High-viscosity low-expansion fireproof coating as well as preparation method and application thereof

Abstract

The invention discloses a high-viscosity low-expansion fireproof coating as well as a preparation method and application thereof. The high-viscosity low-expansion fireproof coating comprises the following components: an epoxy resin prefabricated liquid, a flame retardant and an inorganic filler, wherein the inorganic filler is glass powder or a mixture of glass powder and light filler; the mass ratio of the flame retardant to the epoxy resin prefabricated liquid is (15-20): (85-80); the mass of the inorganic filler accounts for more than 50% of the sum of the mass of all the components. Through the innovative formula and process, the excellent fireproof performance is maintained, and meanwhile the bonding strength and stability of the coating are remarkably improved. Besides, the coating has lower expansion rate, a formed expansion layer is stable in structure, flame propagation can be effectively prevented, and a high-performance fireproof solution is provided for related industries.

Description

Technical Field

[0001] The present invention belongs to the technical field of fire retardant coatings, and in particular relates to a high-viscosity, low-expansion fire retardant coating and a preparation method and application thereof. Background Art

[0002] Fire-retardant coatings are widely used in buildings and industrial facilities. Their primary function is to slow the spread of fire, buying valuable time for evacuation and firefighting. However, traditional fire-retardant coatings have numerous limitations, such as insufficient adhesion, especially on complex substrates or in harsh environments, which can lead to coating detachment and cracking. Furthermore, some fire-retardant coatings expand excessively when heated, creating an unstable expansion layer structure that compromises their fire-resistant effectiveness.

[0003] As emerging fire protection applications demand increased comprehensive material performance (e.g., automotive battery fire protection, drone fire protection, fire truck protection, and automotive chip packaging, requiring both high adhesion and low expansion), traditional fire protection systems face new challenges. In applications subject to complex working conditions such as mechanical vibration and high mobility, inorganic fire retardant coatings such as gypsum and cement-based coatings, as well as organic systems such as epoxy resins and acrylic emulsions, have demonstrated performance limitations. For example, patent publication number CN111019503A, "An Aerogel Thermal Insulation, Fireproof, and Waterproof Intumescent Fire Retardant Coating and Preparation Method thereof," demonstrates that the adhesion of the water-based acrylic resin-based fire retardant coating is only 0.2 MPa, indicating that the interfacial bonding strength of existing coatings still has significant room for improvement.

[0004] In recent years, the industry has begun to explore emerging high-adhesion fire-retardant coatings. For example, in the patent "A high-temperature resistant fire-retardant coating powder and its preparation method" with publication number CN118772744A, oily epoxy resin is directly used as the filler matrix, and the prepared fire-retardant coating has an adhesion of up to 53 MPa. However, the patent does not specify the volume expansion rate of this coating, and its composition and process are relatively complicated. In addition, the patent "Fire-retardant coating for new energy vehicle power battery pack and its preparation method" with publication number CN119060609A introduces a fire-retardant coating specially designed for new energy power batteries, which also uses oily epoxy resin. However, the patent does not give specific bonding performance values, and the coating is an intumescent fire-retardant coating.

[0005] In summary, it is particularly important to develop a fire retardant coating with high adhesion and low expansion properties. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a high-viscosity, low-expansion fire-retardant coating, its preparation method, and its application, aiming to address the shortcomings of existing fire-retardant coatings in terms of adhesion and expansion performance. Through innovative formulations and processes, the present invention significantly improves the coating's bonding strength and stability while maintaining excellent fire-retardant performance. Furthermore, the coating exhibits a low expansion ratio, resulting in a stable expansion layer structure that effectively prevents flame propagation, providing a high-performance fire protection solution for related industries.

[0007] The purpose of the present invention is achieved through the following technical solutions: A high-viscosity, low-expansion fire-retardant coating, the components of which include epoxy resin prefabricated liquid, flame retardant and inorganic filler; Wherein, the inorganic filler is glass powder or a mixture of glass powder and lightweight filler; The mass ratio of the flame retardant to the epoxy resin prefabricated liquid is 15-20:85-80; the mass of the inorganic filler accounts for more than 50% of the sum of the masses of all components.

[0008] Preferably, when the inorganic filler is a mixture of glass powder and lightweight filler, the mass fraction of the glass powder accounts for more than 65% of the total mass of the filler system.

[0009] Preferably, the epoxy resin prefabricated liquid comprises the following components in parts by mass: 65-70 parts of epoxy resin, 20-25 parts of curing agent, 5-8 parts of diluent and 1-2 parts of accelerator.

[0010] Preferably, the epoxy resin is a bisphenol A epoxy resin with an average epoxy value of 0.50-0.56 mol / 100g.

[0011] Preferably, the curing agent is at least one of polyetheramine D230, polyamide 650, isophorone diamine and N,N'-dicyclohexylmethane diamine.

[0012] Preferably, the diluent is at least one of propylene oxide phenyl ether, benzyl glycidyl ether 692 and phenyl glycidyl ether 690.

[0013] Preferably, the accelerator is at least one of 2,4,6-tris(dimethylaminomethyl)phenol, benzyldimethylamine and benzyl alcohol.

[0014] Preferably, the flame retardant is at least one of bisphenol A-bis(diphenyl phosphate), dimethyl methyl phosphate and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

[0015] Preferably, the glass powder is at least one of soda-lime-silica glass and borosilicate glass, and the glass powder D50 is ≤1 mm.

[0016] Preferably, the lightweight filler is at least one of expanded perlite, expanded vermiculite, glass microspheres, fly ash microspheres and SiO2 aerogel.

[0017] The preparation method of the high-viscosity, low-expansion fire-retardant coating comprises the following steps: uniformly mixing the epoxy resin prefabricated liquid, the flame retardant and the inorganic filler according to the component ratio.

[0018] Preferably, the inorganic filler is dried at 80-120°C for at least 12 hours before use. Because this coating system is based on a high-molecular-weight epoxy resin, moisture carried by the raw materials can reduce the resin-filler interface strength, thereby weakening the coating adhesion. Therefore, air drying at 80-120°C for at least 12 hours can ensure sufficient moisture volatilization while limiting the impact of thermal effects on the raw material surface functional groups.

[0019] Preferably, the epoxy resin preformed liquid, flame retardant and inorganic filler are mixed uniformly by stirring the mixture of the epoxy resin preformed liquid, flame retardant and inorganic filler at a stirring rate of 500-2000 rpm, with a single stirring time of ≤2 min; and maintaining the system temperature ≤60°C during the stirring process.

[0020] Since the coating system becomes more viscous after adding inorganic fillers, controlling the appropriate stirring speed not only helps to evenly mix the components but also avoids damage. In addition, the stirring temperature should be controlled within 60°C to prevent the curing speed from being too fast, which will affect the subsequent coating operation.

[0021] When preparing the epoxy resin preform, if the initial viscosity of the epoxy resin is too thick and difficult to weigh, you can choose to preheat it at 40-50°C for several hours. However, it should be noted that the temperature should not be too high, as it will affect the curing speed and shorten the curing time.

[0022] The above-mentioned high-viscosity, low-expansion fire-retardant coating is used in fire protection of batteries, drones, fire trucks and vehicle-mounted chips.

[0023] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention uses epoxy resin with high adhesion as the liquid matrix, which can not only form a continuous, dense and high-strength paint film during the curing process, effectively isolate the air and block the spread of fire, but also has excellent chemical corrosion resistance and weather resistance.

[0024] (2) The present invention uses glass powder as a key fireproofing component. After being continuously burned by a high-temperature flame, this component can form a non-combustible liquid phase and quickly spread into a continuous liquid film on the surface exposed to fire, effectively blocking oxygen from entering the interior, thereby achieving flame retardancy and flame isolation. In addition, according to the temperature range required for actual fire protection, glass powder with a corresponding melting temperature can be selected to improve the targetedness and adaptability of fireproofing performance.

[0025] (3) The present invention uses inorganic fillers, which can form a liquid phase in the surface glass to achieve a fire-isolating effect while further slowing down the transfer of heat to the interior of the material, thereby improving the thermal insulation performance of the fireproof material.

[0026] (4) The flame retardant used in the present invention is a non-intumescent flame retardant with high flame retardancy, good high-temperature stability, low volatility, low toxicity, and biodegradability. This flame retardant can be evenly mixed with epoxy resin to further enhance the material's fire resistance and become one of the key components in achieving low-intumescence properties in fire-retardant coatings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a bar graph of the shear strength of the high-viscosity, low-expansion fire-retardant coatings prepared in Examples 1 to 3 and Comparative Example 1.

[0028] Figure 2 The graph is a graph showing the change of the back-fired surface temperature of the samples of Examples 1 to 3 and Comparative Examples 2 to 3 over time.

[0029] Figure 3 These are photos of the samples of Examples 1-3 and Comparative Examples 2-3 after the fire performance test. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0031] In the following examples and comparative examples, the epoxy resin is epoxy resin E51, the curing agent is polyetheramine D230, the diluent is propylene oxide phenyl ether, the accelerator is 2,4,6-tris(dimethylaminomethyl)phenol, and the flame retardant is bisphenol A-bis(diphenyl phosphate).

[0032] Example 1 A high-viscosity, low-expansion fire-retardant coating, comprising, by mass, 42 parts of epoxy resin prefabricated liquid, 8 parts of flame retardant, and 50 parts of inorganic filler; Wherein, the inorganic filler is glass powder, which is dried in a blast drying oven at 100°C for 12 hours before use; The components of the epoxy resin prefabricated liquid are as follows: 68 parts of epoxy resin, 23 parts of curing agent, 7 parts of diluent and 2 parts of accelerator; A method for preparing a high-viscosity, low-expansion fire-retardant coating, comprising the following steps: (1) According to the above ratio, epoxy resin, curing agent, diluent and accelerator are placed in a mixer, and stirred at a speed of 500 r / min for 2 min under the condition that the stirring temperature does not exceed 60°C. After stirring evenly, an epoxy resin prefabricated liquid is obtained; (2) Add the epoxy resin preform liquid, flame retardant, and inorganic filler into a mixer according to the above ratio, and stir at a speed of 2000 r / min for 2 minutes under the condition that the stirring temperature does not exceed 60°C. After the stirring is completed, observe the mixing effect. If it is found that the materials are not fully mixed, repeat the above stirring steps until a uniform mixture is obtained, thereby obtaining the high-viscosity low-expansion fire retardant coating.

[0033] Example 2 A high-viscosity, low-expansion fire-retardant coating, comprising, by weight, 24 parts of epoxy resin prefabricated liquid, 5 parts of flame retardant, and 71 parts of inorganic filler; The inorganic filler comprises 67 parts of glass powder and 4 parts of expanded perlite; the inorganic filler is dried in a blast drying oven at 100° C. for 12 hours before use; The components of the epoxy resin prefabricated liquid are as follows: 68 parts of epoxy resin, 23 parts of curing agent, 7 parts of diluent and 2 parts of accelerator; The preparation method of the high-viscosity, low-expansion fire-retardant coating described in Example 2 is the same as that in Example 1.

[0034] Example 3 A high-viscosity, low-expansion fire-retardant coating, compared with Example 2, the only difference is that the mass fraction of glass powder is reduced to 65 parts, and the mass fraction of expanded perlite is increased to 6 parts.

[0035] Comparative Example 1 A high-viscosity, low-expansion fire-retardant coating, compared with Example 1, the only difference is that the epoxy resin pre-prepared liquid is replaced by an acrylic resin emulsion of equal quality, the acrylic resin emulsion is purchased from Shandong Huling New Materials Co., Ltd., and the product model is BA-201.

[0036] Comparative Example 2 A high-viscosity, low-expansion fire-retardant coating, compared with Example 1, the only difference is that the mass parts of the epoxy resin prefabricated liquid are 53 parts, the flame retardant is 10 parts, and the glass powder is 37 parts, that is, the mass of the glass powder accounts for 37% of the total mass of all components.

[0037] Comparative Example 3 A high-viscosity, low-expansion fire-retardant coating, differing from Example 2 only in that the epoxy resin preform liquid is 23 parts by weight, the flame retardant is 4 parts by weight, and the inorganic filler is 73 parts by weight; the inorganic filler comprises 63 parts by weight of glass powder and 10 parts by weight of expanded perlite. Thus, the mass of the glass powder accounts for 63% of the total mass of all components.

[0038] According to GB / T 7124-2008 "Determination of tensile shear strength of adhesives (rigid material to rigid material)", the shear strength of the high-viscosity low-expansion fire retardant coatings prepared in Examples 1 to 3 and Comparative Example 1 was measured to characterize their interfacial bonding performance. The test results are as follows: Figure 1 Reference Figure 1 We can see that the shear strengths of Examples 1-3 all exceed 15 MPa, consistent with the high viscosity characteristic. In Comparative Example 1, after replacing the epoxy resin matrix with an acrylic emulsion system, the shear strength of the resulting material is less than 1 MPa, which is difficult to meet the requirements for good bonding properties of fire retardant coatings.

[0039] The high-viscosity, low-expansion fire-retardant coatings prepared in Examples 1-3 and Comparative Examples 2-3 were subjected to an alcohol torch flame fireproofing performance test. The specific steps are as follows: After curing, the fire-retardant coatings described in Examples 1-3 and Comparative Examples 2-3 had a diameter of 80 mm. These coatings were then processed using a grinder into a fireproof material with a thickness of 15 mm. The materials were dried and then used for later use. The distance between the alcohol torch nozzle and the sample's exposed surface was adjusted to 100 mm. The alcohol torch was lit, with the flame aligned vertically with the exposed surface of the test sample, and the flame was continuously burned for 30 minutes. During the test, a dual-laser infrared thermometer (DT-833C, Shenzhen Huashengchang Technology Industry Co., Ltd.) was used to collect back-exposed surface temperature data. After the test, photographs of each substrate were taken to evaluate its fireproofing and heat-insulating effects and structural integrity.

[0040] Figure 2 The temperature of the back-fired surface of the samples of Examples 1 to 3 and Comparative Examples 2 to 3 changes with time. Figure 2 It can be seen that in the 10-minute flame test, the back-fire surface temperature of Comparative Examples 2 and 3 is close to 250°C, while the back-fire surface temperature of Examples 1 to 3 is always lower than 230°C, especially the back-fire surface temperature of Examples 2 to 3 is only 200°C, which is about 50°C lower than that of Comparative Examples 2 to 3.

[0041] Figure 3 The following are photos of samples of Examples 1 to 3 and Comparative Examples 2 to 3 after fire performance testing, where A corresponds to Example 1, B corresponds to Example 2, C corresponds to Example 3, D corresponds to Comparative Example 2, and E corresponds to Comparative Example 3; the illustration in the upper right corner of each figure is a stereogram of the sample. Figure 3We can see that after the alcohol burner test, the samples of Examples 1-3 remained intact, with minimal expansion. A distinct white vitrified layer formed on the exposed surface, effectively isolating the flame. With the addition of inorganic fillers (Examples 2 and 3), the degree of pyrolysis of organic matter at high temperatures was significantly reduced. In contrast, Comparative Example 2, due to its low glass powder content (37%), exhibited significant expansion and bulging during the test. In Comparative Example 3, due to the partial replacement of the glass powder with inorganic fillers, the glass powder content was reduced to 63%, resulting in significant cracking and delamination of the white glass layer formed after the test. This comprehensive comparison shows that Examples 1-3 not only exhibit excellent fire resistance but also a lower expansion rate, effectively meeting both requirements.

[0042] The specific embodiments of the present invention described above do not limit the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A high-viscosity, low-expansion fire-retardant coating, characterized in that: Its components include epoxy resin prefabricated liquid, flame retardant and inorganic filler; Wherein, the inorganic filler is glass powder or a mixture of glass powder and lightweight filler; The mass ratio of the flame retardant to the epoxy resin prefabricated liquid is 15-20:85-80; the mass of the inorganic filler accounts for more than 50% of the sum of the masses of all components.

2. The high-viscosity, low-expansion fire-retardant coating according to claim 1, characterized in that: When the inorganic filler is a mixture of glass powder and lightweight filler, the mass fraction of the glass powder accounts for more than 65% of the total mass of the filler system.

3. The high-viscosity, low-expansion fire-retardant coating according to claim 1 or 2, characterized in that: The epoxy resin prefabricated liquid comprises the following components in parts by mass: 65-70 parts of epoxy resin, 20-25 parts of curing agent, 5-8 parts of diluent and 1-2 parts of accelerator.

4. The high-viscosity, low-expansion fire-retardant coating according to claim 3, characterized in that: The epoxy resin is a bisphenol A epoxy resin with an average epoxy value of 0.50-0.56 mol / 100g; The curing agent is at least one of polyetheramine D230, polyamide 650, isophorone diamine and N,N'-dicyclohexylmethane diamine.

5. The high-viscosity, low-expansion fire-retardant coating according to claim 3, characterized in that: The diluent is at least one of propylene oxide phenyl ether, benzyl glycidyl ether 692 and phenyl glycidyl ether 690; The accelerator is at least one of 2,4,6-tris(dimethylaminomethyl)phenol, benzyldimethylamine and benzyl alcohol.

6. The high-viscosity, low-expansion fire-retardant coating according to claim 1, characterized in that: The flame retardant is at least one of bisphenol A-bis(diphenyl phosphate), dimethyl methyl phosphate and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide; The glass powder is at least one of soda-lime silicate glass and high borosilicate glass, and the glass powder D50 is ≤ 1 mm; The lightweight filler is at least one of expanded perlite, expanded vermiculite, glass microspheres, fly ash microspheres and SiO2 aerogel.

7. The method for preparing the high-viscosity, low-expansion fire-retardant coating according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: uniformly mixing epoxy resin prefabricated liquid, flame retardant and inorganic filler according to component proportions.

8. The method for preparing the high-viscosity, low-expansion fire-retardant coating according to claim 7, characterized in that: The inorganic filler is dried at 80-120° C. for at least 12 hours before use.

9. The method for preparing the high-viscosity, low-expansion fire-retardant coating according to claim 7, characterized in that: The epoxy resin preformed liquid, the flame retardant and the inorganic filler are uniformly mixed by stirring the mixture of the epoxy resin preformed liquid, the flame retardant and the inorganic filler at a stirring rate of 500 to 2000 rpm, with a single stirring time of ≤2 min; and maintaining the system temperature ≤60°C during the stirring process.

10. Use of the high-viscosity, low-expansion fire-retardant coating according to any one of claims 1 to 6 in fire protection of batteries, drones, fire trucks and on-board chips.

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