Aqueous emulsion composition and process for its preparation

Abstract

An aqueous emulsion composition comprising: (A) a nitrogen and phosphorus containing modified epoxy resin and (B) an aqueous silica sol, wherein component (A) is prepared by 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 phosphate ester, (ii) esterifying the cyclotriphosphazene based epoxy phosphate ester with a C3-6 unsaturated aliphatic acid or an anhydride thereof to obtain a cyclotriphosphazene based epoxy phosphate aliphatic acid ester, and (iii) free radical polymerizing the cyclotriphosphazene based epoxy phosphate 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 the field of high molecular materials, in particular to a water-based emulsion composition and a preparation method thereof. BACKGROUND

[0002] In various fields of industrial production, fire prevention is an important guarantee for production and life safety. Using fireproof paint is one of the effective ways to enhance fire prevention capability.

[0003] The current fire-retardant coating generally uses high molecular polymer (or referred to as "resin") as a film-forming material. Most of the commonly used high molecular polymers are flammable by themselves, so it is necessary to add a flame retardant to provide fire-retardant performance for the coating. Commonly used flame retardants include halogen-based flame retardants, phosphorus-based flame retardants, nitrogen-based flame retardants, and silicon-based flame retardants. Among them, halogen-based flame retardants have a small amount of use, but produce toxic gases at high temperatures; phosphorus-based flame retardants do not produce toxic gases, but have a large amount of addition (generally 20%-40%); nitrogen-based flame retardants release acidic or basic gases at high temperatures, which are not friendly to coating substrates that are not resistant to acid and alkali; silicon-based flame retardants generate stable silicon dioxide carbonization layer at high temperature, have low burning speed, low heat release, low smoke, and no toxicity, etc., but have poor compatibility with substrates, and are easy to migrate and leach from the high molecular film layer, reducing the long-term fire-retardant efficiency of the coating. In addition, the addition of flame retardants also worsens the water resistance and salt mist resistance of the coating (or high molecular film layer), and additionally increases the cost. In order to alleviate or avoid the above problems, technical personnel have developed some high molecular polymers with certain fire-retardant properties, but these high molecular polymers either have insufficient water resistance, salt mist resistance, or the carbon layer produced after burning is not dense and has a low expansion height, resulting in unsatisfactory fire resistance.

[0004] In addition, most of the existing polymer emulsions with fire-retardant performance are solvent-based, which are not environmentally friendly, so water-based emulsions have received more attention. However, in the existing water-based fire-retardant polymer emulsions, the protective performance of the paint film formed by the acrylic emulsion is not good, and the epoxy resin emulsion is mostly a two-component system, which is inconvenient to use and has a short operation window. Moreover, the fire-retardant properties of these two resins are limited, and a large amount of flame retardant still needs to be added to achieve the desired fire-retardant effect.

[0005] It can be seen that the existing fire-retardant coating film-forming materials have both advantages and disadvantages, and it is difficult to balance various desired properties. With the increasing demand for high-performance coatings with high fire-retardant efficiency, strong durability, low heat production during combustion, and low release of smoke and toxic gases, their application has encountered more and more restrictions.

[0006] Therefore, there is a need in the art for a film-forming material that can overcome one or more of the above-mentioned deficiencies and have more balanced properties. SUMMARY

[0007] In view of the above needs, the present invention provides an aqueous emulsion composition and a method for preparing the same, and use of the same as a fire-retardant coating. The present invention also provides a modified epoxy resin and a method for preparing the same.

[0008] In one aspect of the present invention, there is provided an aqueous emulsion composition comprising:

[0009] (A) a nitrogen and phosphorus containing modified epoxy resin prepared by a method comprising:

[0010] (i) esterifying a cyclotriphosphazene-based epoxy resin of Formula I with phosphoric acid to obtain a cyclotriphosphazene-based epoxy phosphonate,

[0011]

[0012] wherein,

[0013] R1is -O-Ph-CH2- wherein O is single-bonded to P in the cyclotriphosphazene group,

[0014] R is wherein the ** end is single-bonded to the epoxy methylene moiety, the * end is single-bonded to oxygen, and n = 1, 2, 3, 4, 5, or 6;

[0015] (ii) esterifying the cyclotriphosphazene-based epoxy phosphonate with a C3-6unsaturated fatty acid or an anhydride thereof to obtain a cyclotriphosphazene-based epoxy phosphonate fatty acid ester, and

[0016] (iii) free-radically 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;

[0017] (B) an aqueous silica sol.

[0018] In another aspect of the present invention, there is provided a method for preparing an aqueous emulsion composition comprising: (1) preparing a nitrogen and phosphorus containing modified epoxy resin comprising:

[0019] (i) esterifying a cyclotriphosphazene-based epoxy resin of Formula I with phosphoric acid to obtain a cyclotriphosphazene-based epoxy phosphonate,

[0020]

[0021] wherein,

[0022] R1is -O-Ph-CH2- wherein O is single-bonded to P in the cyclotriphosphazene group,

[0023] 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,

[0024] n = 1, 2, 3, 4, 5, or 6;

[0025] (ii) esterifying the cyclotriphosphazene-based epoxy phosphate ester with a C3-6 unsaturated fatty acid or an acid anhydride thereof to obtain a cyclotriphosphazene-based epoxy phosphoric acid fatty acid ester, and

[0026] (iii) subjecting the cyclotriphosphazene-based epoxy phosphoric acid 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;

[0027] (2) adding an aqueous silica sol to the nitrogen- and phosphorus-containing modified epoxy resin under stirring, and then continuing to maintain stirring until a uniformly dispersed emulsion is obtained.

[0028] In yet another aspect of the present application, a modified epoxy resin is provided, which is prepared by a method comprising the steps of:

[0029] (i) esterifying a cyclotriphosphazene-based epoxy resin of Formula I with phosphoric acid to obtain a cyclotriphosphazene-based epoxy phosphate ester,

[0030]

[0031] wherein the ** end is connected to the epoxymethylene moiety with a single bond and the * end is connected to oxygen with a single bond,

[0032] R1is -O-Ph-CH2- wherein O is connected to P in the cyclotriphosphazene group with a single bond,

[0033] 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,

[0034] n = 1, 2, 3, 4, 5, or 6;

[0035] (ii) esterifying the cyclotriphosphazene-based epoxy phosphate ester with a C3-6 unsaturated fatty acid or an acid anhydride thereof to obtain a cyclotriphosphazene-based epoxy phosphoric acid fatty acid ester, and

[0036] (iii) subjecting the cyclotriphosphazene-based epoxy phosphoric acid 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.

[0037] In another aspect of the present application, there is provided a use of the aqueous emulsion composition of the present application for preparing an ultra-thin water-based intumescent fire-retardant coating.

[0038] The aqueous emulsion composition of the present application can overcome at least one of the drawbacks of the prior art and has more balanced properties in all aspects. DETAILED DESCRIPTION

[0039] Embodiments of the aqueous emulsion composition of the present application, the method for preparing the same, and the modified epoxy resin and the method for preparing the same will be described in detail hereinafter. However, there can be cases where unnecessary detailed descriptions are omitted. For example, there can be cases where detailed descriptions of matters well known in the art, repeated descriptions of substantially identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the following description is provided so that those skilled in the art can fully understand the present application, and is not intended to limit the subject matter recited in the claims.

[0040] The ranges disclosed herein are defined by the lower and upper limits of the range in the form of a range, and the given range is defined by selecting one lower limit and one upper limit, and the selected lower limit and upper limit define the boundaries of the particular range. The ranges defined in this manner can include or exclude the end values, and can be arbitrarily combined, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. In addition, if a minimum range value of 1 and 2 is listed, and if a maximum range value of 3, 4, and 5 is listed, the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In the present application, unless otherwise stated, a numerical range "a-b" indicates a shorthand for any real combination of integers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed herein, and "0-5" is merely a shorthand for these numerical combinations. In addition, when it is stated that a parameter is an integer ≥ 2, it is equivalent to disclose that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0041] If not specifically stated, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions. If not specifically stated, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0042] If not otherwise specified, all steps of the present application can be performed in any order, preferably in the order as specified. For example, the method comprising steps (a) and (b) means that the method can comprise steps (a) and (b) in the order as specified, or steps (b) and (a) in the order as specified. For example, the method comprising step (c) 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.

[0043] If not otherwise specified, the terms "comprising" and "including" as used in the present application are open-ended and also include closed-ended. For example, the terms "comprising" and "including" can mean that further components not listed can also be included, or only the listed components can be included.

[0044] If not otherwise specified, the term "or" in the present application is inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, any of the following satisfy the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0045] In the present text, the terms have the generally understood and accepted meaning in the art, if not specifically explained otherwise. In the present text, the substances, if not specifically mentioned otherwise, are the commercially available products.

[0046] The present application relates to an aqueous emulsion composition comprising the following components:

[0047] (A) a modified epoxy resin containing nitrogen and phosphorus, which is prepared by a process comprising the following steps:

[0048] (i) esterifying a cyclotriphosphazene-based epoxy resin of formula I with phosphoric acid to obtain a cyclotriphosphazene-based epoxy phosphonate,

[0049]

[0050] wherein

[0051] R1is -O-Ph-CH2-, wherein O is connected to P in the cyclotriphosphazene group with a single bond,

[0052] 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,

[0053] n = 1, 2, 3, 4, 5 or 6;

[0054] (ii) esterifying the cyclotriphosphazene-based epoxy phosphate with a C3-6 unsaturated fatty acid or an anhydride thereof to obtain a cyclotriphosphazene-based epoxy phosphate fatty acid ester, and

[0055] (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;

[0056] (B) an aqueous silica sol.

[0057] Without being bound by any theory, the aqueous emulsion composition of the present application, after film formation, has good fire retardancy (with a high fire resistance limit), good water and salt mist resistance (and also has some corrosion protection effect on the substrate), good adhesion to the substrate, and other properties. At the same time, the film layer formed by the emulsion of the present application can form a dense carbon layer on the surface of the coated substrate after burning. In addition, the inventors have also noticed that the film layer releases less heat during burning and produces non-combustible gases. Without being bound by any theory, these may all contribute to reducing the impact of high-temperature burning on the substrate. The emulsion of the present application itself has certain fire retardancy, and does not need to be added in a particularly large amount of flame retardant, which helps to avoid or reduce the adverse effects brought by the flame retardant.

[0058] In addition, the aqueous emulsion composition of the present application is a single-component emulsion, which can form a film after coating by drying without the need for the addition of a film-forming aid (such as a curing agent) to assist. Therefore, in practical applications, due to the absence of a curing agent, the composition of the present application is easy and simple to operate, has a long window period, and is also beneficial for long-term storage.

[0059] Herein, "single-component emulsion" means an emulsion that does not require the additional addition of a film-forming aid (such as a curing agent). Such an emulsion can be used directly or after dilution with water, and it can form a film during the water evaporation and drying process without the need for a film-forming aid. Similarly, "two-component emulsion" means an emulsion that requires the assistance of a film-forming aid to form a film. Herein, any expression relating to "single-component" or "two-component" is understood in the above similar meaning.

[0060] Herein, "film formation" refers to the formation of a film layer on the surface of a substrate by an emulsion or coating through a physical process (for example, water evaporation).

[0061] After film formation, the composition of the present application is still in a physical mixing state of components (A) and (B), that is, the two do not undergo a chemical reaction during the film formation process.

[0062] As described above, the nitrogen- and phosphorus-containing modified epoxy resin of the present application is obtained from a method comprising the following steps:

[0063] (i) esterifying a cyclotriphosphazene-based epoxy resin of Formula I with phosphoric acid to obtain a cyclotriphosphazene-based epoxy phosphonate,

[0064]

[0065] wherein,

[0066] R1is -O-Ph-CH2- wherein O is connected to P in the cyclotriphosphazene group with a single bond,

[0067] 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,

[0068] n = 1, 2, 3, 4, 5, or 6;

[0069] (ii) esterifying the cyclotriphosphazene-based epoxy phosphonate with a C3-6unsaturated fatty acid or an acid anhydride thereof to obtain a tricyclophosphazene-based epoxy phosphonate fatty acid ester, and

[0070] (iii) free-radically polymerizing the tricyclophosphazene-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.

[0071] In some embodiments, the molar ratio of the molar amount of the cyclotriphosphazene-based epoxy resin to the molar amount of phosphoric acid in step (i) is from 7 to 1:1 and is not 1:1. Without being bound by any theory, the molar ratio of the epoxy groups to phosphoric acid in this range helps to improve the flame retardancy, fire resistance, and char yield after burning of the film layer formed from the emulsion composition, and improves its adhesion to the substrate, and improves the water resistance, salt fog resistance of the film layer. In some embodiments, the molar ratio is preferably from 5 to 1:1 and is not 1:1; more preferably from 3.5 to 1.1:1. In some embodiments, the molar ratio can be 6.78:1, 4.55:1, 3.48:1, 2.27:1, 1.51:1, or 1.2:1, or the ratio can be in a range between any two of the foregoing.

[0072] 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. Reducing the amount of water in the reaction system facilitates the esterification reaction. 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.

[0073] In some embodiments, n in Formula I is 1 or 2.

[0074] 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 completion. After the reaction is complete, the solvent is removed to obtain the epoxy phosphonate.

[0075] The completion 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 a decrease in the acid value is no longer observed, which indicates that the reaction has reached completion. The acid value can be determined in a manner known to those skilled in the art.

[0076] 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 mixtures of any two or more thereof; preferably a mixture of acetone and butanone.

[0077] In some embodiments, the esterification reaction of step (i) is carried out at a temperature of 50-60 °C, preferably 55 °C.

[0078] 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.

[0079] 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)).

[0080] 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.

[0081] In some embodiments, the esterification reaction of step (ii) is carried out at a temperature of 120-150 °C.

[0082] 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.

[0083] 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 can be one or more alcohol ether solvents, preferably selected from at least one of propylene glycol monobutyl ether, n-butanol, ethylene glycol monobutyl ether, glycerol methyl ether, propylene glycol methyl ether, and isobutyl alcohol, more preferably selected from propylene glycol methyl ether, ethylene glycol monobutyl ether, n-butanol, or a mixture of two or more of the foregoing. In some embodiments, the organic solvent is added such that the solid content of the resulting tricyclophosphazene-based epoxy phosphonolipid fatty acid ester solution is from 55 wt% to 90 wt%, preferably from 60 wt% to 80 wt%.

[0084] 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.

[0085] 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. Still 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.

[0086] Herein, “(meth)acrylic acid” means acrylic acid and / or methacrylic acid.

[0087] 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).

[0088] In some embodiments, the reaction temperature of step (iii) is 85-130°C.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] After the above-mentioned 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.

[0093] In some embodiments, the composition of the present application comprises 40% to 50%, preferably 43% to 49%, of component (A), based on the total weight of the composition.

[0094] In this context, "water-based silica sol" refers to a colloidal solution in which colloidal silica particles are uniformly dispersed in water.

[0095] 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 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.

[0096] As described above, the aqueous silica sol comprises silica. In some embodiments, the composition comprises 3% to 6%, preferably 3.5% to 6%, of silica based on the total weight of the composition.

[0097] The composition of the present application does not comprise an emulsification aid or a film-forming aid, such as an emulsifier, a curing agent, and the like. The composition of the present application is an aqueous dispersion and can form a single-component emulsion, which can form a film without a film-forming aid.

[0098] In some embodiments, the aqueous emulsion composition of the present application consists of components (A) and (B).

[0099] The present application also provides a method for preparing an aqueous emulsion composition, comprising the following steps:

[0100] (1) preparing a modified epoxy resin containing nitrogen and phosphorus, comprising:

[0101] (i) esterifying a cyclotriphosphazene-based epoxy resin of Formula I with phosphoric acid to obtain a cyclotriphosphazene-based epoxy phosphonate,

[0102]

[0103] wherein,

[0104] R1is -O-Ph-CH2-, wherein O is connected to P in the cyclotriphosphazene group by a single bond, and R is wherein the ** end is connected to the epoxy methylene moiety by a single bond, the * end is connected to oxygen by a single bond, and n = 1, 2, 3, 4, 5, or 6;

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

[0106] (iii) subjecting the tricyclic phosphazene-based epoxy phosphonolipid fatty acid ester to a free 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 to the nitrogen and phosphorus containing modified epoxy resin, and then continuing to maintain stirring until a uniformly dispersed emulsion is obtained.

[0108] The various descriptions above for the composition of the present application apply to the corresponding content / features in the method of preparation below; and vice versa.

[0109] In the method of the present application, the preparation of the tricyclic phosphazene-based epoxy resin of formula I (PN-EP) employed 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:

[0110] In the first step, 274 g of sodium (70 wt% dilution in oil) and 976 g of 4-hydroxybenzaldehyde solution (500 mL THF) were mixed in a reactor to prepare a suspension of sodium 4-aldehyde phenoxy in dry THF under mechanical stirring, reflux condensation, and nitrogen inlet. 348 g of hexachlorocyclotriphosphazene (N3P3Cl6) was 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, a light brown hexakis(4-aldehyde-phenoxy)-cyclotriphosphazene (PN-CHO) powder was obtained with a yield of 70.5 wt%;

[0111] In the second step, NaBH4 (56 g) was added to the reactor containing 200 g of PN-CHO solution in a 500 mL THF / methanol mixture. It was stirred at room temperature for 14 h and recrystallized with 90 vol% ethanol to obtain hexakis(4-hydroxyphenoxy)-cyclotriphosphazene (PN-OH) as a white solid with a yield of 79.6 wt%;

[0112] In the third step, 1000 g of epoxy resin E44 was added to the reactor, stirred at 120°C for 2 h under nitrogen atmosphere, then 318 g of PN-OH with an equivalent ratio of 1:14 to DGEBA and an appropriate amount of triphenylphosphine (0.3 wt%) as catalyst were added. The reaction mixture was kept at 175°C for 5 h.

[0113] The PN-EP used in the embodiments of the present application was prepared as described above.

[0114] In the present application, the epoxy resin used for preparing the PN-EP can be any bisphenol-based epoxy resin known in the art, in addition to the epoxy resin E44 described above. Preferably, the PN-EP of the present application is prepared from bisphenol A epoxy resin. In some embodiments, the PN-EP of the present application is prepared from low molecular weight bisphenol A epoxy resin, preferably epoxy resin E44 or E51, more preferably E44. When the epoxy resin used for preparing the cyclotriphosphazene-based epoxy resin of formula I is epoxy resin E44 or E51, n < 2. In other words, n in formula I is preferably 1 or 2 in the present application.

[0115] The above preparation process can be exemplarily described by the following synthetic route:

[0116]

[0117] In some embodiments, in step (2) of the method of the present application, the modified epoxy resin obtained in step (1) above is maintained 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 continued under high-speed stirring, and after uniform dispersion, the emulsion mixture of the present application is obtained.

[0118] In the present application, the completion of phase inversion is determined as follows: in the initial stage, after the addition of the aqueous silica sol, the viscosity increases and the system becomes turbid; as the aqueous silica sol is further added, the viscosity continues to increase and the system gradually becomes semi-transparent or visually uniform. At this point, it can be considered that the phase inversion is basically completed, but the viscosity of the system is still relatively high. After the phase inversion is completed, the remaining aqueous silica sol can be further added to adjust the viscosity of the system to the desired state.

[0119] In some embodiments, the stirring speed can be higher than 1000 r / min, preferably 2000-3000 r / min.

[0120] During the stirring and dispersion process, the state of the emulsion should be observed; generally, when uniform dispersion is observed, the dispersion can be ended. In some embodiments, the dispersion time is 1-2 hours. This is conducive to obtaining a uniformly dispersed, fine and stable emulsion.

[0121] In some embodiments, the emulsion composition of the present application has a solid content of 20% to 40%. This is advantageous for the emulsion system to be stable uniform and have proper viscosity.

[0122] The present application also provides a modified epoxy resin prepared by a method comprising the steps of:

[0123] (i) esterifying a cyclotriphosphazene-based epoxy resin of Formula I with phosphoric acid to obtain a cyclotriphosphazene-based epoxy phosphonate,

[0124]

[0125] wherein,

[0126] R1is -O-Ph-CH2- wherein O is connected to P in the cyclotriphosphazene group with a single bond,

[0127] 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,

[0128] n = 1, 2, 3, 4, 5 or 6;

[0129] (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

[0130] (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.

[0131] In some embodiments, n in Formula I is 1 or 2.

[0132] The present application provides the use of the aqueous emulsion composition as described above for the preparation of a thin type waterborne intumescent fireproof coating. Preferably, the use of the aqueous emulsion composition of the present application for the preparation of an ultra-thin type waterborne intumescent fireproof coating. The aqueous emulsion composition of the present application is used as a film-forming component in the fireproof coating.

[0133] In this context, "intumescent fire-retardant coating" means that the coating formed by the coating will expand under the action of fire or high temperature, forming a carbon layer several times thicker than the original coating, thus more effectively blocking the continuous action of external heat source or burning flame on the substrate. According to GB 14907-2002, thin fire-retardant coating is a fire-retardant coating with a coating thickness of 3-7 mm, and ultra-thin fire-retardant coating is a fire-retardant coating with a coating thickness of less than 3 mm. In this context, the term "thin coating" and its similar terms cover thin fire-retardant coating and ultra-thin fire-retardant coating.

[0134] Examples

[0135] The application will be further described below in conjunction with examples:

[0136] Example 1

[0137] 1. Aqueous silica sol:

[0138] Take 100 g of commercially available aqueous silica sol (S-830 of Hubei Zhenghe Technology Co., Ltd., solid content 30 wt%, same below) and add 220 g of deionized water to disperse uniformly under ultrasonic, to obtain the aqueous silica sol used herein.

[0139] 2. Preparation of nitrogen and phosphorus-containing modified epoxy resin of the application:

[0140] Take 330 g of cyclotriphosphazene-based epoxy resin (PN-EP) prepared as described above and place it in a four-necked flask, then add a mixed solution of 40 g of butanone and 60 g of acetone to dissolve the PN-EP, with a temperature of 55°C, then add 1.2 g of phosphotungstic acid, and then add dropwise a mixture of 20 g of 85% phosphoric acid and 30 g of acetone, wherein the molar ratio of the molar amount of epoxy groups in PN-EP to the molar amount of phosphoric acid is 3.48:1; after the dropwise addition is completed, measure the acid value every half hour until the acid value no longer changes, which is the reaction endpoint. Then remove the acetone and butanone solvents in the system by vacuum rotary evaporation to obtain a cyclotriphosphazene-based epoxy phosphate ester. Then raise the temperature to 130°C, add 35 g of methacrylic acid and 2 g of triphenylphosphine, and maintain the reaction temperature at 130°C until the acid value is <10 mg KOH / g, the esterification reaction is complete, and then add 200 g of propylene glycol methyl ether to obtain a cyclotriphosphazene-based epoxy phosphate methacrylate.

[0141] Take another 150 g of the above tricyclic phosphazene-based epoxy phosphonic acid methacrylate and add it to a four-necked flask containing a stirrer, condenser, thermometer, and dropping funnel, with the temperature at 85°C. Mix 80 g of vinyl acetate, 8 g of isooctyl acrylate, 12 g of vinyl versatate, 10 g of acrylic acid, and 4 g of BPO uniformly, and drop the mixture into the tricyclic phosphazene-based epoxy phosphonic acid methacrylate at a uniform speed, control the speed to complete the drop in 3 h, then increase the temperature to 100°C, and keep the temperature for 3 h. After the incubation is completed, reduce the temperature to 50°C, add 14 g of triethylamine for neutralization, keep the temperature at 50°C, and stir at a high speed for 1 h.

[0142] 3. Preparation of the composition of the present application:

[0143] Cool the above neutralized material to 35°C, then add water-based silica sol under high-speed dispersion, complete the drop in 30 min, then continue to disperse for 40 min, and then discharge.

[0144] Example 2

[0145] 1. Water-based silica sol:

[0146] Take 80 g of commercially available water-based silica sol (solid content 30 wt%) and add 240 g of deionized water to disperse uniformly under ultrasonic, to obtain the water-based silica sol used herein.

[0147] 2. Preparation of the nitrogen and phosphorus-containing modified epoxy resin of the present application:

[0148] Take 330 g of PN-EP and add it to a four-necked flask, then add 50 g of butanone and 50 g of acetone mixed solution to dissolve the PN-EP, with the temperature at 55°C, then add 2 g of phosphotungstic acid, and then drop 30 g of 85% phosphoric acid and 45 g of acetone mixture, wherein the molar ratio of the molar amount of the epoxy groups in the PN-EP to the molar amount of the phosphoric acid is 2.27:1; measure the acid value every half hour after the drop is completed until the acid value no longer changes as the reaction endpoint. Then remove the acetone and butanone solvents in the system by vacuum rotary evaporation to obtain a tricyclic phosphazene-based epoxy phosphonate. Then increase the temperature to 125°C, add 20 g of acrylic acid and 1.5 g of monobutyl tin oxide, keep the reaction temperature at 125°C until the acid value is <10 mg KOH / g, the esterification reaction is completed, reduce the temperature, and add 200 g of ethylene glycol butyl ether to obtain a tricyclic phosphazene-based epoxy phosphonic acid acrylate.

[0149] Take another 150 g of the above tricyclic phosphazene-based epoxy phosphonic acid acrylate and add it to a four-necked flask containing a stirrer, condenser, thermometer, and dropping funnel, with the temperature being 95°C. Weigh 60 g of vinyl acetate, 20 g of styrene, 18 g of butyl acrylate, 8 g of vinyl versatate, 12 g of methacrylic acid, and 5 g of BPO, mix them well, and then add the mixture to the tricyclic phosphazene-based epoxy phosphonic acid acrylate at a constant rate. Control the rate of addition to complete the addition in 3 hours, then increase the temperature to 115°C, and maintain this temperature for 3 hours. After the reaction is complete, reduce the temperature to 50°C, add 15 g of triethylamine to neutralize the product, and then maintain the temperature at 50°C and stir at a high speed for 1 hour.

[0150] 3. Preparation of the composition of the present application:

[0151] Cool the neutralized product to 35°C, then add the aqueous silica sol dropwise under high-speed dispersion, and complete the addition in 30 minutes. Continue to disperse for another 50 minutes, and then discharge the product.

[0152] Example 3

[0153] 1. Aqueous silica sol:

[0154] Take 120 g of commercially available aqueous silica sol (solid content 30 wt%) and add 200 g of deionized water to disperse it uniformly under ultrasonic waves to obtain the aqueous silica sol used herein.

[0155] 2. Preparation of the nitrogen- and phosphorus-containing modified epoxy resin of the present application:

[0156] Take 330 g of PN-EP and add it to a four-necked flask, then add a mixture of 50 g of butanone and 50 g of acetone to dissolve the PN-EP, with the temperature being 55°C. Add 0.8 g of phosphotungstic acid, then add a mixture of 15 g of 85% phosphoric acid and 25 g of acetone dropwise, with the molar ratio of the moles of epoxy groups in the PN-EP to the moles of phosphoric acid being 4.55:1. After the addition is complete, measure the acid value every half hour until the acid value no longer changes, which is the reaction endpoint. Then remove the acetone and butanone solvents in the system by vacuum rotary evaporation to obtain a tricyclic phosphazene-based epoxy phosphonate. Then increase the temperature to 140°C, add 40 g of methacrylic acid and 2.5 g of monobutyl tin oxide, and maintain the reaction temperature at 140°C until the acid value is <10 mg KOH / g, which indicates that the esterification reaction is complete. Reduce the temperature and add 100 g of ethylene glycol butyl ether and 100 g of n-butanol to obtain tricyclic phosphazene-based epoxy phosphonic acid methacrylate.

[0157] Take 150 g of the above tricyclic phosphazene-based epoxy phosphonic acid methacrylate, add it to a four-necked flask containing a stirrer, condenser, thermometer, and dropping funnel, and heat it to 90°C. Mix 70 g of vinyl acetate, 10 g of methyl methacrylate, 15 g of ethyl acrylate, 12 g of vinyl versatate, 12 g of acrylic acid, and 5 g of BPO uniformly, and add the mixture to the tricyclic phosphazene-based epoxy phosphonic acid methacrylate at a constant rate. Control the rate of addition to complete the addition in 3 hours, then increase the temperature to 105°C, and maintain this temperature for 3 hours. After the reaction is complete, cool the mixture to 50°C, add 15 g of DMEA to neutralize it, and maintain the temperature at 50°C while stirring the mixture at a high speed for 1 hour.

[0158] 3. Preparation of the composition of the present application:

[0159] Cool the mixture to 35°C, then add the aqueous silica sol dropwise while dispersing it at a high speed. Complete the addition in 30 minutes, then continue to disperse the mixture for 50 minutes, and then discharge the product.

[0160] Example 4

[0161] 1. Aqueous silica sol:

[0162] Take 100 g of commercially available aqueous silica sol (solid content: 30 wt%) and add 240 g of deionized water to it. Disperse the mixture uniformly using ultrasonic waves to obtain the aqueous silica sol used in this example.

[0163] 2. Preparation of the nitrogen- and phosphorus-containing modified epoxy resin of the present application:

[0164] Take 330 g of PN-EP and add it to a four-necked flask. Then add a mixture of 50 g of butanone and 50 g of acetone to dissolve the PN-EP. The temperature is 55°C. Add 2 g of phosphotungstic acid, then add a mixture of 56 g of 85% phosphoric acid and 45 g of acetone dropwise. The molar ratio of the moles of epoxy groups in the PN-EP to the moles of phosphoric acid is 1.2:1. Measure the acid value every half hour after the addition is complete until the acid value no longer changes, which is the end point of the reaction. Then remove the acetone and butanone solvents in the system by vacuum distillation to obtain a tricyclic phosphazene-based epoxy phosphonate. Then increase the temperature to 125°C, add 8 g of acrylic acid and 1.5 g of monobutyl tin oxide, and maintain the reaction temperature at 125°C until the acid value is <10 mg KOH / g, which indicates that the esterification reaction is complete. Then cool the mixture, add 200 g of ethylene glycol butyl ether, and obtain a tricyclic phosphazene-based epoxy phosphonic acid acrylate.

[0165] Take another 150 g of the above tricyclic phosphazene-based epoxy phosphonic acid acrylate and add it to a four-necked flask containing a stirrer, condenser, thermometer, and dropping funnel, with the temperature being 95°C. Weigh 50 g of vinyl acetate, 15 g of styrene, 18 g of butyl acrylate, 10 g of vinyl versatate, 12 g of methacrylic acid, and 5 g of BPO, mix them well, and then add the mixture to the tricyclic phosphazene-based epoxy phosphonic acid acrylate at a constant rate. Control the rate of addition to complete the addition in 3 hours, then increase the temperature to 115°C, and maintain this temperature for 3 hours. After the reaction is complete, reduce the temperature to 50°C, add 15 g of triethylamine to neutralize the product, and then maintain the temperature at 50°C and stir at a high speed for 1 hour.

[0166] 3. Preparation of the composition of the present application:

[0167] Cool the neutralized product to 35°C, then add the aqueous silica sol under high-speed dispersion, and complete the addition in 30 minutes. Continue to disperse for another 50 minutes, and then discharge the product.

[0168] Example 5

[0169] 1. Aqueous silica sol:

[0170] Take 100 g of commercially available aqueous silica sol (solid content 30 wt%) and add 240 g of deionized water to disperse it uniformly under ultrasonic waves to obtain the aqueous silica sol used herein.

[0171] 2. Preparation of the nitrogen and phosphorus-containing modified epoxy resin of the present application:

[0172] Take 330 g of PN-EP and add it to a four-necked flask, then add a mixture of 50 g of butanone and 50 g of acetone to dissolve the PN-EP, with the temperature being 55°C. Add 2 g of phosphotungstic acid, then add a mixture of 45 g of 85% phosphoric acid and 45 g of acetone dropwise, with the molar ratio of the molar amount of the epoxy groups in the PN-EP to the molar amount of the phosphoric acid being 1.51:1. Measure the acid value every half hour after the addition is complete until the acid value no longer changes, which is the reaction endpoint. Then remove the acetone and butanone solvents in the system by vacuum rotary evaporation to obtain a tricyclic phosphazene-based epoxy phosphonate. Then increase the temperature to 125°C, add 15 g of acrylic acid and 1.5 g of monobutyl tin oxide, and maintain the reaction temperature at 125°C until the acid value is <10 mg KOH / g, which indicates that the esterification reaction is complete. Reduce the temperature and add 200 g of ethylene glycol butyl ether to obtain the tricyclic phosphazene-based epoxy phosphonic acid acrylate.

[0173] Take another 150 g of the above tricyclic phosphazene-based epoxy phosphonic acid acrylate and add it to a four-necked flask containing a stirrer, condenser, thermometer, and dropping funnel, with the temperature being 95°C. Weigh 70 g of vinyl acetate, 15 g of styrene, 15 g of butyl acrylate, 12 g of vinyl versatate, 12 g of methacrylic acid, and 5 g of BPO, mix them well, and then add the mixture to the tricyclic phosphazene-based epoxy phosphonic acid acrylate at a constant rate. Control the rate of addition to complete the addition in 3 hours, then increase the temperature to 115°C, and maintain this temperature for 3 hours. After the reaction is complete, reduce the temperature to 50°C, add 15 g of triethylamine to neutralize the product, and then maintain the temperature at 50°C and stir at a high speed for 1 hour.

[0174] 3. Preparation of the composition of the present application:

[0175] Cool the neutralized product to 35°C, then add the aqueous silica sol under high-speed dispersion, and complete the addition in 30 minutes. Continue to disperse for another 50 minutes, and then discharge the product.

[0176] Example 6

[0177] 1. Aqueous silica sol:

[0178] Take 100 g of commercially available aqueous silica sol (solid content 30 wt%) and add 240 g of deionized water to disperse it uniformly under ultrasonic waves to obtain the aqueous silica sol used herein.

[0179] 2. Preparation of the nitrogen and phosphorus-containing modified epoxy resin of the present application:

[0180] Take 330 g of PN-EP and add it to a four-necked flask, then add a mixture of 50 g of butanone and 50 g of acetone to dissolve the PN-EP, with the temperature being 55°C. Add 2 g of phosphotungstic acid, then add a mixture of 10 g of 85% phosphoric acid and 45 g of acetone dropwise, with the molar ratio of the molar amount of the epoxy groups in the PN-EP to the molar amount of the phosphoric acid being 6.78:1. After the addition is complete, measure the acid value every half hour until the acid value no longer changes, which is the reaction endpoint. Then remove the acetone and butanone solvents in the system by vacuum rotary evaporation to obtain a tricyclic phosphazene-based epoxy phosphonate. Then increase the temperature to 125°C, add 38 g of acrylic acid and 1.5 g of monobutyl tin oxide, and maintain the reaction temperature at 125°C until the acid value is <10 mg KOH / g, indicating that the esterification reaction is complete. Reduce the temperature and add 200 g of ethylene glycol butyl ether to obtain the tricyclic phosphazene-based epoxy phosphonic acid acrylate.

[0181] Take 150 g of the above tricyclic phosphazene-based epoxy propylene acrylic acid ester and add it to a four-necked flask containing a stirrer, condenser, thermometer, and dropping funnel, with the temperature being 95°C. Weigh 80 g of vinyl acetate, 25 g of styrene, 18 g of butyl acrylate, 8 g of vinyl versatate, 12 g of methacrylic acid, and 5 g of BPO, mix them uniformly, and drop the mixture into the tricyclic phosphazene-based epoxy propylene acrylic acid ester at a uniform speed, control the speed, and complete the dropping in 3 hours, then increase the temperature to 115°C, and keep it for 3 hours, after which the temperature is decreased to 50°C, 15 g of triethylamine is added for neutralization, and then the temperature is kept at 50°C and high-speed stirring is performed for 1 hour.

[0182] 3. Preparation of the composition of the present application:

[0183] The neutralized material is cooled to 35°C, then water-based silica sol is added dropwise under high-speed dispersion, the dropping is completed in 30 minutes, then dispersion is continued for 50 minutes, and the product can be discharged.

[0184] Comparative Example 1 - Emulsion composition containing a modified epoxy resin not modified with phosphoric acid

[0185] 1. Water-based silica sol:

[0186] Take 100 g of commercially available water-based silica sol (solid content 30% by weight), add 220 g of deionized water, and ultrasonically disperse them uniformly to obtain the water-based silica sol used herein.

[0187] 2. Preparation of the modified epoxy resin:

[0188] Take 330 g of the above-prepared PN-EP and put it into a four-necked flask, then increase the temperature to 140°C, add 50 g of methacrylic acid and 3 g of triphenylphosphine, keep the reaction temperature at 130°C until the acid value is <10 mg KOH / g, the esterification reaction is completed, and 175 g of propylene glycol methyl ether is added to obtain tricyclic phosphazene-based epoxy methacrylic acid ester.

[0189] Take 150 g of the above tricyclic phosphazene-based epoxy methacrylic acid ester and add it to a four-necked flask containing a stirrer, condenser, thermometer, and dropping funnel, with the temperature being 85°C. Weigh 80 g of vinyl acetate, 8 g of isooctyl acrylate, 12 g of vinyl versatate, 10 g of acrylic acid, and 4 g of BPO, mix them uniformly, drop the mixture into the tricyclic phosphazene-based epoxy methacrylic acid ester at a uniform speed, control the speed, and complete the dropping in 3 hours, then increase the temperature to 100°C, and keep it for 3 hours, after which the temperature is decreased to 50°C, 14 g of triethylamine is added for neutralization, and 50°C is kept for high-speed stirring for 1 hour.

[0190] 3. Preparation of the composition:

[0191] The neutralized material is cooled to 35°C, then water-based silica sol is added dropwise under high-speed dispersion, and the dropping is completed in 30 min, and then dispersion is continued for 40 min, and the material can be discharged.

[0192] Comparative Example 2 - Emulsion composition without silicon

[0193] 1. Preparation of modified epoxy resin:

[0194] Take 330 g of the above-prepared PN-EP and place it in a four-necked flask, then add a mixed solution of 50 g of butanone and 50 g of acetone to dissolve the PN-EP, with a temperature of 55°C, then add 2 g of phosphotungstic acid, and then add dropwise a mixture of 30 g of 85% phosphoric acid and 45 g of acetone, measure the acid value every half hour after the dropping is completed, until the acid value no longer changes, as the reaction endpoint. Then remove the acetone and butanone solvents in the system by vacuum rotary evaporation, to obtain a cyclotriphosphazene-based epoxy phosphate ester. Then raise the temperature to 125°C, add 20 g of acrylic acid, 1.5 g of monobutyl tin oxide, maintain the reaction temperature at 125°C, until the acid value is <10 mg KOH / g, the esterification reaction is complete, and then cool and add 200 g of ethylene glycol butyl ether, to obtain a cyclotriphosphazene-based epoxy phosphate acrylate.

[0195] Take 150 g of the above cyclotriphosphazene-based epoxy phosphate acrylate and place it in a four-necked flask containing a stirrer, condenser, thermometer, and dropping funnel, with a temperature of 95°C. Weigh 60 g of vinyl acetate, 20 g of styrene, 18 g of butyl acrylate, 8 g of vinyl versatate, 12 g of methyl methacrylate, and 5 g of BPO, mix them uniformly, and then add the mixture to the cyclotriphosphazene-based epoxy phosphate acrylate at a uniform speed, control the speed, and complete the dropping in 3 h, then raise the temperature to 115°C, maintain the temperature for 3 h, then cool to 50°C, add 15 g of triethylamine to neutralize, and maintain high-speed stirring at 50°C for 1 h.

[0196] 2. Preparation of the composition:

[0197] Cool the above neutralized material to 35°C, then add 340 g of deionized water dropwise under high-speed dispersion, complete the dropping in 30 min, then continue to disperse for 50 min, and the material can be discharged.

[0198] Comparative Example 3 - Emulsion composition without nitrogen

[0199] 1. Water-based silica sol:

[0200] Take 100 g of commercially available water-based silica sol (solid content 30% by weight), add 220 g of deionized water, and ultrasonically disperse them uniformly, to obtain the water-based silica sol used here.

[0201] 2. Preparation of modified epoxy resin:

[0202] Take 132 g of epoxy resin E44 into a four-necked flask, then add 20 g of butanone and 20 g of acetone mixed solution to dissolve the epoxy resin, the temperature is 55°C, add 0.8 g of phosphotungstic acid, then add 15 g of 85% phosphoric acid and 25 g of acetone mixture drop by drop, measure the acid value every half hour after the dropwise addition is completed until the acid value no longer changes as the reaction endpoint. Then remove the acetone and butanone solvents in the system by vacuum rotary evaporation to obtain a phosphoric acid modified epoxy resin. Then the temperature is raised to 140°C, 40 g of methacrylic acid and 2.5 g of monobutyl tin oxide are added, and the reaction temperature is maintained at 140°C until the acid value is <10 mg KOH / g, and the esterification reaction is complete. Cool down and add 25 g of ethylene glycol butyl ether and 25 g of n-butanol to obtain an epoxy phosphoric acid methacrylate.

[0203] Take another 150 g of the above epoxy phosphoric acid methacrylate and add it to a four-necked flask containing a stirrer, condenser, thermometer, and dropping funnel, and the temperature is 90°C. Weigh 70 g of vinyl acetate, 10 g of methyl methacrylate, 15 g of ethyl acrylate, 12 g of vinyl versatate, 12 g of acrylic acid, and 5 g of BPO, mix them evenly, and add the mixture to the epoxy phosphoric acid methacrylate at a constant speed. Control the speed to complete the dropwise addition in 3 h, then raise the temperature to 105°C and maintain it for 3 h. After the incubation is complete, cool down to 50°C and add 15 g of DMEA for neutralization. Maintain high-speed stirring at 50°C for 1 h.

[0204] 3. Preparation of the composition:

[0205] Cool the above neutralized material to 35°C, then add water-based silica sol dropwise under high-speed dispersion, and complete the dropwise addition in 30 min. Continue to disperse for 50 min, and then discharge.

[0206] Comparative Example 4 - Emulsion composition without nitrogen, phosphorus, and silicon

[0207] 1. Preparation of modified epoxy resin:

[0208] Take 132 g of epoxy resin E44 into a four-necked flask, then raise the temperature to 140°C, add 50 g of methacrylic acid and 3 g of monobutyl tin oxide, and maintain the reaction temperature at 140°C until the acid value is <10 mg KOH / g, and the esterification reaction is complete. Cool down and add 25 g of ethylene glycol butyl ether and 25 g of n-butanol to obtain an epoxy methacrylate;

[0209] Take another 150 g of the above epoxy methacrylate and add it to a four-necked flask containing a stirrer, condenser, thermometer, and dropping funnel, and heat it to 90°C. Weigh 70 g of vinyl acetate, 10 g of methyl methacrylate, 15 g of ethyl acrylate, 12 g of vinyl versatate, 12 g of acrylic acid, and 5 g of BPO, mix them well, and add the mixture to the epoxy methacrylate at a constant rate. Control the rate so that the addition is completed in 3 hours. Then raise the temperature to 105°C and maintain it for 3 hours. After the incubation, lower the temperature to 50°C, and add 15 g of DMEA to neutralize it. Maintain the high-speed stirring at 50°C for 1 hour.

[0210] 2. Preparation of the composition:

[0211] Cool the neutralized material to 35°C, and then add 340 g of deionized water dropwise under high-speed dispersion. The addition is completed in 30 minutes, and then the dispersion is continued for another 50 minutes, after which the product can be discharged.

[0212] The compositions prepared in the above examples and comparative examples are respectively tested for performance according to the following methods, and the test results are summarized in Table 1 below.

[0213] Test method:

[0214] 1. Preparation of test panels: Take 2-3 mL of the emulsion and apply it to a pretreated cold-rolled steel panel using a 200-micron wire bar applicator to achieve a dry film thickness of 40 μm. Place the panel in a room with a temperature of 25°C and a humidity of 50% for 7 days before testing.

[0215] Pretreatment method: Remove oil from the steel panel with acetone, and then polish it with 320-grit sandpaper. Then wipe the panel clean with ethanol.

[0216] 2. Water resistance test: Submerge 2 / 3 of the test panel in a water tank at room temperature for 48 hours, and observe whether the paint film is blistering, rusting, or whitening.

[0217] 3. Salt spray resistance test: Perform back sealing and edge sealing on the test panel, place it in a neutral salt spray chamber, and observe and record the time at which the paint film begins to rust. The back sealing is performed by brushing a two-component waterborne epoxy coating, and the edge sealing is performed using a mixture of paraffin and rosin in a 1:1 ratio.

[0218] 4. Adhesion test: Perform the test on the test panel using the crosshatch method (according to the national standard GB / T 9286-1998 “Crosshatch method for adhesion of paint films”).

[0219] 5. Limiting Oxygen Index (LOI) Test: Resin samples with a length of (125±5) mm, a width of (10.0±0.5) mm, and a thickness of (4±0.25) mm were prepared according to GB / T2406-2009. The pretreatment method was the same as the UL94 method. The top-side ignition method was used, and the LOI value of the resin samples was determined using an HFTAⅡ oxygen indexer from PL (Physical Industries, Inc., UK). A higher limiting oxygen index indicates that the material is more difficult to burn.

[0220] 6. Fire Resistance Test: Following UL94-1996 Class V, the self-made emulsion was poured into a mold and slowly dried. The resulting resin was then cut into samples with a length of (125±5) mm, a width of (13.0±0.5) mm, and a thickness of (0.8±0.1) mm. Methane process 10 was used. 5 With a flame height of (20±1) mm and a back pressure of 10 mm water column, the flame center is placed at the midpoint of the lower edge of the sample, and the ignition time is maintained at (10±0.5) s.

[0221] 7. Thermal Analysis: The prepared emulsion was dried to obtain resin samples. Thermal analysis of the resin samples was performed using a TA Instruments Q-50 TGA analyzer. The experimental conditions were set as follows: temperature range 50–700℃, heating rate 20℃·min. -1 The atmosphere was nitrogen. The results of the thermal analysis were recorded as "carbonization rate". "Carbonization rate" is defined as the weight percentage of residual material remaining on the substrate surface after combustion, based on the weight of the film layer before combustion.

[0222] Table 1

[0223]

[0224] As shown in Table 1, the compositions of the present invention (Examples 1-6) combine the advantages of epoxy resin and acrylic resin, exhibiting good water and salt spray resistance, excellent adhesion to the substrate, and superior flame retardancy and heat resistance of the resin film itself. Furthermore, the film layer of the compositions of the present invention shows a significantly higher char formation rate after combustion compared to existing technologies. That is, the film layer formed by the compositions of the present invention creates a thicker protective layer on the substrate surface after combustion. It can be understood that, in the event of a fire, the compositions of the present invention can better protect the substrate (e.g., steel substrate) from high-temperature damage, prolonging the time required for it to reach its deformation temperature, resulting in better fire resistance and flame retardancy.

[0225] 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 application be construed as including any patently suspicious variation, use, or adaptation of the specific embodiments described or rendering the principles and concept of the present application applicable to any field or art thereof. The specification and examples are to be regarded as exemplary only, and the true scope and spirit of the application is indicated by the following claims.

[0226] It is to be understood that the application is not limited to what has been described above and that modifications and changes can come within the scope thereof without departing from this scope. It is also to be understood that the following claims are to cover all generic and specific features of the application described herein and equivalents thereof and that the description and examples are to be construed as illustrative only and not limiting of the true scope and spirit of the application.

Claims

1. An aqueous emulsion 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, 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 cyclotriphosphazene based epoxy phosphonate fatty acid ester, and (iii) free radical polymerizing the cyclotriphosphazene 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.

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

1.

3. The composition of claim 2, wherein the ratio of the molar amount of the cyclotriphosphazene based epoxy resin to the molar amount of phosphoric acid in step (i) is from 5:1 to 1:1 and is not 1:

1.

4. The composition of claim 3, wherein the ratio of the molar amount of the cyclotriphosphazene based epoxy resin to the molar amount of phosphoric acid in step (i) is from 3.5:1 to 1.1:

1.

5. The composition of claim 1 or 2, wherein n is 1 or 2.

6. The composition of claim 1 or 2, wherein the C3-6 unsaturated fatty acid is selected from one or more of acrylic acid, methacrylic acid, and maleic acid.

7. The composition of claim 6, wherein the C3-6 unsaturated fatty acid is acrylic acid and / or methacrylic acid.

8. The composition of claim 1 or 2, wherein a solvent is added to the system at the end of the esterification reaction of step (ii).

9. The composition of claim 8, wherein the solvent is one or more alcohol ether solvents.

10. The composition of claim 8, wherein the solvent is selected from at least one of propylene glycol butyl ether, n-butanol, ethylene glycol butyl ether, glycerol methyl ether, propylene glycol methyl ether, and isobutyl alcohol.

11. The composition of claim 8, wherein the solvent is selected from propylene glycol methyl ether, ethylene glycol butyl ether, n-butanol, or a mixture of two or more of the foregoing.

12. The composition of claim 8, wherein the solvent is added such that the resulting cyclotriphosphazene based epoxy phosphonate fatty acid ester solution has a solids content of from 55 wt% to 90 wt%.

13. The composition of claim 8, wherein the solvent is added such that the resulting cyclotriphosphazene based epoxy phosphonate fatty acid ester solution has a solids content of from 60 wt% to 80 wt%.

14. The composition of claim 1 or 2, wherein the ethylenically unsaturated monomer in step (iii) is selected from one or more of C1-6 linear or branched alkyl vinyl carboxylate, C6-10 aryl vinyl, C1-12 linear or branched alkyl (meth)acrylate, and (meth)acrylic acid.

15. The composition of claim 14, wherein the ethylenically unsaturated monomer in step (iii) is selected from one or more of vinyl acetate, isooctyl acrylate, vinyl versatate, acrylic acid, styrene, butyl acrylate, methacrylic acid, methyl methacrylate, ethyl acrylate.

16. The composition of claim 1 or 2, wherein the aqueous silica sol has a solids content of 6.5% to 12.5%.

17. The composition of claim 16, wherein the aqueous silica sol has a solids content of 6.5% to 12%.

18. The composition of claim 17, wherein the aqueous silica sol has a solids content of 7% to 12%.

19. The composition of claim 18, wherein the aqueous silica sol has a solids content of 7% to 11.5%.

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

21. The composition of claim 20, wherein the composition comprises 3.5% to 6% silica based on the total weight of the composition.

22. The composition of claim 1 or 2, wherein, the composition comprises 40-50% of component (A) based on the total weight of the composition.

23. The composition of claim 1 or 2, which does not comprise an emulsification aid or a film- forming aid.

24. A method of making an aqueous emulsion composition, comprising: (1) preparing a nitrogen and phosphorus containing modified epoxy resin, comprising: (i) esterifying a cyclotriphosphazene based epoxy resin of Formula I with phosphoric acid to obtain a cyclotriphosphazene based epoxy phosphate ester, I wherein, R1 is -O-Ph-CH2- wherein O is connected 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, 2, 3, 4, 5, or 6; (ii) esterifying the cyclotriphosphazene based epoxy phosphate ester with a C3-6 unsaturated fatty acid or an anhydride thereof to obtain a cyclotriphosphazene based epoxy phosphate fatty acid ester, and (iii) free radical polymerizing the cyclotriphosphazene based epoxy phosphate 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 alkyl ester of an acid, and an ethylenically unsaturated alkenyl ester of an acid; (2) adding an aqueous silica sol to the nitrogen and phosphorus containing modified epoxy resin under agitation, and then continuing to maintain agitation until a uniformly dispersed emulsion is obtained.

25. A modified epoxy resin made by a method comprising: (i) esterifying a cyclotriphosphazene based epoxy resin of Formula I with phosphoric acid to obtain a cyclotriphosphazene based epoxy phosphate ester, I wherein, R1 is -O-Ph-CH2- wherein O is connected 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, 2, 3, 4, 5, or 6; (ii) esterifying the cyclic phosphazene-based epoxy phosphonate with a C3-6 unsaturated fatty acid or an acid anhydride thereof to obtain a cyclic phosphazene-based epoxy phosphonate fatty acid ester, and (iii) subjecting the cyclic phosphazene-based epoxy phosphonate fatty acid ester to a radical polymerization reaction with an ethylenically unsaturated monomer to obtain the 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.

26. Use of the aqueous emulsion composition according to any one of claims 1 to 23 or obtained according to the method of claim 24 for the preparation of a thin aqueous intumescent fireproof coating.

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