Preparation method and application of dumbbell-shaped difunctional hindered amine light stabilizer

Abstract

The invention relates to a dumbbell-shaped difunctional hindered amine light stabilizer and a preparation method and application thereof, and the preparation method comprises the following steps: taking N-n-butyl-2, 2, 6, 6-tetramethyl-4-piperidylamine (1) and 2, 4, 6-trichloro-1, 3, 5-triazine (2) as raw materials, and synthesizing an intermediate (3) through nucleophilic substitution; dropwise adding a hydrogen peroxide aqueous solution into the intermediate (3), adding a reaction solvent and a catalyst, and performing oxidation reaction to obtain an intermediate (4); taking the intermediate (4) and cyclohexane as raw materials, adding a reaction solvent, an oxidizing agent and a catalyst, and performing nucleophilic substitution reaction to obtain an intermediate (5); and carrying out coupling reaction on the intermediate (5) and aliphatic or aromatic diamine under the protection of N2 to obtain the dumbbell-shaped difunctional hindered amine light stabilizer. According to the light stabilizer provided by the invention, the light aging process of a polymer can be more effectively prevented, and the stability of a material under light irradiation is improved; in a high-temperature processing or using process, the material is not easy to decompose or volatilize and high in thermal stability, and the structure of the material has excellent light stability and molecular stability.

Description

Technical Field

[0001] This invention belongs to the field of light stabilizers, specifically, it relates to a dumbbell-shaped bifunctional hindered amine light stabilizer, its preparation method, and its application. Background Technology

[0002] Plastics, coatings, and other polymer materials are prone to chemical changes such as chemical bond breakage and cross-linking under the combined effects of light, heat, and oxygen, resulting in aging phenomena such as yellowing and cracking, which leads to a decline in mechanical properties. At the same time, other physical properties also change, which greatly shortens the service life of polymer material products or even makes them lose their usability.

[0003] To prevent or delay photoaging of polymer materials, light stabilizers are required. Light stabilizers can be classified according to their mechanism of action into free radical scavengers, ultraviolet absorbers, light shielding agents, and quenchers. Among them, hindered amine light stabilizers can effectively capture free radicals generated during the photoaging process of polymer materials, preventing the photoaging chain reaction, thereby improving the aging resistance of the material and extending its service life.

[0004] The patent publication number "CN119080749A" discloses a method for preparing hindered amine light stabilizers. This method uses cyanuric chloride, 2,2,6,6-tetramethyl-4-piperidinylbutylamine, ethanolamine, and cyclohexane in a multi-step reaction to prepare the hindered amine light stabilizer Tinuvin152. The problem with this method is:

[0005] 1. Due to the low content of piperidine amine, which plays a major role, its light stabilizing effect is relatively weak. During long-term outdoor use or in environments with stringent light stability requirements, it may not be able to provide sufficient and durable protection for polymer materials.

[0006] 2. Due to its small molecular weight or weak binding force with polymer materials, it is prone to migration and extraction, resulting in the loss of light stabilizer and affecting the long-term light stability of polymer materials. Summary of the Invention

[0007] This invention provides a method for preparing and applying a dumbbell-shaped bifunctional hindered amine light stabilizer to address the shortcomings of existing technologies, such as poor light stability.

[0008] To achieve the objectives of this invention, the following technical solution is adopted:

[0009] A method for preparing a dumbbell-shaped bifunctional hindered amine light stabilizer includes the following steps:

[0010] Step S1: Using N-n-butyl-2,2,6,6-tetramethyl-4-piperidinamine (1) and 2,4,6-trichloro-1,3,5-triazine (2) as raw materials, an intermediate (3) is synthesized by nucleophilic substitution;

[0011] Step S2: Add hydrogen peroxide aqueous solution to intermediate (3), add reaction solvent and catalyst, and obtain intermediate (4) through oxidation reaction;

[0012] Step S3: Using intermediate (4) and cyclohexane as raw materials, add reaction solvent, oxidant and catalyst, and obtain intermediate (5) through nucleophilic substitution reaction;

[0013] Step S4: The intermediate (5) and an aliphatic or aromatic diamine are coupled under N2 protection to obtain a dumbbell-shaped bifunctional hindered amine light stabilizer.

[0014] Furthermore, in step S1, the molar ratio of N-n-butyl-2,2,6,6-tetramethyl-4-piperidineamine (1) and 2,4,6-trichloro-1,3,5-triazine (2) is 2:1.

[0015] Furthermore, in step S2, the molar ratio of 2-chloro-4,6-di-[N-n-butyl-N-(2,2,6,6-tetramethyl-4-piperidinyl)amino]-1,3,5-triazine (3) to 30% hydrogen peroxide aqueous solution is 1:1.1-1.5.

[0016] Furthermore, in step S3 above, the molar ratio of intermediate (4) to cyclohexane is 1:2-2.4.

[0017] Furthermore, in step S4 above, the molar ratio of intermediate (5) to aliphatic or aromatic diamine is 2-2.5:1.

[0018] Further, the coupling reaction in step S4 above specifically involves: dissolving intermediate (5) and an aliphatic or aromatic diamine in a reaction solvent, adding a catalyst, and reacting at 110°C for 12 hours under nitrogen protection. Extraction is performed, the organic phase is collected, and then washed several times with water. The mixture is dried with anhydrous sodium sulfate to obtain a crude product. The crude product is further purified by column chromatography to obtain a dumbbell-shaped bifunctional hindered amine light stabilizer.

[0019] Furthermore, in step S4 above: the reaction solvent is one of toluene, xylene, and benzene, and the catalyst is one of NaOH aqueous solution or NaHCO3 aqueous solution with a mass concentration of 10-30%.

[0020] Furthermore, the dumbbell-shaped bifunctional hindered amine light stabilizer prepared by the above method.

[0021] Furthermore, the above-mentioned dumbbell-shaped bifunctional hindered amine light stabilizer is applied in PE.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. Existing technologies rely on the limited sites of a single molecule to capture free radicals generated by polymer photoaging. Under high light intensity or long-term aging conditions, the active sites are easily saturated, leading to a gradual decrease in photostability. Furthermore, the small molecular weight makes it prone to migration to the material surface or extraction by solvents over time, resulting in reduced photostability. Poor molecular structure symmetry also limits thermal stability, making it susceptible to decomposition or volatilization during high-temperature processing, thus reducing its effective content. Therefore, this invention aims to create a high-performance photostability agent through a "dumbbell-shaped structure + dual-functional integration" design, better suited to the current demand in polymer materials for "long-lasting anti-aging + multi-performance composite."

[0024] 2. The dumbbell-type bifunctional hindered amine light stabilizer of the present invention has an aliphatic or aromatic diamine connected to two hindered amines, which is equivalent to introducing two stable centers in one molecule, that is, one molecule contains four hindered amine groups, which can provide more active sites to capture free radicals, and can more effectively prevent the photoaging process of polymers and improve the stability of materials under light irradiation.

[0025] 3. The dumbbell-shaped bifunctional hindered amine light stabilizer of the present invention, with its aliphatic or aromatic diamine linkage structure, can increase the rigidity and symmetry of the molecule, thereby enhancing the interaction between the light stabilizer and the polymer. This helps to improve the thermal stability of the light stabilizer, making it less prone to decomposition or volatilization during high-temperature processing or use, and thus better maintaining its light stability performance.

[0026] 4. The dumbbell-shaped bifunctional hindered amine light stabilizer of the present invention has an N-alkoxy group that can serve as a flame-retardant functional group. Through the self-synergistic effect between the hindered amine group and the N-alkoxy group, it can improve the light stability of the material while increasing its flame retardancy, thus giving the molecule bifunctionality.

[0027] 5. First, intermediate (3) is generated by nucleophilic substitution reaction of N-n-butyl-2,2,6,6-tetramethyl-4-piperidineamine and 2,4,6-trichloro-1,3,5-triazine. This intermediate (3) has a hindered amine core skeleton, which lays the foundation for subsequent functionalization modification. The intermediate (3) can be further oxidized to convert the piperidinamine structure in the intermediate (3) into a nitric oxide radical structure, thereby enhancing the photostable active site of the hindered amine. Then, intermediate (4) is nucleophilically substituted to obtain intermediate (5), which introduces more active groups that can be used for subsequent coupling into its molecular structure, resulting in better reactivity and structural plasticity. Next, intermediate (5) is reacted with aliphatic or aromatic diamines to form a dumbbell-shaped structure through coupling reaction, finally yielding a bifunctional hindered amine photostable agent. This structure has both excellent photostable performance and molecular stability.

[0028] 6. The preparation method provided by this invention does not involve dangerous process steps such as high temperature and high pressure, is safe and reliable, and is easy to implement. In the entire preparation process, each step is interconnected and synergistically optimized, so the preparation method has a high yield. Attached Figure Description

[0029] Figure 1 The 1H NMR spectrum of the dumbbell-shaped bifunctional hindered amine light stabilizer synthesized in Example 1 of this invention;

[0030] Figure 2 Mass spectrometry of the dumbbell-shaped bifunctional hindered amine light stabilizer synthesized in Example 1 of this invention;

[0031] Figure 3 The graphs show the mechanical properties of the dumbbell-shaped bifunctional hindered amine light stabilizer synthesized in Embodiment 1 of this invention at different aging times in PE films. Figure 3 (a) Relationship between aging time and tensile strength retention rate at different addition amounts (%); Figure 3 (b) shows the relationship between aging time and elongation at break retention for different addition amounts. Detailed Implementation

[0032] To facilitate understanding of the present invention by those skilled in the art, a clear and complete description is provided below with reference to specific embodiments and figures. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention, and are not intended to limit the scope of the invention. Any equivalent modifications to the technical solutions of the present invention made by those skilled in the art through reading this specification are covered by the claims of the present invention.

[0033] This invention provides a dumbbell-shaped bifunctional hindered amine light stabilizer, which uses aliphatic or aromatic diamines as raw materials. The reaction equation for the synthesis product is as follows:

[0034]

[0035] A dumbbell-shaped bifunctional hindered amine light stabilizer has the following structural formula:

[0036]

[0037] Where: n = 1-3

[0038] Example 1: A method for preparing a dumbbell-shaped bifunctional hindered amine light stabilizer provided by the present invention includes the following steps:

[0039] S1. Dissolve 18.44 g of 2,4,6-trichloro-1,3,5-triazine in 200 mL of toluene. Under an ice-water bath, slowly add 42.42 g of N-n-butyl-2,2,6,6-tetramethyl-4-piperidinamine and react for 2 h. Then add 20 mL of 30% NaOH aqueous solution as a catalyst and continue the reaction at 70 °C for 14 h. After the reaction is complete, extract three times with 200 mL of water to separate the organic phase. Dry with anhydrous sodium sulfate, remove the solvent by rotary evaporation, and dry under vacuum to obtain intermediate (3). The intermediate (3) is 2-chloro-4,6-di-[N-n-butyl-N-(2,2,6,6-tetramethyl-4-piperidinyl)amino]-1,3,5-triazine, with a yield of about 46.2 g and a yield of 86%.

[0040] S2. Dissolve 14.381g of intermediate (3) in 60mL of methanol and stir at 15℃ for 10min. After dissolution, add 0.4g of sodium tungstate dihydrate, followed by slowly adding 3mL of 30% hydrogen peroxide aqueous solution. Heat to 25℃ and continue the reaction for 24h. A light pink solid appears in the system. Continue the reaction for 5h, collect the solid product by vacuum filtration, and dry it in a vacuum drying oven at 35℃ for 8h to obtain intermediate (4). The yield is about 12.15g, with a yield of 80%.

[0041] S3. In a 1000mL three-necked flask, 6g of intermediate (4) was dissolved in 600mL of methanol at room temperature by sonication. Then, 150mL of cyclohexane, 1.5255g of FeSO4, 15mL of water, 0.9mL of glacial acetic acid, and 2.625g of TBHP were added sequentially. The mixture was stirred at 55℃ for 0.5h. The temperature of the mixture was raised to 65℃, and 51.3mL of 30% hydrogen peroxide was slowly added dropwise to the reaction flask over 3h. After the addition was completed, the reaction was continued for 15h. After cooling naturally to room temperature, the solid impurities were filtered off. Dichloromethane and water were added to the reaction solution for extraction. The organic phase was collected, and the crude product was obtained by rotary evaporation and vacuum drying. The crude product was purified by column chromatography to obtain intermediate (5), with a yield of about 4.7g and a yield of 61%.

[0042] S4. Dissolve 11.72 g of intermediate (5) and 0.6 g of ethylenediamine in 200 mL of toluene and 2.12 g of 30% NaOH aqueous solution. React at 110 °C for 12 h under nitrogen protection. Extract the organic phase, collect it, and then wash it three times with 50 mL of water. Dry the phase with anhydrous sodium sulfate to obtain the crude product. Further purify the crude product by column chromatography to obtain a dumbbell-shaped bifunctional hindered amine light stabilizer with a yield of approximately 7.2 g (50%).

[0043] Example 2: A method for preparing a dumbbell-shaped bifunctional hindered amine light stabilizer provided by the present invention includes the following steps:

[0044] S1. Dissolve 18.44 g of 2,4,6-trichloro-1,3,5-triazine in 200 mL of toluene. Under an ice-water bath, slowly add 42.42 g of N-n-butyl-2,2,6,6-tetramethyl-4-piperidinamine and react for 2 h. Then add 20 mL of 30% KOH aqueous solution as a catalyst and continue the reaction at 70 °C for 14 h. After the reaction is complete, extract three times with 200 mL of water to separate the organic phase. Dry with anhydrous sodium sulfate, remove the solvent by rotary evaporation, and dry under vacuum to obtain intermediate (3), with a yield of about 43.51 g and a yield of 81%.

[0045] S2. Dissolve 14.381g of intermediate (3) in 60mL of toluene and stir at 15℃ for 10min. After dissolution, add 0.4g of sodium tungstate dihydrate, followed by slowly adding 3mL of 30% hydrogen peroxide aqueous solution. After heating to 25℃ and continuing the reaction for 24h, a light pink solid appears in the system. After continuing the reaction for 5h, collect the solid product by vacuum filtration and dry it in a vacuum drying oven at 35℃ for 8h to obtain intermediate (4), with a yield of about 11.24g and a yield of 74%.

[0046] S3. In a 1000mL three-necked flask, 6g of intermediate (4) was dissolved by sonication in 600mL of toluene at room temperature. Then, 150mL of cyclohexane, 1.5255g of FeSO4, 15mL of water, 0.9mL of glacial acetic acid, and 2.625g of TBHP were added sequentially. The mixture was stirred at 55℃ for 0.5h. The temperature of the mixture was raised to 65℃, and 51.3mL of 30% hydrogen peroxide was slowly added dropwise to the reaction flask over 3h. After the addition was completed, the reaction was continued for 15h. After cooling naturally to room temperature, the solid impurities were filtered off. Dichloromethane and water were added to the reaction solution for extraction. The organic phase was collected, and the crude product was obtained by rotary evaporation and vacuum drying. The crude product was purified by column chromatography to obtain intermediate (5), with a yield of about 4.31g and a yield of 56%.

[0047] S4. Dissolve 11.72 g of intermediate (5) and 0.6 g of ethylenediamine in 200 mL of toluene and 2.12 g of 30% NaOH aqueous solution. React at 110 °C for 18 h under nitrogen protection. Extract the organic phase, collect it, and then wash the organic phase three times with 50 mL of water. Dry the phase with anhydrous sodium sulfate to obtain the crude product. Further purify the crude product by column chromatography to obtain a dumbbell-shaped bifunctional hindered amine light stabilizer with a yield of approximately 6.9 g (48%).

[0048] Example 3: A method for preparing a dumbbell-shaped bifunctional hindered amine light stabilizer provided by the present invention includes the following steps:

[0049] S1. Dissolve 18.44 g of 2,4,6-trichloro-1,3,5-triazine in 200 mL of toluene. Under an ice-water bath, slowly add 42.42 g of N-n-butyl-2,2,6,6-tetramethyl-4-piperidinamine and react for 2 h. Then add 20 mL of 30% NaOH aqueous solution as a catalyst and continue the reaction at 70 °C for 10 h. After the reaction is complete, extract three times with 200 mL of water to separate the organic phase. Dry with anhydrous sodium sulfate, remove the solvent by rotary evaporation, and dry under vacuum to obtain intermediate (3), with a yield of about 37.07 g and a yield of 69%.

[0050] S2. Dissolve 14.381g of intermediate (3) in 60mL of methanol and stir at 15℃ for 10min. After dissolution, add 0.4g of sodium tungstate dihydrate, followed by slow dropwise addition of 4mL of 30% hydrogen peroxide aqueous solution. After heating to 25℃ and continuing the reaction for 24h, a light pink solid appears in the system. After continuing the reaction for 5h, collect the solid product by vacuum filtration and dry it in a vacuum drying oven at 35℃ for 8h to obtain intermediate (4), with a yield of about 10.78g and a yield of 71%.

[0051] S3. In a 1000mL three-necked flask, 6g of intermediate (4) was dissolved in 600mL of methanol at room temperature by sonication. Then, 150mL of cyclohexane, 1.5255g of FeSO4, 15mL of water, 0.9mL of glacial acetic acid, and 2.625g of TBHP were added sequentially. The mixture was stirred at 55℃ for 0.5h. The temperature of the mixture was raised to 80℃, and 51.3mL of 30% hydrogen peroxide was slowly added dropwise to the reaction flask over 3h. After the addition was completed, the reaction was continued for 15h. After cooling naturally to room temperature, the solid impurities were filtered off. Dichloromethane and water were added to the reaction solution for extraction. The organic phase was collected, and the crude product was obtained by rotary evaporation and vacuum drying. The crude product was purified by column chromatography to obtain intermediate (5), with a yield of about 4.08g and a yield of 53%.

[0052] S4. Dissolve 11.72 g of intermediate (5) and 0.6 g of ethylenediamine in 200 mL of xylene and 2.12 g of 30% NaOH aqueous solution, and react at 110 °C for 12 h under nitrogen protection. Extract, collect the organic phase, and then wash the organic phase three times with 50 mL of water. Dry with anhydrous sodium sulfate to obtain the crude product. Further purify the crude product by column chromatography to obtain a dumbbell-shaped bifunctional hindered amine light stabilizer with a yield of approximately 3.9 g and a yield of 27%.

[0053] Example 4: A method for preparing a dumbbell-type bifunctional hindered amine light stabilizer provided by the present invention includes the following steps: S1, 18.44 g of 2,4,6-trichloro-1,3,5-triazine is dissolved in 200 mL of ethyl acetate. Under an ice-water bath, 42.42 g of N-n-butyl-2,2,6,6-tetramethyl-4-piperidinamine is slowly added and reacted for 2 h. Then, 20 mL of 30% NaOH aqueous solution is added dropwise as a catalyst, and the reaction is continued at 100 °C for 14 h. After the reaction is complete, 200 mL of water is added for extraction three times to separate the organic phase. The organic phase is dried over anhydrous sodium sulfate, the solvent is removed by rotary evaporation, and the intermediate (3) is obtained after vacuum drying. The yield is about 45.13 g, with a yield of 84%.

[0054] S2. Dissolve 14.381g of intermediate (3) in 60mL of methanol and stir at 15℃ for 10min. After dissolution, add 0.4g of sodium tungstate dihydrate, followed by slowly adding 3mL of 30% hydrogen peroxide aqueous solution. After heating to 25℃ and continuing the reaction for 24h, a light pink solid appears in the system. After continuing the reaction for 10h, collect the solid product by vacuum filtration and dry it in a vacuum drying oven at 35℃ for 8h to obtain intermediate (4), with a yield of about 11.99g and a yield of 79%.

[0055] S3. In a 1000mL three-necked flask, 6g of intermediate (4) was dissolved in 600mL of methanol at room temperature by sonication. Then, 200mL of cyclohexane, 1.5255g of FeSO4, 15mL of water, 0.9mL of glacial acetic acid, and 2.625g of TBHP were added sequentially. The mixture was stirred at 55℃ for 0.5h. The temperature of the mixture was raised to 65℃, and 51.3mL of 30% hydrogen peroxide was slowly added dropwise to the reaction flask over 3h. After the addition was completed, the reaction was continued for 15h. After cooling naturally to room temperature, the solid impurities were filtered off. Dichloromethane and water were added to the reaction solution for extraction. The organic phase was collected, and the crude product was obtained by rotary evaporation and vacuum drying. The crude product was purified by column chromatography to obtain intermediate (5), with a yield of about 4.16g and a yield of 54%.

[0056] S4. Dissolve 11.72 g of intermediate (5) and 1.08 g of p-phenylenediamine in 200 mL of toluene and 4.45 g of 30% NaHCO3 aqueous solution. React at 110 °C for 12 h under nitrogen protection. Extract the organic phase, collect it, and then wash it three times with 50 mL of water. Dry the phase with anhydrous sodium sulfate to obtain the crude product. Further purify the crude product by column chromatography to obtain a dumbbell-shaped bifunctional hindered amine light stabilizer with a yield of approximately 5.3 g (36%).

[0057] Of the above embodiments, Example 1 is the preferred embodiment. Example 1, by optimizing the reaction medium, catalyst type, and reaction temperature, significantly improved the purity of the intermediates and final products while maintaining leading yields at each step, providing a material basis for its application as a light stabilizer. The controllability of its reaction conditions and the stability of its product quality give it greater practical value in industrial-scale production.

[0058] Application method:

[0059] The dumbbell-shaped bifunctional hindered amine light stabilizer prepared in Example 1 was used in the preparation of PE materials to produce PE films. The effect of the dumbbell-shaped bifunctional hindered amine light stabilizer prepared in Example 1 on the mechanical properties of the PE materials after artificial climate aging was tested. The amount of the dumbbell-shaped bifunctional hindered amine light stabilizer added in the preparation of the PE film was 0.3% of the total PE film mass.

[0060] The 1H NMR spectrum of the dumbbell-shaped bifunctional hindered amine light stabilizer synthesized in Example 1 is as follows: Figure 1 As shown, the results are as follows: 1 HNMR (600MHz, CDCl3) δ5.05 (d, J = 58.6Hz, 5H), 3.61 (s, 8H), 3.36-3.07 (m, 11H), 2.04 (s, 8H), 1.84-0.60 (m, 122H).

[0061] The mass spectra of the dumbbell-shaped bifunctional hindered amine light stabilizer synthesized in Example 1 are as follows: Figure 2 As shown, MS(ESI), m / z: 1452.2557[M+H]+.

[0062] The mechanical properties of the dumbbell-shaped bifunctional hindered amine light stabilizer-doped PE film synthesized in Example 1 at different aging times are shown in the following figures. Figure 3 As shown, from Figure 3(a) It can be seen that the PE film with 0.3% of the synthesized dumbbell-shaped bifunctional hindered amine light stabilizer has a higher tensile strength retention rate than the PE film with Tinuvin 152, especially after long-term light exposure, its tensile strength retention advantage is more obvious, indicating that it has a stronger ability to protect the material's tensile properties from photoaging. Figure 3 (b) It can be seen that the PE film with 0.3% of the synthesized dumbbell-shaped bifunctional hindered amine light stabilizer exhibits a better elongation at break retention rate throughout the entire light exposure cycle than the PE film with Tinuvin 152, demonstrating its ability to more effectively delay the toughness degradation caused by photoaging in maintaining material toughness. The results indicate that, compared to the light stabilizer Tinuvin 152, the addition of the dumbbell-shaped bifunctional hindered amine light stabilizer synthesized in Example 1 can significantly improve the anti-aging effect of the PE film.

[0063] The above embodiments are merely preferred technical solutions of the present invention and should not be regarded as limitations on the present invention. The scope of protection of the present invention should be the technical solution described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A method for preparing a dumbbell-shaped bifunctional hindered amine light stabilizer, characterized in that: Includes the following steps: S1. Using N-n-butyl-2,2,6,6-tetramethyl-4-piperidinamine (1) and 2,4,6-trichloro-1,3,5-triazine (2) as raw materials, an intermediate (3) was synthesized by nucleophilic substitution. S2. Add hydrogen peroxide aqueous solution to intermediate (3), add reaction solvent and catalyst, and obtain intermediate (4) through oxidation reaction; S3. Using intermediate (4) and cyclohexane as raw materials, add reaction solvent, oxidant and catalyst, and obtain intermediate (5) through nucleophilic substitution reaction; S4. The intermediate (5) and an aliphatic or aromatic diamine are coupled under N2 protection to obtain a dumbbell-shaped bifunctional hindered amine light stabilizer.

2. The method for preparing a dumbbell-shaped bifunctional hindered amine light stabilizer according to claim 1, characterized in that: In S1, the molar ratio of N-n-butyl-2,2,6,6-tetramethyl-4-piperidinamine (1) and 2,4,6-trichloro-1,3,5-triazine (2) is 2:

1.

3. The method for preparing a dumbbell-shaped bifunctional hindered amine light stabilizer according to claim 2, characterized in that: In S2, the molar ratio of 2-chloro-4,6-di-[N-n-butyl-N-(2,2,6,6-tetramethyl-4-piperidinyl)amino]-1,3,5-triazine (3) to 30% hydrogen peroxide aqueous solution is 1:1.1-1.

5.

4. The method for preparing a dumbbell-shaped bifunctional hindered amine light stabilizer according to claim 1, characterized in that: In step S3, the molar ratio of intermediate (4) to cyclohexane is 1:2-2.

4.

5. The method for preparing a dumbbell-shaped bifunctional hindered amine light stabilizer according to claim 1, characterized in that: In step S4, the molar ratio of intermediate (5) to aliphatic or aromatic diamine is 2-2.5:

1.

6. The method for preparing a dumbbell-shaped bifunctional hindered amine light stabilizer according to claim 1, characterized in that: The coupling reaction in step S4 is specifically as follows: the intermediate (5) and the aliphatic or aromatic diamine are dissolved in the reaction solvent, a catalyst is added, and the mixture is heated to 110°C and reacted for 12 h under nitrogen protection. Extraction was performed, and the organic phase was collected. The organic phase was then washed several times with water and dried with anhydrous sodium sulfate to obtain the crude product. The crude product was further purified by column chromatography to obtain a dumbbell-shaped bifunctional hindered amine light stabilizer.

7. The method for preparing a dumbbell-shaped bifunctional hindered amine light stabilizer according to claim 1, characterized in that: In step S4: the reaction solvent is one of toluene, xylene and benzene, and the catalyst is one of NaOH aqueous solution or NaHCO3 aqueous solution with a mass concentration of 10-30%.

8. The dumbbell-shaped bifunctional hindered amine light stabilizer prepared by the method according to claim 1.

9. The application of the dumbbell-shaped bifunctional hindered amine light stabilizer according to claim 8 in PE.

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