A method for preparing a transparent wood fire-retardant coating

Abstract

This invention discloses a method for preparing a transparent fire-retardant wood coating, belonging to the field of coating technology. The transparent fire-retardant wood coating includes an inner coating and an outer coating. The preparation method of the inner coating is as follows: a flexible flame retardant is dissolved in water, and tea polyphenol crystals are added to form a flame-retardant mixture; then, it is mixed evenly with an amino resin to obtain a transparent fire-retardant inner coating. The preparation method of the outer coating includes: first, preparing a sulfur-containing all-organic high-refractive-index polymer by catalytic polymerization of bromoalkanes and dithiophenol monomers using an organic base; then, dissolving the polymer in a transparent organic solvent to obtain a high-refractive-index polymer solution; grinding ammonium polyphosphate and pentaerythritol and mixing them evenly with a polysiloxane emulsion to obtain a fire-retardant mixture; finally, adding the high-refractive-index polymer solution, a film-forming aid, and an amino resin to the fire-retardant mixture to obtain a transparent fire-retardant outer coating. This invention achieves good UV resistance in addition to transparency and fire resistance.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to a method for preparing a transparent wood fire-retardant coating. Background Technology

[0002] Wood is generally used in timber-framed buildings, cultural relics, gardens, architectural decoration, and furniture, possessing a certain decorative quality. However, it often lacks fire resistance, making it difficult to effectively control fire hazards. This has led to the development of decorative fire-retardant coatings that combine decorative and fire-resistant functions. These coatings are applied to the surface of combustible substrates such as wood, fiberboard, or cardboard, providing both fire-retardant protection and decoration. Normally, they serve a decorative purpose, while in the event of a fire, they prevent the spread of fire, thus protecting the combustible substrate.

[0003] In the prior art, patent CN 104497782 B discloses a method for preparing a three-component decorative transparent fire-retardant coating. Component A is prepared using melamine, hydroguanidine, urea, and formaldehyde; component B is prepared using APP II and pentaerythritol; and component C uses acetic acid as an auxiliary acid source and also as a diluent. The three components are mixed to obtain the decorative transparent fire-retardant coating. However, this coating has the following problems:

[0004] For outdoor wooden structures, daily sun exposure, especially the effects of ultraviolet (UV) radiation, can cause the wood to warp, discolor, and crack. The aforementioned protective coatings do not have the function of mitigating UV damage. Furthermore, once existing wood protective coatings are applied, all parts of the coating work simultaneously, failing to achieve a sequential, composite protective effect, and thus cannot provide adequate UV resistance. Summary of the Invention

[0005] The present invention addresses the problem that existing technical solutions are too simplistic and provides a solution that is significantly different from existing technologies. It mainly provides a method for preparing a transparent wood fire-retardant coating, thereby solving the technical problem mentioned in the background that existing wood protective coatings cannot achieve good UV resistance.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0007] A method for preparing a transparent wood fire-retardant coating, wherein the transparent wood fire-retardant coating comprises an inner coating layer and an outer coating layer;

[0008] The preparation method of the inner coating includes the following steps:

[0009] A1. Dissolve the flexible flame retardant in water and add tea polyphenol crystals to make a flame retardant mixture;

[0010] A2. Mix the flame retardant mixture with amino resin evenly to obtain a transparent fireproof inner coating.

[0011] The preparation method of the outer coating includes the following steps:

[0012] B1. Prepare sulfur-containing all-organic high-refractive-index polymers by catalytic polymerization of bromoalkanes and dithiophenol monomers using organic bases.

[0013] B2. Dissolve a sulfur-containing all-organic high-refractive-index polymer in a transparent organic solvent to obtain a high-refractive-index polymer solution.

[0014] B3. After grinding ammonium polyphosphate and pentaerythritol, mix them evenly with polysiloxane emulsion to obtain a fire-retardant mixture;

[0015] B4. Add a high refractive index polymer solution, film-forming aid, and amino resin to the fireproof mixture and mix thoroughly to obtain a transparent fireproof outer coating.

[0016] Specifically, in step A1, the preparation method of the flexible flame retardant is as follows:

[0017] A1-1. Phosphate ester is prepared by heating a mixture of phosphorus source and carbon source; the mass ratio of phosphorus source to carbon source is 1:(0.3-0.5), the heating temperature is 100-120℃, and the heating time is 4-6h; the phosphorus source is selected from any one of phosphoric acid, ammonium polyphosphate, phosphorus oxychloride, chloroethanol phosphate, chlorinated phosphate ester, and polyphosphoric acid; the carbon source is selected from any one of pentaerythritol, starch, triazine compounds, neopentyl glycol, and diethanolamine.

[0018] A1-2. The phosphate ester and halloysite nanotubes are mixed at a mass ratio of 1:(0.01-0.1), and then heated at 50°C for 30 min to obtain the modified phosphate ester.

[0019] A1-3. Mix modified phosphate ester and polyethylene glycol at a mass ratio of 1:(0.2-0.5), heat at 50°C for 1 hour, and then heat at 120°C for 4 hours to obtain a flexible flame retardant.

[0020] Further, in step A1, after the flexible flame retardant is dissolved in water, the mass fraction of the resulting flexible flame retardant aqueous solution is 40-60 wt%, and the amount of tea polyphenol crystals added is 4-10% of the weight of the flexible flame retardant aqueous solution.

[0021] Further, in step A2, the mass ratio of the flame retardant mixture to the amino resin is 1:(1.0-1.5).

[0022] Furthermore, in step B1, the reaction temperature is 80°C, the monomer concentration is 0.2M, the solvent is dimethyl sulfoxide (DMSO), and the reaction time is 4 hours.

[0023] Furthermore, in step B2, the organic solvent is dimethylamide or dichloromethane.

[0024] Specifically, step B3 includes:

[0025] B3-1. Deionized water, defoamer, dispersant, ammonium polyphosphate and pentaerythritol are added to the stirring device in sequence and stirred at 1500-2000 r / min for 20-30 min. Then, the mixture is ground in a three-roll mill for 2-3 h to obtain a preliminary mixture.

[0026] B3-2. Place the preliminary mixture into a disperser and disperse it at a speed of 1500-2000 r / min, while adding polysiloxane emulsion to mix evenly.

[0027] Further, in step B3-1, the mass ratio of deionized water, defoamer, dispersant, ammonium polyphosphate and pentaerythritol is 1:0.1:0.3:25:15; in step B3-2, the amount of polysiloxane emulsion added is 7 / 25 of the weight of ammonium polyphosphate.

[0028] Further, step B4 specifically involves: reducing the speed of the disperser containing the fire-retardant mixture to 500-800 r / min, adding film-forming aids, amino resin, defoamer, thickener, leveling agent, light stabilizer, and high refractive index polymer solution, and mixing evenly to obtain a transparent fire-retardant outer coating.

[0029] Furthermore, the mass ratio of the film additive, amino resin, defoamer, thickener, leveling agent, light stabilizer, and high refractive index polymer solution is 0.3:50:0.2:0.3:0.3:0.3:0.3, and the ratio of the amount of amino resin to polysiloxane emulsion is 50:7.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] (1) This invention comprises an inner coating and an outer coating, wherein the outer coating contains a fully organic high-refractive-index polymer, and the inner coating contains tea polyphenols. In application, sunlight first shines on the outer coating, utilizing the high refractive index and high reflectivity of the fully organic high-refractive-index polymer to achieve a good UV resistance effect, significantly reducing the amount of UV light passing through the outer coating; then, the inner coating absorbs some of the UV light through the UV absorption capacity of tea polyphenols, further reducing the amount of UV light contacting the wood structure. Thus, this invention achieves a good UV resistance effect through the combined refraction, reflection, and absorption of UV light by the inner and outer coatings, effectively preventing wood from deforming, discoloring, or cracking due to UV radiation.

[0032] (2) The present invention includes an inner coating and an outer coating, and both the inner coating and the outer coating have the properties of transparency, flame retardancy and certain UV resistance. Therefore, for wood structures in environments with weak UV intensity, either the inner coating or the outer coating in the present invention can be used alone.

[0033] The present invention will be explained in detail below through specific embodiments. Detailed Implementation

[0034] To facilitate understanding of the present invention, a more comprehensive description will be given below. The present invention can be implemented in different forms and is not limited to the embodiments described in the text. Rather, these embodiments are provided to make the disclosure of the present invention more thorough and complete.

[0035] Example 1: A transparent wood fire-retardant coating, comprising an inner coating and an outer coating.

[0036] The preparation method of the inner coating includes the following steps:

[0037] A1. Phosphate ester is prepared by mixing and heating a phosphorus source and a carbon source; the mass ratio of phosphorus source to carbon source is 1:0.5, the heating temperature is 100℃, and the time is 6h; the phosphorus source is ammonium polyphosphate, and the carbon source is pentaerythritol.

[0038] A2. Mix phosphate ester and halloysite nanotubes at a mass ratio of 1:0.01, and then heat at 50°C for 30 min to obtain modified phosphate ester.

[0039] A3. Mix modified phosphate ester and polyethylene glycol at a mass ratio of 1:0.3, heat at 50°C for 1 hour, and then heat at 120°C for 4 hours to obtain a flexible flame retardant.

[0040] A4. Dissolve the flexible flame retardant in water to obtain a flexible flame retardant aqueous solution with a mass fraction of 40-60 wt%. Then add tea polyphenol crystals to make a flame retardant mixture. The amount of tea polyphenol crystals added is 4% of the weight of the flexible flame retardant aqueous solution.

[0041] A5. Mix the flame retardant mixture with amino resin evenly to obtain a transparent fireproof inner coating. The mass ratio of the flame retardant mixture to the amino resin is 1:1.0.

[0042] The preparation method of the outer coating includes the following steps:

[0043] B1. A sulfur-containing all-organic high-refractive-index polymer was prepared by catalytic polymerization of bromoalkanes and dithiophenol monomers using an organic base. The reaction temperature was 80℃, the monomer concentration was 0.2M, the solvent was dimethyl sulfoxide (DMSO), and the reaction time was 4 hours.

[0044] B2. Dissolve a sulfur-containing all-organic high-refractive-index polymer in a transparent organic solvent to obtain a high-refractive-index polymer solution. The organic solvent is dimethylamide.

[0045] B3. After grinding ammonium polyphosphate and pentaerythritol, mix them evenly with polysiloxane emulsion to obtain a fire-retardant mixture;

[0046] B3-1. Deionized water, defoamer A203E, dispersant SP-762, ammonium polyphosphate, and pentaerythritol are added sequentially to a stirring device and stirred at 1500 r / min for 30 min. Then, the mixture is ground in a three-roll mill for 2 h to obtain a preliminary mixture. The mass ratio of deionized water, defoamer A203E, dispersant SP-762, ammonium polyphosphate, and pentaerythritol is 1:0.1:0.3:25:15.

[0047] B3-2. Place the preliminary mixture into a disperser and disperse it at a speed of 1500 r / min. At the same time, add polysiloxane emulsion to mix evenly. The amount of polysiloxane emulsion added is 7 / 25 of the weight of ammonium polyphosphate.

[0048] B4. Reduce the speed of the disperser containing the fire-retardant mixture to 500 r / min, add film-forming aid PPH, amino resin, defoamer A203E, thickener XS-167, leveling agent XS-12, light stabilizer UV1130, and high refractive index polymer solution, and mix evenly to obtain a transparent fire-retardant outer coating; the mass ratio of film-forming aid PPH, amino resin, defoamer A203E, thickener XS-167, leveling agent XS-12, light stabilizer UV1130, and high refractive index polymer solution is 0.3:50:0.2:0.3:0.3:0.3:0.3, and the ratio of the amount of amino resin to the aforementioned polysiloxane emulsion is 50:7.

[0049] The sulfur-containing all-organic high-refractive-index polymer in the outer coating has a refractive index as high as 1.8433 at 589 nm, and has good optical transparency in the visual and RI regions, even in the range of 100 micrometers. The high refractive index gives it good reflectivity, thus enabling it to play a role in resisting ultraviolet rays.

[0050] The absorption spectrum of tea polyphenols shows an absorption peak in the ultraviolet region. The absorption peak of tea polyphenols is usually in the range of 200-400 nanometers, indicating that tea polyphenols have the function of absorbing ultraviolet light.

[0051] When applied, sunlight first shines on the outer coating, where the high refractive index and high reflectivity of the all-organic high-refractive-index polymer achieve a good UV resistance effect, significantly reducing the amount of UV rays passing through the outer coating. Then, the inner coating absorbs some of the UV rays through the UV absorption capacity of tea polyphenols, further reducing the amount of UV rays contacting the wood structure, thus achieving a good UV resistance effect and effectively preventing the wood from deforming, discoloring, cracking, etc. due to the action of UV rays.

[0052] The outer coating utilizes a compound of polysiloxane emulsion, ammonium polyphosphate, and pentaerythritol. The unique polysiloxane branched and multifunctional structure of the polysiloxane emulsion gives it good compatibility with amino resins. At the same time, the contact angle of its multifunctional groups gives ammonium polyphosphate and pentaerythritol better dispersibility. As a result, the transparent fireproof coating for wooden buildings of this invention has good fire resistance, a transparent coating, can maintain the original appearance of the material, is not easy to crack, and has good weather resistance.

[0053] The flexible flame retardant in the inner coating has good flame retardant properties, which significantly reduces the fire hazard of wooden structures.

[0054] Example 2: The difference between this example and Example 1 is that:

[0055] The preparation method of the inner coating includes the following steps:

[0056] A1. Phosphate ester is prepared by mixing and heating a phosphorus source and a carbon source; the mass ratio of phosphorus source to carbon source is 1:0.3, the heating temperature is 110℃, and the time is 5h; the phosphorus source is chloroethanol phosphate, and the carbon source is starch.

[0057] A2. Mix phosphate ester and halloysite nanotubes at a mass ratio of 1:0.05, and then heat at 50°C for 30 min to obtain modified phosphate ester.

[0058] A3. Mix modified phosphate ester and polyethylene glycol at a mass ratio of 1:0.5, heat at 50°C for 1 hour, and then heat at 120°C for 4 hours to obtain a flexible flame retardant.

[0059] A4. Dissolve the flexible flame retardant in water to obtain a flexible flame retardant aqueous solution with a mass fraction of 40-60 wt%, then add tea polyphenol crystals to prepare a flame retardant mixture. The amount of tea polyphenol crystals added is 7% of the weight of the flexible flame retardant aqueous solution.

[0060] A5. Mix the flame retardant mixture with amino resin evenly to obtain a transparent fireproof inner coating. The mass ratio of the flame retardant mixture to amino resin is 1:1.5.

[0061] The preparation method of the outer coating includes the following steps:

[0062] B1. A sulfur-containing all-organic high-refractive-index polymer was prepared by catalytic polymerization of bromoalkanes and dithiophenol monomers using an organic base. The reaction temperature was 80℃, the monomer concentration was 0.2M, the solvent was dimethyl sulfoxide (DMSO), and the reaction time was 4 hours.

[0063] B2. Dissolve a sulfur-containing all-organic high-refractive-index polymer in a transparent organic solvent to obtain a high-refractive-index polymer solution. The organic solvent is dichloromethane.

[0064] B3. After grinding ammonium polyphosphate and pentaerythritol, mix them evenly with polysiloxane emulsion to obtain a fire-retardant mixture;

[0065] B3-1. Deionized water, defoamer A203E, dispersant SP-762, ammonium polyphosphate, and pentaerythritol are added sequentially to a stirring device and stirred at 2000 r / min for 20 min. Then, the mixture is ground in a three-roll mill for 3 h to obtain a preliminary mixture. The mass ratio of deionized water, defoamer A203E, dispersant SP-762, ammonium polyphosphate, and pentaerythritol is 1:0.1:0.3:25:15.

[0066] B3-2. Place the preliminary mixture into a disperser and disperse it at a speed of 2000 r / min. At the same time, add polysiloxane emulsion to mix evenly. The amount of polysiloxane emulsion added is 7 / 25 of the weight of ammonium polyphosphate.

[0067] B4. Reduce the speed of the disperser containing the fire-retardant mixture to 800 r / min, add film-forming aid PPH, amino resin, defoamer A203E, thickener XS-167, leveling agent XS-12, light stabilizer UV1130, and high refractive index polymer solution, and mix evenly to obtain a transparent fire-retardant outer coating; the mass ratio of film-forming aid PPH, amino resin, defoamer A203E, thickener XS-167, leveling agent XS-12, light stabilizer UV1130, and high refractive index polymer solution is 0.3:50:0.2:0.3:0.3:0.3:0.3, and the ratio of the amount of amino resin to the aforementioned polysiloxane emulsion is 50:7.

[0068] The rest is the same as in Example 1.

[0069] Example 3: The difference between this example and Example 1 is that:

[0070] The preparation method of the inner coating includes the following steps:

[0071] A1. Phosphate ester is prepared by mixing and heating a phosphorus source and a carbon source; the mass ratio of phosphorus source to carbon source is 1:0.4, the heating temperature is 120℃, and the time is 4h; phosphoric acid is used as the phosphorus source, and diethanolamine is used as the carbon source.

[0072] A2. Mix phosphate ester and halloysite nanotubes at a mass ratio of 1:0.1, and then heat at 50°C for 30 min to obtain modified phosphate ester.

[0073] A3. Mix modified phosphate ester and polyethylene glycol at a mass ratio of 1:0.2, heat at 50°C for 1 hour, and then heat at 120°C for 4 hours to obtain a flexible flame retardant.

[0074] A4. Dissolve the flexible flame retardant in water to obtain a flexible flame retardant aqueous solution with a mass fraction of 40-60 wt%. Then add tea polyphenol crystals to make a flame retardant mixture. The amount of tea polyphenol crystals added is 10% of the weight of the flexible flame retardant aqueous solution.

[0075] A5. Mix the flame retardant mixture with amino resin evenly to obtain a transparent fireproof inner coating. The mass ratio of the flame retardant mixture to amino resin is 1:1.3.

[0076] The preparation method of the outer coating includes the following steps:

[0077] B1. A sulfur-containing all-organic high-refractive-index polymer was prepared by catalytic polymerization of bromoalkanes and dithiophenol monomers using an organic base. The reaction temperature was 80℃, the monomer concentration was 0.2M, the solvent was dimethyl sulfoxide (DMSO), and the reaction time was 4 hours.

[0078] B2. Dissolve a sulfur-containing all-organic high-refractive-index polymer in a transparent organic solvent to obtain a high-refractive-index polymer solution. The organic solvent is dimethylamide.

[0079] B3. After grinding ammonium polyphosphate and pentaerythritol, mix them evenly with polysiloxane emulsion to obtain a fire-retardant mixture;

[0080] B3-1. Deionized water, defoamer A203E, dispersant SP-762, ammonium polyphosphate, and pentaerythritol are added sequentially to a stirring device and stirred at 1500 r / min for 25 min. Then, the mixture is ground in a three-roll mill for 2.5 h to obtain a preliminary mixture. The mass ratio of deionized water, defoamer A203E, dispersant SP-762, ammonium polyphosphate, and pentaerythritol is 1:0.1:0.3:25:15.

[0081] B3-2. Place the preliminary mixture into a disperser and disperse it at a speed of 1500 r / min. At the same time, add polysiloxane emulsion to mix evenly. The amount of polysiloxane emulsion added is 7 / 25 of the weight of ammonium polyphosphate.

[0082] B4. Reduce the speed of the disperser containing the fire-retardant mixture to 500 r / min, add film-forming aid PPH, amino resin, defoamer A203E, thickener XS-167, leveling agent XS-12, light stabilizer UV1130, and high refractive index polymer solution, and mix evenly to obtain a transparent fire-retardant outer coating; the mass ratio of film-forming aid PPH, amino resin, defoamer A203E, thickener XS-167, leveling agent XS-12, light stabilizer UV1130, and high refractive index polymer solution is 0.3:50:0.2:0.3:0.3:0.3:0.3, and the ratio of the amount of amino resin to the aforementioned polysiloxane emulsion is 50:7.

[0083] The rest is the same as in Example 1.

[0084] The transparent wood fire-retardant coating obtained by this invention was subjected to sample preparation and performance testing, as detailed below:

[0085] (1) Small sample combustion performance test:

[0086] The test substrate was ordinary solid wood, measuring 200mm × 200mm × 10mm. Before coating, the sample was thoroughly sanded with 300-mesh fine sandpaper to ensure a smooth and flat surface. The transparent fire-retardant wood coating prepared according to this invention was applied to the sample, with a wet coating amount of 800g / m². 2 The samples were subjected to a combustion test. The test results showed that the samples rapidly expanded and foamed after being heated, forming a dense honeycomb-like carbon layer. The carbon layer expansion ratio was between 150 and 200 times, effectively blocking the spread of flame and heat and protecting the substrate from damage.

[0087] (2) UV resistance performance test:

[0088] The sample coating was applied to a glass slide measuring 60mm × 60mm × 0.5mm using a coating applicator. The coated sample was then dried in a constant temperature drying oven at 60℃. The light transmittance of the sample was measured at 300nm, 360nm, and 560nm using a UV spectrophotometer. An uncoated slide of the same sample was used as a reference sample. The test results are shown in Table 1.

[0089] Table 1 Results of UV Resistance Test

[0090] Experimental protocol 300nm transmittance % 360nm transmittance % 560nm transmittance % Example 1 2.4 3.5 5.1 Example 2 4.7 6.3 9.0 Example 3 3.6 5.4 8.8 Reference sample 40.4 50.1 55.6

[0091] As shown in Table 1, the ultraviolet transmittance of the transparent wood fire-retardant coatings prepared in Examples 1-3 is only less than 16.2% of that of the reference sample. Therefore, the transparent wood fire-retardant coatings prepared in this invention have significant ultraviolet resistance.

[0092] As can be seen from the above, the transparent wood fire-retardant coating prepared by the present invention has excellent flame-retardant and fire-retardant properties and excellent UV resistance.

[0093] The foregoing description provides an exemplary account of the present invention. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other situations without modification, are all within the protection scope of the present invention.

Claims

1. A method for preparing a transparent wood-based fire-retardant coating, characterized in that: The transparent wood fire-retardant coating includes an inner coating layer and an outer coating layer; The preparation method of the inner coating includes the following steps: A1. Dissolve the flexible flame retardant in water and add tea polyphenol crystals to make a flame retardant mixture; A2. Mix the flame retardant mixture with amino resin evenly to obtain a transparent fireproof inner coating. In step A1, the preparation method of the flexible flame retardant is as follows: A1-1. Phosphate ester is prepared by heating a mixture of phosphorus source and carbon source; the mass ratio of phosphorus source to carbon source is 1:(0.3-0.5), the heating temperature is 100-120℃, and the heating time is 4-6h; the phosphorus source is selected from any one of phosphoric acid, ammonium polyphosphate, phosphorus oxychloride, chloroethanol phosphate, chlorinated phosphate ester, and polyphosphoric acid; the carbon source is selected from any one of pentaerythritol, starch, triazine compounds, neopentyl glycol, and diethanolamine. A1-2. The phosphate ester and halloysite nanotubes are mixed at a mass ratio of 1:(0.01-0.1), and then heated at 50°C for 30 min to obtain the modified phosphate ester. A1-3. Mix modified phosphate ester and polyethylene glycol at a mass ratio of 1:(0.2-0.5), heat at 50°C for 1 hour, and then heat at 120°C for 4 hours to obtain a flexible flame retardant. The preparation method of the outer coating includes the following steps: B1. Prepare sulfur-containing all-organic high-refractive-index polymers by catalytic polymerization of bromoalkanes and dithiophenol monomers using organic bases. B2. Dissolve a sulfur-containing all-organic high-refractive-index polymer in a transparent organic solvent to obtain a high-refractive-index polymer solution. B3. After grinding ammonium polyphosphate and pentaerythritol, mix them evenly with polysiloxane emulsion to obtain a fire-retardant mixture; B4. Add a high refractive index polymer solution, film-forming aid, and amino resin to the fireproof mixture and mix thoroughly to obtain a transparent fireproof outer coating.

2. The method for preparing a transparent wood fire-retardant coating according to claim 1, characterized in that: In step A1, after the flexible flame retardant is dissolved in water, the resulting aqueous solution of the flexible flame retardant has a mass fraction of 40-60 wt%, and the amount of tea polyphenol crystals added is 4-10% of the weight of the aqueous solution of the flexible flame retardant.

3. The method for preparing a transparent wood fire-retardant coating according to claim 1, characterized in that: In step A2, the mass ratio of the flame retardant mixture to the amino resin is 1:(1.0-1.5).

4. The method for preparing a transparent wood fire-retardant coating according to claim 1, characterized in that: In step B1, the reaction temperature is 80℃, the monomer concentration is 0.2M, the solvent is dimethyl sulfoxide, and the reaction time is 4 hours.

5. The method for preparing a transparent wood fire-retardant coating according to claim 1, characterized in that: In step B2, the organic solvent is dimethylamide or dichloromethane.

6. The method for preparing a transparent wood fire-retardant coating according to claim 1, characterized in that: Step B3 includes: B3-1. Deionized water, defoamer, dispersant, ammonium polyphosphate and pentaerythritol are added to the stirring device in sequence and stirred at 1500-2000 r / min for 20-30 min. Then, the mixture is ground in a three-roll mill for 2-3 h to obtain a preliminary mixture. B3-2. Place the preliminary mixture into a disperser and disperse it at a speed of 1500-2000 r / min, while adding polysiloxane emulsion to mix evenly.

7. The method for preparing a transparent wood fire-retardant coating according to claim 6, characterized in that: In step B3-1, the mass ratio of deionized water, defoamer, dispersant, ammonium polyphosphate and pentaerythritol is 1:0.1:0.3:25:15; in step B3-2, the amount of polysiloxane emulsion added is 7 / 25 of the weight of ammonium polyphosphate.

8. The method for preparing a transparent wood fire-retardant coating according to claim 6, characterized in that: Step B4 specifically involves reducing the speed of the disperser containing the fire retardant mixture to 500-800 r / min, adding film-forming aids, amino resin, defoamer, thickener, leveling agent, light stabilizer, and high refractive index polymer solution, and mixing them evenly to obtain a transparent fire retardant outer coating.

9. The method for preparing a transparent wood fire-retardant coating according to claim 8, characterized in that: The mass ratio of film-forming aid, amino resin, defoamer, thickener, leveling agent, light stabilizer and high refractive index polymer solution is 0.3:50:0.2:0.3:0.3:0.3:0.3, and the ratio of the amount of amino resin to polysiloxane emulsion is 50:7.