Low-smoke low-halogen polyvinyl chloride cable material and preparation method thereof

Abstract

This application relates to the field of cable materials, specifically disclosing a low-smoke, low-halogen polyvinyl chloride (PVC) cable material and its preparation method. The material includes the following raw materials: polyvinyl chloride resin, EVM500 rubber, heat stabilizer, antioxidant, plasticizer, lubricant, filler, flame retardant, flame retardant synergist, and acrylate processing aids. The flame retardant includes a mixture of aluminum hydroxide and magnesium hydroxide, and the flame retardant synergist includes a zinc borate and ammonium octamolate-sepiolite composite. The preparation method includes the following steps: mixing the raw materials according to a specified ratio, then melting and mixing them, followed by granulation and extrusion molding to obtain the low-smoke, low-halogen PVC cable material. This application alleviates the problem of traditional PVC cable materials producing large amounts of black smoke and toxic gases during combustion, reduces smoke density, and improves the material's environmental performance and flame retardant properties.

Description

Technical Field

[0001] This application relates to the field of cable materials, and more specifically, to a low-smoke, low-halogen polyvinyl chloride cable material and its preparation method. Background Technology

[0002] With increasingly stringent global requirements for fire safety and environmental protection, traditional PVC cable materials, which produce large amounts of black smoke and harmful gases during combustion, are unable to meet the current demand for low-smoke, low-halogen, or even halogen-free environmentally friendly materials. Therefore, developing a low-smoke, low-halogen PVC cable material with good flame-retardant properties that significantly reduces smoke and toxic gas release has become a pressing problem for the industry.

[0003] Currently, to improve the flame retardant properties of polyvinyl chloride (PVC) cable materials, flame retardant synergists such as antimony trioxide are usually added and used in combination with halogenated flame retardants to enhance the flame retardant effect. However, these synergists produce a large amount of black smoke and toxic gases during combustion, posing a threat to the environment and human health. Therefore, it is of great significance to provide new PVC cable materials that can effectively alleviate the problem of producing a large amount of black smoke and toxic gases during combustion of traditional PVC cable materials and improve the environmental protection and flame retardant properties of the materials. Summary of the Invention

[0004] To alleviate the problem of traditional PVC cable materials producing large amounts of black smoke and toxic gases during combustion, reduce smoke density, and improve the environmental performance and flame retardant properties of the material, this application provides a low-smoke, low-halogen PVC cable material and its preparation method.

[0005] Firstly, this application provides a low-smoke, low-halogen polyvinyl chloride cable material, employing the following technical solution: A low-smoke, low-halogen polyvinyl chloride cable material comprises the following raw materials in parts by weight: The composition includes 60-80 parts polyvinyl chloride resin, 20-40 parts EVM500 rubber, 6-10 parts heat stabilizer, 0.1-0.5 parts antioxidant, 30-50 parts plasticizer, 0.5-1 part lubricant, 15-25 parts filler, 20-30 parts flame retardant, 8-15 parts flame retardant synergist, and 0.5-1 part acrylate processing aid. The flame retardant includes a mixture of aluminum hydroxide and magnesium hydroxide, and the flame retardant synergist includes zinc borate and ammonium octamolate-sepiolite complex. The ammonium octamolate-sepiolite composite was prepared by pretreating sepiolite by acid leaching and grafting with a vinylsilane coupling agent. Then, the pretreated sepiolite was dispersed in an aqueous solution of ammonium molybdate and dilute nitric acid was added dropwise to precipitate ammonium octamolate in situ on the surface of the pretreated sepiolite, thus obtaining a primary modified composite. The primary modified composite was then polymerized with acrylate monomers under the action of an initiator to obtain the ammonium octamolate-sepiolite composite.

[0006] By adopting the above technical solution, polyvinyl chloride resin is used as the base material of cable material in this application, providing basic mechanical and processing properties. However, its chlorine content causes a large amount of black smoke and toxic gases to be produced during combustion. To address this, this application adds EVM500 rubber, which produces white smoke when burned compared to polyvinyl chloride, thus reducing the chlorine content. This rubber partially replaces PVC in cable manufacturing, resulting in a reduction in the chlorine content of the final cable material product. This not only improves environmental performance but also alleviates the black smoke phenomenon caused by chlorine during combustion and reduces the release of toxic substances at high temperatures. On the other hand, this application adds aluminum hydroxide and magnesium hydroxide as flame retardants. Based on this, zinc borate and ammonium octamolate-sepiolite composite are used as flame retardant synergists. Zinc borate promotes char formation and reduces the rate of heat release during combustion, thus improving flame retardant performance in combination with flame retardants. Ammonium octamolate, during combustion, catalyzes the formation of a char layer through molybdenum compounds, covering the material surface and isolating oxygen and heat transfer to play a flame retardant role. More importantly, during the combustion of polyvinyl chloride, molybdenum compounds catalyze the formation of trans-polyene structures, reducing the formation of aromatic compounds (the main components of smoke). Finally, ammonium octamolate significantly reduces smoke density by inhibiting the formation of smoke precursors and reducing the release of combustible gases. Combined with zinc borate to promote char formation and prevent the overflow of volatile combustible gases, it synergistically suppresses smoke with molybdenum compounds, ultimately producing cable materials with low smoke and low halogen content, which are more environmentally friendly.

[0007] In this application, ammonium octamolybdate is loaded onto sepiolite and then copolymerized in situ with methacrylate monomers to form acrylate polymers on its surface. Sepiolite acts as a carrier to fix ammonium octamolybdate and promote its uniform dispersion. At the same time, it can adsorb acidic gases generated during combustion, reducing the production of dense black smoke. Finally, the surface monomers polymerize to introduce ester groups on the surface of the composite, which reduces agglomeration. More importantly, it forms polyacrylate with excellent compatibility with polyvinyl chloride without introducing chlorine, forming a uniform mixed system. Moreover, the polymer chains formed are entangled with PVC molecular chains to form an interpenetrating network structure, which significantly improves the interfacial bonding force, enhances the bonding between the composite and the polyvinyl chloride, improves the dispersibility and stability in the cable material, and distributes more uniformly in the PVC cable material, thereby more effectively releasing its flame retardant and smoke-suppressing effects.

[0008] Optionally, the ammonium octamolate-sepiolite composite is prepared by the following method: 1) Disperse sepiolite in 1-3 mol / L dilute hydrochloric acid, stir at 60-80℃ for 2-3 h, filter, wash with water and dry to obtain activated sepiolite; 2) Disperse activated sepiolite in an aqueous ethanol solution, add vinyltrimethoxysilane, reflux at 70-80℃ for 4-6 hours, filter, and obtain pretreated sepiolite; 3) Disperse the pretreated sepiolite in an aqueous solution of ammonium molybdate, ultrasonically disperse for 20-30 min, add dilute nitric acid to adjust the pH to 3-4, stir for 10-20 min, let stand, filter, wash and dry to obtain the initial modified complex. 4) Dissolve sodium dodecyl sulfate and polyoxyethylene ether in water, add acrylate monomers, stir for 30-40 minutes to form a monomer emulsion, then add the initial modified complex to 1 / 3-1 / 2 of the monomer emulsion, and disperse by ultrasonication to obtain the initial mixed reaction solution. Then, the remaining monomer emulsion is mixed with 1 / 3 to 1 / 2 of potassium persulfate solution, heated to 70-80℃, and stirred for 30-40 minutes to form a seed emulsion. The initial mixed reaction solution and the remaining potassium persulfate solution were added dropwise to the seed emulsion. The temperature was maintained at 70-80℃, and the reaction was carried out for 2-3 hours. After the reaction was completed, the mixture was cooled to room temperature, calcium chloride solution was added, and the mixture was filtered, washed with water, and dried to obtain the ammonium octamolybdate-sepiolite complex.

[0009] By adopting the above technical solution, this application first treats sepiolite with dilute hydrochloric acid to remove impurities and increase its specific surface area. The hydroxyl groups formed on the surface of sepiolite provide reaction sites for subsequent silane coupling agents. Then, it reacts with vinyltrimethoxysilane to introduce vinyl groups onto the surface of sepiolite. After dispersing it in an ammonium molybdate aqueous solution, dilute nitric acid is added dropwise to allow ammonium octamolybdate to precipitate in situ on the surface of sepiolite. The porous structure of the sepiolite surface, through physical action and coordination with surface hydroxyl groups, fixes the ammonium octamolybdate. Finally, under the action of ammonium persulfate, acrylate monomers polymerize with the vinyl functional groups on the surface of sepiolite to form polyacrylate on the surface of the composite, improving the compatibility of the composite with polyvinyl chloride. Moreover, the formed acrylate coating decomposes to generate gases such as carbon dioxide during combustion, diluting the concentration of oxygen and combustible gases and inhibiting the combustion chain reaction.

[0010] Optionally, in the preparation of the ammonium octamolate-sepiolite composite, in step 1), the mass concentration of sepiolite to dilute hydrochloric acid is 1:(4-6). In step 2), the amount of vinyltrimethoxysilane added is 5-8 wt% of the activated sepiolite, and the ethanol aqueous solution is prepared by mixing ethanol and water in a volume ratio of (7-9):(1-3), and the amount of ethanol aqueous solution added is 6-7 times the mass of the activated sepiolite. In step 3), the mass concentration of ammonium molybdate in the aqueous solution of ammonium molybdate is 3-4 wt%, and the mass ratio of ammonium molybdate to sepiolite is 1:(2-3). In step 4), the amount of ammonium dodecyl sulfate added is 2-5 wt% of the acrylate monomers, the amount of polyoxyethylene ether added is 1-2 wt% of the acrylate monomers, and the mass ratio of the acrylate monomers to the primary modified compound is (0.5-0.8):1. The amount of water added is 8-10 times the mass of the primary modified compound. The amount of potassium persulfate added is 0.5-1 wt% of the acrylate monomers, and the mass concentration of the potassium persulfate solution is 5-10 wt%. The mass concentration of the calcium chloride solution is 5-10 wt%, and the amount of calcium chloride added is 1-3 wt% of the acrylate monomers.

[0011] Optionally, in the preparation of the ammonium octamolate-sepiolite composite, the acrylate monomers in step 3) are prepared by mixing methyl methacrylate and butyl acrylate in a mass ratio of (2-3):1.

[0012] Optionally, in the preparation of the ammonium octamolate-sepiolite composite, in step 1), the activated sepiolite is first added to a 20-30 wt% aqueous solution of mercaptoacetic acid, the amount of mercaptoacetic acid added is 3-5 wt% of the activated sepiolite, stirred at 70-80℃ for 2-4 h, filtered, washed with water, and dried to obtain mercapto-modified sepiolite, and then the mercapto-modified sepiolite is subjected to step 2).

[0013] By adopting the above technical solution, after the activated sepiolite was first modified with mercaptoacetic acid, it was found that the final flame retardant and smoke suppressant performance was better. On the one hand, the introduction of mercapto groups may help improve the adsorption performance of gases such as hydrogen chloride and particulate matter generated during the combustion of PVC cable materials. Moreover, the mercapto groups can react with hydrogen chloride to reduce the subsequent generation and carbonization of unsaturated hydrocarbons, thereby reducing the amount of black smoke. On the other hand, the polar groups contained on the surface of mercapto-modified sepiolite interact with the PVC molecular chains to form a stronger interfacial bond, which helps to improve the dispersion uniformity and compatibility, thus playing a better role. In addition, the mercapto groups in mercaptoacetic acid react with magnesium ions or silanol groups in sepiolite to introduce mercapto functional groups. These groups can further react with molybdate ions in ammonium octamolate to form stable chemical bonds, enhancing the binding force between ammonium octamolate and sepiolite, reducing the shedding of ammonium octamolate during subsequent polymerization, and maintaining its quantity to play a role in flame retardant and smoke suppressant.

[0014] Optionally, in the preparation of the ammonium octamolate-sepiolite composite, in step 3), the aqueous solution of ammonium molybdate is first mixed with a treatment solution containing diethylenetriamine, PAMAM and maleic anhydride, and then pretreated sepiolite is added for ultrasonic dispersion. The treatment solution is prepared by mixing diethylenetriamine, PAMAM, maleic anhydride and water in a mass ratio of 1:(0.1-0.2):(0.1-0.2):(3-4), and the amount of treatment solution added is 0.3-0.4 times the mass of the pretreated sepiolite.

[0015] By adopting the above technical solution, the ammonium molybdate aqueous solution is first mixed with the treatment solution. The addition of maleic anhydride in the treatment solution can introduce unsaturated double bonds in sepiolite, further providing active sites for the subsequent polymerization of acrylate monomers. The amino groups in the treatment solution can first form coordination with molybdate ions, and then the pretreated sepiolite is added, so that the molybdate ions precipitate on the surface of the sepiolite. The polyamino functional groups in diethylenetriamine and PAMAM can form chemical bonds with magnesium ions or silanol groups on the surface of sepiolite, and can also form chemical bonds with molybdate ions in octamolybdate, which helps to stabilize the loading of octamolybdate on the sepiolite. Moreover, the timing of the addition of the treatment solution in this application allows the amino groups to form coordination with the molybdate ions, which slows down the precipitation rate and makes the octamolybdate more uniformly loaded on the surface of the sepiolite.

[0016] Optionally, calcium-zinc stabilizer can be used as the heat stabilizer, and antioxidant 1010 can be used as the antioxidant. The lubricant used is stearic acid and oxidized polyethylene wax in a mass ratio of 1:(0.8-1.2).

[0017] By adopting the above technical solution, stearic acid is used as a lubricant to improve the processing performance of cable material, and oxidized polyethylene wax is used as an external lubricant to further improve the processing performance of cable material, improve surface smoothness, and facilitate processing and molding.

[0018] Optionally, the filler material can be kaolin and montmorillonite in a mass ratio of 1:(0.8-1.2); The plasticizer is a mixture of triisooctyl acetyl citrate, trioctyl trimellitate and dioctyl sebacate in a mass ratio of 1:(0.6-0.8):(0.2-0.3).

[0019] By adopting the above technical solution, this application selects citrate ester plasticizers to replace traditional phthalate plasticizers, which reduces the release of toxic substances and not only improves flexibility, but also has better heat resistance and environmental friendliness.

[0020] Optionally, the flame retardant includes a mixture of aluminum hydroxide and magnesium hydroxide in a mass ratio of 1:(1.8-2); The flame retardant synergist consists of a mixture of zinc borate and ammonium octamolate-sepiolite complex in a mass ratio of 1:(2-3).

[0021] Secondly, this application provides a method for preparing low-smoke, low-halogen polyvinyl chloride cable material, employing the following technical solution: A method for preparing low-smoke, low-halogen polyvinyl chloride cable material includes the following steps: The raw materials are mixed according to the specified ratio, melted and mixed, then granulated and extruded to obtain low-smoke, low-halogen polyvinyl chloride cable material.

[0022] By adopting the above technical solution, the method provided in this application is simple, convenient, and easy to industrialize.

[0023] In summary, this application has the following beneficial effects: 1. In this application, EVM500 rubber is added. Compared with polyvinyl chloride, it produces white smoke when burned, thus reducing the chlorine content. It can partially replace PVC in cable manufacturing, thereby reducing the chlorine content in the final cable material product. This not only improves environmental performance but also alleviates the black smoke phenomenon caused by chlorine combustion and reduces the release of toxic substances at high temperatures. 2. This application adds aluminum hydroxide and magnesium hydroxide as flame retardants. On this basis, zinc borate and ammonium octamolate-sepiolite complex are used as flame retardant synergists. Ammonium octamolate significantly reduces smoke density by inhibiting the formation of smoke precursors and reducing the release of combustible gases. In combination with zinc borate, it promotes char formation and prevents the overflow of volatile combustible gases. It also works synergistically with molybdenum compounds to suppress smoke, ultimately producing cable material with low smoke and low halogen content, which is more environmentally friendly and reduces smoke density. 3. In this application, ammonium octamolybdate is loaded onto sepiolite and then copolymerized in situ with methacrylate monomers to form acrylate polymers on its surface. Sepiolite acts as a carrier to fix ammonium octamolybdate and promote its uniform dispersion. At the same time, it can adsorb acidic gases generated during combustion, reducing the production of dense black smoke. Finally, the surface monomers polymerize to introduce ester groups on the surface of the composite, which reduces agglomeration. More importantly, it forms polyacrylate with excellent compatibility with polyvinyl chloride without introducing chlorine, forming a uniform mixed system. Moreover, the polymer chains formed are entangled with PVC molecular chains to form an interpenetrating network structure, which significantly improves the interfacial bonding force, enhances the bonding between the composite and polyvinyl chloride, improves the dispersibility and stability in the cable material, and distributes more uniformly in the PVC cable material, thereby more effectively volatilizing its flame retardant and smoke-suppressing effects and reducing smoke density. Detailed Implementation

[0024] The following detailed description of this application is provided in conjunction with the embodiments. It should be noted that: unless otherwise specified, the conditions in the following embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following embodiments are all from commercially available sources.

[0025] In the following examples, the polyvinyl chloride resin used is a polyvinyl chloride resin with a degree of polymerization of 1300, CAS number 9002-86-2; The specific acrylic processing aid selected is model P-551J, which is Mitsubishi P-5551J methacrylic PVC processing aid from Japan. The oxidized polyethylene wax used is Honeywell AC-629A. EVM500 rubber is made from ethylene-vinyl acetate copolymer of Hubei Guangcheng New Material Co., Ltd., branded as Alangxinke and graded as EVM500.

[0026] The following preparation examples illustrate the preparation of ammonium octamolate-sepiolite composites. Preparation Example 1 A method for preparing an ammonium octamolate-sepiolite composite includes the following steps: 1) Sepiolite was dispersed in 2 mol / L dilute hydrochloric acid at a mass ratio of 1:5. After stirring at 70℃ for 2.5 h, the mixture was filtered, washed with water, and dried to obtain activated sepiolite. 2) Ethanol and water were mixed at a volume ratio of 8:2 to prepare an ethanol aqueous solution. Then, activated sepiolite was dispersed in an ethanol aqueous solution at a mass ratio of 6. Vinyltrimethoxysilane KH-171 was added, with the amount of vinyltrimethoxysilane added being 6 wt% of the activated sepiolite. The mixture was refluxed at 75°C for 5 h and then filtered to obtain pretreated sepiolite. 3) Dissolve ammonium molybdate powder in water to obtain an ammonium molybdate solution with a mass concentration of 3.5 wt%, and the mass ratio of ammonium molybdate to sepiolite is 1:2.5. Then, disperse the pretreated sepiolite in the ammonium molybdate aqueous solution, ultrasonically disperse for 25 min, add dilute nitric acid to adjust the pH to 3.5, stir for 15 min, let stand, filter, wash and dry to obtain the initial modified composite. 4) Dissolve sodium dodecyl sulfate and polyoxyethylene ether OP-10 in water, add acrylate monomers, stir for 35 minutes to form a monomer emulsion, then add the initial modified complex to 1 / 3 of the monomer emulsion, and disperse by ultrasonication to obtain the initial mixed reaction solution. Then the remaining monomer emulsion was mixed with 1 / 3 of the potassium persulfate solution, heated to 75°C, and stirred for 35 minutes to form a seed emulsion. The initial mixed reaction solution and the remaining potassium persulfate solution were added dropwise to the seed emulsion. The temperature was maintained at 75℃ and the reaction was carried out for 2.5 hours. After the reaction was completed, the mixture was cooled to room temperature, calcium chloride solution was added, and the mixture was filtered, washed with water, and dried to obtain the ammonium octamolybdate-sepiolite complex.

[0027] In step 4), the acrylate monomers are a mixture of methyl methacrylate and butyl acrylate in a mass ratio of 2.5:1. The amount of ammonium dodecyl sulfate added is 3 wt% of the acrylate monomers, the amount of polyoxyethylene ether OP-10 added is 1.5 wt% of the acrylate monomers, and the mass ratio of the acrylate monomers to the initial modified compound is 0.6:1. The amount of water added is 9 times the mass of the initial modified compound. The total amount of potassium persulfate added is 0.8 wt% of the acrylate monomers, and the mass concentration of the potassium persulfate solution is 8 wt%. The mass concentration of the calcium chloride solution is 8 wt%, and the amount of calcium chloride added is 2 wt% of the acrylate monomers.

[0028] Preparation Example 2 A method for preparing an ammonium octamolate-sepiolite composite includes the following steps: 1) Sepiolite was dispersed in 1 mol / L dilute hydrochloric acid at a mass ratio of 1:4. After stirring at 60℃ for 3 hours, the mixture was filtered, washed with water, and dried to obtain activated sepiolite. 2) Ethanol and water were mixed at a volume ratio of 7:3 to prepare an ethanol aqueous solution. Then, activated sepiolite was dispersed in an ethanol aqueous solution at a mass ratio of 6. Vinyltrimethoxysilane KH-171 was added, with the amount of vinyltrimethoxysilane added being 5 wt% of the activated sepiolite. The mixture was refluxed at 70°C for 6 hours and then filtered to obtain pretreated sepiolite. 3) Dissolve ammonium molybdate powder in water to obtain an ammonium molybdate solution with a mass concentration of 3wt%, and the mass ratio of ammonium molybdate to sepiolite is 1:2. Then, disperse the pretreated sepiolite in the ammonium molybdate aqueous solution, ultrasonically disperse for 20 min, add dilute nitric acid to adjust the pH to 3, stir for 10 min, let stand, filter, wash and dry to obtain the initial modified composite. 4) Dissolve sodium dodecyl sulfate and polyoxyethylene ether OP-10 in water, add acrylate monomers, stir for 30 minutes to form a monomer emulsion, then add the initial modified complex to 1 / 3 of the monomer emulsion, and disperse by ultrasonication to obtain the initial mixed reaction solution. Then the remaining monomer emulsion was mixed with 1 / 3 of the potassium persulfate solution, heated to 70°C, and stirred for 40 minutes to form a seed emulsion. The initial mixed reaction solution and the remaining potassium persulfate solution were added dropwise to the seed emulsion. The temperature was maintained at 70℃ and the reaction was carried out for 3 hours. After the reaction was completed, the mixture was cooled to room temperature, calcium chloride solution was added, and the mixture was filtered, washed with water, and dried to obtain the ammonium octamolybdate-sepiolite complex.

[0029] In step 4), the acrylate monomers are a mixture of methyl methacrylate and butyl acrylate in a mass ratio of 2:1. The amount of ammonium dodecyl sulfate added is 2 wt% of the acrylate monomers, the amount of polyoxyethylene ether OP-10 added is 1 wt% of the acrylate monomers, and the mass ratio of the acrylate monomers to the initial modified compound is 0.5:1. The amount of water added is 8 times the mass of the initial modified compound. The amount of potassium persulfate added is 0.5 wt% of the acrylate monomers, and the mass concentration of the potassium persulfate solution is 5 wt%. The mass concentration of the calcium chloride solution is 5 wt%, and the amount of calcium chloride added is 1 wt% of the acrylate monomers.

[0030] Preparation Example 3 A method for preparing an ammonium octamolate-sepiolite composite includes the following steps: 1) Sepiolite was dispersed in 3 mol / L dilute hydrochloric acid at a mass ratio of 1:6. After stirring at 80℃ for 2 hours, the mixture was filtered, washed with water, and dried to obtain activated sepiolite. 2) Ethanol and water were mixed at a volume ratio of 9:1 to prepare an ethanol aqueous solution. Then, activated sepiolite was dispersed in an ethanol aqueous solution at a mass ratio of 7. Vinyltrimethoxysilane KH-171 was added, with the amount of vinyltrimethoxysilane added being 8 wt% of the activated sepiolite. After reflux reaction at 80°C for 6 h, the mixture was filtered to obtain pretreated sepiolite. 3) Dissolve ammonium molybdate powder in water to obtain an ammonium molybdate solution with a mass concentration of 4 wt%, and the mass ratio of ammonium molybdate to sepiolite is 1:2. Then, disperse the pretreated sepiolite in the ammonium molybdate aqueous solution, ultrasonically disperse for 30 min, add dilute nitric acid to adjust the pH to 4, stir for 20 min, let stand, filter, wash and dry to obtain the initial modified composite. 4) Dissolve sodium dodecyl sulfate and polyoxyethylene ether OP-10 in water, add acrylate monomers, stir for 40 min to form a monomer emulsion, then add the initial modified complex to 1 / 2 of the monomer emulsion, and disperse by ultrasonication to obtain the initial mixed reaction solution. Then the remaining monomer emulsion was mixed with 1 / 2 potassium persulfate solution, heated to 80°C, and stirred for 30 minutes to form a seed emulsion. The initial mixed reaction solution and the remaining potassium persulfate solution were added dropwise to the seed emulsion. The temperature was maintained at 80℃ and the reaction was carried out for 2 hours. After the reaction was completed, the mixture was cooled to room temperature, calcium chloride solution was added, and the mixture was filtered, washed with water, and dried to obtain the ammonium octamolybdate-sepiolite complex.

[0031] In step 4), the acrylate monomers are a mixture of methyl methacrylate and butyl acrylate in a mass ratio of 3:1. The amount of ammonium dodecyl sulfate added is 5 wt% of the acrylate monomers, the amount of polyoxyethylene ether OP-10 added is 2 wt% of the acrylate monomers, and the mass ratio of the acrylate monomers to the initial modified compound is 0.8:1. The amount of water added is 10 times the mass of the initial modified compound. The amount of potassium persulfate added is 1 wt% of the acrylate monomers, and the mass concentration of the potassium persulfate solution is 10 wt%. The mass concentration of the calcium chloride solution is 10 wt%, and the amount of calcium chloride added is 3 wt% of the acrylate monomers.

[0032] Preparation Example 4 A method for preparing an ammonium octamolate-sepiolite composite is carried out according to the method in Preparation Example 1, except that in step 1), the obtained activated sepiolite is first added to a 25 wt% aqueous solution of mercaptoacetic acid (prepared by mixing mercaptoacetic acid and water), the amount of mercaptoacetic acid added is 4 wt% of the activated sepiolite, stirred at 75°C for 3 h, filtered, washed with water, and dried to obtain mercapto-modified sepiolite, and then the mercapto-modified sepiolite is subjected to step 2).

[0033] Preparation Example 5 A method for preparing an ammonium octamolate-sepiolite composite is carried out according to the method in Preparation Example 1, except that in step 1), the obtained activated sepiolite is first added to a 20wt% aqueous solution of mercaptoacetic acid (prepared by mixing mercaptoacetic acid and water), the amount of mercaptoacetic acid added is 3wt% of the activated sepiolite, stirred at 70℃ for 4h, filtered, washed with water, and dried to obtain mercapto-modified sepiolite, and then the mercapto-modified sepiolite is subjected to step 2).

[0034] Preparation Example 6 A method for preparing an ammonium octamolate-sepiolite composite is carried out according to the method in Preparation Example 1, except that in step 1), the obtained activated sepiolite is first added to a 30wt% aqueous solution of mercaptoacetic acid (prepared by mixing mercaptoacetic acid and water), the amount of mercaptoacetic acid added is 5wt% of the activated sepiolite, stirred at 80℃ for 4h, filtered, washed with water, and dried to obtain mercapto-modified sepiolite, and then the mercapto-modified sepiolite is subjected to step 2).

[0035] Preparation Example 7 A method for preparing an ammonium octamolate-sepiolite composite is carried out according to the method in Preparation Example 1, except that in step 3), the aqueous solution of ammonium molybdate is first mixed with a treatment solution containing diethylenetriamine, PAMAM and maleic anhydride, and then pretreated sepiolite is added and ultrasonically dispersed. The treatment solution is prepared by mixing diethylenetriamine, PAMAM, maleic anhydride and water in a mass ratio of 1:0.1:0.1:3, and the amount of treatment solution added is 0.3 times the mass of pretreated sepiolite.

[0036] Preparation Example 8 A method for preparing an ammonium octamolate-sepiolite composite is carried out according to the method in Preparation Example 1, except that in step 3), the aqueous solution of ammonium molybdate is first mixed with a treatment solution containing diethylenetriamine, PAMAM and maleic anhydride, and then pretreated sepiolite is added and ultrasonically dispersed. The treatment solution is prepared by mixing diethylenetriamine, PAMAM, maleic anhydride and water in a mass ratio of 1:0.2:0.2:4, and the amount of treatment solution added is 0.4 times the mass of pretreated sepiolite.

[0037] Preparation Example 9 A method for preparing an ammonium octamolate-sepiolite complex is carried out according to the method in Preparation Example 7, except that maleic anhydride is not added to the treatment solution.

[0038] Preparation Example 10 A method for preparing an ammonium octamolate-sepiolite complex is carried out according to the method in Preparation Example 7, except that diethylenetriamine in the treatment solution is replaced with an equal amount of PAMAM.

[0039] Preparation Example 11 A method for preparing an ammonium octamolate-sepiolite complex is carried out according to the method in Preparation Example 7, except that PAMAM in the treatment solution is replaced with an equal amount of diethylenetriamine.

[0040] Comparative Preparation Example 1 A method for preparing an ammonium octamolate-sepiolite composite is carried out according to the method in Preparation Example 1, except that steps 2) and 4) are not performed, and step 3) is performed directly after step 1) to obtain the initial modified composite for use as an ammonium octamolate-sepiolite composite.

[0041] Example 1

[0042] A method for preparing low-smoke, low-halogen polyvinyl chloride cable material includes the following steps: S1. Add 70kg of polyvinyl chloride resin, 30kg of EVM500 rubber, 8kg of heat stabilizer, 0.3kg of antioxidant, 40kg of plasticizer, 0.8kg of lubricant, 20kg of filler, 25kg of flame retardant, 12kg of flame retardant synergist, and 0.8kg of acrylate processing aid to a high-speed mixer and mix at 700rpm for 8min to obtain a mixture. S2. Add the mixture to a twin-screw extruder at a screw speed of 180 rpm. After melt-blending at 170°C for 8 minutes, extrude the strip material, water-cool and pelletize it, and dry it to obtain dried granules. S3. Add the dried granules into a single-screw extruder and extrude them into cable material at 180°C with a screw speed of 120 rpm.

[0043] In step S1, the heat stabilizer is selected from calcium-zinc stabilizer, the antioxidant is selected from antioxidant 1010, and the lubricant is selected from a mixture of stearic acid and oxidized polyethylene wax in a mass ratio of 1:1. The plasticizer is a mixture of triisooctyl acetyl citrate, trioctyl trimellitate, and dioctyl sebacate in a mass ratio of 1:0.7:0.3; The filler material is a mixture of kaolin and montmorillonite in a mass ratio of 1:1; The flame retardant is a mixture of aluminum hydroxide and magnesium hydroxide in a mass ratio of 1:1.9. The flame retardant synergist comprises a mixture of zinc borate in a mass ratio of 1:2.5 and the ammonium octamolate-sepiolite complex prepared in Preparation Example 1.

[0044] Example 2

[0045] A method for preparing low-smoke, low-halogen polyvinyl chloride cable material includes the following steps: S1. Add 60kg of polyvinyl chloride resin, 20kg of EVM500 rubber, 6kg of heat stabilizer, 0.1kg of antioxidant, 30kg of plasticizer, 0.5kg of lubricant, 15kg of filler, 20kg of flame retardant, 8kg of flame retardant synergist, and 0.5kg of acrylate processing aid to a high-speed mixer and mix at 500rpm for 5min to obtain a mixture. S2. Add the mixture to a twin-screw extruder at a screw speed of 150 rpm. After melting and blending at 160°C for 10 minutes, extrude the strip material, water-cool and pelletize it, and dry it to obtain dried granules. S3. Add the dried granules into a single-screw extruder and extrude them into cable material at 170°C with a screw speed of 100 rpm.

[0046] In step S1, the heat stabilizer is selected from calcium-zinc stabilizer, the antioxidant is selected from antioxidant 1010, and the lubricant is selected from a mixture of stearic acid and oxidized polyethylene wax with a mass ratio of 1:0.8. The plasticizer is a mixture of triisooctyl acetyl citrate, trioctyl trimellitate, and dioctyl sebacate in a mass ratio of 1:0.6:0.2; The filler material is a mixture of kaolin and montmorillonite with a mass ratio of 1:0.8; The flame retardant is a mixture of aluminum hydroxide and magnesium hydroxide in a mass ratio of 1:1.8. The flame retardant synergist comprises a mixture of zinc borate in a mass ratio of 1:2 and the ammonium octamolate-sepiolite complex prepared in Preparation Example 2.

[0047] Example 3

[0048] A method for preparing low-smoke, low-halogen polyvinyl chloride cable material includes the following steps: S1. Add 80kg of polyvinyl chloride resin, 40kg of EVM500 rubber, 10kg of heat stabilizer, 0.5kg of antioxidant, 50kg of plasticizer, 1kg of lubricant, 25kg of filler, 30kg of flame retardant, 15kg of flame retardant synergist, and 1kg of acrylate processing aid to a high-speed mixer and mix at 800rpm for 10min to obtain a mixture. S2. Add the mixture to a twin-screw extruder at a screw speed of 200 rpm. After melting and blending at 180°C for 5 minutes, extrude the strip material, water-cool and pelletize it, and dry it to obtain dried granules. S3. Add the dried granules into a single-screw extruder and extrude them into cable material at 190°C with a screw speed of 150 rpm.

[0049] In step S1, the heat stabilizer is selected from calcium-zinc stabilizer, the antioxidant is selected from antioxidant 1010, and the lubricant is selected from a mixture of stearic acid and oxidized polyethylene wax with a mass ratio of 1:1.2. The plasticizer is a mixture of triisooctyl acetyl citrate, trioctyl trimellitate, and dioctyl sebacate in a mass ratio of 1:0.8:0.3; The filler material is a mixture of kaolin and montmorillonite with a mass ratio of 1:1.2; The flame retardant is a mixture of aluminum hydroxide and magnesium hydroxide in a mass ratio of 1:2. The flame retardant synergist comprises a mixture of zinc borate in a mass ratio of 1:3 and the ammonium octamolate-sepiolite composite prepared in Preparation Example 3.

[0050] Example 4-11 A method for preparing a low-smoke, low-halogen polyvinyl chloride cable material is carried out according to the method in Example 1, except that the ammonium octamolate-sepiolite composite in step S1 is selected from the ammonium octamolate-sepiolite composites prepared in Examples 4-11.

[0051] Comparative Example 1 A method for preparing a low-smoke, low-halogen polyvinyl chloride cable material is carried out according to the method in Example 1, except that the ammonium octamolate-sepiolite composite in step S1 is the ammonium octamolate-sepiolite composite obtained in Comparative Preparation Example 1.

[0052] Comparative Example 2 A method for preparing a low-smoke, low-halogen polyvinyl chloride cable material is carried out according to the method in Example 1, except that in step S1, the ammonium octamolate-sepiolite composite is replaced by an equal amount of ammonium octamolate.

[0053] Comparative Example 3 A method for preparing a low-smoke, low-halogen polyvinyl chloride cable material is carried out according to the method in Example 1, except that in step S1, the ammonium octamolate-sepiolite composite is replaced by an equal amount of a mixture of ammonium octamolate and sepiolite, and the mass ratio of ammonium octamolate to sepiolite is 1:2.5.

[0054] Comparative Example 4 A method for preparing a low-smoke, low-halogen polyvinyl chloride cable material is carried out according to the method in Example 1, except that zinc borate is used as the flame retardant synergist in step S1.

[0055] Performance testing The low-smoke, low-halogen PVC cable materials prepared in the above examples and comparative examples were tested for oxygen index according to GB / T 2406.2-2009 to characterize their flame retardant properties. In addition, the peak smoke production rate (SPR peak), total smoke production after 1200s of fire exposure (TSP1200), and minimum light transmittance It (%) were tested according to GB / T 17651.2-1998 to characterize smoke density. The test results are shown in Table 1 below.

[0056] Table 1:

[0057] The higher the oxygen index, the better the flame retardant performance. The peak SPR reflects the maximum rate of smoke release in the early stage of combustion. The lower the value, the more effectively the rapid smoke generation can be suppressed in the early stage of a fire. TSP1200 reflects the total amount of smoke released by the cable during 1200s of continuous combustion. The lower the value, the less smoke the material produces in the cycle, and the better the overall smoke suppression performance. The It value reflects the ability of smoke to block light. The higher the value, the better the light transmittance of the surface smoke and the higher the visibility at the fire scene.

[0058] Based on the test results in Table 1, the SPR peak value of the cable material prepared in this embodiment is ≤0.3m. 2 / s, TSP1200≤75m 2 With an octylmolybdate content ≥ 80%, the smoke density is lower. In this application, smoke suppression is achieved through the synergistic effect of flame retardants (aluminum hydroxide / magnesium hydroxide), flame retardant synergists (ammonium octamolybdate-sepiolite composite / zinc borate), and low-chlorine matrix (EVM500 rubber). This is achieved from three dimensions: inhibiting the formation of smoke precursors, promoting char formation to isolate oxygen, and adsorbing acidic gases and particulate matter. Moreover, the polyacrylate coating layer on the surface of the ammonium octamolybdate-sepiolite composite decomposes to generate gases such as carbon dioxide during combustion, diluting the concentration of oxygen and combustible gases and inhibiting the combustion chain reaction. At the same time, the porous structure of sepiolite adsorbs acidic gases and particulate matter generated during combustion, reducing the formation of dense black smoke.

[0059] Combining the test results of Examples 1 and 4-6, in Examples 4-6, when the ammonium octamolybdate-sepiolite composite was prepared, the activated sepiolite after acid leaching was also modified with mercaptoacetic acid, which further reduced the SPR peak and TSP1200, increased It, and further reduced the smoke density. Combining the test results of Examples 7 and 8, in Examples 7 and 8, when ammonium octamolybdate was precipitated in situ, when a treatment was added to the ammonium molybdate solution, its flame retardant performance was improved and the smoke density was further reduced. The introduction of amino groups in the treatment solution further enhanced the binding between ammonium octamolybdate and sepiolite, reduced the shedding of ammonium octamolybdate, and exerted better flame retardant and smoke suppression performance. Combining the test results of Examples 7 and 9, when maleic anhydride was not added to the treatment solution, its flame retardant and smoke suppressing effect was reduced. The addition of maleic anhydride helps to introduce unsaturated bonds in sepiolite, which helps to form subsequent acrylate polymers, reduces the aggregation of the complex, and improves the uniform dispersion of the complex in polyvinyl chloride, thereby improving its flame retardant and smoke suppressing performance. Combining the test results of Examples 10 and 11, when only diethylenetriamine or PAMAM was added to the treatment solution, compared with the simultaneous addition in Example 7, the binding force between the single amine and sepiolite was weakened, and its flame retardant and smoke suppressing performance was reduced.

[0060] Combining the test results of Example 1 and Comparative Example 1, in Comparative Example 1, ammonium octamolate was directly loaded onto sepiolite as a composite addition. When the acrylate polymer was not formed, its compatibility with polyvinyl chloride may be poor, and it is easy to agglomerate, which reduces its flame retardant and smoke suppressing effect. In Comparative Example 2, when ammonium octamolate was directly added, it lacked the adsorption performance and loading of sepiolite, and its flame retardant and smoke suppressing effect was further reduced due to its agglomeration. Combining the test results of Comparative Example 3, when ammonium octamolate and sepiolite were directly added without composite addition, its effect was improved compared to Comparative Example 2, but it was still lower than that of Example 1. In Comparative Example 4, when only zinc borate was used as a flame retardant synergist, its flame retardant and smoke suppressing performance was further reduced.

[0061] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A low-smoke, low-halogen polyvinyl chloride cable material, characterized in that, Including the following parts by weight of raw materials: 60-80 parts polyvinyl chloride resin, 20-40 parts EVM500 rubber, 6-10 parts heat stabilizer, 0.1-0.5 parts antioxidant, 30-50 parts plasticizer, 0.5-1 part lubricant, 15-25 parts filler, 20-30 parts flame retardant and 8-15 parts flame retardant synergist and 0.5-1 part acrylate processing aid, wherein the flame retardant includes a mixture of aluminum hydroxide and magnesium hydroxide, and the flame retardant synergist includes zinc borate and ammonium octamolate-sepiolite complex; The ammonium octamolate-sepiolite composite was prepared by pretreating sepiolite by acid leaching and grafting with a vinylsilane coupling agent. Then, the pretreated sepiolite was dispersed in an aqueous solution of ammonium molybdate and dilute nitric acid was added dropwise to precipitate ammonium octamolate in situ on the surface of the pretreated sepiolite, thus obtaining a primary modified composite. The primary modified composite was then polymerized with acrylate monomers under the action of an initiator to obtain the ammonium octamolate-sepiolite composite.

2. The low-smoke, low-halogen polyvinyl chloride cable material according to claim 1, characterized in that: The ammonium octamolate-sepiolite complex was prepared by the following method: 1) Disperse sepiolite in 1-3 mol / L dilute hydrochloric acid, stir at 60-80℃ for 2-3 h, filter, wash with water and dry to obtain activated sepiolite; 2) Disperse activated sepiolite in an aqueous ethanol solution, add vinyltrimethoxysilane, reflux at 70-80℃ for 4-6 hours, filter, and obtain pretreated sepiolite; 3) Disperse the pretreated sepiolite in an aqueous solution of ammonium molybdate, ultrasonically disperse for 20-30 min, add dilute nitric acid to adjust the pH to 3-4, stir for 10-20 min, let stand, filter, wash and dry to obtain the initial modified complex. 4) Dissolve sodium dodecyl sulfate and polyoxyethylene ether in water, add acrylate monomers, stir for 30-40 minutes to form a monomer emulsion, then add the initial modified complex to 1 / 3-1 / 2 of the monomer emulsion, and disperse by ultrasonication to obtain the initial mixed reaction solution. Then, the remaining monomer emulsion is mixed with 1 / 3 to 1 / 2 of potassium persulfate solution, heated to 70-80℃, and stirred for 30-40 minutes to form a seed emulsion. The initial mixed reaction solution and the remaining potassium persulfate solution were added dropwise to the seed emulsion. The temperature was maintained at 70-80℃, and the reaction was carried out for 2-3 hours. After the reaction was completed, the mixture was cooled to room temperature, calcium chloride solution was added, and the mixture was filtered, washed with water, and dried to obtain the ammonium octamolybdate-sepiolite complex.

3. The low-smoke, low-halogen polyvinyl chloride cable material according to claim 2, characterized in that: When preparing the ammonium octamolate-sepiolite complex, in step 1), the mass concentration of sepiolite to dilute hydrochloric acid is 1:(4-6). In step 2), the amount of vinyltrimethoxysilane added is 5-8 wt% of the activated sepiolite, and the ethanol aqueous solution is prepared by mixing ethanol and water in a volume ratio of (7-9):(1-3), and the amount of ethanol aqueous solution added is 6-7 times the mass of the activated sepiolite. In step 3), the mass concentration of ammonium molybdate in the aqueous solution of ammonium molybdate is 3-4 wt%, and the mass ratio of ammonium molybdate to sepiolite is 1:(2-3). In step 4), the amount of ammonium dodecyl sulfate added is 2-5 wt% of the acrylate monomers, the amount of polyoxyethylene ether added is 1-2 wt% of the acrylate monomers, and the mass ratio of the acrylate monomers to the primary modified compound is (0.5-0.8):

1. The amount of water added is 8-10 times the mass of the primary modified compound. The amount of potassium persulfate added is 0.5-1 wt% of the acrylate monomers, and the mass concentration of the potassium persulfate solution is 5-10 wt%. The mass concentration of the calcium chloride solution is 5-10 wt%, and the amount of calcium chloride added is 1-3 wt% of the acrylate monomers.

4. The low-smoke, low-halogen polyvinyl chloride cable material according to claim 2, characterized in that: When preparing the ammonium octamolate-sepiolite complex, in step 3), the acrylate monomers are prepared by mixing methyl methacrylate and butyl acrylate in a mass ratio of (2-3):

1.

5. The low-smoke, low-halogen polyvinyl chloride cable material according to claim 2, characterized in that: In the preparation of the ammonium octamolate-sepiolite composite, in step 1), the activated sepiolite is first added to a 20-30 wt% aqueous solution of mercaptoacetic acid, the amount of mercaptoacetic acid added is 3-5 wt% of the activated sepiolite, stirred at 70-80℃ for 2-4 h, filtered, washed with water, and dried to obtain mercapto-modified sepiolite, and then the mercapto-modified sepiolite is subjected to step 2).

6. The low-smoke, low-halogen polyvinyl chloride cable material according to claim 2, characterized in that: In the preparation of the ammonium octamolate-sepiolite composite, in step 3), the aqueous solution of ammonium molybdate is first mixed with a treatment solution containing diethylenetriamine, PAMAM and maleic anhydride, and then pretreated sepiolite is added for ultrasonic dispersion. The treatment solution is prepared by mixing diethylenetriamine, PAMAM, maleic anhydride and water in a mass ratio of 1:(0.1-0.2):(0.1-0.2):(3-4), and the amount of treatment solution added is 0.3-0.4 times the mass of the pretreated sepiolite.

7. The low-smoke, low-halogen polyvinyl chloride cable material according to claim 1, characterized in that: The heat stabilizer used is calcium-zinc stabilizer, and the antioxidant used is antioxidant 1010. The lubricant used is stearic acid and oxidized polyethylene wax in a mass ratio of 1:(0.8-1.2).

8. The low-smoke, low-halogen polyvinyl chloride cable material according to claim 1, characterized in that: The filler material is selected from kaolin and montmorillonite in a mass ratio of 1:(0.8-1.2); The plasticizer is a mixture of triisooctyl acetyl citrate, trioctyl trimellitate and dioctyl sebacate in a mass ratio of 1:(0.6-0.8):(0.2-0.3).

9. The low-smoke, low-halogen polyvinyl chloride cable material according to claim 1, characterized in that: The flame retardant comprises a mixture of aluminum hydroxide and magnesium hydroxide in a mass ratio of 1:(1.8-2); The flame retardant synergist consists of a mixture of zinc borate and ammonium octamolate-sepiolite complex in a mass ratio of 1:(2-3).

10. A method for preparing a low-smoke, low-halogen polyvinyl chloride cable material as described in any one of claims 1-9, characterized in that: Includes the following steps: The raw materials are mixed according to the specified ratio, melted and mixed, then granulated and extruded to obtain low-smoke, low-halogen polyvinyl chloride cable material.

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