A method for preparing a light-cured coating for side-emitting optical fibers

Abstract

The application relates to the technical field of optical fiber coating material preparation, and discloses a preparation method of light-cured coating for side light-emitting optical fiber; a solvent-free ultraviolet light-cured coating is prepared, the coating is coated on the surface of an optical fiber mandrel by adopting a single-layer single-time coating process and is solidified, and only a single-layer functional coating is arranged after molding; the coating takes a multifunctional fluorine-containing acrylate resin as a film-forming matrix, is doped with inorganic nano scattering particles and is dispersedly modified by cooperating with a fluorine-modified polymer dispersant, multifunctional fluorine-containing resin is compounded with nano particles in a specific proportion, the refractive index of the coating after solidification can be precisely and stably controlled in the interval of 1.39-1.42, the refractive index of the coating is perfectly matched with the refractive index of a common optical fiber core layer, light leakage is uniform, the problems of uneven light-emitting brightness and irregular light spots of traditional optical fibers are completely solved, and the side light-emitting effect is soft and uniform.

Description

Technical Field

[0001] This invention relates to the field of optical fiber coating material preparation technology, specifically a method for preparing a photocurable coating for side-emitting optical fibers. Background Technology

[0002] Side-emitting optical fiber is a special type of optical fiber that can uniformly scatter a portion of the light transmitted inside the fiber from its sidewalls. With its advantages of high flexibility, no light spots, soft light, safety, low voltage, and bend resistance, it is widely used in landscape lighting, interior decoration, intelligent backlighting, and minimally invasive medical lighting. The luminous performance of side-emitting optical fiber depends primarily on the optical parameters and structural design of its surface coating. The refractive index, light transmission uniformity, and particle dispersion of the coating directly determine the uniformity of side-emitting light, luminous efficiency, and lifespan of the fiber.

[0003] Currently, most mainstream side-emitting optical fibers on the market adopt a double-layer coating structure, with an inner low-refractive-index light-transmitting layer and an outer scattering light-emitting layer. This process is complex, inefficient, and costly. Furthermore, existing light-emitting coatings generally suffer from significant technical defects: First, conventional coating matrix resins have poor compatibility with inorganic scattering particles; nano-silica, titanium dioxide, and other particles are prone to aggregation and sedimentation, leading to uneven light transmission in the coating, bright and dark spots in the fiber emitting light, and light interruption. Second, common dispersants are mostly hydrocarbon systems, which have extremely poor compatibility with low-refractive-index fluorinated resin matrices, causing coating fogging, refractive index shifts, and making precise control of optical parameters impossible. Third, traditional coatings have a large refractive index fluctuation range, making it difficult to stably match the refractive index of the fiber core, resulting in uneven light leakage and poor side-emitting effects. Fourth, the double-layer coating process is cumbersome, coating adhesion is poor, and long-term use easily leads to peeling, flaking, and yellowing, with insufficient weather resistance and stability.

[0004] In view of the shortcomings of existing technologies, such as complex processes, particle agglomeration, poor optical stability, uneven light emission, and high cost, there is an urgent need to develop a method for preparing a special photocurable coating for side-emitting optical fibers that is compatible with single-layer coating processes, has a precisely controllable refractive index, uniform particle dispersion, and excellent compatibility. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a photocurable coating for side-emitting optical fibers, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a photocurable coating for side-emitting optical fibers, comprising the following steps: A solvent-free UV-curable coating was prepared by applying the coating to the surface of an optical fiber core rod using a single-layer, single-coat process and then curing it. After curing, only a single functional coating layer is formed. The coating uses a multifunctional fluorinated acrylate resin as the film-forming matrix, doped with inorganic nano-scattering particles, and modified by a fluorinated polymeric dispersant. After curing, the refractive index of the coating is stably controlled between 1.39 and 1.42. The fluorinated polymeric dispersant has both fluorine-compatible segments and inorganic particle anchoring groups, which enables the inorganic nanoparticles to be uniformly dispersed in the fluorinated resin system without agglomeration or sedimentation.

[0007] Preferably, the raw material components of the coating, by mass percentage, include: 87%–91% multifunctional fluorinated acrylate resin, 4%–8% inorganic nanoparticles, 2%–4% ultraviolet photoinitiator, and 0.2%–1% auxiliary additives; the amount of fluorinated modified polymeric dispersant added is 5%–10% of the mass of inorganic nanoparticles; the total mass percentage of each component is 100%.

[0008] Preferably, the multifunctional fluorinated acrylate resin is any one or more of trifunctional fluorinated acrylate resin, tetrafunctional fluorinated acrylate resin, and hexafunctional fluorinated acrylate resin, compounded in any proportion.

[0009] Preferably, the inorganic nanoparticles are any single type of nano-silica, nano-titanium dioxide, or nano-zirconium dioxide, with a particle size of 20–80 nm.

[0010] Preferably, the fluorinated polymeric dispersant is a fluorinated anchoring polymeric dispersant that is fully compatible with multifunctional fluorinated acrylate resins and can surface-coat and modify inorganic nanoparticles to inhibit particle aggregation.

[0011] Preferably, the process includes the following steps: S1. Pre-dispersion treatment: Disperse the fluorinated polymeric dispersant in part of the multifunctional fluorinated acrylate resin and stir at low speed for 3-5 min to form a uniform premix; add the measured amount of inorganic nanoparticles, premix at low speed for 10 min, and then disperse at high speed of 3000-4000 r / min for 20-30 min to initially break up the particle agglomerates. S2. Fine grinding and homogenization: The mixture obtained in step S1 is subjected to wet sand milling for 30 to 40 minutes, and the particle size D50 is controlled to be ≤50nm to achieve uniform dispersion of inorganic nanoparticles throughout the entire domain. S3. System compounding and mixing: Under normal temperature and light-protected environment, add the remaining multifunctional fluorinated acrylate resin, ultraviolet photoinitiator and auxiliary additives to the ground and homogenized material, stir at low speed of 800-1200r / min for 15-20min, and after thorough mixing, filter to remove impurities to obtain the UV-curable coating stock solution. S4. Single-layer coating and curing: Using a conventional optical fiber core rod as the substrate, the coating solution is applied to the outer surface of the optical fiber core rod in a single layer, with the coating thickness controlled between 20 and 50 μm; ultraviolet light curing is used for curing, with a curing light intensity of 800–1200 mW / cm². 2 With a curing time of 2–5 seconds, a side-emitting optical fiber with a single-layer coating structure was obtained.

[0012] Preferably, the auxiliary additives are one or a combination of two non-fluorinated leveling agents and defoamers, with the total addition amount not exceeding 1% of the total mass of the coating; the ultraviolet photoinitiator is any one of 1173 and 184 ultraviolet photoinitiators.

[0013] Preferably, the speed of the low-speed stirring in step S1 is 200-500 r / min; the speed of the low-speed stirring in step S3 is 800-1200 r / min.

[0014] Preferably, the coating is a solvent-free system and does not contain any organic solvents.

[0015] Preferably, the refractive index of the single-layer functional coating is 1.39 to 1.42, the optical fiber sidewall emits light uniformly without bright or dark spots, and the coating adhesion level is 0.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Precise and controllable optical performance: This invention uses a multifunctional fluorinated resin compounded with a specific ratio of nanoparticles, which can precisely control the refractive index of the coating after curing to a stable range of 1.39~1.42, perfectly matching the refractive index of the core layer of ordinary optical fibers. The light leakage is uniform, which completely solves the problems of uneven light emission and messy light spots in traditional optical fibers. The side-emitting effect is soft and uniform.

[0017] 2. Excellent particle dispersibility and no agglomeration defects: Using a special fluorinated modified dispersant, it is compatible with both fluorinated resin matrix and inorganic nanoparticles. It can effectively coat nanoparticles and reduce particle surface energy, eliminating particle agglomeration, sedimentation and stratification from the root. The coating system has strong stability, does not deteriorate during long-term storage, and the coating film has uniform light transmission and no fogging.

[0018] 3. Simple process and low production cost: Abandoning the traditional double-layer coating composite structure, it adopts a single-layer one-time coating and curing process, which simplifies the production process, improves production efficiency, reduces equipment investment and labor costs, and is suitable for large-scale industrial production.

[0019] 4. Excellent overall coating performance: The multifunctional resin has a high cross-linking density after curing, resulting in strong coating adhesion, bending resistance, yellowing resistance, and excellent weather resistance. It exhibits no peeling, flaking, or aging after long-term use, significantly extending the service life of optical fibers. The solvent-free formula is environmentally friendly and non-toxic, making it suitable for various civilian, medical, and commercial applications.

[0020] 5. Wide adaptability: It can be adapted to various conventional quartz optical fibers and plastic optical fiber cores without the need for customized special substrates. It has strong versatility and can meet the production needs of side-emitting optical fibers in different scenarios. Attached Figure Description

[0021] Figure 1 A flowchart illustrating a preferred embodiment of the method for preparing a photocurable coating for side-emitting optical fibers provided by the present invention; Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0023] Example 1: This invention provides a method for preparing a photocurable coating for side-emitting optical fibers, comprising the following steps.

[0024] Weigh the fluorinated polymeric dispersant according to the formula ratio and add it to a portion of the multifunctional fluorinated acrylate resin. Stir at a low speed of 500 to 800 r / min for 3 to 5 minutes at room temperature to ensure the dispersant is fully dissolved in the resin and forms a homogeneous premix. Then, weigh the inorganic nanoparticles according to the formula ratio and add them to the premix. First, stir at a low speed of 500 to 800 r / min for 10 minutes to allow the nanoparticles to initially impregnate the resin system. Then, use a high-speed disperser at a high speed of 3000 to 4000 r / min for 20 to 30 minutes to initially break up the agglomerates between the nanoparticles using high-speed shear force, forming a pre-dispersed slurry.

[0025] The high-speed dispersed mixture obtained in the above steps is fed into a sand mill, and wet fine grinding is performed using zirconia grinding beads as the grinding medium. The diameter of the zirconia grinding beads is preferably 0.3 to 0.8 mm, and the filling rate is controlled at 60% to 80% of the sand mill cavity volume. The grinding time is controlled at 30 to 40 minutes, and the particle size of the material is monitored in real time during the grinding process until the particle size D50 is less than or equal to 50 nm (i.e., more than 50% of the particles have a particle size of no more than 50 nm), to ensure that the inorganic nanoparticles are uniformly dispersed throughout the resin system without agglomeration residue.

[0026] Under normal temperature and light-protected conditions, add the remaining multifunctional fluorinated acrylate resin, UV initiator, and auxiliary agents to the homogenized material from step S2. Stir at a low speed of 800 to 1200 rpm for 15 to 20 minutes to ensure thorough mixing of all components. After stirring, filter the mixture through a 200 to 400 mesh screen to remove any small amounts of large particles, resulting in a homogeneous and stable UV-curable coating stock solution. The obtained coating stock solution is a colorless or slightly yellow transparent viscous liquid, without added solvent, and can be directly used in subsequent coating processes.

[0027] A conventional optical fiber core rod is selected as the substrate, which can be a quartz optical fiber core rod or a plastic optical fiber core rod. A single-layer coating process is used to uniformly coat the coating solution prepared in step S3 onto the outer surface of the optical fiber core rod. The coating method can be dip coating, spray coating, or mold coating. The coating thickness is controlled between 20 and 50 micrometers. After coating, the coated optical fiber is immediately placed in an ultraviolet curing device for curing. The curing process parameters are: ultraviolet light intensity of 800 to 1200 mW / cm², curing time of 2 to 5 seconds. Under ultraviolet light irradiation, the photoinitiator in the coating absorbs ultraviolet light energy and generates free radicals, which initiate free radical polymerization of the acrylate double bonds in the multifunctional fluorinated acrylate resin, forming a highly cross-linked three-dimensional network structure, allowing the coating to rapidly cure into a film within seconds. After curing, a uniform and dense single-layer functional coating is formed on the outer surface of the optical fiber core rod, resulting in a side-emitting optical fiber with a single-layer coating structure.

[0028] The fabricated side-emitting optical fiber consists of an inner fiber core and an outer single-layer photocurable coating. When light is transmitted in the fiber core, it is scattered when it encounters the uniformly dispersed inorganic nanoparticles in the coating. Some of the light is emitted uniformly from the sidewall of the optical fiber, achieving a uniform side-emitting effect.

[0029] Example 2: This embodiment provides a specific formulation and preparation method for a photocurable coating for side-emitting optical fibers.

[0030] Raw material ratio: ; Preparation process: S1. Pre-dispersion treatment: Weigh 0.32g of fluorine-modified polymeric dispersant and add it to 20g of tetrafunctional fluorinated acrylate resin. Stir at 600r / min for 4min to form a uniform premix. Add 4g of 50nm nano-silica and premix at 600r / min for 10min, then disperse at 3500r / min for 25min.

[0031] S2. Fine grinding and homogenization: The high-speed dispersed mixture is fed into a sand mill, using 0.5mm zirconia grinding beads with a filling rate of 70%, and wet grinding for 35 minutes, controlling the particle size D50 of the material to be less than or equal to 50nm.

[0032] S3. System compounding and blending: Add the remaining tetrafunctional fluorinated acrylate resin (to a total of 91g), 2.5g of 1173 UV initiator, and 0.18g of auxiliary additives to the homogenized material. Stir at 1000r / min for 18min at room temperature and in the dark. Filter through a 300-mesh filter to remove impurities and obtain the UV-curable coating stock solution.

[0033] S4. Single-layer coating and curing: Using a conventional quartz fiber core rod as the substrate, the coating solution is applied to the outer surface of the fiber core rod in a single layer using an dip-coating method, with the coating thickness controlled at 30 micrometers. Curing is then performed using ultraviolet light curing equipment at a light intensity of 1000 mW / cm² for 3 seconds, resulting in a single-layer coated side-emitting optical fiber.

[0034] Performance test results: ; Example 3: This embodiment provides a specific formulation and preparation method for another photocurable coating for side-emitting optical fibers.

[0035] Raw material ratio: ; Preparation process: S1. Pre-dispersion treatment: Weigh 0.64g of fluorine-modified polymeric dispersant and add it to 20g of hexafunctional fluorinated acrylate resin. Stir at 600r / min for 4min to form a uniform premix. Add 8g of 50nm nano-zirconia and premix at 600r / min for 10min, then disperse at 3500r / min for 25min.

[0036] S2. Fine grinding and homogenization: The high-speed dispersed mixture is fed into a sand mill, using 0.5mm zirconia grinding beads with a filling rate of 70%, and wet grinding for 35 minutes, controlling the particle size D50 of the material to be less than or equal to 50nm.

[0037] S3. System compounding and blending: Add the remaining hexafunctional fluorinated acrylate resin (to a total of 87g), 3.5g of 184 UV initiator, and 0.86g of auxiliary additives to the homogenized material. Stir at 1000r / min for 18min at room temperature and in the dark. Filter through a 300-mesh filter to remove impurities and obtain the UV-curable coating stock solution.

[0038] S4. Single-layer coating and curing: Using a conventional plastic optical fiber core rod (PMMA material) as the substrate, the coating solution is applied to the outer surface of the optical fiber core rod in a single layer using a mold coating method, with the coating thickness controlled at 40 micrometers. Curing is then performed using an ultraviolet curing device with a light intensity of 1000 mW / cm² and a curing time of 4 seconds, resulting in a single-layer coated side-emitting optical fiber.

[0039] Performance test results: ; Example 4: This embodiment provides a specific formulation and preparation method for another type of photocurable coating for side-emitting optical fibers.

[0040] Raw material ratio: ; Preparation process: S1. Pre-dispersion treatment: Weigh 0.48g of fluorine-modified polymeric dispersant and add it to 20g of trifunctional fluorinated acrylate resin. Stir at a low speed of 600r / min for 4min to form a uniform premix. Add 6g of nano-titanium dioxide with a particle size of 50nm, premix at a low speed of 600r / min for 10min, and then disperse at a high speed of 3500r / min for 25min.

[0041] S2. Fine grinding and homogenization: The high-speed dispersed mixture is fed into a sand mill, using 0.5mm zirconia grinding beads with a filling rate of 70%, and wet grinding for 35 minutes, controlling the particle size D50 of the material to be less than or equal to 50nm.

[0042] S3. System compounding and blending: Add the remaining trifunctional fluorinated acrylate resin (to a total of 89g), 3g of 1173 UV initiator, and 0.52g of auxiliary additives to the homogenized material. Stir at 1000r / min for 18min at room temperature and in the dark. Filter through a 300-mesh filter to remove impurities and obtain the UV-curable coating stock solution.

[0043] S4. Single-layer coating and curing: Using a conventional quartz fiber core rod as the substrate, the coating solution is applied to the outer surface of the fiber core rod in a single layer using a spraying method, with the coating thickness controlled at 25 micrometers. Curing is then performed using ultraviolet light curing equipment at a light intensity of 1000 mW / cm² and a curing time of 2.5 s, resulting in a single-layer coated side-emitting optical fiber.

[0044] Performance test results: ; The present invention provides a method for preparing a photocurable coating for side-emitting optical fibers, the working principle of which is as follows: Firstly, at the coating formulation design level, multifunctional fluorinated acrylate resin is used as the film-forming matrix. Due to the strong electronegativity and low polarizability of fluorine atoms, fluorinated resin has a natural low refractive index characteristic (usually 1.35 to 1.43), providing an optical basis for the low refractive index of the coating. By doping 4% to 8% of inorganic nanoparticles (nano-silica, nano-titanium dioxide, or nano-zirconia) into the multifunctional fluorinated resin, the refractive index can be finely adjusted without significantly changing the overall refractive index of the coating, so that it is stably controlled within a precise range of 1.39 to 1.42, perfectly matching the refractive index of ordinary optical fiber core rods.

[0045] Secondly, at the dispersion technology level, this invention uses a fluorinated modified polymeric dispersant to solve the compatibility problem between fluorinated resins and inorganic nanoparticles. The molecular structure of this dispersant contains both fluorinated compatible segments and inorganic particle anchoring groups. The fluorinated compatible segments are completely compatible with the fluorinated resin matrix, ensuring that the dispersant is uniformly distributed in the resin system. The inorganic particle anchoring groups are coated on the surface of inorganic nanoparticles through physical adsorption or chemical bonding, reducing the surface energy of the particles and generating a steric hindrance effect, effectively preventing particle aggregation and sedimentation. Through a three-stage dispersion process of pre-dispersion, high-speed shearing, and wet sand milling, the nanoparticles achieve a uniform dispersion state with a D50 of less than or equal to 50 nm in the fluorinated resin system, completely solving the optical inhomogeneity problem caused by particle aggregation.

[0046] Furthermore, at the coating process level, this invention abandons the traditional double-layer coating structure (inner low-refractive-index light-transmitting layer plus outer scattering and light-emitting layer), and adopts a single-layer, one-time coating and curing process. Since the coating itself integrates low-refractive-index characteristics and uniform scattering function, only one coating and UV curing are needed on the surface of the optical fiber core rod to form a single-layer functional coating with both light transmission and scattering functions. Under UV irradiation, the UV initiator generates free radicals, initiating a free radical polymerization reaction of the acrylate double bonds in the multifunctional fluorinated acrylate resin, forming a highly cross-linked three-dimensional network structure. This allows the coating to cure rapidly within seconds, endowing it with excellent adhesion, bending resistance, and weather resistance.

[0047] Finally, when light propagates in the fiber core, it undergoes Mie scattering when it encounters the uniformly dispersed inorganic nanoparticles in the coating. Some of the light changes its propagation direction and exits from the fiber sidewall. Since the nanoparticles are uniformly distributed in the coating and the scattering point density is uniform, the luminous intensity is consistent at all points on the fiber sidewall, thus achieving a uniform and soft side-emitting effect.

[0048] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0049] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a photocurable coating for side-emitting optical fibers, characterized in that, Includes the following steps: A solvent-free UV-curable coating was prepared by applying the coating to the surface of an optical fiber core rod using a single-layer, single-coat process and then curing it. After curing, only a single functional coating layer is formed. The coating uses a multifunctional fluorinated acrylate resin as the film-forming matrix, doped with inorganic nano-scattering particles, and modified by a fluorinated polymeric dispersant. After curing, the refractive index of the coating is stably controlled between 1.39 and 1.

42. The fluorinated polymeric dispersant has both fluorine-compatible segments and inorganic particle anchoring groups, which enables the inorganic nanoparticles to be uniformly dispersed in the fluorinated resin system without agglomeration or sedimentation.

2. The method for preparing a photocurable coating for side-emitting optical fibers according to claim 1, characterized in that: The raw material components of the coating, by mass percentage, include: 87%–91% multifunctional fluorinated acrylate resin, 4%–8% inorganic nanoparticles, 2%–4% ultraviolet photoinitiator, and 0.2%–1% auxiliary additives. The amount of fluorinated modified polymer dispersant added is 5%–10% of the mass of inorganic nanoparticles. The total mass percentage of each component is 100%.

3. The method for preparing a photocurable coating for side-emitting optical fibers according to claim 1, characterized in that: The multifunctional fluorinated acrylate resin is any one or more of the following: trifunctional fluorinated acrylate resin, tetrafunctional fluorinated acrylate resin, and hexafunctional fluorinated acrylate resin, blended in any proportion.

4. The method for preparing a photocurable coating for side-emitting optical fibers according to claim 1, characterized in that: The inorganic nanoparticles are any single type of nano-silica, nano-titanium dioxide, or nano-zirconium dioxide, with a particle size of 20–80 nm.

5. The method for preparing a photocurable coating for side-emitting optical fibers according to claim 1, characterized in that: The fluorinated polymeric dispersant is a fluorinated anchoring polymeric dispersant that is completely compatible with multifunctional fluorinated acrylate resins and can surface-coat and modify inorganic nanoparticles to inhibit particle aggregation.

6. The method for preparing a photocurable coating for side-emitting optical fibers according to claim 1, characterized in that: Specifically, the process steps include the following: S1. Pre-dispersion treatment: Disperse the fluorinated polymeric dispersant in part of the multifunctional fluorinated acrylate resin and stir at low speed for 3-5 min to form a uniform premix; add the measured amount of inorganic nanoparticles, premix at low speed for 10 min, and then disperse at high speed of 3000-4000 r / min for 20-30 min to initially break up the particle agglomerates. S2. Fine grinding and homogenization: The mixture obtained in step S1 is subjected to wet sand milling for 30 to 40 minutes, and the particle size D50 is controlled to be ≤50nm to achieve uniform dispersion of inorganic nanoparticles throughout the entire domain. S3. System compounding and mixing: Under normal temperature and light-protected environment, add the remaining multifunctional fluorinated acrylate resin, ultraviolet photoinitiator and auxiliary additives to the ground and homogenized material, stir at low speed of 800-1200r / min for 15-20min, and after thorough mixing, filter to remove impurities to obtain the UV-curable coating stock solution. S4. Single-layer coating and curing: Select a conventional optical fiber core rod as the substrate, and apply the coating solution to the outer surface of the optical fiber core rod in a single layer, with the coating thickness controlled between 20 and 50 μm. Curing is performed using ultraviolet light curing technology, with a curing light intensity of 800–1200 mW / cm². 2 With a curing time of 2–5 seconds, a side-emitting optical fiber with a single-layer coating structure was obtained.

7. The method for preparing a photocurable coating for side-emitting optical fibers according to claim 6, characterized in that: The auxiliary additives are one or a combination of two non-fluorinated leveling agents and defoamers, with the total addition amount not exceeding 1% of the total mass of the coating; the ultraviolet photoinitiator is any one of 1173 and 184 ultraviolet photoinitiators.

8. The method for preparing a photocurable coating for a side-emitting optical fiber according to claim 6, characterized in that: The speed of the low-speed stirring in step S1 is 200-500 r / min; the speed of the low-speed stirring in step S3 is 800-1200 r / min.

9. The method for preparing a photocurable coating for side-emitting optical fibers according to claim 1, characterized in that: The coating is a solvent-free system and contains no organic solvents.

10. A method for preparing a photocurable coating for a side-emitting optical fiber according to any one of claims 1-9, characterized in that: The single-layer functional coating has a refractive index of 1.39 to 1.42, emits light uniformly from the fiber sidewall without any bright or dark spots, and has an adhesion rating of 0.

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