Flame retardant containing microencapsulated red phosphorus and preparation method thereof

Abstract

The invention relates to the field of flame retardants, and discloses a flame retardant containing microencapsulated red phosphorus and a preparation method thereof. The invention discloses a flame retardant containing microencapsulated red phosphorus. The flame retardant is prepared from the following raw materials in percentage by weight: 45-55% of microencapsulated red phosphorus, 10-15% of melamine pyrophosphate and 35-45% of an inorganic flame retardant, the microencapsulated red phosphorus is prepared from red phosphorus, vinyl silicone resin, a cross-linking agent, an initiator, a pH regulator, a dispersant, an emulsifier and water through emulsion polymerization. The flame retardant containing microencapsulated red phosphorus prepared in the invention has the advantages of small usage amount, good stability after long-term storage, and difficult moisture absorption, has good flame resistance when being added into a heat shrink tube material with a small addition amount, and does not affect the mechanical properties of the heat shrink tube material.

Description

Technical Field

[0001] The present invention relates to the field of flame retardants, and more specifically, to a flame retardant containing microcapsule red phosphorus and a preparation method thereof. Background Art

[0002] Heat shrinkable materials are materials that can change their shape or restore them by heating. Low-density polyethylene (LDPE) and ethylene-vinyl acetate copolymer (EVA) are generally used as polymer materials. They are new materials that can be widely used in industries such as cable protection, pipeline transportation, and commodity packaging. High flame retardancy is an important performance indicator of heat shrinkable materials.

[0003] Red phosphorus, also known as red phosphorus, has the advantages of high phosphorus content and high flame retardant efficiency. However, red phosphorus is flammable in the air, easy to absorb moisture and oxidize, and its appearance is dark purple-red. For products with appearance requirements, it has certain limitations and is difficult to use directly as a flame retardant. Microencapsulation of red phosphorus can largely overcome the defects of red phosphorus. The prepared microencapsulated red phosphorus has good flame retardancy and flame retardant stability, and has good compatibility with polymer materials. It can be used in heat shrink tubing materials with high flame retardancy.

[0004] However, when using microcapsule red phosphorus alone as a flame retardant, a large amount needs to be added to achieve a good flame retardant effect, which is easy to affect the mechanical properties of the heat shrinkable tube material of the heat shrinkable tube, making the heat shrinkable tube easy to crack; if the microcapsule red phosphorus flame retardant and other flame retardants are added separately, although the flame retardancy of the prepared flame retardant can be improved and the amount of flame retardant used can be reduced, the operation process is relatively complicated and the processing efficiency is reduced. In order to solve the above problems, a hybrid flame retardant is prepared by mixing and compounding the microcapsule red phosphorus flame retardant with other flame retardants, but the hybrid flame retardant is prone to moisture absorption during storage, which reduces the flame retardant stability. Summary of the invention

[0005] In order to solve the problem that the mixed microcapsule red phosphorus flame retardant is easy to absorb moisture during long-term storage, thereby reducing the flame retardant stability, the present application provides a flame retardant containing microcapsule red phosphorus and a preparation method thereof.

[0006] In a first aspect, the present application provides a flame retardant containing microcapsule red phosphorus, which adopts the following technical solution: A flame retardant containing microcapsule red phosphorus is prepared from the following raw materials in percentage by weight: Microencapsulated red phosphorus 45-55% Melamine pyrophosphate 10-15% Inorganic flame retardant 35-45%; The microcapsule red phosphorus is prepared by emulsion polymerization of red phosphorus, vinyl silicone resin, a crosslinking agent, an initiator, a pH regulator, a dispersant, an emulsifier and water.

[0007] By adopting the above technical scheme, microcapsule red phosphorus is prepared by emulsion polymerization of red phosphorus, vinyl silicone resin, crosslinking agent, initiator, pH regulator, dispersant, emulsifier and water; water, emulsifier, dispersant and pH regulator form a stable emulsification system to improve the dispersibility of red phosphorus; vinyl silicone resin, crosslinking agent and initiator undergo free radical polymerization reaction in the emulsion system to form a crosslinked uniform and stable coating capsule wall on the surface of red phosphorus to coat the red phosphorus to prepare microcapsule red phosphorus, which has low hygroscopicity; when burning occurs, the microcapsule red phosphorus can be slowly released to achieve good flame retardancy; microcapsule red phosphorus is compounded with melamine pyrophosphate and inorganic flame retardant, the three have good synergistic effect, the prepared flame retardant has good stability, dispersibility and compatibility, is applied to heat shrink tube materials, can have good compatibility and dispersibility with the heat shrink tube materials, achieves good flame retardancy with a small amount, and does not affect the mechanical properties of the heat shrink tube materials.

[0008] Preferably, the microcapsule red phosphorus is prepared by the following steps: By weight, 5-10 parts of vinyl silicone resin, 1-3 parts of pH adjuster, 6-8 parts of emulsifier and 80-100 parts of water are added to a reaction device and stirred evenly to prepare an emulsion; Add 5-8 parts of dispersant to 30-40 parts of red phosphorus, grind, and prepare red phosphorus fine powder; The red phosphorus powder is added to the emulsion, and 3-5 parts of a cross-linking agent and 0.2-0.4 parts of an initiator are added to react, filtered, stirred and dried to obtain microcapsule red phosphorus.

[0009] By adopting the above technical scheme, the vinyl silicone resin is uniformly dispersed in an emulsified system formed by water, an emulsifier and a pH regulator to obtain an emulsion; under the dispersing and infiltration action of the dispersant, the red phosphorus is ground to form red phosphorus micropowder with uniform particle size, and at the same time, the dispersion uniformity and particle spacing between the red phosphorus micropowder particles are increased to improve the coating efficiency of the red phosphorus micropowder; the red phosphorus micropowder is added to the emulsion to fully disperse the red phosphorus micropowder in the emulsified system, and under the action of an initiator, the crosslinking agent and the vinyl silicone resin are emulsion polymerized to form a coated capsule wall on the surface of the red phosphorus, and finally, the microcapsule red phosphorus is filtered and stirred to dry, so that the microcapsule red phosphorus is uniformly dispersed, and microcapsule red phosphorus with a stable capsule wall coating is obtained.

[0010] Preferably, the emulsifier is composed of polyoxyethylene xylitol tristearate and alkylphenol polyoxyethylene ether ammonium sulfate in a weight ratio of 1:(1-3).

[0011] By adopting the above technical scheme, polyoxyethylene xylitol tristearate and alkylphenol polyoxyethylene ether ammonium sulfate in an optimal weight ratio are used as emulsifiers to form a stable emulsification system, thereby improving the dispersion stability of red phosphorus micropowder in the emulsification system and the stability of the emulsion polymerization reaction, thereby improving the stability of the prepared microcapsule red phosphorus.

[0012] Preferably, the cross-linking agent is composed of allyl glycidyl ether and pentaerythritol triallyl ether in a weight ratio of 1:(3-4).

[0013] By adopting the above technical scheme, allyl glycidyl ether and pentaerythritol triallyl ether in a preferred weight ratio are used as cross-linking agents, which can further undergo a cross-linking reaction with vinyl silicone resin to form a soft, interwoven network structure containing ether-based chain segments, which is coated on the surface of red phosphorus micropowder, thereby improving the stability of the prepared microcapsule red phosphorus, and further improving the flame retardant stability of the prepared flame retardant.

[0014] Preferably, the initiator is one or a combination of azobisisobutyronitrile, azobisisobutylamidine hydrochloride and azobisisobutylimidazoline hydrochloride.

[0015] By adopting the above technical solution, the above initiator has good initiation efficiency and can improve the efficiency of emulsion polymerization reaction.

[0016] Preferably, the vinyl silicone resin is vinyl MQ silicone resin and / or vinyl phenyl silicone resin.

[0017] By adopting the above technical scheme, the above vinyl silicone resin has excellent temperature resistance, flexibility, film-forming property, water resistance and bonding property, can form a uniform capsule wall on the surface of red phosphorus micropowder, and improve the stability of the prepared microcapsule red phosphorus.

[0018] Preferably, the dispersant is composed of tetrapolyricinoleate and a long-chain alkyl silane coupling agent in a weight ratio of (4-5):1.

[0019] By adopting the above technical scheme, tetrapolyricinoleate and long-chain alkyl silane coupling agent with a relatively optimal weight ratio are used as dispersants, so that the particle spacing of red phosphorus can be increased, the grinding efficiency of red phosphorus can be improved, and the coating efficiency of the prepared red phosphorus micropowder can be further improved; the long-chain alkyl silane coupling agent is a silane coupling agent containing eight to eighteen alkyl groups, has good flexibility and dispersibility, and can improve the coating performance of red phosphorus in the emulsion system.

[0020] Preferably, the particle size of the red phosphorus powder is 3-10 μm, and the thickness of the capsule wall of the microcapsule red phosphorus is 0.5-1.5 μm.

[0021] By adopting the above technical scheme, the red phosphorus powder with a better particle size has better particle size and dispersion uniformity. If the particle size of the red phosphorus powder is too small, the flame retardancy of the prepared microcapsule red phosphorus will be reduced. If the particle size of the red phosphorus powder is too large, it is not easy to be coated and the stability will be reduced. The capsule wall with a better thickness has better coating stability, reduces the easy moisture absorption of the microcapsule red phosphorus in the flame retardant, and is also easy to release slowly when burning, so as to achieve better flame retardant performance. If the capsule wall is too thick, the red phosphorus content will be reduced, thereby reducing the flame retardant performance of the flame retardant.

[0022] Preferably, the inorganic flame retardant is composed of aluminum hydroxide, magnesium hydroxide and zinc borate in a weight ratio of (1-2):(3-4):0.5.

[0023] By adopting the above technical scheme, aluminum hydroxide, magnesium hydroxide and zinc borate in an optimal weight ratio are used as inorganic flame retardants. When the flame retardant burns, it is easily thermally decomposed to absorb a large amount of heat. The decomposition product water vapor has the function of storing heat and diluting the concentration of combustible gas; it also forms a surface carbonization layer to prevent the entry of heat and oxygen, thereby achieving the purpose of flame retardancy; at the same time, microcapsule red phosphorus is dispersed in the inorganic flame retardant system, which can reduce the oxidation and hygroscopicity of the microcapsule red phosphorus and improve the stability of the prepared flame retardant.

[0024] In a second aspect, the present application provides a method for preparing a flame retardant containing microcapsule red phosphorus, using the following technical solution: A method for preparing a flame retardant containing microcapsule red phosphorus comprises the following steps: dispersing and uniformly mixing microcapsule red phosphorus, melamine pyrophosphate and an inorganic flame retardant to prepare the flame retardant containing microcapsule red phosphorus.

[0025] By adopting the technical scheme, a flame retardant containing microcapsule red phosphorus with uniform dispersion and stable system is prepared.

[0026] In summary, this application has the following beneficial effects: 1. The flame retardant containing microcapsule red phosphorus of the present application is compounded by microcapsule red phosphorus, melamine pyrophosphate and inorganic flame retardant. The three have good synergistic effect. The prepared flame retardant has good stability, dispersibility and compatibility, is not easy to absorb moisture, and is applied to heat shrinkable tube materials. It can have good compatibility and dispersibility with the heat shrinkable tube materials, achieve good flame retardant performance with less dosage, and will not affect the mechanical properties of the heat shrinkable tube materials.

[0027] 2. By using microcapsule red phosphorus prepared by emulsion polymerization of red phosphorus, vinyl silicone resin, crosslinking agent, initiator, pH adjuster, dispersant, emulsifier and water, water, emulsifier, dispersant and pH adjuster form a stable emulsification system to improve the dispersion performance of red phosphorus, vinyl silicone resin, crosslinking agent and initiator undergo polymerization reaction in the emulsion system to form a crosslinked uniform and stable coating capsule wall on the surface of red phosphorus to coat the red phosphorus and prepare microcapsule red phosphorus, which has low hygroscopicity. When burning occurs, the microcapsule red phosphorus can be slowly released to achieve good flame retardant performance.

[0028] 3. By using allyl glycidyl ether and pentaerythritol triallyl ether in a preferred weight ratio as crosslinking agents, it can further undergo crosslinking reaction with vinyl silicone resin to form a soft interwoven network structure containing ether chain segments, which is coated on the surface of red phosphorus micropowder, thereby improving the stability of the obtained microcapsule red phosphorus.

[0029] 4. By using tetrapolyricinoleate and long-chain alkyl silane coupling agent in an optimal weight ratio as dispersants, the particle spacing of red phosphorus can be increased, the grinding efficiency of red phosphorus can be improved, and the coating efficiency of the obtained red phosphorus micropowder can be further improved.

[0030] 5. By using polyoxyethylene xylitol tristearate and alkylphenol polyoxyethylene ether ammonium sulfate in a preferred weight ratio as emulsifiers, a stable emulsification system can be formed, which can improve the dispersion stability of red phosphorus micropowder in the emulsification system and the stability of the emulsion polymerization reaction, thereby improving the stability of the obtained microcapsule red phosphorus. DETAILED DESCRIPTION

[0031] The present application is further described in detail below with reference to the embodiments.

[0032] The following are the sources and specifications of some raw materials of this application. The raw materials used in the preparation examples and embodiments of this application can be obtained from the market, including but not limited to the raw materials of the following models and manufacturers. Raw materials with equivalent performance can be used: 1. Vinyl MQ silicone resin: Sihai SH-5202; 2. Vinylphenyl silicone resin: Lana White, vinyl content 5.4-5.6%; 3. Polyoxyethylene xylitol tristearate: Shenghe Chemical, content 99%; 4. Alkylphenol polyoxyethylene ether ammonium sulfate: Haian Petrochemical, CO436, content 60%; 5. Melamine pyrophosphate: melamine polyphosphate MPP, CAS No. 20208-95-1.

[0033] Preparation Example of Microencapsulated Red Phosphorus Preparation Example 1 Preparation Example 1 discloses a microcapsule red phosphorus, which is prepared by the following steps: 0.5 kg of vinyl silicone resin (composed of vinyl MQ silicone resin and vinyl phenyl silicone resin in a weight ratio of 3:1), 0.1 kg of 0.1 0.1 mol / L citric acid as a pH regulator, 0.6 kg of polyoxyethylene xylitol tristearate as an emulsifier, and 8 kg of water were added to a reactor, and the stirring rate was halved for 60 min under a stirring rate of 500 r / min to obtain an emulsion; 0.5 kg of a dispersant (composed of glycerol and vinyl trimethoxysilane in a weight ratio of 2:1) was added to 3 kg of red phosphorus, and ground for 2 h to obtain red phosphorus micropowder with a particle size of 3-10 μm; The red phosphorus powder was added to the emulsion, and 0.5 kg of glycidyl methacrylate was added as a cross-linking agent and 0.02 kg of azobisisobutyronitrile was added as an initiator for reaction. The reaction temperature was controlled at 60°C and the reaction time was 3 h. The mixture was filtered and then dispersed and dried at a stirring rate of 500 r / min to obtain microcapsule red phosphorus with a capsule wall thickness of 0.5 μm.

[0034] Preparation Example 2-3 The difference between Preparation Example 2-3 and Preparation Example 1 is that the amount of raw materials used and the preparation conditions are different, see Table 1 below for details.

[0035] Table 1 Raw material dosage and preparation conditions of Preparation Examples 1-3 Preparation Example 4 The difference between Preparation Example 4 and Preparation Example 1 is that the emulsifier is different. The emulsifier in Preparation Example 4 is composed of polyoxyethylene xylitol tristearate and alkylphenol polyoxyethylene ether ammonium sulfate in a weight ratio of 1:1, and the rest is the same as Preparation Example 1.

[0036] Preparation Example 5 The difference between Preparation Example 5 and Preparation Example 1 is that the emulsifier in Preparation Example 5 is composed of polyoxyethylene xylitol tristearate and alkylphenol polyoxyethylene ether ammonium sulfate in a weight ratio of 1:3, and the rest is the same as Preparation Example 1.

[0037] Preparation Example 6 The difference between Preparation Example 6 and Preparation Example 5 is that the dispersant is different. The dispersant in Preparation Example 6 is composed of tetrapolyricinoleate and a long-chain alkyl silane coupling agent in a weight ratio of 4:1, and the long-chain alkyl silane coupling agent is dodecyltrimethoxysilane. The rest is the same as Preparation Example 5.

[0038] Preparation Example 7 The difference between Preparation Example 7 and Preparation Example 5 is that the dispersant in Preparation Example 7 is composed of tetrapolyricinoleate and a long-chain alkyl silane coupling agent in a weight ratio of 5:1, the long-chain alkyl silane coupling agent is dodecyltrimethoxysilane, and the rest is the same as Preparation Example 5.

[0039] Preparation Example 8 The difference between Preparation Example 8 and Preparation Example 6 is that the cross-linking agent is different. The cross-linking agent in Preparation Example 8 is composed of allyl glycidyl ether and pentaerythritol triallyl ether in a weight ratio of 1:3, and the rest is the same as Preparation Example 6.

[0040] Preparation Example 9 The difference between Preparation Example 9 and Preparation Example 6 is that the cross-linking agent in Preparation Example 9 is composed of allyl glycidyl ether and pentaerythritol triallyl ether in a weight ratio of 1:4, and the rest is the same as Preparation Example 6.

[0041] Preparation Example 10 The difference between Preparation Example 10 and Preparation Example 6 is that the cross-linking agent in Preparation Example 10 is composed of glycidyl methacrylate and allyl glycidyl ether in a weight ratio of 1:3, and the rest is the same as Preparation Example 6. Example

[0042] Example 1 Example 1 discloses a flame retardant containing microcapsule red phosphorus, which is prepared by the following steps: grinding melamine pyrophosphate and an inorganic flame retardant to a particle size of 5-10 μm, then dispersing and evenly mixing 5.5 kg of microcapsule red phosphorus prepared in Preparation Example 1, 1 kg of melamine pyrophosphate and 3.5 kg of inorganic flame retardant (composed of aluminum hydroxide, magnesium hydroxide and zinc borate in a weight ratio of 1:3:0.5) to obtain a flame retardant containing microcapsule red phosphorus.

[0043] Example 2-3 The difference between Example 2-3 and Example 1 is that the amount of raw materials used and the preparation conditions are different, see Table 2 below for details.

[0044] Table 2 Parameters of Examples 1-3 Embodiment 4-10 The difference between Examples 4-10 and Example 1 is that the sources of the microcapsule red phosphorus are different, see Table 3 below for details.

[0045] Table 3 Sources of microcapsule red phosphorus in Examples 4-10 Example Microencapsulated Red Phosphorus Sources Table Example 4 Preparation Example 4 Example 5 Preparation Example 5 Example 6 Preparation Example 6 Example 7 Preparation Example 7 Example 8 Preparation Example 8 Example 9 Preparation Example 9 Example 10 Preparation Example 10 Comparative Example Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the microcapsule red phosphorus in Comparative Example 1 comes from commercially available Cassource New Materials, KSYA-2568, and has a phosphorus content of 45-50%. The rest is the same as Example 1.

[0046] Performance Test The flame retardants containing microcapsule red phosphorus prepared in Examples 1-10 and Comparative Example 1 were tested for their performance: 1. Hygroscopicity test: Weigh a certain amount of flame retardant, record it as m1, place the flame retardant under the condition of humidity of 55% and temperature of 30℃ for 48h, weigh it, record it as m2, hygroscopicity is expressed by moisture absorption rate (unit: %), moisture absorption rate = (m2-m1) / m1*100%, record the test results; 2. Flame retardant performance test: 0.5 kg of flame retardant and 9.5 kg of EVA resin were injection molded, and the EVA material was commercially available Arkema EVA28-800, to make a test strip; referring to the test method in GB / T 2406, the limiting oxygen index (unit: %) of the test strip was tested, and the test results were recorded; 3. Tensile strength test 0.5 kg of flame retardant and 9.5 kg of EVA resin were injection molded, and the EVA material was commercially available Arkema EVA28-800, and made into test strips. The tensile strength (unit: MPa) of the test strips was tested using a tensile testing machine, and the test results were recorded; The following are the performance test data of the flame retardant containing microcapsule red phosphorus of Examples 1-10 and Comparative Example 1, see Table 4 below for details.

[0047] Table 4 Performance test data of Examples 1-10 and Comparative Example 1 Combining Examples 1-3 and Comparative Example 1 and Table 4, it can be concluded that the flame retardant prepared using the microcapsule red phosphorus of the present application has low hygroscopicity, and adding 5% can achieve good flame retardancy without affecting the mechanical properties of the heat shrinkable tube material; Compared with Example 1, Comparative Example 1 uses commercially available microcapsule red phosphorus, and the moisture absorption rate is increased by 1.37%. When applied to the heat shrinkable tube material, the limiting oxygen index is reduced by 1.9%, and the tensile strength is reduced by 1.6 MPa.

[0048] Combining Example 1 and Examples 4-5 and Table 4, it can be concluded that by optimizing the emulsifier, the stability and flame retardancy of the flame retardant prepared can be improved; compared with Example 1, the performance of the flame retardant prepared in Examples 4-5 is improved.

[0049] Combining Example 5 and Examples 6-7 with Table 4, it can be concluded that by optimizing the dispersant, the stability and flame retardancy of the flame retardant prepared can be improved; compared with Example 5, the performance of the flame retardant prepared in Examples 6-7 is improved.

[0050] In combination with Example 6 and Examples 8-10 and Table 4, it can be concluded that further optimizing the cross-linking agent of the present application can play a good synergistic role with the emulsifier and the dispersant, thereby improving the stability and flame retardancy of the flame retardant obtained; the moisture absorption rate of the flame retardant obtained in Example 8 is only 0.38%, and when applied to heat shrinkable tube materials, the limiting oxygen index is increased to 30.5%, and the tensile strength can also reach 8.7MPa.

[0051] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A flame retardant containing microcapsule red phosphorus, characterized in that: Made from the following raw materials in weight percentage: Microencapsulated red phosphorus 45-55% Melamine pyrophosphate 10-15% Inorganic flame retardant 35-45%; The microcapsule red phosphorus is prepared by emulsion polymerization of red phosphorus, vinyl silicone resin, a crosslinking agent, an initiator, a pH regulator, a dispersant, an emulsifier and water.

2. A flame retardant containing microcapsule red phosphorus according to claim 1, characterized in that: The microcapsule red phosphorus is prepared by the following steps: By weight, 5-10 parts of vinyl silicone resin, 1-3 parts of pH adjuster, 6-8 parts of emulsifier and 80-100 parts of water are added to a reaction device and stirred evenly to prepare an emulsion; Add 5-8 parts of dispersant to 30-40 parts of red phosphorus, grind, and prepare red phosphorus fine powder; The red phosphorus powder is added to the emulsion, and 3-5 parts of a cross-linking agent and 0.2-0.4 parts of an initiator are added to react, filtered, stirred and dried to obtain microcapsule red phosphorus.

3. A flame retardant containing microcapsule red phosphorus according to claim 2, characterized in that: The emulsifier is composed of polyoxyethylene xylitol tristearate and alkylphenol polyoxyethylene ether ammonium sulfate in a weight ratio of 1:(1-3).

4. A flame retardant containing microcapsule red phosphorus according to claim 2, characterized in that: The cross-linking agent is composed of allyl glycidyl ether and pentaerythritol triallyl ether in a weight ratio of 1:(3-4).

5. A flame retardant containing microcapsule red phosphorus according to claim 2, characterized in that: The initiator is one or a combination of azobisisobutyronitrile, azobisisobutylamidine hydrochloride and azobisisobutylimidazoline hydrochloride.

6. A flame retardant containing microcapsule red phosphorus according to claim 2, characterized in that: The vinyl silicone resin is vinyl MQ silicone resin and / or vinyl phenyl silicone resin.

7. A flame retardant containing microcapsule red phosphorus according to claim 2, characterized in that: The dispersant is composed of tetrapolyricinoleic acid ester and a long-chain alkyl silane coupling agent in a weight ratio of (4-5):

1.

8. A flame retardant containing microcapsule red phosphorus according to any one of claims 1 to 7, characterized in that: The particle size of the red phosphorus powder is 3-10 μm, and the thickness of the capsule wall of the microcapsule red phosphorus is 0.5-1.5 μm.

9. A flame retardant containing microcapsule red phosphorus according to claim 1, characterized in that: The inorganic flame retardant is composed of aluminum hydroxide, magnesium hydroxide and zinc borate in a weight ratio of (1-2): (3-4): 0.

5.

10. A method for preparing a flame retardant containing microcapsule red phosphorus according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: dispersing and uniformly mixing microcapsule red phosphorus, melamine pyrophosphate and an inorganic flame retardant to prepare a flame retardant containing microcapsule red phosphorus.

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