Preparation method of efficient light stabilizer

Abstract

The invention discloses a preparation method of a high-efficiency light stabilizer, the high-efficiency light stabilizer is carbonic acid-2, 2, 6, 6-tetramethyl-1-(undecyloxy)-4-piperidinol phenolic ester, and the preparation method comprises the following steps: taking a piperidinol intermediate 4-hydroxy-1-undecyloxy-2, 2, 6, 6-tetramethylpiperidine and slightly excessive triphosgene as raw materials, taking MgCl2 as a catalyst, and reacting at the temperature of 60-80 DEG C for 1-2 hours to obtain the high-efficiency light stabilizer, the high-efficiency light stabilizer is carbonic acid-2, 2, 6, 6-tetramethyl-1-(undecyloxy)-4-piperidinol phenolic ester. The method comprises the following steps of: reacting 2, 2, 6, 6-tetramethyl-1-(undecyloxy)-4-piperidine phenol ester serving as a raw material in a reaction solvent under the protection of nitrogen, and performing post-treatment after the reaction is finished to obtain a target product carbonic acid-2, 2, 6, 6-tetramethyl-1-(undecyloxy)-4-piperidine phenol ester, and the reaction formula is imgabs0 #. The method for synthesizing the carbonic acid-2, 2, 6, 6-tetramethyl-1-(undecyloxy)-4-piperidinol ester has the advantages of being low in catalyst dosage, low in reaction temperature, short in needed reaction time and the like, the yield and the purity of the target product are high, and industrial production of the carbonic acid-2, 2, 6, 6-tetramethyl-1-(undecyloxy)-4-piperidinol ester is facilitated.

Description

Technical Field

[0001] The invention relates to a method for preparing a high-efficiency light stabilizer. Background Art

[0002] Generally speaking, the light stabilizers added and used in polymer materials are divided into three categories. The first category is light shielding agents, such as the commonly used zinc oxide; the second category is ultraviolet absorbers, such as the commonly used benzotriazole ultraviolet absorber UV326; the third category is hindered amine light stabilizers, such as the commonly used dimethyl piperidine light stabilizer UV119.

[0003] Among them, hindered amine light stabilizers are a type of highly efficient light stabilizers, which often have a very significant promoting effect on the photostabilization of polymer materials. They achieve the purpose of photostabilization of polymers by capturing free radicals produced during the photooxidation and degradation of polymers. They are also common and highly efficient light stabilizers in coatings.

[0004]

[0005] Among the structural characteristics of the above-mentioned hindered amine light stabilizers, the N-OR type light stabilizer has the weakest alkalinity and the lowest reaction activity with acidic substances, and can be used as a good acid-resistant light stabilizer.

[0006] According to the relevant patent CN1926107B, ADEKA Co., Ltd. has developed a high-performance hindered amine N-OR type light stabilizer, and its related general structure is as follows:

[0007]

[0008] Structure of hindered amine N-OR type light stabilizer developed by ADEKA Co., Ltd. (CN1926107B)

[0009] According to the relevant patent CN1926107B, among the typical compound structures given, the structures of 1#, 2#, 3#, and 4# are similar and have only one highly active group - carbonyl (C=O). Compared with compounds with two carbonyl groups, they have better chemical stability. Among them, the compound 1# structure, in particular, has a moderate molecular weight compared with the structures of compound 2#, compound 3#, and compound 4#, and has high efficiency in promoting photostability, excellent resistance to precipitation, and excellent processing thermal stability; while the structures of compound 2# and compound 3# have too small molecular weight, and their resistance to precipitation and processing thermal stability are not as good as those of compound 1# structure; the molecular weight of compound 4# structure is too large, and under the same addition amount, the effective group part (tetramethylpiperidine) of promoting photostability of compound 4# structure accounts for only 80% of the effective group part (tetramethylpiperidine) of promoting photostability of compound 1# structure, so the photostability of compound 4# structure is not as good as that of compound 1# structure.

[0010] According to the relevant patent CN1926107B, the 1# structure of the hindered amine N-OR type light stabilizer structure shown in its general structure, di(1-undecyloxy-2,2,6,6-tetramethylpiperidin-4-yl) carbonate, has excellent light stability and acid resistance, but its synthesis method is inefficient, especially the second step reaction ester exchange coupling reaction, as follows:

[0011]

[0012] Synthesis method of hindered amine N-OR type light stabilizer developed by ADEKA Co., Ltd. (ester exchange coupling reaction)

[0013] According to Example 1 of CN1926107B, the yield of the transesterification coupling reaction for synthesizing compound 1# structure is only 55.5%, which is very low and has a very obvious disadvantage for realizing industrial synthesis.

[0014] The compound 1# structure mentioned above has a chemical name of di(1-undecyloxy-2,2,6,6-tetramethylpiperidin-4-yl) carbonate, an alias of 2,2,6,6-tetramethyl-1-(undecyloxy)-4-piperidinol carbonate, a CAS number of 705257-84-7, and an appearance of light yellow liquid. According to public information of ADEKA Co., Ltd., it is the main component of ADEKA Co., Ltd.'s product LA-81. Summary of the invention

[0015] In view of the above technical problems existing in the prior art, the object of the present invention is to provide a method for preparing a high-efficiency light stabilizer, specifically to provide a new and efficient synthesis method for industrial production of 2,2,6,6-tetramethyl-1-(undedecyloxy)-4-piperidinol carbonate (CAS No. 705257-84-7), which is conducive to providing an industrial product of 2,2,6,6-tetramethyl-1-(undedecyloxy)-4-piperidinol carbonate (CAS No. 705257-84-7) with high synthesis yield and high purity.

[0016] The researchers of the present invention have conducted in-depth research to solve the above problems and found a new process for synthesizing 2,2,6,6-tetramethyl-1-(undecyloxy)-4-piperidinol carbonate (CAS No. 705257-84-7). The reaction formula is as follows:

[0017]

[0018] Triphosgene (CAS 32315-10-9) is used to replace diphenyl carbonate (CAS102-09-0) to fully react with piperidinol "4-hydroxy-1-undedecyloxy-2,2,6,6-tetramethylpiperidine", so that high synthesis yield and high purity carbonic acid-2,2,6,6-tetramethyl-1-(undedecyloxy)-4-piperidinol ester (CAS No. 705257-84-7) is obtained by using triphosgene and matching and setting the most suitable process conditions, thereby completing the present invention.

[0019] The technical solution adopted by the present invention is as follows:

[0020] A method for preparing a high-efficiency light stabilizer, wherein the high-efficiency light stabilizer is 2,2,6,6-tetramethyl-1-(undecanyloxy)-4-piperidinol carbonate. The method for preparing the high-efficiency light stabilizer comprises the following steps: using a piperidinol intermediate 4-hydroxy-1-undecanyloxy-2,2,6,6-tetramethylpiperidine and a slightly excess amount of triphosgene as raw materials, and using MgCl2 as a catalyst, reacting in a reaction solvent under nitrogen protection, and obtaining the target product 2,2,6,6-tetramethyl-1-(undecanyloxy)-4-piperidinol carbonate through post-treatment after the reaction is completed.

[0021] Furthermore, theoretically, 6 piperidinols react with 1 triphosgene molecule. In the reaction of the present invention, triphosgene is slightly excessive, and the molar ratio of the 4-hydroxy-1-undecanyloxy-2,2,6,6-tetramethylpiperidine to triphosgene is 1:0.168-0.2, preferably 1:0.170-0.175.

[0022] Furthermore, the molar ratio of the MgCl2 catalyst to 4-hydroxy-1-undecyloxy-2,2,6,6-tetramethylpiperidine is 0.02-0.04:1, preferably 0.03-0.035:1.

[0023] Furthermore, the reaction solvent is toluene, xylene or heptane, and the mass concentration of 4-hydroxy-1-undecyloxy-2,2,6,6-tetramethylpiperidine dispersed in the reaction solvent is 20-50%, preferably 30-40%.

[0024] Furthermore, the specific process of the reaction is: under nitrogen protection, 4-hydroxy-1-undecyloxy-2,2,6,6-tetramethylpiperidine and MgCl2 catalyst are added to the reaction solvent, stirred, and triphosgene as a raw material is added at a uniform speed using a powder quantitative feeder at normal temperature and pressure, and the addition speed is adjusted in real time so that the reaction temperature does not exceed 40°C; after the addition of triphosgene is completed, the reaction system is heated to less than 70°C for reaction for 1.5-3h, and then heated to 90°C±5°C for constant temperature reaction until the reaction is complete, thereby terminating the reaction.

[0025] Furthermore, after the addition of triphosgene is completed, the reaction system is subjected to a temperature increase reaction in three stages, specifically: first, the temperature is increased to 50°C±2°C, and the reaction is carried out at a constant temperature for 0.8-1.2h; then, the temperature is increased to 70°C±2°C, and the reaction is carried out at a constant temperature for 0.8-1.2h; and finally, the temperature is increased to 90°C±2°C, and the reaction is carried out at a constant temperature until completion.

[0026] The present invention controls the reaction process to gradually increase the temperature of the reaction. On the one hand, in the initial stage of the reaction, it avoids the problem that a large amount of HCl gas is easily boiled due to the high reaction temperature. On the other hand, it also avoids the problem of too fast reaction, more side reactions and low product yield. However, as the reaction proceeds, the concentration of the reactants will decrease, and the mutual reaction activity between them will decrease. Then, gradually increasing the reaction temperature is conducive to stabilizing the reaction rate, so that the reaction is steadily advanced under the premise of safety and controllability, which is conducive to industrial implementation.

[0027] Furthermore, the post-treatment step is: after the reaction system is cooled to room temperature, diatomaceous earth powder is added and stirred for 10-30 minutes, filtered, and then the filtrate is subjected to reduced pressure distillation to completely remove the solvent and other low-boiling impurities to obtain the target product, 2,2,6,6-tetramethyl-1-(undecanyloxy)-4-piperidinol carbonate.

[0028] Furthermore, the added mass of diatomite powder is 10-30% of the mass of triphosgene raw material. The diatomite component itself has a certain amount of moisture, and a trace amount of triphosgene can react with a trace amount of water during the post-treatment process to generate hydrogen chloride and carbonic acid. The present invention adds diatomite during the post-treatment process, which can react with the unreacted trace amount of triphosgene to achieve the technical effect of terminating the reaction and harmlessly rendering the triphosgene, reducing the difficulty of purifying the target product carbonic acid-2,2,6,6-tetramethyl-1-(undecanyloxy)-4-piperidinol ester, and obtaining a high-purity target compound.

[0029] The triphosgene used as a raw material in the present invention has a molecular formula of CO(OCCl3)2, a CAS number of 32315-10-9, is a white crystal at room temperature, has a high melting and boiling point, low volatility, and low toxicity. In industrial applications, it is only treated as a general toxic substance and can be used safely in industrial production. Although phosgene and diphosgene with similar reactivity are widely used in medicine, pesticides, organic intermediate synthesis and polymer material synthesis, phosgene is a gas and diphosgene is a liquid, both of which have low boiling points, high volatility, and are highly toxic. They are very dangerous chemicals and their use has been banned or restricted in many countries.

[0030]

[0031] The piperidinol "4-hydroxy-1-undecyloxy-2,2,6,6-tetramethylpiperidine" used as a raw material in the present invention has a structure as shown above and can be synthesized using, but not limited to, the method suggested in Example 1 of patent CN1926107B.

[0032] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: the method for synthesizing 2,2,6,6-tetramethyl-1-(undecanyloxy)-4-piperidinol carbonate has the advantages of low catalyst dosage, low reaction temperature, short required reaction time, etc., and the yield and purity of the target product are high, which is conducive to the industrial production of 2,2,6,6-tetramethyl-1-(undecanyloxy)-4-piperidinol carbonate. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is the H of 2,2,6,6-tetramethyl-1-(undecyloxy)-4-piperidinol carbonate synthesized in Example 1 1 (CDCl3) spectrum;

[0034] Figure 2 The C of 2,2,6,6-tetramethyl-1-(undecyloxy)-4-piperidinol carbonate synthesized in Example 1 13 (CDCl3) spectrum;

[0035] Figure 3 This is the FT-IR spectrum of 2,2,6,6-tetramethyl-1-(undecyoxy)-4-piperidinol carbonate synthesized in Example 1. DETAILED DESCRIPTION

[0036] The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0037] Diatomaceous earth, whose chemical composition is mainly SiO2 (i.e. SiO2 accounts for more than 80%), can be expressed as SiO2·nH2O.

[0038] Embodiment 1:

[0039] A 3000 ml glass double-layer reactor was equipped with a stirrer, a nitrogen inlet pipe, a thermometer, an acid gas absorber (10% NaOH aqueous solution), a distillation tube and a stopcock (for sampling). A water quantitative receiver and a cooling tube were installed at the front end of the distillation tube, and a powder quantitative feeder (which can maintain a nitrogen atmosphere) was set up. The above device was used as a reaction device, and the experimental steps for the reaction were as follows:

[0040] 1) After sufficient nitrogen replacement in the above reactor, 4-hydroxy-1-undecyloxy-2,2,6,6-tetramethylpiperidine (327.6 g) as a raw material, toluene (500.0 g) as a solvent, and MgCl2 (3.0 g) as a catalyst were added under continuous nitrogen flow. Triphosgene (50.4 g) as a raw material was added at a uniform rate using a powder quantitative feeder at normal temperature and pressure, and the addition rate was adjusted in real time so that the reaction temperature did not exceed 40°C.

[0041] 2) After the addition is completed, the system temperature is raised to 50°C and the reaction is carried out for 1 hour. The system temperature is then raised to 70°C and the reaction is carried out for 1 hour. Thereafter, the system temperature is raised to 90°C and the reaction is carried out for more than 1 hour until the residual amount of the raw material 4-hydroxy-1-undecyloxy-2,2,6,6-tetramethylpiperidine is less than 1%, and the reaction is terminated.

[0042] 3) After the reaction system is cooled to room temperature, diatomaceous earth powder (10 g) is added and stirred for 20 minutes, filtered thoroughly, and then the filtrate is distilled under reduced pressure to completely remove the solvent and other low-boiling impurities, thereby producing the target product, 2,2,6,6-tetramethyl-1-(undecanyloxy)-4-piperidinol carbonate (CAS No. 705257-84-7), with a yield of 94% and a purity of 99.9%, which is a transparent colorless liquid.

[0043] The reaction time of Example 1 at 90° C. is 3 h, and the total reaction time is 5 h.

[0044] The identification of the synthesized 2,2,6,6-tetramethyl-1-(undecyoxy)-4-piperidinol carbonate (CAS No. 705257-84-7) was performed using nuclear magnetic resonance and infrared. The identification results are shown below.

[0045] The H of the synthesized 2,2,6,6-tetramethyl-1-(undecyloxy)-4-piperidinol carbonate 1 (CDCl3) spectrum is Figure 1 , H of 2,2,6,6-tetramethyl-1-(undecyloxy)-4-piperidinol carbonate as the main component 1 (CDCl3) chemical shifts are δ0.82-0.92ppm(6H),1.13-1.12ppm(24H),1.22-1.34ppm(32H),1.44-1.53ppm(4H),1.54-1.63ppm(4H),1.82-1.94ppm(4H),3.65-3.76ppm(4H),4.78-4.88ppm(2H).

[0046] The C of the synthesized 2,2,6,6-tetramethyl-1-(undecyloxy)-4-piperidinol carbonate 13 (CDCl3) spectrum is Figure 2 , C of 2,2,6,6-tetramethyl-1-(undecyloxy)-4-piperidinol carbonate as the main component 13 (CDCl3) chemical shifts are 154.32ppm, 77.35ppm, 77.03ppm, 76.71ppm, 70.81ppm, 59.91ppm, 43.97ppm, 33.06ppm, 31.92ppm, 29.70ppm, 29.63ppm, 29.59ppm, 29.35ppm, 28.69ppm, 26.42ppm, 27.70ppm, 20.81ppm, 14.31ppm.

[0047] The infrared spectrum of the synthesized 2,2,6,6-tetramethyl-1-(undecyloxy)-4-piperidinol carbonate is Figure 3 , IR spectrum of 2,2,6,6-tetramethyl-1-(undecyloxy)-4-piperidinol carbonate as the main component: 1000cm -1 ,1190cm -1 ,1240cm -1 ,1270cm -1 ,1310cm -1 ,1360cm -1 ,1380cm -1 ,1450cm -1 ,1740cm -1 ,2800-3050cm -1 .

[0048] Example 2

[0049] The experimental steps of Example 2 are repeated in Example 1, with the only difference being that "toluene as a solvent is replaced with an equal mass of xylene" and the other conditions remain unchanged, and finally 2,2,6,6-tetramethyl-1-(undecanyloxy)-4-piperidinol carbonate as the target product is produced.

[0050] The reaction time of Example 2 at 90°C is 4 hours, and the total reaction time is 6 hours.

[0051] Example 3

[0052] The experimental steps of Example 3 are repeated as in Example 1, except that "toluene as a solvent is replaced with an equal mass of heptane", and the other conditions remain unchanged, and finally 2,2,6,6-tetramethyl-1-(undecanyloxy)-4-piperidinol carbonate as the target product is produced.

[0053] The reaction time of Example 3 at 90°C is 2 hours, and the total reaction time is 4 hours.

[0054] Example 4

[0055] The experimental steps of Example 4 are repeated in Example 1, with the only difference being that "after the addition in step 2) is completed, the system temperature is raised to 50°C and the reaction is carried out for 2 hours, and then the system temperature is raised to 90°C and the reaction is carried out for more than 1 hour until the residual amount of 4-hydroxy-1-undecyloxy-2,2,6,6-tetramethylpiperidine of the raw material is less than 1%, and the reaction is terminated", and the other conditions remain unchanged, and finally 2,2,6,6-tetramethyl-1-(undecyloxy)-4-piperidinol carbonate as the target product is produced.

[0056] Example 5

[0057] The experimental steps of Example 5 are repeated in Example 1, with the only difference being that "after the addition in step 2) is completed, the system temperature is raised to 70°C and the reaction is carried out for 2 hours, and then the system temperature is raised to 90°C and the reaction is carried out for more than 1 hour until the residual amount of 4-hydroxy-1-undecyloxy-2,2,6,6-tetramethylpiperidine of the raw material is less than 1%, and the reaction is terminated", and the other conditions remain unchanged, and finally 2,2,6,6-tetramethyl-1-(undecyloxy)-4-piperidinol carbonate as the target product is produced.

[0058] Comparative Example 1:

[0059] The experimental steps of Comparative Example 1 were repeated in Example 1, except that "after the addition in step 2) was completed, the system temperature was raised to 60° C. for constant temperature reaction", and the other conditions remained unchanged, and finally 2,2,6,6-tetramethyl-1-(undecanyloxy)-4-piperidinol carbonate as the target product was produced.

[0060] In Comparative Example 1, the reaction was carried out at a constant temperature of 60° C. for 13 h, but the raw material 4-hydroxy-1-undecyloxy-2,2,6,6-tetramethylpiperidine was not completely reacted.

[0061] Comparative Example 2:

[0062] The experimental steps of Comparative Example 2 are repeated in Example 1, except that "after the addition in step 2) is completed, the system temperature is raised to 70° C. for constant temperature reaction", and the other conditions remain unchanged, and finally 2,2,6,6-tetramethyl-1-(undecanyloxy)-4-piperidinol carbonate as the target product is produced.

[0063] In Comparative Example 2, the reaction was carried out at a constant temperature of 70° C. for 12 h, but the raw material 4-hydroxy-1-undecyloxy-2,2,6,6-tetramethylpiperidine was not completely reacted.

[0064] Comparative Example 3:

[0065] The experimental steps of Comparative Example 3 are repeated in Example 1, with the only difference being that "after the addition in step 2) is completed, the system temperature is raised to 120° C. for constant temperature reaction until the residual amount of 4-hydroxy-1-undecyloxy-2,2,6,6-tetramethylpiperidine of the raw material is less than 1%, and the reaction is terminated", and the other conditions remain unchanged, and finally 2,2,6,6-tetramethyl-1-(undecyloxy)-4-piperidinol carbonate as the target product is produced.

[0066] The reaction time of comparative example 3 at a constant temperature of 120° C. is 3 h.

[0067] Comparative Example 4:

[0068] The experimental steps of Comparative Example 4 are repeated in Example 1, with the only difference being that "after the addition in step 2) is completed, the system temperature is raised to 90° C. for constant temperature reaction until the residual amount of 4-hydroxy-1-undecyloxy-2,2,6,6-tetramethylpiperidine of the raw material is less than 1%, and the reaction is terminated", and the other conditions remain unchanged, and finally 2,2,6,6-tetramethyl-1-(undecyloxy)-4-piperidinol carbonate as the target product is produced.

[0069] The reaction time of comparative example 4 at a constant temperature of 120° C. is 4 h.

[0070] The experimental results of Examples 1-3 and Comparative Examples 1-4 are summarized in Table 1.

[0071] Table 1. Effect of reaction temperature on the yield and purity of the synthesized products

[0072]

[0073] The following conclusions can be drawn from the experimental results in Table 1:

[0074] 1) Comparing the experimental results of Comparative Examples 1-4 with those of Examples 1 and 4-5, it can be seen that the multi-step reaction temperature of the "one-pot reaction" (i.e., staged heating) has a significant effect on the product yield and purity. For the reaction of the present invention, controlling the staged heating conditions can shorten the reaction time and prepare high-yield and high-purity products.

[0075] 2) Compared with the experimental results of Examples 1-3, good reaction effects can be achieved when toluene, xylene and heptane are used as reaction solvents.

[0076] 3) Comparing the experimental results of Example 1 with those of Examples 4-5, it can be seen that the experimental effect of the three-stage temperature increase reaction is better, and a relatively high yield product can be obtained in a relatively short time.

[0077] The contents described in this specification are merely an enumeration of implementation forms of the inventive concept, and the protection scope of the present invention should not be regarded as being limited to the specific forms described in the embodiments.

Claims

1. A method for preparing a high-efficiency light stabilizer, characterized in that The high-efficiency light stabilizer is 2,2,6,6-tetramethyl-1-(undecyloxy)-4-piperidinol carbonate, and the preparation method thereof is as follows: using the piperidinol intermediate 4-hydroxy-1-undecyloxy-2,2,6,6-tetramethylpiperidine and a slightly excess amount of triphosgene as raw materials, and MgCl2 as a catalyst, reacting in a reaction solvent under nitrogen protection, and after the reaction is completed, post-treatment is performed to obtain the target product 2,2,6,6-tetramethyl-1-(undecyloxy)-4-piperidinol carbonate, and the reaction formula is as follows:

2. The method for preparing a high-efficiency light stabilizer according to claim 1, characterized in that The molar ratio of the 4-hydroxy-1-undecyloxy-2,2,6,6-tetramethylpiperidine to triphosgene is 1:0.168-0.

25.

3. The method for preparing a high-efficiency light stabilizer according to claim 2, characterized in that The molar ratio of the 4-hydroxy-1-undecyloxy-2,2,6,6-tetramethylpiperidine to triphosgene is 1:0.170-0.

20.

4. The method for preparing a high-efficiency light stabilizer according to claim 1, characterized in that The molar ratio of the MgCl2 catalyst to 4-hydroxy-1-undecyloxy-2,2,6,6-tetramethylpiperidine is 0.02-0.040:

1.

5. The method for preparing a high-efficiency light stabilizer according to claim 1, characterized in that The molar ratio of the MgCl2 catalyst to 4-hydroxy-1-undecyloxy-2,2,6,6-tetramethylpiperidine is 0.03-0.035:

1.

6. The method for preparing a high-efficiency light stabilizer according to claim 1, characterized in that The reaction solvent is toluene, xylene or heptane, and the mass concentration of 4-hydroxy-1-undecyloxy-2,2,6,6-tetramethylpiperidine dispersed in the reaction solvent is 20-50%.

7. The method for preparing a high-efficiency light stabilizer according to claim 1, characterized in that The specific process of the reaction is: under nitrogen protection, 4-hydroxy-1-undecyloxy-2,2,6,6-tetramethylpiperidine and MgCl2 catalyst are added to the reaction solvent, stirred, and triphosgene as a raw material is added at a uniform speed using a powder quantitative feeder at normal temperature and pressure, and the addition speed is adjusted in real time so that the reaction temperature does not exceed 40°C; after the addition of triphosgene is completed, the reaction system is heated to less than 70°C for reaction for 1.5-3h, and then the temperature is raised to 90°C±5°C, and the reaction is carried out at a constant temperature until it is complete, and the reaction is terminated.

8. The method for preparing a high-efficiency light stabilizer according to claim 7, characterized in that After the addition of triphosgene is completed, the reaction system is heated in three stages, specifically: first, the temperature is raised to 50°C±2°C, and the reaction is carried out at a constant temperature for 0.8-1.2h; then the temperature is raised to 70°C±2°C, and the reaction is carried out at a constant temperature for 0.8-1.2h; finally, the temperature is raised to 90°C±2°C, and the reaction is carried out at a constant temperature until completion.

9. The method for preparing a high-efficiency light stabilizer according to claim 1, characterized in that The post-treatment step comprises: after the reaction system is cooled to room temperature, diatomaceous earth powder is added and stirred for 10-30 minutes, filtered, and then the filtrate is subjected to reduced pressure distillation to completely remove the solvent and other low-boiling impurities, so as to obtain the target product, 2,2,6,6-tetramethyl-1-(undecanyloxy)-4-piperidinol carbonate.

10. The method for preparing a high-efficiency light stabilizer according to claim 9, characterized in that The added mass of the diatomaceous earth is 10-30% of the mass of the triphosgene raw material.

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