A preparation process of weather-resistant flame-retardant sheath material and optical cable thereof

Abstract

The present invention relates to the technical field of optical cable sheath materials, and discloses a preparation process of a weather-resistant flame-retardant sheath material and its optical cable, 100 parts by weight of ethylene-vinyl acetate copolymer EVA resin, 15-30 parts by weight of methyl vinyl silicone rubber, 2-8 parts by weight of EVA-based phosphorus-containing silicone oil flame retardant, 0.3-0.5 parts by weight of vulcanizing agent, etc. are added to a torque rheometer for mixing, then smelting, sheeting, thin pass, triangle packing, vulcanization, and weather-resistant flame-retardant sheath material are obtained. The trioxaphosphorus bicyclic structure and polysiloxane contained in the EVA-based phosphorus-containing silicone oil flame retardant of the present invention and the formation of phosphorus silicon flame retardant system improve the limiting oxygen index of the sheath material, reduce the heat release rate peak value and the total heat release amount, and show good flame retardant properties. At the same time, the EVA sheath material shows higher tensile strength and elongation at break, with better mechanical properties.

Description

Technical Field

[0001] The invention relates to the technical field of optical cable sheath materials, in particular to a preparation process of a weather-resistant and flame-retardant sheath material and an optical cable thereof. Background Art

[0002] Optical cables are mainly composed of sheath materials, insulation layers, cable cores, optical fibers, etc. The sheath materials protect and fix the cable cores, and the surface of the optical cable is subject to wear and corrosion. In recent years, the development of high-performance sheath materials for optical cables has become a research hotspot. Ethylene-vinyl acetate copolymer EVA resin has good chemical stability, excellent aging and ozone resistance, and shows good weather resistance. It also has high toughness and good elasticity, and is widely used in cables and optical cable sheath materials.

[0003] Improving the flame retardant properties of EVA resin is conducive to expanding its practical application in cable and optical cable sheath materials. The most common method is to add flame retardants, such as inorganic flame retardants, phosphorus flame retardants, phosphorus flame retardants, silicon flame retardants, etc. Silicone oil and other polysiloxane substances have excellent chemical stability, insulation and flame retardant properties and are widely used. Patent CN116218092B discloses a high temperature resistant and highly flame retardant cable, which uses acrylate imide DOPO monomer and tetramethyl divinyl disiloxane to undergo cross-linking polymerization to obtain DOPO-polysiloxane flame retardant copolymer, and the cross-linked polyethylene resin EVA resin is blended and modified to obtain a cable material with good flame retardancy and high temperature resistance. Compared with the invention, the present invention uses EVA-based phosphorus-containing silicone oil flame retardant to improve the mechanical properties and flame retardant properties of EVA sheath materials. Summary of the invention

[0004] (I) Technical problems to be solved: The present invention provides a preparation process of a weather-resistant flame-retardant sheath material and an optical cable thereof, which solves the problems of poor mechanical properties and poor flame retardant properties of EVA sheath materials used for optical cables.

[0005] (II) Technical solution: A preparation process of weather-resistant flame-retardant sheath material:

[0006] Step S1, add hydrogen-containing silicone oil and vinyl flame retardant to ethyl acetate, add Custer catalyst in nitrogen atmosphere, heat to 75-80°C, stir and condense reflux reaction for 5-8h, rotary evaporate, wash with methanol, and dry to obtain phosphorus-containing silicone oil flame retardant. The reaction formula is:

[0007]

[0008] Step S2, adding phosphorus-containing silicone oil flame retardant, maleic anhydride grafted EVA, and p-toluenesulfonic acid to xylene, heating to 125-135° C., stirring for reaction for 6-12 hours, rotary evaporation, and drying to obtain EVA-based phosphorus-containing silicone oil flame retardant.

[0009] Step S3, adding 100 parts by weight of ethylene-vinyl acetate copolymer EVA resin, 15-30 parts by weight of methyl vinyl silicone rubber, 2-8 parts by weight of EVA-based phosphorus-containing silicone oil flame retardant, 0.3-0.6 parts by weight of antioxidant 1010, 0.2-0.3 parts by weight of auxiliary agent zinc stearate, and 0.3-0.5 parts by weight of vulcanizing agent 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane into a torque rheometer for mixing, then refining in an open mill, followed by sheeting, thinning, and triangle bagging, and finally vulcanizing in a flat vulcanizer to obtain a weather-resistant flame-retardant sheath material.

[0010] Preferably, in step S1, the mass of the vinyl flame retardant and the Custer catalyst are 20-40% and 0.03-0.08% of the mass of the hydrogen-containing silicone oil, respectively.

[0011] Preferably, in step S2, the mass of maleic anhydride grafted EVA and p-toluenesulfonic acid are 4-10% and 0.15-0.5% of the mass of the phosphorus-containing silicone oil flame retardant, respectively.

[0012] Preferably, the mixing temperature in step S3 is 110-120° C. and the mixing time is 20-30 min; and the vulcanization process is performed at a pressure of 10-12 MPa and a temperature of 165-175° C. for 10-15 min.

[0013] Preferably, the preparation process of the vinyl flame retardant is: add 100 parts by weight of allyl glycidyl ether, 170-190 parts by weight of 1-oxo-4-hydroxymethyl-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane, 9-12 parts by weight of catalyst, 3-4 parts by weight of inhibitor 2,6-di-tert-butyl-p-cresol to toluene, heat to 80-110°C, condense and reflux for 6-18h, rotary evaporate, wash with water, and recrystallize the product with ethanol to obtain the vinyl flame retardant. The reaction formula is:

[0014]

[0015] Preferably, the catalyst is tetraethylphosphine bromide or tetrabutylphosphine bromide.

[0016] Preferably, an optical cable has an outer sheath material made of a weather-resistant and flame-retardant sheath material.

[0017] (III) Technical effect: The present invention uses tetrabutylphosphonium bromide or the like as a catalyst to react allyl glycidyl ether and 1-oxo-4-hydroxymethyl-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane to obtain a vinyl flame retardant containing hydroxyl groups, which is then subjected to a hydrosilylation reaction with hydrogen-containing silicone oil. The hydroxyl groups of the flame retardant react with the anhydride groups of maleic anhydride-grafted EVA to obtain an EVA-based phosphorus-containing silicone oil flame retardant.

[0018] The present invention uses EVA resin as the base of the optical cable sheath material, and mixes and vulcanizes with methyl vinyl silicone rubber, EVA-based phosphorus-containing silicone oil flame retardant, antioxidant, vulcanizing agent, etc. to obtain a weather-resistant flame-retardant sheath material for optical cable. The trioxaphosphorus bicyclic structure and polysiloxane contained in the EVA-based phosphorus-containing silicone oil flame retardant form a phosphorus-silicon flame retardant system. During combustion, the phosphate structure is pyrolyzed to generate phosphorus-containing free radicals, which can capture the combustion chain free radicals and inhibit the combustion process. At the same time, the phosphate structure is pyrolyzed to generate phosphoric acid substances, which can dehydrate the EVA sheath material base to form a carbon layer. The polysiloxane is pyrolyzed to generate inorganic silicon substances, which are combined with the carbon layer to isolate oxygen, prevent heat from being transferred to the material base, and prevent smoke from escaping. The limiting oxygen index of the sheath material is improved, the peak value of the heat release rate and the total heat release amount are reduced, and good flame retardant performance is shown.

[0019] The EVA-based phosphorus-containing silicone oil flame retardant of the invention contains a polysiloxane molecular chain similar to methyl vinyl silicone rubber, and a side chain is grafted with an EVA molecular chain identical to an EVA resin, so that the EVA-based phosphorus-containing silicone oil flame retardant can play the role of a compatibilizer, improve the compatibility between the methyl vinyl silicone rubber and the EVA resin, enable the silicone rubber to play a better reinforcing role, improve the tensile strength and elongation at break of the EVA sheath material, and have better mechanical properties. DETAILED DESCRIPTION

[0020] For the convenience of understanding the present invention, the present invention will be described in more detail below in conjunction with specific examples. Preferred embodiments of the present invention are provided in the examples. However, the present invention can be implemented in many different forms and is not limited to the examples described in this specification. On the contrary, the purpose of providing these examples is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0021] The hydrogen-containing silicone oil of the present invention has a hydrogen content of 1.6%, Jiangxi Hongshi New Materials. Custer catalyst, platinum content 5000ppm, Dongguan Beiteli New Materials. Maleic anhydride grafted EVA, brand E418, Dongguan Shangyi Plastics. Ethylene-vinyl acetate copolymer EVA resin, brand 53021, Dongguan Shangyi Plastics. Methyl vinyl silicone rubber, Hubei Langbowan Biomedicine.

[0022] Example 1

[0023] (1) Add 5 g of allyl glycidyl ether, 9.5 g of 1-oxo-4-hydroxymethyl-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane (CAS No. 5301-78), 0.45 g of tetrabutylphosphonium bromide (CAS No. 3115-68-2), and 0.15 g of inhibitor 2,6-di-tert-butyl-p-cresol (CAS No. 128-37-0) to 200 mL of toluene, heat to 110°C, stir and reflux for 6 h, evaporate by rotary evaporation, wash with water, and recrystallize the product with ethanol to obtain a vinyl flame retardant.

[0024] (2) Add 30 g of hydrogenated silicone oil and 8 g of vinyl flame retardant to 40 mL of ethyl acetate, add 13 mg of Castel catalyst in a nitrogen atmosphere, heat to 80 °C, stir and condense under reflux for 5 h, rotary evaporate, wash with methanol, and dry to obtain phosphorus-containing silicone oil flame retardant.

[0025] (3) Add 20 g of phosphorus-containing silicone oil flame retardant, 1.4 g of maleic anhydride grafted EVA, and 0.06 g of p-toluenesulfonic acid into 250 mL of xylene, heat to 125 °C, stir to react for 12 h, rotary evaporate, and dry to obtain EVA-based phosphorus-containing silicone oil flame retardant.

[0026] (4) 1 kg of ethylene-vinyl acetate copolymer EVA resin, 150 g of methyl vinyl silicone rubber, 20 g of EVA-based phosphorus-containing silicone oil flame retardant, 4 g of antioxidant 1010, 2 g of auxiliary agent zinc stearate, and 3 g of vulcanizing agent 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane were added to a torque rheometer, mixed at 110°C for 30 min, and then refined in an open mixing mill, followed by sheeting, thinning, and triangular packaging. Finally, the material was vulcanized in a flat vulcanizer at 170°C for 10 min under a pressure of 10 MPa to obtain a weather-resistant flame-retardant sheath material.

[0027] Example 2

[0028] (1) Add 5 g of allyl glycidyl ether, 8.5 g of 1-oxo-4-hydroxymethyl-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane, 0.52 g of tetrabutylphosphonium bromide, and 0.2 g of inhibitor 2,6-di-tert-butyl-p-cresol to 150 mL of toluene, heat to 80°C, stir to react for 18 h, rotary evaporate, wash with water, and recrystallize the product with ethanol to obtain a vinyl flame retardant.

[0029] (2) Add 30 g of hydrogenated silicone oil and 6 g of vinyl flame retardant to 40 mL of ethyl acetate, add 9 mg of Castel catalyst in a nitrogen atmosphere, heat to 75 °C, stir and condense under reflux for 8 h, rotary evaporate, wash with methanol, and dry to obtain phosphorus-containing silicone oil flame retardant.

[0030] (3) Add 20 g of phosphorus-containing silicone oil flame retardant, 0.8 g of maleic anhydride grafted EVA, and 0.03 g of p-toluenesulfonic acid into 200 mL of xylene, heat to 130 °C, stir and react for 6 h, rotary evaporate, and dry to obtain EVA-based phosphorus-containing silicone oil flame retardant.

[0031] (4) 1 kg of ethylene-vinyl acetate copolymer EVA resin, 200 g of methyl vinyl silicone rubber, 20 g of EVA-based phosphorus-containing silicone oil flame retardant, 6 g of antioxidant 1010, 3 g of auxiliary agent zinc stearate, and 5 g of vulcanizing agent 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane were added to a torque rheometer, mixed at 110°C for 30 min, and then refined in an open mixing mill, followed by sheeting, thinning, and triangular packaging. Finally, the material was vulcanized in a flat vulcanizer at a pressure of 10 MPa and 175°C for 10 min to obtain a weather-resistant flame-retardant sheath material.

[0032] Example 3

[0033] (1) Add 5 g of allyl glycidyl ether, 8.8 g of 1-oxo-4-hydroxymethyl-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane, 0.6 g of tetraethylphosphine bromide, and 0.15 g of inhibitor 2,6-di-tert-butyl-p-cresol to 150 mL of toluene, heat to 90°C, stir to react for 12 h, rotary evaporate, wash with water, and recrystallize the product with ethanol to obtain a vinyl flame retardant.

[0034] (2) Add 30 g of hydrogenated silicone oil and 12 g of vinyl flame retardant to 50 mL of ethyl acetate, add 24 mg of Castel catalyst in a nitrogen atmosphere, heat to 80 °C, stir and condense under reflux for 6 h, rotary evaporate, wash with methanol, and dry to obtain phosphorus-containing silicone oil flame retardant.

[0035] (3) Add 20 g of phosphorus-containing silicone oil flame retardant, 2 g of maleic anhydride grafted EVA, and 0.1 g of p-toluenesulfonic acid into 300 mL of xylene, heat to 135 °C, stir and react for 8 h, rotary evaporate, and dry to obtain EVA-based phosphorus-containing silicone oil flame retardant.

[0036] (4) 1 kg of ethylene-vinyl acetate copolymer EVA resin, 300 g of methyl vinyl silicone rubber, 20 g of EVA-based phosphorus-containing silicone oil flame retardant, 3 g of antioxidant 1010, 3 g of auxiliary agent zinc stearate, and 5 g of vulcanizing agent 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane were added to a torque rheometer, mixed at 120°C for 20 min, and then refined in an open mixing mill, followed by sheeting, thinning, and triangle packing. Finally, in a flat vulcanizer, vulcanized at 165°C for 15 min under a pressure of 12 MPa to obtain a weather-resistant flame-retardant sheath material.

[0037] Example 4

[0038] (1) 1 kg of ethylene-vinyl acetate copolymer EVA resin, 150 g of methyl vinyl silicone rubber, 50 g of EVA-based phosphorus-containing silicone oil flame retardant (prepared in Example 1), 4 g of antioxidant 1010, 2 g of auxiliary agent zinc stearate, and 3 g of vulcanizing agent 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane were added to a torque rheometer, mixed at 110° C. for 30 min, and then refined in an open mill, followed by sheeting, thinning, and triangular bagging. Finally, in a flat vulcanizer, under a pressure of 10 MPa, vulcanized at 170° C. for 10 min to obtain a weather-resistant flame-retardant sheath material.

[0039] Example 5

[0040] (1) 1 kg of ethylene-vinyl acetate copolymer EVA resin, 150 g of methyl vinyl silicone rubber, 80 g of EVA-based phosphorus-containing silicone oil flame retardant (prepared in Example 1), 4 g of antioxidant 1010, 2 g of auxiliary agent zinc stearate, and 3 g of vulcanizing agent 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane were added to a torque rheometer, mixed at 110° C. for 30 min, and then refined in an open mill, followed by sheeting, thinning, and triangular bagging. Finally, in a flat vulcanizer, under a pressure of 10 MPa, vulcanized at 170° C. for 10 min to obtain a weather-resistant flame-retardant sheath material.

[0041] Comparative Example 1

[0042] (1) 1 kg of ethylene-vinyl acetate copolymer EVA resin, 4 g of antioxidant 1010, 2 g of auxiliary agent zinc stearate, and 3 g of vulcanizing agent 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane were added to a torque rheometer, mixed at 110°C for 30 min, and then refined in an open mixing mill, followed by sheeting, thinning, and triangular packaging. Finally, in a flat vulcanizer, vulcanized at 170°C for 10 min under a pressure of 10 MPa to obtain a weather-resistant flame-retardant sheath material.

[0043] Comparative Example 2

[0044] (1) 1 kg of ethylene-vinyl acetate copolymer EVA resin, 150 g of methyl vinyl silicone rubber, 4 g of antioxidant 1010, 2 g of auxiliary agent zinc stearate, and 3 g of vulcanizing agent 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane were added to a torque rheometer, mixed at 110°C for 30 min, and then refined in an open mixing mill, followed by sheeting, thinning, and triangular packaging. Finally, in a flat vulcanizer, vulcanized at 170°C for 10 min under a pressure of 10 MPa to obtain a weather-resistant flame-retardant sheath material.

[0045] Comparative Example 3

[0046] (1) 1 kg of ethylene-vinyl acetate copolymer EVA resin, 150 g of methyl vinyl silicone rubber, 20 g of hydrogenated silicone oil, 4 g of antioxidant 1010, 2 g of auxiliary agent zinc stearate, and 3 g of vulcanizing agent 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane were added to a torque rheometer, mixed at 110°C for 30 min, and then refined in an open mill, followed by sheeting, thinning, and triangular packaging. Finally, in a flat vulcanizer, vulcanized at 170°C for 10 min under a pressure of 10 MPa to obtain a weather-resistant flame-retardant sheath material.

[0047] Comparative Example 4

[0048] (1) 1 kg of ethylene-vinyl acetate copolymer EVA resin, 150 g of methyl vinyl silicone rubber, 20 g of phosphorus-containing silicone oil flame retardant (prepared in Example 1), 4 g of antioxidant 1010, 2 g of auxiliary agent zinc stearate, and 3 g of vulcanizing agent 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane were added to a torque rheometer, mixed at 110° C. for 30 min, and then refined in an open mill, followed by sheeting, thinning, and triangle bagging. Finally, in a flat vulcanizer, under a pressure of 10 MPa, vulcanized at 170° C. for 10 min to obtain a weather-resistant flame-retardant sheath material.

[0049] The tensile properties of the sheath material are tested according to GB / T 1040.1-2018 method.

[0050] The limiting oxygen index of the sheath material is tested according to GB / T 2406.1-2008 method.

[0051] The combustion performance of the jacket material was tested using a cone calorimeter with a thermal radiation intensity of 35kW / m 2 The sample size is 10cm×8cm×0.2cm.

[0052] Table 1 Sheath material performance test

[0053]

[0054] As can be seen from Table 1, the EVA sheath material of Comparative Example 1 does not contain methyl vinyl silicone rubber and EVA-based phosphorus-containing silicone oil flame retardant, the sheath material has low tensile strength and elongation at break, poor mechanical properties, and a limiting oxygen index of only 17.6%, a large heat release rate peak and a large total heat release, and very poor flame retardancy.

[0055] In comparative example 2, methyl vinyl silicone rubber was added, and the tensile strength of the EVA sheath material increased slightly, and the elongation at break tended to decrease, the mechanical properties were poor, and the limiting oxygen index was low, the peak heat release rate and the total heat release were large, and the flame retardancy was poor.

[0056] In comparative example 3, hydrogen-containing silicone oil was added, and the tensile strength, elongation at break, and limiting oxygen index of the EVA sheath material were low, the peak value of the heat release rate, and the total heat release amount hardly changed, and the mechanical properties and flame retardant properties were poor.

[0057] In Example 1-5, EVA-based phosphorus-containing silicone oil flame retardant was added, and the limiting oxygen index of the EVA sheath material increased to 27.4-29.8%, and the peak heat release rate and total heat release amount decreased significantly, and the flame retardant performance changed. This is because the trioxaphosphorus bicyclic structure ( ) and polysiloxane form a phosphorus-silicon flame retardant system. During combustion, the phosphate structure is pyrolyzed to generate phosphorus-containing free radicals, which can capture the combustion chain free radicals and inhibit the combustion process. At the same time, the phosphate structure is pyrolyzed to generate phosphoric acid substances, which can dehydrate the EVA sheath material matrix to form a carbon layer. The polysiloxane is pyrolyzed to generate inorganic silicon substances, which are combined with the carbon layer to isolate oxygen, prevent heat from being transferred to the material matrix, and prevent smoke from escaping, thereby showing good flame retardant properties. In addition, the tensile strength and elongation at break of the EVA sheath material are significantly improved. This is because the EVA-based phosphorus-containing silicone oil flame retardant contains a polysiloxane molecular chain similar to that of methyl vinyl silicone rubber, and the side chain is grafted with the same EVA molecular chain as that of the EVA resin, so that the EVA-based phosphorus-containing silicone oil flame retardant can act as a compatibilizer, improve the compatibility between methyl vinyl silicone rubber and EVA resin, and the silicone rubber can play a good reinforcing role, improve the tensile strength and elongation at break of the EVA sheath material, and have better mechanical properties.

[0058] In Comparative Example 4, phosphorus-containing silicone oil flame retardant was added, the limiting oxygen index of the EVA sheath material increased, the peak heat release rate and the total heat release were significantly reduced, and the flame retardant performance was very good. However, the phosphorus-containing silicone oil flame retardant does not contain EVA molecular chains, and has poor compatibility with EVA resin. It also does not play a role in toughening the compatibility between methyl vinyl silicone rubber and EVA resin. The tensile strength and elongation at break of the EVA sheath material are low.

Claims

1. A preparation process of a weather-resistant flame-retardant sheath material, characterized in that: The preparation process comprises the following steps: Step S1, adding hydrogen-containing silicone oil to ethyl acetate, the structural formula is Vinyl flame retardant, adding Custer catalyst in nitrogen atmosphere, heating to reaction temperature, stirring reaction, rotary evaporation, washing, drying, to obtain phosphorus-containing silicone oil flame retardant; Step S2, adding phosphorus-containing silicone oil flame retardant, maleic anhydride grafted EVA, and p-toluenesulfonic acid to xylene, heating to a reaction temperature, stirring for reaction, rotary evaporation, and drying to obtain an EVA-based phosphorus-containing silicone oil flame retardant; Step S3, adding 100 parts by weight of ethylene-vinyl acetate copolymer EVA resin, 15-30 parts by weight of methyl vinyl silicone rubber, 2-8 parts by weight of EVA-based phosphorus-containing silicone oil flame retardant, 0.3-0.6 parts by weight of antioxidant, 0.2-0.3 parts by weight of auxiliary agent, and 0.3-0.5 parts by weight of vulcanizing agent into a torque rheometer for mixing, then mixing in an open mixing mill, followed by sheeting, thinning, and triangle bagging, and finally vulcanizing in a flat vulcanizer to obtain a weather-resistant flame-retardant sheath material.

2. The preparation process of the weather-resistant flame-retardant sheath material according to claim 1, characterized in that: In the step S1, the mass of the vinyl flame retardant and the Custer catalyst are respectively 20-40% and 0.03-0.08% of the mass of the hydrogen-containing silicone oil.

3. The preparation process of the weather-resistant flame-retardant sheath material according to claim 1, characterized in that: In step S1, the reaction temperature is 75-80° C. and the reaction time is 5-8 hours.

4. The preparation process of the weather-resistant flame-retardant sheath material according to claim 1, characterized in that: In step S2, the mass of maleic anhydride grafted EVA and p-toluenesulfonic acid are 4-10% and 0.15-0.5% of the mass of the phosphorus-containing silicone oil flame retardant, respectively.

5. The preparation process of the weather-resistant flame-retardant sheath material according to claim 1, characterized in that: In step S2, the reaction temperature is 125-135° C. and the reaction time is 6-12 h.

6. The process for preparing the weather-resistant flame-retardant sheath material according to claim 1, characterized in that: In step S3, the antioxidant is antioxidant 1010, the auxiliary agent is zinc stearate, and the vulcanizing agent is 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane.

7. The preparation process of the weather-resistant flame-retardant sheath material according to claim 1, characterized in that: The mixing temperature in step S3 is 110-120° C. and the mixing time is 20-30 min. The vulcanization process is performed at a pressure of 10-12 MPa and a temperature of 165-175° C. for 10-15 min.

8. The process for preparing the weather-resistant flame-retardant sheath material according to claim 1, characterized in that: The preparation process of the vinyl flame retardant comprises the following steps: adding 100 parts by weight of allyl glycidyl ether, 170-190 parts by weight of 1-oxo-4-hydroxymethyl-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane, 9-12 parts by weight of a catalyst, and 3-4 parts by weight of a polymerization inhibitor 2,6-di-tert-butyl-p-cresol into toluene, heating the mixture to 80-110° C., condensing and refluxing the mixture for 6-18 hours, rotary evaporation, washing, and recrystallization to obtain the vinyl flame retardant.

9. The process for preparing the weather-resistant flame-retardant sheath material according to claim 8, characterized in that: The catalyst is tetraethylphosphine bromide or tetrabutylphosphine bromide.

10. An optical cable, characterized in that: The outer sheath material of the optical cable is a weather-resistant and flame-retardant sheath material obtained by the preparation process described in any one of claims 1 to 9.

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