Preparation method of high-efficiency low-alkalinity hindered amine light stabilizer

Abstract

The invention discloses a preparation method of a high-efficiency low-alkalinity hindered amine light stabilizer, belongs to the technical field of new materials, and is used for solving the technical problems that the alkalinity of the hindered amine light stabilizer is too high and the efficiency needs to be further improved in the prior art. The method comprises the following steps: adding a hindered amine type light stabilizer crude product, a modified decolorizing agent, a 20-30wt% hydrogen peroxide solution and absolute ethyl alcohol into a reaction kettle, stirring, raising the temperature of the reaction kettle to 30-40 DEG C, carrying out heat preservation reaction for 1-2 hours, and carrying out post-treatment to obtain the hindered amine type light stabilizer, according to the preparation method of the hindered amine type light stabilizer, the modified decolorizing agent and the modified catalyst are prepared aiming at the hindered amine type light stabilizer, lone pair electrons of nitrogen atoms are more stable due to the annular structure of the hindered amine type light stabilizer, the alkalinity of a system is reduced, and the alkalinity of a product is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of new materials, and in particular to a method for preparing a high-efficiency and low-alkalinity hindered amine light stabilizer. Background Art

[0002] Hindered amine light stabilizers are widely used in light stabilization of plastics and coatings due to their excellent free radical capture ability. Traditional hindered amine light stabilizers are easily inactivated in acidic environments due to their high alkalinity and may cause side effects on sensitive substrates. To solve this problem, high-efficiency and low-alkalinity hindered amine light stabilizers have gradually become a research hotspot.

[0003] First, non-basic groups are introduced through molecular modification to reduce alkalinity while maintaining stability. Second, hindered amine light stabilizer molecules containing low-alkalinity heterocycles are designed to perform better under acidic conditions. In addition, the polymerized hindered amine light stabilizer that is bonded to the polymer chain significantly reduces mobility and reduces the alkalinity problems caused by free amines, thereby improving material performance.

[0004] Prior art CN111303481B discloses an oligomeric hindered amine light stabilizer and a preparation method thereof. The invention provides a mixed low-alkalinity hindered amine light stabilizer, wherein R1 in the structural formula is a C1-C18 straight-chain alkane or a C5-C7 cycloalkane, and the invention overcomes the problems of poor light stability, high volatility, and easy failure of effective groups of hindered amine light stabilizers in the prior art. The prepared product has better ultraviolet and thermal stability, low volatility, and better compatibility with polymer materials.

[0005] However, the above patent content is to prepare a low-alkalinity mixed hindered amine light stabilizer by polymerization, but there are a large number of long-chain structures inside it, and the ability to restrict the lone pair electrons of nitrogen atoms is insufficient, so that the alkalinity of the material needs to be further reduced. In addition, there are a large number of high-temperature and high-pressure preparation processes in the preparation process, so the efficiency of the prepared material needs to be further improved.

[0006] In view of the technical defects in this aspect, a solution is now proposed. Summary of the invention

[0007] The object of the present invention is to provide a method for preparing a high-efficiency and low-alkalinity hindered amine light stabilizer, so as to solve the technical problems in the prior art that the alkalinity of the hindered amine light stabilizer is too high and the efficiency needs to be further improved.

[0008] The purpose of the present invention can be achieved by the following technical scheme: A method for preparing a high-efficiency, low-alkalinity hindered amine light stabilizer comprises the following steps:

[0009] S1, add sebacic acid and modified catalyst into a reactor, after the temperature of the reactor is reduced to 40-50°C, add dithionyl chloride dropwise into the reactor, keep warm for 1-2h, then quickly raise the temperature of the reactor to 70-75°C, keep warm for 10-15min, after the reaction is completed, add chloroform after the temperature of the reactor is reduced to room temperature, and recover the sebacic acid chloride mixture and dithionyl chloride by post-processing;

[0010] The reaction mechanism for preparing sebacoyl chloride is:

[0011] The mass spectrometry analysis data of sebacic acid chloride are m / z: 238.05 (100.0%), 240.05 (64.0%), 239.06(11.1%), 242.05 (10.5%), 241.05 (7.0%), 243.05 (1.1%), 240.06 (1.0%).

[0012] S2, adding the sebacic acid chloride mixture and pentamethylpiperidinol into a reactor, raising the temperature of the reactor to 40-50°C, keeping the temperature for reaction for 2-3 hours, adding methanol into the reactor, keeping the temperature for reaction for 1-2 hours, and post-treating to obtain a crude hindered amine light stabilizer;

[0013] The formula for preparing crude hindered amine light stabilizer is:

[0014] The principle of preparing the crude hindered amine light stabilizer is as follows: under the catalysis of heating conditions, the acyl chloride group of sebacyl chloride and pentamethylpiperidinol react rapidly, and methanol is used to react with the unreacted acyl chloride group to cap the end, and finally the crude hindered amine light stabilizer is prepared.

[0015] S3. Add the crude hindered amine light stabilizer, modified decolorizer, 20-30wt% hydrogen peroxide solution and anhydrous ethanol into a reactor and stir. Raise the temperature of the reactor to 30-40°C, keep the reaction warm for 1-2h, and post-treat to obtain the hindered amine light stabilizer.

[0016] The principle of preparing hindered amine light stabilizers: Under the catalysis of the oxidizing solution hydrogen peroxide, the electron transfer ability of graphene oxide and hydroxylated boron nitride is enhanced, which can more efficiently guide the free radicals generated by the oxidizing reagent to the target pollutants, thereby accelerating the decolorization reaction and finally preparing a hindered amine light stabilizer.

[0017] Furthermore, in step S1, the dosage ratio of sebacic acid, modified catalyst, dithionyl chloride and chloroform is 3-4g:0.3-0.5g:7-8g:16-18g, and the post-treatment recovery operation is as follows: after the reaction is completed, after the temperature of the reactor is lowered to room temperature, chloroform is added dropwise to the reactor, the reaction solution is transferred to a separatory funnel, and the upper layer of liquid is collected after separation, and the lower layer of liquid is transferred to a rotary evaporator, the internal pressure of the rotary evaporator is reduced to 50-100mmHg, the temperature of the rotary evaporator is increased to 30-40°C, and the fractions are collected to obtain dithionyl chloride, which is evaporated until no liquid is extracted to obtain sebacyl chloride, and the sebacyl chloride is transferred to the upper layer of liquid to obtain a sebacyl chloride mixed solution.

[0018] Furthermore, in step S1, the method for preparing the modified catalyst comprises the following steps:

[0019] A1. Disperse the oxidized multilayer graphene and anhydrous ethanol in an ultrasonic instrument and ultrasonicate for 30-40 min at room temperature, add a saturated sodium hydroxide solution and hydroxylated nano-boron nitride to the ultrasonic instrument, continue ultrasonicating for 1-2 h, add N,N-diethylchloroformamide to the ultrasonic instrument, ultrasonicate for 20-30 min, and perform post-treatment to obtain a catalyst precursor;

[0020] The reaction principle for preparing the catalyst precursor is as follows: under the catalysis of ultrasonic and alkaline conditions, the hydroxyl groups on the hydroxylated boron nitride react with active functional groups such as carboxyl and epoxy groups on the surface of the oxidized multilayer graphene, so that the structures of the hydroxylated boron nitride and the oxidized multilayer graphene are tightly combined, and the halogen groups on the N,N-diethylchloroformamide undergo elimination reaction with the hydroxyl groups on the surfaces of the two, and finally the catalyst precursor is prepared.

[0021] A2. Add the catalyst precursor, sodium borohydride and deionized water into a high-pressure reactor, increase the temperature of the reactor to 120-150° C., keep the temperature for 2-4 hours, and post-treat to obtain a modified catalyst.

[0022] Reaction principle for preparing modified catalysts: After reduction by a strong reducing agent, sodium borohydride, the active functional groups on the surface of the catalyst precursor are reduced, and finally a modified catalyst is prepared.

[0023] Furthermore, in step A1, the ultrasonic frequency of the ultrasonic instrument is 20-40kHz, the amount ratio of oxidized multilayer graphene, anhydrous ethanol, saturated sodium hydroxide solution, hydroxylated nano-boron nitride and N,N-diethylchloroformamide is 2-3g:20-25mL:0.3-0.5mL:4-6g:1-2mL, and the post-treatment includes: after the reaction is completed, filtering the reaction liquid to collect the filter cake, washing the filter cake with anhydrous ethanol and deionized water for 3-5 times, and placing the filter cake in a drying oven at a temperature of 60°C and vacuum drying it until the filter cake has a constant weight to obtain a catalyst precursor.

[0024] Furthermore, in step A2, the usage ratio of the catalyst precursor, sodium borohydride and deionized water is 4-5g:1-2g:10-12mL, and the post-treatment includes: after the reaction is completed, the reaction liquid is filtered to collect the filter cake, the filter cake is washed 3-5 times with anhydrous ethanol and deionized water, and the filter cake is placed in a drying oven at a temperature of 60°C and vacuum dried until the filter cake has a constant weight to obtain a modified catalyst.

[0025] Furthermore, in step A1, the method for preparing the oxidized multilayer graphene and hydroxylated nano-boron nitride comprises the following steps:

[0026] B1, adding 98.0wt% concentrated sulfuric acid to a reactor and stirring, adding potassium permanganate powder to the reactor during stirring, stirring at room temperature for 5-10min, raising the temperature of the reactor to 30-45°C and adding multilayer graphene to the reactor, keeping the temperature and stirring for 2-3h, and post-treating to obtain oxidized multilayer graphene;

[0027] The principle of preparing oxidized multilayer graphene: In a concentrated sulfuric acid environment, permanganate is activated to generate a more oxidizing intermediate. The carbon atoms in the multilayer graphene form a hexagonal lattice structure in the form of sp² hybridization, which has high chemical stability. The oxidizing intermediate destroys this stable conjugated structure and introduces oxygen-containing groups such as hydroxyl, epoxy and carboxyl groups on the graphene surface through oxidation, and finally oxidized multilayer graphene is prepared.

[0028] B2. Add nano boron nitride powder, sodium hydroxide and deionized water into a high-pressure reactor, increase the temperature of the high-pressure reactor to 120-150° C., keep the temperature for 12-16 hours, and perform post-treatment to obtain hydroxylated nano boron nitride.

[0029] The principle of preparing hydroxylated boron nitride: Under high temperature, high pressure and strong alkaline catalysis, the strongly nucleophilic hydroxyl group destroys part of the boron nitrogen surface structure, exposing the boron atoms. The exposed boron atoms are easy to react with hydroxyl groups to form boron hydroxyl groups, and finally hydroxylated nano boron nitride is prepared.

[0030] Furthermore, in step B1, the stirring rate of the reactor is 80-120rpm, the usage ratio of 98.0wt% concentrated sulfuric acid, potassium permanganate powder and multilayer graphene is 45-50mL:6-8g:1-2g, and the post-treatment includes: after the reaction is completed, the reaction liquid is filtered to collect the filter cake, the filter cake is washed 3-5 times with anhydrous ethanol and deionized water, and the filter cake is placed in a drying oven at a temperature of 60°C and vacuum dried until the filter cake has a constant weight to obtain oxidized multilayer graphene.

[0031] Furthermore, in step B2, the dosage ratio of nano-boron nitride powder, sodium hydroxide and deionized water is 5-6g:1-2g:20-25mL, and the post-treatment includes: after the reaction is completed, the reaction liquid is filtered to collect the filter cake, the filter cake is washed with anhydrous ethanol and deionized water for 3-5 times, and the filter cake is placed in a drying oven at a temperature of 60°C and vacuum dried until the filter cake has a constant weight to obtain hydroxylated nano-boron nitride.

[0032] Furthermore, in step S2, the dosage ratio of the sebacic acid chloride mixture, pentamethylpiperidinol, and methanol is 10-12g:2-3g:0.1-0.3g, and the post-treatment includes: after the reaction is completed, the temperature of the reactor is lowered to room temperature, the reaction solution is transferred to a rotary evaporator with a water bath temperature of 40-50°C, and the solvent is evaporated under reduced pressure to obtain a crude hindered amine light stabilizer.

[0033] Furthermore, in step S3, the amount ratio of the crude hindered amine light stabilizer, the modified decolorizing agent, the 20-30wt% hydrogen peroxide solution and the anhydrous ethanol is 8-10g:2-3g:5-8mL:30-40mL, the modified decolorizing agent is obtained by mixing oxidized multilayer graphene and hydroxylated nano-boron nitride in a mass ratio of 1-2g:1g, and the post-treatment includes: after the reaction is completed, after the temperature of the reaction liquid is lowered to room temperature, the reaction liquid is filtered to collect the filtrate, the filtrate is transferred to a rotary evaporator with a water bath temperature of 40-50°C, and the solvent is evaporated under reduced pressure to obtain the hindered amine light stabilizer.

[0034] The present invention has the following beneficial effects:

[0035] 1. The present invention is to prepare oxidized multilayer graphene and hydroxylated nano boron nitride as modified decolorizing agents for decolorization treatment, and to modify hydroxylated nano boron nitride on the surface of oxidized multilayer graphene as a matrix to make its structure more stable, and finally to graft catalytic segments on its surface to obtain catalytic segments, so that the reaction is more efficient, and the ring structure makes the lone pair electrons of the nitrogen atom more stable, thereby reducing the alkalinity of the system;

[0036] In the process of preparing the product, a solution-free method is selected to make the reactants have a higher local concentration, improve the reaction rate and yield, and avoid the problem of solvent residue. The product is usually purer. After further extraction with chloroform, direct contact of sebacyl chloride with air is avoided, making the product purer. In addition, the unreacted thionyl chloride after extraction contains a trace amount of sebacyl chloride, which is conducive to the recovery of thionyl chloride.

[0037] 2. After the oxidized multilayer graphene is prepared by the present invention, hydroxylated nano-boron nitride is grafted on the surface to stabilize its structure. After the modified catalyst is prepared by further modification, the porous structure of the modified catalyst is dispersed in the reaction system. In addition to providing a larger contact area for the reactants to make the reaction more efficient, a large number of surfaces and pores are provided. The gas generated by the reaction can diffuse into the pores more quickly and then be released to the liquid surface, thereby reducing the retention of the gas in the liquid phase and improving the gas transfer efficiency of the reaction system. In addition, the surface of the porous material can be used as the nucleation point of the bubble. The porous material can disturb the gas-liquid interface and reduce the release resistance of the gas, so that the generated sulfur dioxide and hydrogen chloride gas can more easily form bubbles and aggregate on the surface of the porous material, and then quickly leave the reaction liquid, thereby reducing the contact time between the acidic gas and the product, and significantly improving the optical properties of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 This is the infrared spectrum of the hindered amine light stabilizer prepared in Example 3. DETAILED DESCRIPTION

[0040] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than 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.

[0041] Example 1

[0042] This embodiment provides a method for preparing a high-efficiency, low-alkalinity hindered amine light stabilizer, comprising the following steps:

[0043] Step 1: Preparation of oxidized multilayer graphene and hydroxylated nano-boron nitride

[0044] Weigh: 450.0 mL of 98.0 wt% concentrated sulfuric acid was added to a reactor and stirred at a stirring rate of 80 rpm. During the stirring process, 60.0 g of potassium permanganate powder was added to the reactor. After stirring at room temperature for 5 min, the temperature of the reactor was raised to 30° C. and 12.0 g of multilayer graphene was added to the reactor. The reaction mixture was stirred at this temperature for 2 h. After the reaction was completed, the reaction liquid was filtered to collect the filter cake. The filter cake was washed three times with anhydrous ethanol and deionized water, and then placed in a drying oven at a temperature of 60° C. and vacuum dried until the filter cake had a constant weight, thereby obtaining oxidized multilayer graphene.

[0045] Weigh: 500.0g of nano boron nitride powder, 100.0g of sodium hydroxide and 2.0L of deionized water are added to a high-pressure reactor, the temperature of the high-pressure reactor is increased to 120°C, and the reaction is kept warm for 12 hours. After the reaction is completed, the reaction liquid is filtered to collect the filter cake, and the filter cake is washed three times with anhydrous ethanol and deionized water. The filter cake is placed in a drying oven at a temperature of 60°C and vacuum dried until the filter cake has a constant weight to obtain hydroxylated nano boron nitride.

[0046] Step 2: Preparation of modified catalyst

[0047] Weigh: 200.0g of oxidized multilayer graphene and 2.0L of anhydrous ethanol are dispersed in an ultrasonic instrument and ultrasonicated at an ultrasonic frequency of 20kHz for 30min at room temperature, and 30.0mL of saturated sodium hydroxide solution and 420.0g of hydroxylated nano-boron nitride are added to the ultrasonic instrument. After continuing ultrasonication for 1h, 100.0mL of N,N-diethylchloroformamide is added to the ultrasonic instrument and ultrasonicated for 20min. After the reaction is completed, the reaction liquid is filtered to collect the filter cake, and the filter cake is washed 3 times with anhydrous ethanol and deionized water, and then the filter cake is placed in a drying oven at a temperature of 60°C and vacuum dried until the filter cake has a constant weight to obtain a catalyst precursor;

[0048] Weigh: 400.0g of catalyst precursor, 100.0g of sodium borohydride and 1.0L of deionized water are added into a high-pressure reactor, the temperature of the reactor is raised to 120°C, and the reaction is kept warm for 2h. After the reaction is completed, the reaction liquid is filtered to collect the filter cake, and the filter cake is washed three times with anhydrous ethanol and deionized water, and then placed in a drying oven at a temperature of 60°C and vacuum dried until the filter cake has a constant weight to obtain a modified catalyst.

[0049] Step 3: Preparation of crude hindered amine light stabilizer

[0050] Weigh: 300.0g of sebacic acid and 30.0g of modified catalyst are added to a reactor. After the temperature of the reactor is reduced to 40°C, 700.0g of thionyl chloride is added dropwise to the reactor. After the reaction is kept warm for 1h, the temperature of the reactor is rapidly raised to 70°C and kept warm for 10min. After the reaction is completed, after the temperature of the reactor is reduced to room temperature, 1.6kg of chloroform is added dropwise to the reactor. The reaction solution is transferred to a separatory funnel. After separation, the upper layer of liquid is collected, and the lower layer of liquid is transferred to a rotary evaporator. The internal pressure of the rotary evaporator is reduced to 100mmHg, and the temperature of the rotary evaporator is increased to 30°C. The fractions are collected to obtain thionyl chloride, which is evaporated until no liquid is obtained to obtain sebacyl chloride, and the sebacyl chloride is transferred to the upper layer of liquid to obtain a sebacyl chloride mixed solution;

[0051] Weigh: 1.0 kg of sebacic acid chloride mixed solution and 220.0 g of pentamethylpiperidinol are added to the reactor, the temperature of the reactor is raised to 40°C, and the reaction is kept warm for 2 hours. Then, 15.0 g of methanol is added to the reactor and the reaction is kept warm for 1 hour. After the reaction is completed, the temperature of the reactor is lowered to room temperature, and the reaction solution is transferred to a rotary evaporator with a water bath temperature of 40°C. The solvent is evaporated under reduced pressure to obtain a crude hindered amine light stabilizer.

[0052] Step 4: Preparation of Hindered Amine Light Stabilizer

[0053] Weigh: 100.0 g of oxidized multilayer graphene and 100.0 g of hydroxylated nano-boron nitride to prepare a modified decolorizing agent;

[0054] Weigh: 800.0g of crude hindered amine light stabilizer, 200.0g of modified decolorizer, 500.0mL of 20wt% hydrogen peroxide solution and 3.0L of anhydrous ethanol, add into a reactor and stir, raise the temperature of the reactor to 30°C, and keep warm for 1h. After the reaction is completed, wait for the temperature of the reaction liquid to drop to room temperature, filter the reaction liquid and collect the filtrate, transfer the filtrate to a rotary evaporator with a water bath temperature of 40°C, and evaporate the solvent under reduced pressure to obtain a hindered amine light stabilizer.

[0055] Example 2

[0056] This embodiment provides a method for preparing a high-efficiency, low-alkalinity hindered amine light stabilizer, comprising the following steps:

[0057] Step 1: Preparation of oxidized multilayer graphene and hydroxylated nano-boron nitride

[0058] Weigh: 500.0 mL of 98.0 wt% concentrated sulfuric acid is added to a reactor and stirred at a stirring rate of 120 rpm. During the stirring process, 80.0 g of potassium permanganate powder is added to the reactor. After stirring at room temperature for 10 min, the temperature of the reactor is increased to 45° C. and 20.0 g of multilayer graphene is added to the reactor. The reaction mixture is stirred for 2 h. After the reaction is completed, the reaction liquid is filtered to collect the filter cake. After washing the filter cake with anhydrous ethanol and deionized water for 5 times, the filter cake is placed in a drying oven at a temperature of 60° C. and vacuum dried until the filter cake has a constant weight, thereby obtaining oxidized multilayer graphene.

[0059] Weigh: 600.0g of nano boron nitride powder, 200.0g of sodium hydroxide and 2.5L of deionized water are added to a high-pressure reactor, the temperature of the high-pressure reactor is increased to 150°C, and the reaction is kept warm for 16 hours. After the reaction is completed, the reaction liquid is filtered to collect the filter cake, and the filter cake is washed 5 times with anhydrous ethanol and deionized water. The filter cake is placed in a drying oven at a temperature of 60°C and vacuum dried until the filter cake has a constant weight to obtain hydroxylated nano boron nitride.

[0060] Step 2: Preparation of modified catalyst

[0061] Weigh: 300.0g of oxidized multilayer graphene and 2.5L of anhydrous ethanol are dispersed in an ultrasonic instrument and ultrasonicated at an ultrasonic frequency of 40kHz. Ultrasonication is performed at room temperature for 40min, and 50.0mL of saturated sodium hydroxide solution and 600.0g of hydroxylated nano-boron nitride are added to the ultrasonic instrument. After continuing ultrasonication for 2h, 200.0mL of N,N-diethylchloroformamide is added to the ultrasonic instrument and ultrasonicated for 30min. After the reaction is completed, the reaction liquid is filtered to collect the filter cake, and the filter cake is washed 5 times with anhydrous ethanol and deionized water, and then the filter cake is placed in a drying oven at a temperature of 60°C and vacuum dried until the filter cake has a constant weight to obtain a catalyst precursor;

[0062] Weigh: 500.0g of catalyst precursor, 200.0g of sodium borohydride and 1.2L of deionized water are added into a high-pressure reactor, the temperature of the reactor is raised to 150°C, and the reaction is kept warm for 4 hours. After the reaction is completed, the reaction liquid is filtered to collect the filter cake, and the filter cake is washed 5 times with anhydrous ethanol and deionized water. The filter cake is placed in a drying oven at a temperature of 60°C and vacuum dried until the filter cake has a constant weight to obtain a modified catalyst.

[0063] Step 3: Preparation of crude hindered amine light stabilizer

[0064] Weigh: 400.0g of sebacic acid and 50.0g of modified catalyst are added to a reactor. After the temperature of the reactor is reduced to 50°C, 800.0g of thionyl chloride is added dropwise to the reactor. After the reaction is kept warm for 2h, the temperature of the reactor is rapidly raised to 75°C and kept warm for 15min. After the reaction is completed, after the temperature of the reactor is reduced to room temperature, 1.8kg of chloroform is added dropwise to the reactor. The reaction solution is transferred to a separatory funnel. After separation, the upper layer of liquid is collected, and the lower layer of liquid is transferred to a rotary evaporator. The internal pressure of the rotary evaporator is reduced to 50mmHg, and the temperature of the rotary evaporator is increased to 40°C. The fractions are collected to obtain thionyl chloride, which is evaporated until no liquid is obtained to obtain sebacyl chloride, and the sebacyl chloride is transferred to the upper layer of liquid to obtain a sebacyl chloride mixed solution;

[0065] Weigh: 1.2 kg of sebacic acid chloride mixed solution and 240.0 g of pentamethylpiperidinol are added to the reactor, the temperature of the reactor is raised to 50°C, and the reaction is kept warm for 3 hours. Then, 25.0 g of methanol is added to the reactor and the reaction is kept warm for 2 hours. After the reaction is completed, the temperature of the reactor is lowered to room temperature, and the reaction solution is transferred to a rotary evaporator with a water bath temperature of 50°C. The solvent is evaporated under reduced pressure to obtain a crude hindered amine light stabilizer.

[0066] Step 4: Preparation of Hindered Amine Light Stabilizer

[0067] Weigh: 200.0 g of oxidized multilayer graphene and 100.0 g of hydroxylated nano-boron nitride to prepare a modified decolorizing agent;

[0068] Weigh: 1000.0g of crude hindered amine light stabilizer, 300.0g of modified decolorizer, 800.0mL of 30wt% hydrogen peroxide solution and 4.0L of anhydrous ethanol, add into a reactor and stir, raise the temperature of the reactor to 40°C, and keep warm for 2h. After the reaction is completed, wait for the temperature of the reaction liquid to drop to room temperature, filter the reaction liquid and collect the filtrate, transfer the filtrate to a rotary evaporator with a water bath temperature of 50°C, and evaporate the solvent under reduced pressure to obtain a hindered amine light stabilizer.

[0069] Example 3

[0070] This embodiment provides a method for preparing a high-efficiency, low-alkalinity hindered amine light stabilizer, comprising the following steps:

[0071] Step 1: Preparation of oxidized multilayer graphene and hydroxylated nano-boron nitride

[0072] Weigh: 475.0 mL of 98.0 wt% concentrated sulfuric acid is added to a reactor and stirred at a stirring rate of 100 rpm. During the stirring process, 700.0 g of potassium permanganate powder is added to the reactor. After stirring at room temperature for 8 minutes, the temperature of the reactor is increased to 36° C. and 150.0 g of multilayer graphene is added to the reactor. The reaction mixture is stirred for 3 hours. After the reaction is completed, the reaction liquid is filtered to collect the filter cake. After washing the filter cake 4 times with anhydrous ethanol and deionized water, the filter cake is placed in a drying oven at a temperature of 60° C. and vacuum dried until the filter cake has a constant weight, thereby obtaining oxidized multilayer graphene.

[0073] Weigh: 550.0g of nano boron nitride powder, 150.0g of sodium hydroxide and 2.3L of deionized water are added to a high-pressure reactor, the temperature of the high-pressure reactor is increased to 135°C, and the reaction is kept warm for 14 hours. After the reaction is completed, the reaction liquid is filtered to collect the filter cake, and the filter cake is washed 4 times with anhydrous ethanol and deionized water. The filter cake is placed in a drying oven at a temperature of 60°C and vacuum dried until the filter cake has a constant weight to obtain hydroxylated nano boron nitride.

[0074] Step 2: Preparation of modified catalyst

[0075] Weigh: 250.0g of oxidized multilayer graphene and 2.1L of anhydrous ethanol are dispersed in an ultrasonic instrument and ultrasonicated at an ultrasonic frequency of 30kHz for 35min at room temperature, and 40.0mL of saturated sodium hydroxide solution and 500.0g of hydroxylated nano-boron nitride are added to the ultrasonic instrument. After continuing ultrasonication for 2h, 150.0mL of N,N-diethylchloroformamide is added to the ultrasonic instrument and ultrasonicated for 25min. After the reaction is completed, the reaction liquid is filtered to collect the filter cake, and the filter cake is washed 4 times with anhydrous ethanol and deionized water, and then the filter cake is placed in a drying oven at a temperature of 60°C and vacuum dried until the filter cake has a constant weight to obtain a catalyst precursor;

[0076] Weigh: 450.0g of catalyst precursor, 150.0g of sodium borohydride and 1.2L of deionized water are added into a high-pressure reactor, the temperature of the reactor is raised to 135°C, and the reaction is kept warm for 4 hours. After the reaction is completed, the reaction liquid is filtered to collect the filter cake, and the filter cake is washed 4 times with anhydrous ethanol and deionized water, and then placed in a drying oven at a temperature of 60°C and vacuum dried until the filter cake has a constant weight to obtain a modified catalyst.

[0077] Step 3: Preparation of crude hindered amine light stabilizer

[0078] Weigh: 350.0g of sebacic acid and 40.0g of modified catalyst are added to a reactor. After the temperature of the reactor is reduced to 45°C, 750.0g of thionyl chloride is added dropwise to the reactor. After the reaction is kept warm for 2h, the temperature of the reactor is rapidly raised to 72°C and kept warm for 12min. After the reaction is completed, after the temperature of the reactor is reduced to room temperature, 1.8kg of chloroform is added dropwise to the reactor. The reaction solution is transferred to a separatory funnel. After separation, the upper layer of liquid is collected, and the lower layer of liquid is transferred to a rotary evaporator. The internal pressure of the rotary evaporator is reduced to 75mmHg, and the temperature of the rotary evaporator is increased to 35°C. The fractions are collected to obtain thionyl chloride, which is evaporated until no liquid is obtained to obtain sebacyl chloride. The sebacyl chloride is transferred to the upper layer of liquid to obtain a sebacyl chloride mixed solution;

[0079] Weigh: 1.2 kg of sebacic acid chloride mixed solution and 250.0 g of pentamethylpiperidinol are added to the reactor, the temperature of the reactor is raised to 45 ° C, and the reaction is kept warm for 2 hours. Then, 30.0 g of methanol is added to the reactor and the reaction is kept warm for 2 hours. After the reaction is completed, the temperature of the reactor is lowered to room temperature, and the reaction liquid is transferred to a rotary evaporator with a water bath temperature of 45 ° C. The solvent is evaporated under reduced pressure to obtain a crude hindered amine light stabilizer.

[0080] Step 4: Preparation of Hindered Amine Light Stabilizer

[0081] Weigh: 150.0 g of oxidized multilayer graphene and 100.0 g of hydroxylated nano-boron nitride to prepare a modified decolorizing agent;

[0082] Weigh: 900.0g of crude hindered amine light stabilizer, 250.0g of modified decolorizer, 600.0mL of 20-30wt% hydrogen peroxide solution and 3.5L of anhydrous ethanol, add them into a reactor and stir, raise the temperature of the reactor to 35°C, and keep the reaction for 2h. After the reaction is completed, after the temperature of the reaction liquid is lowered to room temperature, filter the reaction liquid and collect the filtrate, transfer the filtrate to a rotary evaporator with a water bath temperature of 45°C, and evaporate the solvent under reduced pressure to obtain a hindered amine light stabilizer.

[0083] Comparative Example 1

[0084] The difference between this comparative example and Example 3 is that step 2 is eliminated and the use of a modified catalyst is eliminated in step 3.

[0085] Comparative Example 2

[0086] The difference between this comparative example and Example 3 is that in the process of preparing the catalyst precursor in step 2, the addition of hydroxylated nano-boron nitride is omitted.

[0087] Comparative Example 3

[0088] The difference between this comparative example and Example 3 is that the modified decolorizing agent and 20-30 wt % hydrogen peroxide solution are omitted in step 4.

[0089] Performance Testing:

[0090] The chromaticity of the hindered amine light stabilizers prepared in Examples 1-3 and Comparative Examples 1-3 was measured with reference to the standard DB13 / T 1230-2010 "Method for Determining Chromaticity of Organic Chemical Products";

[0091] The purity w of hindered amine light stabilizer was analyzed by gas chromatography using the formula , where w represents the purity of the hindered amine light stabilizer, m represents the mass of the hindered amine light stabilizer, and m 癸二酰氯 represents the mass of sebacic acid chloride, M represents the molar mass of hindered amine light stabilizer, M 癸二酰氯 represents the molar mass of sebacyl chloride, and the yield η of hindered amine light stabilizer is calculated. The specific data are shown in Table 1;

[0092] The modified catalyst prepared in Example 2-3 was reused, and the purity and yield of the hindered amine light stabilizer sample prepared when it was reused for the tenth time were measured. The specific data are shown in Table 2.

[0093] Table 1-Performance test data of each sample

[0094] Table 2 - Cyclic test performance of catalysts

[0095]

[0096] By analyzing the data in Table 1 above, it can be found that the chromaticity of the hindered amine light stabilizer prepared by the present invention is 10 hazen, the purity is 99.9% and the yield is 99.9%. After ten cycles, the purity of the hindered amine light stabilizer prepared by using the catalyst is 99.7% and the yield is 99.8%.

[0097] Data analysis: By comparing the data in Table 1, it can be found that the present invention is to prepare oxidized multilayer graphene and hydroxylated nano-boron nitride as modified decolorizing agents for decolorization treatment, and to modify hydroxylated nano-boron nitride on the surface of oxidized multilayer graphene as a matrix to make its structure more stable, and finally to graft catalytic segments on its surface to obtain catalytic segments, so that the reaction is more efficient, and the ring structure makes the lone pair of electrons of the nitrogen atom more stable, thereby reducing the alkalinity of the system;

[0098] By comparing the data in Table 2, it can be found that the catalyst modified by hydroxylated nano-boron nitride is more stable in the highly active dichlorothionyl system, and hydroxylated nano-boron nitride has a certain filling effect on the internal structure of oxidized multilayer graphene, making its structure stable and ensuring its recycling performance.

[0099] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a high-efficiency, low-alkalinity hindered amine light stabilizer, characterized in that: The following steps are involved: S1, add sebacic acid and modified catalyst into a reactor, after the temperature of the reactor is reduced to 40-50°C, add dithionyl chloride dropwise into the reactor, keep warm for 1-2h, then quickly raise the temperature of the reactor to 70-75°C, keep warm for 10-15min, after the reaction is completed, add chloroform after the temperature of the reactor is reduced to room temperature, and recover the sebacic acid chloride mixture and dithionyl chloride by post-processing; S2, adding the sebacic acid chloride mixture and pentamethylpiperidinol into a reactor, raising the temperature of the reactor to 40-50°C, keeping the temperature for reaction for 2-3 hours, adding methanol into the reactor, keeping the temperature for reaction for 1-2 hours, and post-treating to obtain a crude hindered amine light stabilizer; S3. Add the crude hindered amine light stabilizer, modified decolorizer, 20-30wt% hydrogen peroxide solution and anhydrous ethanol into a reactor and stir. Raise the temperature of the reactor to 30-40°C, keep the reaction warm for 1-2h, and post-treat to obtain the hindered amine light stabilizer.

2. The method for preparing a high-efficiency, low-alkalinity hindered amine light stabilizer according to claim 1, characterized in that: In step S1, the dosage ratio of sebacic acid, modified catalyst, dithionyl chloride and chloroform is 3-4g:0.3-0.5g:7-8g:16-18g, and the post-treatment recovery operation is as follows: after the reaction is completed, after the temperature of the reactor is lowered to room temperature, chloroform is added dropwise to the reactor, the reaction solution is transferred to a separatory funnel, the upper layer of liquid is collected after separation, and the lower layer of liquid is transferred to a rotary evaporator, the internal pressure of the rotary evaporator is reduced to 50-100mmHg, the temperature of the rotary evaporator is increased to 30-40°C, the fraction is collected to obtain dithionyl chloride, and the distillate is evaporated until no liquid is extracted to obtain sebacyl chloride, and the sebacyl chloride is transferred to the upper layer of liquid to obtain a sebacyl chloride mixed solution.

3. The method for preparing a high-efficiency, low-alkalinity hindered amine light stabilizer according to claim 1, characterized in that: In step S1, the preparation method of the modified catalyst comprises the following steps: A1. Disperse the oxidized multilayer graphene and anhydrous ethanol in an ultrasonic instrument and ultrasonicate for 30-40 min at room temperature, add a saturated sodium hydroxide solution and hydroxylated nano-boron nitride to the ultrasonic instrument, continue ultrasonicating for 1-2 h, add N,N-diethylchloroformamide to the ultrasonic instrument, ultrasonicate for 20-30 min, and perform post-treatment to obtain a catalyst precursor; A2. Add the catalyst precursor, sodium borohydride and deionized water into a high-pressure reactor, increase the temperature of the reactor to 120-150° C., keep the temperature for 2-4 hours, and perform post-treatment to obtain a modified catalyst.

4. The method for preparing a high-efficiency, low-alkalinity hindered amine light stabilizer according to claim 3, characterized in that: In step A1, the ultrasonic frequency of the ultrasonic instrument is 20-40kHz, and the dosage ratio of oxidized multilayer graphene, anhydrous ethanol, saturated sodium hydroxide solution, hydroxylated nano-boron nitride and N,N-diethylchloroformamide is 2-3g:20-25mL:0.3-0.5mL:4-6g:1-2mL; in step A2, the dosage ratio of catalyst precursor, sodium borohydride and deionized water is 4-5g:1-2g:10-12mL.

5. The method for preparing a high-efficiency, low-alkalinity hindered amine light stabilizer according to claim 3, characterized in that: In step A1, the method for preparing oxidized multilayer graphene and hydroxylated nano-boron nitride comprises the following steps: B1, adding 98.0wt% concentrated sulfuric acid to a reactor and stirring, adding potassium permanganate powder to the reactor during stirring, stirring at room temperature for 5-10min, raising the temperature of the reactor to 30-45°C and adding multilayer graphene to the reactor, keeping the temperature and stirring for 2-3h, and post-treating to obtain oxidized multilayer graphene; B2. Add nano boron nitride powder, sodium hydroxide and deionized water into a high-pressure reactor, increase the temperature of the high-pressure reactor to 120-150° C., keep the temperature for 12-16 hours, and perform post-treatment to obtain hydroxylated nano boron nitride.

6. The method for preparing a high-efficiency, low-alkalinity hindered amine light stabilizer according to claim 5, characterized in that: In step B1, the stirring rate of the reactor is 80-120rpm, and the usage ratio of 98.0wt% concentrated sulfuric acid, potassium permanganate powder and multilayer graphene is 45-50mL:6-8g:1-2g; in step B2, the usage ratio of nano boron nitride powder, sodium hydroxide and deionized water is 5-6g:1-2g:20-25mL.

7. The method for preparing a high-efficiency, low-alkalinity hindered amine light stabilizer according to claim 1, characterized in that: In step S2, the usage ratio of the sebacic acid chloride mixed solution, pentamethylpiperidinol, and methanol is 10-12 g: 2-3 g: 0.1-0.3 g.

8. The method for preparing a high-efficiency, low-alkalinity hindered amine light stabilizer according to claim 1, characterized in that: In step S3, the usage ratio of the crude hindered amine light stabilizer, the modified decolorizing agent, the 20-30wt% hydrogen peroxide solution and the anhydrous ethanol is 8-10g:2-3g:5-8mL:30-40mL, and the modified decolorizing agent is obtained by mixing the oxidized multilayer graphene and the hydroxylated nano-boron nitride in a mass ratio of 1-2g:1g.

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