coating

Abstract

A method for applying an intumescent coating system to a substrate, comprising: (I) applying an intumescent coating composition to a substrate, the intumescent coating composition comprising i. an epoxy-based adhesive; ii. a curing agent; iii. an intumescent agent; iv. an acid-generating compound; and v. at least 5 wt.% of water; and curing the composition to form an intumescent coating; (II) applying a topcoat composition to the cured or partially cured intumescent coating to form a topcoat, the topcoat composition comprising an acrylic adhesive, a polyurethane adhesive or a silicone adhesive and at least 10 wt.% of water.

Description

Technical Field

[0001] The present invention relates to an intumescent coating system comprising an intumescent coating layer comprising an epoxy adhesive and a curing agent for the adhesive and a top coat layer comprising an acrylic adhesive, a polyurethane adhesive or a silicone adhesive obtained from an aqueous starting material. The present invention also relates to a process for preparing such an intumescent coating system.

[0002] The intumescent coating system has excellent durability while maintaining suitable char forming and insulating properties required of an intumescent coating system. The present invention also relates to a method for applying such an intumescent coating system to a substrate. The present invention also relates to a substrate coated with the cured intumescent coating system. Background Art

[0003] In order to protect substrates from fire, it is well known to protect the substrates with intumescent coatings. Waterborne intumescent coatings are an environmentally friendly alternative to solventborne intumescent coatings. The benefit of using waterborne intumescent coating compositions instead of solventborne intumescent coating compositions is that water can be used as a solvent during spray application and as a cleaning solvent. This is beneficial from both an environmental and health and safety perspective.

[0004] Solvent-free intumescent coatings are also known, but are generally difficult to apply due to their viscosity.

[0005] Intumescent coatings are sometimes applied as part of a coating system comprising an intumescent coating and a topcoat. The substrate may also be protected by a primer layer beneath the intumescent coating. Unless the topcoat is also applied with water, the value of designing a waterborne intumescent coating is reduced. From an environmental and health and safety perspective, it is desirable for both layers to be made of waterborne coating compositions.

[0006] Commercially available waterborne intumescent coatings are typically based on vinyl acetate-based binders. A common challenge in the coatings industry is the incompatibility between waterborne intumescent coatings and waterborne topcoats. This causes the wet waterborne topcoat film to separate from the underlying layer and form cracks in the dry film. To avoid this problem, solventborne topcoats are often used instead.

[0007] The inventors have surprisingly found that if a waterborne intumescent coating based on an epoxy-based binder is used, there is no incompatibility with certain waterborne topcoats. Thus, an intumescent coating system can be prepared in which both the intumescent layer and the topcoat are formed from a waterborne coating composition.

[0008] Furthermore, we have surprisingly found that epoxy-based waterborne intumescent coatings have several other advantages over waterborne intumescent coatings based on vinyl acetate-based binders, such as improved mechanical strength and improved exterior durability.

[0009] Waterborne intumescent epoxy coatings are known. EP-A-3339385 describes a waterborne epoxy coating for external inorganic fire protection. The epoxy resin may be a bisphenol A or F resin optionally with a reactive diluent. There is no mention of using this coating in combination with a waterborne topcoat.

[0010] US20190315911 describes an intumescent coating system comprising at least a flame retardant layer and an intumescent layer. Optionally, an anti-weathering composition can be applied to the intumescent composition. The anti-weathering composition is a vinyl-polysiloxane. The flame retardant layer and the intumescent layer contain an epoxy adhesive and water, but the anti-weathering composition does not contain any water.

[0011] CN 102492323 describes a fire retardant coating system with overall low coating thickness, good fire retardant performance and good decorative effect, wherein the intermediate intumescent coating is based on melamine-formaldehyde and does not contain epoxy resin.

[0012] Compatibility between waterborne intumescent coatings and waterborne topcoats is a common problem in the industry. Summary of the invention

[0013] Thus, viewed from one aspect, the present invention provides a method for applying an intumescent coating system to a substrate comprising:

[0014] (I) applying to a substrate an intumescent coating composition comprising:

[0015] i. Epoxy adhesive (epoxy-based binder);

[0016] ii. Curing agent;

[0017] iii. expansion agent;

[0018] iv. an acid generating compound; and

[0019] v. at least 5wt.% water;

[0020] and curing the composition to form an intumescent coating;

[0021] (II) applying a top coat composition to the cured or partially cured intumescent coating to form a top coat, the top coat composition comprising an acrylic-based binder, a polyurethane binder or a silicone binder and at least 10 wt.% of water.

[0022] Viewed from another aspect, the invention provides an intumescent coating system obtainable by the process as defined above. Such an intumescent coating system may comprise:

[0023] B) Intumescent coating;

[0024] C) top coating;

[0025] Wherein the intumescent coating comprises:

[0026] i. Epoxy adhesive;

[0027] ii. Curing agent;

[0028] iii. expansion agents; and

[0029] iv. acid-generating compounds;

[0030] The top coating layer comprises an acrylic adhesive, a polyurethane adhesive or a silicone adhesive.

[0031] Viewed from another aspect, the invention provides a method for applying an intumescent coating system to a substrate comprising:

[0032] (I) applying a primer layer comprising an epoxy-based adhesive or a vinyl-based adhesive (vinyl-based binder) to a substrate to form a primer layer on the substrate;

[0033] (II) applying to the primer layer an intumescent coating composition comprising:

[0034] i. Epoxy adhesive;

[0035] ii. Curing agent;

[0036] iii. expansion agent;

[0037] iv. an acid generating compound; and

[0038] v. at least 5wt.% water;

[0039] and curing the composition to form an intumescent coating;

[0040] (III) applying a top coating composition to the cured or partially cured intumescent coating to form a top coating, the top coating composition comprising an acrylic adhesive, a polyurethane adhesive or a silicone adhesive and at least 10 wt. % of water.

[0041] Viewed from another aspect, the present invention provides an intumescent coating system, the intumescent coating system comprising an intumescent coating system comprising:

[0042] A) Primer layer;

[0043] B) Intumescent coating;

[0044] C) top coating;

[0045] The primer layer comprises an epoxy adhesive or a vinyl adhesive;

[0046] Wherein the intumescent coating comprises:

[0047] I. Epoxy adhesives;

[0048] ii. Curing agent;

[0049] iii. expansion agents; and

[0050] iv. acid-generating compounds;

[0051] The top coating layer comprises an acrylic adhesive, a polyurethane adhesive or a silicone adhesive.

[0052] In one embodiment, the intumescent coating comprises the cured product of its components.

[0053] Viewed from another aspect the invention provides a substrate coated with an intumescent coating system as hereinbefore defined.

[0054] Viewed from another aspect the invention provides a substrate coated with a cured intumescent coating system as hereinbefore defined.

[0055] Viewed from another aspect the invention provides the use of an intumescent coating system as hereinbefore defined to coat a substrate.

[0056] In one embodiment, the substrate to which the intumescent coating composition is applied is provided with a primer layer.

[0057] definition

[0058] The present invention relates to an intumescent coating system. The term intumescent coating system defines a multilayer coating comprising at least an intumescent coating and a topcoat directly thereon. Directly below the intumescent coating there may also be at least one primer layer. Thus, the intumescent coating system of the present invention may comprise 2 or 3 layers or more. Multiple coats of a particular composition may be required to develop a suitable film thickness. We regard the application of multiple coats of the same composition as forming a single layer in the intumescent coating system.

[0059] The term intumescent coating composition defines a composition for preparing an intumescent coating. Such an intumescent coating composition may itself be formed by the combination of a first composition (A) and a second composition (B) as further defined below. To prevent premature curing, the intumescent coating composition may be provided in two parts, a first composition (A) comprising an epoxy binder and a second composition (B) comprising a curing agent. The other components of the intumescent coating composition may be present in component (A) or (B), provided that any component present in component (A) does not react with any other component in component (A), and any component present in component (B) does not react with any other component in component (B).

[0060] The intumescent coating composition comprises a binder system defined as a combination of one or more binder resins and a curing agent. If present, reactive diluents and flame retardants are also considered part of the binder system.

[0061] The intumescent coating composition also contains components that ensure expansion. "Intumescence" refers to carbonization (char) and expansion. For example, when exposed to heat from a fire, the components in the intumescent coating chemically react to produce gases and a cellular carbonaceous char that expands into foam as the gases are trapped in the char. Thus, the intumescent coating forms a relatively thick and insulating foam barrier on the surface of the coated substrate exposed to fire and / or relatively high heat.

[0062] The term expansion agent is used interchangeably with the term blowing agent.

[0063] The term acid generating compound may also be referred to herein as an acid catalyst.

[0064] The term (meth)acrylate includes both methacrylates and acrylates.

[0065] The term topcoat composition defines the composition used to prepare the topcoat. DETAILED DESCRIPTION

[0066] The present invention relates to an intumescent coating system for a substrate, such as a metal substrate, a composite material or a cellulosic substrate, preferably a steel substrate. The substrate may be present on any object on which the coating of the present invention may be useful.

[0067] The substrate may be in structures such as residences, hotels, shopping malls, museums, airports, commercial offices, and the like.

[0068] The substrate may be provided with a conventional anti-corrosion primer coating to which the intumescent coating adheres. Examples of suitable primer layers are coatings based on epoxy resins, modified epoxy resins (such as modified with polyvinyl butyral), polyurethane, acrylic (acrylic), vinyl (vinyl) and chlorinated rubber. Preferably, the primer layer is an epoxy-based primer or a zinc-rich epoxy-based primer. The dry film thickness of the primer is ideally in the range of 15 to 500 microns.

[0069] The intumescent coating composition may also be applied directly to a substrate, for example directly to metal.

[0070] The intumescent coating is overcoated with a top coat layer. The top coat layer can provide the desired color to the substrate and enhance the durability of the intumescent coating system. A clear top coat may also be suitable.

[0071] The top coating used may comprise an acrylic adhesive, a polyurethane adhesive or a silicone adhesive. Preferably, the top coating comprises an acrylic adhesive. The thickness of the top coating may vary from 15 microns to 250 microns. Preferably, the thickness should be in the range of 25 microns to 75 microns, because a top coating with too high a thickness may inhibit the expansion reaction. The top coating composition may be applied in multiple applications to obtain a suitable dry film thickness.

[0072] The intumescent coating composition is applied at a high dry film thickness to ensure good fire protection. The dry film thickness of the intumescent coating is preferably from 0.1 to 8.0 mm. The intumescent coating composition may be applied in multiple applications to obtain a suitable dry film thickness.

[0073] Intumescent coatings are designed to protect substrates to a critical core temperature in the range of 200-700°C, depending on the nature of the substrate, the degree of loading and the special requirements of the particular structure being protected. The critical core temperature is generally defined as the temperature at which a particular substrate has lost its load-bearing capacity to such an extent that the structure is at imminent risk of critical collapse.

[0074] Intumescent coating composition

[0075] The intumescent coating is prepared by applying an intumescent coating composition to a substrate. The intumescent coating composition comprises a binder system based on at least one epoxy binder which is cured using at least one curing agent. The intumescent coating composition also comprises an intumescent component and may comprise conventional intumescent coating components such as pigments, fillers and standard additives. It must be waterborne.

[0076] The intumescent coating composition preferably comprises a component (A) comprising at least one epoxy binder; and a component (B) comprising at least one curing agent.

[0077] Combinations with epoxy adhesives are also possible. The intumescent coating composition is typically provided in kit form, and shortly before applying the intumescent coating composition to a substrate, a first composition comprising an epoxy adhesive is mixed with a second composition comprising a curing agent to form the intumescent coating composition. After application, the intumescent coating composition is subsequently cured on the substrate to form an intumescent coating.

[0078] In one embodiment, the binder system of the intumescent coating composition comprises at least one liquid epoxy binder. The term liquid refers to the state of the epoxy binder at room temperature and 23°C, at a pressure of 1 atm.

[0079] Preferably, the intumescent coating composition does not contain any organic solvents and therefore has a low content of volatile organic compounds (VOCs).

[0080] The intumescent coating composition of the present invention preferably contains very low organic solvent content, such as less than 1.0 wt% organic solvent, especially less than 0.5 wt% organic solvent, more especially no organic solvent.Ideally, no organic solvent is present in the intumescent coating composition at all.

[0081] However, the intumescent coating composition of the present invention must be waterborne.Preferably, the intumescent coating composition has a volume solids content of at least 50%, such as at least 55%, for example from 55 to 60%.

[0082] The intumescent coating composition of the invention may comprise at least 5 wt% water, such as at least 8 wt% water, for example 10 to 50 wt% water, such as 10 to 30 wt% water.

[0083] The VOC content of the intumescent coating composition is preferably less than 100 g / L, more preferably less than 50 g / L, and most preferably less than 25 g / L. In some embodiments, the VOC content may be 10 g / L or less. In this aspect, the volatile organic compound comprises benzyl alcohol.

[0084] The intumescent coating composition of the present invention preferably has a pot life of at least 1 hour, such as 1 to 3 hours, for example 1.5 to 2.5 hours. Pot life refers to the time during which the intumescent coating composition can still be applied to a substrate after mixing of the first and second components. A pot life of less than 30 minutes is commercially challenging given the time taken to coat large objects.

[0085] The viscosity of the intumescent coating composition measured immediately after the two components are combined should be high in order to ensure the application of thick layers with a high amount of intumescent pigments and thus to ensure good fire protection.

[0086] The viscosity measured on a Brookfield DV-II with spindle 6 at 10 rpm at 23°C may range from 10,000 to 100,000 cP for both the A and B components. The intumescent coating systems of the present invention are most particularly relevant to maintaining exterior durability without any reduction in passive fire performance as in the case of waterborne systems.

[0087] The intumescent coating composition of the present invention adheres well to both the substrate or the primer layer on the substrate and the topcoat layer.

[0088] The components of the intumescent coating composition will now be described in more detail. These components may be present in any component of the kit for preparing the intumescent coating composition, provided that the curing agent is kept separate from any other components of the intumescent coating composition with which it may react during storage.

[0089] Intumescent component of coating composition

[0090] The intumescent coating composition of the present invention comprises a binder system (comprising at least an epoxy binder and a curing agent) and an intumescent coating component. These include an acid generator, which typically thermally decomposes at elevated temperatures (e.g., greater than 200° C.) and produces an acid that reacts with a carbon donor compound to produce a carbonaceous char. The intumescent component also includes an expansion agent (foaming agent, expansion agent, expansion agent), which decomposes at elevated temperatures (e.g., greater than 200° C.) and produces a gas that expands the volume of the carbonaceous char and produces a carbonaceous foam.

[0091] The intumescent coating composition of the present invention may comprise specific carbon donor compounds acting as charring agents.

[0092] In a preferred embodiment, the intumescent coating composition comprises a specific carbon donor compound as detailed below.The binder system comprising at least an epoxy binder and a curing agent may also provide a carbon source which is converted to char in a fire.

[0093] For example, when the intumescent coating is exposed to fire or heat and thus the temperature of the intumescent coating exceeds 200°C, the acid generator decomposes to provide acid. The carbon donor compound reacts with the acid to form a carbonaceous char. For example, ammonium polyphosphate (AMPP) acid generator decomposes at about 240°C to form ammonia and phosphoric acid. Phosphoric acid can be used as an acid for the dehydration reaction of an organic polyol compound such as starch, cellulose, non-polymeric sugars (e.g., glucose, fructose, sucrose, etc.), pentaerythritol, dipentaerythritol, or tripentaerythritol, or any combination thereof, which is used as a carbon donor compound.

[0094] Phosphoric acid reacts with hydroxyl groups to form thermally unstable phosphate esters, which decompose to release carbon dioxide and regenerate phosphoric acid. The dehydrated carbon donor and / or binder system forms a carbonaceous char, and the carbon dioxide expands the char into a foam.

[0095] The expansion agent also decomposes at elevated temperatures (eg, above 200° C.) and produces additional gas which expands the carbonaceous char in volume and produces a carbonaceous foam.

[0096] Therefore, it is preferred that the intumescent coating composition of the present invention comprises an acid generator, an intumescent agent and optionally a carbon donor compound.

[0097] Carbon Donor Compounds

[0098] If present, the carbon donor compound may comprise an organic polyol (i.e., an organic polyol) and / or expandable graphite. For example, the carbon donor compound may comprise pentaerythritol, dipentaerythritol, tripentaerythritol, a polysaccharide (e.g., starch, cellulose, glycogen, etc.), a disaccharide sugar (e.g., sucrose, lactose, maltose, etc.), a monosaccharide sugar (glucose, fructose, galactose, etc.), glycerol, or expandable graphite, or any combination thereof. Preferably, the carbon donor is pentaerythritol or dipentaerythritol.

[0099] Acid-generating compounds

[0100] The acid-generating compound may comprise a source of phosphoric or sulfonic acid that is capable of generating phosphoric or sulfonic acid upon exposure to heat, particularly at temperatures greater than 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.

[0101] In some examples, the acid-generating compound comprises a phosphate ester of a polyol, or an ammonium phosphate (eg, APP), or an amine phosphate (eg, melamine phosphate), or any combination thereof.

[0102] A particularly useful acid generating compound is ammonium polyphosphate, since APP generates phosphoric acid at a temperature generally lower than the decomposition temperature of the above-mentioned carbon donor compounds. Thus, APP generates phosphoric acid that is readily available to participate in the carbonization reaction.

[0103] APP compounds are polyphosphates with POP bonds and can be represented by the following formula:

[0104] [NH4PO3] n

[0105] wherein the average value of n is at least about 10. Particularly useful APP compounds in the intumescent coating compositions of the present invention include those having a value of n>1000.

[0106] The acid-generating compound may also comprise boric acid or a source of boric acid capable of generating boric acid upon exposure to heat, particularly at temperatures greater than 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, and any combination thereof.

[0107] Bulking Agent

[0108] The intumescent coating composition of the present invention may further comprise an expandable intumescent material (also referred to as a blowing agent). When exposed to fire or heat, the blowing agent generates a non-combustible gas, typically nitrogen. The generated gas expands the carbon derived from the carbon source to form a foamy protective layer. Suitable examples of commercially available blowing agents include, but are not limited to, nitrogen-containing compounds such as glycine, melamine, melamine salts, melamine derivatives, urea, urea derivatives, dicyandiamide, guanidine and isocyanurate derivatives, especially melamine.

[0109] Melamine derivatives include, for example, melamine formaldehyde, methylolated melamine, hexamethoxymethyl melamine, melamine monophosphate, di-melamine phosphate, melamine hydrogen phosphate (melamine diphosphate, melamine biphosphate), melamine polyphosphate, melamine pyrophosphate, melamine cyanurate, melamine borate, melam (N2-(4,6-diamino-1,3,5-triazine-2-yl)-1,3,5-triazine-2,4,6-triamine), melem (2,5,8-triamino-1,3,4,6,7,9,9b-heptaazaphenalene) and melon (poly[8-amino-1,3,4,6,7,9,9b-heptaazaphenalene-2,5-diyl)imino).

[0110] Urea derivatives include, for example, N-alkylureas such as methylurea; N,N′-dialkylureas such as dimethylurea; and N,N,N′-trialkylureas such as trimethylurea; guanylurea; guanylurea phosphate; formamide semicarbazide; guanylurea phosphate; 1,3-diaminourea; diurea, and the like.

[0111] Isocyanurate derivatives of interest include tris-(2-hydroxyethyl)isocyanurate (THEIC).

[0112] Boron-containing compounds useful as blowing agents in the present invention include, but are not limited to, boric acid and borates, such as ammonium pentaborate, zinc borate, sodium borate, lithium borate, aluminum borate, magnesium borate, and borosilicates.

[0113] The blowing agent may also include a monomeric or polymeric compound such as meso-lactide, polylactide, polysulfone, polycarbonate, polyester, 1,1-diactivated vinyl compound, or addition polymer of 1,1-diactivated vinyl compound, or any combination thereof.

[0114] Physical blowing agents such as expandable graphite and / or gas-doped expandable microspheres may also be used.

[0115] Thus, preferably the intumescent coating composition comprises:

[0116] i. Epoxy adhesive;

[0117] ii. Curing agent;

[0118] iii. expansion agent;

[0119] iv. acid-generating compounds;

[0120] v. a carbon donor compound; and

[0121] vi. At least 5 wt% water.

[0122] It is further preferred that the intumescent coating composition comprises:

[0123] i. Epoxy adhesive;

[0124] ii. Curing agent;

[0125] iii. Expanding agents containing melamine;

[0126] iv. an acid generating compound comprising ammonium polyphosphate;

[0127] v. a carbon donor compound; and

[0128] vi. At least 5 wt% water.

[0129] The intumescent coating composition may comprise 0.0 to 20 wt% carbon donor compound, such as 3.0 to 20 wt%, preferably 5.0 to 16 wt%, especially 7.0 to 14 wt% carbon donor compound, based on the total dry weight of the intumescent coating composition.

[0130] The intumescent coating composition may comprise 10 to 50 wt% of the acid generator, preferably 12 to 40 wt%, more particularly 15 to 30 wt%, based on the total dry weight of the intumescent coating composition.

[0131] The intumescent coating composition may comprise 3.0 to 20 wt% of an intumescent agent, preferably 5.0 to 16 wt%, especially 7.0 to 14 wt%, based on the total dry weight of the intumescent coating composition.

[0132] Epoxy Adhesive System

[0133] The epoxy-based adhesive system comprises a combination of one or more epoxy-based adhesives, one or more curing agents, and optionally a reactive diluent, a co-adhesive, a flame retardant, and an accelerator.

[0134] Epoxy Adhesives

[0135] The epoxy adhesive system preferably comprises one or more epoxy adhesives selected from aromatic or aliphatic epoxy adhesives, and the aromatic or aliphatic epoxy adhesives preferably contain more than one epoxy group per molecule. The epoxy groups can be located in internal or terminal positions on the epoxy adhesive or on the cyclic structure incorporated into the epoxy adhesive. Preferably, the epoxy adhesive contains at least two epoxy groups so that a cross-linked network can be formed.

[0136] It should be understood that the epoxy-based adhesives of the present invention also include adhesives having a traditional epoxy backbone but in which the epoxy end groups have been modified with acrylic or methacrylic functional groups which can be cured with the same curing agents as the epoxy groups.

[0137] Suitable aliphatic epoxy adhesives include epoxy and modified epoxy adhesives selected from alicyclic epoxies such as hydrogenated bisphenol A, hydrogenated bisphenol Anovolac and dicyclopentadiene adhesives, glycidyl ethers such as polyglycidyl ethers of polyols, epoxy functional acrylic resins, or any combination thereof.

[0138] Suitable aromatic epoxy adhesives include epoxy and modified epoxy adhesives selected from bisphenol type epoxy adhesives such as bisphenol A, bisphenol F and bisphenol S, resorcinol diglycidyl ether (RDGE), novolac type epoxy adhesives such as phenolic novolac type binder (phenolic novolac type binder) (bisphenol A novolac, bisphenol S novolac) and cresol novolac type binder, or any combination thereof.

[0139] In a preferred embodiment, the epoxy adhesive is an aromatic epoxy adhesive. Preferably, the aromatic epoxy adhesive is derived from a combination of a compound comprising at least one epoxide functional group and an aromatic co-reactant comprising at least two hydroxyl groups.

[0140] The preferred epoxy adhesive is a bisphenol epoxy adhesive. The preferred epoxy adhesive is a bisphenol A and bisphenol F epoxy adhesive or a bisphenol A / F epoxy adhesive. In a particularly preferred embodiment, the epoxy adhesive is a bisphenol A epoxy adhesive.

[0141] The epoxy adhesive may be a modified epoxy adhesive. Preferably, the epoxy adhesive is modified with fatty acid, polypropylene oxide and / or polyethylene oxide.

[0142] The solid content of the epoxy adhesive is preferably greater than 90 wt %, more preferably greater than 95 wt %, and most preferably greater than 98 wt %.

[0143] Epoxy adhesives can also be dispersed or emulsified in water. The adhesive can be appropriately chemically modified to improve water compatibility. The aqueous dispersion or emulsion containing the epoxy adhesive preferably also contains a surfactant, such as a polyether. In addition, other components such as emulsifiers, stabilizers, defoamers, dispersants and biocides may be present.

[0144] The aqueous dispersion or emulsion containing the epoxy-based adhesive preferably has a solid content of 20-60 wt.%, more preferably 40-60 wt.%, most preferably 50-60 wt.%.

[0145] Examples of suitable commercially available epoxy-based adhesives are:

[0146] -Bisphenol A epoxy adhesives: Epikote 828 from Hexion, Araldite GY 776 from Huntsman Advanced Materials.

[0147] - Bisphenol F epoxy adhesives: Epikote 862 from Hexion, YDF-170 from Kukdo, GY285 from Huntsman, DE 354 from Dow, BFE-170 from CCP, or KF8100 from Kolon.

[0148] - Mixtures of bisphenol A and bisphenol F: DER 352 from Dow Chemicals, or Epikote 235 from Hexion.

[0149] Dispersions of solid type 1 epoxy resins in water, for example Beckopox EP 2375 or Beckopox EP 2384 from Allnex, NPEW-261W55 from NaNya, BE3570W55 from CCP, EPI-REZ 3523 or EPI-REZ 6520 or EPI-REZ 7520 from Hexion.

[0150] The epoxy adhesive can be a liquid epoxy adhesive or a solid epoxy adhesive or a combination thereof. It should be understood that "liquid" and "solid" refer to the physical state of the epoxy adhesive at ambient temperature and pressure (25°C and 1 atm). In a preferred embodiment, the epoxy adhesive is a liquid epoxy adhesive. It should be noted that "liquid" and "solid" epoxy adhesives refer to the physical state of the adhesive before dispersing or emulsifying the adhesive in water if the epoxy adhesive is supplied in water.

[0151] The liquid epoxy-based adhesive may have an epoxy equivalent weight (EEW) value of 150 to 300, preferably 160 to 250 or more preferably 175 to 210.

[0152] When dispersed in water, the liquid epoxy adhesive may have an epoxide equivalent weight (EEW) value in delivered form of 150 to 800. Particularly preferred EEW is less than 500, such as 150 to 400, especially 250 to 350. The EEW of the emulsified liquid adhesive may be 100 to 300.

[0153] The solid epoxy-based adhesive may have an epoxy equivalent weight (EEW) value of 300 to 1000. However, it is most preferred that the EEW of the solid epoxy-based adhesive is in the range of 350-750, such as 400-700, especially 500-670.

[0154] When dispersed in water, the solid epoxy adhesive may have an epoxide equivalent weight (EEW) value in the delivered form of 150 to 2000. Particularly preferred EEWs are 500 to 1500, especially 800 to 1000. Most preferably, a solid bisphenol A epoxy adhesive is used.

[0155] The epoxy-based binder is preferably present in 5.0 to 60% by dry weight of the intumescent coating composition, such as 5.0 to 40% by dry weight of the intumescent coating composition. More preferably, the epoxy binder is present in 10 to 30% by dry weight of the intumescent coating composition, especially 12 to 28% by dry weight, most especially 16 to 25% by dry weight. If a blend of epoxy binders is used, these percentages refer to the total epoxy binder content, i.e. the dry weight % of each added.

[0156] All dry weight percentages given herein for the components in the intumescent coating composition also apply to the final content of these components in the intumescent coating. Thus, for example, the intumescent coating of the present invention further comprises 10 to 30 dry weight %, in particular 12 to 28 dry weight %, most in particular 16 to 25 dry weight % of epoxy binder.

[0157] In a preferred embodiment, the epoxy adhesive includes a bisphenol A adhesive, such as 4,4'-isopropylidenediphenol-epichlorohydrin resin, bisphenol F adhesive and / or novolac adhesive. Bisphenol A epoxy adhesives will be known to those skilled in the art and have the following general structure.

[0158]

[0159] In a preferred embodiment, the epoxy adhesive system comprises one or more bisphenol F epoxy adhesives.

[0160] The bisphenol F epoxy-based adhesive may have an EEW value of 100 to 350. However, it is particularly preferred that the EEW is 300 or less, such as 100 to 300, especially 150 to 250. Preferably, the bisphenol F epoxy-based adhesive is a liquid.

[0161] The Mw of the bisphenol F resin may be greater than 170 g / mol. Preferred bisphenol F (4',4'-methylene bisphenol) epoxy adhesives are derived from a combination of bisphenol F and epichlorohydrin. It is particularly preferred to use a difunctional epoxy bisphenol F adhesive.

[0162] Combinations of two or more bisphenol F adhesives may be used.

[0163] Curing agent

[0164] The epoxy-based adhesive system also comprises at least one curing agent. The curing agent may be any curing agent commonly known as a curing agent for epoxy-based adhesive systems. Ideally, the curing agent is an amine.

[0165] In order to obtain a cross-linked network, the curing agent must contain at least two "active" hydrogen atoms. "Active" hydrogen atoms are hydrogen atoms that transfer from nucleophiles to the oxygen atoms of the epoxide during the ring-opening reaction. Curing agents usually contain at least two curing-active functional groups (curing-reactive functional groups).

[0166] Examples of suitable curing agents are thiol curing agents, polythiol curing agents, amine curing agents, polyamine curing agents, amine-functional polyamides and / or amino-functional polymer curing agents. The curing agent may alternatively also comprise at least one amino-functional polysiloxane.

[0167] An example of a suitable polythiol curing agent is pentaerythrioltetramercapto propionate. An example of a suitable commercially available polythiol curing agent is GPM800.

[0168] In a preferred embodiment, the epoxy adhesive system comprises at least one amine functional curing agent. The curing agent generally contains at least two amine groups. The amine groups may be primary amine groups or secondary amine groups.

[0169] Suitable curing agents comprising amine or amino-functional polymers are selected from aliphatic amines and polyamines (e.g., cycloaliphatic amines and polyamines), amine-functional polyamides, polyetheramines, polyimidazoles, polyoxyalkyleneamines (e.g., polyoxyalkyleneamines), alkyleneamines (e.g., alkylenediamines), aralkylamines, aromatic amines, Mannich bases (e.g., those sold as "phenalkamines"), amino-functional silicones or silanes, and including epoxy adducts and derivatives thereof.

[0170] In a preferred embodiment, the amine functional curing agent comprises a cyclic structure, which includes alicyclic amines and modified products of alicyclic amines, preferably polyamines. The term cyclic includes alicyclic, aromatic and heterocyclic polyamines.

[0171] In one embodiment, adducts of amine curing agents may also be used. Such adducts may be prepared by reacting an amine with a suitable reactive compound such as an epoxy adhesive, an epoxy functional reactive diluent, an acrylate, a maleate, a fumarate, a methacrylate, or an electrophilic vinyl compound such as acrylonitrile.

[0172] Examples of suitable commercially available amine functional curing agents are:

[0173] Beckocure EH 2100, Beckopox 2385, Beckopox EP 2384, or Beckocure EH 2260 from Allnex; Aradur 3985BD or Aradur 943CH from Huntsman Advanced Materials; and EPIKURE 6870 or EPIKURE 8545 from Hexion.

[0174] In a particularly preferred embodiment, the curing agent is an aliphatic and / or cycloaliphatic polyamine.

[0175] It should be understood that the curing agent can be provided pure or in water. Surfactants and other chemicals suitable for improving water compatibility may also be present. Ideally, the curing agent does not contain solvents other than water. The amine functional curing agent is preferably emulsified in water. The solid content of the amine curing agent is preferably 40 to 80 wt %. The amine curing agent preferably contains 20-60 wt.% of water.

[0176] One or more curing agents may be used in combination. In a preferred option, two or more curing agents are used in combination.

[0177] The curing agent should cure the epoxy-based adhesive at a temperature in the range of 0 to 50° C. It is preferred that the epoxy-based adhesive system be cured at ambient temperature.

[0178] The equivalent weight of a curing agent is often quoted as "active hydrogen equivalent weight". The amount of "active hydrogen equivalents" associated with one or more curing agents is the sum of the contributions from each of the one or more curing agents. The contribution to the active hydrogen equivalents from each of the one or more curing agents is defined as the grams of curing agent divided by the active hydrogen equivalent weight of the curing agent, where the active hydrogen equivalent weight of the curing agent is determined as the grams of curing agent equivalent to 1 mole of active hydrogen. For adducts with epoxy resins, the contributions of the pre-adducted reactants are used to determine the amount of "active hydrogen equivalents" in the complete epoxy adhesive system.

[0179] It is also common to quote the number of "epoxy equivalents" in epoxy adhesives. "Epoxy equivalents" is the sum of the contributions from each of the one or more epoxy adhesives and any other epoxy-containing components such as silanes or reactive diluents. The contribution to the epoxy equivalent from each of the one or more epoxy adhesives is defined as the grams of epoxy adhesive divided by the epoxy equivalent weight of the epoxy adhesive, where the epoxy equivalent weight of the epoxy adhesive is determined as the grams of epoxy resin equivalent to 1 mol of epoxide groups. For adducts with epoxy adhesives, the contribution of the pre-adduct reactants is used to determine the number of "epoxy equivalents" in the epoxy adhesive system.

[0180] Preferably, the ratio between the hydrogen equivalent of the total amount of the curing agent and the total amount of the epoxy equivalent in the epoxy-based adhesive system of the present invention is in the range of 50:100 to 120:100.

[0181] Particularly preferred epoxy-based adhesive systems have a ratio between the hydrogen equivalent of the curing agent and the epoxy equivalent of the epoxy resin in the range of 60:100 to 120:100, such as 80:100 to 120:100, for example 90:100 to 110:100.

[0182] It should be understood that the curing agent is shipped separately from the epoxy adhesive and is mixed with the epoxy adhesive only shortly before application. Of course, the mixing ratio of the composition comprising the epoxy adhesive and the curing agent is determined by the relative amounts of epoxy and active hydrogen present. Ideally, the solid volume mixing ratio is 1:1 to 10:1. The curing agent composition and the epoxy adhesive composition are mixed shortly before application to the substrate.

[0183] In one embodiment, the curing agent may be present in the intumescent coating composition in the range of 1 to 25 dry weight %, such as 5 to 20 dry weight %.

[0184] Although a curing accelerator may be used, in a preferred embodiment, the curing agent is used without a separate accelerator to accelerate the crosslinking process. However, some known curing agents are combined with accelerators such as tertiary amine catalysts, and this is also within the scope of the present invention.

[0185] Active diluent

[0186] The epoxy-based adhesive system may also contain a reactive diluent. The reactive diluent preferably contains epoxy and / or (meth) acrylic functional groups. The reactive diluent forms part of the adhesive system and reacts with other components of the adhesive system during the curing process.

[0187] In a preferred embodiment, the reactive diluent is an epoxy functional reactive diluent. The epoxy functional reactive diluent may be monofunctional or difunctional.

[0188] Examples of such reactive diluents include phenyl glycidyl ether, alkyl glycidyl ether (the number of carbon atoms in the alkyl group: 1 to 16), glycidyl ester of neodecanoic acid (R 1 R 2 R 3 C-COO-Gly, where R 1 R 2 R 3 is an alkyl group such as a C8 to C10 alkyl group and Gly is a glycidyl group), olefin epoxides (CH3-(CH2)n-Gly, wherein n=11 to 13, Gly: glycidyl group), 1,4-butanediol diglycidyl ether (Gly-O-(CH2)4-O-Gly), 1,6-hexanediol diglycidyl ether (Gly-O-(CH2)6-O-Gly), neopentyl glycol diglycidyl ether (Gly-O-CH2- C(CH3)2-CH2-O-Gly), trimethylolpropane triglycidyl ether (CH3-CH2-C(CH2-O-Gly)3) and C1-20-alkylphenyl glycidyl ether (preferably C1-5 alkylphenyl glycidyl ether), such as methylphenyl glycidyl ether, ethylphenyl glycidyl ether, propylphenyl glycidyl ether and p-tert-butylphenyl glycidyl ether (p-TBPGE), the reaction product of epichlorohydrin and oil obtained from cashew nut shell.

[0189] In a preferred embodiment, the epoxy-functional reactive diluent is the reaction product of epichlorohydrin and oil obtained from cashew nut shells, such as, for example, Cardolite NC-513 from Cardolite.

[0190] In another particularly preferred embodiment, the epoxy-functional reactive diluent is an aliphatic epoxy-functional reactive diluent. The aliphatic epoxy-functional reactive diluent is preferably formed by the reaction of a compound containing at least one aliphatic epoxide functional group (functionality) with an aliphatic alcohol or polyol, such as 1,6-hexanediol diglycidyl ether or 1,4-butanediol diglycidyl ether. Also preferred are aliphatic glycidyl ethers with a chain length of 8 to 14. The aliphatic epoxy-functional reactive diluent can contribute to the flexibility of the coating film.

[0191] The epoxy equivalent weight (EEW) of the epoxy functional reactive diluent is preferably from 50 to 500, more preferably from 100 to 400, and most preferably from 100 to 300.

[0192] Epoxy functional reactive diluents are different from epoxy adhesives. Preferably the reactive diluent has a low molecular weight, such as a molecular weight of less than 500 g / mol. Preferably the viscosity of the epoxy functional reactive diluent is <100 cp, preferably <50 cp, preferably <35 cp. Therefore, it is liquid at 23°C and atmospheric pressure.

[0193] In another preferred embodiment, the reactive diluent comprises a (meth)acrylic acid functional group.

[0194] The (meth)acrylic acid functional reactive diluent is preferably an aliphatic (meth)acrylate ester comprising at least two (meth)acrylate functional groups connected by an organic linker. Such a polyester may be a diester, triester or tetraester.

[0195] The molecular weight of (meth) acrylate functional reactive diluent is preferably less than 1000, such as less than 750, especially less than 500g / mol.Ideally, (meth) acrylic acid functional reactive diluent will be a (meth) acrylate of a polyol such as a diol or a triol or a sugar-based polyol such as a sugar alcohol.It is not necessary that all OH groups in the polyol carry a (meth) acrylate group, however, in the (meth) acrylate, preferably at least two ester functional groups should be present.Suitable polyols for functionalization include alkylene glycols (for example hexylene glycol, pentylene glycol), sugars (for example monosaccharides or disaccharides) or polyols (especially sugar alcohols), such as erythritol, sorbitol, maltitol and mannitol.

[0196] The (meth)acrylic acid functional reactive diluents of particular interest have the formula

[0197]

[0198] Wherein R is H or Me;

[0199] n is 2-5; and

[0200] L represents a residue of a polyol, such as a residue of hexanediol, or a residue of a sugar or sugar alcohol. Thus, at least two OH groups of the polyol carry an acrylate of the above formula.

[0201] L preferably contains only C, H and O atoms. The molecular weight of L is preferably low, such as 1000 g / mol or less.

[0202] The amount of "acrylate equivalents" in a (meth)acrylic functional reactive diluent is often cited. "Acrylic equivalents" is the sum of the contributions from each of the one or more (meth)acrylic functional reactive diluents. The contribution to the acrylate equivalents from each of the one or more (meth)acrylic functional reactive diluents is defined as the grams of (meth)acrylic functional reactive diluent divided by the acrylate equivalent weight of the (meth)acrylic functional reactive diluent, wherein the acrylate equivalent weight of the (meth)acrylic functional reactive diluent is determined as the grams of (meth)acrylic functional reactive diluent equivalent to 1 mole of acrylate groups. For adducts with curing agents, the contributions of the pre-adduct reactants are used to determine the amount of "acrylate equivalents" in the complete (meth)acrylic functional reactive diluent system. When formulated, the "acrylate equivalents" are often included in the total "epoxy equivalents".

[0203] A particularly preferred (meth)acrylic reactive diluent is trimethylolpropane triacrylate.

[0204] The viscosity of the (meth)acrylic acid functional reactive diluent is preferably less than 300 mPas, more preferably less than 200 mPas, most preferably less than 150 mPas.

[0205] Preferred (meth)acrylic functional reactive diluents have an acrylate equivalent weight (AEW) value of 50-200, more preferably 70-150, and most preferably 80-125.

[0206] Mixtures of (meth)acrylic functional reactive diluents may also be used.

[0207] The above-mentioned reactive diluents may be used alone or in combination of two or more diluents.

[0208] The reactive diluent is preferably present in an amount of 0.25 to 15 dry weight percent, preferably 0.5 to 10 dry weight percent, more preferably 0.5 to 7.0 dry weight percent, especially 1.0 to 6.0 dry weight percent, more especially 1.0 to 5.0 dry weight percent of the intumescent coating composition. If a blend of reactive diluents is used, these percentages refer to the total content of reactive diluents, i.e. the wt % of each added.

[0209] It will be appreciated that, because the reactive diluent may react with the curing agent, it should be kept separate from the curing agent in the kit used to form the intumescent coating composition.

[0210] Silane

[0211] The coating composition of the present invention may include at least one silane. The silane is part of the binder system and reacts with the other components of the binder system during curing. Preferably, the silane is a functional silane containing functional groups such as amine, epoxy, acryl, methacryl, thiol and isocyanate groups that can react with the binder system. The silanes used in the present invention generally have a low Mw, such as an Mw of less than 400 g / mol. Suitable silanes have the general formula (I) or (II)

[0212] (I)YR (4-z) SiX z

[0213] Where z is an integer from 1 to 3,

[0214] (II) YR (3-y) R 1 SiX y

[0215] Where y is an integer from 1 to 2,

[0216] Each R is a hydrocarbon radical having 1 to 12 C atoms, optionally containing an ether or amino linker, 1 is a hydrocarbon group having 1 to 12 C atoms;

[0217] Each X independently represents a halogen group or an alkoxy group.

[0218] Y is a functional group bonded to R, and R can react with an epoxy adhesive and / or a curing agent.

[0219] Preferably, Y is an isocyanate, epoxy, amino, hydroxyl, carboxyl, thiol, acrylate or methacrylate group, more preferably an epoxy, amino, acrylate or methacrylate group, most preferably an epoxy or amino group. Particularly preferably, Y is an epoxy group. The Y group may be combined with any part of the chain R. It should be understood that, in the case where Y represents an epoxy group, then R will have at least two carbon atoms to allow the formation of an epoxide ring system.

[0220] In a particularly preferred embodiment, Y is an amino group or an epoxy group. The amino group is preferably NH2. Preferably, Y is an epoxy group.

[0221] If the Y group is an amino group reactive with epoxy-based adhesives, it is preferred that the silane is provided separately from the epoxy-based adhesive along with the curing agent. Generally, in the kit of the present invention, the silane should not react with any component of the kit composition in which the silane is present.

[0222] Each X independently represents a halogen group or an alkoxy group. It is particularly preferred that X is an alkoxy group, such as a C1-6 alkoxy group, especially a methoxy group or an ethoxy group. It is also particularly preferred that two or three alkoxy groups are present. Therefore, z is ideally 2 or 3, especially 3.

[0223] The subscript y is preferably 2.

[0224] R 1 Preferred is a C1-4 alkyl group, such as methyl.

[0225] R is a hydrocarbon radical having up to 12 carbon atoms. A hydrocarbon radical refers to a radical containing only C and H atoms. It may contain an alkylene chain or a combination of an alkylene chain and a ring such as a phenyl or cyclohexyl ring. The term "optionally containing an ether or amino linker" means that the carbon chain may be interrupted by -O- or -NH- groups in the chain, for example to form silanes, such as [3-(2,3-epoxypropoxy)propyl]trimethoxysilane:

[0226] H2COCHCH2OCH2CH2CH2Si(OCH3)3.

[0227] R is preferably an unsubstituted (obviously except for Y), unbranched alkyl chain having 2 to 8 C atoms.

[0228] Thus, a preferred silane has the structure (III)

[0229] (III)Y'-R'( 4-z' )SiX' z

[0230] Wherein z' is an integer from 2 to 3,

[0231] R' is an unsubstituted, unbranched alkyl chain with 2 to 8 C atoms, optionally containing an ether or amino linker,

[0232] Y' is an amino or epoxy functional group bonded to the R' group, and

[0233] X' represents an alkoxy group.

[0234] Examples of such silanes are represented by the products manufactured by Degussa in Rheinfelden and sold under the trade name Dynasylan(R) D, Silquest(R) silanes manufactured by Momentive, and GENOSIL(R) silanes manufactured by Wacker.

[0235] Specific examples include methacryloxypropyltrimethoxysilane (Dynasylan MEMO, Silquest A-174NT), 3-mercaptopropyltri(meth)ethoxysilane (Dynasylan MTMO or 3201; Silquest A-189), 3-glycidoxypropyltrimethoxysilane (Dynasylan GLYMO, Silquest A-187), tris(3-trimethoxysilylpropyl)isocyanurate (Silquest Y-11597), γ-mercaptopropyltrimethoxysilane (Silquest A-189), β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (Silquest A-186), γ-isocyanatopropyltrimethoxysilane (γ-isocyanatopropyltrimethoxysilane, gamma-isocyanatopropyltrimethoxysilane) (Silquest A-Link 35, Genosil GF40), (methacryloyloxymethyl)trimethoxysilane (Genosil XL33), isocyanatomethyl)trimethoxysilane (isocyanatomethyl)trimethoxysilane) (Genosil XL 43), aminopropyltrimethoxysilane (Dynasylan AMMO; SilquestA-1 110), aminopropyltriethoxysilane (Dynasylan AMEO) or N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (Dynasylan DAMO, Silquest Al 120) or N-(2-aminoethyl)-3-aminopropyltriethoxysilane, triaminofunctional trimethoxysilane (Silquest A-1130), bis(γ-trimethoxysilylpropyl)amine (Silquest Al 170), N-ethyl-γ-aminoisobutyltrimethoxysilane (Silquest A-Link 15), N-phenyl-γ-aminopropyltrimethoxysilane (Silquest Y-9669), 4-amino-3,3-dimethylbutyltrimethoxysilane (Silquest Yl 1637), (N-cyclohexylaminomethyl)triethoxysilane (Genosil XL 926), (N-phenylaminomethyl)trimethoxysilane (Genosil XL 973), Deolink Epoxy TE and Deolink Amino TE (DOG Deutsche Oelfabrik) and mixtures thereof.

[0236] Other specific silanes of interest include 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-(aminoethyl)-aminopropyltrimethoxysilane H2NCH2CH2NHCH2CH2CH2Si(OCH3)3, 3-aminopropylmethyldiethoxysilane, 3-(2-aminoethylamino)propylmethyldimethoxysilane, (H2NCH2CH2NHCH2CH2CH2SiCH3(OCH3)2), [3-(2,3-epoxypropoxy)propyl]triethoxysilane (H2COCHCH2OCH2CH2CH2Si(OCH2CH3)3, [3-(2,3-epoxypropoxy)propyl]trimethoxysilane (H2COCHCH2OCH2CH2CH2Si(OCH3)3). Silanes delivered in water from Dynasylan: Aqueous 3-aminopropylsilane Hydrolysate Hydrosil 1151 or Hydrosil 1153, reactive organofunctional siloxane oligomers in water Hydrosil 2775 or Hydrosil 2776.

[0237] The silane 3-glycidyloxypropyltrimethoxysilane is particularly preferably used. Mixtures of silanes can also be used.

[0238] The amount of silane present in the intumescent coating composition may be present in an amount of 0.1 to 15 wt%, preferably 0.25 to 15 wt.%, such as 0.5 to 10 wt.%, more preferably 0.5 to 7.0 wt.%, especially 1.0 to 6.0 wt.%, more especially 1.0 to 5.0 wt.% of the dry weight of the coating composition. In some embodiments, the silane is present in an amount of 1.5 to 4.5 wt.% of the dry weight of the intumescent coating composition. If a blend of silanes is used, these percentages refer to the total silane content, i.e. the wt.% of each added.

[0239] It should be understood that if the silane contains functional groups that are reactive with the epoxy binder, it should be kept separate from the epoxy binder in the kit used to form the intumescent coating composition.

[0240] Accelerator

[0241] The epoxy adhesive system may include a curing accelerator. The curing accelerator may be any known curing accelerator for epoxy coating systems, such as tertiary amines, (meth)acrylates, imidazoles, organic acids, phenols, and organic phosphines.

[0242] Examples of suitable tertiary amines are triethanolamine, dialkylaminoethanol, triethylenediamine, 1,4-diazabicyclo[2.2.2]octane, 1,8-diaza-bicyclo[5.4.0]undec-7-ene and 2,4,6-tris(dimethylaminomethyl)phenol. A particularly preferred accelerator is 2,4,6-tris(dimethylaminomethyl)phenol, such as Ancamine K54 from Evonik.

[0243] Examples of suitable imidazoles are 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole and 2-heptadecylimidazole.

[0244] Examples of suitable organic acids are benzoic acid derivatives, such as salicylic acid.

[0245] Examples of suitable organic phosphines are tributylphosphine, methyldiphenylphosphine, triphenylphosphine, diphenylphosphine and phenylphosphine.

[0246] Examples of suitable phenols are alkylphenols, such as nonylphenol.

[0247] Examples of suitable (meth)acrylates are the same as described above for the (meth)acrylate functional reactive diluents.

[0248] Flame retardants

[0249] The binder system may also include at least one flame retardant, such as a phosphorus-containing flame retardant. Suitable flame retardants include phosphoric acid, phosphites, phosphonates, and phosphates. Halogen-based flame retardants may also be used, such as tris(2-chloroisopropyl)phosphate.

[0250] Preference is given to using triaryl phosphates, especially triphenyl phosphate. Where a flame retardant is used, this must be distinct and therefore separate from any other components of the intumescent coating.

[0251] Preferably, the flame retardant comprises 2.0 to 10 dry weight %, preferably 2.5 to 10 dry weight %, for example 2.5 to 8.0 dry weight %, especially 3.0 to 8.0 dry weight % of the intumescent coating composition.

[0252] Additives that do not form part of the adhesive system

[0253] The intumescent coating composition may also contain various other components. In particular, the intumescent coating composition may include additives selected from pigments, fillers, nucleating agents, coalescing agents, dispersants, defoamers and rheology modifiers.

[0254] Fillers may optionally be added to the coating composition to, among other things, aid in char formation and strengthen the char and prevent char degradation (e.g., act as a char reinforcing agent). Such fillers include solids such as zinc borate, zinc stannate, zinc hydroxystannate, glass flakes, glass spheres, polymer spheres, fibers (ceramic, mineral, glass / silica type), aluminum hydroxide, antimony oxide, boron phosphate, and fumed silica. Fillers preferably constitute from 1% to 25% of the dry weight of the intumescent coating composition.

[0255] Inorganic "nucleating" agents may also be included in the intumescent coating compositions of the present invention as they provide sites for the intumescent char to form and improve the thermal resistance and stability of the intumescent char during a fire.

[0256] Thus, the intumescent coating composition of the present invention may contain a nucleating agent, examples of which include titanium dioxide, zinc oxide, aluminum oxide, silica, silicates, heavy metal oxides such as cerium oxide, lanthanum oxide and zirconium oxide, calcium carbonate, carbon black, talc, wollastonite, micaceous iron oxide, china clay, mica and bentonite.

[0257] Examples of color pigments include titanium white, red iron oxide, yellow iron oxide, black iron oxide, carbon black, and organic color pigments.

[0258] As rheology modifiers, thixotropic agents suitable for aqueous formulations may be used, such as cellulosic thickeners, xanthan gum, guar gum, organically modified clays such as bentonite, hectorite and attapulgite clays, organic wax thixotropic agents based on castor oil and castor oil derivatives, polyamide waxes and pyrogenic silicas.

[0259] A low viscosity water soluble hydrocarbon resin may optionally be included as a hydrophobic modifier, such as to improve flexibility, corrosion protection and drying time. Examples of suitable commercially available water soluble hydrocarbon resins include NOVARES W, NOVARES WA2, NOVARES WA7 and NOVARES CA 80.

[0260] Coalescing agent can be optionally included.In waterborne coating compositions, the wet product applied is inhomogeneous, which is opposite to solventborne compositions, which are uniform when applied.When the applied composition is inhomogeneous, the risk of having epoxy-rich and epoxy-deficient (rich in curing agent) regions in the cured film is higher.This will result in incomplete curing, uneven appearance, rough surface and weakened film properties.In order to achieve a fully cured system, epoxy particles must coalesce (combine, coalesce) with curing agent particles.Coalescing agent helps this process in the aqueous phase.The example of suitable coalescing agent is 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 (diacetone alcohol) (DAA) and dipropylene glycol methyl ether (DPM).

[0261] In order to improve or facilitate the dispersion of the intumescent ingredient in the waterborne intumescent coating composition, it may be desirable to incorporate a wetting / dispersing additive that is compatible with the waterborne intumescent coating.

[0262] Suitable polar dispersants are highly polar oligomers or polymers, such as those containing a plurality of hydroxyl, carboxyl, amino or amide groups or mixtures of these groups. Thus, the term polar is used herein to define dispersants containing a plurality of, for example at least 10, polar functional groups selected from hydroxyl, carboxyl, amino or amide groups. Suitable materials include polyalkylene glycols, polyacrylamides, polyether carboxylates (polyether carboxylates) and polycarboxylates (polycarboxylates).

[0263] Typically, from 0.1 to 2.0 dry weight percent of the dispersant may be present in the intumescent coating composition.

[0264] Therefore, viewed from another aspect, the present invention provides an intumescent coating system comprising:

[0265] B) Intumescent coating;

[0266] C) top coating;

[0267] The intumescent coating includes:

[0268] i. Epoxy adhesive;

[0269] ii. Curing agent;

[0270] iii. Polar dispersants;

[0271] iv. a bulking agent; and

[0272] v. Acid-generating compounds;

[0273] The top coating layer includes an acrylic adhesive, a polyurethane adhesive or a silicone adhesive.

[0274] Anticorrosive components may also be included in the coating composition. These components may be metal oxides, metal carbonates, talc, feldspar, etc. as anticorrosive materials. Specific anticorrosive functional pigments include zinc phosphate, zinc oxide, zinc powder, aluminum flakes, and lead oxide. Auxiliary corrosion inhibitors, such as 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.

[0275] The total amount of the above-mentioned various additive components depends on the use and cannot be determined arbitrarily, but they are usually contained in the intumescent coating composition in a total content of 5.0 to 65 dry weight %, such as 5.0 to 50 dry weight %, preferably 5.0 to 30 dry weight %.

[0276] Preparation of intumescent coating compositions

[0277] The intumescent coating composition may be prepared by any suitable technique commonly used in the field of coating production. Thus, the various ingredients may be mixed together using a high speed disperser, a ball mill, a bead mill, a three-roll mill, an inline mixer, or the like.

[0278] Conveniently, the intumescent coating composition is provided in the form of a kit of parts. Part (A) comprises the epoxy resin and part (B) comprises the curing agent. Inactive components such as fillers and pigments and the intumescent component may be provided in part (A) or (B). If present, the reactive diluent is conveniently added to part (A) as it reacts with the curing agent. The skilled person will be able to design a suitable kit to supply the components for transport.

[0279] It will be appreciated that the relative amounts of each component within any part of the kit will be determined by the final wt% values ​​and relative mixing ratios in the intumescent coating composition.

[0280] The intumescent coating composition to be used herein is conveniently prepared by mixing the components. For example, the first composition (A) and the curing agent component (B) (second composition) can be mixed by adding the curing agent to the epoxy first composition and stirring thoroughly until the mixture is homogeneous. The mixture is immediately ready for application, for example by spray application or manually, but an induction time can also be given before application. Alternative spraying equipment designed specifically for two-component application, high viscosity coatings do not require premixing of the two components. Mechanical mixing of the two components is then performed just before the coating reaches the application gun, allowing the composition to be conveniently applied. In contrast, the curing agent component (B) (second composition) can be introduced by a multi-component spray gun configuration and mixed with the epoxy first composition (A) immediately before contact with the substrate.

[0281] Application of intumescent coating compositions

[0282] The intumescent coating composition may be applied to a substrate, particularly a steel structure, by spraying, for example using well-known airless spray techniques, or manually using, for example, a brush.

[0283] When an intumescent coating composition is applied, a mesh or scrim embedded in the intumescent coating may be incorporated. The mesh or scrim is typically composed of one or a combination of glass, carbon, basalt or some other high temperature resistant fiber based material. These may also contain or be combined with fine metal wires such as carbon or stainless steel. Such meshes are typically used in systems to provide a reinforcing element or to control the intumescent foam formed during the expansion reaction. Preferably, the intumescent coating composition of the present invention does not contain a mesh or scrim.

[0284] Film thickness

[0285] The intumescent coating composition is applied at a high dry film thickness to ensure good fire protection. Depending on the nature of the coated substrate and its predicted fire exposure scenario, the applied film thickness may vary. The dry film thickness of the intumescent coating is preferably from 0.1 to 8.0 mm, for example from 0.1 to 4.0 mm, especially from 0.2 to 2.0 mm. The intumescent coating composition may be applied multiple times to achieve a suitable dry film thickness.

[0286] Curing

[0287] Once the substrate is coated with the intumescent coating composition, the intumescent coating composition must be cured. The intumescent coating composition may cure spontaneously. Although heat may be used to accelerate curing, the compositions of the present invention cure at ambient temperature without further intervention.

[0288] In a further aspect, the present invention comprises a method wherein a coating of an intumescent coating composition is applied to a basecoat of a primer composition.

[0289] In a particularly preferred embodiment, the intumescent coating is prepared from an intumescent coating composition comprising:

[0290] (i) 10 to 30% by dry weight of at least one epoxy binder;

[0291] (ii) at least one curing agent;

[0292] (iii) 12 to 40% by dry weight of an acid-generating compound;

[0293] (iv) 1.0 to 15% by dry weight of a bulking agent;

[0294] (v) 1.0 to 15% by dry weight of a carbon donor compound;

[0295] (vi) 10 to 30 wt% of water.

[0296] Primer layer

[0297] Preferably the substrate has a primer layer therein, onto which the intumescent coating composition is applied. The primer layer is conventional and is typically formed from an epoxy resin, but other options may be used. The primer layer preferably comprises at least 20 wt % epoxy resin, preferably at least 25 wt % epoxy resin.

[0298] Examples of suitable primer layers are coatings based on epoxy resins, modified epoxy resins (such as modified with polyvinyl butyral), polyurethane, acrylic, vinyl and chlorinated rubber. Preferably, the primer layer is an epoxy-based primer or a zinc-rich epoxy-based primer.

[0299] In another embodiment, the primer layer is a polysiloxane sol primer, such as described in US2014 / 0106176. Polysilane sol can be a component formed by the condensation reaction of at least one silane to form a highly branched polysilane sol containing multiple free silanol functional groups. Polysilane sol can be derived from at least one alkoxysilane precursor, which has undergone hydrolysis to form corresponding silanols. It should be understood that in many alkoxysilanes, there are multiple alkoxy groups (usually up to three such groups), and therefore there may be multiple hydrolysis products according to the hydrolysis procedure. Completely hydrolyzed and partially hydrolyzed products can be formed. The hydrolysis reaction leads to the formation of alcohols.

[0300] The hydrolyzed silanes / partially hydrolyzed silanes can then be condensed together to form complex oligomers / polymers as is well known. Due to the presence of various different monomers when the hydrolysis reaction is carried out, the complex polysilane sol forms cannot be easily characterized by a general formula.

[0301] The dry film thickness of the primer is ideally in the range of 15 to 500 microns.

[0302] Top coating

[0303] The topcoat is applied over the intumescent coating, the intumescent coating resulting from the curing of the intumescent coating composition.The topcoat is obtained by applying the topcoat composition to the intumescent coating, the intumescent coating optionally being cured or partially cured prior to applying the topcoat composition.

[0304] The topcoat composition is preferably aqueous.

[0305] For example, the topcoat is preferably non-intumescent, e.g., it should not contain acid-generating compounds and / or intumescent agents. The topcoat should be decorative rather than intumescent.

[0306] The presence of intumescent components such as acid generating components or intumescent agents in the topcoat may limit the options available to the skilled artisan in terms of the properties of the topcoat. By concentrating the components having fire retardant properties in one layer, the fire retardant properties are also not dependent on the topcoat and the skilled artisan has greater flexibility in selecting the topcoat material.

[0307] Preferably, the topcoat composition does not contain any low boiling point organic solvents and thus has a low content of volatile organic compounds (VOC). The VOC content of the topcoat composition is preferably less than 150 g / L, more preferably less than 100 g / L. In this regard, the volatile organic compound includes benzyl alcohol.

[0308] However, the topcoat composition must be aqueous.Preferably, the topcoat composition has a volume solids content of at least 35%, such as at least 50%, for example 50 to 60% volume solids.

[0309] The topcoat composition may comprise at least 10 wt% water, such as at least 20 wt% water, such as at least 30 wt% water, for example 30 to 50 wt% water. In a preferred embodiment, the topcoat composition comprises greater than 30 wt% water.

[0310] The top coating composition comprises an acrylic adhesive, a polyurethane adhesive or a silicone adhesive. Acrylic adhesives and polyurethane adhesives are preferably used. In a particularly preferred option, the top coating composition comprises an acrylic adhesive.

[0311] Polysiloxane adhesive

[0312] The polysiloxane-based binder present in the top coating of the present invention can generally be any curable polysiloxane. As used herein, when referring to polysiloxane, the term "curable" means that the polysiloxane contains functional groups that enable crosslinking reactions to occur directly between polysiloxane molecules or through a crosslinking agent. Preferably, the polysiloxane-based binder is moisture curable.

[0313] The polysiloxane adhesive is preferably an organopolysiloxane with terminal and / or side chain curing active functional groups. Preferably, at least two curing active functional groups (curing reactive functional groups) per molecule. Preferably, the coating composition comprises a polysiloxane with greater than 2, preferably greater than 3 functional groups (functionality). The example of the curing active functional group is a silanol, an alkoxyl group, an acetoxyl group, an alkeneoxy group, a ketoxime, an alcohol, an amine, an epoxy group and / or an isocyanate. Ideally, there is no vinyl group.

[0314] Therefore, in a particularly preferred embodiment, the polysiloxane-based adhesive is not cured via the vinyl functionality.Polysiloxanes are ideally condensation cured.

[0315] Preferred curing active functional groups are selected from silanol, alkoxy or acetoxy. Particularly preferred are alkoxy functional polysiloxanes, especially methoxy functional polysiloxanes. As used herein, the term "alkoxy functional polysiloxane" includes but is not limited to alkoxy-silyl functional polysiloxanes. In another preferred embodiment, the curing active functional group is silanol. Optionally, the polysiloxane adhesive comprises more than one type of curing active functional group. Preferably, at least one polysiloxane adhesive comprises a single type of curing active functional group.

[0316] The curing reaction is typically a condensation cure reaction.Polysilicone-based adhesives optionally contain more than one type of cure-reactive group and may cure, for example, by both condensation cure and amine / epoxy cure.

[0317] The polysiloxane-based binder present in the coating composition of the present invention generally comprises at least 30 wt% polysiloxane moieties, preferably more than 50 wt% polysiloxane moieties and still more preferably more than 70 wt% polysiloxane moieties, such as 99.99 wt% polysiloxane moieties or more.

[0318] The polysiloxane moiety is defined as a repeating unit comprising the motif -Si-O-, based on the total weight of at least one polysiloxane. The wt.% of the polysiloxane moiety can be determined based on the stoichiometric wt. ratio of the starting materials in the polysiloxane synthesis. Alternatively, analytical techniques such as IR or NMR can be used to determine the polysiloxane content. Information on the wt.% polysiloxane moiety in commercially available polysiloxanes can be readily obtained from suppliers.

[0319] It should be understood that the polysiloxane-based adhesive may comprise a polysiloxane consisting of a single repeating sequence of siloxane units or interrupted by non-siloxane moieties, such as organic moieties.

[0320] The organic portion may include, for example, an alkylene group, an arylene group, a poly(alkylene oxide), an amide, a thioether, or a combination thereof, preferably, the organic portion may include, for example, an alkylene group, an arylene group, a poly(alkylene oxide), an amide, or a combination thereof.

[0321] The coating composition may comprise only one type of polysiloxane-based binder or may comprise a mixture of different polysiloxane-based binders.

[0322] In a preferred embodiment, the coating composition comprises a branched polysiloxane adhesive, more preferably a branched alkoxy-functional polysiloxane adhesive or a branched silanol-functional polysiloxane adhesive. Most preferably, a branched methoxy-functional polysiloxane adhesive. Branched means that the polysiloxane chain is branched. In a preferred embodiment, the branched polysiloxane adhesive comprises a cage-like polysiloxane structure.

[0323] In a most preferred embodiment, the coating composition comprises a branched polysiloxane-based binder containing methyl and phenyl groups.

[0324] A preferred polysiloxane binder present in the coating composition of the present invention is represented by the following formula (D1):

[0325]

[0326] in

[0327] Each R 1 Independently selected from hydroxyl, C 1-6 -alkoxy, C 1-6 -Hydroxyl, containing C 1-6 -Epoxy group (C 1-6 Epoxy-containing groups, C 1-6 -epoxy containing group), C 1-6 Amine, C 1-10 Alkyl, C 6-10 Aryl, C 7-10 Alkyl aryl or O-Si(R 5 ) 3-z (R 6 ) z

[0328] Each R 2 Independently selected from C 1-10 Alkyl, C 6-10 Aryl, C 7-10 Alkyl aryl or C substituted by poly(alkylene oxide) (poly(alkylene oxide), poly(alkylene oxide), poly(alkylene oxide)) 1-6 Alkyl and / or for R 1 The group described;

[0329] Each R 3 and R 4 Independently selected from C 1-10 Alkyl, C 6-10 Aryl, C 7-10 Alkyl aryl or poly (alkylene oxide) substituted C 1-6 alkyl;

[0330] Each R 5 is independently a hydrolyzable group such as C 1-6 an alkoxy group, an acetoxy group, an enoxy group or a ketoxy group;

[0331] Each R 6 Independently selected from unsubstituted or substituted C 1-6 alkyl;

[0332] z is 0 or an integer from 1 to 2;

[0333] x is an integer at least 2;

[0334] y is an integer of 0 or at least 1.

[0335] Preferably, R 1 Selected from hydroxyl and O-Si(R 5 ) 3-z (R 6 ) z , where R 5 is C1-C6 alkoxy, R 6 C 1-6 alkyl and z is 0 or an integer from 1 to 2. More preferably, R 1 Selected from hydroxyl and O-Si(R 5 ) 3-z (R 6 ) z , where R 5 is C1-C3 alkoxy, R 6 C 1-3 alkyl and z is 0 or an integer from 1 to 2. Most preferably, R1 is O—Si(R 5 ) 3-z (R 6 ) z , where R 5 is a C1-C3 alkoxy group, R 6 It is C 1-3 and z is 0 or an integer from 1 to 2.

[0336] Preferably, R 2 C 1-10 Alkyl, C 6-10 Aryl, C 7-10 Alkyl aryl or O-Si(R 5 ) 3-z (R 6 ) z .

[0337] Preferably, R 3 C 1-10 Alkyl or C 6-10More preferably, R 3 C 1-4 Alkyl or C6 aryl, more preferably C 1-2 An alkyl group or a C6 aryl group, and still more preferably a methyl group or a phenyl group.

[0338] Preferably, R 4 C 1-10 Alkyl or C 6-10 More preferably, R 3 C 1-4 Alkyl or C6 aryl, more preferably C 1-2 An alkyl group or a C6 aryl group, and still more preferably a methyl group or a phenyl group.

[0339] The weight average molecular weight (Mw) of at least one polysiloxane-based binder present in the topcoat composition of the present invention is generally in the range of 200 to 50,000 g / mol, preferably 200 to 10,000, more preferably 400 to 5000 g / mol, most preferably 500 to 2000 g / mol.

[0340] A preferred top coating composition of the present invention comprises 10-95 wt%, more preferably 20-80 wt%, still more preferably 25-60 wt% of a polysiloxane-based binder, based on the total dry weight of the composition.

[0341] The polysiloxane adhesive can be dispersed or emulsified in water. The adhesive can be appropriately chemically modified to improve water compatibility. The dispersion or emulsion may also contain surfactants and emulsifiers to provide water compatibility. In addition, other components may be present, such as stabilizers, defoamers, dispersants and biocides.

[0342] The polysiloxane adhesive may optionally be cured in the presence of a crosslinking agent, which reacts appropriately with the curing active functional groups in the polysiloxane adhesive to form a crosslinked coating when exposed to moisture. The crosslinking agent may also be appropriately used as a base catalyst (base catalyst) for the hydrolysis / condensation reaction.

[0343] Those skilled in the art will understand that a suitable crosslinking agent is selected according to the type of curing active functional group present in the polysiloxane adhesive. If the curing active functional group is a silanol or alkoxy group, the preferred crosslinking agent is an organosilicon compound represented by the following general formula, a partial hydrolysis-condensation product thereof, or a mixture of the two:

[0344] R d -Si-K 4-d

[0345] wherein each R is independently selected from an unsubstituted or substituted monovalent hydrocarbon group of 1 to 6 carbon atoms or a C substituted by a poly(alkylene oxide) 1-6alkyl.

[0346] Each K is independently selected from a hydrolyzable group, such as an alkoxy group; and d is 0, 1 or 2, more preferably 0 or 1.

[0347] Preferred crosslinking agents of this type include tetraethoxysilane, vinyl tri(methylethyloxime)silane, methyl tri(methylethyloxime)silane, vinyl trimethoxysilane, methyl trimethoxysilane and vinyl triisopropenoxysilane and their hydrolysis-condensation products. Suitable crosslinking agents are commercially available, such as Silcate TES-40WN from Wacker and Dynasylan A from Evonik.

[0348] In order to assist the curing process, the polysiloxane top coating composition of the present invention preferably includes a catalyst. Representative examples of usable catalysts include transition metal compounds, metal salts and various metal organic metal complexes, such as tin, iron, lead, barium, cobalt, zinc, antimony, cadmium, manganese, chromium, nickel, aluminum, gallium, germanium, titanium, boron, lithium, potassium, bismuth and zirconium. The salt is preferably a salt of a long-chain carboxylic acid and / or a chelate or an organic metal salt.

[0349] Examples of suitable tin catalysts include, for example, dibutyltin dilaurate, dibutyltin dioctoate, dibutyltin diacetate or dioctyltin dilaurate. Examples of commercially available tin catalysts include BNT-CAT400 and BNT-CAT 500 from BNT Chemicals, FASCAT 4202 from PMC Organometallix, and MetatinKatalysator 702 from DOW.

[0350] Examples of suitable zinc catalysts are zinc 2-ethylhexanoate, zinc naphthenate and zinc stearate.Examples of commercially available zinc catalysts include K-KAT XK-672 and K-KAT670 from King Industries and BorchiKat 22 from Borchers.

[0351] Examples of suitable bismuth catalysts are organic bismuth compounds such as bismuth 2-ethylhexanoate, bismuth octanoate and bismuth neodecanoate. Examples of commercial organic bismuth catalysts are Borchi Kat 24 and Borchi Kat 315 from Borchers, K-KAT XK-651 from King Industries, Reaxis C739E50 from Reaxis and TIBKAT716 from TIB Chemicals.

[0352] The catalyst may also be an organic compound such as triethylamine, guanidine, amidine, cyclic amine, tetramethylethylenediamine, 1,4-ethylenepiperazine and pentamethyldiethylenetriamine. Further examples include aminosilanes such as 3-aminopropyltriethoxysilane and N,N-dibutylaminomethyl-triethoxysilane.

[0353] In a preferred embodiment, the catalyst is a tin, titanium, bismuth, guanidine and / or amidine catalyst, more preferably a tin, titanium, guanidine and / or amidine catalyst.

[0354] Polyurethane adhesive

[0355] The polyurethane-based adhesive used in the present invention preferably comprises: a) a polyisocyanate component and b) a hydroxyl-functional component comprising at least two hydroxyl groups. The crosslinking results from the reaction between the polyisocyanate component a) and the hydroxyl-functional component b).

[0356] Suitable polyisocyanates for use as polyisocyanate component a) in the coating composition are well known in the art. Examples of suitable low molecular weight polyisocyanates having a molecular weight of 168 to 300 g / mol include: hexamethylene diisocyanate (HDI), 2,2,4- and / or 2,4,4-trimethyl-1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, 2,4-diisocyanato-1-methylbenzene (toluene diisocyanate, TDI), 2,4-diisocyanato-1-methylbenzene, 1,4-diisocyanatocyclohexane, l-isocyanato- 3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI), 2,4'- and / or 4,4'-diisocyanato-dicyclohexylmethane, 2,4- and / or 4,4'-diisocyanato-diphenylmethane and mixtures of these isomers with their higher homologues, and any mixtures of these compounds which are obtained in a known manner by phosgenation of aniline / formaldehyde condensates, 2,4- and / or 2,6-diisocyanatotoluene.

[0357] In some preferred topcoats of the present invention, the polyisocyanate component a) is selected from aliphatic polyisocyanates, for example, hexamethylene diisocyanate (HDI), 2,2,4- and / or 2,4,4-trimethyl-1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, 1,4-diisocyanatocyclohexane, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI), 2,4'- and / or 4,4'-diisocyanato-dicyclohexylmethane and 2,4- and / or 4,4'-diisocyanato-diphenylmethane.

[0358] In other preferred topcoats according to the invention, the polyisocyanate component a) is selected from aromatic polyisocyanates, for example 2,4-diisocyanato-1-methylbenzene (toluene diisocyanate, TDI), 2,4-diisocyanato-1-methylbenzene and mixtures of these isomers with their higher homologues, and any mixtures of these compounds which are obtained in a known manner by phosgenation of aniline / formaldehyde condensates, 2,4- and / or 2,6-diisocyanatotoluene.

[0359] In preferred topcoats of the present invention, the polyisocyanate component a) is a derivative of the above-mentioned monomeric polyisocyanates, as is conventional in the art. These derivatives include polyisocyanates containing biuret groups. Examples of particularly preferred derivatives include N, N', N"-tri-(6-isocyanatohexyl)-biuret and mixtures thereof with its higher homologues, and N, N', N"-tri-(6-isocyanatohexyl)-isocyanurate and mixtures thereof with its higher homologues containing more than one isocyanurate ring.

[0360] Examples of suitable commercially available polyisocyanates are:

[0361] From Covestro 2858XP, XP2451 / 1, XP2547, XP2655, 7959, N3400,

[0362] Easaqua from VENCOREX TM M 502, Easaqua TM L 600, Easaqua TM XD 401, Easaqua TM XD 803, Easaqua TM XD 870、Tolonate TM X-Flo 100, Tolonate TM HDT-LV, Tolonate TM HDT-LV2.

[0363] In a preferred option, the polyisocyanate component a) is a prepolymer or a semi-prepolymer.

[0364] Prepolymers and semi-prepolymers can be prepared from: polyols such as ethylene glycol, propylene glycol, trimethylolpropane, 1,6-dihydroxyhexane; low molecular weight hydroxyl-containing esters of these polyols with dicarboxylic acids; low molecular weight ethoxylation and / or propoxylation products of these polyols; and mixtures of the above-mentioned multivalent modified or unmodified alcohols.

[0365] Preferably, the prepolymers and semi-prepolymers are prepared from relatively high molecular weight polyols having at least two hydroxyl groups per molecule.

[0366] The polyether polyols are also suitable for preparing prepolymers and semi-prepolymers containing isocyanate groups.

[0367] Hydroxyl-containing polycarbonates are also suitable for preparing prepolymers and semi-prepolymers.

[0368] Preferably, the hydroxy-functional component b) is based wholly or partly on organic polyols and comprises both low molecular weight polyols and relatively high molecular weight polyols.

[0369] Particularly preferred hydroxy-functional isocyanate-reactive compounds which can be used as component b) are the hydroxy-functional polyacrylates known for use in polyurethane coatings. The copolymers are based on hydroxyl-containing olefin monomers and hydroxyl-free olefin monomers. Examples of suitable monomers include vinyl and vinylidene monomers such as styrene, α-methylstyrene, o- and p-chlorostyrene, o-, m- and p-methylstyrene, p-tert-butylstyrene; acrylic acid; (meth)acrylonitrile; acrylic acid and methacrylic acid esters of alcohols containing 1 to 8 carbon atoms, such as ethyl acrylate, methyl acrylate, n-propyl acrylate and isopropyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, isooctyl acrylate, methyl methacrylate, ethyl methacrylate, methyl methacrylate, butyl acrylate and isooctyl methacrylate; diesters of fumaric acid, itaconic acid or maleic acid having 4 to 8 carbon atoms in the alcohol component; (meth)acrylamide; vinyl esters of alkane monocarboxylic acids having 2 to 5 carbon atoms, such as vinyl acetate or vinyl propionate; and hydroxyalkyl esters of acrylic acid or methacrylic acid having 2 to 4 carbon atoms in the hydroxyalkyl group, such as 2-hydroxyethyl-, 2-hydroxypropyl-, 4-hydroxybutyl-acrylate and methacrylate and trimethylolpropane-mono- or pentaerythritol mono-acrylate or methacrylate. Mixtures of the aforementioned monomers can also be used to prepare hydroxy-functional polyacrylates. Mixtures of the polyols described above can also be used as component b).

[0370] In preferred polyurethane-based adhesives, components a) and b are used in amounts sufficient to provide an equivalent ratio of isocyanate groups to isocyanate-reactive (hydroxyl) groups of 0.5:1 to 5:1, preferably 0.8:1 to 2:1, more preferably 0.8:1 to 1.5:1, even more preferably 0.8:1 to 1.2:1. The hydroxy-functional compound b) is preferably present in an amount such that up to 20 hydroxyl groups are present.

[0371] The hydroxyl functional compound b) can be dispersed or emulsified in water. The hydroxyl functional compound b) can also contain surfactants, emulsifiers and appropriate chemical modifications to provide water compatibility. In addition, other components such as stabilizers, defoamers, dispersants and biocides may be present.

[0372] The hydroxy-functional compound b) dispersion or emulsion preferably has a water content of 45 to 65 wt. %.

[0373] Examples of suitable commercial hydroxy-functional (isocyanate-reactive) resins include:

[0374] From Covestro A242, A 2058, A 2427, A 2457, A 2470, A 2542, A 2546, A 2601, A 2646, A2651, A2695, A 2845, U XP 2766.

[0375] Antkote 2036 from WANHUA,

[0376] From ALLNEX SM 6810w / 42WA, SM 6817w / 44WA, SM 6825w / 41WA, SM 6826w / 43WA, VSM 2521w / 42WAB, VSM 6299w / 42WA, 37-6517, 6510, 6511, 6514, 6515, 6516, 6522, 8455.

[0377] Catalysts are optionally used with polyurethane adhesives and accelerate the curing reaction. Examples of suitable catalysts include tetramethylbutylene diamine (TMBDA), N-alkylmorpholine, triethylamine (TEA), 1,8-diazabicyclo[5.4.0]undecene-7 (DBU), pentamethyldiethylenetriamine (PMDETA), zinc octanoate, dioctyltin dilaurate, dibutyltin dilaurate, and dibutyltin oxide, particularly dioctyltin dilaurate, dibutyltin dilaurate, and dibutyltin oxide.

[0378] Acrylic adhesive

[0379] Any known acrylic adhesive can be used to prepare the topcoat composition. Acrylic adhesives of general interest are those prepared using one or more monomers such as (meth)acrylic acid or esters, such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxy-1-methylethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate and hydroxyisobutyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxy-1-methylethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate and hydroxyisobutyl (meth)acrylate. meth)acrylate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, tetrahydrofuran (meth)acrylate, isopropylidene glyceryl (meth)acrylate, glyceryl formal (meth)acrylate, cyclic trimethylolpropane formal (meth)acrylate, hydroxyethyl (meth)acrylate, glycidyl (meth)acrylate and 4-glycidyloxybutyl (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)acrylic acid.

[0380] The acrylic adhesive used in the top coating composition can be an adhesive based on a monomer 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-butylene glycol di(meth)acrylate, 1,4-butylene glycol 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.

[0381] These monomers can be combined with other non-acrylic monomers to prepare the desired polymer, such as styrene.

[0382] Acrylic adhesives can be dispersed or emulsified in water. The adhesive can be appropriately chemically modified to improve water compatibility. The dispersion or emulsion can also contain surfactants and emulsifiers to provide water compatibility. In addition, other components such as stabilizers, defoamers, dispersants and biocides can be present.

[0383] The acrylic adhesive dispersion or emulsion preferably has a water content of 45 to 65 wt %.Any aqueous acrylic adhesive may be used in the topcoat composition.

[0384] Examples of suitable commercially available acrylic adhesives are:

[0385] From ALLNEX 6301, 6302, 6719, 6754, 6756, 6774, 6776, 6781, ECO 6778, ECO 6788, ECO6794, ECO 9000, ECO 9415, B 1181, B 3009, B 3010, B 3014, B3022, B 3033, B 746, B 976, BMR 47, SC 6805w / 50WA, SC 6841w / 50WA, VSC6254w / 40WA, VSC 6265w / 40WA, VSC 6279w / 45WA, VISCOPOL TM 9898、VISCOPOL TM ECO 2085, PRIMAL from Dow TM SF-016ER、PRIMAL TM P-308、PRIMAL TM MV-24, PRIMAL TM ECO-16, PRIMAL TM AC-339、PRIMAL TM E-357EF、PRIMAL TM HG-415、PRIMAL TM 928ER、PRIMAL TM S-920、PRIMAL TM AS-8000、PRIMAL TM EC-1791、PRIMAL TM WDV-3317E、PRIMAL TM ECO-46, PRIMAL TM SS-521EF、PRIMAL TM SS-640、PRIMAL TM UC-550EF、PRIMAL TM 3317EF、PRIMAL TM AS-8012CN、PRIMAL TM AS-8012R、PRIMAL TM AC-285.

[0386] The topcoat composition may comprise at least 30% by dry weight of a binder polymer, such as at least 40% by dry weight of a binder.

[0387] The topcoat composition may also contain standard additives such as pigments and fillers, thickeners, dispersants and biocides. Suitable pigments and fillers include titanium dioxide, zinc oxide, aluminum oxide, barium sulfate, carbonates, borates, silica, silicates, heavy metal oxides such as cerium oxide, lanthanum oxide and zirconium oxide, mica, diatomaceous earth and bentonite. The preferred filler is barium sulfate.

[0388] The filler preferably constitutes from 1% to 25% by dry weight of the intumescent coating composition.

[0389] It is noteworthy that the water-based topcoat of the present invention is compatible with the water-based epoxy intumescent coating of the present invention. Although water-based acrylic topcoats have previously been shown to be compatible with melamine formaldehyde resins, such resins have very different chemistry than epoxy resins. For example, melamine formaldehyde resins contain a large number of amine groups, which of course affects compatibility with the topcoat.

[0390] We have demonstrated in the examples that vinyl acetate based intumescent coatings are not compatible with acrylic topcoats, so compatibility is clearly an issue. It is noteworthy that the waterborne topcoats defined herein have good compatibility with waterborne epoxy intumescents.

[0391] The invention will now be described with reference to the following non-limiting examples.

[0392] Analytical methods

[0393] General procedure for preparing compositions

[0394] The components of the intumescent coating composition are mixed in the specified weight portions on a high-speed dissolver. The resin is added first and blended at a low speed. Additives, intumescent pigments and fillers are then added and mixed at a high speed until no lumps are visible. Components A and B are prepared separately. Intumescent pigments, fillers and additives are present only in component A. Components A and B are mixed in a weight ratio between 2:1 and 5:1.

[0395] The total amount of each component in the coating composition after mixing components A and B is listed in the following table.

[0396] Fire test

[0397] The fire protection test was a vertical plate test following the BS 476 Cellulose heating curve using 2 K-type thermocouples on each steel substrate. The substrates were 30 x 30 x 0.6 cm and 6 samples were tested simultaneously. The test results were recorded as the time in minutes before the steel substrate reached a critical core temperature of 550°C.

[0398] Determination of the solid content of the composition

[0399] The solid content of the composition was calculated according to ASTM D5201-05.

[0400] Calculation of Volatile Organic Compound (VOC) Content of Coating Compositions

[0401] The volatile organic compound (VOC) content of the coating composition was calculated according to ASTM D5201-05.

[0402] Durability Test

[0403] Durability was evaluated by comparing the fire test results of the exposed samples with those of the unexposed samples. The exposed samples were placed in a south-facing rack for 8 weeks from October to December. After exposure, they were conditioned indoors for 2 weeks before the fire test.

[0404] Curing time

[0405] The curing time is recorded with a Beck and Koller drying time machine, in which several stages of drying time are recorded. The coating sample is applied to the glass strip with a standard wet film thickness using a frame applicator. The machine moves one end of a metal rod through the wet coating film, and the machine is programmed to spend 6 or 12 or 24 or 48 hours to move through the length of the drawdown. The curing time is selected as the time when the coating no longer shows signs of the steel rod passing, which is called T3 in the non-standard test method.

[0406] Top coating appearance

[0407] The topcoat is applied on top of the intumescent layer according to the application guidelines for the topcoat product. A score of 1 is given if the cured film of the topcoat has no visible defects, a score of 2 is given if there are pinholes or small cracks less than 1% of the surface, a score of 3 is given if there is 1 to 10% cracking, a score of 4 is given if there is 11 to 60% cracking, or a score of 5 is given if more than 60% of the surface is cracked.

[0408] Example 1

[0409] The following materials were used:

[0410] Table 1

[0411]

[0412] 1 Becopox EP2375 from Allnex, 2 Beckopox EP387 from Allnex, 3 Araldite GY776 CH from Huntsman. 4 Beckcure EH 2100 from Allnex, 5 Aradur3985DB from Huntsman, 6 Coadis BR85 from Coatex, 7 Texanol from Eastman.

[0413] In Table 2 the prepared compositions are explained.

[0414] Table 2 - Part A

[0415]

[0416] Table 2 Part B

[0417] type Wt%B1 Wt%B2 Wt%B3 Amine curing agent 1 (44 wt.%, in water) 100％ 100％ Amine curing agent 2 (55 wt.%, in water) 100％ Water content (wt.%) 56 56 45

[0418] The A and B components were mixed before application in the mixing ratios given in Table 3 below. The intumescent coating composition was applied to steel panels having an epoxy primer layer (Muki EPS from Jotun, thickness 40 to 90 μm) thereon. The steel panels were 0.6 cm thick and had dimensions of 30 x 30 cm. The drying times are reported in Table 3 below.

[0419] The two-coat system was then subjected to fire protection tests and outdoor exposure tests.As a comparison, a commercially available waterborne intumescent coating comprising a binder based on vinyl acetate was used.

[0420] Table 3

[0421]

[0422] Example 2

[0423] The 2-layer coating system of Example 1 was further coated using a topcoat composition, Pilot WF from Jotun AS, which is water-based and contains, inter alia, an acrylic binder. This topcoat composition is used commercially in combination with solvent-based or solvent-free intumescent coating compositions, but cannot be used in combination with water-based vinyl acetate-based intumescent coatings due to incompatibility issues as shown below. The appearance of the three-layer system was evaluated.

[0424] System properties: Table 4

[0425]

[0426] The intumescent coating system of the present invention provides a crack-free coating system formed from a water-based coating formulation.

Claims

1. A method for applying an intumescent coating system to a substrate, comprising: (I) applying to a substrate an intumescent coating composition comprising: i. 10 to 30% by dry weight of an epoxy adhesive; ii. Curing agent; iii. 1.0 to 15% by dry weight of a bulking agent; iv. 12 to 40% by dry weight of an acid-generating compound; v. 1.0 to 15% by dry weight of a carbon donor compound; and vi. 10 to 30 wt% water; and curing the composition to form an intumescent coating; (II) applying a top coating composition to the cured or partially cured intumescent coating to form a top coating, the top coating composition comprising an acrylic binder or a polyurethane binder and at least 10 wt.% of water, The intumescent coating composition is waterborne and the topcoat composition is waterborne.

2. The method according to claim 1, wherein the substrate to which the intumescent coating composition is applied is provided with a primer layer.

3. The method of claim 1, wherein the topcoat composition comprises an acrylic binder.

4. The method of claim 1, wherein the curing agent is an aliphatic amine.

5. The method of claim 4, wherein the aliphatic amine is an aliphatic polyamine.

6. The method of claim 1, wherein the carbon donor compound is pentaerythritol, dipentaerythritol or tripentaerythritol.

7. The method of claim 1, wherein the acid generating compound is ammonium polyphosphate.

8. The method according to claim 1, wherein the swelling agent is melamine or a melamine derivative.

9. The method of claim 1, wherein the topcoat composition is cured.

10. An intumescent coating system obtained by the method according to any one of claims 1 to 9, comprising: B) Intumescent coating; C) Top coating; Wherein, the intumescent coating comprises: i. Epoxy adhesives; ii. Curing agent; iii. Bulking agent; iv. acid generating compounds; and v. Carbon donor compound, Wherein, the top coating layer comprises an acrylic adhesive or a polyurethane adhesive.

11. An intumescent coating system obtained by the method of claim 2, comprising an intumescent coating system comprising: A) Primer layer; B) Intumescent coating; C) Top coating; in, The primer layer comprises an epoxy adhesive or a vinyl adhesive; Wherein, the intumescent coating comprises: i. Epoxy adhesives; ii. Curing agent; iii. Bulking agent; iv. acid generating compounds; and v. Carbon donor compound, Wherein, the top coating layer comprises an acrylic adhesive or a polyurethane adhesive.

12. An intumescent coating system according to any one of claims 10 to 11, wherein the topcoat comprises an acrylic binder.

13. The intumescent coating system according to any one of claims 10 to 11, wherein the top coat is free of intumescent components.

14. A substrate coated with an intumescent coating system obtainable by the process of any one of claims 1 to 9.

15. Use of an intumescent coating system according to any one of claims 10 to 13 for coating a substrate.

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