Composite flame-retardant coating as well as preparation method and application method thereof

Abstract

The invention provides a composite flame-retardant coating as well as a preparation method and an application method thereof. The composite flame-retardant coating comprises an intumescent flame-retardant coating and a ceramic flame-retardant coating, coating a base material with the intumescent flame-retardant coating, and drying to form an intumescent flame-retardant coating; coating the intumescent flame-retardant coating with a ceramic flame-retardant coating, and drying the intumescent flame-retardant coating to form a ceramic flame-retardant coating; the intumescent flame-retardant coating is foamed and expanded under high-temperature combustion, the ceramic flame-retardant coating on the surface layer is raised, and meanwhile, the ceramic flame-retardant coating is sintered at a higher temperature to realize careful ceramization, so that better fireproof performance is realized; a loose and porous structure in the ceramic flame-retardant coating is beneficial to reduction of heat conduction; the ceramic flame-retardant coating is further heated to quickly react to generate a very compact ceramic structure, flame is directly isolated, erosion of the flame to the expansion layer is avoided, meanwhile, the ceramic flame-retardant coating also has the characteristic of slow heat transfer, and the expansion layer is further coordinated to achieve the aim of protecting the body.

Description

Technical Field

[0001] The invention relates to the technical field of flame retardant coatings, and in particular to a composite flame retardant coating and a preparation method and an application method thereof. Background Art

[0002] In modern society, the frequent occurrence of fire accidents poses a serious threat to the safety of people's lives and property. According to statistics, a large number of fire accidents are caused by the flammability of the materials themselves. Therefore, passive fire protection is a viable option to reduce fire losses or postpone the inevitable fire damage to allow time to save human lives or rescue assets. Among the passive fire protection measures, intumescent flame retardant coatings (IFRCs) are one of the most common and effective forms of protection. It has the advantages of simple production process, keeping the inherent characteristics of the substrate intact, and easy application to various materials. In addition, intumescent coatings can protect steel structures from corrosion during their service life. IFRCs form a thick protective carbonized layer, creating an effective thermal barrier insulation layer between the flame and the substrate.

[0003] Although there are many products of intumescent flame retardant / fireproof coatings, the existing flame retardant coatings still have certain limitations in terms of high temperature resistance. On the one hand, it is difficult for a single-component flame retardant coating to meet the requirements of high temperature resistance and flame retardancy at the same time; on the other hand, the flame retardant effect and stability of existing composite flame retardant coatings at high temperatures still need to be improved. In order to solve this problem, researchers are constantly exploring new coating formulas and preparation processes. As a new type of functional material, high-temperature resistant composite flame retardant coatings have the characteristics of remaining stable and preventing the spread of flames in high temperature environments. The core of its technology lies in constructing a composite system composed of an organic expansion layer and an inorganic ceramic material. The organic expansion layer foams under high temperature to form a loose expansion structure, which plays a role in isolating heat; the inorganic ceramic material can form a dense protective film at high temperature to further isolate the flame and reduce energy transfer.

[0004] However, the existing preparation methods of high-temperature resistant composite flame-retardant coatings have the following problems: First, the compatibility problem. The poor compatibility of different components leads to uneven internal structure of the coating, affecting the performance of the coating. Second, the synergistic fire-retardant performance of multiple components, the mismatch of thermal decomposition temperature of multi-component flame-retardant ingredients, and the durability problem of materials, which causes the flame-retardant process to fail during the fire-proofing process. Third, the porosity or structural damage of the coating. At high temperatures, the surface of the coating may form porous structures or cracks, which directly reduce its thermal insulation and flame-retardant properties. Based on the above problems, the applicability of fire-retardant coatings is limited, especially for materials with high surface treatment requirements.

[0005] Based on the defects of the current high temperature resistant composite flame retardant coatings, it is necessary to improve them. Summary of the invention

[0006] In view of this, the present invention proposes a composite flame retardant coating and a preparation method and an application method thereof to solve or partially solve the problems existing in the prior art.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing a composite flame retardant coating, wherein the composite flame retardant coating comprises an intumescent flame retardant coating and a ceramic flame retardant coating;

[0009] The method for preparing the intumescent flame retardant coating comprises the following steps:

[0010] Phytic acid and dicyandiamide are dissolved in DMF and subjected to solvent thermal reaction to obtain amidine phosphate polymers;

[0011] The amidine phosphate polymer is dissolved in a polyvinyl alcohol aqueous solution, and ammonium polyphosphate is added to carry out a hydrothermal reaction to obtain an intumescent flame retardant coating;

[0012] The preparation method of the ceramic flame retardant coating comprises:

[0013] The boric acid, aluminum oxide and silicon oxide are mixed, ground and calcined to obtain a composite material;

[0014] The composite material is added into the silicone resin to obtain a ceramic flame retardant coating.

[0015] Preferably, in the step of dissolving phytic acid and dicyandiamide in DMF and performing a solvothermal reaction, the temperature of the solvothermal reaction is 100 to 200° C. and the time is 3 to 15 hours.

[0016] Preferably, in the step of dissolving the amidine phosphate polymer into a polyvinyl alcohol aqueous solution, adding ammonium polyphosphate, and conducting a hydrothermal reaction, the hydrothermal reaction temperature is 80 to 150° C. and the time is 2 to 10 hours.

[0017] Preferably, the mass volume ratio of the phytic acid, dicyandiamide, polyvinyl alcohol aqueous solution and DMF is 500g: (150-200)g: (2500-3000)g: (1-1.5)L;

[0018] The mass concentration of the polyvinyl alcohol aqueous solution is 10-15%.

[0019] Preferably, after grinding the boric acid, aluminum oxide and silicon oxide, in the calcination step, the calcination temperature is 300 to 500° C. and the time is 3 to 10 hours.

[0020] Preferably, the boric acid, aluminum oxide and silicon oxide are mixed and ground to a particle size of ≤1 μm;

[0021] And / or, the mass volume ratio of the boric acid, aluminum oxide, silicon oxide and silicone resin is 100g:(300-1200)g:(800-1500)g:(1-1.5)L;

[0022] And / or, the organic silicone resin is an organic silicone resin containing hydroxyl groups or an organic silicone resin containing amino groups.

[0023] In a second aspect, the present invention further provides a composite flame retardant coating, which is prepared by the preparation method.

[0024] In a third aspect, the present invention also provides a composite flame retardant coating prepared by the preparation method or use of the composite flame retardant coating in the preparation of flame retardant products.

[0025] In a fourth aspect, the present invention further provides an application method of the composite flame retardant coating, comprising the following steps:

[0026] Applying the intumescent flame retardant coating to a substrate and drying the coating to form an intumescent flame retardant coating;

[0027] The ceramic flame retardant coating is applied onto the intumescent flame retardant coating and dried to form a ceramic flame retardant coating.

[0028] Preferably, the material of the substrate is any one of steel, wood, and polymer material;

[0029] If the material of the substrate is steel, the thickness ratio of the intumescent flame retardant coating to the ceramic flame retardant coating is (2-5):1;

[0030] If the material of the substrate is wood, the thickness ratio of the intumescent flame retardant coating to the ceramic flame retardant coating is (1-3):2;

[0031] If the material of the substrate is a polymer material, the thickness ratio of the expansion flame retardant coating and the ceramic flame retardant coating is (1-1.5):1.

[0032] The composite flame retardant coating and its preparation method and application method of the present invention have the following beneficial effects compared with the prior art:

[0033] 1. A method for preparing a composite flame-retardant coating of the present invention, wherein the composite flame-retardant coating comprises an intumescent flame-retardant coating and a ceramic flame-retardant coating; wherein, when preparing the intumescent flame-retardant coating, organic phytic acid and dicyandiamide are polymerized at high temperature and high pressure to form a three-dimensional amidine phosphate polymer, and ammonium polyphosphate is coated, and finally the coated component is grafted into a polyvinyl alcohol system; here, polyvinyl alcohol is used as a green binder to bond to the surface of the protected substrate on the one hand, and can also be used as a carbon source (polyol) in the intumescent flame-retardant coating on the other hand; for the preparation of the ceramic flame-retardant coating, boric acid is directly coated on the surface of silicon oxide and aluminum oxide at high temperature, which is to reduce the ceramicization temperature and play the role of a co-solvent; the composite material coated with boric acid is grafted into an organosilicon resin system, which can also achieve stable storage of the coating product and long-term stability and non-migration of the coating after drying; finally, the two coatings are further cross-linked by boric acid and polyvinyl alcohol to achieve a good effect of interface stability and no peeling; therefore, the present invention solves the problems existing in most products on the market, and at the same time, it innovatively combines two excellent fireproof mechanisms, which has high practical significance and application value;

[0034] 2. The present invention applies the intumescent flame retardant coating to the substrate, dries it, and forms an intumescent flame retardant coating; applies the ceramic flame retardant coating to the intumescent flame retardant coating, dries it, and forms a ceramic flame retardant coating; utilizes the intumescent flame retardant coating to foam and expand under high temperature combustion, "raises" the surface ceramic flame retardant coating, and at the same time, the ceramic flame retardant coating is sintered at a higher temperature to achieve careful ceramicization, thereby achieving better fireproof performance; in terms of fireproof performance, the intumescent flame retardant coating preferentially undergoes catalytic carbonization and expansion reaction, and the ceramic flame retardant coating is rapidly "raised", and the loose porous structure in the ceramic flame retardant coating is conducive to reducing heat conduction; further heating the ceramic flame retardant coating will react rapidly to generate a very dense ceramic structure, directly isolate the flame, and avoid its erosion of the intumescent layer, and at the same time, the ceramic flame retardant coating also has the characteristic of slow heat transfer, and further coordinates the intumescent layer to achieve the purpose of protecting the body; wherein, boric acid has many functions in the system, on the one hand, it maintains the stability of the coating, and on the other hand, it reduces the ceramicization temperature and acts as a cosolvent. Therefore, the invention has high practical significance and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0036] Figure 1This is a scanning electron microscope image (SEM) of the organic-coated ammonium polyphosphate prepared in Example 1;

[0037] Figure 2 This is a scanning electron microscope (SEM) image of boric acid adsorbed silicon oxide and aluminum oxide prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0038] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] In the description of the present invention, it should be understood that the directions or positions indicated by “upper” and the like are based on the directions or positions shown in the accompanying drawings, or are the directions or positions in which the product of the invention is usually placed when in use, or are directions or positions commonly understood by those skilled in the art. These directions or positions are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0040] The order of description of the following embodiments is not intended to limit the preferred order of the embodiments. In addition, in the description of the present application, the term "including" means "including but not limited to". Various embodiments of the present invention may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated in this article, it is meant to include any cited numbers (fractions or integers) within the indicated range.

[0041] The embodiment of the present application provides a method for preparing a composite flame retardant coating, wherein the composite flame retardant coating includes an intumescent flame retardant coating and a ceramic flame retardant coating;

[0042] The method for preparing the intumescent flame retardant coating comprises the following steps:

[0043] S11, dissolving phytic acid and dicyandiamide in DMF, and performing a solvothermal reaction to obtain an amidine phosphate polymer;

[0044] S12, dissolving the amidine phosphate polymer into a polyvinyl alcohol aqueous solution, adding ammonium polyphosphate, and performing a hydrothermal reaction to obtain an intumescent flame retardant coating;

[0045] A method for preparing a ceramic flame retardant coating comprises:

[0046] S21, mixing boric acid, aluminum oxide and silicon oxide, grinding and calcining to obtain a composite material;

[0047] S22. Add the composite material into silicone resin to obtain a ceramic flame retardant coating.

[0048] The preparation method of the composite flame retardant coating of the present invention aims to solve the problems of poor temperature resistance, poor coating stability and low coordinated flame retardant efficiency of traditional intumescent fire retardant coatings; specifically, the composite flame retardant coating comprises an intumescent flame retardant coating and a ceramic flame retardant coating, wherein, when preparing the intumescent flame retardant coating, organic phytic acid (chemical formula C6H 18 O 24 P6) and dicyandiamide (chemical formula C2H4N4) undergo polymerization reaction at high temperature and high pressure to form a three-dimensional amidine phosphate polymer, and ammonium polyphosphate is coated, and finally the coated component is grafted into the polyvinyl alcohol system; here, polyvinyl alcohol is used as a green binder on the one hand, bonded to the surface of the protected substrate, and on the other hand, it can also be used as a carbon source (polyol) in the intumescent flame retardant coating; for the preparation of ceramic flame retardant coatings, boric acid is directly coated on the surface of silicon oxide and aluminum oxide at high temperature, which is to reduce the ceramicization temperature and play the role of a co-solvent; the composite material coated with boric acid is then grafted into the silicone resin system, which can also achieve stable storage of the coating product and long-term stability and non-migration of the coating after drying; finally, the two coatings are further cross-linked by boric acid and polyvinyl alcohol to achieve a good effect of interface stability and no peeling. Therefore, this invention solves the problems of most products on the market, and at the same time, it innovatively combines two excellent fire protection mechanisms, which has high practical significance and application value.

[0049] In some embodiments, in the step of dissolving phytic acid and dicyandiamide in DMF (N,N-dimethylformamide) and performing a solvothermal reaction, the temperature of the solvothermal reaction is 100-200° C. and the time is 3-15 hours.

[0050] Specifically, phytic acid and dicyandiamide are dissolved in DMF, a solvent thermal reaction is carried out, the product is cooled and distilled at low pressure to separate DMF and the amidine phosphate polymer, and the amidine phosphate polymer is obtained.

[0051] In some embodiments, in the step of dissolving the amidine phosphate polymer into a polyvinyl alcohol aqueous solution, adding ammonium polyphosphate, and conducting a hydrothermal reaction, the hydrothermal reaction temperature is 80-150° C. and the time is 2-10 hours.

[0052] Specifically, the amidine phosphate polymer is dispersed in a polyvinyl alcohol aqueous solution, heated to dissolve it, and then ammonium polyphosphate is added to further react at high temperature and high pressure through hydrothermal reaction to form a uniform dispersion to obtain an intumescent flame retardant coating.

[0053] In some embodiments, the mass volume ratio of phytic acid, dicyandiamide, polyvinyl alcohol aqueous solution and DMF is 500 g: (150-200) g: (2500-3000) g: (1-1.5) L;

[0054] The mass concentration of the polyvinyl alcohol aqueous solution is 10-15%.

[0055] In some embodiments, after grinding the boric acid, aluminum oxide and silicon oxide, in the step of calcining, the calcination temperature is 300-500° C. and the time is 3-10 hours.

[0056] Specifically, boric acid, aluminum oxide and silicon oxide are dispersed and ground in a sand mill, and then subjected to high-temperature calcination to form a boric acid-coated aluminum oxide and silicon oxide composite material; the composite material is crushed, added to an organic silicon resin, and stirred until uniformly dispersed to obtain a ceramic flame retardant coating.

[0057] In some embodiments, boric acid, aluminum oxide, and silicon oxide are mixed and ground to a particle size of ≤1 μm.

[0058] In some embodiments, the mass volume ratio of boric acid, aluminum oxide, silicon oxide and silicone resin is 100 g: (300-1200) g: (800-1500) g: (1-1.5) L.

[0059] In some embodiments, the silicone resin is a hydroxyl-containing silicone resin or an amino-containing silicone resin.

[0060] In some embodiments, boric acid, aluminum oxide and silicon oxide are dispersed in water, and cyclically ground by a high-speed sand mill until the final particle size is ≤1 μm to obtain a mixture, and the mixture is dried and then calcined at high temperature to form a boric acid-coated aluminum oxide and silicon oxide composite material; wherein the mass ratio of boric acid to water is 1:(1-2).

[0061] Based on the same inventive concept, the present invention also provides a composite flame retardant coating, which is prepared by the above-mentioned preparation method.

[0062] Based on the same inventive concept, the present invention also provides a composite flame retardant coating prepared by the above-mentioned preparation method or the use of the above-mentioned composite flame retardant coating in the preparation of flame retardant products.

[0063] Based on the same inventive concept, the present invention also provides an application method of the above-mentioned composite flame retardant coating, comprising the following steps:

[0064] applying an intumescent flame retardant coating onto a substrate and drying the coating to form an intumescent flame retardant coating;

[0065] The ceramic flame retardant coating is applied onto the intumescent flame retardant coating and dried to form the ceramic flame retardant coating.

[0066] Specifically, in the above embodiment, the ceramic flame retardant coating is coated on the intumescent flame retardant coating. During drying, the boric acid in the ceramic flame retardant coating and the polyvinyl alcohol in the intumescent flame retardant coating will further undergo a cross-linking reaction.

[0067] In some embodiments, the material of the substrate is any one of steel, wood, and polymer materials;

[0068] If the material of the substrate is steel, the thickness ratio of the intumescent flame retardant coating and the ceramic flame retardant coating is (2-5):1;

[0069] If the material of the substrate is wood, the thickness ratio of the intumescent flame retardant coating and the ceramic flame retardant coating is (1-3):2;

[0070] If the material of the substrate is a polymer material, the thickness ratio of the expansion flame retardant coating and the ceramic flame retardant coating is (1-1.5):1.

[0071] The present invention applies an intumescent flame retardant coating to a substrate, dries it, and forms an intumescent flame retardant coating; applies a ceramic flame retardant coating to the intumescent flame retardant coating, dries it, and forms a ceramic flame retardant coating; utilizes the intumescent flame retardant coating to foam and expand under high-temperature combustion to "lift" the surface ceramic flame retardant coating, and at the same time, the ceramic flame retardant coating is sintered at a higher temperature to achieve thorough ceramicization, thereby achieving better fireproofing performance.

[0072] The composite flame retardant coating prepared by the present invention is coated on a substrate to form an intumescent flame retardant coating and a ceramic flame retardant coating. The coating can not only combine the advantages of the intumescent coating to isolate the transfer of flame and energy, but also has the ability of thermal insulation and flame penetration isolation of the ceramic flame retardant coating, achieving the goal of 1+1>2. The specific principle is to coat the ammonium polyphosphate through the cross-linking reaction of phytic acid and dicyandiamide, thereby solving the problems of uneven dispersion and easy migration of inorganic flame retardants in the later stage; at the same time, the grafting reaction of excess phosphate with polyvinyl alcohol can reduce the acidity of the system and corrode the protected body; on the other hand, the organic coated ammonium polyphosphate can also be firmly confined in the system by polyvinyl alcohol, fundamentally solving the problems of dispersion and stability of inorganic flame retardants in organic systems. In addition, boric acid can be adsorbed onto the surface of alumina and silica at high temperature, and then dispersed into the silicone resin. Boric acid undergoes a cross-linking reaction with the hydroxyl or amino group in the silicone. The benefit is that the viscosity of the system is increased and the stability of the liquid system is improved. At the same time, after the coating is dried, the outer surface hardness and strength are high, and the inner expansion layer can be protected from damage. Finally, the expansion flame retardant coating and the ceramic flame retardant coating are still combined by chemical bonding, that is, boric acid and polyvinyl alcohol can undergo a cross-linking polymerization reaction, making the two coatings more tightly and stably combined.

[0073] In terms of fireproof performance, the intumescent flame retardant coating preferentially undergoes catalytic carbonization and expansion reaction, which rapidly "raises" the ceramic flame retardant coating. The loose and porous structure in the ceramic flame retardant coating is conducive to reducing heat conduction. Further heating of the ceramic flame retardant coating will rapidly react to generate a very dense ceramic structure, directly isolating the flame and preventing it from corroding the expansion layer. At the same time, the ceramic flame retardant coating also has the characteristic of slow heat transfer, which further coordinates the expansion layer to achieve the purpose of protecting the body. Among them, boric acid plays many roles in this system. On the one hand, it maintains the stability of the coating, and on the other hand, it reduces the ceramicization temperature and acts as a co-solvent. Therefore, the invention has high practical significance and application value.

[0074] The composite fire-retardant coating formed by the composite flame-retardant coating prepared by the present invention, compared with the traditional expansion coating, on the one hand improves the uniform dispersion and stability of the flame-retardant component in the binder system; on the other hand, the thermal decomposition and synergistic effect between different fire-retardant components are reasonably designed, so that the outer surface is a layer of solid ceramic oxide to isolate the erosion of flames, and the interior is a loose expansion structure to delay heat transfer, thereby achieving a high-efficiency fire protection purpose.

[0075] The following further illustrates the composite flame retardant coating of the present application and its preparation method and application method with specific examples. This section further illustrates the content of the present invention in conjunction with specific examples, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0076] The organic silicon resin used in the following examples is an organic silicon resin containing hydroxyl groups, and the specific model is Dow Corning RSN 6018 organic silicon resin.

[0077] The embodiment of the present application provides a method for preparing a composite flame retardant coating, wherein the composite flame retardant coating includes an intumescent flame retardant coating and a ceramic flame retardant coating;

[0078] The method for preparing the intumescent flame retardant coating comprises the following steps:

[0079] S11, dissolving 500 g of phytic acid and 150 g of dicyandiamide in 1 L of N,N-dimethylformamide (DMF), carrying out polymerization reaction at 180° C. for 5 h, cooling the material and performing low-pressure distillation to separate DMF and the amidino phosphate polymer, and obtaining the amidino phosphate polymer;

[0080] S12, dispersing the amidine phosphate polymer in S11 into 3000g of polyvinyl alcohol aqueous solution (polyvinyl alcohol aqueous solution mass concentration is 10%), heating to 80°C to dissolve the amidine phosphate polymer, adding 2000g of ammonium polyphosphate, heating to 120°C again, and reacting at 120°C for 3h, and finally cooling to room temperature (25°C) to form a uniform dispersion to obtain an intumescent flame retardant coating;

[0081] A method for preparing a ceramic flame retardant coating comprises:

[0082] S21, dispersing 100 g of boric acid, 500 g of aluminum oxide, and 1500 g of silicon oxide into 100 mL of water, and grinding the mixture in a high-speed sand mill until the particle size of each material is ≤500 nm, to obtain a mixture;

[0083] The mixture was dried at 100 °C for 12 h;

[0084] The dried mixture was calcined at 350°C for 5 h to obtain a boric acid-coated alumina and silicon oxide composite material;

[0085] S22. The composite material in S21 is crushed and added into 1 L of silicone resin, and stirred until uniformly dispersed to obtain a ceramic flame retardant coating; the silicone resin is a silicone resin containing hydroxyl groups, and the specific model is Dow Corning RSN 6018 silicone resin.

[0086] This embodiment also provides an application method of the composite flame retardant coating, comprising the following steps:

[0087] S31, coating the intumescent flame retardant coating prepared in Example 1 on the surface of wood (thickness 5 mm), and drying at room temperature (25° C.) for 24 h to obtain an intumescent flame retardant coating with a thickness of 2 mm;

[0088] S32. Apply the ceramic flame retardant coating prepared in Example 1 onto the intumescent flame retardant coating, and dry at room temperature (25° C.) for 24 hours to obtain a ceramic flame retardant coating with a thickness of 2 mm.

[0089] Example 2

[0090] The embodiment of the present application provides a method for preparing a composite flame retardant coating, wherein the composite flame retardant coating includes an intumescent flame retardant coating and a ceramic flame retardant coating;

[0091] The method for preparing the intumescent flame retardant coating comprises the following steps:

[0092] S11, dissolving 500 g of phytic acid and 150 g of dicyandiamide in 1 L of N,N-dimethylformamide (DMF), carrying out polymerization reaction at 180° C. for 5 h, cooling the material and performing low-pressure distillation to separate DMF and the amidino phosphate polymer, and obtaining the amidino phosphate polymer;

[0093] S12, dispersing the amidine phosphate polymer in S11 into 3000g of polyvinyl alcohol aqueous solution (polyvinyl alcohol aqueous solution mass concentration is 10%), heating to 80°C to dissolve the amidine phosphate polymer, adding 2000g of ammonium polyphosphate, heating to 120°C again, and reacting at 120°C for 3h, and finally cooling to room temperature (25°C) to form a uniform dispersion to obtain an intumescent flame retardant coating;

[0094] A method for preparing a ceramic flame retardant coating comprises:

[0095] S21, dispersing 100 g of boric acid, 1000 g of aluminum oxide, and 1000 g of silicon oxide into 100 mL of water, and grinding the mixture in a high-speed sand mill until the particle size of each material is ≤500 nm, to obtain a mixture;

[0096] The mixture was dried at 100 °C for 12 h;

[0097] The dried mixture was calcined at 400°C for 5h to obtain a boric acid-coated alumina and silicon oxide composite material;

[0098] S22. The composite material in S21 is crushed and added into 1 L of silicone resin, and stirred until uniformly dispersed to obtain a ceramic flame retardant coating; the silicone resin is a silicone resin containing hydroxyl groups, and the specific model is Dow Corning RSN 6018 silicone resin.

[0099] This embodiment also provides an application method of the composite flame retardant coating, comprising the following steps:

[0100] S31, coating the intumescent flame retardant coating prepared in Example 2 on the surface of a steel material (thickness 5 mm), and drying at room temperature (25° C.) for 24 h to obtain an intumescent flame retardant coating with a thickness of 3 mm;

[0101] S32. Apply the ceramic flame retardant coating prepared in Example 2 onto the intumescent flame retardant coating, and dry at room temperature (25° C.) for 24 hours to obtain a ceramic flame retardant coating with a thickness of 1 mm.

[0102] Example 3

[0103] The embodiment of the present application provides a method for preparing a composite flame retardant coating, wherein the composite flame retardant coating includes an intumescent flame retardant coating and a ceramic flame retardant coating;

[0104] The method for preparing the intumescent flame retardant coating comprises the following steps:

[0105] S11, dissolving 500 g of phytic acid and 200 g of dicyandiamide in 1 L of N,N-dimethylformamide (DMF), carrying out polymerization reaction at 150° C. for 5 h, cooling the material and performing low-pressure distillation to separate DMF and the amidino phosphate polymer, and obtaining the amidino phosphate polymer;

[0106] S12, dispersing the amidine phosphate polymer in S11 into 2500g of polyvinyl alcohol aqueous solution (polyvinyl alcohol aqueous solution mass concentration is 10%), heating to 80°C to dissolve the amidine phosphate polymer, adding 1500g of ammonium polyphosphate, heating to 120°C again, and reacting at 120°C for 3h, and finally cooling to room temperature (25°C) to form a uniform dispersion to obtain an intumescent flame retardant coating;

[0107] A method for preparing a ceramic flame retardant coating comprises:

[0108] S21, dispersing 100 g of boric acid, 300 g of aluminum oxide, and 1000 g of silicon oxide into 100 mL of water, and grinding the mixture in a high-speed sand mill until the particle size of each material is ≤500 nm, to obtain a mixture;

[0109] The mixture was dried at 100 °C for 12 h;

[0110] The dried mixture was calcined at 400°C for 5h to obtain a boric acid-coated alumina and silicon oxide composite material;

[0111] S22. The composite material in S21 is crushed and added into 1 L of silicone resin, and stirred until uniformly dispersed to obtain a ceramic flame retardant coating; the silicone resin is a silicone resin containing hydroxyl groups, and the specific model is Dow Corning RSN 6018 silicone resin.

[0112] This embodiment also provides an application method of the composite flame retardant coating, comprising the following steps:

[0113] S31, coating the intumescent flame retardant coating prepared in Example 3 on the surface of a polymer (specifically a PP (polypropylene) substrate with a thickness of 5 mm), and drying at room temperature (25° C.) for 24 h to obtain an intumescent flame retardant coating with a thickness of 2 mm;

[0114] S32. Apply the ceramic flame retardant coating prepared in Example 3 onto the intumescent flame retardant coating, and dry at room temperature (25° C.) for 24 hours to obtain a ceramic flame retardant coating with a thickness of 2 mm.

[0115] Comparative Example 1

[0116] This comparative example provides a method for preparing an intumescent flame retardant coating, comprising the following steps:

[0117] S11, dissolving 500 g of phytic acid and 150 g of dicyandiamide in 1 L of N,N-dimethylformamide (DMF), carrying out polymerization reaction at 180° C. for 5 h, cooling the material and performing low-pressure distillation to separate DMF and the amidino phosphate polymer, and obtaining the amidino phosphate polymer;

[0118] S12, dispersing the amidine phosphate polymer in S11 into 3000g of polyvinyl alcohol aqueous solution (polyvinyl alcohol aqueous solution mass concentration is 10%), heating to 80°C to dissolve the amidine phosphate polymer, adding 2000g of ammonium polyphosphate, heating to 120°C again, and reacting at 120°C for 3h, and finally cooling to room temperature (25°C) to form a uniform dispersion to obtain an intumescent flame retardant coating;

[0119] This comparative example also provides an application method of the above-mentioned intumescent flame retardant coating, comprising the following steps:

[0120] The intumescent flame retardant coating prepared in Comparative Example 1 was coated on the surface of a steel material (5 mm thick) and dried at room temperature (25° C.) for 24 h to obtain an intumescent flame retardant coating with a thickness of 4 mm.

[0121] Comparative Example 2

[0122] This comparative example provides a method for preparing a ceramic flame retardant coating, comprising the following steps:

[0123] S11, dispersing 100 g of boric acid, 1000 g of aluminum oxide, and 1000 g of silicon oxide into 100 mL of water, and grinding the mixture in a high-speed sand mill until the particle size of each material is ≤500 nm, to obtain a mixture;

[0124] The mixture was dried at 100 °C for 12 h;

[0125] The dried mixture was calcined at 400°C for 5h to obtain a boric acid-coated alumina and silicon oxide composite material;

[0126] S12, crushing the composite material in S11 and adding it into 1L of silicone resin, stirring until it is evenly dispersed, to obtain a ceramic flame retardant coating; the silicone resin is a silicone resin containing hydroxyl groups, and the specific model is Dow Corning RSN 6018 silicone resin.

[0127] This comparative example also provides an application method of the ceramic flame retardant coating, comprising the following steps:

[0128] The ceramic flame retardant coating prepared in Comparative Example 2 was applied to the surface of a steel material (5 mm thick) and dried at room temperature (25° C.) for 24 hours to obtain a ceramic flame retardant coating with a thickness of 4 mm.

[0129] Performance Testing

[0130] Figure 1 This is a scanning electron microscope image (SEM) of the organic-coated ammonium polyphosphate prepared in Example 1.

[0131] from Figure 1 It can be seen that the size of the organic-coated ammonium polyphosphate is 300-500nm and is very evenly distributed.

[0132] Figure 2 This is a scanning electron microscope (SEM) image of boric acid adsorbed silicon oxide and aluminum oxide prepared in Example 1 of the present invention.

[0133] from Figure 2 It can be seen that the boric acid coating and the particle size distribution of silicon oxide and aluminum oxide are uniform, and the surface is very smooth. The fire-retardant coating formed by this has a flat surface and can quickly form a ceramic fire-retardant layer under high-temperature combustion.

[0134] The different substrates prepared in Test Examples 1 to 3 were coated with the composite flame retardant coating to form a coating, which was tested in a propane flame for 10 minutes. The intumescent flame retardant coating and the ceramic flame retardant coating formed in Comparative Examples 1 to 2 were used as comparisons and the test results were tested in a propane flame for 10 minutes. Pure steel, pure wood, and pure PP (polypropylene) with a thickness of 5 mm were used as substrates without coating with flame retardant coating (i.e., the coating thickness was 0 mm) and tested in a propane flame for 10 minutes. The test results are shown in Table 1 below.

[0135] Table 1 - Fire resistance test of coatings formed after applying composite flame retardant coatings in different embodiments

[0136]

[0137]

[0138] The total coating thickness in Table 1 refers to the sum of the thicknesses of all coatings on the substrate; the total coating thickness after expansion refers to the total thickness of the coating after the coating expands during the coating test; the back surface temperature of the substrate refers to the end surface temperature of the substrate without coating.

[0139] It can be seen from Table 1 that the composite flame retardant coating prepared by the present invention has excellent fire retardant performance, and can be applied to steel, wood and plastic products, and exhibits excellent fire resistance during the fire resistance test.

[0140] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a composite flame retardant coating, characterized in that: The composite flame retardant coating comprises an intumescent flame retardant coating and a ceramic flame retardant coating; The method for preparing the intumescent flame retardant coating comprises the following steps: Phytic acid and dicyandiamide are dissolved in DMF and subjected to solvent thermal reaction to obtain amidine phosphate polymers; The amidine phosphate polymer is dissolved in a polyvinyl alcohol aqueous solution, and ammonium polyphosphate is added to carry out a hydrothermal reaction to obtain an intumescent flame retardant coating; The preparation method of the ceramic flame retardant coating comprises: The boric acid, aluminum oxide and silicon oxide are mixed, ground and calcined to obtain a composite material; The composite material is added into the silicone resin to obtain a ceramic flame retardant coating.

2. The method for preparing the composite flame retardant coating according to claim 1, characterized in that: In the step of dissolving phytic acid and dicyandiamide in DMF and performing a solvothermal reaction, the temperature of the solvothermal reaction is 100 to 200° C. and the time is 3 to 15 hours.

3. The method for preparing the composite flame retardant coating according to claim 1, characterized in that: In the step of dissolving the amidine phosphate polymer into a polyvinyl alcohol aqueous solution, adding ammonium polyphosphate, and performing a hydrothermal reaction, the hydrothermal reaction temperature is 80 to 150° C. and the time is 2 to 10 hours.

4. The method for preparing the composite flame retardant coating according to claim 1, characterized in that: The mass volume ratio of the phytic acid, dicyandiamide, polyvinyl alcohol aqueous solution and DMF is 500g: (150-200)g: (2500-3000)g: (1-1.5)L; The mass concentration of the polyvinyl alcohol aqueous solution is 10-15%.

5. The method for preparing the composite flame retardant coating according to claim 1, characterized in that: After grinding the boric acid, aluminum oxide and silicon oxide, in the calcination step, the calcination temperature is 300-500° C. and the time is 3-10 hours.

6. The method for preparing the composite flame retardant coating according to claim 1, characterized in that: Boric acid, aluminum oxide and silicon oxide are mixed and ground to a particle size of ≤1 μm; And / or, the mass volume ratio of the boric acid, aluminum oxide, silicon oxide and silicone resin is 100g:(300-1200)g:(800-1500)g:(1-1.5)L; And / or, the organic silicone resin is an organic silicone resin containing hydroxyl groups or an organic silicone resin containing amino groups.

7. A composite flame retardant coating, characterized in that: The preparation is obtained by the preparation method according to any one of claims 1 to 6.

8. Use of the composite flame retardant coating prepared by the preparation method according to any one of claims 1 to 6 or the composite flame retardant coating according to claim 7 in the preparation of flame retardant products.

9. An application method of the composite flame retardant coating according to claim 7, characterized in that: The following steps are involved: Applying the intumescent flame retardant coating to a substrate and drying the coating to form an intumescent flame retardant coating; The ceramic flame retardant coating is applied onto the intumescent flame retardant coating and dried to form a ceramic flame retardant coating.

10. The application method according to claim 9, characterized in that: The material of the substrate is any one of steel, wood, and polymer materials; If the material of the substrate is steel, the thickness ratio of the intumescent flame retardant coating to the ceramic flame retardant coating is (2-5):1; If the material of the substrate is wood, the thickness ratio of the intumescent flame retardant coating to the ceramic flame retardant coating is (1-3):2; If the material of the substrate is a polymer material, the thickness ratio of the expansion flame retardant coating and the ceramic flame retardant coating is (1-1.5):1.

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