Synthesis process of a low refractive index optical fiber cladding material composition and its applications

Abstract

This invention discloses a synthesis process and application of a low-refractive-index optical fiber cladding material composition, relating to the field of optical fiber coating technology. The low-refractive-index optical fiber cladding material composition is obtained by polymerizing a mixture of fluorinated acrylate, acrylate, acrylic acid, fluorinated polyether acrylate, compatibilizer monomers, and solvent under the action of an initiator. This invention prepares an optical fiber cladding material composition that combines low refractive index, high tensile strength, and high hardness by compounding a low-refractive-index fluorinated polyether acrylate with a compatibilizer monomer and optimizing the proportions of other raw materials.

Description

Technical Field

[0001] This invention relates to the field of optical fiber coating technology, and more specifically to a synthesis process and application of a low refractive index optical fiber cladding material composition. Background Technology

[0002] Fiber lasers have developed rapidly and are widely used in various fields such as optical data storage, optical communication, sensing technology, spectroscopy, and medical applications. To protect the optical fiber from external environmental influences and maintain sufficient mechanical strength and optical performance, a multi-layered protective system is formed during fiber drawing, consisting of a soft buffer layer and a tough, abrasion-resistant, and chemical-resistant protective layer. For fibers used in fiber lasers, since the coating itself participates in the transmission of pump light, the refractive index of the coating directly determines the power level of the laser and the quality level of the fiber. Generally, the refractive index of the inner fiber coating after curing should be ≤1.380.

[0003] Fluoropolymers possess excellent properties of "three highs" (high weather resistance, high heat resistance, and high stability) and "two repellencies" (hydrophobicity and oleophobicity). Furthermore, due to the high electronegativity and low polarizability of fluorine, the refractive index of these materials is significantly lower than that of ordinary materials. Therefore, fluorinated materials are commonly used as fiber coatings in fiber lasers. Currently, the main method to reduce the refractive index of the fiber coating is by blending fluorinated acrylate monomers with other host resins. However, these host resins themselves have relatively high refractive indices, requiring the addition of large amounts of fluorinated acrylate monomers to effectively reduce the refractive index. This not only makes it difficult to significantly reduce the refractive index but also affects the performance of the cured coating and increases the manufacturing cost. In addition, the types of fluorinated raw materials used to synthesize fluorinated acrylates are limited and expensive, their compatibility with non-fluorinated raw materials is poor, and their interfacial bonding with optical fiber glass fibers is insufficient, thus restricting the use of existing fluorinated acrylate materials in optical fiber cladding materials.

[0004] Therefore, to solve the problems existing in the practical use of fluorinated acrylates, we need to further explore the design and preparation methods of fluorinated acrylate materials in order to improve the transmission efficiency and long-term stability of optical fibers and provide strong technical support for the development of the optical fiber communication industry. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a synthesis process for a low-refractive-index optical fiber cladding material composition and its application.

[0006] The objective of this invention can be achieved through the following technical solutions: A low-refractive-index optical fiber cladding material composition comprises the following raw materials in parts by weight: 10-20 parts of fluorinated acrylate, 15-30 parts of acrylate, 3-5 parts of acrylic acid, 10-20 parts of fluorinated polyether acrylate, 2-4 parts of compatibilizer monomer, 10-20 parts of solvent, and 0.5-1 part of initiator. Furthermore, the fluorinated acrylate is obtained by mixing dodecafluoroheptyl methacrylate, trifluoroethyl methacrylate, and hexafluorobutyl methacrylate in a mass ratio of 1:2:0.6-0.8; Furthermore, the acrylate is obtained by mixing methyl methacrylate and butyl acrylate in a mass ratio of 2:1-1.5; Further, the solvent is a mixture of butyl acetate, ethyl acetate, and methyl acetate in a volume ratio of 2:1:0.5-1; Furthermore, the initiator is benzoyl peroxide.

[0007] A process for synthesizing a low-refractive-index optical fiber cladding material composition includes the following steps: Weigh out fluorinated acrylate, acrylate, acrylic acid, fluorinated polyether acrylate, compatibilizer and solvent according to the formula, stir and mix them in a protective gas atmosphere at room temperature, add initiator, stir and heat, continue stirring to obtain a low refractive index optical fiber cladding material composition. Furthermore, the mixing time at room temperature is 1-1.5 hours, and after mixing, the mixture is heated to a temperature of 70-75°C and the mixing time is continued for 3-4 hours.

[0008] The present invention also provides an application of a low refractive index optical fiber cladding material composition, which involves coating the low refractive index optical fiber cladding material composition onto the surface of an optical fiber and then curing it with ultraviolet light to obtain the optical fiber cladding material.

[0009] The fluorinated polyether acrylate is prepared by the following steps: Step A1: Mix small molecule fluorools, epichlorohydrin, and tetrahydrofuran, add a catalyst, and heat and stir in a protective gas atmosphere to obtain a fluorinated epoxy compound. Step A2: Mix the quaternary ammonium salt catalyst and isopropanol, add the fluorinated epoxy compound, heat and reflux with stirring, add the fluorinated epoxy compound, and continue stirring to obtain the fluorinated polyether polyol. Step A3: Add the dicarboxylic acid to thionyl chloride, add DMF dropwise, and stir to obtain diacyl chloride; mix the fluorinated polyether polyol, diacyl chloride, and dichloromethane, heat and reflux under a protective gas atmosphere, adjust the pH, and obtain the chain extension product of the fluorinated polyether polyol. Step A4: After mixing and stirring the chain extension product of the fluorinated polyether polyol and 1,4-dioxane, add the acyl chloride containing terminal double bonds, heat and reflux and stir to obtain the fluorinated polyether acrylate.

[0010] The preparation method of the fluorinated polyether acrylate includes the following specific steps: Step A1: Add small molecule fluorools and epichlorohydrin to tetrahydrofuran and stir for 30-35 min. Add catalyst and reflux and stir at 50-70℃ for 4-5 h in a protective gas atmosphere. Rotary evaporate, adjust pH to neutral, extract and dry to obtain fluorinated epoxy compounds. Furthermore, the molar ratio of the small molecule fluorool to epichlorohydrin is 1:1-2; the ratio of the total mass of the small molecule fluorool and epichlorohydrin to the volume of tetrahydrofuran is 1g:2-2.5mL; and the amount of catalyst used is 2-4% of the mass of the small molecule fluorool. Furthermore, the small molecule fluorool is selected from one of hexafluoroisopropanol, octafluoropentanol, trifluoroethanol, hexafluorobutanol, and perfluorohexylethanol; the catalyst is one of sodium hydroxide, potassium hydroxide, and boron trifluoride diethyl ether complex. In step A1, small molecule fluorools react with epichlorohydrin to obtain fluorinated epoxy compounds; Step A2: Mix the quaternary ammonium salt catalyst and isopropanol and stir for 10-15 min. Add the fluorinated epoxy compound, heat to 100-110℃, reflux and stir at normal pressure for 1-2 h, add the fluorinated epoxy compound, continue stirring for 1-2 h, and rotary evaporate to obtain the fluorinated polyether polyol. Furthermore, the ratio of isopropanol to fluorinated epoxy compound is 10 mL: 5-6 g, and the amount of quaternary ammonium salt catalyst is 1-1.5% of the mass of fluorinated epoxy compound; the fluorinated epoxy compound is added in two parts, with the mass ratio of the first and second additions being 1:1; the quaternary ammonium salt catalyst is selected from one of benzyltrimethylammonium chloride, tetrabutylammonium bromide, and hexadecyltrimethylammonium chloride; Furthermore, the molecular weight of the fluorinated polyether polyol is 2000-2500; In step A2, the fluorinated epoxy compound undergoes ring-opening polymerization under quaternary ammonium salt catalysis to obtain a fluorinated polyether polyol; Step A3: Add the dicarboxylic acid to thionyl chloride, add DMF dropwise, and stir at room temperature for 3-4 hours to obtain diacyl chloride; mix the fluorinated polyether polyol, diacyl chloride, and dichloromethane, heat to 60-80℃ in a protective gas atmosphere, reflux and stir for 2-3 hours, adjust the pH to neutral, and rotary evaporate to obtain the chain-extended product of the fluorinated polyether polyol; Furthermore, the molar ratio of the dicarboxylic acid, sulfoxide, and DMF is 1:2.5-3:0.08-0.1; the dicarboxylic acid is selected from one of octanoic acid, adipic acid, and succinic acid. Furthermore, the ratio of the fluorinated polyether polyol, diacyl chloride, and dichloromethane is 10-13g:0.8-1g:45-55mL; In step A3, the dicarboxylic acid reacts with thionyl chloride to obtain diacyl chloride, and the fluorinated polyether polyol reacts with the diacyl chloride to obtain the chain extension product of the fluorinated polyether polyol with hydroxyl terminus. Step A4: Mix the chain extension product of fluorinated polyether polyol and 1,4-dioxane and stir for 30-40 min, add acyl chloride containing terminal double bonds, and reflux and stir at 70-80℃ for 6-7 h to obtain fluorinated polyether acrylate. Furthermore, the ratio of the chain extender of the fluorinated polyether polyol, 1,4-dioxane, and the acyl chloride containing terminal double bonds is 12-14g:65-75mL:1.1-1.3g; the acyl chloride containing terminal double bonds is acryloyl chloride or methacryloyl chloride. In step A4, the chain extension product of the fluorinated polyether polyol reacts with an acyl chloride containing terminal double bonds to obtain fluorinated polyether acrylate.

[0011] The compatibilizing monomer is prepared by the following steps: Glycidyl methacrylate, an amino-containing compound, and DMAC were mixed, heated, and stirred to obtain a compatibilizing monomer.

[0012] Furthermore, the heating temperature is 40-45℃, and the stirring time is 2-3 hours; Further, the ratio of glycidyl methacrylate, amino-containing compound, and DMAC is 15-17g:9-10g:35-45mL; the amino-containing compound is obtained by mixing amino-containing dicarboxynitrile and amino-containing nano-silica in a mass ratio of 1:1-1.5. Furthermore, the preparation method of the amino-containing dicarboxynitrile is as follows: mixing nitrophthalonitrile, acetonitrile, and a reducing agent, and stirring at room temperature to obtain amino-containing dicarboxynitrile; Furthermore, the stirring time at room temperature is 2-3 hours.

[0013] Further, the ratio of the nitrophthalonitrile, acetonitrile, and reducing agent is 9-10g: 20-25mL: 25-30mL; the nitrophthalonitrile is 4-nitrophthalonitrile or 3-nitrophthalonitrile; the reducing agent is a sodium dithionite solution with a mass fraction of 35-40%. Furthermore, the preparation method of the amino-containing nano-silica is as follows: nano-silica, methanol, water, and amino-containing silane coupling agent are mixed and stirred at room temperature to obtain amino-containing nano-silica; Furthermore, the stirring time at room temperature is 1-2 hours; Furthermore, the ratio of the nano-silica, methanol, water, and aminosilane coupling agent is 10-12g:40-45mL:10-15mL:0.25-0.3g; the aminosilane coupling agent is KH550 or KH540. In the preparation of compatibilizing monomers, glycidyl methacrylate is reacted with an amino-containing compound to obtain a monomer containing a tertiary amine, a secondary alcohol, dimethyl nitrile, nano-silica, and terminal double bonds, which is the compatibilizing monomer.

[0014] The beneficial effects of this invention are: 1. This invention discloses a synthesis process and application of a low-refractive-index optical fiber cladding material composition. The low-refractive-index optical fiber cladding material composition is obtained by polymerizing a mixture of fluorinated acrylate, acrylate, acrylic acid, fluorinated polyether acrylate, compatibilizer monomer and solvent under the action of an initiator. Through the reasonable proportion of each raw material, an optical fiber cladding material composition with excellent comprehensive performance is prepared.

[0015] 2. The fluorinated polyether acrylate used in this invention is obtained by epoxidation of small molecule fluorinated alcohols to obtain fluorinated epoxy compounds. The fluorinated epoxy compounds are then ring-opened polymerized under the action of quaternary ammonium salt catalysts to obtain fluorinated polyether polyols. After chain extension by reacting the fluorinated polyether polyols with diacyl chlorides, they are then reacted with acyl chlorides containing terminal double bonds to obtain the final product. The preparation method is simple and has a lower refractive index compared to fluorinated acrylates, which enhances the mechanical properties of the material. It avoids the need to use a large amount of fluorinated acrylates to reduce the refractive index, thus reducing costs and providing a new approach for the preparation of low refractive index fluorinated resin coatings.

[0016] 3. The compatibilizing monomer used in this invention is a monomer containing tertiary amine, secondary alcohol, dimethyl methacrylate, nano-silica, and terminal double bonds, obtained by reacting glycidyl methacrylate with an amino-containing compound. The amino-containing compound is a mixture of amino-containing dimethyl methacrylate and amino-containing nano-silica. Secondary alcohols and dimethyl nitrile form chemical crosslinks with polar groups such as hydroxyl groups on the surface of optical fiber glass fibers. Nano-silica fills the microscopic pores of the cladding material and glass fibers through nanoscale effects. Their synergistic effect significantly enhances the interfacial bonding force between the low-refractive-index optical fiber cladding material composition and the glass fibers. Nano-silica, together with fluorinated acrylates and fluorinated polyether acrylates, synergistically reduces the refractive index of the cladding material composition, improving the transmission stability of optical signals. The tertiary amine in the compatibilizer monomer can accelerate the decomposition of benzoyl peroxide and promote the polymerization reaction of fluorinated acrylates, acrylates, acrylic acid, fluorinated polyether acrylates, and compatibilizer monomers without the need for additional accelerators. It has good compatibility with fluorinated acrylates, acrylates, acrylic acid, and fluorinated polyether acrylates, enabling low-cost and rapid polymerization, which is very beneficial for the industrial-scale preparation of low-refractive-index optical fiber cladding material compositions. Detailed Implementation

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Example 1 Fluorinated polyether acrylates are prepared by the following specific steps: Step A1: Add hexafluoroisopropanol and epichlorohydrin to tetrahydrofuran and stir for 30 min. Add sodium hydroxide and reflux at 50 °C for 4 h under a nitrogen atmosphere. Rotary evaporate at 40 °C. Adjust the pH to neutral with a 20% sodium hydroxide solution. Extract with ethyl acetate and dry with anhydrous sodium sulfate to obtain a fluorinated epoxy compound. The molar ratio of hexafluoroisopropanol to epichlorohydrin is 1:1. The ratio of the total mass of hexafluoroisopropanol and epichlorohydrin to the volume of tetrahydrofuran is 1 g: 2 mL. The amount of sodium hydroxide used is 2% of the mass of hexafluoroisopropanol.

[0019] Step A2: Mix benzyltrimethylammonium chloride and isopropanol and stir for 10 min. Add the fluorinated epoxy compound, heat to 100℃, reflux and stir at normal pressure for 1 h. Add the fluorinated epoxy compound again and continue stirring for 1 h. Rotary evaporate at 40℃ to obtain the fluorinated polyether polyol. The ratio of isopropanol to fluorinated epoxy compound is 10 mL: 5 g, and the amount of benzyltrimethylammonium chloride is 1% of the mass of the fluorinated epoxy compound. The fluorinated epoxy compound is added in two parts, with a mass ratio of 1:1 between the first and second additions. The molecular weight of the fluorinated polyether polyol is 2000. Step A3: Add octanoic acid to sulfoxide, add DMF dropwise, and stir at room temperature for 3 hours to obtain diacyl chloride; mix fluorinated polyether polyol, diacyl chloride, and dichloromethane, heat to 60°C in a nitrogen atmosphere, reflux and stir for 2 hours, adjust the pH to neutral with 10% sodium hydroxide solution, and rotary evaporate at 40°C to obtain the chain-extended product of fluorinated polyether polyol; the molar ratio of octanoic acid, sulfoxide, and DMF is 1:2.5:0.08; the molar ratio of fluorinated polyether polyol, diacyl chloride, and dichloromethane is 10g:0.8g:45mL; Step A4: Mix the chain extension product of fluorinated polyether polyol and 1,4-dioxane for 30 min, add acryloyl chloride, and reflux and stir at 70 °C for 6 h to obtain fluorinated polyether acrylate; the ratio of chain extension product of fluorinated polyether polyol, 1,4-dioxane and acryloyl chloride is 12 g: 65 mL: 1.1 g.

[0020] Example 2 Fluorinated polyether acrylates are prepared by the following specific steps: Step A1: Add octafluoropentanol and epichlorohydrin to tetrahydrofuran and stir for 33 min. Add potassium hydroxide and reflux at 60 °C for 4.5 h under a nitrogen atmosphere. Rotary evaporate at 40 °C. Adjust the pH to neutral with 20% sodium hydroxide solution. Extract with ethyl acetate and dry with anhydrous sodium sulfate to obtain a fluorinated epoxy compound. The molar ratio of octafluoropentanol to epichlorohydrin is 1:1.5. The ratio of the total mass of octafluoropentanol and epichlorohydrin to the volume of tetrahydrofuran is 1 g:2.3 mL. The amount of sodium hydroxide used is 3% of the mass of octafluoropentanol.

[0021] Step A2: Mix tetrabutylammonium bromide and isopropanol and stir for 13 min. Add the fluorinated epoxy compound, heat to 105℃, reflux and stir at normal pressure for 1.5 h. Add the fluorinated epoxy compound again and continue stirring for 1.5 h. Rotary evaporate at 40℃ to obtain fluorinated polyether polyol. The ratio of isopropanol to fluorinated epoxy compound is 10 mL: 5.5 g, and the amount of tetrabutylammonium bromide is 1.3% of the mass of the fluorinated epoxy compound. The fluorinated epoxy compound is added in two batches, with a mass ratio of 1:1 between the first and second additions. The molecular weight of the fluorinated polyether polyol is 2200. Step A3: Add adipic acid to sulfoxide, add DMF dropwise, and stir at room temperature for 3.5 h to obtain diacyl chloride; mix fluorinated polyether polyol, diacyl chloride, and dichloromethane, heat to 70°C in a nitrogen atmosphere, reflux and stir for 2.5 h, adjust the pH to neutral with 10% sodium hydroxide solution, and rotary evaporate at 40°C to obtain the chain-extended product of fluorinated polyether polyol; the molar ratio of adipic acid, sulfoxide, and DMF is 1:2.8:0.09; the molar ratio of fluorinated polyether polyol, diacyl chloride, and dichloromethane is 11.5 g:0.9 g:50 mL; Step A4: Mix the chain extender of the fluorinated polyether polyol and 1,4-dioxane for 35 min, add methacryloyl chloride, and reflux and stir at 75 °C for 6.5 h to obtain fluorinated polyether acrylate; the ratio of the chain extender of the fluorinated polyether polyol, 1,4-dioxane, and methacryloyl chloride is 13 g: 70 mL: 1.2 g.

[0022] Example 3 Fluorinated polyether acrylates are prepared by the following specific steps: Step A1: Perfluorohexylethanol and epichlorohydrin were added to tetrahydrofuran and stirred for 35 min. Boron trifluoride diethyl ether complex was added, and the mixture was refluxed and stirred at 70 °C for 5 h under a nitrogen atmosphere. The mixture was then rotary evaporated at 40 °C. The pH was adjusted to neutral with a 20% sodium hydroxide solution. The mixture was extracted with ethyl acetate and dried over anhydrous sodium sulfate to obtain a fluorinated epoxy compound. The molar ratio of perfluorohexylethanol to epichlorohydrin was 1:2. The ratio of the total mass of perfluorohexylethanol and epichlorohydrin to the volume of tetrahydrofuran was 1 g: 2.5 mL. The amount of boron trifluoride diethyl ether complex used was 4% of the mass of perfluorohexylethanol.

[0023] Step A2: Mix hexadecyltrimethylammonium chloride and isopropanol and stir for 15 min. Add the fluorinated epoxy compound, heat to 110°C, reflux and stir at normal pressure for 2 h. Add the fluorinated epoxy compound again and continue stirring for 2 h. Rotary evaporate at 40°C to obtain the fluorinated polyether polyol. The ratio of isopropanol to fluorinated epoxy compound is 10 mL: 6 g, and the amount of hexadecyltrimethylammonium chloride is 1.5% of the mass of the fluorinated epoxy compound. The fluorinated epoxy compound is added in two batches, with a mass ratio of 1:1 between the first and second additions. The molecular weight of the fluorinated polyether polyol is 2500. Step A3: Add succinic acid to sulfonium chloride, add DMF dropwise, and stir at room temperature for 4 hours to obtain diacyl chloride; mix fluorinated polyether polyol, diacyl chloride, and dichloromethane, heat to 80°C in a nitrogen atmosphere, reflux and stir for 3 hours, adjust the pH to neutral with 10% sodium hydroxide solution, and rotary evaporate at 40°C to obtain the chain-extended product of fluorinated polyether polyol; the molar ratio of succinic acid, sulfonium chloride, and DMF is 1:3:0.1; the molar ratio of fluorinated polyether polyol, diacyl chloride, and dichloromethane is 13g:1g:55mL; Step A4: Mix the chain extension product of fluorinated polyether polyol and 1,4-dioxane for 40 min, add acryloyl chloride, and reflux and stir at 80 °C for 7 h to obtain fluorinated polyether acrylate; the ratio of chain extension product of fluorinated polyether polyol, 1,4-dioxane and acryloyl chloride is 14 g: 75 mL: 1.3 g.

[0024] Example 4 The compatibilizing monomer is prepared by the following steps: Glycidyl methacrylate, an amino-containing compound, and DMAC were mixed, heated to 40°C, and stirred for 2 hours to obtain a compatibilizing monomer. The ratio of glycidyl methacrylate, amino-containing compound, and DMAC is 15g:9g:35mL; the amino-containing compound is obtained by mixing amino-containing dicarboxynitrile and amino-containing nano-silica in a 1:1 mass ratio. The preparation method of aminodicarboxylon is as follows: 4-nitrophthalonitrile, acetonitrile, and reducing agent are mixed, stirred at room temperature for 2 hours, washed three times with water, rotary evaporated at 45°C, and dried at 105°C for 4 hours to obtain aminodicarboxylon; the ratio of 4-nitrophthalonitrile, acetonitrile, and reducing agent is 9g:20mL:25mL; the reducing agent is a 35% sodium dithionite solution; The preparation method of amino-containing nano-silica is as follows: nano-silica (supplier: Aladdin, item number S490064, 30nm), methanol, water and KH550 are mixed, stirred at room temperature for 1 hour, washed three times with anhydrous ethanol, rotary evaporated at 50℃, and dried at 105℃ for 6 hours to obtain amino-containing nano-silica; the ratio of nano-silica, methanol, water and KH550 is 10g:40mL:10mL:0.25g.

[0025] Example 5 The compatibilizing monomer is prepared by the following steps: Glycidyl methacrylate, an amino-containing compound, and DMAC were mixed, heated to 43°C, and stirred for 2.5 h to obtain a compatibilizing monomer. The ratio of glycidyl methacrylate, amino-containing compound, and DMAC was 16g:9.5g:40mL; the amino-containing compound was obtained by mixing amino-containing dicarboxynitrile and amino-containing nano-silica in a mass ratio of 1:1.2. The preparation method of aminodicarboxynitrile is as follows: 3-nitrophthalonitrile, acetonitrile, and reducing agent are mixed and stirred at room temperature for 2.5 h, washed three times with water, rotary evaporated at 45 °C, and dried at 105 °C for 4 h to obtain aminodicarboxynitrile; the ratio of 3-nitrophthalonitrile, acetonitrile, and reducing agent is 9.5 g: 23 mL: 28 mL; the reducing agent is a 37% sodium dithionite solution; The preparation method of amino-containing nano-silica is as follows: nano-silica (supplier: Aladdin, item number S490064, 30nm), methanol, water and KH540 are mixed and stirred at room temperature for 1.5h. The mixture is washed three times with anhydrous ethanol, rotary evaporated at 50℃, and dried at 105℃ for 6h to obtain amino-containing nano-silica. The ratio of nano-silica, methanol, water and KH540 is 11g:43mL:13mL:0.28g.

[0026] Example 6 The compatibilizing monomer is prepared by the following steps: Glycidyl methacrylate, an amino-containing compound, and DMAC were mixed, heated to 45°C, and stirred for 3 hours to obtain a compatibilizing monomer. The ratio of glycidyl methacrylate, amino-containing compound, and DMAC is 17g:10g:45mL; the amino-containing compound is obtained by mixing amino-containing dicarboxynitrile and amino-containing nano-silica in a mass ratio of 1:1.5. The preparation method of aminodicarboxylon is as follows: 4-nitrophthalonitrile, acetonitrile, and reducing agent are mixed, stirred at room temperature for 3 hours, washed three times with water, rotary evaporated at 45℃, and dried at 105℃ for 4 hours to obtain aminodicarboxylon; the ratio of 4-nitrophthalonitrile, acetonitrile, and reducing agent is 10g:25mL:30mL; the reducing agent is a 40% sodium dithionite solution; The preparation method of amino-containing nano-silica is as follows: nano-silica (supplier: Aladdin, item number S490064, 30nm), methanol, water and KH550 are mixed and stirred at room temperature for 2 hours. The mixture is washed three times with anhydrous ethanol, rotary evaporated at 50℃, and dried at 105℃ for 6 hours to obtain amino-containing nano-silica. The ratio of nano-silica, methanol, water and KH550 is 12g:45mL:15mL:0.3g.

[0027] Example 7 A low-refractive-index optical fiber cladding material composition comprises the following raw materials in parts by weight: 10 parts of fluorinated acrylate, 15 parts of acrylate, 3 parts of acrylic acid, 10 parts of the fluorinated polyether acrylate obtained in Example 1, 2 parts of the compatibilizing monomer obtained in Example 4, 10 parts of solvent, and 0.5 parts of initiator. The fluorinated acrylate is obtained by mixing dodecafluoroheptyl methacrylate, trifluoroethyl methacrylate, and hexafluorobutyl methacrylate in a mass ratio of 1:2:0.6; the acrylate is obtained by mixing methyl methacrylate and butyl acrylate in a mass ratio of 2:1; the solvent is obtained by mixing butyl acetate, ethyl acetate, and methyl acetate in a volume ratio of 2:1:0.5; and the initiator is benzoyl peroxide. The synthesis process of the low refractive index optical fiber cladding material composition includes the following steps: According to the formula, weigh out fluorinated acrylate, acrylate, acrylic acid, fluorinated polyether acrylate obtained in Example 1, compatibilizing monomer obtained in Example 4, and solvent. Stir and mix them for 1 hour in a nitrogen atmosphere at room temperature. Add initiator, stir, heat to 70°C, and continue stirring for 3 hours to obtain a low refractive index optical fiber cladding material composition.

[0028] Example 8 A low-refractive-index optical fiber cladding material composition comprises the following raw materials in parts by weight: 15 parts of fluorinated acrylate, 22 parts of acrylate, 4 parts of acrylic acid, 15 parts of fluorinated polyether acrylate obtained in Example 2, 3 parts of compatibilizing monomer obtained in Example 5, 15 parts of solvent, and 0.8 parts of initiator. The fluorinated acrylate is obtained by mixing dodecafluoroheptyl methacrylate, trifluoroethyl methacrylate, and hexafluorobutyl methacrylate in a mass ratio of 1:2:0.7; the acrylate is obtained by mixing methyl methacrylate and butyl acrylate in a mass ratio of 2:1.3; the solvent is obtained by mixing butyl acetate, ethyl acetate, and methyl acetate in a volume ratio of 2:1:0.8; and the initiator is benzoyl peroxide. The synthesis process of the low refractive index optical fiber cladding material composition includes the following steps: Weigh out the fluorinated acrylate, acrylate, acrylic acid, the fluorinated polyether acrylate obtained in Example 2, the compatibilizing monomer obtained in Example 5, and the solvent according to the formula. Stir and mix them for 1.3 h in a nitrogen atmosphere at room temperature. Add the initiator, stir, heat to 73 °C, and continue stirring for 3.5 h to obtain a low refractive index optical fiber cladding material composition.

[0029] Example 9 A low-refractive-index optical fiber cladding material composition comprises the following raw materials in parts by weight: 20 parts of fluorinated acrylate, 30 parts of acrylate, 5 parts of acrylic acid, 20 parts of fluorinated polyether acrylate obtained in Example 3, 4 parts of compatibilizing monomer obtained in Example 6, 20 parts of solvent, and 1 part of initiator. The fluorinated acrylate is obtained by mixing dodecafluoroheptyl methacrylate, trifluoroethyl methacrylate, and hexafluorobutyl methacrylate in a mass ratio of 1:2:0.8; the acrylate is obtained by mixing methyl methacrylate and butyl acrylate in a mass ratio of 2:1.5; the solvent is obtained by mixing butyl acetate, ethyl acetate, and methyl acetate in a volume ratio of 2:1:1; and the initiator is benzoyl peroxide. The synthesis process of the low refractive index optical fiber cladding material composition includes the following steps: Weigh out the fluorinated acrylate, acrylate, acrylic acid, the fluorinated polyether acrylate obtained in Example 3, the compatibilizing monomer obtained in Example 6, and the solvent according to the formula. Stir and mix them at room temperature in a nitrogen atmosphere for 1.5 h. Add the initiator, stir, heat to 75°C, and continue stirring for 4 h to obtain a low refractive index optical fiber cladding material composition.

[0030] Comparative Example 1 Compared with Example 9, the fluorinated polyether acrylate used was replaced with fluorinated polyether acrylate-1, and the rest was exactly the same as in Example 9, to obtain a low refractive index optical fiber cladding material composition. The preparation method of fluorinated polyether acrylate-1 is as follows: Fluorinated polyether polyol and 1,4-dioxane were mixed and stirred for 40 min, then acryloyl chloride was added, and the mixture was refluxed and stirred at 80 °C for 7 h to obtain fluorinated polyether acrylate-1. The ratio of fluorinated polyether polyol, 1,4-dioxane and acryloyl chloride was 14 g: 75 mL: 1.3 g.

[0031] Comparative Example 2 Compared with Example 9, the aminodicarboxynitrile used in the preparation of the compatibilizing monomer was replaced with 2-amino-4-methylphenol, and the rest was exactly the same as in Example 9, to obtain a low refractive index optical fiber cladding material composition.

[0032] Comparative Example 3 Compared with Example 9, the amino-containing dicarboxynitrile used in the preparation of the compatibilizing monomer was replaced with 4-hydroxybenzonitrile, and the rest was exactly the same as in Example 9, to obtain a low refractive index optical fiber cladding material composition.

[0033] Comparative Example 4 Compared with Example 9, the compatibilizer used was replaced with compatibilizer-1, and nano-silica containing terminal double bonds was added to participate in the polymerization reaction. The mass ratio of compatibilizer-1 to nano-silica containing terminal double bonds was 5.5:1. The compatibilizer monomer-1 is prepared by mixing glycidyl methacrylate, an amino-containing compound, and DMAC, heating to 45°C, and stirring for 3 hours to obtain compatibilizer monomer-1; the ratio of glycidyl methacrylate, an amino-containing compound, and DMAC is 17g:10g:45mL; the amino-containing compound is amino-containing dicarboxynitrile. Preparation method of nano-silica containing terminal double bonds: Nano-silica, methanol, water and KH570 are mixed and stirred at room temperature for 2 hours. The mixture is washed three times with anhydrous ethanol, rotary evaporated at 45°C, and dried at 80°C to obtain nano-silica containing terminal double bonds. The ratio of nano-silica, methanol, water and KH570 is 12g:45mL:15mL:0.3g.

[0034] The optical fiber cladding material composition prepared in this invention was further tested below, and the test results are shown in the figure.

[0035] The fiber cladding composition was coated onto the surface of glass fiber (9µm diameter single-mode fiber) using a 50µm bar coater and cured into a film in a 1kW conveyor-type ultraviolet curing machine (wavelength 365nm, scanning speed 10m / min, curing time 5s) to obtain the fiber cladding (125µm diameter). Refractive index: The refractive index of the fiber cladding at wavelengths of 589 nm and 950 nm was measured using the elliptic polarization method. Tensile strength: The tensile strength of the optical fiber cladding was tested in accordance with GB / T 15972-2021; Hardness: The hardness of the optical fiber cladding was tested according to GB / T 1730-2007; The results are recorded in Table 1.

[0036] Table 1: Test Results According to the data in Table 1, the optical fiber cladding composition of the present invention, after being cured on the surface of the optical fiber to form a cladding, has a low refractive index, high tensile strength and hardness.

[0037] Comparing Example 9 with Comparative Example 1, it can be seen that replacing the fluorinated polyether acrylate with fluorinated polyether acrylate-1 shows that the optical fiber cladding composition of the present invention has a lower refractive index, higher tensile strength and hardness after curing on the optical fiber surface.

[0038] Comparing Example 9 with Comparative Example 2, it can be seen that replacing the aminodicarboxynitrile used in the preparation of the compatibilizing monomer with 2-amino-4-methylphenol shows that the optical fiber cladding composition of the present invention has a lower refractive index and higher tensile strength after curing on the optical fiber surface.

[0039] Comparing Example 9 with Comparative Example 3, it can be seen that replacing the amino-containing dicarboxynitrile used in the preparation of the compatibilizing monomer with 4-hydroxybenzonitrile demonstrates that the optical fiber cladding composition of the present invention has a lower refractive index and higher tensile strength after curing on the optical fiber surface.

[0040] Comparing Example 9 with Comparative Example 4, it can be seen that replacing the compatibility monomer used with compatibility monomer-1 and adding nano-silica containing terminal double bonds to participate in the polymerization reaction shows that the optical fiber cladding composition of the present invention has a lower refractive index, higher tensile strength and hardness after curing on the optical fiber surface.

[0041] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A low-refractive-index optical fiber cladding material composition, characterized in that: The raw materials include the following parts by weight: 10-20 parts of fluorinated acrylate, 15-30 parts of acrylate, 3-5 parts of acrylic acid, 10-20 parts of fluorinated polyether acrylate, 2-4 parts of compatibilizer, 10-20 parts of solvent, and 0.5-1 part of initiator.

2. The low refractive index optical fiber cladding material composition according to claim 1, characterized in that: The fluorinated polyether acrylate is prepared by the following steps: Step A1: Mix small molecule fluorools, epichlorohydrin, and tetrahydrofuran, add a catalyst, and heat and stir in a protective gas atmosphere to obtain a fluorinated epoxy compound. Step A2: Mix the quaternary ammonium salt catalyst and isopropanol, add the fluorinated epoxy compound, heat and reflux with stirring, add the fluorinated epoxy compound, and continue stirring to obtain the fluorinated polyether polyol. Step A3: Add the dicarboxylic acid to thionyl chloride, add DMF dropwise, and stir to obtain diacyl chloride; Fluorinated polyether polyol, diacyl chloride, and dichloromethane were mixed, heated under reflux and stirred in a protective gas atmosphere, and the pH was adjusted to obtain the chain-extended product of fluorinated polyether polyol. Step A4: After mixing and stirring the chain extension product of the fluorinated polyether polyol and 1,4-dioxane, add the acyl chloride containing terminal double bonds, heat and reflux and stir to obtain the fluorinated polyether acrylate.

3. The low refractive index optical fiber cladding material composition according to claim 2, characterized in that: In step A2, the ratio of isopropanol to fluorinated epoxy compound is 10 mL: 5-6 g, and the amount of quaternary ammonium salt catalyst is 1-1.5% of the mass of fluorinated epoxy compound; the fluorinated epoxy compound is added in two parts, with the mass ratio of the first and second additions being 1:

1.

4. The low refractive index optical fiber cladding material composition according to claim 2, characterized in that: In step A3, the molar ratio of the dicarboxylic acid, sulfoxide, and DMF is 1:2.5-3:0.08-0.1; the molar ratio of the fluorinated polyether polyol, diacyl chloride, and dichloromethane is 10-13g:0.8-1g:45-55mL.

5. The low refractive index optical fiber cladding material composition according to claim 1, characterized in that: The compatibilizing monomer is prepared by the following steps: Glycidyl methacrylate, an amino-containing compound, and DMAC were mixed, heated, and stirred to obtain a compatibilizing monomer.

6. The low refractive index optical fiber cladding material composition according to claim 5, characterized in that: The ratio of glycidyl methacrylate, amino-containing compound, and DMAC is 15-17g:9-10g:35-45mL; the amino-containing compound is obtained by mixing amino-containing dicarboxynitrile and amino-containing nano-silica in a mass ratio of 1:1-1.

5.

7. The low refractive index optical fiber cladding material composition according to claim 6, characterized in that: The preparation method of the amino-containing dicarboxylon is as follows: nitrile-containing phthalonitrile, acetonitrile, and a reducing agent are mixed and stirred at room temperature to obtain amino-containing dicarboxylon; the preparation method of the amino-containing nano-silica is as follows: nano-silica, methanol, water, and an amino-containing silane coupling agent are mixed and stirred at room temperature to obtain amino-containing nano-silica.

8. The low refractive index optical fiber cladding material composition according to claim 7, characterized in that: The nitrile-containing phthalonitrile is 4-nitrophthalonitrile or 3-nitrophthalonitrile.

9. A synthesis process for the low refractive index optical fiber cladding material composition according to any one of claims 1-8, characterized in that: Includes the following steps: Weigh out fluorinated acrylate, acrylate, acrylic acid, fluorinated polyether acrylate, compatibilizer and solvent according to the formula, stir and mix them in a protective gas atmosphere at room temperature, add initiator, stir and heat, continue stirring to obtain a low refractive index optical fiber cladding material composition.

10. The application of a low-refractive-index optical fiber cladding material composition according to any one of claims 1-8, characterized in that: The composition is used to prepare optical fiber cladding.

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