A resin for a flame-retardant optical fiber reinforcing core and a method for producing the same

Abstract

The application discloses a kind of resin for flame-retardant optical fiber reinforcing core and preparation method thereof, it is related to epoxy resin technical field.The resin for flame-retardant optical fiber reinforcing core includes the following mass parts components: 80~90 parts bisphenol A epoxy resin, 2~4 parts trimethylolpropane triglycidyl ether, 6~8 parts 4,4'-diphenyl bisphenol diglycidyl ether, 5~7 parts amino boron nitride, 15~18 parts toughening curing agent, 25~35 parts acid anhydride curing agent, 0.2~1 parts accelerator.On the basis of guaranteeing low shrinkage, the mechanical properties, flame-retardant performance of resin for flame-retardant optical fiber reinforcing core are effectively improved.

Description

Technical Field

[0001] This invention relates to the field of epoxy resin technology, specifically to a flame-retardant resin for optical fiber reinforcing cores and its preparation method. Background Technology

[0002] In the field of optical fiber, the fiber reinforcement core is a material formed by combining fiber materials and resin. It is a key component that ensures the mechanical strength and weather resistance of optical fibers. Commonly used resins for fiber reinforcement cores include epoxy resin and unsaturated polyester resin. Compared with unsaturated polyester resin, epoxy resin has disadvantages such as poor weather resistance and high shrinkage rate, which affects the long-term stability of optical fibers and optical signal transmission. Epoxy resin contains benzene rings, has good weather resistance, and low shrinkage rate, making it more suitable for use in optical fibers.

[0003] Epoxy resins, due to their benzene ring content, exhibit high rigidity, high brittleness, and poor toughness. Existing technologies typically introduce toughening agents, usually long-chain substances, to improve their toughness. However, the introduction of these agents increases curing shrinkage, leading to a deterioration in fiber optic transmission performance. On the other hand, to improve safety, flame retardants are generally introduced to effectively enhance the flame retardancy of epoxy resins. However, the introduction of flame retardants presents compatibility issues, resulting in poor interfacial uniformity and reduced curing crosslinking, thereby reducing mechanical properties such as impact resistance and affecting fiber optic transmission performance.

[0004] In summary, the preparation of a flame-retardant resin for optical fiber reinforcing cores and its preparation method are of great significance in order to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide a flame-retardant resin for optical fiber reinforcing cores and a method for preparing the same, in order to solve the problems mentioned in the background art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] A method for preparing a flame-retardant resin for an optical fiber reinforcing core includes the following steps:

[0008] Step 1: (1) Disperse hydrotalcite and cyclodextrin in deionized water using ultrasonication; add potassium hydroxide and stir evenly at room temperature; add methanol and react at 60-65°C for 6-12 hours; add aminosilane coupling agent and stir for 6-12 hours; let stand at room temperature, centrifuge, wash, and dry to obtain aminocyclodextrin MOF; (2) Add aminocyclodextrin MOF and p-methylbenzenesulfonyl isocyanate to dichloromethane and stir at room temperature for 12-24 hours under nitrogen atmosphere to obtain toughening curing agent;

[0009] Step 2: Mix bisphenol A epoxy resin, trimethylolpropane triglycidyl ether, 4,4'-biphenyl bisphenol diglycidyl ether, aminated boron nitride, toughening curing agent, acid anhydride curing agent, and accelerator evenly to obtain flame-retardant fiber reinforcing core resin.

[0010] In a more optimized manner, the resin for the flame-retardant optical fiber reinforcing core comprises the following components in parts by weight: 80-90 parts bisphenol A epoxy resin, 2-4 parts trimethylolpropane triglycidyl ether, 6-8 parts 4,4'-biphenyl bisphenol diglycidyl ether, 5-7 parts aminated boron nitride, 15-18 parts toughening curing agent, 25-35 parts acid anhydride curing agent, and 0.2-1 part accelerator.

[0011] In a more optimized manner, the mass ratio of aminocyclodextrin MOF to p-toluenesulfonyl isocyanate in the raw materials of the toughening curing agent is 10:(0.3~0.5).

[0012] The aminocyclodextrin MOF comprises the following raw materials in parts by weight: 10 parts hydrotalcite, 40-50 parts deionized water, 12-18 parts cyclodextrin, 4.8-6.7 parts potassium hydroxide, 20-30 parts methanol, and 1.5-2.5 parts aminosilane coupling agent.

[0013] A more optimized method for preparing the aminosilane coupling agent is as follows: acrylate-polyethylene glycol-amino and 3-mercaptopropyltriethoxysilane in a molar ratio of 1:1 are sequentially added to tetrahydrofuran, followed by the addition of photoinitiator AIBN. The light intensity is set to 100-120 mW / cm² at room temperature. 2 The reaction was carried out under ultraviolet light for 2-4 hours, followed by post-treatment to obtain an aminosilane coupling agent.

[0014] In a more optimized manner, the preparation method of the aminated boron nitride is as follows: (1) Add boron nitride and phenylboronic acid to deionized water, intermittently wet mill under nitrogen for 6-8 hours, and dry to obtain pretreated boron nitride; (2) Ultrasonically disperse the pretreated boron nitride in 70-80% ethanol aqueous solution, add aminosilane coupling agent, stir at 60-65℃ for 4-6 hours, filter, wash and dry to obtain aminated boron nitride.

[0015] More optimally, in the raw materials for pretreated boron nitride, the mass ratio of boron nitride to phenylboronic acid is 1:(4~5); in the raw materials for amino-modified boron nitride, the mass ratio of pretreated boron nitride to aminosilane coupling agent is 1:0.2~0.3.

[0016] More preferably, the anhydride curing agent includes one or more of tetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, and hexahydrophthalic anhydride; the accelerator includes one or two of benzyldimethylamine and 2-ethyl-4-methylimidazole.

[0017] In a more optimized manner, the curing process of the resin for the flame-retardant optical fiber reinforcing core is as follows: curing at 80~100℃ for 1~2 hours; curing at 110~120℃ for 0.5~1 hours; and curing at 130~140℃ for 2~3 hours.

[0018] A method for preparing a flame-retardant resin for fiber optic reinforcing cores.

[0019] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: The present application uses bisphenol A epoxy resin as the main component and trimethylolpropane triglycidyl ether and 4,4'-biphenyl bisphenol diglycidyl ether as auxiliary components as the base epoxy resin; and uses a toughening curing agent formed by cyclodextrin, an amino boron nitride, and an anhydride curing agent. The three are used in combination to grade and cure the base epoxy resin. In this way, while ensuring a low curing shrinkage rate, the flame retardancy and impact resistance of the resin used for flame-retardant optical fiber reinforcing core are effectively improved.

[0020] This invention utilizes hydrotalcite as a base, with cyclodextrin MOFs loaded onto its surface, followed by the loading of an aminosilane coupling agent and the use of methylbenzenesulfonyl isocyanate to form a latent toughening curing agent. Regarding curing performance, it releases active groups in stages during heating, reducing curing stress; effectively improving impact strength and reducing curing shrinkage; and its sulfonylurea moiety, compared to other latent curing agents, allows for complete crosslinking at 140℃ without reaching 150℃, reducing energy consumption and thermal stress while ensuring performance. For toughening, the layered structure of hydrotalcite and the cavities in cyclodextrin create nanopores that effectively buffer or absorb impact energy under external forces, inhibiting cracking and improving toughness; simultaneously, the aminosilane coupling agent contains flexible segments, reducing the rigidity of the crosslinked network and effectively toughening the material. In addition, it also contains flame retardant properties. Hydrotalcite is an excellent flame retardant material, and the metal compounds it contains can promote the formation of a dense carbon layer in the subsequently loaded cyclodextrin MOF, which blocks heat transfer and produces flame retardancy. The other introduced amino boron nitride is interspersed in the epoxy resin to produce a flame-retardant "mud-tile structure", which synergistically enhances the flame retardancy.

[0021] The introduction of trimethylolpropane triglycidyl ether and 4,4'-biphenyl bisphenol diglycidyl ether provides auxiliary agents. Trimethylolpropane triglycidyl ether can act as a reactive diluent to ensure the resin's impregnation process of the fiber reinforcement layer. Meanwhile, 4,4'-biphenyl bisphenol diglycidyl ether can reduce the free volume of the molecular chain and inhibit shrinkage.

[0022] The combination of toughening curing agent, amino boron nitride, and anhydride curing agent enables staged curing, effectively ensuring curing uniformity, reducing curing stress, and minimizing curing shrinkage. Specifically, the amino groups in amino boron nitride can pre-cur at 80-100℃ to form a preliminary network. Due to the excellent thermal conductivity of amino boron nitride and 4,4'-biphenyl bisphenol diglycidyl ether contained in this preliminary network, they can act on the toughening curing agent. At 110-120℃, some sulfonylurea bonds decompose, and then at 130-140℃, they completely decompose to generate active groups, which act uniformly within the epoxy resin. Together with the anhydride curing agent, they form a uniform cross-linked network, effectively ensuring impact resistance and low shrinkage. Detailed Implementation

[0023] 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.

[0024] It should be noted that the following quantities are by weight. There are no special restrictions on the manufacturers of the raw materials involved in this invention. Exemplary examples include: the average molecular weight of acrylate-polyethylene glycol-amino is 1K; the CAS number of 3-mercaptopropyltriethoxysilane is 14814-09-6; the product number of boron nitride is Q-0249641, brand Qiyue Biotechnology; the CAS number of phenylboronic acid is 98-80-6; the hydrotalcite is aluminum magnesium hydrotalcite, brand Quhuayan; the CAS number of γ-cyclodextrin is 17465-86-0; the CAS number of p-methylbenzenesulfonyl isocyanate is 4083-64-1; the model of bisphenol A epoxy resin is E-51; the CAS number of trimethylolpropane triglycidyl ether is 30499-70-8; the CAS number of biphenyl bisphenol diglycidyl ether is 2461-46-3; and other raw materials are all commercially available.

[0025] Example 1: A method for preparing a flame-retardant resin for an optical fiber reinforcing core, comprising the following steps:

[0026] Preparation: Preparation of aminosilane coupling agent: Acrylate-polyethylene glycol-amino and 3-mercaptopropyltriethoxysilane in a molar ratio of 1:1 were sequentially added to tetrahydrofuran, and photoinitiator AIBN was added. The light intensity was set to 120 mW / cm² at room temperature. 2 The reaction was carried out under ultraviolet light for 2 hours, followed by post-treatment to obtain an aminosilane coupling agent.

[0027] The preparation method of aminated boron nitride is as follows: (1) Add boron nitride and phenylboronic acid in a mass ratio of 1:4 to deionized water, intermittently wet mill under nitrogen for 6 hours, and dry to obtain pretreated boron nitride; (2) Disperse 10 parts of pretreated boron nitride ultrasonically in 80% ethanol aqueous solution, add 0.25 parts of aminosilane coupling agent, stir at 60°C for 6 hours, filter, wash and dry to obtain aminated boron nitride;

[0028] Step 1: (1) Disperse 10 parts of hydrotalcite and 16 parts of γ-cyclodextrin in 50 parts of deionized water using ultrasonication; add 6 parts of potassium hydroxide and stir evenly at room temperature; add 30 parts of methanol and react at 60°C for 12 hours; add 2 parts of aminosilane coupling agent and stir for 12 hours; let stand at room temperature, centrifuge, wash, and dry to obtain aminocyclodextrin MOF; (2) Add aminocyclodextrin MOF and p-methylbenzenesulfonyl isocyanate in a mass ratio of 10:0.4 to dichloromethane and stir at room temperature for 24 hours under a nitrogen atmosphere to obtain toughening curing agent;

[0029] Step 2: Mix 90 parts of bisphenol A epoxy resin E-51, 3 parts of trimethylolpropane triglycidyl ether, 7 parts of 4,4'-biphenyl bisphenol diglycidyl ether, 6 parts of aminated boron nitride, 16 parts of toughening curing agent, 30 parts of tetrahydrophthalic anhydride, and 0.5 parts of 2-ethyl-4-methylimidazole evenly to obtain a flame-retardant fiber optic reinforcing core resin.

[0030] Example 2: A method for preparing a flame-retardant resin for an optical fiber reinforcing core, comprising the following steps:

[0031] Preparation: Preparation of aminosilane coupling agent: Acrylate-polyethylene glycol-amino and 3-mercaptopropyltriethoxysilane in a molar ratio of 1:1 were sequentially added to tetrahydrofuran, and photoinitiator AIBN was added. The light intensity was set to 120 mW / cm² at room temperature. 2 The reaction was carried out under ultraviolet light for 2 hours, followed by post-treatment to obtain an aminosilane coupling agent.

[0032] The preparation method of aminated boron nitride is as follows: (1) Add boron nitride and phenylboronic acid in a mass ratio of 1:4 to deionized water, intermittently wet mill under nitrogen for 6 hours, and dry to obtain pretreated boron nitride; (2) Disperse 10 parts of pretreated boron nitride ultrasonically in 80% ethanol aqueous solution, add 0.25 parts of aminosilane coupling agent, stir at 60°C for 6 hours, filter, wash and dry to obtain aminated boron nitride;

[0033] Step 1: (1) Disperse 10 parts of hydrotalcite and 16 parts of γ-cyclodextrin in 50 parts of deionized water using ultrasonication; add 6 parts of potassium hydroxide and stir evenly at room temperature; add 30 parts of methanol and react at 60°C for 12 hours; add 2 parts of aminosilane coupling agent and stir for 12 hours; let stand at room temperature, centrifuge, wash, and dry to obtain aminocyclodextrin MOF; (2) Add aminocyclodextrin MOF and p-methylbenzenesulfonyl isocyanate in a mass ratio of 10:0.4 to dichloromethane and stir at room temperature for 24 hours under a nitrogen atmosphere to obtain toughening curing agent;

[0034] Step 2: Mix 80 parts of bisphenol A epoxy resin E-51, 2 parts of trimethylolpropane triglycidyl ether, 6 parts of 4,4'-biphenyl bisphenol diglycidyl ether, 5 parts of aminated boron nitride, 15 parts of toughening curing agent, 25 parts of tetrahydrophthalic anhydride, and 0.5 parts of 2-ethyl-4-methylimidazole evenly to obtain a flame-retardant fiber optic reinforcing core resin.

[0035] Example 3: A method for preparing a flame-retardant resin for an optical fiber reinforcing core, comprising the following steps:

[0036] Preparation: Preparation of aminosilane coupling agent: Acrylate-polyethylene glycol-amino and 3-mercaptopropyltriethoxysilane in a molar ratio of 1:1 were sequentially added to tetrahydrofuran, and photoinitiator AIBN was added. The light intensity was set to 120 mW / cm² at room temperature. 2 The reaction was carried out under ultraviolet light for 2 hours, followed by post-treatment to obtain an aminosilane coupling agent.

[0037] The preparation method of aminated boron nitride is as follows: (1) Add boron nitride and phenylboronic acid in a mass ratio of 1:4 to deionized water, intermittently wet mill under nitrogen for 6 hours, and dry to obtain pretreated boron nitride; (2) Disperse 10 parts of pretreated boron nitride ultrasonically in 80% ethanol aqueous solution, add 0.25 parts of aminosilane coupling agent, stir at 60°C for 6 hours, filter, wash and dry to obtain aminated boron nitride;

[0038] Step 1: (1) Disperse 10 parts of hydrotalcite and 16 parts of γ-cyclodextrin in 50 parts of deionized water using ultrasonication; add 6 parts of potassium hydroxide and stir evenly at room temperature; add 30 parts of methanol and react at 60°C for 12 hours; add 2 parts of aminosilane coupling agent and stir for 12 hours; let stand at room temperature, centrifuge, wash, and dry to obtain aminocyclodextrin MOF; (2) Add aminocyclodextrin MOF and p-methylbenzenesulfonyl isocyanate in a mass ratio of 10:0.4 to dichloromethane and stir at room temperature for 24 hours under a nitrogen atmosphere to obtain toughening curing agent;

[0039] Step 2: Mix 90 parts of bisphenol A epoxy resin E-51, 4 parts of trimethylolpropane triglycidyl ether, 8 parts of 4,4'-biphenyl bisphenol diglycidyl ether, 7 parts of aminated boron nitride, 18 parts of toughening curing agent, 35 parts of tetrahydrophthalic anhydride, and 0.5 parts of 2-ethyl-4-methylimidazole evenly to obtain a flame-retardant fiber optic reinforcing core resin.

[0040] Comparative Example 1: The aminosilane coupling agent was replaced with KH602, and the rest was the same as in Example 1; the details are as follows:

[0041] Preparatory steps: The preparation method of aminated boron nitride is as follows: (1) Add boron nitride and phenylboronic acid in a mass ratio of 1:4 to deionized water, intermittently wet grind under nitrogen for 6 hours, and dry to obtain pretreated boron nitride; (2) Disperse 10 parts of pretreated boron nitride ultrasonically in 80% ethanol aqueous solution, add 0.25 parts of aminosilane coupling agent KH602, stir at 60℃ for 6 hours, filter, wash and dry to obtain aminated boron nitride;

[0042] Step 1: (1) Disperse 10 parts of hydrotalcite and 16 parts of γ-cyclodextrin in 50 parts of deionized water using ultrasonication; add 6 parts of potassium hydroxide and stir evenly at room temperature; add 30 parts of methanol and react at 60°C for 12 hours; add 2 parts of aminosilane coupling agent KH602 and stir for 12 hours, let stand at room temperature, centrifuge, wash, and dry to obtain aminocyclodextrin MOF; (2) Add aminocyclodextrin MOF and p-methylbenzenesulfonyl isocyanate in a mass ratio of 10:0.4 to dichloromethane and stir at room temperature for 24 hours under a nitrogen atmosphere to obtain toughening curing agent;

[0043] Step 2: Mix 90 parts of bisphenol A epoxy resin E-51, 3 parts of trimethylolpropane triglycidyl ether, 7 parts of 4,4'-biphenyl bisphenol diglycidyl ether, 6 parts of aminated boron nitride, 16 parts of toughening curing agent, 30 parts of tetrahydrophthalic anhydride, and 0.5 parts of 2-ethyl-4-methylimidazole evenly to obtain a flame-retardant fiber optic reinforcing core resin.

[0044] Comparative Example 2: Boron nitride amide was not introduced, and a single toughening and curing agent was used; the rest was the same as in Example 1; details are as follows:

[0045] Preparation: Preparation of aminosilane coupling agent: Acrylate-polyethylene glycol-amino and 3-mercaptopropyltriethoxysilane in a molar ratio of 1:1 were sequentially added to tetrahydrofuran, and photoinitiator AIBN was added. The light intensity was set to 120 mW / cm² at room temperature. 2 The reaction was carried out under ultraviolet light for 2 hours, followed by post-treatment to obtain an aminosilane coupling agent.

[0046] Step 1: (1) Disperse 10 parts of hydrotalcite and 16 parts of γ-cyclodextrin in 50 parts of deionized water using ultrasonication; add 6 parts of potassium hydroxide and stir evenly at room temperature; add 30 parts of methanol and react at 60°C for 12 hours; add 2 parts of aminosilane coupling agent and stir for 12 hours; let stand at room temperature, centrifuge, wash, and dry to obtain aminocyclodextrin MOF; (2) Add aminocyclodextrin MOF and p-methylbenzenesulfonyl isocyanate in a mass ratio of 10:0.4 to dichloromethane and stir at room temperature for 24 hours under a nitrogen atmosphere to obtain toughening curing agent;

[0047] Step 2: Mix 90 parts of bisphenol A epoxy resin E-51, 3 parts of trimethylolpropane triglycidyl ether, 7 parts of 4,4'-biphenyl bisphenol diglycidyl ether, 22 parts of toughening curing agent, 30 parts of tetrahydrophthalic anhydride, and 0.5 parts of 2-ethyl-4-methylimidazole evenly to obtain a flame-retardant fiber optic reinforcing core resin.

[0048] Comparative Example 3: Directly introduced amino-modified cyclodextrin MOF, otherwise the same as in Example 1; details are as follows:

[0049] Preparation: Preparation of aminosilane coupling agent: Acrylate-polyethylene glycol-amino and 3-mercaptopropyltriethoxysilane in a molar ratio of 1:1 were sequentially added to tetrahydrofuran, and photoinitiator AIBN was added. The light intensity was set to 120 mW / cm² at room temperature. 2 The reaction was carried out under ultraviolet light for 2 hours, followed by post-treatment to obtain an aminosilane coupling agent.

[0050] The preparation method of aminated boron nitride is as follows: (1) Add boron nitride and phenylboronic acid in a mass ratio of 1:4 to deionized water, intermittently wet mill under nitrogen for 6 hours, and dry to obtain pretreated boron nitride; (2) Disperse 10 parts of pretreated boron nitride ultrasonically in 80% ethanol aqueous solution, add 0.25 parts of aminosilane coupling agent, stir at 60°C for 6 hours, filter, wash and dry to obtain aminated boron nitride;

[0051] Step 1: (1) Disperse 10 parts of hydrotalcite and 16 parts of γ-cyclodextrin in 50 parts of deionized water by ultrasonication; add 6 parts of potassium hydroxide and stir evenly at room temperature; add 30 parts of methanol and react at 60°C for 12 hours; add 2 parts of aminosilane coupling agent, stir for 12 hours, let stand at room temperature, centrifuge, wash and dry to obtain amino-modified cyclodextrin MOF.

[0052] Step 2: Mix 90 parts of bisphenol A epoxy resin E-51, 3 parts of trimethylolpropane triglycidyl ether, 7 parts of 4,4'-biphenyl bisphenol diglycidyl ether, 6 parts of aminated boron nitride, 16 parts of aminated cyclodextrin MOF, 30 parts of tetrahydrophthalic anhydride, and 0.5 parts of 2-ethyl-4-methylimidazolium evenly to obtain a flame-retardant fiber optic reinforcing core resin.

[0053] Comparative Example 4: The toughening curing agent and tetrahydrophthalic anhydride components were interchanged, and the rest was the same as in Example 1; the specific details are as follows: Preparatory work: Preparation of aminosilane coupling agent: acrylate-polyethylene glycol-amino and 3-mercaptopropyltriethoxysilane in a molar ratio of 1:1 were added sequentially to tetrahydrofuran, and photoinitiator AIBN was added. At room temperature, the light intensity was set to 120 mW / cm. 2 The reaction was carried out under ultraviolet light for 2 hours, followed by post-treatment to obtain an aminosilane coupling agent.

[0054] The preparation method of aminated boron nitride is as follows: (1) Add boron nitride and phenylboronic acid in a mass ratio of 1:4 to deionized water, intermittently wet mill under nitrogen for 6 hours, and dry to obtain pretreated boron nitride; (2) Disperse 10 parts of pretreated boron nitride ultrasonically in 80% ethanol aqueous solution, add 0.25 parts of aminosilane coupling agent, stir at 60°C for 6 hours, filter, wash and dry to obtain aminated boron nitride;

[0055] Step 1: (1) Disperse 10 parts of hydrotalcite and 16 parts of γ-cyclodextrin in 50 parts of deionized water using ultrasonication; add 6 parts of potassium hydroxide and stir evenly at room temperature; add 30 parts of methanol and react at 60°C for 12 hours; add 2 parts of aminosilane coupling agent and stir for 12 hours; let stand at room temperature, centrifuge, wash, and dry to obtain aminocyclodextrin MOF; (2) Add aminocyclodextrin MOF and p-methylbenzenesulfonyl isocyanate in a mass ratio of 10:0.4 to dichloromethane and stir at room temperature for 24 hours under a nitrogen atmosphere to obtain toughening curing agent;

[0056] Step 2: Mix 90 parts of bisphenol A epoxy resin E-51, 3 parts of trimethylolpropane triglycidyl ether, 7 parts of 4,4'-biphenyl bisphenol diglycidyl ether, 6 parts of aminated boron nitride, 30 parts of toughening curing agent, 16 parts of tetrahydrophthalic anhydride, and 0.5 parts of 2-ethyl-4-methylimidazole evenly to obtain a flame-retardant fiber optic reinforcing core resin.

[0057] Performance Test 1: The flame-retardant fiber reinforcing core resin prepared in the examples and comparative examples was cured at 100°C for 1.5 hours; at 110~120°C for 1 hour; and at 130~140°C for 2.5 hours to form a material. The impact strength, shrinkage rate, and flame retardancy were then tested. The impact strength was measured using an 80×10×4mm... 3 The samples were tested for unnotched impact strength using a pendulum impact testing machine with a span of 62 mm and an impact energy of 5 J at room temperature. Shrinkage was measured using the density method (volume shrinkage rate). Flame retardancy was tested using a limiting oxygen index (LOI) tester. The obtained data are shown in the table below.

[0058]

[0059] Conclusion: The data in the table above show that, while ensuring low shrinkage, the mechanical and flame-retardant properties of the resin used for the reinforcing core of flame-retardant optical fibers were effectively improved. In Comparative Example 1, replacing the aminosilane coupling agent with KH602 resulted in a decrease in impact strength and other properties due to the lack of flexible chain segments to synergistically absorb impact energy. In Comparative Example 2, the absence of amino boron nitride and the use of a single toughening curing agent led to a decrease in curing uniformity and related properties. In Comparative Example 3, the direct introduction of amino cyclodextrin MOF increased curing stress and decreased curing uniformity. In Comparative Example 4, the substitution of the toughening curing agent and tetrahydrophthalic anhydride resulted in insufficient curing, stress concentration, and a decrease in performance.

[0060] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a flame-retardant resin for an optical fiber reinforcing core, characterized in that: Includes the following steps: Step 1: (1) Disperse hydrotalcite and cyclodextrin in deionized water using ultrasonication; add potassium hydroxide and stir evenly at room temperature; add methanol and react at 60-65°C for 6-12 hours; add aminosilane coupling agent and stir for 6-12 hours; let stand at room temperature, centrifuge, wash, and dry to obtain aminocyclodextrin MOF; (2) Add aminocyclodextrin MOF and p-methylbenzenesulfonyl isocyanate to dichloromethane and stir at room temperature for 12-24 hours under nitrogen atmosphere to obtain toughening curing agent; Step 2: Mix bisphenol A epoxy resin, trimethylolpropane triglycidyl ether, 4,4'-biphenyl bisphenol diglycidyl ether, aminated boron nitride, toughening curing agent, acid anhydride curing agent, and accelerator evenly to obtain flame-retardant fiber reinforcing core resin. The flame-retardant fiber reinforcing core resin comprises the following components by weight: 80-90 parts bisphenol A epoxy resin, 2-4 parts trimethylolpropane triglycidyl ether, 6-8 parts 4,4'-biphenyl bisphenol diglycidyl ether, 5-7 parts aminated boron nitride, 15-18 parts toughening curing agent, 25-35 parts acid anhydride curing agent, and 0.2-1 part accelerator. The preparation method of the aminosilane coupling agent is as follows: acrylate-polyethylene glycol-amino and 3-mercaptopropyltriethoxysilane in a molar ratio of 1:1 are sequentially added to tetrahydrofuran, and photoinitiator AIBN is added. At room temperature, the light intensity is set to 100~120 mW / cm². 2 The reaction was carried out under ultraviolet light for 2-4 hours, followed by post-treatment to obtain an aminosilane coupling agent. The preparation method of the aminated boron nitride is as follows: (1) Add boron nitride and phenylboronic acid to deionized water, intermittently wet grind under nitrogen for 6-8 hours, and dry to obtain pretreated boron nitride; (2) Ultrasonically disperse the pretreated boron nitride in 70-80% ethanol aqueous solution, add aminosilane coupling agent, stir at 60-65℃ for 4-6 hours, filter, wash and dry to obtain aminated boron nitride.

2. The method for preparing a flame-retardant resin for an optical fiber reinforcing core according to claim 1, characterized in that: In the raw materials of the toughening and curing agent, the mass ratio of aminocyclodextrin MOF to p-methylbenzenesulfonyl isocyanate is 10:(0.3~0.5). The aminocyclodextrin MOF comprises the following raw materials in parts by weight: 10 parts hydrotalcite, 40-50 parts deionized water, 12-18 parts cyclodextrin, 4.8-6.7 parts potassium hydroxide, 20-30 parts methanol, and 1.5-2.5 parts aminosilane coupling agent.

3. The method for preparing a flame-retardant resin for an optical fiber reinforcing core according to claim 1, characterized in that: In the raw materials for pretreated boron nitride, the mass ratio of boron nitride to phenylboronic acid is 1:(4~5); in the raw materials for amino-modified boron nitride, the mass ratio of pretreated boron nitride to aminosilane coupling agent is 1:0.2~0.

3.

4. The method for preparing a flame-retardant resin for an optical fiber reinforcing core according to claim 1, characterized in that: The anhydride curing agent includes one or more of tetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, and hexahydrophthalic anhydride; the accelerator includes one or two of benzyldimethylamine and 2-ethyl-4-methylimidazole.

5. The method for preparing a flame-retardant resin for an optical fiber reinforcing core according to claim 1, characterized in that: The curing process of the resin for the flame-retardant optical fiber reinforcing core is as follows: curing at 80~100℃ for 1~2 hours; curing at 110~120℃ for 0.5~1 hours; and curing at 130~140℃ for 2~3 hours.

6. The flame-retardant fiber optic reinforcing core resin prepared by the method for preparing a flame-retardant fiber optic reinforcing core according to any one of claims 1 to 5.

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