an organic solvent. Preferably, the intumescent coating composition is a one-component intumescent coating composition, i.e., it can be used without adding other components.

[0129] In one embodiment, the intumescent coating composition has a low content of melamine and / or its derivatives. For example, in one embodiment, the intumescent coating composition contains less than 1.0 wt%, preferably less than 0.5 wt%, more preferably less than 0.1 wt% of melamine and / or its derivatives. In one embodiment, the amount of melamine and / or its derivatives is in the range of 0.0 to 1.0 wt%. Preferably, the intumescent coating composition contains no or substantially no melamine and / or its derivatives. For the avoidance of doubt, the term "melamine and / or its derivatives" does not include dicyandiamide.

[0130] The intumescent coating composition preferably has a high solids content. In one embodiment, the solids content of the intumescent coating composition is at least 55 wt%, preferably at least 60 wt%, more preferably at least 65 wt%, and most preferably at least 70 wt%, relative to the total weight of the intumescent coating composition. In some embodiments, the solids content of the intumescent coating composition is as high as 95 wt%, such as up to 90 wt%. A solids content of 70 to 90 wt%, for example 70 to 80 wt%, is preferred. The solids content can be determined according to the methods described herein under the heading "Determination Methods".

[0131] The intumescent coating composition preferably has a low volatile organic compound (VOC) content. In one embodiment, the VOC content is less than 500 g / L, preferably less than 400 g / L, for example, 0 to 400 g / L.

[0132] In one embodiment, the intumescent coating composition has a failure time (time-to-failure) of at least 25 minutes, such as at least 30 minutes, such as at least 40 minutes, such as at least 50 minutes (500°C), as measured according to the method under "Test Method". In one embodiment, the failure time of the intumescent coating composition is up to 120 minutes, such as up to 100 minutes, such as up to 80 minutes.

[0133] In one embodiment, the intumescent coating composition has a pigment volume concentration (PVC) in the range of 40% to 85%, such as 50% to 85%, preferably 60% to 85%, more preferably 65% ​​to 80%. The pigment volume concentration can be determined according to the methods described herein under the heading "Determination Methods".

[0134] The weight ratio of component b):c) (i.e., the weight ratio of the acid-generating agent to the carbon donor in the intumescent coating composition) is in the range of 2:1 to 4:1. In one embodiment, the weight ratio of b):c) is in the range of 2.5:1 to 3.5:1. Preferably, the weight ratio of b):c) is about 3:1. As those skilled in the art will understand, when more than one acid-generating agent and / or more than one carbon donor are present in the intumescent coating composition, the weight ratio b):c) refers to the ratio of the total amount of the acid-generating agent to the total amount of the carbon donor in the composition.

[0135] In one embodiment, the weight ratio of component d):c) (i.e., the weight ratio of dicyandiamide to carbon donor in the intumescent coating composition) is at least 0.5:1, preferably at least 0.75:1, such as at least 1:1. In one embodiment, the weight ratio of d):c) is less than or equal to 4:1, such as less than or equal to 3:1. A range of 0.75:1 to 2.5:1, such as 1:1 to 2:1, is preferred. As those skilled in the art will understand, when more than one carbon donor is present in the intumescent coating composition, the weight ratio d):c) refers to the ratio of the total amount of dicyandiamide to the total amount of carbon donor in the composition.

[0136] In one embodiment, the weight ratio of component b):d) (i.e., the weight ratio of the acid-generating agent to the weight of dicyandiamide in the intumescent coating composition) is less than or equal to 6:1, such as less than or equal to 5:1, such as less than or equal to 4:1. For example, the ratio of b):d) can be in the range of 1:1 to 6:1, such as in the range of 1:1 to 5:1, such as in the range of 1:1 to 4:1, such as in the range of 1.5:1 to 3:1. As those skilled in the art will understand, when more than one acid-generating agent is present in the intumescent coating composition, the weight ratio b):d) refers to the ratio of the total amount of the acid-generating agent to the total amount of dicyandiamide in the composition.

[0137] In one embodiment, the total amount of acid-generating agent (including any APP), foaming agent (including any melamine), and pigment (including any TiO2 and / or carbon black) relative to the total weight of the intumescent coating composition is less than 55 wt%, such as 10 to 55 wt%, such as 15 to 52 wt%, such as 20 to 50 wt%.

[0138] In a preferred embodiment, the intumescent coating composition of the present invention comprises: a) 5.0 to 40.0 wt%, for example 10.0 to 30.0 wt%, of polyvinyl acetate binders and / or (meth)acrylic binders relative to the total weight of the intumescent coating composition; b) 10.0 to 50.0 wt%, for example 18.0 to 30.0 wt% ammonium polyphosphate; c) 2.5 to 25.0 wt%, for example 5.0 to 15.0 wt% of pentaerythritol; d) 4.0 to 25.0 wt%, for example 8.0 to 16.0 wt% of dicyandiamide; e) 0.0 to 20.0 wt%, for example 5.0 to 15.0 wt%, of at least one metal oxide, preferably TiO2; f) 0.0 to 10.0 wt%, for example 1.0 to 5.0 wt% of fibers; and g) 0.0 to 10.0 wt%, for example 1.0 to 5.0 wt%, of one or more additives selected from the group consisting of: plasticizers, rheology modifiers, surfactants, defoamers, pH adjusters, biocides, coalescing agents and cosolvents.

[0139] Preparation of coating composition

[0140] Intumescent coating compositions can be prepared using any suitable technique commonly used in the art. Therefore, various components can be mixed together using high-speed dispersers, ball mills, bead mills, three-roll mills, in-line mixers, etc.

[0141] Typically, intumescent coating compositions are supplied as single-component compositions, meaning they are ready to use. Intumescent coating compositions can be stored before use. Suitable storage conditions for intumescent coating compositions include temperatures of 0-40°C (solvent-based).

[0142] Application of coating composition

[0143] The intumescent coating composition can be applied to a substrate, such as a metallic substrate like steel. Optionally, the substrate may have already been coated, for example, with a primer layer. Thus, the resulting substrate coated with the intumescent coating composition as defined above constitutes another aspect of the invention. Optionally, the intumescent coating composition on the substrate has been cured to form an intumescent coating.

[0144] In another aspect, the present invention relates to a substrate coated with an intumescent coating, preferably a metallic substrate such as steel. The intumescent coating is obtained by: (i) applying an intumescent coating composition as defined above to the substrate, and then (ii) curing the intumescent coating composition. It should be understood that the intumescent coating ideally consists of the same components as the intumescent coating composition, except for any volatile components, such as water / solvent, lost through evaporation during the curing process.

[0145] In another aspect, the present invention relates to a method for coating a substrate, preferably a metallic substrate such as steel, using an intumescent coating, the method comprising: (i) Applying the intumescent coating composition as defined above to a substrate; and then (ii) To harden the intumescent coating composition.

[0146] Intumescent coating compositions can be applied to a substrate, preferably a steel substrate, using known standard application methods, such as spraying, for example, conventional air spraying or using airless or mixed-air spraying equipment, or manually, for example, by means of a brush or roller. Application typically results in the formation of a layer of the coating composition. Multiple layers of the coating composition can be applied to establish layer thickness.

[0147] Curing of a coating composition may involve the loss of volatile components from the coating composition (i.e., drying) and / or a curing reaction within the coating composition. Curing a coating composition may therefore involve passively curing the coating composition, or alternatively, promoting curing, for example by applying heat and / or drying means, such as air.

[0148] In another aspect, the present invention provides an intumescent coating that is preferably obtainable from an intumescent coating composition as defined above.

[0149] film thickness

[0150] Intumescent coating compositions are typically applied with a high dry film thickness to ensure good fire protection. The applied film thickness may vary depending on the properties of the substrate being coated and the intended fire exposure scenario.

[0151] The dry film thickness of the intumescent layer is preferably 100 µm–10000 µm, more preferably 150 µm–7500 µm, and even more preferably 200 µm to 5000 µm. It should be understood that film thickness is a function of the substrate to which the coating composition is applied. Different substrate thicknesses and geometries may require different thicknesses. Substrates may be subject to different minimum fire resistance test requirements and therefore require different levels of protection. Selecting an appropriate film thickness is within the capabilities of those skilled in the art.

[0152] The intumescent coating composition can be applied multiple times to achieve the appropriate dry film thickness.

[0153] The substrate is typically a metal substrate, such as steel. However, generally, any substrate that requires fire protection can be used.

[0154] In one embodiment, the intumescent coating composition is applied directly to the surface of a substrate, i.e., directly to the substrate, such as directly to metal. However, in a preferred embodiment, the intumescent coating composition is applied indirectly, for example, to a primer layer disposed on a base substrate. Suitable primer layers are known in the art and are typically formed of epoxy resins, although other options may be used. The primer layer preferably contains at least 20 wt% epoxy resin, more preferably at least 25 wt% epoxy resin.

[0155] Examples of suitable primer layers include coatings based on epoxy (epoxy resin), polyurethane, acrylic, alkyd, vinyl, and chlorinated rubber. Preferred primer layers are epoxy-based primers or zinc-rich epoxy-based primers. In one embodiment, the primer is a shop primer.

[0156] In another embodiment, the primer layer is a polysiloxane sol primer such as that described in US2014 / 0106176.

[0157] When present, the dry film thickness of the primer is ideally in the range of 15 to 250 µm. Therefore, in one embodiment, the present invention provides a substrate coated in this order with a primer layer and an intumescent coating as defined above. Optionally, a topcoat layer is disposed on top of the intumescent coating. Typically, any topcoat layer conventionally used in the art can be applied to the intumescent coating. Suitable topcoats are known to those skilled in the art.

[0158] application

[0159] The intumescent coating compositions of the present invention can be used to form intumescent coatings that protect substrates, such as steel substrates, from damage caused by extreme heat, such as heat generated by a fire. Therefore, in one aspect, the present invention relates to the use of intumescent coating compositions as defined above for protecting substrates, preferably metallic substrates such as steel, from fire and / or heat. This use may include preparing an intumescent coating composition as defined above and subsequently applying the coating composition directly or indirectly (e.g., on a primer layer) to the substrate to be protected. This use may also include curing the composition after application to the substrate.

[0160] In another aspect, the present invention relates to a method for improving the quality of an intumescent coating produced when the intumescent coating is exposed to fire and / or heat, the method comprising forming an intumescent coating from a (first) intumescent coating composition comprising dicyandiamide, preferably an intumescent coating composition as defined above. The improvement in the quality of the char layer preferably comprises a reduction in the size and / or number of nodules on the surface of the char layer, for example, compared to the surface of a char layer produced by a reference intumescent coating prepared from a second intumescent coating composition, which comprises melamine instead of dicyandiamide, but is otherwise identical to the first intumescent coating composition.

[0161] Determination methods

[0162] Solid content

[0163] The solids content of the adhesive or intumescent coating composition is calculated according to ASTM D5201 – 05a(2020). The solids content can be expressed as a weight percentage (wt%) or a volume percentage (vol%) relative to the total weight or total volume of the adhesive / composition.

[0164] Volatile organic compound (VOC) content

[0165] The VOC content of the intumescent coating composition was measured according to US EPA Method 24.

[0166] Pigment volume concentration (PVC)

[0167] The pigment volume concentration (PVC) of the composition is calculated using the formula PVC = ((Vp + Vf) / (Vp+Vf+Vb)). 100 is determined by calculation. Where Vp is the volume of pigment, Vf is the volume of filler including glass beads, and Vb is the volume of binder. It is expressed as a percentage (%).

[0168] Fire resistance test of intumescent coating compositions

[0169] For fire resistance testing, the coating composition was applied to a carbon steel plate sandblasted to SSPC SP10 (300 x 300 x 6 mm) and primed with MUKI EPS from Jotun to a dry film thickness (DFT) of approximately 30 µm. An intumescent coating composition was applied to a wet film thickness corresponding to 1 mm DFT. The coating was dried at 23°C and 50% RH for at least 14 days prior to fire curve testing according to EN1363-1. The furnace temperature was measured and controlled using four bare-wire K-type nichrome-nichrome-aluminum thermocouples placed inside the furnace and close to the sample, according to internal testing procedures. The furnace pressure was continuously monitored by a micro-manometer and maintained at approximately 10 Pa during the test. The time to failure (TTF) was recorded as the average of two K-type nichrome-nichrome-aluminum thermocouples placed according to EN16623. Fire resistance testing was conducted until the average steel temperature of the test sample reached the set failure temperature of 500°C. The time to reach this temperature was recorded in minutes and reported as the TTF.

[0170] Carbon layer surface quality

[0171] The quality of the char layer surface resulting from the above fire resistance test is evaluated. The evaluation involves assessing the size and density (number density) of the nodules on a scale of 1-4. The following descriptors are used to assign a char layer surface quality score to each exemplary intumescent coating:

[0172] A rating of 1 or 2 is considered acceptable, while a rating of 3 or 4 is considered unacceptable.

[0173] Example

[0174] Solvent-based intumescent coating compositions according to the present invention were prepared and their fire resistance was tested according to the methods described under the heading "Determination Methods".

[0175] Solvent-based intumescent coating compositions

[0176] The following table (Table 1) lists the components in the exemplary solvent-based intumescent coating compositions of the present invention (E8-E12) and comparative invention (C6-C7).

[0177] Table 1:

[0178] The components in Table 1 were mixed together using a high-speed disperser in the proportions shown in Table 2 to form the solvent-based intumescent coating compositions of the present invention (E8-E12) and comparative (C6-C7). The coating compositions were subjected to fire resistance testing as described under the heading “Determination Methods” herein. The performance of the coating compositions and the results of the fire resistance tests (char surface quality score and TTF) are also reported in Table 2. Images of the char surface of Examples E8 (left) and C6 (right) are shown. Figure 1 middle.

[0179] Table 2:

[0180] Compared to C6 (using melamine as a blowing agent) and C7 (without a blowing agent), E8-E12 (using dicyandiamide as a blowing agent) showed a significant reduction in the number and size of nodules on the carbon layer surface. The TTF of E8-12 was slightly affected compared to C6, but was still significantly higher than that of C7. The TTF of E10 was particularly good.

[0181] Therefore, the above embodiments demonstrate that using dicyandiamide instead of melamine alone as a foaming agent in the solvent-based intumescent coating composition of the present invention results in a significant improvement in the quality of the char layer produced by the resulting intumescent coating, particularly in terms of lower nodule size and density on the char layer surface. Furthermore, the intumescent coating of the present invention exhibits a significantly improved TTF compared to coatings completely free of foaming agents, and only a slight impact on TTF compared to coatings containing only melamine as a foaming agent.

Claims

1. A solvent-based intumescent coating composition, comprising: a) At least 5.0 wt% of polyvinyl acetate binder and / or (meth)acrylic binder relative to the total weight of the intumescent coating composition; b) Acid-producing agents; c) Carbon donor; d) At least 4.0 wt% dicyandiamide relative to the total weight of the intumescent coating composition; The weight ratio of component b):c) is in the range of 2:1 to 4:

1.

2. The solvent-based intumescent coating composition according to claim 1, wherein, The amount of component a) relative to the total weight of the intumescent coating composition is in the range of 5.0 to 40.0 wt%, preferably in the range of 7.5 to 35.0 wt%, and more preferably in the range of 10.0 to 30.0 wt%.

3. The solvent-based intumescent coating composition according to claim 1 or 2, wherein, The amount of component b) relative to the total weight of the intumescent coating composition is in the range of 10.0 to 50.0 wt%, preferably in the range of 12.0 to 40.0 wt%, more preferably in the range of 15.0 to 35.0 wt%, and most preferably in the range of 18.0 to 30.0 wt%.

4. The solvent-based intumescent coating composition according to any one of the preceding claims, wherein, The amount of component c) relative to the total weight of the intumescent coating composition is in the range of 2.5 to 25.0 wt%, preferably in the range of 3.0 to 20.0 wt%, more preferably in the range of 4.0 to 17.5 wt%, and most preferably in the range of 5.0 to 15.0 wt%.

5. The solvent-based intumescent coating composition according to any one of the preceding claims, wherein, The amount of component d) relative to the total weight of the intumescent coating composition is in the range of 4.0 to 25.0 wt%, preferably in the range of 5.0 to 20.0 wt%, more preferably in the range of 6.0 to 18.0 wt%, and most preferably in the range of 8.0 to 16.0 wt%.

6. The solvent-based intumescent coating composition according to any one of the preceding claims, wherein, The weight ratio of component d):c) is at least 0.5:1, preferably at least 1:1, such as in the range of 1:1 to 4:1, such as 1:1 to 3:

1.

7. The solvent-based intumescent coating composition according to any one of the preceding claims, wherein, The weight ratio of component b):d) is less than or equal to 6:1, such as less than or equal to 5:1, such as less than or equal to 4:1, such as in the range of 1:1 to 4:1, such as in the range of 1:1 to 3:

1.

8. The solvent-based intumescent coating composition according to any one of the preceding claims, wherein, The acid-generating agent is ammonium polyphosphate, preferably ammonium polyphosphate represented by the following formula: [NH4PO3] n Wherein, the average value of n is at least about 10, preferably at least 500, more preferably at least 800, and most preferably at least 1000.

9. The solvent-based intumescent coating composition according to any one of the preceding claims, wherein, The carbon donor is selected from the group consisting of pentaerythritol, dipentaerythritol, tripentaerythritol and mixtures thereof, preferably pentaerythritol.

10. The solvent-based intumescent coating composition according to any one of the preceding claims, wherein, The intumescent coating composition contains less than 1.0 wt%, preferably less than 0.5 wt%, more preferably less than 0.1 wt% of melamine and / or its derivatives.

11. The solvent-based intumescent coating composition according to any one of the preceding claims, wherein, The intumescent coating composition is free of melamine and / or its derivatives.

12. The solvent-based intumescent coating composition according to any one of the preceding claims, comprising: a) 5.0 to 40.0 wt% of polyvinyl acetate binders and / or (meth)acrylic binders relative to the total weight of the intumescent coating composition; b) 10.0 to 50.0 wt% ammonium polyphosphate; c) 2.5 to 25.0 wt% pentaerythritol; d) 4.0 to 25.0 wt% dicyandiamide; e) 0.0 to 20.0 wt% of at least one metal oxide, preferably TiO2; f) 0.0 to 10.0 wt% of fibers; and g) 0.0 to 10.0 wt% of additives selected from the group consisting of plasticizers, rheology modifiers, surfactants, defoamers, pH adjusters, biocides, coalescing agents, cosolvents and mixtures thereof.

13. The solvent-based intumescent coating composition according to any one of the preceding claims, wherein, The intumescent coating composition has a solids content of at least 55 wt%, preferably at least 60 wt%, more preferably at least 65 wt%, and most preferably at least 70 wt% relative to the total weight of the intumescent coating composition.

14. The solvent-based intumescent coating composition according to any one of the preceding claims further comprises at least one metal oxide, preferably a transition metal oxide, especially titanium dioxide (TiO2).

15. The solvent-based intumescent coating composition according to claim 14, wherein, The intumescent coating composition contains less than 1.0 wt%, preferably less than 0.5 wt%, more preferably less than 0.1 wt% of melamine and / or its derivatives, or does not contain melamine and / or its derivatives.

16. The solvent-based intumescent coating composition according to any one of the preceding claims has a pigment volume concentration (PVC) in the range of 40% to 85%, such as 50% to 85%, preferably 60% to 85%, more preferably 65% ​​to 80%.

17. The solvent-based intumescent coating composition according to any one of the preceding claims, wherein the solvent is an organic solvent.

18. A substrate coated with an intumescent coating, preferably a metal substrate, such as steel, wherein the intumescent coating is obtained by: (i) applying a solvent-based intumescent coating composition according to any one of the preceding claims to the substrate, and then (ii) curing the intumescent coating composition.

19. A method for coating a substrate, preferably a metallic substrate such as steel, using an intumescent coating, the method comprising: (i) Applying the solvent-based intumescent coating composition according to any one of claims 1 to 17 to the substrate; And then (ii) Harden the intumescent coating composition.

20. The solvent-based intumescent coating composition according to any one of claims 1 to 17 is used for protecting a substrate, preferably a metallic substrate such as steel, from fire and / or heat.

21. A method for improving the quality of a char layer produced by an intumescent coating when the intumescent coating is exposed to fire and / or heat, the method comprising preparing the intumescent coating from a first intumescent coating composition comprising dicyandiamide, preferably an intumescent coating composition according to any one of claims 1 to 17; wherein, The improvement in the quality of the carbon layer preferably includes a reduction in the size and / or number of nodules on the surface of the carbon layer, for example, compared to the surface of a carbon layer produced by a reference intumescent coating prepared from a second intumescent coating composition, which contains melamine instead of dicyandiamide, but is otherwise identical to the first intumescent coating composition.

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