Preparation Method of Intrinsic Fireproof Waterborne Coating

Abstract

The present invention provides a preparation method of an intrinsic fireproof waterborne coating, which relates to a fireproof coating. It includes preparing a polyvinyl chloride seed emulsion, an emulsifier, a swelling monomer, etc., and performing swelling polymerization according to steps to obtain a swollen polymer; then preparing deionized water, a phosphorus-containing emulsifier, butyl acrylate, methyl methacrylate, etc., and performing emulsion polymerization to obtain an emulsion; afterwards, preparing a dispersant, a wetting agent, an antifoaming agent, cellulose, etc. by weight parts and preparing according to the preparation steps to obtain the intrinsic fireproof waterborne coating; the fireproof coating provided by the present invention has intrinsic fireproof performance and can effectively reduce the dosage of flame retardants.

Description

Technical Field

[0001] The present invention relates to a fireproof material, and particularly to a preparation method of an intrinsic fireproof waterborne coating. Background Art

[0002] Fireproof coatings are applied by brushing the coatings on the surface of materials to improve the fire resistance of the materials, slow down the spread speed of the flame, or prevent combustion within a certain period of time. Such coatings are called fireproof coatings or flame retardant coatings.

[0003] For example, CN112409543A discloses a preparation method of a copolymer emulsion of vinyl chloride and acrylate. The obtained emulsion has certain flame retardant properties, self-extinguishing properties and anti-corrosion properties. In this preparation method, a two-step method is adopted, and a copolymer emulsion is prepared with polyvinyl chloride as the "core" structure and polyacrylate as the "shell" structure. Vinyl chloride and acrylate monomers with large differences in reactivity ratios are combined to prepare a composite material. However, in the above method, the obtained "shell" structure is only simply physically coated on the "core" structure, and the stability of the "core-shell" structure is insufficient. Due to the different film-forming rates of the "core" and the "shell", internal stress will be generated during the film-forming process, which will affect the comprehensive performance of the emulsion.

[0004] Therefore, there is an urgent need to provide a fireproof coating to solve the aforementioned technical problems. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention provides a preparation method of an intrinsic fireproof waterborne coating, which solves the technical problem that in the prior art, due to the different film-forming rates of the "core" and the "shell", internal stress is generated during the film-forming process, which affects the comprehensive performance of the emulsion.

[0006] To achieve the above object, the present invention is realized through the following technical solutions:

[0007] The present invention provides a preparation method of an intrinsic fireproof waterborne coating, and the preparation method includes:

[0008] Step 1, swelling polymerization

[0009] 1600 parts by weight of a polyvinyl chloride seed emulsion, 5-8 parts by weight of an emulsifier and 60-80 parts by weight of a swelling monomer are added to a polymerization kettle at one time under stirring, and the temperature of the polymerization kettle is raised to 60-65°C and kept warm for 8-10 h, with continuous stirring during this period at a speed of 3-5 rpm;

[0010] 10-20 parts by weight of a crosslinking monomer are added, stirred for 10-15 min, and the temperature is raised to 80-85°C at a speed of 3-5 rpm;

[0011] The stirring speed is increased to 10 - 15 rpm, 0.1 part by weight of sodium sulfate and 0.1 part by weight of sodium bisulfate are added, and a polymerization reaction is carried out. The pressure is maintained at atmospheric pressure, heat preservation is carried out and continuous stirring is carried out for 30 min, and then it is cooled to room temperature for standby to obtain a swollen polymer;

[0012] Step Two: Emulsion Polymerization

[0013] 160 parts by weight of deionized water are added to a pre-emulsification tank. During stirring, first 15 - 20 parts by weight of an emulsifier and 22 - 25 parts by weight of a phosphorus-containing emulsifier are added, and then 190 - 220 parts by weight of butyl acrylate, 150 parts by weight of methyl methacrylate, 80 parts by weight of acrylic acid, and 105 - 110 parts by weight of methacryloyloxyethyl phosphate are added. After stirring evenly, it is used as a pre-emulsion for standby;

[0014] 40 parts by weight of deionized water are added to a polymerization kettle. During stirring, 1600 parts by weight of the swollen polymer are added, the temperature is raised to 60 ± 1 °C, the pressure is maintained at atmospheric pressure, 0.5 - 0.6 part by weight of sodium persulfate and 0.5 - 0.6 part by weight of sodium bisulfite are added. After stirring evenly, the pre-emulsion is continuously added dropwise, and the dropping rate is controlled to be completed within 1.8 h - 2 h; among them, when the dropping reaches 1.5 h, 12 parts by weight of zinc hydroxy stannate are started to be added dropwise, and it is controlled to be added dropwise within 0.5 h;

[0015] Heat preservation is carried out for 1 h, 0.4 part by weight of vitamin C and 0.8 part by weight of tert-butyl hydroperoxide are added, stirred for 30 min, degassed, cooled to 35 °C, the pH is adjusted to about 8 with ammonia water, and a bactericide is added and stirred evenly to obtain an emulsion;

[0016] Step Three: Coating Preparation

[0017] 30 parts by weight of water are added to a container, the rotation speed is adjusted to 1000 rpm, and 0.5 part by weight of dispersant 5040, 0.3 part by weight of wetting agent, 0.2 part by weight of mineral oil defoamer, and 1 part by weight of lauryl acetate are added in sequence and stirred evenly;

[0018] The rotation speed is adjusted to 1500 rpm, 0.2 part by weight of cellulose is added, and stirred until completely dispersed;

[0019] Keep the rotation speed at 1500 rpm, and 5 parts by weight of rutile titanium dioxide, 10 parts by weight of calcined kaolin, and 22 - 30 parts by weight of heavy calcium are added in sequence and stirred and dispersed for 30 min;

[0020] The rotation speed is reduced to 1000 rpm, 10 parts by weight of expanded vermiculite, 0 - 8 parts by weight of ammonium polyphosphate, and 2 parts by weight of multifunctional amine auxiliary agent are added and stirred evenly;

[0021] Reduce the rotational speed to 500 - 700 rpm, add 20 parts by weight of the said emulsion, 0.2 parts by weight of a bactericide, 0.1 parts by weight of an antifoaming agent and 1 part by weight of ethylene glycol. After stirring evenly, add a polyurethane thickener and an acrylic thickener to make the viscosity about 8000 cp, continue stirring for 10 min, filter and discharge to obtain the said intrinsic fireproof waterborne coating.

[0022] Furthermore, the parameters of the polyvinyl chloride seed emulsion are: solid content 30 - 35%, pH 9 - 11, median particle size 70 - 100 nm.

[0023] Furthermore, the emulsifier is an aqueous solution of sodium dodecylbenzenesulfonate with a solid content of 20%.

[0024] Furthermore, the swelling monomer is butyl acrylate.

[0025] Furthermore, the crosslinking monomer is vinyltrimethoxysilane.

[0026] Furthermore, the phosphorus-containing emulsifier is Solvay RS610.

[0027] Furthermore, the initiator is a redox system low-temperature initiator sodium persulfate and sodium bisulfite.

[0028] Furthermore, the addition amount of ammonium polyphosphate is zero.

[0029] A preparation method of an intrinsic fireproof waterborne coating provided by the present invention has the following beneficial effects compared with the prior art:

[0030] 1. The fireproof coating obtained by the present invention can effectively reduce the dosage and types of flame retardants;

[0031] 2. Without adding flame retardants, the obtained coating still has a flame retardant effect, realizing intrinsic fireproofing;

[0032] 3. Through swelling polymerization, the interfacial force between the polyvinyl chloride seed emulsion and the surface ester polymer is enhanced, and the film-forming performance is improved;

[0033] 4. Through redox system low-temperature initiation polymerization (polymerization temperature 60 ± 1 °C), the stability of the polymerization reaction process is improved, the batch stability of the material is ensured, the obtained product has good repeatability, and the energy consumption is reduced;

[0034] 5. Although the fireproof coating provided by the present invention also belongs to the "core-shell structure", it is not a simple physical coating of the core and the shell. Instead, a crosslinking monomer, vinyltrimethoxysilane, is added between the core-shell interfaces to form an interpenetrating crosslinking network between the core and the shell, increasing the interaction force between the core and the shell and reducing the internal stress caused by the different film-forming rates between the core and the shell during the film-forming process (a large internal stress will cause small cracks to appear in the film during the film-forming process and make it opaque, and the mechanical properties of the film will decrease significantly). As a result, the film becomes a uniform and transparent film. With good film-forming performance, comprehensive properties such as the transparency, tensile strength, elongation at break, and water resistance of the film will be significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0036] Figure 1 It is the electron microscopy scan of the emulsion obtained corresponding to the implementation serial number 6 in Example 2;

[0037] Figure 2 It is the picture of the film formed from the emulsion obtained corresponding to the implementation serial number 6 in Example 2;

[0038] Figure 3 It is the test plate picture of the three products prepared according to the components corresponding to the implementation serial number 5 in Example 3;

[0039] Figure 4 It is the combustion result picture of the three products prepared according to the components corresponding to the implementation serial number 5 in Example 3;

[0040] Figure 5 It is the fireproof principle diagram of the fireproof coating obtained in this application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0042] In the prior art, emulsion-type waterborne intumescent fireproof coatings use water as the dispersion medium, synthetic polymer emulsions as film-forming substances, and are mixed with flame retardants, swelling agents, pigments and fillers, etc. At present, in some emulsion-type waterborne fireproof coatings on the market, the film-forming substance - the polymer emulsion itself not only does not have fireproof performance, but is also a flammable substance. Therefore, a large amount of flame retardant additives need to be added to achieve fireproof performance, and at the same time, the water-based environmental protection of the coating needs to be ensured.

[0043] Since the stability of the polymer emulsion in the fireproof coating system (such as mechanical stability, storage stability, freeze-thaw stability, etc.) is related to the fillers and additives added, in order not to destroy the charge balance on the surface of the emulsion particles and cause demulsification, the fillers in the fireproof coating, especially those that are easy to dissociate into anions and cations in water, should be added as little as possible or not added at all. In addition, adding fillers such as flame retardants also affects the comprehensive performance of the coating, such as the compactness, water resistance, crack resistance, etc. of the coating.

[0044] That is to say, the core substrate - the emulsion used in most emulsion-type fireproof coatings on the market at present not only does not have fireproof performance, but is itself a flammable substance. This is a fatal weakness of some waterborne fireproof coatings. In order to make the flammable substance fireproof, a large amount of additional flame retardant additives need to be added to achieve the fireproof performance of the fireproof coating. On the one hand, the additives increase the cost, and on the other hand, adding too many additives also affects the film-forming performance of the fireproof coating (as described above).

[0045] Therefore, there is an urgent need for an emulsion with certain fireproof performance itself to be used as the film-forming substance (i.e., the core substrate) of the fireproof coating, so that the addition of flame retardant additives can be minimized or preferably not added at all. In this way, both cost can be saved and the film-forming of the emulsion is not affected (because only when the emulsion forms a film smoothly can it adhere to the material and play a fireproof role. If the film-forming process of the emulsion is not smooth, it is very easy to fall off when coated on the material, thus losing the fireproof significance for the material).

[0046] Although "core" and "shell" composite flame retardant materials are disclosed in the prior art, there are differences in the film-forming rates of the "core" and "shell", resulting in internal stress during the film-forming process. In this application, by adding a cross-linking monomer vinyltrimethoxysilane between the core-shell interfaces, an interpenetrating cross-linked network is formed between the core and the shell, increasing the interaction force between the core and the shell, and ensuring that the film-forming rates of the core-shell structures are consistent.

[0047] Specifically, the present invention provides a preparation method of an intrinsic fireproof waterborne coating, and the preparation method includes:

[0048] Step 1, swelling polymerization

[0049] 1600 parts by weight of polyvinyl chloride seed emulsion, 5 - 8 parts by weight of emulsifier, and 60 - 80 parts by weight of swelling monomer are added into the polymerization kettle at one time under stirring, and the temperature of the polymerization kettle is raised to 60 - 65 °C, kept warm for 8 - 10 h, with continuous stirring during this period, and the speed is 3 - 5 rpm;

[0050] 10 - 20 parts by weight of crosslinking monomer are added, stirred for 10 - 15 min, and the temperature is raised to 80 - 85 °C, with a speed of 3 - 5 rpm;

[0051] The stirring speed is increased to 10 - 15 rpm, 0.1 part by weight of sodium sulfate and 0.1 part by weight of sodium bisulfate are added, and polymerization reaction is carried out. The pressure is kept at atmospheric pressure, kept warm and continuously stirred for 30 min, and then cooled to room temperature for standby to obtain the swollen polymer;

[0052] Step Two: Emulsion Polymerization

[0053] 160 parts by weight of deionized water are added into the pre - emulsification tank. During stirring, first 15 - 20 parts by weight of emulsifier and 22 - 25 parts by weight of phosphorus - containing emulsifier are added, and then 190 - 220 parts by weight of butyl acrylate, 150 parts by weight of methyl methacrylate, 80 parts by weight of acrylic acid, and 105 - 110 parts by weight of methacryloyloxyethyl phosphate are added, and stirred evenly to obtain the pre - emulsion for standby;

[0054] 40 parts by weight of deionized water are added into the polymerization kettle. During stirring, 1600 parts by weight of the swollen polymer are added, the temperature is raised to 60 ± 1 °C, the pressure is kept at atmospheric pressure, 0.5 - 0.6 part by weight of sodium persulfate and 0.5 - 0.6 part by weight of sodium bisulfite are added. After stirring evenly, the pre - emulsion is continuously added dropwise, and the dropping speed is controlled to be completed within 1.8 h - 2 h; among them, when the dropping reaches 1.5 h, 12 parts by weight of zinc hydroxy stannate are started to be added dropwise and controlled to be added dropwise within 0.5 h;

[0055] Kept warm for 1 h, 0.4 part by weight of vitamin C and 0.8 part by weight of tert - butyl hydroperoxide are added, stirred for 30 min, degassed, cooled to 35 °C, the pH is adjusted to about 8 with ammonia water, and 4 parts by weight of bactericide are added and stirred evenly to obtain the emulsion;

[0056] Step Three: Coating Preparation

[0057] 30 parts by weight of water are added into the container, the rotation speed is adjusted to 1000 rpm, and 0.5 part by weight of dispersant 5040, 0.3 part by weight of wetting agent, 0.2 part by weight of mineral oil defoamer, and 1 part by weight of lauryl alcohol ester are added in sequence and stirred evenly;

[0058] The rotation speed is adjusted to 1500 rpm, 0.2 part by weight of cellulose is added, and stirred until completely dispersed;

[0059] Maintain the rotation speed at 1500 rpm, and sequentially add 5 parts by weight of rutile titanium dioxide, 10 parts by weight of calcined kaolin, and 22 - 30 parts by weight of heavy calcium carbonate, and stir and disperse for 30 min;

[0060] Reduce the rotation speed to 1000 rpm, add 10 parts by weight of expanded vermiculite, 0 - 8 parts by weight of ammonium polyphosphate, and 2 parts by weight of multifunctional amine auxiliary agent, and stir evenly;

[0061] Reduce the rotation speed to 500 - 700 rpm, add 20 parts by weight of the said emulsion, 0.2 parts by weight of fungicide, 0.1 parts by weight of defoamer, and 1 part by weight of ethylene glycol. After stirring evenly, add polyurethane thickener and acrylic thickener to make the viscosity about 8000 cp, continue to stir for 10 min, filter and discharge to obtain the intrinsic fire - resistant waterborne coating.

[0062] To understand the technical solution of this application more clearly, the technical solution of this application will be introduced in detail below in combination with specific embodiments of this application.

[0063] Example 1

[0064] Swelling polymerization

[0065] Prepare each component according to Table 1.

[0066] Table 1

[0067]

[0068] After the material preparation is completed, for each component corresponding to each implementation serial number, perform swelling polymerization respectively according to the following steps:

[0069] ①. Add the materials numbered 1, 2, and 3 into a 30 - liter polymerization kettle under stirring, heat the polymerization kettle to 60 - 65 °C, keep it warm for 8 - 10 h, and maintain slow stirring during this period, with a speed of 3 - 5 rpm;

[0070] ②. Add the material numbered 4, stir for 10 - 15 min, heat up to 80 - 85 °C, and maintain the stirring speed at 3 - 5 rpm;

[0071] ③. Raise the stirring speed to 10 - 15 rpm, add the materials numbered 5 and 6, and carry out the polymerization reaction, keeping the pressure at atmospheric pressure;

[0072] ④. After the addition is completed, keep the temperature (80 - 85 °C) and stirring speed (10 - 15 rpm) for 30 min, then cool to room temperature for standby to obtain the swollen polymer.

[0073] Among them, the parameters of the polyvinyl chloride seed emulsion in Table 1 are: solids content 30 - 35%, pH 9 - 11, median particle size (D50) 70 - 100 nm, and the polyvinyl chloride seed emulsions used in implementation serial numbers 1 - 9 in Table 1 are the same and have the same parameter values; while the emulsifier (sodium dodecylbenzenesulfonate) is an aqueous solution with a solids content of 20%.

[0074] In steps ① - ④, adding material 2 is to emulsify materials 3 and 4 (oily substances) so that they are dispersed in material 1 (oily substances need to be dispersed in the aqueous substance with an emulsifier). If more of material 2 is added, the particle size will be relatively smaller, but the initial water resistance of the film will be worse.

[0075] Adding material 3 (the polymer of material 3 can form a film at low temperature) is used as a plasticizer to swell the surface of the particles of the material 1 seed emulsion. After material 3 swells on the surface of the sub - emulsion particles, the temperature is raised for polymerization to improve the film - forming performance of the seed emulsion in the final emulsion product.

[0076] Material 4, as a cross - linking monomer, forms an interpenetrating cross - linked network between the core and the shell, increasing the interaction force between the core and the shell, and reducing the internal stress caused by the different film - forming rates between the core and the shell during the film - forming process (a large internal stress will cause small cracks to appear in the film during the film - forming process and make it opaque, and the mechanical properties of the film will decrease significantly). Thus, the film becomes a uniform and transparent film. With good film - forming performance, comprehensive properties such as the transparency, tensile strength, elongation at break, and water resistance of the film will be significantly improved.

[0077] Materials 5 and 6 are initiators. After the temperature rises to a certain level, the monomers are polymerized by adding the initiators.

[0078] The 9 kinds of swollen polymers prepared according to the components shown in Table 1 and the aforementioned steps ① - ④ are tested, and the test results are shown in Table 2.

[0079] Table 2

[0080]

[0081] Comparing the results in Table 2, the swollen polymer corresponding to implementation serial number 4 is the best. Its film - forming situation is transparent and crack - free, and the initial water resistance situation shows a blue - white color (indicating good initial water resistance of the film). The corresponding added material has a relatively large addition of butyl acrylate to promote film - forming, and a relatively small addition of sodium dodecylbenzenesulfonate.

[0082] Example 2

[0083] Emulsion polymerization

[0084] Select the swollen polymer corresponding to implementation serial number 4 in Example 1 for the following operations.

[0085] Prepare each component as shown in Table 3.

[0086] Table 3

[0087]

[0088] The emulsion after swelling polymerization with the serial number 1 in Table 3 corresponds to the one obtained in Example 1 with the implementation serial number 4.

[0089] After the material preparation is completed, let each component corresponding to each implementation serial number carry out emulsion polymerization respectively according to the following steps:

[0090] ①. Add 80% of the material with the serial number 2 into the pre-emulsification tank, add the materials with the serial numbers 3 and 4 during stirring, and then add the materials with the serial numbers 5 - 8, and stir evenly to obtain a pre-emulsified liquid for standby;

[0091] ②. Add 20% of the material with the serial number 2 into the polymerization kettle, add the material with the serial number 1 during stirring, heat up to 60 ± 1 °C, and keep the pressure at normal pressure;

[0092] ③. Add the materials with the serial numbers 9 and 10, stir evenly and then continuously dropwise add the pre-emulsified liquid prepared in the first step, and the polymerization reaction starts. Control the dropping rate to finish dropping within 1.8 - 2 h;

[0093] ④. Start dropping the material with the serial number 13 when the dropping in the third step reaches 1.5 h, and control to finish dropping within 0.5 hour;

[0094] ⑤. After all dropping is completed, keep warm for 1 h, add the materials with the serial numbers 11 and 12, stir for 30 min, degas, cool down to 35 °C, adjust the pH of the emulsion to about 8 with ammonia water, and add a bactericide and stir evenly to obtain the required emulsion.

[0095] In this example, in order to smoothly achieve polymerization, the polymerization formula in Table 3 is not adjusted within a large range. The main purpose is to adjust the water resistance and fire resistance after film formation, which is achieved by adjusting materials 3, 4, 5, and 8, and the rest of the materials remain unchanged.

[0096] Both materials 3 and 4 are emulsifiers, and the total amount is kept at a certain level. The addition amounts of the two are adjusted to each other to ensure water resistance (material 3) and fire resistance (material 4). If more material 3 is added, although it helps the stable progress of the emulsion polymerization process, it is likely to cause poor initial water resistance of the finished film.

[0097] If more material 4 is added, although it is helpful for the fire resistance of the finished product, its emulsifying performance is weaker than that of material 3, and adding more is not conducive to the stable progress of the polymerization process.

[0098] Material 5 is used to ensure the film formation of the finished product.

[0099] Material 8 is a phosphorus-containing monomer, which is beneficial for fire prevention, but a certain balance must be maintained between 5 and 8.

[0100] Deionized water is used as a carrier to disperse the materials in the formulation.

[0101] Materials 6 and 7 are also polymerization monomers, and together with materials 5 to 8, they adjust the film-forming temperature of the finished product.

[0102] Materials 9 and 10 are initiators, while materials 11 and 12 serve as post-treatment agents to improve monomer conversion. Material 13 is added to the polymerization reaction to coat the particle surface, trapping any hydrogen chloride generated by thermal decomposition of the PVC in the film that could potentially escape and cause harm in the event of a fire.

[0103] The nine products prepared according to the components shown in Table 3 and steps ① to ⑤ above were tested, and the test results are shown in the following table.

[0104] Table 4

[0105]

[0106] As shown in Table 4, the emulsion obtained in Example 6 forms a transparent film on the glass plate without cracks, turns blue and white when soaked in water, and has the best water resistance. The emulsion obtained in Example 6 is selected for the preparation of the third step fire retardant coating. Figure 1 As shown in the figure, the photo of the emulsion after film formation is as follows Figure 2 shown.

[0107] Example 3

[0108] Coating preparation

[0109] The following operations were performed on the product obtained corresponding to implementation number 6 in Example 2.

[0110] Prepare the components as shown in Table 5.

[0111] Table 5

[0112]

[0113] The third step is to:

[0114] ①. Add material No. 1, adjust the speed to 1000rpm, and add materials No. 2-5 in sequence according to the recipe and stir evenly.

[0115] ②. Adjust the speed to 1500rpm, add material No. 6, add small amounts several times, and stir until completely dispersed;

[0116] ③. Keep the rotation speed at 1500 rpm, add the materials numbered 7 - 9 in sequence, and stir and disperse for 30 min after addition;

[0117] ④. Reduce the rotation speed to 1000 rpm, add the materials numbered 10 - 12, and stir evenly;

[0118] ⑤. Reduce the rotation speed to 500 - 700 rpm, add the materials numbered 13 - 16, stir evenly, adjust the matrix viscosity to about 8000 cp with the materials numbered 17 - 18, continue to stir for 10 min, and filter and discharge;

[0119] Test the 9 products prepared according to the components shown in Table 5 and the aforementioned steps ① - ⑤ (detect according to the standard of GB14907 - 2018 intumescent indoor steel structure fire - retardant coating), and the test results are shown in Table 6.

[0120] Table 6

[0121]

[0122] It can be seen from Table 6 that the product corresponding to the implementation serial number 5 has the highest bond strength; it can be known from the product corresponding to the implementation serial number 1 that without adding flame - retardant additives, the fire - resistance limit can still reach 1 h; the fire - resistance limits of the products corresponding to the implementation serial numbers 2 - 7 are at the same level, and adding flame - retardant agents helps with the flame - retardant effect. Considering the products corresponding to the implementation serial numbers 1 - 9 comprehensively, it can be known that the fire - retardant coating prepared by the aforementioned method can achieve certain flame - retardant performance with less or even no addition of flame - retardant agents.

[0123] According to the fire - retardant coating preparation formulas of the implementation serial numbers 1 and 5, select normal styrene - acrylic emulsions on the market: Badfu (model: RS - 996KD) and Wanhua emulsion (model: Wantipro 0624) to prepare fire - retardant coatings (that is, replace the emulsion with the material serial number 13 in Table 5 with Badfu and Wanhua emulsions respectively), and the test results are shown in Table 7.

[0124] Table 7

[0125]

[0126] It can be seen from Table 7 that for the fire - retardant coatings prepared with the two emulsions on the market, their bond strength and water resistance are slightly better than those of the fire - retardant coatings prepared with the emulsion of this patent under the same conditions, but they are all within the qualified range. Without adding flame - retardant additives, the fire - resistance limit is less than 0.5 h, which cannot meet the fire - prevention and flame - retardant requirements. After adding a small amount of flame - retardant additives, the fire - resistance limit increases to some extent, but it is still significantly inferior to the fire - retardant coatings prepared with the emulsion of this patent.

[0127] Prepare three fire - retardant coatings according to the fire - retardant coating preparation formula corresponding to the implementation serial number 5 in Table 7. Among them:

[0128] The material corresponding to Material Serial No. 13 in Table 5 of Fireproof Coating 1 is the product obtained corresponding to Implementation Serial No. 6 in Example 2;

[0129] The material corresponding to Material Serial No. 13 in Table 5 of Fireproof Coating 2 is RS-996KD;

[0130] The material corresponding to Material Serial No. 13 in Table 5 of Fireproof Coating 3 is Wantipro 0624.

[0131] The oxygen index tests were carried out on the three fireproof coatings, and the test results are shown in Table 8.

[0132] Table 8

[0133] Sample Serial Number Fireproof Coating 1 Fireproof Coating 2 Fireproof Coating 3 Oxygen Index 30.0 23.0 21.5

[0134] It can be seen from Table 8 that Fireproof Coating 1 has a higher oxygen index, that is, it has better flame retardancy.

[0135] Among them, the basis for the oxygen index test is: The oxygen index of the coating is tested according to "GB-T 2046.2-2009 Plastics-Determination of burning behavior by the oxygen index method". The oxygen index (OI) refers to the minimum oxygen concentration at which the material just maintains combustion in a mixed gas of oxygen and nitrogen under specified conditions (23±2°C), expressed as a volume fraction. The higher the oxygen index, the better the flame retardant performance. The top surface ignition method is adopted, and the oxygen content is adjusted so that it burns from the top to 50 mm below the bottom in 180 s, and the oxygen content at this time is the oxygen index.

[0136] Such as Figure 3 , from the test plate results of the coatings obtained corresponding to RS-996KD, the coating obtained corresponding to Implementation Serial No. 6 in Example 2, and the coating obtained corresponding to Wantipro0624, it can be seen that the product obtained corresponding to Implementation Serial No. 6 in Example 2 is finer, has a smaller particle size, and has fewer pores in the film after the test plate.

[0137] Such as Figure 4 , from the combustion results of the coatings obtained corresponding to RS-996KD, the coating obtained corresponding to Implementation Serial No. 6 in Example 2, and the coating obtained corresponding to Wantipro0624, the resin emulsion prepared by the present invention swells most significantly after combustion, and almost no carbonized layer falls off.

[0138] Such as Figure 5, in the fireproof coating obtained in this application, the PVC prepolymer is used as the "core", and the resin emulsion particles are coated on the outside as the "shell"; at high temperatures, PVC decomposes when heated to release HCl gas, which enters the particle surface layer, causing the surface layer to foam, and the surface layer undergoes carbonization while being heated. Methacryloyloxyethyl phosphate is a phosphorus-containing monomer, which plays a synergistic fireproof role with the phosphorus-containing emulsifier RS-610. After the HCl gas enters the particle surface layer, it reacts with the zinc hydroxy stannate on the surface layer to be converted into harmless salts to humans, realizing the harmless conversion of HCl gas.

[0139] It should be noted that in this text, the term "including", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such a process, method, article or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0140] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of an intrinsic fireproof waterborne coating, characterized in that, The preparation method includes the following steps: Step 1: Swelling polymerization Add 1600 parts by weight of polyvinyl chloride seed emulsion, 5 - 8 parts by weight of emulsifier, and 60 - 80 parts by weight of swelling monomer into the polymerization kettle at one time under stirring. Heat the polymerization kettle to 60 - 65 °C, keep warm for 8 - 10 h, and continuously stir during this period at a speed of 3 - 5 rpm. Add 10 - 20 parts by weight of vinyltrimethoxysilane, stir for 10 - 15 min, and then heat to 80 - 85 °C at a speed of 3 - 5 rpm. Raise the stirring speed to 10 - 15 rpm, add 0.1 part by weight of sodium sulfate and 0.1 part by weight of sodium bisulfate persulfate, carry out the polymerization reaction, keep the pressure at atmospheric pressure, keep warm and continuously stir for 30 min, and then cool to room temperature for standby to obtain the swollen polymer. Step 2: Emulsion polymerization Add 160 parts by weight of deionized water into the pre-emulsification tank. During stirring, first add 15 - 20 parts by weight of emulsifier and 22 - 25 parts by weight of phosphorus-containing emulsifier, and then add 190 - 220 parts by weight of butyl acrylate, 150 parts by weight of methyl methacrylate, 80 parts by weight of acrylic acid, and 105 - 110 parts by weight of methacryloyloxyethyl phosphate, and stir evenly to obtain the pre-emulsion for standby. Add 40 parts by weight of deionized water into the polymerization kettle. During stirring, add 1600 parts by weight of the swollen polymer, heat to 60 ± 1 °C, keep the pressure at atmospheric pressure, add 0.5 - 0.6 part by weight of sodium persulfate and 0.5 - 0.6 part by weight of sodium bisulfite, stir evenly, and then continuously dropwise add the above-mentioned pre-emulsion, and control the dropping speed to complete the dropping within 1.8 h - 2 h. Among them, when the dropping reaches 1.5 h, start to dropwise add 12 parts by weight of zinc hydroxystannate and control to complete the dropping within 0.5 h. Keep warm for 1 h, add 0.4 part by weight of vitamin C and 0.8 part by weight of tert-butyl hydroperoxide, stir for 30 min, degas, cool to 35 °C, adjust the pH to 8 with ammonia water, add 4 parts by weight of bactericide and stir evenly to obtain the emulsion. Step 3: Coating preparation Add 30 parts by weight of water into the container, adjust the rotation speed to 1000 rpm, and sequentially add 0.5 part by weight of dispersant 5040, 0.3 part by weight of wetting agent, 0.2 part by weight of mineral oil defoamer, and 1 part by weight of lauryl alcohol ester, and stir evenly. Adjust the rotation speed to 1500 rpm, add 0.2 part by weight of cellulose, and stir until completely dispersed. Keep the rotation speed at 1500 rpm, and sequentially add 5 parts by weight of rutile titanium dioxide, 10 parts by weight of calcined kaolin, and 22 - 30 parts by weight of heavy calcium, and stir and disperse for 30 min. Reduce the rotation speed to 1000 rpm, add 10 parts by weight of expanded vermiculite, 0 - 8 parts by weight of ammonium polyphosphate, and 2 parts by weight of multifunctional amine additive, and stir evenly. Reduce the rotational speed to 500 - 700 rpm, add 20 parts by weight of the said emulsion, 0.2 parts by weight of a bactericide, 0.1 parts by weight of an antifoaming agent and 1 part by weight of ethylene glycol. After stirring evenly, add a polyurethane thickener and an acrylic thickener to make the viscosity reach 8000 cp, continue stirring for 10 min, filter and discharge to obtain the said intrinsic fireproof waterborne coating.

2. The preparation method according to claim 1, characterized in that, The parameters of the said polyvinyl chloride seed emulsion are: solid content 30 - 35%, pH 9 - 11, median particle size 70 - 100 nm.

3. The preparation method according to claim 1, characterized in that, The said emulsifier is an aqueous solution of sodium dodecylbenzenesulfonate with a solid content of 20%.

4. The preparation method according to claim 1, wherein, The said swelling monomer is butyl acrylate.

5. The preparation method according to claim 1, wherein, The said phosphorus-containing emulsifier is Solvay RS610.

6. The preparation method according to claim 1, characterized in that, The initiator used in the emulsion polymerization in step two is the redox system low-temperature initiator sodium persulfate and sodium bisulfite.

7. The preparation method according to claim 1, characterized in that, The addition amount of the said ammonium polyphosphate is zero.

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