Novel halogen-free phosphorus-nitrogen synergistic system cable material special flame retardant

Abstract

This invention belongs to the field of flame retardant technology, specifically a novel halogen-free phosphorus-nitrogen synergistic flame retardant for optical cable materials. By weight, it comprises: 35-50 parts of a phosphorus-based flame retardant main agent, 25-40 parts of a nitrogen-based flame retardant main agent, 5-15 parts of a synergistic enhancer, 3-8 parts of a compatibility modifier, 2-5 parts of an anti-exudation agent, and 1-3 parts of a heat stabilizer; the phosphorus-based flame retardant main agent is a compound of halogen-free organophosphorus compounds and inorganic phosphorus compounds; the nitrogen-based flame retardant main agent is a compound of melamine derivatives and low-free-formaldehyde urea-formaldehyde resin; and the synergistic enhancer is a compound of nano-magnesium hydroxide and organically modified montmorillonite. The flame retardant of this invention is halogen-free and environmentally friendly, complies with international and domestic environmental regulations, has high flame retardant efficiency, and can achieve UL94 V-0 rating for optical cable materials with an addition of 15%-20%. It also has good compatibility with optical cable material substrates, excellent thermal stability, and controllable cost, making it suitable for large-scale industrial production. It can be widely used in the flame retardant modification of optical cable sheaths and insulation layers in densely populated indoor places such as office buildings and residences.

Description

Technical Field

[0001] This invention relates to the field of flame retardant technology, and in particular to a novel halogen-free phosphorus-nitrogen synergistic flame retardant for optical cable materials. Background Technology

[0002] With the rapid development of communication technologies such as 5G and the Internet of Things, the application scenarios of indoor optical cables are becoming increasingly widespread. As the core carrier of information transmission, optical cables are widely used in densely populated places such as office buildings, residences, hospitals, and shopping malls. Their flame retardant performance is directly related to the safety of people's lives and property and the integrity of communication facilities. At present, the flame retardants commonly used in indoor optical cable materials are mainly divided into two categories: halogenated flame retardants and halogen-free flame retardants. Although halogenated flame retardants (such as bromine-based and chlorine-based flame retardants) have high flame retardant efficiency and low cost, they release a large amount of toxic and corrosive hydrogen halide gas and dense smoke during combustion. This can not only cause poisoning and suffocation but also corrode communication equipment, failing to meet the high requirements of modern indoor environmental protection and fire safety, and their use has been gradually restricted. Halogen-free flame retardants, due to their low smoke, low toxicity, and no corrosive gas release during combustion, have become the mainstream development direction for indoor optical cable materials.

[0003] Halogen-free flame retardants have become the mainstream choice for indoor optical cable materials due to their low smoke production and lack of toxic and corrosive gas release during combustion. Among them, phosphorus-nitrogen synergistic flame retardants have been widely researched and applied due to their high flame retardant efficiency and excellent environmental performance. However, existing phosphorus-nitrogen synergistic flame retardants still have many shortcomings in indoor optical cable material applications: First, the ratio of phosphorus and nitrogen components is unreasonable, and the synergistic effect is not fully realized, resulting in a high amount of flame retardant added. This not only increases the production cost of optical cable materials but also affects their mechanical and processing properties. Second, some flame retardants have poor thermal stability and are easily decomposed during the optical cable material processing (usually at 150-200 ℃), leading to a decrease in flame retardant effect and potentially producing a small amount of harmful byproducts. Third, some flame retardants have poor compatibility with the optical cable material substrate (such as polyethylene and polypropylene), easily resulting in precipitation and agglomeration, which affects the long-term stability of the optical cable.

[0004] Therefore, there is an urgent need to develop a special flame retardant that is halogen-free, has high phosphorus-nitrogen synergistic efficiency, good compatibility with indoor optical cable substrates, excellent thermal stability, and suitable processing performance. Summary of the Invention

[0005] The technical problem to be solved by this invention is to address the technical defects of existing halogen-free phosphorus-nitrogen synergistic flame retardants for indoor optical cable materials, such as poor phosphorus-nitrogen synergistic effect, poor compatibility with substrate, and poor thermal stability. The invention designs a new type of halogen-free phosphorus-nitrogen synergistic flame retardant for optical cable materials to solve the existing technical problems.

[0006] To solve the above-mentioned technical problems, the novel halogen-free phosphorus-nitrogen synergistic flame retardant for optical cable materials of the present invention comprises, by weight, 35-50 parts of phosphorus-based flame retardant main agent, 25-40 parts of nitrogen-based flame retardant main agent, 5-15 parts of synergistic enhancer, 3-8 parts of compatibility modifier, 2-5 parts of anti-exudation agent, and 1-3 parts of heat stabilizer; wherein the phosphorus-based flame retardant main agent is a compound of halogen-free organophosphorus compound and inorganic phosphorus compound, and the halogen-free organophosphorus compound and inorganic phosphorus compound... The compound has a compounding mass ratio of 2:1 to 3:1; the nitrogen-based flame retardant is a compound of melamine derivatives and low-free-formaldehyde urea-formaldehyde resin, with a compounding mass ratio of melamine derivatives to low-free-formaldehyde urea-formaldehyde resin of 3:1 to 4:1; the synergistic agent is a compound of nano-magnesium hydroxide and organically modified montmorillonite, with a compounding mass ratio of nano-magnesium hydroxide to organically modified montmorillonite of 1:1 to 2:1.

[0007] Furthermore, in the phosphorus-based flame retardant main agent of the present invention, the halogen-free organophosphorus compound is selected from one or two of phosphate esters and phosphonates, and the inorganic phosphorus compound is selected from one or two of ammonium polyphosphate and aluminum dihydrogen phosphate.

[0008] Furthermore, in this invention, the halogen-free organophosphorus compound is aluminum diethylphosphonate, the inorganic phosphorus compound is ammonium polyphosphate with a degree of polymerization n≥1000, and the mass ratio of aluminum diethylphosphonate to ammonium polyphosphate is 2.5:1.

[0009] Furthermore, in the nitrogen-based flame retardant main agent, the melamine derivative is selected from one or two of melamine phosphate and melamine polyphosphate, and the free formaldehyde content of the low free formaldehyde urea-formaldehyde resin is ≤0.1%.

[0010] Furthermore, in this invention, the melamine derivative is melamine polyphosphate, and the mass ratio of low free formaldehyde urea-formaldehyde resin to melamine polyphosphate is 3.5:1.

[0011] Furthermore, in the synergistic agent, the particle size of the nano-magnesium hydroxide is 50 nm to 100 nm, the organically modified montmorillonite is montmorillonite modified with a silane coupling agent, and the mass ratio of nano-magnesium hydroxide to organically modified montmorillonite is 1.5:1.

[0012] Furthermore, in this invention, the compatibility modifier is selected from one or two of silane coupling agents and maleic anhydride-grafted polyethylene, and the mass ratio of the mixture is 1:1 to 1:2.

[0013] Furthermore, in this invention, the anti-exudation agent is selected from one or a combination of two of polyethylene glycol (PEG-4000) and polypropylene glycol (PPG-2000), with a mass ratio of 1:1 to 2:1.

[0014] Furthermore, in this invention, the heat stabilizer is selected from one or two of hindered phenolic antioxidants and phosphite antioxidants, and the mass ratio of the mixture is 1:1 to 1:2.

[0015] Furthermore, the preparation method of the novel halogen-free phosphorus-nitrogen synergistic flame retardant for optical cable materials in this invention includes the following steps: Step S1: Pretreatment: Place the phosphorus-based flame retardant and the nitrogen-based flame retardant in a vacuum drying oven and dry them at 80 ℃~100 ℃ for 2 h~3 h to remove moisture and avoid agglomeration during the preparation process; perform surface activation treatment on the nano magnesium hydroxide in the synergistic agent, add 0.5%~1% of its mass of silane coupling agent KH-570, stir at 1000 r / min~1200 r / min in a high-speed mixer for 30 min~40 min, cool to room temperature for later use to improve its dispersibility and compatibility; Step S2: Mixing: Add the pretreated phosphorus-based flame retardant, nitrogen-based flame retardant, synergist, compatibility modifier, anti-exudation agent, and heat stabilizer to a high-speed mixer according to the above mass percentages. Mix for 30 min to 40 min at 80 ℃~90 ℃ and 1500 r / min~2000 r / min to ensure that each agent is uniformly dispersed and forms a mixture. Step S3: Melt extrusion: The mixture is fed into a twin-screw extruder, and the extrusion temperature is controlled at 160 ℃~180 ℃ and the screw speed is 200 r / min~300 r / min. Melting, mixing and extrusion are carried out, and the extruded material is cooled to room temperature by water cooling. Step S4: Crushing and Screening: The cooled extruded material is fed into a crusher for crushing. After crushing, it is screened through an 80-100 mesh screen to remove coarse particles and obtain the finished product of halogen-free phosphorus and nitrogen synergistic flame retardant for indoor optical cable materials.

[0016] The beneficial effects of this invention are: This invention relates to a novel halogen-free phosphorus-nitrogen synergistic flame retardant for optical cable materials. It optimizes the selection and ratio of phosphorus and nitrogen components, employing a combination of organic and inorganic phosphorus compounds, melamine derivatives, and low-free-formaldehyde urea-formaldehyde resin. This is combined with the synergistic effect of nano-magnesium hydroxide and organically modified montmorillonite, forming a dual synergistic flame retardant system of phosphorus and nitrogen-inorganic compounds. During combustion, the phosphorus components generate polymetaphosphoric acid, promoting char formation. During combustion, the nitrogen components release non-combustible gases, diluting oxygen and expanding the char layer. The synergistic components further promote char layer formation and block heat transfer. The combined effect of these three components significantly improves flame retardant efficiency, requiring only 15%-20% (mass fraction) of the flame retardant in the optical cable material to achieve UL94 compliance. The V-0 flame retardant standard, with a limiting oxygen index (LOI) ≥30%, is far superior to existing phosphorus-nitrogen synergistic flame retardants (which typically require more than 25%). This solves the technical defects of existing phosphorus-nitrogen synergistic flame retardants, such as high addition amounts and insufficient flame retardant efficiency. At the same time, it can reduce the impact of flame retardants on the mechanical properties of optical cable materials, ensuring that the tensile strength, elongation at break, and other indicators of optical cable materials meet the requirements for indoor optical cable use (tensile strength ≥15MPa, elongation at break ≥300%). It balances flame retardant performance and mechanical properties, better meeting the needs of indoor optical cable use scenarios, and solving the problem of poor compatibility of existing general-purpose flame retardants. Furthermore, by adding a compatibility-modifying component (a compound of silane coupling agent KH-550 and maleic anhydride-grafted polyethylene), this invention effectively improves the interfacial bonding force between the flame retardant and the optical cable material substrate (polyethylene, polypropylene, etc.), avoiding the agglomeration and precipitation of the flame retardant and ensuring the surface smoothness and processing performance of the optical cable material. At the same time, by adding a heat-stabilizing component (a compound of antioxidant 1010 and antioxidant 168), the thermal decomposition temperature of the flame retardant is increased to over 300°C, which is much higher than the processing temperature of the optical cable material (150-200°C). This avoids the decomposition of the flame retardant during processing, ensures stable flame retardant effect, and prevents aging of the optical cable material substrate, extending the service life of the optical cable. This invention solves the technical defects of poor compatibility and insufficient thermal stability of existing phosphorus and nitrogen flame retardants. Detailed Implementation

[0017] The novel halogen-free phosphorus-nitrogen synergistic flame retardant for optical cable materials in this embodiment includes, by weight, 35-50 parts of phosphorus-based flame retardant main agent, 25-40 parts of nitrogen-based flame retardant main agent, 5-15 parts of synergistic enhancer, 3-8 parts of compatibility modifier, 2-5 parts of anti-exudation agent, and 1-3 parts of heat stabilizer; the phosphorus-based flame retardant main agent is a compound of halogen-free organophosphorus compounds and inorganic phosphorus compounds, with a compounding mass ratio of halogen-free organophosphorus compounds to inorganic phosphorus compounds of 2:1-3:1; the nitrogen-based flame retardant main agent is a compound of melamine derivatives and low-free formaldehyde urea-formaldehyde resin, with a compounding mass ratio of melamine derivatives to low-free formaldehyde urea-formaldehyde resin of 3:1-4:1; the synergistic enhancer is a compound of nano-magnesium hydroxide and organically modified montmorillonite, with a compounding mass ratio of nano-magnesium hydroxide to organically modified montmorillonite of 1:1-2:1.

[0018] Preferably, in this embodiment, the halogen-free organophosphorus compound in the phosphorus-based flame retardant is selected from one or a combination of two of phosphate esters and phosphines, and the inorganic phosphorus compound is selected from one or a combination of two of ammonium polyphosphate and aluminum dihydrogen phosphate. Specifically, in this embodiment, the phosphate ester is triphenyl phosphate, tributyl phosphate, or triethyl phosphate, and the phosphines are aluminum diethylphosphines, aluminum methylphosphines, or zinc ethylphosphines.

[0019] In this embodiment, preferably, the halogen-free organophosphorus compound is aluminum diethylphosphonate, and the inorganic phosphorus compound is ammonium polyphosphate with a degree of polymerization n ≥ 1000. The mass ratio of aluminum diethylphosphonate to ammonium polyphosphate is 2.5:1. Aluminum diethylphosphonate is halogen-free and has a high phosphorus content, excellent flame retardant efficiency, good compatibility with polymer substrates, and releases no toxic gases during combustion. Ammonium polyphosphate is inexpensive, has a high phosphorus content, is halogen-free and environmentally friendly, has good thermal stability (decomposition temperature ≥ 280℃), can form a good synergistic effect with nitrogen-based components, and is a low-hazard substance recognized by the European ECHA, requiring no special regulation. The combination of the two can balance flame retardant efficiency and cost, avoiding the defects of excessively high cost of a single organophosphorus component and poor compatibility of a single inorganic phosphorus component.

[0020] In this embodiment, preferably, the melamine derivative in the nitrogen-based flame retardant is selected from one or two of melamine phosphate and melamine polyphosphate, and the free formaldehyde content of the low-free formaldehyde urea-formaldehyde resin is ≤0.1%. Melamine polyphosphate is halogen-free, high in nitrogen, and has excellent thermal stability (decomposition temperature ≥300℃). During combustion, it decomposes to produce non-combustible gases such as ammonia and nitrogen, which can dilute the oxygen in the air. At the same time, it forms an expanded char layer with the polymetaphosphoric acid produced by the decomposition of phosphorus-based components, exerting a synergistic flame retardant effect of phosphorus and nitrogen. Moreover, it is not a SVHC (Substances of Very High Concern) and complies with environmental regulations. Low-free formaldehyde urea-formaldehyde resin is inexpensive, has a high nitrogen content, and can help improve the flame retardant effect. At the same time, its own binding properties can improve the agglomeration of flame retardants, and its free formaldehyde content is extremely low, avoiding harm to human health and meeting the requirements for indoor use. When compounded with melamine polyphosphate, it can further improve the synergistic flame retardant efficiency, reduce costs, and avoid the problem of insufficient flame retardant efficiency of a single nitrogen-based component.

[0021] In this embodiment, preferably, the melamine derivative is melamine polyphosphate, and the mass ratio of low free formaldehyde urea-formaldehyde resin to melamine polyphosphate is 3.5:1.

[0022] In this embodiment, preferably, the nano-magnesium hydroxide in the synergistic synergist has a particle size of 50 nm to 100 nm, and the organically modified montmorillonite is montmorillonite modified with a silane coupling agent. The mass ratio of nano-magnesium hydroxide to organically modified montmorillonite is 1.5:1. Nano-magnesium hydroxide is halogen-free, non-toxic, and environmentally friendly. It releases water of crystallization during combustion, which cools and suppresses smoke. Simultaneously, it promotes char layer formation and synergistically enhances flame retardant efficiency with phosphorus and nitrogen components, and is also inexpensive. Organically modified montmorillonite has a layered structure, which can enhance the dispersibility of flame retardants and improve the mechanical properties of optical cable materials. At the same time, its layered structure can form a physical barrier during combustion, blocking heat and oxygen transfer, further enhancing the flame retardant effect. When combined with nano-magnesium hydroxide, it can achieve "phosphorus-nitrogen-inorganic synergy", solving the shortcomings of single phosphorus-nitrogen synergy in smoke suppression and cooling, while avoiding compatibility problems caused by the agglomeration of nano-magnesium hydroxide. Both components meet environmental protection and human health requirements, and the cost is controllable, which can further reduce the amount of flame retardant added and improve cost performance. Compared with single synergistic components in existing technologies, the synergistic effect is more comprehensive, and it can simultaneously achieve multiple effects such as flame retardancy, smoke suppression, and enhanced dispersibility.

[0023] In this embodiment, preferably, the compatibility modifier is selected from one or a combination of two of silane coupling agents and maleic anhydride-grafted polyethylene, with a mass ratio of 1:1 to 1:2. The silane coupling agent KH-550 can improve the interfacial bonding force between the flame retardant and the optical cable material substrate (polyethylene, polypropylene, etc.), reducing the agglomeration and precipitation of the flame retardant. Maleic anhydride-grafted polyethylene (MAH-g-PE) has excellent compatibility with the optical cable material substrate and can act as a bridge to further improve the uniformity of the flame retardant dispersion in the substrate, avoiding the decline in the mechanical properties of the optical cable material due to flame retardant agglomeration. Both components are halogen-free and low-toxic, meeting environmental protection and human health requirements, and are inexpensive. They are suitable for indoor optical cable material processing technologies (such as extrusion and injection molding), solving the technical pain point of poor compatibility between existing phosphorus and nitrogen flame retardants and optical cable material substrates, and improving the processing performance and long-term stability of the optical cable material.

[0024] In this embodiment, preferably, the anti-exudation agent is selected from one or a combination of two of polyethylene glycol (PEG-4000) and polypropylene glycol (PPG-2000), with a mass ratio of 1:1 to 2:1. PEG-4000 is halogen-free, non-toxic, and environmentally friendly. It has good compatibility with the components of the flame retardant and the optical cable material substrate. It can form a protective film on the surface of the flame retardant particles, preventing the flame retardant from precipitating during the processing and use of the optical cable material. This ensures the surface smoothness and long-term stability of the optical cable material. Furthermore, it is inexpensive, requiring only a small amount to achieve good anti-exudation effects, avoiding the defects of existing flame retardants that easily precipitate and affect optical cable performance. It also meets the health requirements for indoor use and is non-irritating.

[0025] In this embodiment, preferably, the heat stabilizer is selected from one or a combination of two hindered phenolic antioxidants (antioxidant 1010) and phosphite antioxidants (antioxidant 168), with a mass ratio of 1:1 to 1:2. The combination of antioxidant 1010 and antioxidant 168 can exert a synergistic heat stabilizing effect, effectively inhibiting the thermal decomposition of the flame retardant during the optical cable material processing (150-200℃), improving the thermal stability of the flame retardant, ensuring that the flame retardant effect does not decrease, and preventing aging of the optical cable material substrate, thus extending the service life of the optical cable. Both antioxidants are halogen-free and low in toxicity, meeting environmental protection and human health requirements, and are inexpensive, requiring only a small amount to avoid increasing production costs. This solves the technical defects of existing phosphorus and nitrogen flame retardants, such as insufficient thermal stability and easy decomposition during processing, and is suitable for the processing technology requirements of indoor optical cable materials.

[0026] In this embodiment, the preferred method for preparing the novel halogen-free phosphorus-nitrogen synergistic flame retardant for optical cable materials includes the following steps: Step S1: Pretreatment: Place the phosphorus-based flame retardant and the nitrogen-based flame retardant in a vacuum drying oven and dry them at 80 ℃~100 ℃ for 2 h~3 h to remove moisture and avoid agglomeration during the preparation process; perform surface activation treatment on the nano magnesium hydroxide in the synergistic agent, add 0.5%~1% of its mass of silane coupling agent KH-570, stir at 1000 r / min~1200 r / min in a high-speed mixer for 30 min~40 min, cool to room temperature for later use to improve its dispersibility and compatibility; Step S2: Mixing: Add the pretreated phosphorus-based flame retardant, nitrogen-based flame retardant, synergist, compatibility modifier, anti-exudation agent, and heat stabilizer to a high-speed mixer according to the above mass percentages. Mix for 30 min to 40 min at 80 ℃~90 ℃ and 1500 r / min~2000 r / min to ensure that each agent is uniformly dispersed and forms a mixture. Step S3: Melt extrusion: The mixture is fed into a twin-screw extruder, and the extrusion temperature is controlled at 160 ℃~180 ℃ and the screw speed is 200 r / min~300 r / min. Melting, mixing and extrusion are carried out, and the extruded material is cooled to room temperature by water cooling. Step S4: Crushing and Screening: The cooled extruded material is fed into a crusher for crushing. After crushing, it is screened through an 80-100 mesh screen to remove coarse particles and obtain the finished product of halogen-free phosphorus and nitrogen synergistic flame retardant for indoor optical cable materials. Example 1

[0027] The novel halogen-free phosphorus-nitrogen synergistic flame retardant for optical cable materials in this embodiment comprises, by weight: 35 parts of phosphorus-based flame retardant main agent, wherein the phosphorus-based flame retardant main agent is a compound of aluminum diethylphosphinate and high degree of polymerization ammonium polyphosphate, the mass ratio of aluminum diethylphosphinate to high degree of polymerization ammonium polyphosphate is 2.5:1, and the degree of polymerization of ammonium polyphosphate n≥1000.

[0028] 40 parts of nitrogen-based flame retardant, wherein the nitrogen-based flame retardant is a compound of melamine polyphosphate and low-free-formaldehyde urea-formaldehyde resin, wherein the mass ratio of melamine polyphosphate to low-free-formaldehyde urea-formaldehyde resin is 3.5:1, and the free formaldehyde content of the low-free-formaldehyde urea-formaldehyde resin is ≤0.1%.

[0029] 12 parts of synergistic synergist, wherein the synergistic synergist is a compound of nano-magnesium hydroxide and organically modified montmorillonite, wherein the mass ratio of nano-magnesium hydroxide to organically modified montmorillonite is 1.5:1; wherein the particle size of nano-magnesium hydroxide is 50 nm to 100 nm, and wherein the organically modified montmorillonite is montmorillonite modified with a silane coupling agent. Six parts of compatibility modifier, wherein the compatibility modifier is a compound of silane coupling agent KH-550 and maleic anhydride grafted polyethylene (MAH-g-PE) with a compounding mass ratio of 1.5:1.

[0030] Four parts of anti-precipitation agent, wherein the anti-precipitation agent is polyethylene glycol (PEG-4000).

[0031] Three parts of heat stabilizer; the heat stabilizer is a compound of antioxidant 1010 and antioxidant 168, with a compound mass ratio of 1:2.

[0032] The preparation method of the novel halogen-free phosphorus-nitrogen synergistic flame retardant for optical cable materials in this embodiment includes the following steps: Step S1: Pretreatment: Place the phosphorus-based flame retardant and the nitrogen-based flame retardant in a vacuum drying oven and dry them at 80 ℃ for 3 h to remove moisture and avoid agglomeration during the preparation process; perform surface activation treatment on the nano magnesium hydroxide in the synergistic agent, add 0.7% of its mass of silane coupling agent KH-570, stir at 1000 r / min for 40 min in a high-speed mixer, and cool to room temperature for later use to improve its dispersibility and compatibility; Step S2: Mixing: Add the pretreated phosphorus flame retardant, nitrogen flame retardant, synergist, compatibility modifier, anti-exudation agent, and heat stabilizer to a high-speed mixer according to the above mass percentages, and mix for 36 min at 90 ℃ and 1600 r / min to ensure that each agent is evenly dispersed and forms a mixture. Step S3: Melt extrusion: The mixture is fed into a twin-screw extruder, the extrusion temperature is controlled at 170 ℃ and the screw speed is 280 r / min, and the mixture is melted, mixed and extruded. The extruded material is cooled to room temperature by water cooling. Step S4: Crushing and Screening: The cooled extruded material is fed into a crusher for crushing. After crushing, it is screened through an 80-mesh sieve to remove coarse particles, thus obtaining the finished product of halogen-free phosphorus-nitrogen synergistic flame retardant for indoor optical cable materials. Example 2

[0033] The novel halogen-free phosphorus-nitrogen synergistic flame retardant for optical cable materials in this embodiment comprises, by weight: 45 parts of phosphorus-based flame retardant main agent, wherein the phosphorus-based flame retardant main agent is a compound of halogen-free organophosphorus compound and inorganic phosphorus compound, wherein the halogen-free organophosphorus compound is a compound of triphenyl phosphate and aluminum methylphosphonate, and the inorganic phosphorus compound is a compound of ammonium polyphosphate and aluminum dihydrogen phosphate, wherein the mass ratio of the halogen-free organophosphorus compound to the inorganic phosphorus compound is 2:1.

[0034] 30 parts of nitrogen-based flame retardant, wherein the nitrogen-based flame retardant is a compound of melamine polyphosphate and low-free-formaldehyde urea-formaldehyde resin, wherein the mass ratio of melamine polyphosphate to low-free-formaldehyde urea-formaldehyde resin is 4:1, and the free formaldehyde content of the low-free-formaldehyde urea-formaldehyde resin is ≤0.1%.

[0035] Five parts of a synergistic synergist, wherein the synergistic synergist is a compound of nano-magnesium hydroxide and organically modified montmorillonite, wherein the mass ratio of nano-magnesium hydroxide to organically modified montmorillonite is 1:1; wherein the particle size of nano-magnesium hydroxide is 50 nm to 100 nm, and wherein the organically modified montmorillonite is montmorillonite modified with a silane coupling agent.

[0036] Three parts of a compatibility modifier, wherein the compatibility modifier is a silane coupling agent.

[0037] Two parts of anti-precipitation agent, wherein the anti-precipitation agent is a compound of polyethylene glycol (PEG-4000) and polypropylene glycol (PPG-2000) in a mass ratio of 1:1.

[0038] One part of heat stabilizer; the heat stabilizer is a compound of antioxidant 1010 and antioxidant 168, with a mass ratio of 1:1.5.

[0039] The preparation method of the novel halogen-free phosphorus-nitrogen synergistic flame retardant for optical cable materials in this embodiment includes the following steps: Step S1: Pretreatment: Place the phosphorus-based flame retardant and the nitrogen-based flame retardant in a vacuum drying oven and dry them at 100℃ for 2 h to remove moisture and avoid agglomeration during the preparation process; perform surface activation treatment on the nano magnesium hydroxide in the synergistic agent, add 0.5% of its mass of silane coupling agent KH-570, stir at 1100 r / min for 35 min in a high-speed mixer, and cool to room temperature for later use to improve its dispersibility and compatibility; Step S2: Mixing: Add the pretreated phosphorus flame retardant, nitrogen flame retardant, synergist, compatibility modifier, anti-exudation agent, and heat stabilizer to a high-speed mixer according to the above mass percentages, and mix for 40 min at 80 ℃ and 1500 r / min to ensure that each agent is evenly dispersed and forms a mixture. Step S3: Melt extrusion: The mixture is fed into a twin-screw extruder, the extrusion temperature is controlled at 160 ℃ and the screw speed is 200 r / min, and the mixture is melted, mixed and extruded. The extruded material is cooled to room temperature by water cooling. Step S4: Crushing and Screening: The cooled extruded material is fed into a crusher for crushing. After crushing, it is screened through a 90-mesh sieve to remove coarse particles, thus obtaining the finished product of halogen-free phosphorus-nitrogen synergistic flame retardant for indoor optical cable materials. Example 3

[0040] The novel halogen-free phosphorus-nitrogen synergistic flame retardant for optical cable materials in this embodiment comprises, by weight: 50 parts of phosphorus-based flame retardant, wherein the phosphorus-based flame retardant is a compound of zinc ethylphosphinate and ammonium polyphosphate, wherein the mass ratio of zinc ethylphosphinate to ammonium polyphosphate is 3:1, and the degree of polymerization of ammonium polyphosphate n≥1000.

[0041] 25 parts of nitrogen-based flame retardant main agent, wherein the nitrogen-based flame retardant main agent is a compound of melamine derivatives and low-free-formaldehyde urea-formaldehyde resin, wherein the mass ratio of the melamine derivatives to the low-free-formaldehyde urea-formaldehyde resin is 3:1, wherein the melamine derivatives are a compound of melamine phosphate and melamine polyphosphate, and wherein the free formaldehyde content of the low-free-formaldehyde urea-formaldehyde resin is ≤0.1%.

[0042] 15 parts of synergistic synergist, wherein the synergistic synergist is a compound of nano-magnesium hydroxide and organically modified montmorillonite, wherein the mass ratio of nano-magnesium hydroxide to organically modified montmorillonite is 2:1; wherein the particle size of nano-magnesium hydroxide is 50nm~100nm, and wherein the organically modified montmorillonite is montmorillonite modified with a silane coupling agent.

[0043] Eight parts of a compatibility modifier, wherein the compatibility modifier is maleic anhydride-grafted polyethylene.

[0044] Three parts of anti-precipitation agent, wherein the anti-precipitation agent is a compound of polyethylene glycol (PEG-4000) and polypropylene glycol (PPG-2000) in a mass ratio of 2:1.

[0045] Two parts of heat stabilizer; the heat stabilizer is a compound of antioxidant 1010 and antioxidant 168, with a compound mass ratio of 1:1.

[0046] The preparation method of the novel halogen-free phosphorus-nitrogen synergistic flame retardant for optical cable materials in this embodiment includes the following steps: Step S1: Pretreatment: Place the phosphorus-based flame retardant and the nitrogen-based flame retardant in a vacuum drying oven and dry them at 100℃ for 2 h to remove moisture and avoid agglomeration during the preparation process; perform surface activation treatment on the nano magnesium hydroxide in the synergistic agent, add 1% of its mass of silane coupling agent KH-570, stir at 1200 r / min for 30 min in a high-speed mixer, and cool to room temperature for later use to improve its dispersibility and compatibility; Step S2: Mixing: Add the pretreated phosphorus flame retardant, nitrogen flame retardant, synergist, compatibility modifier, anti-exudation agent, and heat stabilizer to a high-speed mixer according to the above mass percentages, and mix for 30 min at 85℃ and 2000 r / min to ensure that each agent is evenly dispersed and forms a mixture. Step S3: Melt extrusion: The mixture is fed into a twin-screw extruder, the extrusion temperature is controlled at 180 ℃ and the screw speed is 300 r / min, and the mixture is melted, mixed and extruded. The extruded material is cooled to room temperature by water cooling. Step S4: Crushing and Screening: The cooled extruded material is fed into a crusher for crushing. After crushing, it is screened through a 100-mesh sieve to remove coarse particles, thus obtaining the finished product of halogen-free phosphorus and nitrogen synergistic flame retardant for indoor optical cable materials. Example 4

[0047] The novel halogen-free phosphorus-nitrogen synergistic flame retardant for optical cable materials in this embodiment comprises, by weight: 40 parts of phosphorus-based flame retardant main agent, wherein the phosphorus-based flame retardant main agent is a compound of halogen-free organophosphorus compound and inorganic phosphorus compound, and the mass ratio of the halogen-free organophosphorus compound to the inorganic phosphorus compound is 2.5:1. The halogen-free organophosphorus compound is a compound of tributyl phosphate and aluminum diethylphosphonate, and the inorganic phosphorus compound is a compound of highly polymerized ammonium polyphosphate and aluminum dihydrogen phosphate, wherein the degree of polymerization of ammonium phosphate n≥1000.

[0048] 35 parts of nitrogen-based flame retardant main agent, wherein the nitrogen-based flame retardant main agent is a compound of melamine polyphosphate and low free formaldehyde urea formaldehyde resin, wherein the mass ratio of the melamine derivative to the low free formaldehyde urea formaldehyde resin is 3.6:1, and the free formaldehyde content of the low free formaldehyde urea formaldehyde resin is ≤0.1%.

[0049] Ten parts of a synergistic synergist are included. The synergistic synergist is a compound of nano-magnesium hydroxide and organically modified montmorillonite. The mass ratio of the nano-magnesium hydroxide to the organically modified montmorillonite is 1:1.4. The nano-magnesium hydroxide has a particle size of 50 nm to 100 nm. The organically modified montmorillonite is montmorillonite modified with a silane coupling agent.

[0050] Five parts of compatibility modifier, wherein the compatibility modifier is a compound of silane coupling agent and maleic anhydride grafted polyethylene, and the compounding mass ratio is 1:1.

[0051] Five parts of anti-precipitation agent, wherein the anti-precipitation agent is a compound of polyethylene glycol (PEG-4000) and polypropylene glycol (PPG-2000) in a mass ratio of 1:1.5.

[0052] Two parts of heat stabilizer, wherein the heat stabilizer is antioxidant 1010.

[0053] The preparation method of the novel halogen-free phosphorus-nitrogen synergistic flame retardant for optical cable materials in this embodiment includes the following steps: Step S1: Pretreatment: Place the phosphorus-based flame retardant and the nitrogen-based flame retardant in a vacuum drying oven and dry them at 90 ℃ for 2.5 h to remove moisture and avoid agglomeration during the preparation process; perform surface activation treatment on the nano magnesium hydroxide in the synergistic agent, add 0.9% of its mass of silane coupling agent KH-570, stir at 1500 r / min for 38 min in a high-speed mixer, and cool to room temperature for later use to improve its dispersibility and compatibility; Step S2: Mixing: Add the pretreated phosphorus flame retardant, nitrogen flame retardant, synergist, compatibility modifier, anti-exudation agent, and heat stabilizer to a high-speed mixer according to the above mass percentages, and mix for 36 min at 90 ℃ and 1800 r / min to ensure that each agent is evenly dispersed and forms a mixture. Step S3: Melt extrusion: The mixture is fed into a twin-screw extruder, the extrusion temperature is controlled at 1750℃ and the screw speed is 250 r / min, and the mixture is melted, mixed and extruded. The extruded material is cooled to room temperature by water cooling. Step S4: Crushing and Screening: The cooled extruded material is fed into a crusher for crushing. After crushing, it is screened through an 80-mesh sieve to remove coarse particles, thus obtaining the finished product of halogen-free phosphorus-nitrogen synergistic flame retardant for indoor optical cable materials. Example 5

[0054] The novel halogen-free phosphorus-nitrogen synergistic flame retardant for optical cable materials in this embodiment comprises, by weight: 45 parts of phosphorus-based flame retardant, wherein the phosphorus-based flame retardant is a compound of triethyl phosphate and aluminum dihydrogen phosphate, and the mass ratio of triethyl phosphate to aluminum dihydrogen phosphate is 2:1.

[0055] 30 parts of nitrogen-based flame retardant, wherein the nitrogen-based flame retardant is a compound of melamine polyphosphate and low-free-formaldehyde urea-formaldehyde resin, wherein the mass ratio of melamine polyphosphate to low-free-formaldehyde urea-formaldehyde resin is 4:1, and the free formaldehyde content of the low-free-formaldehyde urea-formaldehyde resin is ≤0.1%.

[0056] Eight parts of a synergistic synergist were provided. The synergistic synergist was a compound of nano-magnesium hydroxide and organically modified montmorillonite. The mass ratio of the nano-magnesium hydroxide to the organically modified montmorillonite was 1.8:1. The nano-magnesium hydroxide had a particle size of 50 nm to 100 nm. The organically modified montmorillonite was montmorillonite modified with a silane coupling agent.

[0057] Seven parts of compatibility modifier, wherein the compatibility modifier is a compound of silane coupling agent and maleic anhydride grafted polyethylene, and the compounding mass ratio is 1:2.

[0058] Four parts of anti-precipitation agent, wherein the anti-precipitation agent is polypropylene glycol (PPG-2000).

[0059] Two parts of heat stabilizer, wherein the heat stabilizer is antioxidant 168.

[0060] The preparation method of the novel halogen-free phosphorus-nitrogen synergistic flame retardant for optical cable materials in this embodiment includes the following steps: Step S1: Pretreatment: Place the phosphorus-based flame retardant and the nitrogen-based flame retardant in a vacuum drying oven and dry them at 95 ℃ for 2.2 h to remove moisture and avoid agglomeration during the preparation process; perform surface activation treatment on the nano magnesium hydroxide in the synergistic agent, add 0.6% of its mass of silane coupling agent KH-570, stir at 1000 r / min for 40 min in a high-speed mixer, and cool to room temperature for later use to improve its dispersibility and compatibility; Step S2: Mixing: Add the pretreated phosphorus flame retardant, nitrogen flame retardant, synergist, compatibility modifier, anti-exudation agent, and heat stabilizer to a high-speed mixer according to the above mass percentages, and mix for 33 min at 90 ℃ and 1600 r / min to ensure that each agent is evenly dispersed and forms a mixture. Step S3: Melt extrusion: The mixture is fed into a twin-screw extruder, the extrusion temperature is controlled at 165 ℃ and the screw speed is 270 r / min, and the mixture is melted, mixed and extruded. The extruded material is cooled to room temperature by water cooling. Step S4: Crushing and Screening: The cooled extruded material is fed into a crusher for crushing. After crushing, it is screened through an 80-mesh sieve to remove coarse particles, thus obtaining the finished product of halogen-free phosphorus-nitrogen synergistic flame retardant for indoor optical cable materials.

[0061] The flame retardant products from Examples 1 to 5 were added to polyethylene optical cable material to prepare optical cable sheath samples (sample thickness 1.6 mm). Performance tests were conducted, and the results are as follows:

[0062] Therefore, it can be seen that optical cables prepared using the flame retardant product of this invention can achieve UL94 rating with less flame retardant added. The V-0 flame retardant standard, with a limiting oxygen index (LOI) ≥30%, is far superior to existing phosphorus-nitrogen synergistic flame retardants (which typically require more than 25% addition). Furthermore, the tensile strength and elongation at break of the fiber optic cable material meet the requirements for indoor fiber optic cable use (tensile strength ≥15MPa, elongation at break ≥300%), balancing flame retardant and mechanical properties. In addition, it exhibits excellent processing performance, effectively improving the interfacial bonding between the flame retardant and the fiber optic cable material substrate (polyethylene, polypropylene, etc.), preventing flame retardant agglomeration and precipitation, and ensuring the surface smoothness and processing performance of the fiber optic cable material. Its superior thermal stability raises the thermal decomposition temperature of the flame retardant to over 300℃, far exceeding the processing temperature of the fiber optic cable material (150-200℃), preventing flame retardant decomposition during processing, ensuring stable flame retardant performance, and preventing aging of the fiber optic cable material substrate, thus extending the service life of the fiber optic cable. This addresses the technical shortcomings of existing phosphorus-nitrogen flame retardants, such as poor compatibility and insufficient thermal stability.

[0063] Many specific details have been set forth in the foregoing description to provide a thorough understanding of the present invention. However, the above description is merely a preferred embodiment of the present invention, and the present invention can be implemented in many other ways different from those described herein. Therefore, the present invention is not limited to the specific embodiments disclosed above. Furthermore, any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, using the methods and techniques disclosed above, without departing from the scope of the present invention. Any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention, shall still fall within the protection scope of the present invention.

Claims

1. A novel halogen-free phosphorus-nitrogen synergistic flame retardant for optical cable materials, characterized in that: By weight, it comprises: 35-50 parts of phosphorus-based flame retardant, 25-40 parts of nitrogen-based flame retardant, 5-15 parts of synergist, 3-8 parts of compatibility modifier, 2-5 parts of anti-exudation agent, and 1-3 parts of heat stabilizer; the phosphorus-based flame retardant is a compound of halogen-free organophosphorus compounds and inorganic phosphorus compounds, with a compounding mass ratio of halogen-free organophosphorus compounds to inorganic phosphorus compounds of 2:1 to 3:1; the nitrogen-based flame retardant is a compound of melamine derivatives and low-free formaldehyde urea-formaldehyde resin, with a compounding mass ratio of melamine derivatives to low-free formaldehyde urea-formaldehyde resin of 3:1 to 4:1; the synergist is a compound of nano-magnesium hydroxide and organically modified montmorillonite, with a compounding mass ratio of nano-magnesium hydroxide to organically modified montmorillonite of 1:1 to 2:

1.

2. The novel halogen-free phosphorus-nitrogen synergistic flame retardant for optical cable materials according to claim 1, characterized in that: In the phosphorus-based flame retardant, the halogen-free organophosphorus compound is selected from one or two of phosphate esters and phosphonates, and the inorganic phosphorus compound is selected from one or two of ammonium polyphosphate and aluminum dihydrogen phosphate.

3. The novel halogen-free phosphorus-nitrogen synergistic flame retardant for optical cable materials according to claim 2, characterized in that: The halogen-free organophosphorus compound is aluminum diethylphosphonate, and the inorganic phosphorus compound is ammonium polyphosphate with a degree of polymerization n≥1000. The mass ratio of aluminum diethylphosphonate to ammonium polyphosphate is 2.5:

1.

4. The novel halogen-free phosphorus-nitrogen synergistic flame retardant for optical cable materials according to claim 1, characterized in that: In the nitrogen-based flame retardant, the melamine derivative is selected from one or two of melamine phosphate and melamine polyphosphate, and the free formaldehyde content of the low-free formaldehyde urea-formaldehyde resin is ≤0.1%.

5. The novel halogen-free phosphorus-nitrogen synergistic flame retardant for optical cable materials according to claim 4, characterized in that: The melamine derivative is melamine polyphosphate, and the mass ratio of low free formaldehyde urea-formaldehyde resin to melamine polyphosphate is 3.5:

1.

6. The novel halogen-free phosphorus-nitrogen synergistic flame retardant for optical cable materials according to claim 1, characterized in that: In the synergistic agent, the particle size of the nano-magnesium hydroxide is 50 nm to 100 nm, the organic modified montmorillonite is montmorillonite modified with a silane coupling agent, and the mass ratio of nano-magnesium hydroxide to organic modified montmorillonite is 1.5:

1.

7. The novel halogen-free phosphorus-nitrogen synergistic flame retardant for optical cable materials according to claim 1, characterized in that: The compatibility modifier is selected from one or two of silane coupling agents and maleic anhydride grafted polyethylene, and the mass ratio of the mixture is 1:1 to 1:

2.

8. The novel halogen-free phosphorus-nitrogen synergistic flame retardant for optical cable materials according to claim 1, characterized in that: The anti-exudant is selected from one or two of polyethylene glycol and polypropylene glycol, and the mass ratio of the mixture is 1:1 to 2:

1.

9. The novel halogen-free phosphorus-nitrogen synergistic flame retardant for optical cable materials according to claim 1, characterized in that: The heat stabilizer is selected from one or two of hindered phenolic antioxidants and phosphite antioxidants, and the mass ratio of the mixture is 1:1 to 1:

2.

10. The novel halogen-free phosphorus-nitrogen synergistic flame retardant for optical cable materials according to any one of claims 1-9, characterized in that: Its preparation method includes the following steps: Step S1: Pretreatment: Place the phosphorus-based flame retardant and the nitrogen-based flame retardant in a vacuum drying oven and dry them at 80 ℃~100℃ for 2 h~3 h to remove moisture and avoid agglomeration during the preparation process; perform surface activation treatment on the nano magnesium hydroxide in the synergistic agent, add 0.5%~1% of its mass of silane coupling agent KH-570, stir at 1000 r / min~1200 r / min in a high-speed mixer for 30 min~40 min, cool to room temperature for later use to improve its dispersibility and compatibility; Step S2: Mixing: Add the pretreated phosphorus-based flame retardant, nitrogen-based flame retardant, synergist, compatibility modifier, anti-exudation agent, and heat stabilizer to a high-speed mixer according to the above mass percentages. Mix for 30 min to 40 min at 80 ℃~90 ℃ and 1500 r / min~2000 r / min to ensure that each agent is uniformly dispersed and forms a mixture. Step S3: Melt extrusion: The mixture is fed into a twin-screw extruder, and the extrusion temperature is controlled at 160 ℃~180 ℃ and the screw speed is 200 r / min~300 r / min. Melting, mixing and extrusion are carried out, and the extruded material is cooled to room temperature by water cooling. Step S4: Crushing and Screening: The cooled extruded material is fed into a crusher for crushing. After crushing, it is screened through an 80-100 mesh screen to remove coarse particles and obtain the finished product of halogen-free phosphorus and nitrogen synergistic flame retardant for indoor optical cable materials.

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