A PVC flame retardant smoke suppressant and preparation method thereof

Abstract

The present invention relates to the technical field of flame retardant and smoke suppression of polyvinyl chloride materials, and specifically discloses a PVC flame retardant and smoke suppression agent and a preparation method thereof. A preparation method of a PVC flame retardant and smoke suppression agent comprises first mixing 100 parts of water, 15-20 parts of nano magnesium hydroxide, 5-10 parts of nano silicon dioxide, 7-9 parts of triethyl phosphate, 2-5 parts of polypropylene glycol monobutyl ether, and 1-3 parts of soybean lecithin to obtain a nano dispersion; then mixing the nano dispersion and EVA latex in a certain proportion and stirring evenly to obtain an emulsion mixture; finally, vacuum degassing the emulsion mixture, spray drying, and sieving to obtain a PVC flame retardant and smoke suppression agent. The PVC flame retardant and smoke suppression agent prepared in the present application not only has excellent flame retardant and smoke suppression performance, but also has good dispersibility and compatibility, and can effectively improve the flame retardant and smoke suppression performance of the PVC material without affecting the comprehensive performance of the PVC material.

Description

Technical Field

[0001] The invention relates to the technical field of flame retardant and smoke suppression of polyvinyl chloride materials, in particular to a PVC flame retardant and smoke suppression agent and a preparation method thereof. Background Art

[0002] With the advancement of science and technology and the improvement of environmental awareness, PVC (polyvinyl chloride) materials are widely used in the fields of wires and cables, building materials, medical devices, etc. due to their excellent physical properties and processing properties. However, in actual applications, a large amount of plasticizers need to be added to PVC materials to improve their softness, which leads to a decrease in the flame retardant properties of PVC materials. In addition, since PVC materials themselves contain a large number of chlorine atoms, a large amount of smoke and toxic gases will be generated when they burn, posing a serious threat to the environment and human health. Therefore, it is necessary to improve the flame retardancy and smoke suppression of PVC materials.

[0003] At present, the flame retardant and smoke suppressant is usually added to the PVC material to achieve the effect of improving the flame retardancy and smoke suppression of PVC materials. Common flame retardants and smoke suppressants on the market can be divided into two categories: inorganic flame retardants and organic flame retardants. Among them, inorganic flame retardants mainly include aluminum, silicon, boron, etc. However, traditional inorganic flame retardants often have problems such as large addition amount, poor dispersibility, and poor compatibility with PVC materials when used, resulting in poor flame retardancy and smoke suppression effects, and easily affecting the comprehensive performance of PVC materials, which seriously limits the application of inorganic flame retardants in PVC materials. Existing studies have shown that the preparation of nano-scale inorganic flame retardants can increase the interface contact between inorganic flame retardants and PVC materials, and can effectively improve the flame retardancy of PVC materials at a lower addition amount, thereby effectively reducing the addition amount of inorganic flame retardants and reducing the impact of inorganic flame retardants on the comprehensive performance of PVC materials. However, when nano-scale inorganic flame retardants are added to PVC materials, due to the large surface area and high surface energy of nano-scale inorganic flame retardants, the nano-scale inorganic flame retardants are easily attracted to each other and easily agglomerated to form large particle agglomerates, thereby losing the advantages of nanoparticles, resulting in the flame retardancy of PVC materials being not significantly improved. At the same time, the large particle agglomerates formed will destroy the molecular structure of the PVC material itself, resulting in a decrease in the comprehensive performance of the PVC material. In view of the above problems, it is necessary to provide a new flame retardant and smoke suppressant that is not easy to agglomerate and has good dispersibility in PVC materials. Summary of the invention

[0004] In order to solve the technical problem that nano-scale inorganic flame retardants are prone to agglomeration, the present application provides a PVC flame retardant and smoke suppressant and a preparation method thereof. The present application found in the research that by mixing nano-magnesium hydroxide and nano-silicon dioxide, preparing a specific nano-dispersion liquid, and embedding nano-magnesium hydroxide and silicon dioxide with EVA latex, the dispersibility and compatibility of nano-scale inorganic flame retardants in PVC materials can be effectively improved, thereby significantly improving the flame retardant and smoke suppression properties of PVC materials while ensuring good comprehensive performance of PVC materials.

[0005] Specifically, the preparation method of a PVC flame retardant and smoke suppressant provided in the present application adopts the following technical scheme:

[0006] A method for preparing a PVC flame retardant and smoke suppressant comprises the following steps:

[0007] Step 1: Mix 100 parts of water, 15-20 parts of nano magnesium hydroxide, 5-10 parts of nano silicon dioxide, 7-9 parts of triethyl phosphate, 2-5 parts of polypropylene glycol monobutyl ether, and 1-3 parts of soybean lecithin, heat to 50-60° C., stir and disperse evenly to obtain a nano dispersion;

[0008] Step 2: Mix the nano-dispersion liquid and EVA latex in a certain proportion and stir evenly to obtain an emulsion mixture;

[0009] Step 3: The emulsion mixture is subjected to vacuum degassing, spray drying and sieving to obtain a PVC flame retardant and smoke suppressant.

[0010] In the above technical scheme, the present application prepares a specific nano-dispersion liquid, utilizes a mixture of nano-magnesium hydroxide and nano-silicon dioxide, uses triethyl phosphate and polypropylene glycol monobutyl ether as surface modifiers, and soybean lecithin as a dispersant. The three work together to enable nano-magnesium hydroxide and nano-silicon dioxide to be evenly dispersed in the aqueous phase, avoiding the occurrence of agglomeration, and forming a stable nano-dispersion liquid. At the same time, the present application has found in the study that the mutual cooperation of triethyl phosphate, polypropylene glycol monobutyl ether and soybean lecithin can also significantly improve the flame retardant and smoke suppression effect of PVC flame retardant and smoke suppressant. This is because triethyl phosphate can release phosphate ions at high temperature, capture free radicals produced by combustion, and thus inhibit the combustion reaction. Triethyl phosphate, polypropylene glycol monobutyl ether and soybean lecithin have good surface modification effects and can be wrapped on the surface of nano-magnesium hydroxide and nano-silicon dioxide to form a protective film, further reducing the possibility of direct contact between nanoparticles and PVC materials, further reducing the damage of nanoparticles to the molecular structure of PVC materials, and maintaining the comprehensive performance of PVC materials. Triethyl phosphate, polypropylene glycol monobutyl ether and soybean lecithin act on PVC flame retardant and smoke suppressant from different mechanisms, thereby achieving the improvement of flame retardant and smoke suppression performance and the maintenance of comprehensive performance of PVC materials.

[0011] The present application further uses EVA latex as an embedding agent, and through the good surface modification effect of triethyl phosphate, polypropylene glycol monobutyl ether, and soybean lecithin, the nanoparticles in the nanodispersion are uniformly coated in the EVA latex particles to form an emulsion mixture. This embedding structure enables the nanoparticles to have good dispersibility and compatibility in the PVC material, thereby significantly improving the flame retardant and smoke suppression properties of the PVC material while ensuring the good comprehensive performance of the PVC material.

[0012] Preferably, the solid content of the EVA latex in step 2 is 50-60%, and the emulsion mixture includes 15-20 parts of nano-dispersion and 6-8 parts of EVA latex, based on the mass fraction.

[0013] In the above technical scheme, the present application selects the solid content of EVA latex so that the nanoparticles in the emulsion mixture can be better coated to form a uniform embedding structure. The present application can ensure the stability and fluidity of the emulsion mixture while ensuring the effective coating of the nanoparticles, which is convenient for subsequent processing and application.

[0014] Preferably, 1-2 portions of carbon nanotubes are also added in step 2.

[0015] In the above technical solution, the present application can further enhance the flame retardant and smoke suppression performance of the PVC flame retardant and smoke suppressant by adding carbon nanotubes, utilizing their high specific surface area and good electrical conductivity. At the same time, the addition of carbon nanotubes can also improve the mechanical properties and thermal stability of PVC materials, further improving the comprehensive performance of PVC materials.

[0016] Preferably, in step 2, 0.1-0.2 parts of silane coupling agent and 0.1-0.2 parts of polyvinyl pyrrolidone are also added.

[0017] In the above technical solution, the present application further improves the interfacial compatibility between nanoparticles and EVA latex by adding silane coupling agent and polyvinyl pyrrolidone, and enhances the dispersibility and stability of nanoparticles in PVC materials. Silane coupling agent, as a commonly used interfacial modifier, can effectively improve the interfacial compatibility between carbon nanotubes and other materials, while polyvinyl pyrrolidone, as a surfactant, has good dispersibility and wettability, and can further improve the dispersibility of nanoparticles, especially carbon nanotubes, in the emulsion mixture, and improve the uniformity and stability of the flame retardant and smoke suppressant.

[0018] Preferably, the stirring and dispersing uniformly in step 1 means first stirring at 200-500 r / min for 10-15 min, then emulsifying at 2000-3000 r / min for 50-60 min, and finally ultrasonically treating at 20-25 KHz for 15-20 min to obtain a nano-dispersion liquid.

[0019] Preferably, the uniform stirring in step 2 refers to continuous stirring at 2000-2500 r / min until the two are uniformly mixed to obtain an emulsion mixture.

[0020] In the above technical scheme, the present application ensures the uniform dispersion of nano-magnesium hydroxide and nano-silicon dioxide in the nano-dispersion liquid and the complete encapsulation of nano-particles by nano-EVA latex by optimizing the stirring speed and stirring time and adopting ultrasonic treatment.

[0021] Preferably, the particle size of the nano magnesium hydroxide is 50-100 nm, and the particle size of the nano silicon dioxide is 50-100 nm.

[0022] In the above technical scheme, the present application selects nano magnesium hydroxide and nano silicon dioxide of specific particle size, and through the matching of the particle size of these two nano materials, ensures that the nanoparticles have better dispersibility and compatibility in the PVC material, avoids uneven dispersion and agglomeration caused by excessive difference in particle size, and further enhances the performance of the flame retardant and smoke suppressant.

[0023] Preferably, the screening in step 3 refers to screening out PVC flame retardant and smoke suppressant particles with a particle size of 300-1000 nm.

[0024] In the above technical solution, the present application screens out the PVC flame retardant and smoke suppressant particles with a particle size of 300-1000nm through screening, thereby ensuring the uniformity and consistency of the flame retardant and smoke suppressant particles. This step helps to maintain the stability and uniformity of the flame retardant and smoke suppressant particles in subsequent processing and application, thereby ensuring the continuous and reliable flame retardant and smoke suppression performance of the PVC material.

[0025] Preferably, the vacuum degassing treatment in step 3 refers to degassing the emulsion mixture under a vacuum degree of -0.08 to -0.1 MPa.

[0026] In the above technical solution, the gas in the emulsion mixture can be removed by degassing the emulsion mixture, thereby preventing the gas from forming bubbles in the subsequent processing and affecting the preparation effect of the PVC flame retardant and smoke suppressant.

[0027] Preferably, the spray drying in step 3 is to place the emulsion mixture in a nano spray dryer at a temperature of 120-150°C and an air volume of 0.5-1.0 m 3 The spray drying was carried out under the condition of 1000 rpm.

[0028] In the above technical solution, spray drying is carried out under the above conditions, which can ensure that the solvent in the emulsion mixture evaporates quickly to form PVC flame retardant and smoke suppressant particles with uniform particle size, thereby maintaining its good flame retardant and smoke suppression properties.

[0029] The present application also provides a PVC flame retardant smoke suppressant, which adopts the following technical solution:

[0030] A PVC flame retardant and smoke suppressant, characterized in that it is prepared by the preparation method of the PVC flame retardant and smoke suppressant provided in the present application.

[0031] In the above technical scheme, the PVC flame retardant and smoke suppressant prepared in the present application not only has excellent flame retardant and smoke suppression properties, but also has good dispersibility and compatibility, and can effectively improve the flame retardant and smoke suppression properties of PVC materials without affecting the comprehensive performance of PVC materials.

[0032] In summary, the present application includes at least one of the following beneficial technical effects:

[0033] 1. The present application, through the mixing of nano-magnesium hydroxide and nano-silicon dioxide, the mutual coordination of triethyl phosphate, polypropylene glycol monobutyl ether and soybean lecithin, and the embedding effect of EVA latex, can effectively solve the problem of easy agglomeration of nano-scale inorganic flame retardants, improve the dispersibility and compatibility of flame retardants and smoke suppressants in PVC materials, thereby significantly improving the flame retardant and smoke suppression properties of PVC materials while ensuring good comprehensive performance of PVC materials.

[0034] 2. This application further adds carbon nanotubes, silane coupling agents, and polyvinyl pyrrolidone, which not only ensures that the nanoparticles can be evenly coated in the EVA latex particles, but also further enhances the flame retardant and smoke suppression properties of the PVC flame retardant and smoke suppressant. DETAILED DESCRIPTION

[0035] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0036] Example 1

[0037] A method for preparing a PVC flame retardant and smoke suppressant comprises the following steps:

[0038] Step 1: Mix 100 kg of water, 15 kg of nano-magnesium hydroxide, 10 kg of nano-silicon dioxide, 9 kg of triethyl phosphate, 2 kg of polypropylene glycol monobutyl ether, and 3 kg of soybean lecithin, heat to 50°C, stir continuously at 200 r / min for 15 min, emulsify at 2000 r / min for 60 min, and finally ultrasonically treat at 20 kHz for 20 min to obtain a nano-dispersion.

[0039] Step 2: Take 15 kg of nano-dispersion and 6 kg of EVA latex, and stir them continuously at 2000 r / min until the two are evenly mixed to obtain an emulsion mixture.

[0040] Step 3: After degassing the emulsion mixture under vacuum of -0.08 MPa, place it in a nano spray dryer at a temperature of 120°C and an air volume of 0.5 m 3 The spray drying is carried out under the condition of 10000 g / min, and then the PVC flame retardant and smoke suppressant with a particle size of 300-1000 nm is sieved out.

[0041] The particle size of nano magnesium hydroxide is 50-100 nm, and the particle size of nano silicon dioxide is 50-100 nm.

[0042] Among them, triethyl phosphate was purchased from Shandong Maofa Chemical Co., Ltd.

[0043] Among them, polypropylene glycol monobutyl ether was purchased from Hubei Shineng Chemical Technology Co., Ltd.

[0044] Among them, soybean lecithin was purchased from Guangdong Mingtong Biotechnology Co., Ltd.

[0045] Among them, EVA latex was purchased from Changzhou Modern Chemical Co., Ltd. with a solid content of 52%.

[0046] Example 2

[0047] A method for preparing a PVC flame retardant and smoke suppressant, which is different from Example 1, comprises the following steps:

[0048] Step 1: Mix 100 kg of water, 20 kg of nano-magnesium hydroxide, 5 kg of nano-silicon dioxide, 7 kg of triethyl phosphate, 5 kg of polypropylene glycol monobutyl ether, and 1 kg of soybean lecithin, heat to 60°C, stir continuously at 500 r / min for 10 min, then emulsify at 3000 r / min for 50 min, and finally ultrasonically treat at 25 kHz for 15 min to obtain a nano-dispersion.

[0049] Step 2: Take 20 kg of nano-dispersion and 8 kg of EVA latex, and continue stirring at 2500 r / min until the two are evenly mixed to obtain an emulsion mixture.

[0050] Step 3: After degassing the emulsion mixture under vacuum of -0.1 MPa, place it in a nano spray dryer at a temperature of 150°C and an air volume of 1.0 m 3 The spray drying is carried out under the condition of 10000 g / min, and then the PVC flame retardant and smoke suppressant with a particle size of 300-1000 nm is sieved out.

[0051] Example 3

[0052] A method for preparing a PVC flame retardant and smoke suppressant, which is different from Example 1, comprises the following steps:

[0053] Step 1: Mix 100 kg of water, 18 kg of nano-magnesium hydroxide, 8 kg of nano-silicon dioxide, 8 kg of triethyl phosphate, 4 kg of polypropylene glycol monobutyl ether, and 2 kg of soybean lecithin, heat to 55°C, stir continuously at 400 r / min for 12 min, emulsify at 2500 r / min for 55 min, and finally ultrasonically treat at 22 kHz for 18 min to obtain a nano-dispersion.

[0054] Step 2: Take 18 kg of nano-dispersion and 7 kg of EVA latex, and continue stirring at 2200 r / min until the two are mixed evenly to obtain an emulsion mixture.

[0055] Step 3: After degassing the emulsion mixture under vacuum of -0.09 MPa, place it in a nano spray dryer at a temperature of 130°C and an air volume of 0.7 m 3 The spray drying is carried out under the condition of 10000 g / min, and then the PVC flame retardant and smoke suppressant with a particle size of 300-1000 nm is sieved out.

[0056] Example 4

[0057] A method for preparing a PVC flame retardant and smoke suppressant, which is different from Example 1 in that nano carbon tubes, a silane coupling agent and polyvinyl pyrrolidone are also added in step 2.

[0058] Among them, the specific steps of step 2 are as follows:

[0059] Take 6 kg of EVA latex, add 1 kg of carbon nanotubes, 0.2 kg of silane coupling agent, and 0.1 kg of polyvinyl pyrrolidone, and continue stirring at 2000 r / min until the two are evenly mixed, then add 15 kg of nano-dispersion liquid, and continue stirring at 2000 r / min until the two are evenly mixed to obtain an emulsion mixture.

[0060] Among them, the carbon nanotubes were purchased from Guangzhou Hongwu Material Technology Co., Ltd., with a length of 30-60nm and a diameter of 2nm.

[0061] The silane coupling agent is silane coupling agent KH560 purchased from Jinan Dehou Chemical Co., Ltd.

[0062] Among them, polyvinyl pyrrolidone is polyvinyl pyrrolidone PVP purchased from Nanjing Ruize Fine Chemical Co., Ltd.

[0063] Example 5

[0064] A method for preparing a PVC flame retardant and smoke suppressant, which is different from Example 1 in that nano carbon tubes, a silane coupling agent and polyvinyl pyrrolidone are also added in step 2.

[0065] Among them, the specific steps of step 2 are as follows:

[0066] Take 6 kg of EVA latex, add 2 kg of carbon nanotubes, 0.1 kg of silane coupling agent, and 0.2 kg of polyvinyl pyrrolidone, and continue stirring at 2000 r / min until the two are evenly mixed, then add 15 kg of nano-dispersion liquid, and continue stirring at 2000 r / min until the two are evenly mixed to obtain an emulsion mixture.

[0067] Example 6

[0068] A method for preparing a PVC flame retardant and smoke suppressant, which is different from Example 4 in that no silane coupling agent and polyvinyl pyrrolidone are added in step 2.

[0069] Comparative Example 1

[0070] A method for preparing a PVC flame retardant and smoke suppressant, which is different from Example 1 in that in step 1, an equal amount of triethyl phosphate is replaced by a silane coupling agent KH560.

[0071] Comparative Example 2

[0072] A method for preparing a PVC flame retardant and smoke suppressant, which is different from Example 1 in that in step 1, an equal amount of polypropylene glycol monobutyl ether is replaced by polyethylene glycol distearate.

[0073] Comparative Example 3

[0074] A method for preparing a PVC flame retardant and smoke suppressant, which is different from Example 1 in that in step 1, an equal amount of soybean lecithin is replaced by polyethylene glycol distearate.

[0075] Comparative Example 4

[0076] A method for preparing a PVC flame retardant and smoke suppressant, which is different from Example 1 in that step 3 is specifically as follows:

[0077] The emulsion mixture is degassed under a vacuum degree of -0.08 MPa, dried, and then crushed into a PVC flame retardant and smoke suppressant with a particle size of 300-1000 nm.

[0078] Verification test

[0079] Test 1, Stability evaluation of nanodispersion:

[0080] Sample: Nano-dispersion prepared in Examples 1-3 and Comparative Examples 1-3.

[0081] Test method: The nano-dispersion was placed at 50°C for 1 month, and the changes before and after storage were observed. The results are shown in Table 1.

[0082] Table 1:

[0083] Group Changes Example 1 The nanodispersion liquid has no change compared with before storage Example 2 The nanodispersion liquid has no change compared with before storage Example 3 The nanodispersion liquid has no change compared with before storage Comparative Example 1 Compared with the nano-dispersion before storage, there is some precipitation Comparative Example 2 Compared with the nano-dispersion before storage, there is some precipitation Comparative Example 3 Compared with the nano-dispersion before storage, there is some precipitation

[0084] Combining the analysis of Examples 1-3, Comparative Examples 1-3 and Table 1, it is not difficult to see that the combination of triethyl phosphate, polypropylene glycol monobutyl ether and soybean lecithin can be used to prepare a nano-dispersion with good stability. It can be seen that the combination of triethyl phosphate, polypropylene glycol monobutyl ether and soybean lecithin selected in this application has a particularity. The three cooperate with each other and can well participate in the surface modification of nanoparticles, promote the uniform dispersion of nanoparticles in the aqueous phase, and enhance the stability of the nano-dispersion.

[0085] Test 2, evaluation of flame retardant and smoke suppression performance of PVC flame retardant and smoke suppression agent:

[0086] Sample: PVC flame retardant and smoke suppressant prepared in Examples 1-6 and Comparative Examples 1-4.

[0087] Test method: PVC flame retardant and smoke suppressant agent and soft PVC material were blended and melted in a mass ratio of 1:10, and a PVC flame retardant and smoke suppressant composite material was prepared by a torque rheometer.

[0088] Oxygen index: tested according to GB / T2406-2009 standard, the sample standard is 130mm*6.5mm*3mm.

[0089] Smoke density: tested according to ISO5660 standard, the sample standard is 10mm*10mm*4mm.

[0090] Tensile strength: tested according to GB / T528-2009 standard, the tensile speed is 50mm / min.

[0091] The above test results are shown in Table 2.

[0092] Table 2:

[0093]

[0094]

[0095] Combining the data of Examples 1-6, Comparative Examples 1-4 and Table 2, we can analyze that the flame retardant and smoke suppression agent of PVC prepared in this application has significantly improved flame retardant and smoke suppression performance compared with the comparative example. In Examples 4 and 5, after adding carbon nanotubes, silane coupling agent and polyvinyl pyrrolidone, the flame retardant and smoke suppression performance is further improved.

[0096] A specific analysis of the PVC flame retardant and smoke suppressant of Example 1 and Comparative Examples 1-3 shows that the flame retardant and smoke suppressant of Example 1 has good flame retardant and smoke suppressant properties, which verifies the superiority of the combination of triethyl phosphate, polypropylene glycol monobutyl ether and soybean lecithin used in the present application in the preparation of nano-dispersions and PVC flame retardant and smoke suppressant. The present application can prepare a PVC flame retardant and smoke suppressant with good flame retardant and smoke suppressant properties by selecting a combination of triethyl phosphate, polypropylene glycol monobutyl ether and soybean lecithin. The cooperation of triethyl phosphate, polypropylene glycol monobutyl ether and soybean lecithin can not only further improve the dispersibility of nanoparticles, enhance the embedding effect of EVA latex on nanoparticles, enhance the compatibility of PVC flame retardant and smoke suppressant with PVC, but also further improve the flame retardant and smoke suppressant properties of PVC flame retardant and smoke suppressant.

[0097] A specific analysis of the PVC flame retardant and smoke suppressant of Example 1 and Comparative Example 4 shows that there is a difference in their flame retardant and smoke suppressant properties. This is because the preparation process of Comparative Example 4 lacks the spray drying step, which makes the dispersibility and particle size control of the nanoparticles inferior to the samples prepared by the spray drying method.

[0098] 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 method for preparing a PVC flame retardant and smoke suppressant, characterized in that: The following steps are involved: Step 1: Mix 100 parts of water, 15-20 parts of nano magnesium hydroxide, 5-10 parts of nano silicon dioxide, 7-9 parts of triethyl phosphate, 2-5 parts of polypropylene glycol monobutyl ether, and 1-3 parts of soybean lecithin, heat to 50-60° C., stir and disperse evenly to obtain a nano dispersion; Step 2: Mix the nano-dispersion liquid and EVA latex in a certain proportion and stir evenly to obtain an emulsion mixture; Step 3: vacuum degassing the emulsion mixture, spray drying it and then sieving it to obtain a PVC flame retardant and smoke suppressant; The solid content of the EVA latex in step 2 is 50-60%, based on the mass fraction of the emulsion mixture, including 15-20 parts of the nano-dispersion and 6-8 parts of the EVA latex; In step 2, 1-2 portions of carbon nanotubes are also added; In the step 2, 0.1-0.2 parts of silane coupling agent and 0.1-0.2 parts of polyvinyl pyrrolidone are also added.

2. The method for preparing a PVC flame retardant and smoke suppressant according to claim 1, characterized in that: The stirring and dispersing uniformly in step 1 means first stirring at 200-500 r / min for 10-15 min, then emulsifying at 2000-3000 r / min for 50-60 min, and finally ultrasonically treating at 20-25 KHz for 15-20 min to obtain a nano-dispersion liquid.

3. The method for preparing a PVC flame retardant and smoke suppressant according to claim 1, characterized in that: The stirring in step 2 refers to continuous stirring at 2000-2500 r / min until the two are evenly mixed to obtain an emulsion mixture.

4. The method for preparing a PVC flame retardant and smoke suppressant according to claim 1, characterized in that: The particle size of the nano magnesium hydroxide is 50-100 nm, and the particle size of the nano silicon dioxide is 50-100 nm.

5. The method for preparing a PVC flame retardant and smoke suppressant according to claim 1, characterized in that: The screening in step 3 refers to screening out PVC flame retardant and smoke suppressant particles with a particle size of 300-1000 nm.

6. A PVC flame retardant smoke suppressant, characterized in that: The PVC flame retardant and smoke suppressant is prepared by the preparation method of the PVC flame retardant and smoke suppressant according to any one of claims 1 to 5.

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