Low-refractive-index UV resin for silane modified optical fiber and preparation method of low-refractive-index UV resin

Abstract

The invention relates to the field of light-cured oligomers, and discloses a low-refractive-index UV resin for silane-modified optical fibers and a preparation method thereof.The preparation method comprises the steps that fluorine-containing polyether polyol, diisocyanate, hydroxyl (meth) acrylate and mercaptosiloxane serve as main raw materials, firstly, the diisocyanate and the hydroxyl (meth) acrylate are adopted for pre-blocking, and then the low-refractive-index UV resin for the silane-modified optical fibers is obtained; and finally, introducing a sulfydryl siloxane structure through Michael addition, so as to prepare the low-refractive-index UV resin which is high in reaction activity, high in permeability, high in adhesive force and stable in performance.

Description

Technical Field

[0001] The invention relates to the technical field of photocurable oligomers, in particular to a low-refractive-index UV resin for silane-modified optical fiber and a preparation method thereof. Background Art

[0002] Optical fiber coating is an important component of the optical fiber manufacturing process. It is mainly used in the drawing process after the optical fiber preform rod is used to protect the optical fiber from mechanical damage and environmental factors, extend the service life of the optical fiber, and improve the mechanical strength of the optical fiber so that it can withstand various stresses during installation and use. It forms a total internal reflection structure with the core material of the optical fiber to ensure the effective transmission of optical signals and reduce signal loss.

[0003] In order to constrain the pump light to propagate in the optical fiber quartz cladding, the inner coating refractive index of the optical fiber used in the fiber laser is required to be low. Depending on the numerical aperture requirements of the optical fiber, the inner coating refractive index is generally less than 1.40. In addition to the refractive index requirements, the low-refractive-index optical fiber coating used in the fiber laser also needs to have a strong interface bonding force with the glass fiber, and the bonding force should not be weakened in a high temperature and high humidity environment to meet the use scenario requirements of the fiber laser.

[0004] Although the existing technology has made certain progress in the research and development of low-refractive index optical fiber coatings by introducing fluorinated polymers to reduce the refractive index of the material, it still faces many challenges. For example, while ensuring optical performance, low-refractive index materials need to take into account reasonable adhesion to avoid the coating from falling off due to insufficient adhesion during long-term use in high temperature and high humidity environments, thereby affecting the performance of the optical fiber. At present, most conventional optical fiber coatings modify the resin by adding silane coupling agents to the formula to improve adhesion to the glass fiber core. However, the compatibility between high-fluorine-containing formula coatings and silane coupling agents is poor, which often leads to a decrease in the clarity of the coating, or affects the stability of the coating system, shortens the shelf life of the coating, and further affects its adhesion to the optical fiber substrate. These problems have limited its large-scale promotion and application. Summary of the invention

[0005] In view of the deficiencies of the prior art, the present invention provides a low-refractive-index UV resin for silane-modified optical fiber with high reactivity, high permeability, high adhesion and stable performance and a preparation method thereof.

[0006] To achieve the above objectives, the present invention is implemented by the following technical scheme: a low-refractive-index UV resin for silane-modified optical fiber, wherein the low-refractive-index UV resin for silane-modified optical fiber has the following structure: Where n is a positive integer; R 1 is alkyl or absent; R2 , R 3 All are alkyl.

[0007] A method for preparing a low-refractive-index UV resin for silane-modified optical fiber comprises the following steps: S1. Add diisocyanate into a reaction kettle, add a catalyst, an inhibitor, and an antioxidant under stirring conditions, and control the reaction temperature at 50°C-70°C, then dropwise add (meth) acrylate hydroxy ester, react for 1h-3h, monitor the NCO content until it is lower than the theoretical value, and then cool to 40-60°C to continue the reaction; S2. Slowly add fluorinated polyether polyol while continuing the reaction, maintain the reaction temperature at 70°C-90°C, and continue the reaction until the NCO content is less than 0.02% or the NCO group disappears as confirmed by infrared spectroscopy; After the S3 and NCO groups disappear, the temperature needs to be lowered to 30°C-50°C, and a nucleophilic catalyst is added. Then, mercaptosiloxane is slowly added at 40-70°C, and the reaction is stirred for 1h-3h. The viscosity is tested and the reaction is stopped after reaching the standard to obtain a low-refractive-index UV resin for silane-modified optical fiber. During the reaction, the reaction endpoint is determined by titration and Fourier transform infrared spectroscopy.

[0008] Preferably, the diisocyanate is one or any combination of isophorone diisocyanate, hexamethylene diisocyanate, hydrogenated diphenylmethane diisocyanate, toluene diisocyanate and diphenylmethane diisocyanate.

[0009] Preferably, the mercaptosiloxane is any combination of one or more of mercaptoethyltrimethoxysilane, mercaptopropyltrimethoxysilane, mercaptoethyltriethoxysilane and mercaptopropyltriethoxysilane.

[0010] Preferably, the polymerization inhibitor is any combination of one or more of p-hydroxyanisole, hydroquinone, and tert-butylhydroquinone.

[0011] Preferably, the (meth)acrylate hydroxy ester is one or any combination of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, pentaerythritol triacrylate and pentaerythritol trimethacrylate.

[0012] Preferably, the fluorinated polyether polyol is any combination of one or more fluorinated polyether diols and fluorinated polyether polyols having a molecular weight of 500-5000.

[0013] Preferably, the nucleophilic catalyst is any combination of one or more of triphenylphosphine, triethylamine, N,N-dimethylbenzylamine and N,N-diethylbenzylamine.

[0014] Preferably, the antioxidant is any combination of one or more of butylated hydroxytoluene, antioxidant 168 and antioxidant 1010; The catalyst is one or more of organic tin, organic bismuth and organic silver in any combination.

[0015] Preferably, in the steps S1 to S3, the mass ratio of diisocyanate, catalyst, inhibitor, antioxidant, (methyl) hydroxy acrylate, fluorinated polyether polyol, nucleophilic catalyst and mercaptosiloxane is: (15-30): (0.02-0.1): (0.02-0.1): (0.02-0.1): (10-30): 100: (0.1-0.4): (8-15).

[0016] The present invention provides a low-refractive-index UV resin for silane-modified optical fiber and a preparation method thereof. The resin has the following beneficial effects: 1. The present invention introduces the property of low refractive index of fluorine by using polyether polyol with high fluorine content, and connects mercaptosiloxane into the structure by Michael addition using nucleophilic catalyst, so as to synthesize low refractive index resin with excellent stability, which not only has a refractive index of less than 1.37, but also has high reactivity, high permeability and high adhesion. Compared with the few UV low refractive index products for optical fiber on the market, it has obvious advantages in performance; 2. The preparation process of the present invention is simple and controllable, more industrialized than the modification process using hydrosilylation, easier to popularize and promote, and has strong market competitiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the product structure of the present invention; Figure 2 It is a flow chart of the preparation method of the present invention. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the specification of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] Please refer to the attached Figure 1 -Attached Figure 2 , Example 1: In this embodiment, a low refractive index UV resin for silane-modified optical fiber is prepared according to the following steps: S1, put 44.46g of isophorone diisocyanate into a reactor, start stirring, add 0.10g of organotin, 0.05g of p-hydroxyanisole, 0.05g of butylated hydroxytoluene, add 11.02g of hydroxy acrylate and 48.80g of pentaerythritol triacrylate dropwise, the reaction temperature is 70°C, the reaction time is 2.5h, until NCO is less than the theoretical value, and the temperature is lowered to 50°C; S2, slowly add 200g of fluorinated polyether diol with a molecular weight of 2000, and the reaction temperature is 85°C, until the NCO content is lower than 0.02% or the infrared disappears; S13, cooling to 40°C, adding 0.4g of triphenylphosphine, slowly adding 19.64g of mercaptopropyltrimethoxysilane, the reaction temperature is 60°C, reacting until the viscosity reaches the standard range, stopping the reaction, and obtaining a low refractive index UV resin for silane-modified optical fiber; Embodiment 2: In this embodiment, a low refractive index UV resin for silane-modified optical fiber is prepared according to the following steps: S1, put 52.47g hydrogenated diphenylmethane diisocyanate into a reactor, start stirring, add 0.20g organotin, 0.20g p-hydroxyanisole, 0.10g dibutylhydroxytoluene, add 11.62g hydroxy acrylate and 30.85g pentaerythritol triacrylate dropwise, the reaction temperature is 70°C, the reaction time is 2.5h, until NCO is less than the theoretical value, and the temperature is lowered to 50°C; S2, slowly add 200g of fluorinated polyether diol with a molecular weight of 2000, and the reaction temperature is 85°C, until the NCO content is lower than 0.02% or the infrared disappears; S3, cooling to 40°C, adding 0.80g of triphenylphosphine, slowly adding 29.23g of mercaptopropyltrimethoxysilane, the reaction temperature is 60°C, reacting until the viscosity reaches the standard range, stopping the reaction, and obtaining a low refractive index UV resin for silane-modified optical fiber; Embodiment 3: In this embodiment, a low refractive index UV resin for silane-modified optical fiber is prepared according to the following steps: S1, put 33.64g hexamethylene diisocyanate into a reactor, start stirring, add 0.10g organotin, 0.10g p-hydroxyanisole, 0.10g butylated hydroxytoluene, add 11.02g hydroxy acrylate and 12.30g pentaerythritol triacrylate dropwise, the reaction temperature is 70°C, the reaction time is 2.5h, until NCO is less than the theoretical value, and the temperature is lowered to 50°C; S2, slowly add 200g of fluorinated polyether diol with a molecular weight of 2000, and the reaction temperature is 85°C, until the NCO content is lower than 0.02% or the infrared disappears; S3, cooling to 40°C, adding 0.2g triphenylphosphine, slowly adding 23.85g mercaptopropyltrimethoxysilane, the reaction temperature is 60°C, reacting until the viscosity reaches the standard range, stopping the reaction, and obtaining a low refractive index UV resin for silane-modified optical fiber; Embodiment 4: In this embodiment, a low refractive index UV resin for silane-modified optical fiber is prepared according to the following steps: S1, put 58.46g of isophorone diisocyanate into a reactor, start stirring, add 0.20g of organotin, 0.10g of p-hydroxyanisole, 0.10g of butylated hydroxytoluene, dropwise add 11.62g of hydroxy acrylate and 38.60g of pentaerythritol triacrylate, the reaction temperature is 70°C, the reaction time is 2.5h, until NCO is less than the theoretical value, and the temperature is lowered to 50°C; S2, slowly add 200g of fluorinated polyether diol with a molecular weight of 2000, and the reaction temperature is 85°C, until the NCO content is lower than 0.02% or the infrared disappears; S3, cooling to 40°C, adding 0.50g N,N-dimethylbenzylamine, slowly adding 23.85g mercaptopropyltriethoxysilane, the reaction temperature is 60°C, reacting until the viscosity reaches the standard range, stopping the reaction, and obtaining a low refractive index UV resin for silane-modified optical fiber; Embodiment 5: In this embodiment, a low refractive index UV resin for silane-modified optical fiber is prepared according to the following steps: S1, put 44.46g of isophorone diisocyanate into a reactor, start stirring, add 0.10g of organotin, 0.20g of p-hydroxyanisole, 0.20g of butylated hydroxytoluene, add 11.62g of hydroxy acrylate and 38.60g of pentaerythritol triacrylate dropwise, the reaction temperature is 70°C, the reaction time is 2.5h, until NCO is less than the theoretical value, and the temperature is lowered to 50°C; S2, slowly add 200g of fluorinated polyether diol with a molecular weight of 2000, and the reaction temperature is 85°C, until the NCO content is lower than 0.02% or the infrared disappears; S3, cooling to 40°C, adding 0.5g N,N-dimethylbenzylamine, slowly adding 23.85g mercaptopropyltriethoxysilane, the reaction temperature is 60°C, reacting until the viscosity reaches the standard range, stopping the reaction, and obtaining a low refractive index UV resin for silane-modified optical fiber; Embodiment 6: In this embodiment, a low refractive index UV resin for silane-modified optical fiber is prepared according to the following steps: S1, put 33.64g hexamethylene diisocyanate into a reactor, start stirring, add 0.05g organotin, 0.10g p-hydroxyanisole, 0.10g butylated hydroxytoluene, add 11.62g hydroxy acrylate and 20.80g pentaerythritol triacrylate dropwise, the reaction temperature is 70°C, the reaction time is 2.5h, until NCO is less than the theoretical value, and the temperature is lowered to 50°C; S2, slowly add 200g of fluorinated polyether diol with a molecular weight of 2000, and the reaction temperature is 85°C, until the NCO content is lower than 0.02% or the infrared disappears; S3, cool to 40°C, add 0.50g N,N-dimethylbenzylamine, slowly add 16.02g mercaptopropyltriethoxysilane, reaction temperature 60°C, react until the viscosity reaches the standard range, stop the reaction, and obtain a low refractive index UV resin for silane-modified optical fiber.

[0020] Comparative Example 1: A conventional cold-blended silicone coupling agent low-refractive index optical fiber coating resin was selected as a comparative example, product model: DSM-DF-0016, manufacturer: Royal DSM Group of the Netherlands; its appearance is turbid liquid.

[0021] Comparative experiment: The resins obtained in Examples 1-6 were mixed evenly according to 100 g of resin and 3 g of photoinitiator 184, and after being fully dissolved, they were defoamed using a high-speed desktop centrifuge. The coating thickness was 20 μm, and the coating was photocured using a UV track curing machine with a curing energy of 600-800 mJ / cm 2 .

[0022] 100 g of the product of the comparative example and 2 g of the silane coupling agent KH570 / KH572 were mixed evenly and then heated for curing, with a dry film thickness of 20 μm.

[0023] Performance Test: (1) Adhesion: Adhesion is tested using the 100-grid method according to standard GB / T9286-1998 “Scratching test for paint and varnish films”.

[0024] (2) Refractive index: Tested using an electronic refractive index instrument. The results are shown in Table 1: Table 1. Performance tests of the resins of Examples 1-6 and Comparative Example 1 Adhesion Refractive Index Appearance Example 1 0 1.363 clarify Example 2 0 1.366 clarify Example 3 0 1.365 clarify Example 4 0 1.362 clarify Example 5 0 1.368 clarify Example 6 0 1.367 clarify Comparative Example 1 1 1.412 turbid From the experimental results, compared with the comparative product (conventional cold-blended silicone coupling agent low-refractive index resin on the market), the resin prepared by the present invention has obvious advantages in refractive index, clarity and adhesion performance.

[0025] On the one hand, the refractive index of the resin of the present invention is lower than 1.37, which meets the application requirements of low refractive index of the inner coating of the optical fiber. This is mainly due to the introduction of fluorine-containing polyether polyols, which makes the resin have a lower polarizability, thereby reducing the refractive index. On the other hand, the adhesion test results show that the resin of the present invention can still maintain excellent adhesion under high temperature and high humidity environment, and its bonding with the optical fiber substrate will not be reduced due to environmental factors. The present invention introduces mercaptosiloxane into the resin system by Michael addition, which effectively improves the adhesion of the resin and forms a stronger interfacial bonding force with the optical fiber substrate. In addition, the present invention solves the problem of poor compatibility between conventional silane coupling agents and high-fluorine systems, and has better stability.

[0026] Experiments show that the synthesis method of the present invention can obtain a low-refractive-index UV resin with high reactivity, high permeability, high adhesion and good stability, which meets the requirements of optical fiber coating for low refractive index and high stability. The entire preparation process is simple and controllable, which is more industrialized than the modification process using hydrosilylation, and is easy to popularize and promote. Therefore, it has good prospects for industrial application.

[0027] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A low refractive index UV resin for silane-modified optical fiber, characterized in that: A low refractive index UV resin for silane-modified optical fiber has the structure shown below: Wherein, n is a positive integer; R1 is an alkyl group or does not exist; R2 and R3 are both alkyl groups.

2. A method for preparing a low-refractive-index UV resin for silane-modified optical fiber as claimed in claim 1, characterized in that: The following steps are involved: S1. Add diisocyanate into a reaction kettle, add a catalyst, an inhibitor, and an antioxidant under stirring conditions, and control the reaction temperature at 50°C-70°C, then dropwise add (meth) acrylate hydroxy ester, react for 1h-3h, monitor the NCO content until it is lower than the theoretical value, and then cool to 40-60°C to continue the reaction; S2. Slowly add fluorinated polyether polyol while continuing the reaction, maintain the reaction temperature at 70°C-90°C, and continue the reaction until the NCO content is less than 0.02% or the NCO group disappears as confirmed by infrared spectroscopy; After the S3 and NCO groups disappear, the temperature needs to be lowered to 30°C-50°C, and a nucleophilic catalyst is added. Then, mercaptosiloxane is slowly added at 40-70°C, and the reaction is stirred for 1h-3h. The viscosity is tested and the reaction is stopped after reaching the standard to obtain a low-refractive-index UV resin for silane-modified optical fiber. During the reaction, the reaction endpoint is determined by titration and Fourier transform infrared spectroscopy.

3. The method for preparing a low-refractive-index UV resin for silane-modified optical fiber according to claim 2, characterized in that: The diisocyanate is one or any combination of isophorone diisocyanate, hexamethylene diisocyanate, hydrogenated diphenylmethane diisocyanate, toluene diisocyanate and diphenylmethane diisocyanate.

4. The method for preparing a low-refractive-index UV resin for silane-modified optical fiber according to claim 2, characterized in that: The mercaptosiloxane is any combination of one or more of mercaptoethyltrimethoxysilane, mercaptopropyltrimethoxysilane, mercaptoethyltriethoxysilane and mercaptopropyltriethoxysilane.

5. The method for preparing a low-refractive-index UV resin for silane-modified optical fiber according to claim 2, characterized in that: The polymerization inhibitor is any combination of one or more of p-hydroxyanisole, hydroquinone and tert-butylhydroquinone.

6. The method for preparing a low-refractive-index UV resin for silane-modified optical fiber according to claim 2, characterized in that: The (meth) hydroxy acrylate is one or any combination of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, pentaerythritol triacrylate and pentaerythritol trimethacrylate.

7. The method for preparing a low-refractive-index UV resin for silane-modified optical fiber according to claim 2, characterized in that: The fluorinated polyether polyol is any combination of one or more fluorinated polyether diols and fluorinated polyether polyols having a molecular weight of 500-5000.

8. The method for preparing a low-refractive-index UV resin for silane-modified optical fiber according to claim 2, characterized in that: The nucleophilic catalyst is any combination of one or more of triphenylphosphine, triethylamine, N,N-dimethylbenzylamine and N,N-diethylbenzylamine.

9. The method for preparing a low-refractive-index UV resin for silane-modified optical fiber according to claim 2, characterized in that: The antioxidant is any combination of one or more of butylated hydroxytoluene, antioxidant 168 and antioxidant 1010; The catalyst is one or more of organic tin, organic bismuth and organic silver in any combination.

10. The method for preparing a low-refractive-index UV resin for silane-modified optical fiber according to claim 2, characterized in that: In the steps S1 to S3, the mass ratios of diisocyanate, catalyst, inhibitor, antioxidant, (methyl) hydroxy acrylate, fluorinated polyether polyol, nucleophilic catalyst and mercaptosiloxane are: (15-30): (0.02-0.1): (0.02-0.1): (0.02-0.1): (10-30): 100: (0.1-0.4): (8-15).

Images