Aqueous nanocable fireproof coating and preparation method thereof

Abstract

This invention relates to the field of fire-retardant coating technology, and in particular to a water-based nano-cable fire-retardant coating and its preparation method. The fire-retardant coating comprises: 45-55 parts polyurethane emulsion, 12-18 parts nano-flame-retardant filler, 10-13 parts ammonium polyphosphate, 7-10 parts melamine, 5-8 parts charring agent, 5-8 parts foaming agent, 4-8 parts additives, and 20-40 parts water. The components of the fire-retardant coating provided by this invention work synergistically to form a dense, high-strength, heat-insulating char layer upon heating, exhibiting excellent flame-retardant properties and good application properties, making it suitable for fire protection of cables in power plants, buildings, and other similar settings.

Description

Technical Field

[0001] This invention relates to the field of fire-retardant coating technology, and in particular to a water-based nano-cable fire-retardant coating and its preparation method. Background Technology

[0002] Electric wires and cables are core wire products used to transmit electrical (magnetic) energy, transmit information, and realize electromagnetic energy conversion. They play an irreplaceable fundamental role in power transmission, communication networking, industrial production, and civil construction. With the continuous acceleration of urbanization and industrialization in my country, and the rapid rise of emerging industries such as new energy and new infrastructure, the market application scale of electric wires and cables continues to expand, and the application scenarios are becoming increasingly complex and diverse. The industry has put forward more stringent requirements for the safety protection performance of electric wires and cables, especially their fire resistance and flame retardant performance.

[0003] Fire-retardant coatings for cables are fire-resistant protective materials specifically designed for wires and cables. When exposed to high temperatures and open flames, the coating rapidly forms a uniform and dense sponge-like foam insulation layer, effectively inhibiting and blocking the spread of flames, thus protecting the cables. However, current fire-retardant coatings for cables have the following drawbacks: Most mainstream fire-retardant coatings are traditional organic intumescent coatings, which are not only highly toxic during production and use but also easily cause environmental pollution. Even water-based fire-retardant coatings typically use a single charring agent in their intumescent flame-retardant system, making it difficult to form a continuous and dense intumescent char layer after exposure to fire, thus failing to provide long-term heat transfer protection. Furthermore, existing water-based fire-retardant coatings also suffer from poor application performance, easily exhibiting defects such as brush marks, runs, and edge shrinkage during application. These defects not only affect the smoothness of the appearance but also damage the integrity of the coating, reducing the overall fire-retardant effect.

[0004] Therefore, there is an urgent need for a fire-retardant coating for cables that combines excellent flame-retardant properties and construction performance, which has become a pressing technical problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a water-based nano-fireproof cable coating and its preparation method, so as to overcome the shortcomings of the above-mentioned cable fireproof coatings that cannot simultaneously achieve both flame retardancy and construction performance.

[0006] To achieve the above objectives, the present invention provides a water-based nano-cable fire-retardant coating, comprising the following raw materials in parts by weight: 45-55 parts polyurethane emulsion, 12-18 parts nano flame retardant filler, 10-13 parts ammonium polyphosphate, 7-10 parts melamine, 5-8 parts charring agent, 5-8 parts foaming agent, 4-8 parts additives, and 20-40 parts water. The nano-flame retardant filler is a silane-modified nano-filler, which is aluminum hydroxide, magnesium hydroxide, and zinc borate.

[0007] The modification process includes: placing the nanofiller in an aqueous solution of a silane coupling agent and performing silane modification at a temperature of 50-70°C for 20-40 minutes to obtain silane-modified nanofiller. The aqueous solution of the silane coupling agent is a 5%-10% KH550 aqueous solution, and KH550 accounts for 3%-5% of the total mass of the nanofiller.

[0008] In this invention, the water-based nano-cable fireproof coating preferably comprises the following raw materials in parts by weight: 48-52 parts of polyurethane emulsion, 14-16 parts of nano flame-retardant filler, 11-12 parts of ammonium polyphosphate, 8-9 parts of melamine, 6-7 parts of charring agent, 6-7 parts of foaming agent, 5-7 parts of additives, and 25-35 parts of water.

[0009] In this invention, the particle size of aluminum hydroxide, magnesium hydroxide, and zinc borate is independently 10-100 nm; the mass ratio of aluminum hydroxide, magnesium hydroxide, and zinc borate is preferably 2-3:1:1.

[0010] In this invention, the char-forming agent preferably includes pentaerythritol and dipentaerythritol, and the mass ratio of pentaerythritol to dipentaerythritol is preferably 1-2:1, more preferably 1.5:1.

[0011] Pentaerythritol reacts rapidly with ammonium polyphosphate upon contact with fire to form an initial char layer, quickly blocking the initial spread of the flame. Dipentaerythritol exhibits excellent thermal stability and a higher char formation rate, maintaining a dense char layer structure at high temperatures and preventing cracking and detachment. The combination of these two components ensures both rapid char formation and sealing in the initial stage of the flame, while also providing long-term thermal insulation protection during the high-temperature phase, resulting in a denser expanded char layer and significantly improving the overall fire resistance limit of the coating.

[0012] In this invention, the foaming agent is preferably urea-formaldehyde resin. When heated, urea-formaldehyde resin continuously releases inert gases such as nitrogen, forming a phosphorus-nitrogen synergistic flame-retardant system with ammonium polyphosphate and melamine, further enhancing the flame-suppressing effect and extending the fire resistance limit of the coating. Simultaneously, urea-formaldehyde resin has good compatibility with polyurethane emulsion, preventing delamination and agglomeration, thus ensuring the coating's workability.

[0013] In this invention, the additives preferably include dispersants, leveling agents, and anti-settling agents; the mass ratio of the dispersant, leveling agent, and anti-settling agent is preferably 1-2:1-2:1, and more preferably 1.5:1:1.

[0014] In this invention, the dispersant is preferably sodium polycarboxylate, the leveling agent is preferably isophorone, and the anti-settling agent is preferably hydrophilic fumed silica or silane-modified bentonite.

[0015] Sodium polycarboxylate can solve the problem of agglomeration and clumping of nano-flame retardant fillers through the dual effects of electrostatic repulsion and steric hindrance, allowing the nano-flame retardant fillers to be uniformly dispersed in polyurethane emulsions, reducing the occurrence of coating stratification and clumping during storage and application. Simultaneously, it has good compatibility with water-based systems and will not disrupt the film-forming properties of the emulsion, ensuring both the dispersion of the nano-flame retardant fillers and uniform coating application, avoiding localized cracking from thick coatings or flame retardant failure from thin coatings. Isophorone, a high-boiling-point inert leveling agent, can effectively extend the surface drying time of coatings, reducing defects such as brush marks, sagging, and edge shrinkage during cable coating application, resulting in a smooth and even coating surface and ensuring the coating's application performance. It can also reduce the interfacial tension between the coating and the cable, improving coating adhesion and preventing peeling after film formation. Hydrophilic fumed silica or silane-modified bentonite both possess excellent thixotropic properties, preventing filler sedimentation, stratification, and clumping during long-term storage, thus extending the coating's shelf life.

[0016] The present invention also provides a method for preparing the above-mentioned water-based nano-cable fireproof coating, comprising the following steps: mixing polyurethane emulsion, nano flame-retardant filler, ammonium polyphosphate, melamine, charring agent, foaming agent, additives and water, and then stirring and grinding them in sequence to obtain the water-based nano-cable fireproof coating.

[0017] In this invention, the stirring speed is preferably 300-1200 r / min, more preferably 600-1000 r / min, and even more preferably 700-800 r / min; the stirring time is preferably 25-50 min, more preferably 30-45 min, and even more preferably 35-40 min; and the target particle size for grinding is preferably 80-90 µm.

[0018] The present invention has the following beneficial effects: This invention provides a water-based nano-cable fire-retardant coating, comprising the following raw materials in parts by weight: 45-55 parts polyurethane emulsion, 12-18 parts nano flame-retardant filler, 10-13 parts ammonium polyphosphate, 7-10 parts melamine, 5-8 parts charring agent, 5-8 parts foaming agent, 4-8 parts additives, and 20-40 parts water; wherein the nano flame-retardant filler is a silane-modified nano filler, and the nano filler includes aluminum hydroxide, magnesium hydroxide, and zinc borate.

[0019] This invention uses silane-modified nano-flame-retardant fillers, which have good compatibility with water-based systems after modification, and can fully exert the heat absorption, smoke suppression, oxygen isolation, and flame retardant effects of nano-flame-retardant fillers. At the same time, it is compounded with ammonium polyphosphate, melamine, urea-formaldehyde resin (foaming agent) and charring agents (pentaerythritol and dipentaerythritol), which can quickly form a uniform and dense sponge-like expanded char layer after being exposed to fire. This char layer can effectively block heat and flame propagation for a long time, significantly improve the fire resistance limit of the coating, and effectively protect cables from rapid burning in a fire.

[0020] This invention selects aluminum hydroxide, magnesium hydroxide, and zinc borate as nano flame-retardant fillers. When heated, aluminum hydroxide and magnesium hydroxide absorb heat and dehydrate, releasing water of crystallization that carries away a large amount of heat, lowering the system temperature. At the same time, they generate high-temperature resistant metal oxides, forming an inorganic heat-insulating layer that blocks oxygen from spreading the flame. Zinc borate, as a flame-retardant synergist, not only retards itself but also inhibits the generation of molten droplets during combustion, preventing secondary flame spread. The zinc ions generated when heated can act as "nucleation centers," inducing rapid cross-linking and polymerization of charring agents (pentaerythritol and dipentaerythritol), promoting the formation of the initial char layer, and enhancing the heat insulation effect of the intumescent flame-retardant system.

[0021] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0022] Figure 1 This is a comparison chart of the limiting oxygen index of the fire-retardant coatings prepared in Examples 1-5 and Comparative Examples 1-4 of the present invention. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments. Unless otherwise defined, the technical or scientific terms used in this invention should be understood in their ordinary sense by those skilled in the art. The features mentioned above or in the specific examples mentioned in this invention can be combined arbitrarily, and these specific embodiments are only used to illustrate the invention and are not intended to limit the scope of the invention.

[0024] In the following examples and comparative examples, the nano-flame retardant fillers are silane-modified nano-fillers. The specific modification process is as follows: Nanofillers (aluminum hydroxide, magnesium hydroxide, zinc borate) were placed in a 5% KH550 aqueous solution (KH550 accounted for 5% of the total mass of the nanofillers) and kept at 55℃ for 40 min for silane modification.

[0025] Example 1 A water-based nano-cable fire-retardant coating is composed of the following raw materials in parts by weight: 45 parts polyurethane emulsion, 12 parts nano flame retardant filler, 13 parts ammonium polyphosphate, 7 parts melamine, 8 parts charring agent, 8 parts urea-formaldehyde resin (foaming agent), 4 parts additives, and 20 parts water.

[0026] The nano flame-retardant filler is composed of 6 parts of silane-modified aluminum hydroxide, 3 parts of silane-modified magnesium hydroxide, and 3 parts of silane-modified zinc borate; Among them, the particle size of silane-modified aluminum hydroxide is 80-100nm, the particle size of silane-modified magnesium hydroxide is 80-100nm, and the particle size of silane-modified zinc borate is 80-100nm.

[0027] The charring agent consists of 4 parts pentaerythritol and 4 parts dipentaerythritol.

[0028] The additives consist of 2 parts sodium polycarboxylate (dispersant), 1 part isophorone (leveling agent), and 1 part hydrophilic fumed silica (anti-settling agent).

[0029] The above-mentioned water-based nano-cable fire-retardant coating is prepared by the following steps: The polyurethane emulsion, nano flame-retardant filler, ammonium polyphosphate, melamine, charring agent, foaming agent, additives, and water are mixed and stirred at 600 r / min for 30 min to obtain a mixture. The mixture is then ground to a particle size of 80-90 µm to obtain the water-based nano cable fireproof coating.

[0030] Example 2 A water-based nano-cable fire-retardant coating is composed of the following raw materials in parts by weight: 55 parts polyurethane emulsion, 18 parts nano flame retardant filler, 10 parts ammonium polyphosphate, 10 parts melamine, 5 parts charring agent, 5 parts urea-formaldehyde resin (foaming agent), 8 parts additives, and 25 parts water.

[0031] The nano flame-retardant filler is composed of 10.8 parts of silane-modified aluminum hydroxide, 3.6 parts of silane-modified magnesium hydroxide, and 3.6 parts of silane-modified zinc borate. Among them, the particle size of silane-modified aluminum hydroxide is 50-80 nm, the particle size of silane-modified magnesium hydroxide is 50-80 nm, and the particle size of silane-modified zinc borate is 50-80 nm.

[0032] The charring agent consists of 2.5 parts pentaerythritol and 2.5 parts dipentaerythritol.

[0033] The additives consist of 3.2 parts sodium polycarboxylate (dispersant), 3.2 parts isophorone (leveling agent), and 1.6 parts hydrophilic fumed silica (anti-settling agent).

[0034] The above-mentioned water-based nano-cable fire-retardant coating is prepared by the following steps: The polyurethane emulsion, nano flame-retardant filler, ammonium polyphosphate, melamine, charring agent, foaming agent, additives, and water are mixed and stirred at 1000 r / min for 25 min to obtain a mixture. The mixture is then ground to a particle size of 80-90 µm to obtain the water-based nano cable fireproof coating.

[0035] Example 3 A water-based nano-cable fire-retardant coating is composed of the following raw materials in parts by weight: 52 parts polyurethane emulsion, 16 parts nano flame retardant filler, 12 parts ammonium polyphosphate, 8 parts melamine, 7 parts charring agent, 6 parts urea-formaldehyde resin (foaming agent), 7 parts additives, and 35 parts water.

[0036] The nano flame-retardant filler is composed of 9.6 parts of silane-modified aluminum hydroxide, 3.2 parts of silane-modified magnesium hydroxide, and 3.2 parts of silane-modified zinc borate. Among them, the particle size of silane-modified aluminum hydroxide is 30-50 nm, the particle size of silane-modified magnesium hydroxide is 30-50 nm, and the particle size of silane-modified zinc borate is 30-50 nm.

[0037] The charring agent consists of 4.2 parts pentaerythritol and 2.8 parts dipentaerythritol.

[0038] The additives consist of 1.75 parts sodium polycarboxylate (dispersant), 3.5 parts isophorone (leveling agent), and 1.75 parts hydrophilic fumed silica (anti-settling agent).

[0039] The above-mentioned water-based nano-cable fire-retardant coating is prepared by the following steps: The polyurethane emulsion, nano flame-retardant filler, ammonium polyphosphate, melamine, charring agent, foaming agent, additives, and water are mixed and stirred at 700 r / min for 45 min to obtain a mixture. The mixture is then ground to a particle size of 80-90 µm to obtain the water-based nano cable fireproof coating.

[0040] Example 4 A water-based nano-cable fire-retardant coating is composed of the following raw materials in parts by weight: The composition includes 48 parts polyurethane emulsion, 14 parts nano flame retardant filler, 11 parts ammonium polyphosphate, 9 parts melamine, 6 parts charring agent, 7 parts urea-formaldehyde resin (foaming agent), 5 parts additives, and 40 parts water.

[0041] The nano flame-retardant filler consists of 7 parts silane-modified aluminum hydroxide, 3.5 parts silane-modified magnesium hydroxide, and 3.5 parts silane-modified zinc borate. Among them, the particle size of silane-modified aluminum hydroxide is 10-30 nm, the particle size of silane-modified magnesium hydroxide is 10-30 nm, and the particle size of silane-modified zinc borate is 10-30 nm.

[0042] The charring agent consists of 4 parts pentaerythritol and 2 parts dipentaerythritol.

[0043] The additives consist of 1.75 parts sodium polycarboxylate (dispersant), 3.5 parts isophorone (leveling agent), and 1.75 parts hydrophilic fumed silica (anti-settling agent).

[0044] The above-mentioned water-based nano-cable fire-retardant coating is prepared by the following steps: The polyurethane emulsion, nano flame-retardant filler, ammonium polyphosphate, melamine, charring agent, foaming agent, additives, and water are mixed and stirred at 800 r / min for 35 min to obtain a mixture. The mixture is then ground to a particle size of 80-90 µm to obtain the water-based nano cable fireproof coating.

[0045] Example 5 A water-based nano-cable fire-retardant coating is composed of the following raw materials in parts by weight: 50 parts polyurethane emulsion, 15 parts nano flame retardant filler, 12 parts ammonium polyphosphate, 9 parts melamine, 7 parts charring agent, 7 parts urea-formaldehyde resin (foaming agent), 5 parts additives, and 30 parts water.

[0046] The nano flame-retardant filler consists of 9 parts of silane-modified aluminum hydroxide, 3 parts of silane-modified magnesium hydroxide, and 3 parts of silane-modified zinc borate; Among them, the particle size of silane-modified aluminum hydroxide is 80-100nm, the particle size of silane-modified magnesium hydroxide is 80-100nm, and the particle size of silane-modified zinc borate is 80-100nm.

[0047] The charring agent consists of 3.5 parts pentaerythritol and 3.5 parts dipentaerythritol.

[0048] The additives consist of 2 parts sodium polycarboxylate (dispersant), 2 parts isophorone (leveling agent), and 1 part hydrophilic fumed silica (anti-settling agent).

[0049] The above-mentioned water-based nano-cable fire-retardant coating is prepared by the following steps: The polyurethane emulsion, nano flame-retardant filler, ammonium polyphosphate, melamine, charring agent, foaming agent, additives, and water are mixed and stirred at 800 r / min for 30 min to obtain a mixture. The mixture is then ground to a particle size of 80-90 µm to obtain the water-based nano cable fireproof coating.

[0050] Comparative Example 1 The composition is basically the same as that of the water-based nano-cable fireproof coating provided in Example 1, the only difference being that no nano flame-retardant filler is added, and its preparation process is the same as that in Example 1.

[0051] Comparative Example 2 The composition is basically the same as that of the water-based nano-cable fireproof coating provided in Example 1, the only difference being that no charring agent is added, and its preparation process is the same as that in Example 1.

[0052] Comparative Example 3 The composition is basically the same as that of the water-based nano-cable fireproof coating provided in Example 1, except that the charring agent is 8 parts of pentaerythritol, and its preparation process is the same as that in Example 1.

[0053] Comparative Example 4 The composition is basically the same as that of the water-based nano-cable fireproof coating provided in Example 1, except that the nano flame-retardant filler is composed of 6 parts of silane-modified aluminum hydroxide and 6 parts of silane-modified magnesium hydroxide, and its preparation process is the same as that in Example 1.

[0054] Characterization tests: The fire-retardant coatings obtained in Examples 1-5 and Comparative Examples 1-4 were characterized and tested, and the results are shown in Table 1.

[0055] The process of state testing is as follows: let the fire retardant coating stand at room temperature (25℃) for 14 days and observe the state of the emulsion. If the state is thick and there is no clumping, it indicates good stability.

[0056] Viscosity was tested according to GB / T 1723-1993 "Determination of Viscosity of Coatings"; drying time was tested according to GB / T 1728-2020 "Determination of Drying Time of Paint Film and Putty Film".

[0057] Table 1 Characterization test results

[0058] As shown in Table 1, the fire-retardant coating provided by this invention exhibits no clumping after 14 days of standing, demonstrating good stability. Furthermore, its viscosity is consistently >70s, and both surface-drying and fully-drying times are moderate, meeting the requirements for on-site application. In Comparative Example 1, the lack of nano-flame-retardant fillers resulted in a lower proportion of solid phase in the system, leading to a decrease in viscosity.

[0059] Performance testing: The limiting oxygen index and UL94 vertical burning rating of the fire-retardant coatings prepared in Examples 1-5 and Comparative Examples 1-4 were tested, and the results are shown in Table 2.

[0060] The limiting oxygen index comparison charts for Examples 1-5 and Comparative Examples 1-4 are shown below. Figure 1 .

[0061] The limiting oxygen index was tested according to the GB / T2408-2008 standard; the UL94 vertical burning test was conducted according to the UL-94 fire rating.

[0062] Table 2 Performance Test Results

[0063] As shown in Table 2, the fire-retardant coating provided by this invention has excellent flame-retardant properties. The limiting oxygen index is ≥32.0%, and the UL-94 rating reaches V0. Comparative Example 1, lacking nano-flame-retardant fillers, cannot effectively support the char layer, leading to easy detachment and decreased flame-retardant performance. Comparative Example 2, lacking charring agents, cannot effectively control combustion behavior, relying solely on nano-flame-retardant fillers for simple heat absorption and cooling. Comparative Example 3, with only pentaerythritol, can only achieve rapid charring in the initial stage of the flame; under sustained high temperatures, the char layer is loose and prone to cracking, failing to provide long-term heat and flame insulation. Comparative Example 4, lacking silane-modified zinc borate, experiences decreased density in the char layer, weakening its heat and oxygen insulation effects.

[0064] from Figure 1 It can be seen that the fire-retardant coating provided by the present invention exhibits good uniformity in its limiting oxygen index, with values ​​of ≥32.0% in each embodiment and small fluctuations, proving that the flame-retardant performance of the fire-retardant coating is stable and controllable, and has the feasibility and practical application value for large-scale industrial production.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A water-based nano-cable fire-retardant coating, characterized in that, The raw materials include the following parts by weight: 45-55 parts polyurethane emulsion, 12-18 parts nano flame retardant filler, 10-13 parts ammonium polyphosphate, 7-10 parts melamine, 5-8 parts charring agent, 5-8 parts foaming agent, 4-8 parts additives, and 20-40 parts water. The nano-flame retardant filler is a silane-modified nano-filler, which includes aluminum hydroxide, magnesium hydroxide, and zinc borate.

2. The water-based nano-cable fire-retardant coating according to claim 1, characterized in that, The raw materials include the following parts by weight: 48-52 parts polyurethane emulsion, 14-16 parts nano flame retardant filler, 11-12 parts ammonium polyphosphate, 8-9 parts melamine, 6-7 parts charring agent, 6-7 parts foaming agent, 5-7 parts additives, and 25-35 parts water.

3. The water-based nano-cable fire-retardant coating according to claim 1, characterized in that, The particle sizes of aluminum hydroxide, magnesium hydroxide, and zinc borate are each independently 10-100 nm; The mass ratio of aluminum hydroxide, magnesium hydroxide, and zinc borate is 2-3:1:

1.

4. The water-based nano-cable fire-retardant coating according to claim 1 or 2, characterized in that, The char-forming agent includes pentaerythritol and dipentaerythritol.

5. The water-based nano-cable fire-retardant coating according to claim 4, characterized in that, The mass ratio of pentaerythritol to dipentaerythritol is 1-2:

1.

6. The water-based nano-cable fire-retardant coating according to claim 1 or 2, characterized in that, The foaming agent is urea-formaldehyde resin.

7. The water-based nano-cable fire-retardant coating according to claim 1 or 2, characterized in that, The additives include dispersants, leveling agents, and anti-settling agents; The mass ratio of the dispersant, leveling agent, and anti-settling agent is 1-2:1-2:

1.

8. The water-based nano-cable fire-retardant coating according to claim 7, characterized in that, The dispersant is sodium polycarboxylate, the leveling agent is isophorone, and the anti-settling agent is hydrophilic fumed silica or silane-modified bentonite.

9. A method for preparing the water-based nano-cable fire-retardant coating according to any one of claims 1-8, characterized in that, Includes the following steps: The water-based nano-cable fireproof coating is obtained by mixing polyurethane emulsion, nano flame-retardant filler, ammonium polyphosphate, melamine, charring agent, foaming agent, additives, and water, followed by stirring and grinding.

10. The preparation method according to claim 9, characterized in that, The stirring speed is 300-1200 r / min, the time is 25-50 min, and the target particle size for grinding is 80-90 µm.

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