Colorless transparent fireproof coating

Abstract

The invention belongs to the technical field of fireproof coatings, and particularly relates to a colorless transparent fireproof coating. The inner-layer coating is mainly prepared from the following raw materials in parts by weight: 30 to 50 parts of water-based polypropylene resin, 50 to 70 parts of water-based polyurethane resin, 80 to 100 parts of polysiloxane, 1 to 1.5 parts of coalescing agent, 20 to 30 parts of dimethyl sulfoxide, 3 to 5 parts of anionic dispersant, 4 to 6 parts of porous silicon dioxide loaded nano-silver antibacterial agent and 5 to 8 parts of preservative. The outer coating is mainly prepared from the following raw materials in parts by weight: 30-50 parts of water-based polypropylene resin, 50-70 parts of water-based polyurethane resin, 80-100 parts of polysiloxane, 1-1.5 parts of a coalescing agent, 20-30 parts of water, 2-4 parts of hydroxyethyl cellulose, 30-50 parts of a flame retardant and N parts of a cationic dispersant, wherein N is 20-35% of the dosage of the anionic dispersant. The coating is fireproof and corrosion-resistant, and the bonding degree of the inner and outer coatings is high.

Description

Technical Field

[0001] The invention belongs to the technical field of fire retardant coatings, and in particular relates to a colorless and transparent fire retardant coating. Background Art

[0002] Transparent coatings are also called varnishes. They are mainly used in situations where the natural color or gloss of the substrate needs to be maintained, such as the protection and decoration of wood, glass, metal and other surfaces. In the application of transparent coatings in the field of wood, special attention is paid to its antibacterial, antiseptic and flame retardant properties. In the research on transparent coating formulas, the amount of antibacterial agents, preservatives and flame retardants generally accounts for a small proportion of the overall formula. During the coating preparation process, the effects of antibacterial agents, preservatives and flame retardants are often limited by the influence of stirring loss, dispersion uniformity and other factors.

[0003] Therefore, providing a coating that has good antibacterial and anticorrosive effects on wood and excellent flame retardancy is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0004] The purpose of the present invention is to provide a colorless and transparent fire-retardant coating to overcome the shortcomings of the aforementioned prior art. The coating is divided into an inner coating and an outer coating. The inner coating is combined between the grains of the wood products and forms a film to protect the wood products, playing an antibacterial and anti-corrosion role for the wood products. The outer coating mainly plays a flame retardant role, forming a layered protection of the wood products by the coating. The inner layer is mainly used to prevent decay, and the outer layer is mainly used for fire prevention, thereby further improving the service life of the wood products. The two layers are tightly combined and not easy to fall off, and the fire prevention effect of the bonding layer is also excellent.

[0005] The technical solution of the present invention is:

[0006] A colorless and transparent fire-retardant coating, mainly composed of an inner coating and an outer coating, wherein:

[0007] The inner coating is mainly composed of the following raw materials in parts by weight: 30-50 parts of waterborne polypropylene resin, 50-70 parts of waterborne polyurethane resin, 80-100 parts of polysiloxane, 1-1.5 parts of film-forming aid, 20-30 parts of dimethyl sulfoxide, 3-5 parts of anionic dispersant, 4-6 parts of porous silica loaded nano silver antibacterial agent, and 5-8 parts of preservative;

[0008] The inner coating is sprayed in contact with the outer wall of the wood, which has a good antibacterial and anticorrosive effect on the wood. The anionic dispersant and the porous silica-loaded nano-silver antibacterial agent cooperate to disperse the antibacterial agent evenly in the entire coating system. This dispersion uniformity is promoted and stabilized under the action of the solvent dimethyl sulfoxide. At the same time, the combination of the anionic dispersant, the porous silica-loaded nano-silver antibacterial agent and dimethyl sulfoxide can play a good anti-settling effect, without the need to add an additional anti-settling agent.

[0009] The outer coating is mainly composed of the following raw materials in weight fractions: 30-50 parts of water-based polypropylene resin, 50-70 parts of water-based polyurethane resin, 80-100 parts of polysiloxane, 1-1.5 parts of film-forming aid, 20-30 parts of water, 2-4 parts of hydroxyethyl cellulose, 30-50 parts of flame retardant, and N parts of cationic dispersant, where N is 20-35% of the amount of anionic dispersant used;

[0010] The main function of the outer coating is different from the antibacterial and anticorrosive function of the inner coating. It acts outside the inner coating and mainly plays a role in fire retardancy. In the outer coating, compared with the inner coating, although the amount of cationic dispersant is less, combined with the stable dispersing effect of hydroxyethyl cellulose, the flame retardant can be stably dispersed in the entire coating system, and no additional anti-settling agent is needed.

[0011] When in use, the outer wall of the coated object is first coated with the inner layer of paint, and then the outer layer of paint. The spraying method is that the inner layer of paint is sprayed with a thickness of about 15-20 microns. After spraying, it is dried for 5-10 minutes. Then another layer of inner layer of paint can be sprayed in the same way as the first layer. The outer layer of paint can also be sprayed directly, and the spraying thickness is still 15-20 microns. It is dried after spraying.

[0012] Since the inner coating and the outer coating have different composition materials and functions, in order to prevent the inner and outer coatings from being unstable and peeling off, the present invention has conducted in-depth research on the tight bonding coating. In the scheme:

[0013] First, the solvent dimethyl sulfoxide in the inner coating is combined with the solvent in the outer coating. Dimethyl sulfoxide and water can form a stable mixture through dipole-dipole interaction and hydrogen bond interaction. Both are non-flammable raw materials, which improve the fire resistance of the bonding layer. In addition, the introduction of hydroxyethyl cellulose, a compound with multiple hydrogen bond donors and acceptors, can increase the interaction between water and dimethyl sulfoxide, thereby improving the close bonding of the inner coating and the outer coating.

[0014] Secondly, a part of the anionic surfactant in the inner coating reacts with the cationic dispersant in the outer coating, and the dispersants with different charges attract each other to form a more stable adsorption and binding layer, while improving the stability of the dispersion system. However, in order to prevent the complete charge neutralization during the combination of the anionic dispersant and the cationic dispersant, which leads to a decrease in the stability of the dispersion system and aggregation and sedimentation of the particles, the inventors have conducted a lot of research and finally found that when the cationic dispersant in the outer coating is 20-35% of the amount of the anionic dispersant, the dispersants can attract each other without affecting the stability of the dispersion system to form a stable adsorption and binding. In the outer coating, although the amount of cationic molecular dispersant added is small, hydroxyethyl cellulose also plays a certain role in preventing aggregation and sedimentation between particles and improving the suspension stability of the coating.

[0015] Through the above innovative design, the raw materials of the two layers of paint are used to form a combination, which can effectively prevent the problem of unstable bonding between the coatings. At the same time, the fire resistance of the outer layer of the entire paint system is greatly improved, and the antibacterial and anti-corrosion properties of the inner layer are greatly improved.

[0016] Preferably, the film-forming aids of the inner coating and the outer coating are selected from one or more of dodecyl alcohol ester, dipropylene glycol butyl ether, diethylene glycol butyl ether, methyl isobutyl ketone, and glycol butyl ether acetate.

[0017] Preferably, the anionic dispersant is one or more of polycarboxylates, sodium polyacrylate, polyphosphates, sulfonates, and polyether-modified polycarboxylates.

[0018] Preferably, the cationic dispersant is one or more of polyquaternary ammonium salts, polyamines, polyamidoamines, polyethyleneimine and amino-modified polysiloxane.

[0019] Preferably, the preservative of the inner coating is selected from one of isothiazolinone preservatives, benzisothiazolinone preservatives or iodopropynyl butylcarbamate preservatives.

[0020] Preferably, the flame retardant of the outer coating is selected from one of phosphate flame retardants, borate flame retardants, organophosphorus flame retardants or silane flame retardants.

[0021] Preferably, the method for preparing the inner coating comprises the following steps:

[0022] S1: Stir 30-50 parts of waterborne polypropylene resin and 50-70 parts of waterborne polyurethane resin by a stirring device at a stirring speed of 200-300 rpm for 40-60 minutes until the mixture is uniform, to obtain a mixture 1;

[0023] S2: placing 20-30 parts of dimethyl sulfoxide, 3-5 parts of anionic dispersants, 4-6 parts of porous silica-loaded nanosilver antibacterial agents, and 5-8 parts of preservatives in an ultrasonic device, and treating with ultrasound at an ultrasonic power of 600-800 W for 20-30 min to obtain a second mixture;

[0024] S3: Add 80-100 parts of polysiloxane, 1-1.5 parts of film-forming aid and mixture 2 into mixture 1, stir at a speed of 200-500 rpm, and stir for 40-80 minutes until uniform, to obtain the inner coating.

[0025] Preferably, the method for preparing the outer coating comprises the following steps:

[0026] P1: 30-50 parts of waterborne polypropylene resin and 50-70 parts of waterborne polyurethane resin are stirred by a stirring device at a stirring speed of 200-500 rpm for 30-80 minutes until uniform, to obtain mixture three;

[0027] P2: 20-30 parts of water, 2-4 parts of hydroxyethyl cellulose, 30-50 parts of flame retardant, and N parts of cationic dispersant (N is 20-35% of the amount of anionic dispersant) are stirred by a stirring device at a stirring speed of 200-500 rpm for 30-80 minutes to obtain a mixture IV;

[0028] P3: Add 80-100 parts of polysiloxane, 1-1.5 parts of film-forming aid and mixture 4 into mixture 3 and continue mixing at a stirring speed of 200-500 rpm for 30-80 minutes to obtain an outer coating.

[0029] The beneficial effects of the above technical solution are:

[0030] In the present invention, the traditional idea of ​​spraying paint on the outer wall of wood is broken. According to the actual needs in the process of protecting wood products, an inner layer of paint is first applied to the outer wall of the wood product. The inner layer of paint is combined between the grains of the wood product and forms a film to protect the wood product, which has an antibacterial and anti-corrosion effect on the wood product. Then the outer layer of paint is applied. The outer layer of paint mainly plays a flame retardant role, forming a layered protection of the wood product by the paint. The inner layer is mainly used to prevent decay, and the outer layer is mainly used to prevent fire, so as to further increase the service life of the wood product.

[0031] At the same time, in order to prevent the phenomenon of separation and detachment when different components of coatings are combined, in-depth research has been conducted on the tight bonding coating. First, the dimethyl sulfoxide in the inner coating is combined with the water and hydroxyethyl cellulose in the outer coating. The dimethyl sulfoxide and water can form a stable mixture through dipole-dipole interaction and hydrogen bond interaction. Both are non-flammable raw materials, which improve the fire resistance of the bonding layer. In addition, by introducing hydroxyethyl cellulose, a compound with multiple hydrogen bond donors and acceptors, the interaction between water and dimethyl sulfoxide can be increased, thereby improving the tight bonding of the inner and outer coatings; secondly, part of the anionic surfactant in the inner coating acts with the cationic dispersant in the outer coating, and the dispersants with different charges attract each other to form a more stable adsorption bonding layer, while improving the stability of the dispersion system. Through the above innovative design, the raw materials of the two layers of coating are used to form a combination, which effectively prevents the instability of the bonding between the coatings, and at the same time greatly improves the fire resistance of the outer layer of the entire coating system, and greatly improves the antibacterial and anticorrosive properties of the inner layer. DETAILED DESCRIPTION

[0032] Example 1 A coating and a method for preparing the same

[0033] Colorless and transparent fire retardant coating, mainly composed of inner coating and outer coating, including:

[0034] The inner coating is mainly composed of the following raw materials in parts by weight: 42 parts of waterborne polypropylene resin, 60 parts of waterborne polyurethane resin, 94 parts of polysiloxane, 1.3 parts of film-forming aid, 24 parts of dimethyl sulfoxide, 4 parts of anionic dispersant, 5 parts of porous silica loaded nano-silver antibacterial agent, and 7 parts of preservative;

[0035] The outer coating is mainly composed of the following raw materials in weight fractions: 42 parts of water-based polypropylene resin, 60 parts of water-based polyurethane resin, 94 parts of polysiloxane, 1.3 parts of film-forming aid, 24 parts of water, 3 parts of hydroxyethyl cellulose, 40 parts of flame retardant, and 1.2 parts of cationic dispersant;

[0036] In this embodiment, the film-forming aids of the inner layer coating and the outer layer coating are both dipropylene glycol butyl ether, the anionic dispersant is sodium polyacrylate, the cationic dispersant is polyquaternium-10, the preservative of the inner layer coating is kason, and the flame retardant of the outer layer coating is triphenyl phosphate.

[0037] In this embodiment, the preparation method of the inner layer coating comprises the following steps:

[0038] S1: 42 parts of waterborne polypropylene resin and 60 parts of waterborne polyurethane resin were stirred by a stirring device at a stirring speed of 260 rpm for 50 min to obtain a mixture 1;

[0039] S2: 24 parts of dimethyl sulfoxide, 4 parts of anionic dispersant, 5 parts of porous silica-loaded nanosilver antibacterial agent, and 7 parts of preservative are placed in an ultrasonic device, and treated with ultrasound at an ultrasonic power of 700 W for 25 minutes to obtain a mixture II;

[0040] S3: Add 94 parts of polysiloxane, 1.3 parts of film-forming aid and mixture 2 into mixture 1, stir at a speed of 350 rpm, and stir for 60 minutes to obtain the inner layer coating.

[0041] In this embodiment, the method for preparing the outer coating comprises the following steps:

[0042] P1: 42 parts of waterborne polypropylene resin and 60 parts of waterborne polyurethane resin were stirred in a stirring device at a stirring speed of 350 rpm for 55 minutes to obtain mixture three;

[0043] P2: 24 parts of water, 3 parts of hydroxyethyl cellulose, 40 parts of flame retardant, and 1.2 parts of cationic dispersant were stirred by a stirring device, the stirring speed was 350 rpm, and the stirring was performed for 55 minutes to obtain a mixture of four;

[0044] P3: Add 94 parts of polysiloxane, 1.3 parts of film-forming aid and mixture 4 into mixture 3 and continue mixing. The stirring speed is 350 rpm and the stirring time is 55 minutes to obtain the outer coating.

[0045] Example 2 A coating and a method for preparing the same

[0046] Colorless and transparent fire retardant coating, mainly composed of inner coating and outer coating, including:

[0047] The inner coating is mainly composed of the following raw materials in parts by weight: 30 parts of waterborne polypropylene resin, 50 parts of waterborne polyurethane resin, 82 parts of polysiloxane, 1 part of film-forming aid, 20 parts of dimethyl sulfoxide, 3 parts of anionic dispersant, 4 parts of porous silica loaded nano silver antibacterial agent, and 5 parts of preservative;

[0048] The outer coating is mainly composed of the following raw materials in weight fractions: 30 parts of water-based polypropylene resin, 50 parts of water-based polyurethane resin, 82 parts of polysiloxane, 1 part of film-forming aid, 20 parts of water, 2 parts of hydroxyethyl cellulose, 30 parts of flame retardant, and 0.6 parts of cationic dispersant;

[0049] In this embodiment, the film-forming aids of the inner layer coating and the outer layer coating are both selected from methyl isobutyl ketone, the anionic dispersant is ammonium polyacrylate, the cationic dispersant is polyamide epoxy amine, the preservative of the inner layer coating is Dowicil 75, and the flame retardant of the outer layer coating is a silane coupling agent.

[0050] In this embodiment, the preparation method of the inner layer coating comprises the following steps:

[0051] S1: 30 parts of waterborne polypropylene resin and 50 parts of waterborne polyurethane resin are stirred by a stirring device at a stirring speed of 200 rpm for 40 minutes until the mixture is uniform, to obtain a mixture 1;

[0052] S2: 20 parts of dimethyl sulfoxide, 3 parts of anionic dispersant, 4 parts of porous silica-loaded nanosilver antibacterial agent, and 5 parts of preservative are placed in an ultrasonic device and treated with ultrasound at an ultrasonic power of 600 W for 20 minutes to obtain a mixture II;

[0053] S3: Add 82 parts of polysiloxane, 1 part of film-forming aid and mixture 2 into mixture 1, stir at a speed of 200 rpm, and stir for 40 minutes until uniform, to obtain the inner layer coating.

[0054] In this embodiment, the method for preparing the outer coating comprises the following steps:

[0055] P1: 30 parts of waterborne polypropylene resin and 50 parts of waterborne polyurethane resin were stirred by a stirring device at a stirring speed of 200 rpm for 30 minutes until uniform, to obtain mixture three;

[0056] P2: 20 parts of water, 2 parts of hydroxyethyl cellulose, 30 parts of flame retardant, and 0.6 parts of cationic dispersant were stirred by a stirring device at a stirring speed of 200 rpm for 30 minutes to obtain a mixture IV;

[0057] P3: Add 82 parts of polysiloxane, 1 part of film-forming aid and mixture 4 into mixture 3 and continue mixing. The stirring speed is 200 rpm and the stirring time is 30 minutes to obtain the outer coating.

[0058] Example 3 A coating and a method for preparing the same

[0059] Colorless and transparent fire retardant coating, mainly composed of inner coating and outer coating, including:

[0060] The inner coating is mainly composed of the following raw materials in parts by weight: 50 parts of waterborne polypropylene resin, 70 parts of waterborne polyurethane resin, 100 parts of polysiloxane, 1.5 parts of film-forming aid, 30 parts of dimethyl sulfoxide, 5 parts of anionic dispersant, 6 parts of porous silica loaded nano silver antibacterial agent, and 8 parts of preservative;

[0061] The outer coating is mainly composed of the following raw materials in weight fractions: 50 parts of water-based polypropylene resin, 70 parts of water-based polyurethane resin, 100 parts of polysiloxane, 1.5 parts of film-forming aid, 30 parts of water, 4 parts of hydroxyethyl cellulose, 50 parts of flame retardant, and 1.75 parts of cationic dispersant;

[0062] In this embodiment, the film-forming aids of the inner layer coating and the outer layer coating are both selected from glycol butyl ether acetate, the anionic dispersant is sodium polymethacrylate, the cationic dispersant is amino-modified polysiloxane, the preservative of the inner layer coating is Dowicil 200, and the flame retardant of the outer layer coating is borax.

[0063] In this embodiment, the preparation method of the inner layer coating comprises the following steps:

[0064] S1: 50 parts of waterborne polypropylene resin and 70 parts of waterborne polyurethane resin were stirred by a stirring device at a stirring speed of 300 rpm for 60 minutes until the mixture was uniform, to obtain a mixture 1;

[0065] S2: 30 parts of dimethyl sulfoxide, 5 parts of anionic dispersant, 6 parts of porous silica-loaded nanosilver antibacterial agent, and 8 parts of preservative are placed in an ultrasonic device, and treated with ultrasound at an ultrasonic power of 800 W for 30 minutes to obtain a mixture II;

[0066] S3: Add 100 parts of polysiloxane, 1.5 parts of film-forming aid and mixture 2 into mixture 1, stir at a speed of 500 rpm, and stir for 80 minutes until uniform, to obtain the inner coating.

[0067] In this embodiment, the method for preparing the outer coating comprises the following steps:

[0068] P1: 50 parts of waterborne polypropylene resin and 70 parts of waterborne polyurethane resin were stirred by a stirring device at a stirring speed of 500 rpm for 80 minutes until uniform, to obtain mixture three;

[0069] P2: 30 parts of water, 4 parts of hydroxyethyl cellulose, 50 parts of flame retardant, and 1.75 parts of cationic dispersant were stirred by a stirring device at a stirring speed of 500 rpm for 80 minutes to obtain a mixture of four;

[0070] P3: Add 100 parts of polysiloxane, 1.5 parts of film-forming aid and mixture 4 into mixture 3 and continue mixing. The stirring speed is 500 rpm and the stirring time is 80 minutes to obtain the outer coating.

[0071] Comparative Example 1 A coating and a preparation method thereof

[0072] The formula and preparation method of Comparative Example 1 are basically the same as those of Example 1, except that the amount of the cationic dispersant used is different. In Comparative Example 1, the amount of the cationic dispersant used is 2.4 parts, which exceeds 35% of the amount of the anionic dispersant used.

[0073] Comparative Example 2 A coating and a preparation method thereof

[0074] The formula and preparation method of Comparative Example 2 are substantially the same as those of Example 1, except that: in Comparative Example 2, 24 parts of water are used as the solvent for the inner layer coating instead of dimethyl sulfoxide.

[0075] Experimental Example 1 Performance Test

[0076] Preparation of experimental samples: prepare 20 wood blocks made by the same process and divide them into 4 groups. Each group selects one of the coatings prepared in Examples 1-3, Comparative Example 1, and Comparative Example 2 for use. Spray the 4 wood blocks in this group. The outer wall of the wood block is first coated with an inner layer of coating and then with an outer layer of coating. The spraying method is that the inner layer of coating has a spraying thickness of about 15-20 microns, and it is dried for 10 minutes after spraying. Then, the outer layer of coating is sprayed with a spraying thickness of still 15-20 microns, and it is completely dried after spraying. In this experimental example, the drying time is 3 days, and 20 wood block samples are obtained, and the paint layers are all colorless and transparent.

[0077] Among the four groups of samples prepared, five wood blocks in each group were tested in one of the following ways: fire test, anti-corrosion test, adhesion test, and shedding test. The test results are shown in Table 1:

[0078] Table 1

[0079]

[0080] From Table 1 we can see that:

[0081] In terms of fire retardancy test, Examples 1-3 of the present invention are all B1 grade flame retardant materials. In Comparative Example 1, the improvement of the formula mainly lies in the amount of cationic dispersant in the outer coating. Although the amount of cationic dispersant is increased, the flame retardancy of Comparative Example 1 is not greatly changed. In Comparative Example 2, there is no improvement in the outer coating formula, and the main improvement is the selection of the inner coating solvent, which has little effect on the flame retardancy level.

[0082] In terms of corrosion resistance test, Examples 1-3 of the present invention all have strong corrosion resistance grades, while in Comparative Example 1, the improvement of the cationic dispersant of the outer coating did not change the corrosion resistance grade of the resulting coating, while in Comparative Example 2, the corrosion resistance grade was reduced. The inventors speculate that the reason for this phenomenon is that dimethyl sulfoxide is replaced by water, which to some extent affects the dispersion uniformity of the antibacterial agent and the preservative, resulting in a reduction in the corrosion resistance grade, but this effect is not particularly significant.

[0083] In terms of adhesion test, after cross-cutting with a grating knife, none of Examples 1-3 of the present invention fell off, reaching the level 0 standard, while both Comparative Examples 1 and 2 showed partial delamination and shedding. The inventors judged that the reason for the control of the amount of anionic dispersant and cationic dispersant in Comparative Example 1 was excessive charge neutralization, resulting in a decrease in the stability of the dispersion system and affecting the adhesion. In Comparative Example 2, the solvent of the inner layer coating was changed from dimethyl sulfoxide to , which reduced the close bonding between the inner layer coating and the outer layer coating, affecting the adhesion.

[0084] In the shedding test, after 10 cycles of hot and cold operation, Examples 1-3 of the present invention showed no cracking and no shedding, but Comparative Example 1 showed cracking, and Comparative Example 2 showed cracking and partial outer layer shedding. It is considered that the adjustment of the dosage ratio of the anionic dispersant and the cationic dispersant and the replacement of dimethyl sulfoxide with water affected the adhesion between the inner coating and the outer coating.

[0085] The above is a preferred embodiment of the present invention. For ordinary technicians in this technical field, making several improvements and modifications without departing from the principles of the present invention should also be regarded as within the protection scope of the present invention.

Claims

1. A colorless and transparent fire retardant coating, characterized in that: It is mainly composed of inner coating and outer coating, including: The inner coating is mainly composed of the following raw materials in parts by weight: 30-50 parts of waterborne polypropylene resin, 50-70 parts of waterborne polyurethane resin, 80-100 parts of polysiloxane, 1-1.5 parts of film-forming aid, 20-30 parts of dimethyl sulfoxide, 3-5 parts of anionic dispersant, 4-6 parts of porous silica loaded nano silver antibacterial agent, and 5-8 parts of preservative; The outer coating is mainly composed of the following raw materials in weight fractions: 30-50 parts of water-based polypropylene resin, 50-70 parts of water-based polyurethane resin, 80-100 parts of polysiloxane, 1-1.5 parts of film-forming aid, 20-30 parts of water, 2-4 parts of hydroxyethyl cellulose, 30-50 parts of flame retardant, and N parts of cationic dispersant, where N is 20-35% of the amount of anionic dispersant used; When in use, the outer wall of the object to be coated is first coated with the inner layer of coating and then with the outer layer of coating.

2. A colorless and transparent fire retardant coating according to claim 1, characterized in that: The film-forming aids of the inner layer coating and the outer layer coating are selected from one or more of dodecyl alcohol ester, dipropylene glycol butyl ether, diethylene glycol butyl ether, methyl isobutyl ketone, and glycol butyl ether acetate.

3. A colorless and transparent fire retardant coating according to claim 1, characterized in that: The anionic dispersant is one or more of polycarboxylates, sodium polyacrylate, polyphosphates, sulfonates, and polyether-modified polycarboxylates.

4. The colorless and transparent fire retardant coating according to claim 1, characterized in that: The cationic dispersant is one or more of polyquaternary ammonium salts, polyamines, polyamidoamines, polyethyleneimine and amino-modified polysiloxane.

5. The colorless and transparent fire retardant coating according to claim 1, characterized in that: The preservative of the inner coating is selected from one of isothiazolinone preservatives, benzisothiazolinone preservatives or iodopropynyl butyl carbamate preservatives.

6. The colorless and transparent fire retardant coating according to claim 1, characterized in that: The flame retardant of the outer coating is selected from one of phosphate flame retardants, borate flame retardants, organic phosphorus flame retardants or silane flame retardants.

7. The colorless and transparent fire retardant coating according to claim 1, characterized in that: The preparation method of the inner layer coating comprises the following steps: S1: 30-50 parts of waterborne polypropylene resin and 50-70 parts of waterborne polyurethane resin are uniformly stirred by a stirring device to obtain a mixture 1; S2: 20-30 parts of dimethyl sulfoxide, 3-5 parts of anionic dispersants, 4-6 parts of porous silica-loaded nanosilver antibacterial agents, and 5-8 parts of preservatives are placed in an ultrasonic device and treated with ultrasonic waves for 20-30 minutes to obtain a second mixture; S3: Add 80-100 parts of polysiloxane, 1-1.5 parts of film-forming aid and mixture 2 into mixture 1 and continue mixing until uniform, thereby obtaining the inner coating.

8. A colorless and transparent fire retardant coating according to claim 7, characterized in that: In step S1, the stirring speed is 200-300 rpm, and the stirring time is 40-60 min; in step S2, the ultrasonic power is 600-800 W; in step S3, the stirring speed is 200-500 rpm, and the stirring time is 40-80 min.

9. The colorless and transparent fire retardant coating according to claim 1, characterized in that: The preparation method of the outer coating comprises the following steps: P1: 30-50 parts of waterborne polypropylene resin and 50-70 parts of waterborne polyurethane resin are stirred evenly by a stirring device to obtain a mixture three; P2: 20-30 parts of water, 2-4 parts of hydroxyethyl cellulose, 30-50 parts of flame retardant, and N parts of cationic dispersant (N is 20-35% of the amount of anionic dispersant) are stirred uniformly by a stirring device to obtain a mixture IV; P3: Add 80-100 parts of polysiloxane, 1-1.5 parts of film-forming aid and mixture 4 into mixture 3 and continue mixing until uniform to obtain the outer coating.

10. The colorless and transparent fire retardant coating according to claim 9, characterized in that: The stirring speeds in steps P1, P2 and P3 are all 200-500 rpm, and the stirring is for 30-80 min.

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