Intumescent coating composition

Abstract

The present application relates to an intumescent coating composition comprising: (a) an epoxy resin having one or more alkylene moieties in the backbone, all selected from divalent alkane groups of formula # imgabs0 # wherein Ra and Rb are each independently H, OH or an aromatic group and z is an integer from 1 to 8, and / or a divalent cyclic alkane group; (b) an alkylene di (meth) acrylate in which the alkylene group has 4, preferably 5 or more carbon atoms; (c) a curing agent; and (d) a compound that provides an expansion gas upon thermal decomposition. In addition, the present application also relates to a method of coating a substrate and a substrate at least partially coated with a coating deposited from the coating composition.

Description

Field of the Invention

[0001] The present disclosure relates to an intumescent coating composition, particularly an intumescent coating composition comprising an epoxy resin. Background Art

[0002] Many materials (such as steel) rapidly lose their strength and fail in fire. The structural collapse of "high-rise" office buildings, oil and gas facilities or other infrastructure due to fire, as well as the rupture of processing containers or pipeline structures, can be catastrophic in terms of accident escalation, property damage and even loss of life.

[0003] Intumescent coatings are used on many structures to delay the effects of fire. These structures include profiles, cold-rolled steel, concrete, wood, aluminum, mixed metals, plastic substrates and batteries. Intumescent coatings generally contain some form of resin binder, such as a high-temperature polymer, such as an epoxy resin and a suitable crosslinking agent. The resin binder forms a hard coating. If an epoxy resin is present in the binder, the binder also provides a carbon source, and the carbon is converted to char upon combustion.

[0004] Bisphenol A, also known as BPA, and epoxy resins formed therefrom, such as bisphenol A type epoxy resins formed by condensation thereof with epichlorohydrin under alkaline conditions, are used as resin binders for coatings in some prior art intumescent coating solutions. However, it has been found that the fire resistance of BPA type epoxy resins and intumescent coatings based on such epoxy resins is difficult to further improve and often causes sagging of the fireproof coating.

[0005] Therefore, the object of the present disclosure is to provide an intumescent coating composition for fire protection, which should exhibit better fire protection performance and mechanical properties compared to intumescent coating compositions based on bisphenol A epoxy resins.

[0006] Summary

[0007] These and other objects can be achieved by an intumescent coating composition comprising:

[0008] (a) an epoxy resin having one or more alkylene moieties in the main chain, all of the alkylene moieties being selected from divalent alkane groups of the formula wherein Ra and Rb are each independently H, OH or an aromatic group and z is an integer from 1 to 18, such as 1 to 8, and / or selected from divalent cycloalkane groups;

[0009] (b) an alkylene di(meth)acrylate, wherein the alkylene moiety has 4, preferably more than 5 carbon atoms;

[0010] (c) a curing agent; and

[0011] (d) A compound that provides expanding gas upon thermal decomposition; wherein

[0012] Compounds (a) to (d) are different from each other.

[0013] The present disclosure further relates to a method of coating a substrate, the method comprising applying an intumescent coating composition according to the present disclosure to the substrate.

[0014] In addition, the present disclosure also relates to a substrate at least partially coated with a coating deposited from an intumescent coating composition according to the present disclosure.

[0015] It has been found that the intumescent coating composition according to the present disclosure can provide better char-forming properties and better sag resistance compared to other structures, especially epoxy resins having a branched alkylene moiety with an aliphatic side chain, such as bisphenol A epoxy resin. At the same time, the intumescent coating composition according to the present disclosure has a lower viscosity, and thus is more suitable for spraying when formulated into a solvent-free system, and has better atomization, so that the paint film formed after spraying the composition has a better appearance. In addition, the intumescent coating composition according to the present disclosure can also have better flexibility compared to an intumescent coating based on an epoxy resin having a branched alkylene moiety with an aliphatic side chain in the main chain, such as bisphenol A epoxy resin.

[0016] Details

[0017] The intumescent coating composition according to the present disclosure comprises

[0018] (a) An epoxy resin having one or more alkylene moieties in the main chain, all of the alkylene moieties being selected from divalent alkane groups of the formula wherein Ra and Rb are each independently H, OH or an aromatic group and z is an integer from 1 to 18, such as an integer from 1 to 8, and / or selected from divalent cycloalkane groups;

[0019] (b) Alkylene di(meth)acrylate, wherein the alkylene has 4 carbon atoms, preferably more than 5 carbon atoms;

[0020] (c) A curing agent; and

[0021] (d) A compound that provides expanding gas upon thermal decomposition.

[0022] Those skilled in the art know that the so-called "epoxy resin" refers to an epoxy resin or epoxy polymer having an average of more than one, preferably two or more epoxy groups per molecule, which is preferably a liquid epoxy resin or a solid epoxy resin.

[0023] Examples of epoxy resins include polyglycidyl ethers derived from polyols such as ethylene glycol, diethylene glycol, triethylene glycol, bisphenol A, hydrogenated bisphenol A, bisphenol F, hydrogenated bisphenol F, or polyether diols such as poly(tetramethylene oxide) glycol, poly(ethylene oxide) glycol, poly(propylene oxide) glycol.

[0024] In addition, epoxy resins can also include polyglycidyl ethers of polycarboxylic acids, which are formed by the reaction of epoxides such as epichlorohydrin with aliphatic or aromatic polycarboxylic acids such as oxalic acid, succinic acid, glutaric acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, or dimerized linoleic acid.

[0025] Other examples of epoxy resins include epoxidized ethylenically unsaturated alicyclic materials such as epoxy alicyclic ethers and esters, epoxy resins containing oxiranyl groups, epoxy novolak resins, which are prepared by reacting epihalohydrin with the condensation product of an aldehyde and a mono- or poly-phenol (such as epoxy phenol novolak resin or epoxy cresol novolak resin).

[0026] Flexible polyepoxy resins are also often used in intumescent coating compositions, such as epoxidized soybean oil, dimer acid-based materials, and rubber-modified polyepoxy resins, such as products prepared from polyglycidyl ethers of bisphenol A and acid-functional polybutadiene.

[0027] Other commonly used polyepoxides also include, for example, epoxy-functional adducts prepared from flexible acid-functional polyesters and polyepoxides, and epoxy-functional acrylic resins, etc.

[0028] The intumescent coating composition of the present disclosure is epoxy resin-based, which means that the binder of the coating is substantially composed of epoxy resin, for example, at least 90 wt%, at least 95 wt%, at least 98 wt%, or at least 99 wt% or all composed of epoxy resin, based on the total weight of the binder of the coating.

[0029] However, as described above, in the intumescent coating composition of the present disclosure, an epoxy resin having one or more alkylene moieties in the main chain and all of the alkylene moieties defined as above must be included. Advantageously, the epoxy resin having one or more of the alkylene moieties in the main chain constitutes the major amount of the epoxy resin binder in the intumescent coating composition of the present disclosure. For example, based on the total weight of the epoxy resin binder, at least 90 wt%, at least 95 wt%, at least 98 wt%, or at least 99 wt% or all of the epoxy resin is composed of the epoxy resin having one or more of the alkylene moieties in the main chain.

[0030] In the context of the present application, the "main chain" of the epoxy resin refers to the part of the epoxy resin after removing all epoxy groups such as epoxy groups (epoxyethyl) or glycidyloxy groups, and can be a substituted or unsubstituted divalent or polyvalent hydrocarbon group optionally having ether oxygen atoms.

[0031] The epoxy resin according to the present disclosure should have one or more alkylene moieties in the main chain, provided that all alkylene moieties are selected from the divalent alkane groups of the formula where Ra and Rb are each independently H, OH or an aromatic group and z is an integer from 1 to 18, such as 1 to 12 or 1 to 8, such as 1, 2 or 3, or selected from divalent cycloalkane groups. In other words, all alkylene moieties in the main chain of the epoxy resin according to the disclosure should be linear or straight-chain alkylene groups substituted only by OH or aromatic groups, or cycloalkylene groups. Therefore, by this definition, there should be no other forms of alkylene in the main chain of the epoxy resin (a) according to the present disclosure, such as alkylene moieties having aliphatic side chains such as

[0032] The "alkylene" represents a divalent form of an alkane group, and the "alkylene moiety" can be regarded as a part or segment having an alkylene group, which forms two connecting bonds at both ends to connect non-alkylene moieties of different natures such as ether oxygen, glycidyloxy or aromatic groups (such as phenyl).

[0033] The "alkyl" or "alkylene" is derived from an alkane, which is a compound in which all carbon atoms in the molecule are connected by carbon-carbon single bonds and the remaining valence bonds are combined with hydrogen. The alkane can have, for example, 1 to 30, such as 2 to 20 or 3 to 18 or 4 to 12 carbon atoms. Generally, the alkane can have a straight-chain (linear), branched-chain or cyclic structure. The branched-chain alkane can also be regarded as a form in which an alkyl group is substituted on the straight-chain alkane. The cyclic alkane can have at least 3, such as 4, 5 or 6 carbon atoms, and can have 1, 2, 3 or more rings. As examples of alkanes, methane, ethane, propane, cyclopropane, butane, cyclobutane, pentane, cyclopentane, hexane, cyclohexane, heptane, etc. can be cited. In the present application, the alkane can also include its halogen (such as F, Cl or Br) substituted forms.

[0034] The "aryl" or "aromatic group" represents a group formed by removing one or more hydrogen atoms from the aromatic nucleus carbon of an aromatic hydrocarbon (arene) having a ring structure. The arene usually has more than 5 carbon atoms, such as 6 - 30 or 7 - 20 carbon atoms. Examples of arenes can include phenyl, methylphenyl, ethylphenyl, biphenyl, etc. In the present application, the arene can include its alkyl or halogen (such as F, Cl or Br) substituted forms.

[0035] The alkylene moiety can be of the formula a divalent alkane group, where Ra and Rb are each independently H or phenyl, preferably H, and z is an integer from 1 to 6, preferably from 1 to 4. Advantageously, the alkylene moiety includes a methylene group (-CH2-) that bridges two aromatic groups such as phenyl groups at both ends.

[0036] The epoxy resin that may have one or more of the alkylene moieties in the main chain may have the formula X-(G)n, where G represents glycidyloxy, X represents an n-valent hydrocarbon group that has one or more of the alkylene moieties, optionally one or more ether oxygen atoms, and optionally one or more aromatic groups, or may also be composed of them, and n represents an integer greater than or equal to 2, such as 2 - 30, 3 - 20, 3 - 10, or 2 - 6, or preferably 2, 3, or 4. X can be regarded as the main chain of the epoxy resin.

[0037] The main chain X may include the alkylene moiety, (poly)oxyalkylene composed of the alkylene moiety and one or more ether oxygen atoms, or a structural unit composed of the alkylene moiety (especially a divalent alkane group of the formula and aromatic groups (such as phenyl or methylphenyl) connected at both ends), or a mixture thereof; or the main chain X is composed of them.

[0038] Examples of suitable epoxy resins of the formula X-(G)n include polyglycidyl ethers derived from polyols, the polyols including alkane polyols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2 - propanediol, 1,4 - butanediol, 1,5 - pentanediol, 1,6 - hexanediol, 1,2,6 - hexanetriol, cyclohexanedimethanol, glycerol, trimethylolpropane, bisphenol F, hydrogenated bisphenol F, or polyether diols, and also epoxy phenol novolac resins or epoxy cresol novolac resins; preferably, including bisphenol F type epoxy resins, epoxy phenol novolac resins, epoxy cresol novolac resins, 1,6 - hexanediol diglycidyl ether, and 1,4 - butanediol diglycidyl ether; more preferably, including bisphenol F type epoxy resins, epoxy phenol novolac resins, or epoxy cresol novolac resins.

[0039] The epoxy resin based on bisphenol F (also known as bisphenol F type epoxy resin or diglycidyl ether of bisphenol F, abbreviated as BPF) can be prepared by reacting phenol with formaldehyde under acidic catalysis to form bisphenol F, and then carrying out a polycondensation reaction with epichlorohydrin under alkaline conditions.

[0040] Specifically, the bisphenol F epoxy resin may have the structure of formula (I):

[0041]

[0042] Here, the substituents R' and R” are each independently H.

[0043] In solid epoxy resins, the exponent s has a value > 1.5, in particular 2 - 12. Compounds of formula (II) with an exponent s of 1 to 1.5 are semi-solid epoxy resins. In liquid epoxy resins, the exponent s has a value less than 1.

[0044] The bisphenol F-based epoxy resins suitable for the present disclosure are commercially available, for example, KUKDO YDF-170 from Kukdo Chemical.

[0045] Phenol novolac epoxy resins can also be used, which include so-called epoxy phenol novolac resins or epoxy cresol novolac resins. These in particular have the following formula:

[0046] where or CH 2， R1 = H or methyl and y = 0 to 7.

[0047] More particularly, these are phenol or cresol epoxy linear novolac resins (R2 = CH2).

[0048] These epoxy resins are also commercially available, for example, obtained as Epikote170 from Momentive Specialty Chemicals.

[0049] The epoxy resins having one or more of said alkylene moieties in the main chain may be bisphenol F-based epoxy resins, phenol novolac epoxy resins or a mixture of both. It has been found that much better fire protection properties and mechanical properties can be obtained when the epoxy resins contain these compared to intumescent coating compositions based on bisphenol A epoxy resins.

[0050] The content of the epoxy resin having one or more of said alkylene moieties in the main chain is in the range of 8 - 40% by weight, preferably 12 - 30% by weight, based on the total weight of the coating composition.

[0051] The intumescent coating composition according to the present disclosure may not contain bisphenol A epoxy resin.

[0052] The intumescent coating composition according to the present disclosure may further contain component (b) alkylene di(meth)acrylate, wherein the alkylene has 4 carbon atoms, preferably more than 5 carbon atoms.

[0053] Specifically, the alkylene di(meth)acrylate can be represented as R(A)2, where R represents an alkylene having 4 carbon atoms, for example more than 5 carbon atoms, such as 6 - 12 or 6 - 10, and A represents a (meth)acrylate group.

[0054] In the alkylene di(meth)acrylate, the alkylene is preferably straight-chain. The alkylene di(meth)acrylate may not have a hydroxyl-substituted functional group.

[0055] Alkylene di(meth)acrylates suitable for use in the compositions of the present disclosure include, for example, pentanediol di(meth)acrylate, hexanediol di(meth)acrylate, heptanediol di(meth)acrylate, octanediol di(meth)acrylate, nonanediol di(meth)acrylate, decanediol di(meth)acrylate, dodecanediol di(meth)acrylate, with hexanediol di(meth)acrylate being preferred.

[0056] Such alkylene di(meth)acrylates are known per se or can be obtained by known methods of preparation. For example, the desired alkylene di(meth)acrylate can be prepared by reacting (meth)acrylic acid with the corresponding R-group-based diol in a suitable ratio. They are also commercially available, for example ALLNEX HDDA from Allnex.

[0057] In the intumescent coating composition of the present disclosure, the content of component (b) alkylene di(meth)acrylate can be in the range of 5-20% by weight, preferably 7-15% by weight, based on the total weight of the coating composition. It has been found that alkylene di(meth)acrylate can not only reduce the viscosity of the solventless coating, but also better penetrate into the epoxy / amine curing system, while providing good flexibility to the curing system. In addition, it has been found that the epoxy resin system including alkylene di(meth)acrylate can achieve better thermal stability at high temperatures and make the melt viscosity of the paint film relatively high, thereby avoiding sagging at high temperatures.

[0058] The intumescent coating composition according to the present disclosure may further include a curing agent (c) having a plurality of functional groups reactive with the epoxy groups of the epoxy resin and the (meth)acrylate groups of component (b). Curing can be carried out at ambient temperature or upon heating. The curing agent (c) can be selected from polyamine functional compounds, polythiol compounds, and combinations thereof.

[0059] The polyamine curing agents can be selected from aliphatic polyamines, aromatic polyamines, polyamides, polyetheramines, such as those commercially available from Huntsman Corporation, The Woodlands, Texas, polysiloxane amines, polysulfide amines, or combinations thereof. Examples include diethylenetriamine, 3,3-aminobipropylamine, triethylenetetramine, tetraethylenepentamine, cyclohexanedimethanamine (1,2-BAC), m-xylenediamine (MXDA), and reaction products of polyamines with aliphatic fatty acids, such as a series of materials sold by BASF under the trademark VERSAMID can be used.

[0060] The polythiol compound may be selected from polysulfide thiols, polyether thiols, polyester thiols, pentaerythritol-based thiols; or combinations thereof. Examples of polythiol compounds useful in the intumescent coating composition include G4, commercially available from Akzo Nobel Functional Chemicals GmbH & Co KG, Greiz, Germany.

[0061] In the intumescent coating composition, the equivalent ratio of the combined epoxy and (meth)acrylate groups to the functional groups in component (c) may be from 2:1 to 1:2.

[0062] The intumescent coating composition further comprises a compound which provides an expanding gas upon thermal decomposition as component (d).

[0063] When exposed to a high temperature flame, the expanding gas serves to foam and expand the fire intumescent composition. Due to this expansion, the char formed is a thick, porous material which serves to insulate and protect the underlying substrate. Sources of expanding gas which may be used in the intumescent coating composition of the present disclosure are nitrogen-containing materials. Examples of suitable nitrogen-containing materials include melamine, salts of phosphoric acid, guanidine, hydroxymethylated melamine, hexamethoxymethyl melamine, urea, dimethylurea, melamine pyrophosphate, dicyandiamide, guanylurea phosphate and glycine. Suitably, melamine is used. Other conventional sources of expanding gas may also be used, such as those which release carbon dioxide. Examples are alkaline earth metals, such as calcium carbonate or magnesium carbonate. Compounds which release water vapor upon decomposition upon heating may also be used, such as calcium hydroxide, magnesium dihydroxide or aluminum trihydroxide. Other examples of such compounds are boric acid and boric acid derivatives.

[0064] In the intumescent coating composition of the present disclosure, the amount of component (d) may range from 0.1 to 25% by weight, suitably from 1 to 10% by weight, where the weight percentages are based on the total solids weight of the composition.

[0065] The intumescent coating composition of the present disclosure may optionally comprise an additive (f) selected from phosphorus sources, boron sources, zinc sources, acid sources, carbon sources, inorganic fillers, mineral fibers such as CHOPVANTAGE commercially available from PPG, Coatforce or Roxul fibers commercially available from Lapinus, rheology additives, organic solvents, pigments, foam stabilizers and combinations thereof.

[0066] In addition, the intumescent coating composition of the present disclosure may comprise an epoxy-amine curing catalyst, such as that available from Evonik Industries, Marl, Germany K54 or styrenated phenol such as Kumanox 3110F commercially available from KUMHOPETROCHEMICAL. Based on the total weight of the coating composition, the amount of the curing catalyst can be from 0.1 to 7 wt%, more suitably from 1 to 5 wt%.

[0067] The source of phosphorus can be selected from a variety of materials such as phosphoric acid, monoammonium and diammonium phosphates, tris(2-chloroethyl) phosphate, phosphorus-containing amides such as phosphoramides and melamine pyrophosphate. Suitably, the source of phosphorus is ammonium polyphosphate represented by the formula (NH4) n+2 P n O 3n+1 wherein n is an integer of at least 2, suitably n is an integer of at least 50. Based on the total solids weight of the coating composition, the present disclosure can include from 0 to 20 wt%, suitably from 0.5 to 10 wt% of phosphorus. It is believed that phosphorus acts as a char promoter in the intumescent composition.

[0068] The optional source of zinc can be selected from a variety of materials. It is believed that zinc materials contribute to the formation of a microporous structure in the char. The micropores in the char provide better thermal insulation of the substrate and are able to better retain the integrity of the char and adhere to the substrate, even in the absence of external reinforcing materials. Thus, cracking of the char and its detachment from the substrate are minimized, and better protection is provided to the underlying steel. Examples of suitable materials as the zinc source include zinc oxide, zinc salts such as zinc borate and zinc phosphate, zinc carbonate, and zinc metal. Suitably, zinc borate is used. Based on the total solids weight of the composition, the intumescent coating composition of the present disclosure can include from 0 to 25 wt%, suitably from 0.5 to 12 wt% of zinc.

[0069] The source of boron can be selected from ammonium pentaborate or zinc borate, boron oxide, borates such as sodium borate, potassium borate and ammonium borate, borate esters such as butyl borate or phenyl borate and combinations thereof. The intumescent coating composition of the present disclosure can include from 0 to 10 wt%, suitably from 1 to 6 wt% of boron, wherein the weight percentage is based on the total solids weight of the composition.

[0070] The acid source can be selected from ammonium phosphate, ammonium polyphosphate, diammonium diphosphate, diammonium pentaborate, phosphoric acid generating materials, boric acid, metals or organic borate / salts and combinations thereof.

[0071] The carbon source can be selected from (i) polyhydroxy compounds such as pentaerythritol, dipentaerythritol, glycerol, oligoglycerol, xylitol, mannitol, and sorbitol; and (ii) polymers such as polyamides, polycarbonates, polyurethanes and combinations thereof.

[0072] Phosphorus, zinc, boron, and the compound that provides expanding gas upon thermal decomposition can each be provided by separate source materials, or alternatively, a single material can be the source of more than one of the additional components listed above. For example, melamine pyrophosphate can provide the source of both phosphorus and expanding gas.

[0073] Optional reinforcing fillers can be selected from a large number of commonly used materials, including fiber-reinforcing materials and flake-reinforcing materials, which are more suitable than other fillers. Examples of fiber-reinforcing materials include glass fibers, ceramic fibers such as alumina / silica, and graphite fibers. Flake-reinforcing materials include hammer mill glass flake, mica, and wollastonite. Other suitable fillers include metal oxides, titanium oxide, clay, talc, silica, diatomaceous earth, fibers commercially available from Lapinus, and various pigments. It is believed that the reinforcing fillers help control the expansion of the intumescent coating composition before and during char formation, resulting in a hard and uniform char. When present, the reinforcing filler is typically present in the composition in an amount of 1 to 50% by weight based on the total solid weight of the intumescent coating composition.

[0074] The intumescent coating composition of the present disclosure may also contain a variety of conventional additives, such as rheology additives, organic solvents, foam stabilizers, pigments, flame spread control agents, etc. These components are optional and can be added in different amounts.

[0075] The intumescent coating composition can be configured as a two-part system, where component (a) and possibly other epoxy resins, and component (b) alkylene di(meth)acrylate are in the first package (A), while the curing agent component (c) is in the second package (B), where the compound (d) that provides expanding gas upon thermal decomposition and any additive (f) (if present) are included in package (A) or package (B) in any combination, or in both, or in one or more other packages (C). Before using the intumescent coating composition, the individual packages are mixed.

[0076] The described intumescent coating composition can be in the form of a thick material such as a paste-like putty. Solventless and sprayable compositions are particularly suitable. In the present disclosure, the "solventless" or "solventless coating" means that based on the entire intumescent coating composition, the amount of organic solvent contained in the coating does not exceed 1% by weight, preferably does not exceed 0.5% by weight, more preferably does not exceed 0.1% by weight, particularly does not exceed 0.05% by weight, or contains no organic solvent at all.

[0077] The intumescent coating composition of the present disclosure can be applied to a variety of substrates, particularly steel substrates, and does not crack when subjected to extreme temperature changes in a short period of time. The intumescent coating composition of the present disclosure has good flexibility and is particularly suitable for the protection of cellulose fire and hydrocarbon fire steel structures. The intumescent coating composition may not require the addition of a mesh. These meshes are usually fiber meshes applied to prevent cracking, such as meshes of carbon fiber or glass fiber.

[0078] The following examples are intended to illustrate the present disclosure and are not limiting. Examples

[0079] The present disclosure will be further elaborated based on the following examples. It should be understood that the following examples are illustrative rather than limiting.

[0080] Raw material description

[0081] Name Description BPF Epoxy Bisphenol F epoxy resin, YDF-170 Novolac Epoxy Phenolic varnish, Epikote 170 BPA Epoxy Bisphenol A epoxy resin, YD-128 HDDA Hexanediol diacrylate, 2-functional without branched chains, ALLNEX HDDA TMPTA Trimethylolpropane triacrylate, 3-functional with branched chains LA Lauryl acrylate, monofunctional Flame retardant component Containing polyphosphoric acid hydrochloride source, melamine, titanium dioxide and reinforcing fibers, etc. Rheology aid Mixture containing polyamide wax, clay and fumed silica Curing agent Polyamine curing agent

[0082] Formulation of coating composition

[0083] Components A and B were formulated for each sample according to the composition shown in Table 1 below. Component A includes the epoxy resin components listed in Table 1, (meth)acrylate components such as HDDA, TMPTA or LA, and flame retardant components, while component B includes a curing agent and a rheology aid. At room temperature, the respective components were added one by one in the order of liquid - solid - aid and stirred and dispersed as needed to prepare components A and B. Subsequently, the two components were mixed and stirred thoroughly to prepare the coating composition. The performance of the coating composition was tested according to the different test requirements described above.

[0084] Table 1

[0085]

[0086] Performance test description

[0087] 1. Fire test:

[0088] After components A and B were mixed evenly, they were applied to the H - shaped steel to form a dry film with a thickness of 12 mm. The dimensions of the H - shaped steel were in accordance with the provisions of GB / T11263 - 2017, model HW250X250X9X14. Thermocouples were installed according to the UL263 standard. On each H - shaped steel, 4 layers of thermocouples were installed, with 5 thermocouples in each layer, for a total of 20 thermocouples. The end point of the fire test was judged according to UL263. The fire test was carried out after the coating was cured at room temperature (23°C) for 2 weeks. This test was a four - sided fire test. During the test, the H - shaped steel was placed vertically in the middle of the furnace. The test results were recorded in Table 2.

[0089] Table 2

[0090]

[0091]

[0092] As can be seen from the above table, the comparison between Sample 1 and Samples 2 - 3 shows that the use of bisphenol F epoxy resin and phenolic epoxy resin can result in better fire protection time, and can avoid the sagging of the carbon layer, ensuring the integrity of the carbon layer, thus improving the fire protection time as a whole. In addition, it can also be seen from Sample 4 that when the dosage of HDDA is at a level below 5% by weight, even if a significant amount of TMPTA is added, the carbon layer still sags after a short time.

[0093] 2. Low-temperature anti-cracking performance test:

[0094] T-shaped steel specimens with a length of 400 mm, a width of 120 mm, a height of 120 mm, and a thickness of 3.5 mm were used. The surface of the T-shaped steel was sandblasted and coated with an epoxy zinc-rich primer (Sigma Zinc 109G, available from PPG). Then, the prepared intumescent coating samples 5, 6, 7, 8 and the comparative commercial product (SteelMaster 1200HPE, commercially available from Jotun) were respectively coated on the surface of each T-shaped steel, with a film thickness of 10 mm. The prepared T-shaped steel was cured at room temperature for 24 hours and then at 60°C for 4 hours. Then, the test pieces were subjected to the following 20 cycles of freeze-thaw cycles: frozen in a refrigerator at -20°C for 12 hours; then taken out of the refrigerator and immediately placed in an oven at 40°C for 12 hours.

[0095] After each cycle, the surface condition of each coated sample was visually observed, and the number of cycles before the coating cracked and / or peeled off from the substrate was recorded for each coated sample. The results are shown in Table 3 below. "Pass" means that there is no paint film cracking and no peeling off from the substrate after 20 cycles.

[0096] Table 3

[0097] Sample number Number of cycles 5 20 (passed) 6 1 7 1 8 1

[0098] 3. Adhesion test:

[0099] The adhesion test was carried out according to ASTM D4541. After the coating components A and B were mixed evenly, they were applied to an iron plate of 300x300x5 mm, which had been pre-cleaned with solvent and sandblasted. The dry film of the coating was controlled at about 7 mm. The pull-off adhesion test was carried out after drying at room temperature for 7 days. Three points were tested on each iron plate and the average value was taken and the results were recorded in Table 4.

[0100] Table 4

[0101] Sample number Pull-off adhesion (MPa) 5 9.8 9 3.4

[0102] As can be seen from Table 4, using a monofunctional acrylate (lauryl acrylate (LA)) results in lower mechanical strength compared to HDDA.

Claims

1. An intumescent coating composition, comprising: (a) An epoxy resin having one or more alkylene moieties in the main chain, said alkylene moieties being all selected from divalent alkane groups of the formula wherein Ra and Rb are each independently H, OH or an aromatic group and z is an integer from 1 to 18, such as from 1 to 8, and / or a divalent cycloalkane group; (b) an alkylene di(meth)acrylate, wherein the alkylene moiety has 4, preferably 5 or more carbon atoms; (c) a curing agent; and (d) a compound that provides an expanding gas upon thermal decomposition.

2. The coating composition according to claim 1, wherein the alkylene moiety is a divalent alkane group of the formula wherein Ra and Rb are each independently H or phenyl, preferably H, and z is an integer from 1 to 6, preferably from 1 to 4.

3. The coating composition according to claim 1, wherein the alkylene moiety comprises a methylene group (-CH2-) bridging two aromatic groups such as phenyl groups at both ends.

4. The coating composition according to claim 1, wherein the epoxy resin has the formula X-(G)n, where G represents a glycidyloxy group, X represents an n-valent hydrocarbon group having one or more of said alkylene moieties, optionally one or more ether oxygen atoms and optionally one or more aromatic groups, and n represents an integer greater than or equal to 2, such as 2-6 or preferably 2, 3 or 4.

5. The coating composition according to claim 4, wherein the epoxy resin of the formula X-(G)n comprises polyglycidyl ethers derived from polyols, the polyols including alkane polyols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2,6-hexanetriol, cyclohexanedimethanol, glycerol, trimethylolpropane, bisphenol F, hydrogenated bisphenol F or polyether diols, and also epoxy phenol novolac resin or epoxy cresol novolac resin.

6. The coating composition according to claim 4, wherein the epoxy resin of the formula X-(G)n comprises bisphenol F type epoxy resin, epoxy phenol novolac resin, epoxy cresol novolac resin, 1,6-hexanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, or a combination thereof.

7. The coating composition according to any one of the preceding claims, wherein based on the total weight of the epoxy resin base, at least 90 wt%, at least 95 wt%, at least 98 wt% or at least 99 wt% or all of the epoxy resin is composed of an epoxy resin having one or more of said alkylene moieties in the main chain.

8. The coating composition according to any one of the preceding claims, wherein the alkylene di(meth)acrylate is represented as R(A)2, where R represents an alkylene group having 4, such as 5 or more, such as 6-12 or 6-10 carbon atoms, and A represents a (meth)acrylate group.

9. The coating composition according to any one of the preceding claims, wherein the alkylene di(meth)acrylate comprises pentanediol di(meth)acrylate, hexanediol di(meth)acrylate, heptanediol di(meth)acrylate, octanediol di(meth)acrylate, nonanediol di(meth)acrylate, decanediol di(meth)acrylate, dodecanediol di(meth)acrylate, or a combination thereof, particularly preferably hexanediol di(meth)acrylate.

10. The coating composition according to any one of the preceding claims, wherein the content of component (b) alkylene di(meth)acrylate is in the range of 5-20 wt%, preferably 7-15 wt% based on the total weight of the coating composition.

11. A coating composition according to any one of the preceding claims, wherein the content of the epoxy resin is in the range of 8-40% by weight, preferably 12-30% by weight, based on the total weight of the coating composition.

12. A coating composition according to any one of the preceding claims, wherein the curing agent is selected from aliphatic polyamines, aromatic polyamines, polyamides, polyetheramines, polysiloxaneamines, polysulfideamines or combinations thereof.

13. A method of coating a substrate, comprising applying a coating composition according to any one of claims 1-12 to the substrate.

14. A substrate at least partially coated with a coating deposited from a coating composition according to any one of claims 1-12.

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