Coating composition

Abstract

The present invention provides a coating composition comprising: (A) a resin composition, (B) an acid source component, (C) a carbon source component, and (D) a gas source component; the resin composition comprising (a) a nitrogen and phosphorus containing modified epoxy resin and (b) an aqueous silica sol, wherein component (a) is prepared by a method comprising the steps of: (i) esterifying a cyclotriphosphazene based epoxy resin of Formula I with phosphoric acid to obtain a cyclotriphosphazene based epoxy phosphonate, (ii) esterifying the cyclotriphosphazene based epoxy phosphonate with a C3-6 unsaturated aliphatic acid or an acid anhydride thereof to obtain a cyclotriphosphazene based epoxy phosphonate aliphatic acid ester, and (iii) free radical polymerizing the cyclotriphosphazene based epoxy phosphonate aliphatic acid ester with an ethylenically unsaturated monomer to obtain the nitrogen and phosphorus containing modified epoxy resin, and the ethylenically unsaturated monomer is selected from one or more of a vinyl aromatic compound, an ethylenically unsaturated acid, an ethylenically unsaturated acid alkyl ester, and an ethylenically unsaturated acid alkenyl ester.

Description

TECHNICAL FIELD

[0001] The present application relates to a coating composition. BACKGROUND

[0002] In high temperature environment, the strength of steel material can be rapidly reduced, thus in order to ensure the safety of steel material in high temperature environment (especially when fire occurs), it is necessary to apply appropriate protective measures to the surface of the material. At present, a simple and effective protective measure is to coat a fire-retardant coating on the surface of the steel material. The fire-retardant coating suitable for steel material (for example, building steel structure) mainly includes two categories: non-intumescent fire-retardant coating and intumescent fire-retardant coating. Among them, the water-based ultra-thin intumescent fire-retardant coating has a wide range of applications because it is environmentally friendly, has a small coating thickness, and can meet the requirements of fire-retardant and decorative appearance.

[0003] At present, the common water-based intumescent fire-retardant coating on the market is mostly made of acrylic emulsion, acrylic-vinyl acetate copolymer, vinyl acetate emulsion, etc. as film-forming material, combined with fire retardant to achieve ideal fire-retardant performance. After the film layer is formed, some fire retardants tend to gradually absorb moisture, dissolve and migrate in the film layer, or even precipitate, resulting in poor water resistance of the fire-retardant coating. On the other hand, due to the large amount of addition of fire retardant and / or the inherent performance of film-forming material, the existing water-based intumescent fire-retardant coating has a small and loose thickness of the intumescent carbon layer generated after burning, and the blocking effect of the heat flow generated by burning is insufficient, which is easy to fall off when impacted by the high-temperature hot gas generated by burning, which leads to the failure of fire-retardant performance. In addition, although the film-forming material used in some fire-retardant coatings has good performance, it exists in the form of two-component emulsion before construction, and a curing agent is needed during film formation. Although the paint film obtained by crosslinking and curing is relatively dense, the disadvantage is that the intumescent ratio after burning is relatively low.

[0004] Obviously, the fire-retardant coating suitable for steel substrate in the prior art has many defects. In view of this, there is a need in the art for a water-based intumescent fire-retardant coating which can overcome at least one of the above-mentioned defects and has more balanced performance. SUMMARY

[0005] In view of the above needs, the present application provides a coating composition, which comprises:

[0006] (A) a resin composition, comprising:

[0007] (a) a modified epoxy resin containing nitrogen and phosphorus, which is prepared by a method comprising the following steps:

[0008] (i) esterifying a cyclotriphosphazene-based epoxy resin of Formula I with phosphoric acid to obtain a cyclotriphosphazene-based epoxy phosphate,

[0009]

[0010] wherein

[0011] R1is -O-Ph-CH2- wherein O is attached to P in the cyclotriphosphazene group with a single bond, and R is wherein the ** end is attached to the epoxymethylene moiety with a single bond, and the * end is attached to oxygen with a single bond,

[0012] n = 1 or 2, 3, 4, 5, or 6;

[0013] (ii) esterifying the cyclotriphosphazene group epoxide phosphonate with a C3-6 unsaturated fatty acid or an acid anhydride thereof to obtain a tricyclotriphosphazene group epoxide phosphonate fatty acid ester, and

[0014] (iii) free radical polymerizing the tricyclotriphosphazene group epoxide phosphonate fatty acid ester with an ethylenically unsaturated monomer to obtain the nitrogen and phosphorus containing modified epoxy resin, and the ethylenically unsaturated monomer is selected from one or more of a vinyl aromatic compound, an ethylenically unsaturated acid, an ethylenically unsaturated acid alkyl ester, and an ethylenically unsaturated acid alkenyl ester; and

[0015] (b) an aqueous silica sol;

[0016] (B) an acid source component selected from the group consisting of ammonium polyphosphate, melamine phosphate, or mixtures thereof;

[0017] (C) a carbon source component selected from one or more of pentaerythritol, dipentaerythritol, and tripentaerythritol;

[0018] (D) a gas source component selected from one or more of melamine, ammonium carbonate, and dicyandiamide.

[0019] The coating composition of the present invention is able to overcome at least one of the drawbacks of the prior art, and has a more balanced performance. DETAILED DESCRIPTION

[0020] The aqueous emulsion composition of the present application, its preparation method, and the self-emulsifiable modified epoxy resin embodiment will be described in detail hereinafter. However, there will be cases where unnecessary detailed description is omitted. For example, there will be cases where detailed description of matters well known, repeated description of practically identical structures are omitted. This is to avoid the following description becoming unnecessarily lengthy, and to facilitate understanding by those skilled in the art. Furthermore, the following description is provided in order for those skilled in the art to fully understand the present application, and is not intended to limit the subject matter recited in the claims.

[0021] The ranges disclosed herein are meant to be inclusive of the endpoints and include the end values in the range. Ranges can be combined to form new ranges, e.g., a range of "60-120 and 80-110" is understood to include 60-110 and 80-120. Further, if a minimum range value is listed as 1 and a maximum range value is listed as 3, 4, and 5, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise indicated, a numerical range "a-b" means a range of any combination of the numbers a and b, wherein both a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between 0 and 5 have been listed herein, and "0-5" is merely a shorthand for listing all of those numbers. Also, when a parameter is stated to be an integer > 2, it is equivalent to state that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0022] All embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, unless otherwise specified. All technical features and optional technical features of the present application can be combined with each other to form new technical solutions, unless otherwise specified.

[0023] All steps of the present application can be performed in sequence or randomly, preferably in sequence, unless otherwise specified. For example, the method comprises steps (a) and (b), which means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method can further comprise step (c), which means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0024] Unless otherwise specified, "including" and "comprising" mentioned in the present application means open-ended, which can also be closed. For example, "including" and "comprising" can mean that other components not listed can also be included or contained, or only the listed components can be included or contained.

[0025] If not otherwise specifically defined, the term "or" as used in this application is inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, any of the following conditions satisfy the condition "A or B": A is true (or present) and B is false (or not present); A is false (or not present) and B is true (or present); or both A and B are true (or present).

[0026] As used herein, unless specifically explained otherwise, the terms have their common and ordinary meaning in the art. As used herein, unless otherwise specifically indicated, all materials are commercially available.

[0027] The present application provides a coating composition comprising:

[0028] (A) a resin composition comprising:

[0029] (a) a nitrogen and phosphorus containing modified epoxy resin prepared from a process comprising the steps of:

[0030] (i) esterifying a cyclotriphosphazene based epoxy resin of Formula I with phosphoric acid to obtain a cyclotriphosphazene based epoxy phosphonate,

[0031]

[0032] wherein,

[0033] R1is -O-Ph-CH2- wherein O is connected to P in the cyclotriphosphazene group with a single bond,

[0034] R is wherein the ** end is connected to the epoxy methylene moiety with a single bond and the * end is connected to oxygen with a single bond,

[0035] n = 1, 2, 3, 4, 5, or 6;

[0036] (ii) esterifying the cyclotriphosphazene based epoxy phosphonate with a C3-6unsaturated fatty acid or an acid anhydride thereof to obtain a cyclotriphosphazene based epoxy phosphonate fatty acid ester, and

[0037] (iii) free radical polymerizing the cyclotriphosphazene based epoxy phosphonate fatty acid ester with an ethylenically unsaturated monomer to obtain the nitrogen and phosphorus containing modified epoxy resin, and the ethylenically unsaturated monomer is selected from one or more of a vinyl aromatic compound, an ethylenically unsaturated acid, an ethylenically unsaturated acid alkyl ester, and an ethylenically unsaturated acid alkenyl ester; and

[0038] (b) an aqueous silica sol;

[0039] (B) an acid source component selected from the group consisting of ammonium polyphosphate, melamine phosphate, or mixtures thereof;

[0040] (C) a carbon source component selected from one or more of pentaerythritol (PER), di-pentaerythritol (DPER), and tri-pentaerythritol (TPER);

[0041] (D) a gas source component selected from one or more of melamine, ammonium carbonate, and dicyandiamide.

[0042] Without being bound by any theory, the coating composition of the present application can form a film layer with high thermal stability, good fire-retardant property, good water resistance, and good adhesion to the substrate after coating; and after film formation, the coating composition of the present application can effectively reduce or avoid the moisture absorption, migration, and precipitation of the fire-retardant intumescent system comprising components B, C, and D, thereby improving the water resistance of the fireproof film layer. At the same time, the film layer formed by the coating composition of the present application can form a carbon layer with high expansion height and relatively dense uniformity on the surface of the substrate during combustion, thereby facilitating the reduction of the adverse effects of high-temperature burning on the substrate and improving the fire resistance. At the same time, the coating composition of the present application contains phosphorus, nitrogen, and silicon elements, which work together to improve the fire-retardant effect: the phosphorus-containing condensed phase is generated during combustion to provide a solid-phase fire-retardant layer on the surface of the substrate, the non-combustible gases (such as ammonia, nitrogen, and carbon dioxide) released provide a gas-phase fire-retardant near the surface, and the presence of silicon elements also improves the overall strength and density of the carbon layer, reducing the risk of carbon layer detachment. Compared with existing intumescent fire-retardant coatings, the coating composition of the present application can achieve better fire-retardant effect (for example, significantly improved fire resistance time) under the same coating thickness.

[0043] At the same time, the resin composition A used in the present application is a water-based single-component emulsion that can dry and form a film after coating without the addition of film-forming aids (such as curing agents) for assistance. The coating composition of the present application is convenient and simple to use and has a long window period because it does not need to add curing agents and stir at the construction site. Moreover, the coating composition of the present application is also conducive to long-term storage because it does not contain curing agents.

[0044] Herein, "intumescent fire-retardant coating" means that the coating layer formed by the coating will intumesce under the action of fire or high temperature to form a carbon layer several times thicker than the original coating layer, thereby more effectively blocking the continuous action of external heat sources or combustion flames on the substrate. According to GB 14907-2002, thin-type fire-retardant coating is fire-retardant coating with a coating thickness of 3-7 mm, and ultra-thin-type fire-retardant coating is fire-retardant coating with a coating thickness of less than 3 mm. Herein, the term "thin-type coating" and similar terms include thin-type fire-retardant coating and ultra-thin-type fire-retardant coating.

[0045] As used herein, "one-component emulsion" means an emulsion that does not require additional addition of a film-forming aid (e.g., a curing agent). Such an emulsion can be used directly or after dilution with water, and it can form a film during the process of evaporation and drying of moisture without the film-forming aid. Accordingly, "two-component emulsion" means an emulsion that requires assistance of a film-forming aid to form a film. As used herein, any expression relating to "one-component" or "two-component" is understood in the above similar meaning.

[0046] As used herein, "film formation" means that an emulsion or a coating forms a film layer on a substrate surface through a physical process (e.g., evaporation of moisture).

[0047] In some embodiments, the resin composition (A) is present in an amount of 20-40%, preferably 25-35%, more preferably 30-35%, based on the total weight of the coating composition.

[0048] The composition of the present application, when film-formed, the components in component (A) remain in a physically mixed state without chemical reaction.

[0049] In some embodiments, the acid source component is present in an amount of 10-40%, preferably 20-30%, more preferably 20-25%, still more preferably 22-24%, based on the total weight of the coating composition. In some embodiments, the acid source component is ammonium polyphosphate; preferably, the ammonium polyphosphate satisfies one or more of the following conditions:

[0050] (1) the degree of polymerization n > 1000, which makes the water solubility of the ammonium polyphosphate moderate and suitable for use in fire-retardant coatings;

[0051] (2) the phosphorus content is higher than 30%, preferably 30-32%, more preferably 31-32%;

[0052] (3) the nitrogen content is 14-15%; in some embodiments, the acid value of the ammonium polyphosphate is < 1 mg KOH / g, and / or the pH is 5.5-7.5, and / or the water solubility (25°C) is < 0.5 g / 100 g water.

[0053] In some embodiments, the average particle size of the acid source component is not greater than 15 μm, which is advantageous for the film layer formed by the coating composition to be dense, thereby improving the fire resistance.

[0054] In some embodiments, the carbon source component is present in an amount of 5-20%, preferably 10-15%, more preferably 10-12%, based on the total weight of the coating composition. In some embodiments, the carbon source component is pentaerythritol. In some embodiments, the pentaerythritol has a hydroxyl content ≥ 47%, and / or a water absorption ≤ 1.0%, and / or an ash content ≤ 0.1%.

[0055] In some embodiments, the average particle size of the carbon source component is not greater than 15 pm, which is advantageous for densifying the film layer and improving fire resistance.

[0056] In some embodiments, the gas source component is present in an amount of 5-20%, preferably 10-15%, more preferably 10-12%, based on the total weight of the coating composition. In some embodiments, the gas source component is melamine. In some embodiments, the melamine purity is > 99.5%.

[0057] In some embodiments, the average particle size of the carbon source component is not greater than 15 pm, which is advantageous for densifying the film layer and improving fire resistance.

[0058] Upon a fire, the acid source component, the carbon source component, and the gas source component form a fire retardant system, which collectively act to provide a fire retardant effect while expanding the coating layer to form a carbon layer on the surface of the substrate that blocks the flame. In this process, the acid source decomposes upon heating to generate an acid, which esterifies with the carbon source; at the same time, the gas source decomposes upon heating to release an incombustible gas, which causes the resin in a molten state and the esterification product in a viscous state to expand, generating a fireproof expanded layer (i.e., carbon layer) with a significantly increased thickness.

[0059] In some embodiments, the composition further comprises other fire retardant additives, preferably selected from titanium dioxide, kaolin, or a combination thereof.

[0060] Titanium dioxide can form an inorganic substance layer after burning, which better prevents heat from being transferred to the substrate, improving the fireproof performance. In some embodiments, the titanium dioxide can be R2-rutile type, and / or wherein Ti02is > 95%, and / or volatile matter content is < 0.5%, and / or average particle size is < 10 pm. The coating composition of the present application can comprise titanium dioxide in an amount of 8-12%, based on the total weight of the coating composition.

[0061] Kaolin helps to vitrify the carbon layer upon burning, further improving the thermal stability of the carbon layer. In some embodiments, the average particle size of the kaolin is < 10 pm, and / or wherein the residue on sieve is < 0.01%, and / or moisture is < 0.5%, and / or oil absorption is 35 ± 5 g / 100 g. The coating composition of the present application can comprise kaolin in an amount of 1-5%, based on the total weight of the coating composition.

[0062] In some embodiments, the coating composition further comprises a defoaming agent. In some embodiments, the defoaming agent is selected from BYK-093 of BYK-Chemie Group, WINCREST® 1000 of Wincrete Group, AIREX 902W of Airex Group, and ZHENXIN 901 of Zhenxin Group. Airex 902W and Zhenxin Group's One or more of VXW 6393. These defoamers have similar effects in this invention and have no significant impact on fire resistance. In some embodiments, VXW 6393 is preferred as the defoamer. The defoamer may be present in the coating composition at an amount of 0.5-1%, based on the total weight of the coating composition.

[0063] In some embodiments, the coating composition further includes a dispersant. In some embodiments, the dispersant is selected from Zhanxin Group. VVXW 6208, BYK-190 from BYK Chemicals, and Evonik One or more of Dispers 755W are used. These dispersants have similar effects in this invention and have no significant impact on fire retardancy. In some embodiments, BYK190 is preferred as the dispersant. The dispersant may be present in the coating composition at an amount of 0.5-1%, based on the total weight of the coating composition.

[0064] In some embodiments, the coating composition further comprises a co-solvent. The co-solvent is used to adjust the drying (film-forming) rate of the coating, improve the film formation of the resin composition, and prevent film cracking due to excessively rapid drying. The co-solvent may be present in the coating composition at an amount of 1-2%, based on the total weight of the coating composition. In some embodiments, the co-solvent may be decyl alcohol (C... 12 H 24 O3), as shown in the following formula:

[0065]

[0066] In some embodiments, the coating composition also includes other components, such as pigments.

[0067] In some embodiments, the coating composition of the present invention may further comprise water, preferably deionized water. Water may be present in the coating composition in an amount of 2-10%, based on the total weight of the coating composition.

[0068] In some embodiments, in step (i) of preparing component (A), the molar ratio of the cyclotriphosphazene epoxy resin (based on epoxy groups) to the molar ratio of phosphoric acid is 7 to 1:1, and not 1:1. This is beneficial for the emulsion composition of the present invention to possess improved adhesion, water and salt spray resistance, and improved fire resistance after film formation. In some embodiments, this molar ratio is preferably 5 to 1:1, and not 1:1; more preferably 3.5 to 1.1:1. In some embodiments, this molar ratio can be 6.78:1, 4.55:1, 3.48:1, 2.27:1, 1.51:1, 1.2:1, or the ratio can be within any range of both of the above. Preferably, the molar ratio is 2.27:1.

[0069] In some embodiments, the phosphoric acid in step (i) can be in the form of a concentrated solution of phosphoric acid. In some embodiments, the phosphoric acid is preferably an 85 wt.% solution of phosphoric acid in water. The reaction system contains less water, which is beneficial for the esterification reaction to proceed. In some embodiments, the phosphoric acid is added to the reaction system in the form of a mixture of phosphoric acid (e.g., an 85% solution of phosphoric acid in water) and acetone, preferably in a mass ratio of 1 : 1 to 2 of the 85% solution of phosphoric acid in water to acetone. In this context, all percentages (%) are weight percentages (i.e., wt.% or wt.%) unless otherwise specified.

[0070] In some embodiments, n in Formula I is 1 or 2.

[0071] In some embodiments, the phosphoric acid (which can be in any of the forms described above) is added to the cyclotriphosphazene-based epoxy resin of Formula I at a controlled rate with stirring, preferably at a rate of 1 drop per second. After the addition is complete, stirring is continued until the reaction reaches the end point. After the reaction is complete, the solvent is removed to obtain the epoxy phosphonate.

[0072] The end point of the reaction can be determined by the acid value: after the addition of the phosphoric acid is complete, the acid value is determined from the reaction mixture every 0.5 hours (h) until it is observed that the acid value no longer decreases, i.e., the reaction reaches the end point. The determination of the acid value is known to those skilled in the art.

[0073] In some embodiments, the esterification reaction of step (i) can be carried out in a solvent selected from the group consisting of acetone, butanone, toluene, xylene, butyl acetate, methanol, and dichloromethane, and a mixture of any two or more thereof; preferably a mixture of acetone and butanone.

[0074] In some embodiments, the esterification reaction of step (i) is carried out at a temperature of 50-60 °C, preferably 55 °C.

[0075] In some embodiments, the esterification reaction of step (i) can be carried out in the presence of a catalyst. Preferably, the catalyst can be phosphotungstic acid.

[0076] In some embodiments, the epoxy phosphonate obtained from step (i) above is subjected to an esterification reaction with a C3-6 unsaturated aliphatic acid (i.e., step (ii)) to introduce an olefinic bond into the epoxy resin for subsequent modification (e.g., step (iii)).

[0077] In some embodiments, in step (ii), the C3-6 unsaturated aliphatic acid is selected from one or more of acrylic acid, methacrylic acid, and maleic acid, preferably acrylic acid and / or methacrylic acid.

[0078] In some embodiments, the esterification reaction of step (ii) is carried out at a temperature of 120-150 °C.

[0079] In some embodiments, the esterification reaction of step (ii) is carried out in the presence of a catalyst. The catalyst is routinely selected by one skilled in the art; for example, the catalyst is at least one of calcium oxide, lead oxide, lithium hydroxide, dibutyl tin, stannous octoate, lithium naphthenate, triphenyl phosphine, monobutyl tin oxide, and calcium naphthenate.

[0080] In some embodiments, an organic solvent is added to the system at the end of the esterification reaction of step (ii) to reduce the viscosity of the system. Preferably, the organic solvent is one or more alcohol ether solvents, preferably at least one selected from the group consisting of propylene glycol butyl ether, n-butanol, ethylene glycol butyl ether, glycerol methyl ether, propylene glycol methyl ether, and isobutyl alcohol, more preferably selected from the group consisting of propylene glycol methyl ether, ethylene glycol butyl ether, n-butanol, or a mixture of two or more of the foregoing. In some embodiments, the addition of the organic solvent results in a solid content of the resulting tricyclophosphazene-based epoxy phosphonolipid fatty acid ester solution of 55 wt% to 90 wt%, preferably 60 wt% to 80 wt%, based on the total weight of the solution.

[0081] During the esterification reaction of step (ii), the acid value of the reaction system is determined, and when an acid value < 10 mgKOH / g is observed, the reaction reaches the end point, i.e., the intermediate product tricyclophosphazene-based epoxy phosphonolipid fatty acid ester is obtained.

[0082] As described above, the ethylenically unsaturated monomer can be selected from one or more of a vinyl aromatic compound, an ethylenically unsaturated acid, an ethylenically unsaturated alkyl ester of an acid, and an ethylenically unsaturated alkenyl ester of an acid. In some embodiments, the ethylenically unsaturated monomer is preferably selected from one or more of a C1-6linear or branched alkyl vinyl carboxylate, a C6-10aryl vinyl, a C1-12linear or branched alkyl (meth)acrylate, and (meth)acrylic acid. In some embodiments, more preferably, the ethylenically unsaturated monomer is selected from one or more of a C1-4linear or branched alkyl vinyl carboxylate, a C6-10aryl vinyl, a C1-10linear or branched alkyl acrylate, a C1-6linear or branched alkyl methacrylate, and (meth)acrylic acid. Even more preferably, the ethylenically unsaturated monomer is selected from one or more of vinyl acetate, isooctyl acrylate, vinyl versatate, acrylic acid, styrene, butyl acrylate, methacrylic acid, methyl methacrylate, ethyl acrylate, vinyl versatate, acrylic acid.

[0083] Herein, "(meth)acrylic acid" means both acrylic acid and methacrylic acid.

[0084] Step (iii) is carried out in the presence of an initiator. The initiator is routinely selected by one skilled in the art. For example, the initiator can be benzoyl peroxide (BPO).

[0085] In some embodiments, the reaction temperature of step (iii) is 85-130°C.

[0086] In some embodiments, in step (iii), the ethylenically unsaturated monomer is added in a dropwise manner. In some embodiments, the dropwise addition is performed for 2-4 hours.

[0087] In some embodiments, in step (iii), after the addition of the ethylenically unsaturated monomer is completed (e.g., dropwise addition is completed), the reaction mixture is incubated at 100-140°C, so that the reaction is allowed to proceed to completion. In some embodiments, the incubation is performed for 3-6 hours.

[0088] In some embodiments, after the incubation is completed, the reaction mixture is cooled to 40-70°C, and then a neutralizing agent is added. The amount of the neutralizing agent is determined based on the amount of residual carboxyl groups of the methacrylic acid or acrylic acid in the system after the reaction. Generally, the amount of the neutralizing agent is 60-150%, preferably 90%-120%, based on the molar amount of the residual carboxyl groups. In some embodiments, the neutralizing agent can be selected from one or more of triethylamine (TEA), aqueous ammonia, N,N-dimethylglycolamine (DMAC), 2-amino-2-methyl-1-propanol (AMBP), and N,N-dimethylethanolamine (DMEA). In some embodiments, the neutralization reaction is performed for 0.5-3 hours. The neutralization allows the carboxylic acid in the reaction system to form a salt, so that the system has better hydrophilicity and is more easily dispersed into an aqueous solution when water is added. After the neutralization, the pH of the system is approximately neutral to weakly basic, preferably, the pH of the system is 6-10, more preferably 7-9, and even more preferably 8-9.

[0089] After the nitrogen- and phosphorus-containing modified epoxy resin is neutralized, the silica sol diluted with water is added and dispersed to obtain the water-based emulsion composition of the present application.

[0090] In some embodiments, the resin composition comprises 40-50%, preferably 43%-49%, of component (a), based on the total weight of the resin composition. In some embodiments, the resin composition of the present application consists of component (a) and component (b).

[0091] Herein, "water-based silica sol" refers to a colloidal solution in which colloidal silica particles are uniformly dispersed in water.

[0092] In some embodiments, the aqueous silica sol has a solid content of 6.5% to 12.5%, preferably 6.5% to 12%, more preferably 7% to 12%, and even more preferably 7% to 11.5%. In the present application, the aqueous silica sol with a low solid content is added to the modified epoxy resin as a dispersant, which is beneficial to the uniform dispersion of silica in the final formed composition (aqueous dispersion) system and in the film layer after film formation. Moreover, the viscosity of the composition is not too large to affect its stability; the composition has good film-forming properties, and the film layer does not crack; and the carbon layer produced after burning of the film layer is more compact.

[0093] As described above, the aqueous silica sol comprises silica. In some embodiments, the resin composition comprises 3% to 6%, preferably 3.5% to 6%, of silica based on the total weight of the resin composition.

[0094] The composition of the present application does not comprise an emulsification aid (e.g., an emulsifier) and / or a film-forming aid (e.g., a curing agent). In the composition of the present application, the resin composition (A) is an aqueous dispersion and can form a single-component emulsion with components (B)-(D) without the need for a film-forming aid (e.g., a curing agent, etc.) to form a film.

[0095] In some embodiments, the coating composition of the present application can further comprise other resins or resin compositions.

[0096] In some embodiments, the coating composition of the present application can be obtained by a method comprising the following steps:

[0097] 1. providing a resin composition (A), preferably, the resin composition (A) can be prepared by the following steps:

[0098] (1) preparing a modified epoxy resin containing nitrogen and phosphorus, comprising:

[0099] (i) esterifying a cyclotriphosphazene-based epoxy resin of Formula I with phosphoric acid to obtain a cyclotriphosphazene-based epoxy phosphonate,

[0100]

[0101] wherein,

[0102] R1is -O-Ph-CH2-, wherein O is connected to P in the cyclotriphosphazene group by a single bond,

[0103] R is wherein the ** end is connected to the epoxy methylene moiety by a single bond, and the * end is connected to oxygen by a single bond,

[0104] n = 1, 2, 3, 4, 5, or 6;

[0105] (ii) esterifying the cyclotriphosphazene-based epoxy phosphate with a C3-6 unsaturated fatty acid or an acid anhydride thereof to obtain a cyclotriphosphazene-based epoxy phosphate fatty acid ester, and

[0106] (iii) subjecting the cyclotriphosphazene-based epoxy phosphate fatty acid ester to a radical polymerization reaction with an ethylenically unsaturated monomer to obtain the nitrogen- and phosphorus-containing modified epoxy resin, and the ethylenically unsaturated monomer is selected from one or more of a vinyl aromatic compound, an ethylenically unsaturated acid, an ethylenically unsaturated acid alkyl ester, and an ethylenically unsaturated acid alkenyl ester;

[0107] (2) under stirring, adding an aqueous silica sol into the nitrogen- and phosphorus-containing modified epoxy resin, and then continuing to keep stirring until a uniformly dispersed emulsion is obtained;

[0108] 2. The resin composition (A) and deionized water are stirred and mixed, and then under stirring conditions, the acid source component (B), the carbon source component (C), the gas source component (D), and other components including a defoaming agent, a dispersing agent, and kaolin are sequentially added, stirred and dispersed, and then preferably under a reduced stirring rate, a cosolvent is added and dispersed for 10 min. Finally, the material is filtered out using a 120-mesh filter screen, and the fireproof coating fineness is ≤ 30 μm.

[0109] The various descriptions above apply to the corresponding content / features below; vice versa.

[0110] In the above method for preparing the resin composition, the preparation of the cyclotriphosphazene-based epoxy resin (PN-EP) of Formula I in step (1) is known to those skilled in the art, for example, it can be prepared according to the method described in Liu R, Wang X. Synthesis, characterization, thermal properties and flame retardancy of a novel nonflammable phosphazene-based epoxy resin [J]. Polymer Degradation & Stability, 2009, 94(4): 617-624:

[0111] The first step is to mix 274 g of sodium (70 wt% in oil dilution) and 976 g of 4-hydroxybenzaldehyde solution (500 mL THF) in a reactor to prepare a suspension of 4-aldehyde phenoxy sodium in dry THF under mechanical stirring, reflux condensation and nitrogen inlet. 348 g of hexachlorocyclotriphosphazene (N3P3Cl6) is dissolved in 400 mL of THF and dropped into the flask for 60 minutes (min) at 65°C for 48 h. After recrystallization with ethyl acetate, light brown hexakis(4-aldehyde-phenoxy)-cyclotriphosphazene (PN-CHO) powder can be obtained with a yield of 70.5 wt%;

[0112] The second step is to add NaBH4(56 g) to the reactor containing 200 g of PN-CHO solution in a 500 mL THF / methanol mixture. Stirring at room temperature for 14 h, recrystallization with 90 vol% ethanol gives hexakis(4-hydroxyphenoxy)-cyclotriphosphazene (PN-OH) as a white solid with a yield of 79.6 wt%;

[0113] The third step is to add epoxy resin E44 (1000 g) to the reactor, stir at 120°C for 2 h under a nitrogen atmosphere, then add 318 g of PN-OH in an equal ratio of 1:14 with DGEBA and an appropriate amount of triphenylphosphine (0.3 wt%) as a catalyst. The reaction mixture is kept at 175°C for 5 h.

[0114] The PN-EP used in the embodiments of the present application is prepared as described above.

[0115] In the present application, the epoxy resin used to prepare the PN-EP can be any bisphenol epoxy resin known in the art in addition to the epoxy resin E44 described above. In some embodiments, the PN-EP of the present application is prepared from a low molecular weight bisphenol A epoxy resin, preferably epoxy resin E44 or E51, more preferably E44. When the epoxy resin used to prepare the cyclotriphosphazene-based epoxy resin of formula I is epoxy resin E44 or E51, then n < 2. In other words, the present application preferably has n = 1 or 2 in formula I.

[0116] The above preparation process can be described exemplarily by the following synthetic route:

[0117]

[0118] In some embodiments, in the above step (2), the modified epoxy resin obtained in the above step (1) is kept at a temperature of 30-70°C, and the aqueous silica sol is slowly added dropwise under high-speed stirring, and the viscosity of the system is observed. As the addition proceeds, the viscosity of the system first increases and then decreases, and after the phase inversion is completed, the remaining diluent can be quickly added, and the dispersion is continuously maintained under high-speed stirring, and after uniform dispersion, the emulsion mixture of the present application is obtained.

[0119] In the present application, the judgment of whether the phase inversion is completed or not is made as follows: in the initial stage, after the addition of the aqueous silica sol, the viscosity increases and the system becomes turbid; with the further addition of the aqueous silica sol, the viscosity continues to increase and the system gradually becomes semi-transparent or more uniform in appearance. At this time, it can be considered that the phase inversion is basically completed, but the viscosity of the system is still large. After the phase inversion is completed, the further addition of the remaining aqueous silica sol can adjust the viscosity of the system to the desired state.

[0120] In some embodiments, the stirring speed in step (2) can be higher than 1000 revolutions per minute (r / min), preferably 2000-3000 r / min. During the stirring and dispersion process, the state of the emulsion should be observed; generally, when uniform dispersion is observed, the dispersion can be stopped. In some embodiments, the dispersion time is 1-2 hours. This is beneficial to obtain a uniformly dispersed, fine and stable emulsion.

[0121] In some embodiments, the solid content of the emulsion composition of the present application is 20-40%. This is beneficial to the stable and uniform emulsion system and has appropriate viscosity.

[0122] The coating composition of the present application is suitable for fireproof coating of steel structures in various types of petroleum equipment, chemical equipment, power equipment, and buildings, for example.

[0123] Examples

[0124] The present application will be further illustrated by the following examples:

[0125] [Methods]

[0126] 1. Preparation method of the resin composition:

[0127] (1) Aqueous silica sol:

[0128] Take 80 g of commercially available aqueous silica sol (solid content 30% by weight) and add 240 g of deionized water to disperse uniformly by ultrasonic, to obtain the aqueous silica sol used herein.

[0129] (2) Preparation of modified epoxy resin containing nitrogen and phosphorus:

[0130] Take 330g PN-EP into a four-necked flask, then add 50g butanone and 50g acetone mixed solution to dissolve PN-EP, the temperature is 55℃, then add 2g phosphotungstic acid, then add 30g 85% phosphoric acid and 45g acetone mixed solution drop by drop, the molar ratio of PN-EP to phosphoric acid is 2.27:1, then measure the acid value every half an hour until the acid value does not change, then the reaction is completed. Then remove the acetone and butanone in the system by vacuum distillation to obtain cyclotriphosphazene-based epoxy phosphoric acid ester. Then the temperature is raised to 125℃, 20g acrylic acid and 1.5g monobutyl tin oxide are added, the reaction temperature is kept at 125℃ until the acid value is less than 10mg KOH / g, the esterification reaction is completed, then 200g ethylene glycol butyl ether is added to obtain cyclotriphosphazene-based epoxy phosphoric acid acrylate.

[0131] Take another 150g of the above cyclotriphosphazene-based epoxy phosphoric acid acrylate and add it to a four-necked flask containing a stirrer, condenser, thermometer, and dropping funnel, and the temperature is 95℃. Mix 60g of vinyl acetate, 20g of styrene, 18g of butyl acrylate, 8g of vinyl versatate, 12g of methyl methacrylate, and 5g of BPO uniformly, and then add the mixture to the cyclotriphosphazene-based epoxy phosphoric acid acrylate at a constant speed. Control the speed to complete the drop in 3h, then raise the temperature to 115℃ and keep it for 3h. After the incubation is complete, lower the temperature to 50℃, add 15g of triethylamine for neutralization, and then keep the temperature at 50℃ and stir at high speed for 1h.

[0132] (3) Preparation of resin composition:

[0133] Cool the above neutralized material to 35℃, then add aqueous silica sol dropwise under high-speed dispersion, and complete the drop in 30min. Then continue to disperse for 50min, and then discharge.

[0134] 2. Preparation method of coating composition:

[0135] According to the amounts shown in Table 1 below, add the resin composition and deionized water to a batching tank, start stirring and set the speed to 500r / min. Under stirring conditions, add defoaming agent, dispersant, ammonium polyphosphate, pentaerythritol, melamine, and kaolin in the order of the proportions, and after the addition is complete, disperse at 1500r / min for 0.5h, reduce the speed to 800r / min, add alcohol ester twelve, and disperse for 10min to make it uniformly dispersed. Finally, filter the discharge through a 120 mesh filter screen, and the fireproof coating fineness is ≤30μm.

[0136] 3. Test method:

[0137] (1) Preparation method of water resistance, fire resistance, and adhesion test board:

[0138] According to the GB14907-2018 steel structure fire retardant coating standard, a certain amount of self-made fire retardant coating was taken and brushed on Q235 steel plate, the thickness of each brushing was 0.3-0.5mm, the next brushing was carried out after natural drying for 24h, the final brushing thickness was 1.5mm as required by the standard, and the test was carried out after standing for 10 days under the condition of room temperature 25℃ and humidity 50%.

[0139] (2) Water resistance test:

[0140] The test plate was completely immersed in a container containing tap water, and the time when at least one of the phenomena of delamination, foaming and peeling of the paint film occurred was recorded;

[0141] (3) Adhesion test:

[0142] According to GB14907-2018;

[0143] (4) Carbon layer expansion ratio and carbon layer density test:

[0144] The test equipment used was FQD15-1 type explosion-proof gasoline torch, which was burned with an outer flame (temperature up to 1000℃) for 30min. The height of the coating before burning and the height of the carbon layer after burning were recorded, and the ratio of the height of the carbon layer after expansion to the height of the coating before burning was calculated, which was the expansion ratio. The carbon layer density was determined by visually observing the uniformity of the expanded carbon layer and measuring the size of the carbon layer pores.

[0145] The above test results are recorded in Table 2.

[0146] Examples 1-3 and Comparative Examples 1-3

[0147] Examples 1-3 used the resin composition described above and were prepared according to the method described above. The resin composition of Comparative Example 1 was Clariant DM230 acrylic copolymer resin, the resin composition in Comparative Example 2 was Huntsman PZ 3961-1 epoxy resin, and the resin composition in Comparative Example 3 was Tianhe TH-8386 epoxy modified acrylic resin, and 0.1% of the catalyst HLD-061 was added when preparing the coating composition. The addition amount of the common components in the above examples and comparative examples is shown in Table 1 below, wherein the percentage content is based on the total weight of the final coating composition.

[0148] Table 1

[0149]

[0150]

[0151] The coating compositions prepared in the above examples and comparative examples were respectively prepared into test panels and tested for performance according to the test methods above. The coating composition of Comparative Example 2 was required to be combined with Henschel 3986 610% aliphatic amine curing agent when preparing the coating test panels. The test results are summarized in Table 2 below.

[0152] Table 2

[0153]

[0154] As can be seen from the above table, compared with the existing intumescent fire-retardant coating, the coating composition of the present application can achieve better fire-retardant effect with the same coating thickness and the same (or even less) amount of flame retardant, the carbon layer has higher expansion ratio, is more uniform and dense, and the fire resistance time is significantly improved.

[0155] Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the application being indicated by the following claims.

[0156] It is to be understood that the application is not limited to the above-described embodiments and can be varied in many ways. The scope of the application is limited only by the following claims.

Claims

1. A coating composition comprising: (A) a resin composition comprising: (a) a nitrogen and phosphorus containing modified epoxy resin prepared from a process comprising the steps of: (i) esterifying a cyclotriphosphazene based epoxy resin of Formula I with phosphoric acid to obtain a cyclotriphosphazene based epoxy phosphonate, I wherein, R1 is -0-Ph-CH2- wherein O is attached to P in the cyclotriphosphazene group with a single bond, R is wherein the **end is connected to the epoxymethylene moiety with a single bond and the *end is connected to oxygen with a single bond, n = 1 or 2, 3, 4, 5 or 6; (ii) esterifying the cyclotriphosphazene based epoxy phosphonate with a C3-6 unsaturated fatty acid or an anhydride thereof to obtain a tricyclophosphazene based epoxy phosphonate fatty acid ester, and (iii) free radical polymerizing the tricyclophosphazene based epoxy phosphonate fatty acid ester with an ethylenically unsaturated monomer selected from one or more of a vinyl aromatic compound, an ethylenically unsaturated acid, an ethylenically unsaturated alkyl ester of an acid and an ethylenically unsaturated alkenyl ester of an acid to obtain the nitrogen and phosphorus containing modified epoxy resin; and (b) an aqueous silica sol; (B) an acid source component selected from ammonium polyphosphate, melamine phosphate or mixtures thereof; (C) a carbon source component selected from one or more of pentaerythritol, di-pentaerythritol and tri-pentaerythritol; (D) a gas source component selected from one or more of melamine, ammonium carbonate and dicyandiamide.

2. The coating composition of claim 1 wherein the resin composition (A) is present in an amount of 20-40% based on the total weight of the coating composition.

3. The coating composition of claim 2 wherein the resin composition (A) is present in an amount of 25-35% based on the total weight of the coating composition.

4. The coating composition of claim 3 wherein the resin composition (A) is present in an amount of 30-35% based on the total weight of the coating composition.

5. The coating composition of claim 1 or 2 wherein the acid source component is present in an amount of 10-40% based on the total weight of the coating composition.

6. The coating composition of claim 5 wherein the acid source component is present in an amount of 20-30% based on the total weight of the coating composition.

7. The coating composition of claim 6 wherein the acid source component is present in an amount of 20-25% based on the total weight of the coating composition.

8. The coating composition of claim 7 wherein the acid source component is present in an amount of 22-24% based on the total weight of the coating composition.

9. The coating composition of claim 5 wherein the acid source component is ammonium polyphosphate.

10. The coating composition of claim 9 wherein the ammonium polyphosphate meets one or more of the following conditions: (1) degree of polymerization n > 1000; (2) phosphorus content higher than 30%; (3) nitrogen content 14-15%.

11. The coating composition of claim 10 wherein the phosphorus content is 31-32%.

12. The coating composition of claim 1 or 2, wherein the carbon source component is present in an amount of 5-20% based on the total weight of the coating composition.

13. The coating composition of claim 12, wherein the carbon source component is present in an amount of 10-15% based on the total weight of the coating composition.

14. The coating composition of claim 13, wherein the carbon source component is present in an amount of 10-12% based on the total weight of the coating composition.

15. The coating composition of claim 12, wherein the carbon source component is pentaerythritol.

16. The coating composition of claim 1 or 2, wherein the gas source component is present in an amount of 5-20% based on the total weight of the coating composition.

17. The coating composition of claim 16, wherein the gas source component is present in an amount of 10-15% based on the total weight of the coating composition.

18. The coating composition of claim 17, wherein the gas source component is present in an amount of 10-12% based on the total weight of the coating composition.

19. The coating composition of claim 16, wherein the gas source component is melamine.

20. The coating composition of claim 1 or 2, further comprising an additional flame retardant additive.

21. The coating composition of claim 20, wherein the additional flame retardant additive is selected from titanium dioxide, kaolin, or a combination thereof.

22. The coating composition of claim 1 or 2, further comprising one or more of a defoamer, a dispersant, a co-solvent, and a pigment.

23. The coating composition of claim 1 or 2, wherein the ratio of the molar amount of the cyclotriphosphazene-based epoxy resin to the molar amount of the phosphoric acid in step (i) is 7-1 : 1 and is not 1 :

1.

24. The coating composition of claim 23, wherein the ratio of the molar amount of the cyclotriphosphazene-based epoxy resin to the molar amount of the phosphoric acid in step (i) is 5-1 : 1 and is not 1 :

1.

25. The coating composition of claim 1, wherein the ratio of the molar amount of the cyclotriphosphazene-based epoxy resin to the molar amount of the phosphoric acid in step (i) is 3.5-1.1 :

1.

26. The coating composition of claim 1 or 2, wherein the aqueous silica sol has a solids content of 6.5% to 12.5% based on the total weight of the aqueous silica sol.

27. The coating composition of claim 26, wherein the aqueous silica sol has a solids content of 6.5% to 12% based on the total weight of the aqueous silica sol.

28. The coating composition of claim 27, wherein the aqueous silica sol has a solids content of 7% to 12% based on the total weight of the aqueous silica sol.

29. The coating composition of claim 28, wherein the aqueous silica sol has a solids content of 7% to 11.5% based on the total weight of the aqueous silica sol.

30. The coating composition according to claim 1 or 2, wherein the resin composition comprises 3 to 6% of silica, based on the total weight of the resin composition.

31. The coating composition according to claim 30, wherein the resin composition comprises 3.5 to 6% of silica, based on the total weight of the resin composition.

32. The coating composition according to claim 1 or 2, wherein the resin composition comprises 40 to 50% of component (a), based on the total weight of the resin composition.

33. The coating composition according to claim 1 or 2, which does not comprise an emulsification aid and / or a film-forming aid.

34. The coating composition according to claim 33, which does not comprise an emulsifier and / or a curing agent.

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