A colorless and transparent fire-retardant coating

Abstract

This invention belongs to the field of fire-retardant coating technology, specifically relating to a colorless and transparent fire-retardant coating. The inner layer coating of this invention is mainly composed of the following raw materials in parts by weight: 30-50 parts water-based polypropylene resin, 50-70 parts water-based polyurethane resin, 80-100 parts polysiloxane, 1-1.5 parts film-forming aid, 20-30 parts dimethyl sulfoxide, 3-5 parts anionic dispersant, 4-6 parts porous silica-supported nano-silver antibacterial agent, and 5-8 parts preservative. The outer layer coating is mainly composed of the following raw materials in parts by weight: 30-50 parts water-based polypropylene resin, 50-70 parts water-based polyurethane resin, 80-100 parts polysiloxane, 1-1.5 parts film-forming aid, 20-30 parts water, 2-4 parts hydroxyethyl cellulose, 30-50 parts flame retardant, and N parts cationic dispersant, where N is 20-35% of the amount of anionic dispersant. This invention is fire-retardant and corrosion-resistant, with high adhesion between the inner and outer coatings.

Description

Technical Field

[0001] This invention belongs to the field of fire-retardant coating technology, specifically relating to a colorless and transparent fire-retardant coating. Background Technology

[0002] Clear coatings, also known as varnishes, are primarily used in applications where maintaining the natural color or gloss of the substrate is crucial, such as the protection and decoration of wood, glass, and metal surfaces. In the woodworking industry, the antibacterial, preservative, and flame-retardant properties of clear coatings are particularly important. In clear coating formulation research, the amount of antibacterial agents, preservatives, and flame retardants used is generally small in the overall formulation. During coating preparation, the effectiveness of these agents is often limited by factors such as stirring losses and dispersion uniformity.

[0003] Therefore, providing a coating that has good antibacterial and anti-corrosion effects on wood and excellent flame retardant properties is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide a colorless and transparent fire-retardant coating that overcomes the shortcomings of the aforementioned prior art. The coating consists of an inner layer and an outer layer. The inner layer adheres to the grain of the wood product and forms a protective film, providing antibacterial and anti-corrosion effects. The outer layer primarily functions as a flame retardant. This creates a layered protection system for the wood product, with the inner layer primarily preventing decay and the outer layer primarily providing fire resistance. This further extends the lifespan of the wood product. Moreover, the two layers are tightly bonded and do not easily fall off, and the fire-retardant effect of the bonded layer is equally excellent.

[0005] The technical solution of this invention is as follows:

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

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

[0008] The inner coating is sprayed onto the outer wall of the wood, providing excellent antibacterial and anti-corrosion properties. The anionic dispersant, combined with porous silica-supported nano-silver antibacterial agent, ensures uniform dispersion of the antibacterial agent throughout the coating system. This uniform dispersion is further stabilized by the solvent dimethyl sulfoxide. Furthermore, the combined effect of the anionic dispersant, porous silica-supported nano-silver antibacterial agent, and dimethyl sulfoxide provides excellent anti-settling properties, eliminating the need for additional anti-settling agents.

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

[0010] The main function of the outer coating is different from that of the inner coating, which is antibacterial and anti-corrosion. It acts outside the inner coating and mainly plays a role in fire prevention and flame retardancy. In the outer coating, although the amount of cationic dispersant is less than that of the inner coating, combined with the stabilizing and dispersing effect of hydroxyethyl cellulose, the flame retardant can be stably dispersed in the entire coating system, and there is no need to add an anti-settling agent.

[0011] When using, first apply the inner layer of coating to the outer wall of the item to be coated, then apply the outer layer of coating. The inner layer of coating should be sprayed to a thickness of about 15-20 micrometers. After spraying, let it dry for 5-10 minutes. Then, you can spray another layer of inner layer of coating, using the same method as the first layer. Alternatively, you can directly spray the outer layer of coating, with a thickness of 15-20 micrometers. After spraying, let it dry.

[0012] Because the inner and outer coatings are composed of different raw materials and have different functions, this invention has conducted in-depth research on tightly bonded coatings to prevent peeling due to unstable bonding between the inner and outer coatings. The solution is as follows:

[0013] First, the solvent dimethyl sulfoxide in the inner coating combines with the solvent in the outer coating. Dimethyl sulfoxide and water can form a stable mixture through dipole-dipole interactions and hydrogen bonding. Both are non-flammable raw materials, which improves 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 tightness of the bonding between the inner and outer coatings.

[0014] Secondly, some of the anionic surfactants in the inner coating interact with the cationic dispersants in the outer coating. Dispersants with different charges attract each other, forming a more stable adsorption bond layer, which improves the stability of the dispersion system. However, in order to prevent complete charge neutralization during the combination of anionic and cationic dispersants, which would lead to a decrease in the stability of the dispersion system and particle aggregation and sedimentation, the inventors conducted extensive research. They finally discovered that when the cationic dispersant in the outer coating is 20-35% of the amount of anionic dispersant, the dispersants can attract each other and form a stable adsorption bond without affecting the stability of the dispersion system. In the outer coating, although the amount of cationic molecular dispersant added is small, hydroxyethyl cellulose also plays a certain role in preventing particle aggregation and sedimentation and improving the suspension stability of the coating.

[0015] Through the above innovative design, the raw materials in the two coating layers are combined to effectively prevent the instability of the interlayer bonding. At the same time, the fire resistance of the outer layer of the entire coating system is greatly improved, and the antibacterial and anti-corrosion properties of the inner layer are greatly improved.

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

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

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

[0019] Preferably, the preservative in 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 ester flame retardants, borate flame retardants, organophosphorus flame retardants, or silane flame retardants.

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

[0022] S1: Mix 30-50 parts of waterborne polypropylene resin and 50-70 parts of waterborne polyurethane resin using a stirring device at a speed of 200-300 rpm for 40-60 minutes until homogeneous to obtain mixture one.

[0023] S2: Place 20-30 parts of dimethyl sulfoxide, 3-5 parts of anionic dispersant, 4-6 parts of porous silica-supported nano-silver antibacterial agent, and 5-8 parts of preservative in an ultrasonic device and treat with ultrasound at an ultrasonic power of 600-800W for 20-30 minutes to obtain mixture two;

[0024] S3: Add 80-100 parts of polysiloxane, 1-1.5 parts of film-forming aid and mixture two to mixture one, stir at 200-500 rpm for 40-80 minutes until uniform, and the inner coating is obtained.

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

[0026] P1: Mix 30-50 parts of waterborne polypropylene resin and 50-70 parts of waterborne polyurethane resin with a stirring device at a stirring speed of 200-500 rpm for 30-80 minutes until homogeneous to obtain mixture three.

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

[0028] P3: Add 80-100 parts of polysiloxane, 1-1.5 parts of film-forming aid and mixture four to mixture three and continue mixing. The stirring speed is 200-500 rpm and the mixture is stirred for 30-80 minutes to obtain the outer coating.

[0029] The beneficial effects of the above technical solutions are as follows:

[0030] This invention breaks away from the traditional approach of spraying coatings onto the outer surface of wood products. Based on the actual needs of protecting wood products, an inner layer of coating is first applied to the outer surface of the wood product. This inner layer of coating adheres to the wood grain and forms a protective film, providing antibacterial and anti-corrosion effects. Then, an outer layer of coating is applied, which primarily serves a flame-retardant function. This creates a layered protection system for the wood product, with the inner layer mainly preventing decay and the outer layer primarily providing fire resistance, thereby further extending the service life of the wood product.

[0031] To prevent separation and detachment of coatings with different components during bonding, in-depth research was conducted on achieving tight bonding. Firstly, dimethyl sulfoxide (DMSO) in the inner coating combines with water and hydroxyethyl cellulose (HFC) in the outer coating. DMSO and water form a stable mixture through dipole-dipole interactions and hydrogen bonding. Both are non-flammable materials, improving the fire resistance of the bonding layer. Furthermore, the introduction of hydroxyethyl cellulose, a compound with multiple hydrogen bond donors and acceptors, increases the interaction between water and DMSO, thereby enhancing the tight bonding between the inner and outer coatings. Secondly, a portion of the anionic surfactant in the inner coating interacts with the cationic dispersant in the outer coating. Dispersants with different charges attract each other, forming a more stable adsorption bonding layer and improving the stability of the dispersion system. Through these innovative designs, the synergistic effect of the raw materials in the two coating layers effectively prevents unstable bonding between coatings, significantly improving the fire resistance of the outer layer and the antibacterial and anti-corrosion properties of the inner layer of the entire coating system. Detailed Implementation

[0032] Example 1: A coating and its preparation method

[0033] Colorless and transparent fire-retardant coating, mainly composed of an inner layer coating and an outer layer coating, wherein:

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

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

[0036] In this embodiment, the film-forming aid for both the inner and outer coatings is dipropylene glycol butyl ether, the anionic dispersant is sodium polyacrylate, the cationic dispersant is polyquaternium-10, the preservative for the inner coating is Kathon, and the flame retardant for the outer coating is triphenyl phosphate.

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

[0038] S1: Mix 42 parts of waterborne polypropylene resin and 60 parts of waterborne polyurethane resin using a stirring device at a speed of 260 rpm for 50 minutes to obtain mixture one.

[0039] S2: Place 24 parts of dimethyl sulfoxide, 4 parts of anionic dispersant, 5 parts of porous silica-supported nano-silver antibacterial agent, and 7 parts of preservative into an ultrasonic device and treat with ultrasound at an ultrasonic power of 700W for 25 minutes to obtain mixture two.

[0040] S3: Add 94 parts of polysiloxane, 1.3 parts of film-forming aid and mixture two to mixture one, stir at 350 rpm for 60 minutes to obtain the inner coating.

[0041] In this embodiment, the preparation method of the outer coating includes the following steps:

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

[0043] P2: Mix 24 parts water, 3 parts hydroxyethyl cellulose, 40 parts flame retardant, and 1.2 parts cationic dispersant using a stirring device at a speed of 350 rpm for 55 minutes to obtain mixture four;

[0044] P3: Add 94 parts of polysiloxane, 1.3 parts of film-forming aid and mixture four to mixture three and continue mixing. Stir at 350 rpm for 55 minutes to obtain the outer coating.

[0045] Example 2: A coating and its preparation method

[0046] Colorless and transparent fire-retardant coating, mainly composed of an inner layer coating and an outer layer coating, wherein:

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

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

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

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

[0051] S1: Mix 30 parts of waterborne polypropylene resin and 50 parts of waterborne polyurethane resin using a stirring device at a speed of 200 rpm for 40 minutes until homogeneous to obtain mixture one.

[0052] S2: Place 20 parts of dimethyl sulfoxide, 3 parts of anionic dispersant, 4 parts of porous silica-supported nano-silver antibacterial agent, and 5 parts of preservative into an ultrasonic device and treat with ultrasound at an ultrasonic power of 600W for 20 minutes to obtain mixture two.

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

[0054] In this embodiment, the preparation method of the outer coating includes the following steps:

[0055] P1: Mix 30 parts of waterborne polypropylene resin and 50 parts of waterborne polyurethane resin with a stirring device at a stirring speed of 200 rpm for 30 minutes until homogeneous to obtain mixture three.

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

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

[0058] Example 3: A coating and its preparation method

[0059] Colorless and transparent fire-retardant coating, mainly composed of an inner layer coating and an outer layer coating, wherein:

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

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

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

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

[0064] S1: Mix 50 parts of waterborne polypropylene resin and 70 parts of waterborne polyurethane resin using a stirring device at a speed of 300 rpm for 60 minutes until homogeneous to obtain mixture one.

[0065] S2: Place 30 parts of dimethyl sulfoxide, 5 parts of anionic dispersant, 6 parts of porous silica-supported nano-silver antibacterial agent, and 8 parts of preservative into an ultrasonic device and treat with ultrasound at an ultrasonic power of 800W for 30 minutes to obtain mixture two.

[0066] S3: Add 100 parts of polysiloxane, 1.5 parts of film-forming aid and mixture two to mixture one, stir at 500 rpm for 80 minutes until uniform, and the inner coating is obtained.

[0067] In this embodiment, the preparation method of the outer coating includes the following steps:

[0068] P1: Mix 50 parts of waterborne polypropylene resin and 70 parts of waterborne polyurethane resin with a stirring device at a stirring speed of 500 rpm for 80 minutes until homogeneous to obtain mixture three.

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

[0070] P3: Add 100 parts of polysiloxane, 1.5 parts of film-forming aid and mixture four to mixture three and continue mixing. Stir at 500 rpm for 80 minutes to obtain the outer coating.

[0071] Comparative Example 1: A coating and its preparation method

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

[0073] Comparative Example 2: A coating and its preparation method

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

[0075] Experiment Example 1 Performance Test

[0076] Sample preparation: 20 wood blocks prepared using the same process were prepared and divided into 4 groups. For each group, one type of coating was selected from the coatings prepared in Examples 1-3, Comparative Example 1, and Comparative Example 2. The coatings were sprayed onto the 4 wood blocks in the group. The inner coating was applied to the outer wall of the wood block first, followed by the outer coating. The inner coating was applied to a thickness of about 15-20 micrometers. After drying for 10 minutes, the outer coating was applied, again to a thickness of 15-20 micrometers. The coatings were allowed to dry completely after drying. In this experiment, the drying time was 3 days, resulting in 20 wood block samples. All the coatings were colorless and transparent.

[0077] Of the four groups of samples obtained, five wooden blocks in each group were tested using one of the following methods: fire resistance test, corrosion resistance test, adhesion test, and detachment test. The test results are shown in Table 1.

[0078] Table 1

[0079]

[0080] As can be seen from Table 1:

[0081] Regarding fire resistance testing, Examples 1-3 of this invention are all B1-grade flame-retardant materials. In Comparative Example 1, the main improvement in the formulation lies in the amount of cationic dispersant in the outer coating. Although the amount of cationic dispersant increased, it did not significantly change the flame retardancy of Comparative Example 1. In Comparative Example 2, the outer coating formulation was not improved, and the main improvement was in the selection of the solvent for the inner coating. This improvement had little impact on the flame retardancy rating.

[0082] Regarding corrosion resistance testing, Examples 1-3 of this invention all achieved a high corrosion resistance rating. However, in Comparative Example 1, the improvement of the cationic dispersant in the outer coating did not change the corrosion resistance rating of the resulting coating. In Comparative Example 2, the corrosion resistance rating decreased. The inventors speculate that this phenomenon is due to the replacement of dimethyl sulfoxide with water, which to some extent affected the dispersion uniformity of the antibacterial agent and the preservative, resulting in a decrease in the corrosion resistance rating. However, this effect is not particularly significant.

[0083] Regarding adhesion testing, after cross-cutting with a cross-cutting tool, none of Examples 1-3 of this invention showed any peeling, achieving a level 0 standard. However, Comparative Examples 1 and 2 showed localized delamination and peeling. The inventors determined that the issue with the dosage of anionic and cationic dispersants in Comparative Example 1 resulted in excessive charge neutralization, leading to decreased stability of the dispersion system and affecting adhesion. In Comparative Example 2, the solvent for the inner coating was easily replaced with dimethyl sulfoxide, which reduced the tightness of the bond between the inner and outer coatings, thus affecting adhesion.

[0084] In terms of peeling test, after 10 cycles of hot and cold heating, there was no cracking or peeling in Examples 1-3 of the present invention, but cracking occurred in Comparative Example 1 and local peeling of the outer layer occurred in Comparative Example 2. The reason is considered to be that the adjustment of the ratio of anionic dispersant and cationic dispersant and the operation of replacing dimethyl sulfoxide with water affected the adhesion between the inner coating and the outer coating.

[0085] The above description is a preferred embodiment of the present invention. For those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A colorless and transparent fire-retardant coating, characterized in that: It mainly consists of an inner coating and an outer coating, wherein: The inner coating is composed of the following raw materials in parts by weight: 30-50 parts waterborne polypropylene resin, 50-70 parts waterborne polyurethane resin, 80-100 parts polysiloxane, 1-1.5 parts film-forming aid, 20-30 parts dimethyl sulfoxide, 3-5 parts anionic dispersant, 4-6 parts porous silica-supported nano-silver antibacterial agent, and 5-8 parts preservative. The anionic dispersant is one or more of polycarboxylates, polyphosphates, sulfonates, and polyether-modified polycarboxylates. The outer coating is composed of the following raw materials in the indicated weight fractions: 30-50 parts waterborne polypropylene resin, 50-70 parts waterborne polyurethane resin, 80-100 parts polysiloxane, 1-1.5 parts film-forming aid, 20-30 parts water, 2-4 parts hydroxyethyl cellulose, 30-50 parts flame retardant, and N parts cationic dispersant, where N is 20-35% of the amount of anionic dispersant, and the cationic dispersant is a polyquaternary ammonium salt. When using this coating, first apply the inner layer of paint to the outer wall of the item to be coated, and then apply the outer layer of paint.

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

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

4. 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 the following: phosphate ester flame retardants, borate flame retardants, and organophosphorus flame retardants.

5. The colorless and transparent fire-retardant coating according to claim 1, characterized in that: The preparation method of the inner coating includes the following steps: S1: Mix 30-50 parts of waterborne polypropylene resin and 50-70 parts of waterborne polyurethane resin evenly using a mixing device to obtain mixture one; S2: Place 20-30 parts of dimethyl sulfoxide, 3-5 parts of anionic dispersant, 4-6 parts of porous silica-supported nano-silver antibacterial agent, and 5-8 parts of preservative in an ultrasonic device and treat with ultrasound for 20-30 minutes to obtain mixture two. S3: Add 80-100 parts of polysiloxane, 1-1.5 parts of film-forming aid and mixture two to mixture one and continue mixing until uniform to obtain the inner coating.

6. The colorless and transparent fire-retardant coating according to claim 5, 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.

7. The colorless and transparent fire-retardant coating according to claim 1, characterized in that: The preparation method of the outer coating includes the following steps: P1: Mix 30-50 parts of waterborne polypropylene resin and 50-70 parts of waterborne polyurethane resin evenly using a mixing device to obtain mixture three; P2: Mix 20-30 parts water, 2-4 parts hydroxyethyl cellulose, 30-50 parts flame retardant, and N parts cationic dispersant using a stirring device to obtain mixture four; P3: Add 80-100 parts of polysiloxane, 1-1.5 parts of film-forming aid and mixture four to mixture three and continue mixing until uniform to obtain the outer coating.

8. The colorless and transparent fire-retardant coating according to claim 7, characterized in that: The stirring speed for steps P1, P2 and P3 is 200-500 rpm, and the stirring time is 30-80 min.

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