Hindered phenol antioxidant and preparation method thereof

Abstract

The invention discloses a hindered phenol antioxidant and a preparation method thereof in the field of high polymer material auxiliaries, and the antioxidant comprises a modified hindered phenol compound A, a modified hindered phenol compound B, tris (2, 4-di-tert-butylphenyl) phosphite, distearyl thiodipropionate, a hindered amine light stabilizer and an antioxidant carrier. The modified hindered phenol compound A is prepared by taking 4, 6-di-tert-butylresorcinol as a raw material, reacting the raw material with chloroethyl sulfonyl chloride in potassium hydroxide and N, N-dimethylformamide, then adding ethylenediamine for continuous reaction, and carrying out ice water precipitation, ethanol recrystallization and vacuum drying. The antioxidant is prepared by the following steps: adding the components into a high-speed mixer for premixing, transferring to a double-screw extruder for melt extrusion, granulating and drying.

Description

Technical Field

[0001] This invention relates to the field of polymer material additives technology, specifically to a hindered phenolic antioxidant and its preparation method. Background Technology

[0002] Hindered phenolic antioxidants, as indispensable stabilizing agents in the processing and long-term use of polymer materials, effectively inhibit the aging and degradation of materials caused by factors such as heat, oxygen, and light through the capture of free radicals by the phenolic hydroxyl group and the steric hindrance effect of the ortho-tert-butyl group. They are widely used in plastics, rubber, and synthetic fibers. However, while traditional hindered phenolic antioxidants possess basic antioxidant capabilities, they have significant drawbacks: First, in high-temperature processing scenarios, the phenolic hydroxyl group is prone to dehydrogenation or cleavage reactions, leading to the decomposition of the antioxidant itself. This not only reduces the protective efficacy but may also release small molecule byproducts that affect material performance. Second, during long-term use, antioxidant molecules migrate to the material surface due to thermal motion and gradually precipitate, causing the product surface to become sticky, lose gloss, and even contaminate the contact medium. Third, the synergistic effect of a single hindered phenolic structure and auxiliary antioxidants is limited, making it difficult to cope with multi-factor aging problems under complex environments, thus restricting their application in high-performance materials.

[0003] To address the shortcomings of traditional hindered phenolic antioxidants, such as easy decomposition at high temperatures, poor migration resistance, and insufficient polymer compatibility, existing technologies mostly improve their overall performance through chemical modification. Some studies attempt to introduce polar groups (such as sulfonamides) at the ortho or para positions of the phenolic hydroxyl group, utilizing polar interactions to enhance the interfacial bonding between the antioxidant and the polymer, thereby improving migration resistance. Other studies introduce long-chain alkyl groups (such as octadecanool) or rigid heterocyclic structures to increase molecular steric hindrance, thus delaying thermal decomposition and improving processing fluidity. For example, patent CN113292431B discloses a method for preparing a hindered phenolic antioxidant. Using 2,6-di-tert-butylphenol as a raw material, it reacts with methyl propargylate in acetonitrile under potassium carbonate catalysis to generate an intermediate, which is then alkylated with octadecanool via tetraethyl titanate catalysis to obtain the target product, with a yield of 95%. This method attempts to enhance the migration resistance of the antioxidant by introducing long-chain alkyl groups (octadecanool) while simultaneously optimizing the molecular structure through alkylation. However, such modification methods involving single functional groups or simple alkylation still have limitations: the introduction of polar groups (such as sulfonamides) may improve thermal stability, but may lead to decreased compatibility with hydrophobic polymers due to excessive polarity; the introduction of long-chain alkyl groups may enhance migration resistance, but may increase intermolecular entanglement and reduce processing fluidity; moreover, existing compound systems mostly rely on physical blending, resulting in uneven dispersion of components and weak interfacial bonding between antioxidants and polymers, making it difficult to achieve multiple optimizations of thermal stability, migration resistance, and synergistic effects, thus limiting the improvement of overall protective efficacy.

[0004] Against the backdrop of the aforementioned technologies, there is an urgent need to develop a novel hindered phenolic antioxidant that combines high thermal stability, low migration, and excellent synergistic effects. This invention addresses the problems of traditional products—such as easy decomposition at high temperatures, long-term migration, and insufficient synergistic effects—by designing two novel modified hindered phenolic compounds and introducing sulfonamide and phosphonate functional groups, respectively. Utilizing the synergistic effects of steric hindrance, hydrogen bonding, and free radical scavenging capabilities, combined with an optimized compounding process, the invention effectively solves these problems. Modified hindered phenolic compound A, through a grafting reaction of chloroethylsulfonyl chloride and ethylenediamine, constructs a sterically hindered structure containing sulfonamide side chains on the hindered phenolic core. This enhances intramolecular hydrogen bonding to improve thermal stability and reduces migration tendency through the interaction of polar groups with the polymer. Modified hindered phenolic compound B, through the substitution of the phenolic hydroxyl group with a phosphonate di(octadecyl) ester group, utilizes the high reactivity of phosphonates and the steric effect of long-chain alkyl groups to significantly improve free radical scavenging efficiency and processing fluidity. Furthermore, by employing high-speed mixing and melt blending processes, the components are uniformly dispersed in the polymer matrix to form a synergistic network, ultimately producing a hindered phenolic antioxidant with excellent comprehensive performance. This provides a new technical solution for the high performance and long-term stabilization of polymer materials. Summary of the Invention

[0005] The purpose of this invention is to provide a hindered phenolic antioxidant and its preparation method, which solves the technical problems of existing hindered phenolic antioxidants, such as easy decomposition at high temperatures, poor migration resistance, and weak synergistic effect with auxiliary antioxidants.

[0006] The present invention achieves the above objectives through the following technical solutions: A hindered phenolic antioxidant comprises the following raw materials in parts by weight: Modified hindered phenolic compound A: 10-50 parts by weight; Modified hindered phenolic compound B: 20-60 parts by weight; Tris(2,4-di-tert-butylphenyl) phosphite: 50-100 parts by weight; Dioctadecyl thiodipropionate: 80-120 parts by weight; Hindered amine light stabilizer: 30-50 parts by weight; Antioxidant carrier: 20-40 parts by weight The preparation method of the modified hindered phenolic compound A includes: A1, adding 4,6-di-tert-butylresorcinol, potassium hydroxide and N,N-dimethylformamide to a reaction vessel, stirring evenly, heating to 80-84℃, adding a solution of N,N-dimethylformamide in chloroethylsulfonyl chloride dropwise, and maintaining the temperature for reaction after the addition is complete; A2, then cooling to 50-52℃, adding a solution of N,N-dimethylformamide in ethylenediamine, and continuing the reaction; A3, after the reaction is complete, pouring the system into ice water to precipitate, filtering to obtain the crude product, recrystallizing with ethanol and drying under vacuum.

[0007] In this invention, the reaction mechanism for modifying hindered phenolic compound A originates from the chemical modification process of 4,6-di-tert-butylresorcinol. Its core lies in introducing a sulfonamide functional group onto the phenolic hydroxyl group through a two-step nucleophilic substitution reaction. First, the hydroxyl group in the 4,6-di-tert-butylresorcinol molecule dissociates under alkaline conditions (potassium hydroxide), forming a negatively charged oxygen anion, significantly enhancing its nucleophilicity. At this point, chloroethylsulfonyl chloride, introduced into the reaction system, acts as an electrophile; its chlorine atom, bonded to a highly electronegative sulfur atom, possesses a high leaving ability. Under the action of the polar aprotic solvent N,N-dimethylformamide, the oxygen anion launches a nucleophilic attack on the α-carbon atom of chloroethylsulfonyl chloride, forming a transition state and ultimately completing the substitution of the chlorine atom, generating the intermediate product 4,6-di-tert-butylresorcinol mono(chloroethylsulfonyl) ether. The key to this step lies in the activation of the hydroxyl group by the alkaline environment and the stability of the reaction transition state by the solvent, ensuring the efficient conduct of the substitution reaction. Subsequently, after cooling the reaction system, ethylenediamine was added. The amino group (-NH2) in the ethylenediamine molecule, acting as a new nucleophilic group, continued to attack the sulfonyl chloride moiety in the intermediate. The sulfur atom in the sulfonyl chloride, being electron-deficient due to its connection with two highly electronegative oxygen atoms, became the nucleophilic attack site. The nitrogen atom of the amino group in ethylenediamine donated a lone pair of electrons, forming a new covalent bond with the sulfur atom, while simultaneously causing the chlorine atom to detach as a leaving group, ultimately generating a modified hindered phenolic compound A containing a sulfonamide bond (-SO2-NH-). This reaction step not only completed the construction of the sulfonamide side chain but also formed an intramolecular hydrogen bond network through the introduction of the amino group (the NH bond of the sulfonamide interacts with the OH bond of the adjacent hydroxyl group). This hydrogen bonding significantly enhanced the thermal stability of compound A, laying the structural foundation for its antioxidant properties in high-temperature processing scenarios.

[0008] According to a preferred embodiment of the present invention, the 4,6-di-tert-butylresorcinol was purchased from Jiangsu Runfeng Synthetic Technology Co., Ltd., and its model number is R-100.

[0009] According to a preferred embodiment of the present invention, the potassium hydroxide was purchased from Qinghai Salt Lake Industry Co., Ltd., and is of industrial grade superior quality.

[0010] According to a preferred embodiment of the present invention, the N,N-dimethylformamide was purchased from Jiangsu Huachang Chemical Co., Ltd., and the model was DMF-99.9%.

[0011] According to a preferred embodiment of the present invention, the reactor was purchased from Weihai Chemical Machinery Co., Ltd., and is a GSH-500L glass-lined reactor.

[0012] According to a preferred embodiment of the present invention, the chloroethylsulfonyl chloride was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0013] According to a preferred embodiment of the present invention, the ethylenediamine was purchased from Jiangsu Feixiang Chemical Co., Ltd., and the product type is EDA-industrial grade.

[0014] According to a preferred embodiment of the present invention, the ethanol was purchased from COFCO Biotechnology Co., Ltd., and the product is food-grade anhydrous ethanol.

[0015] According to a preferred embodiment of the present invention, the tris(2,4-di-tert-butylphenyl) phosphite was purchased from Jiangsu Yake Technology Co., Ltd., and the grade was 168-industrial grade.

[0016] According to a preferred embodiment of the present invention, the dioctadecyl thiodipropionate was purchased from Jiangsu Haian Petrochemical Technology Co., Ltd., and the product name is DSTDP-99.

[0017] According to a preferred embodiment of the present invention, the hindered amine light stabilizer was purchased from Jiangsu Litian Technology Co., Ltd., and its model is light stabilizer 770.

[0018] According to a preferred embodiment of the present invention, the antioxidant carrier is purchased from Sinopec Yangzi Petrochemical Co., Ltd., and the model is low molecular weight polypropylene PP-2401.

[0019] According to a preferred embodiment of the present invention, in step A1, the heat preservation reaction time is 4-6 hours.

[0020] According to a preferred embodiment of the present invention, in step A2, the reaction continues for 8-10 hours.

[0021] According to a preferred embodiment of the present invention, in step A3, the ethanol is recrystallized 3-4 times; the vacuum drying temperature is 60-64°C and the time is 12-14 hours.

[0022] According to a preferred embodiment of the present invention, the method for preparing the modified hindered phenolic compound B includes: B1, adding 2,6-di-tert-butyl-4-methoxyphenol, phosphorus oxychloride and toluene to a round-bottom flask, and reacting under nitrogen protection by reflux; after the reaction is completed, distilling under reduced pressure to obtain 2,6-di-tert-butyl-4-chlorophenoxyphosphorus intermediate; B2, adding the intermediate and tri(octadecyl) phosphite to tetrahydrofuran, adding pyridine, and heating to 70-74°C to react; filtering the reaction solution to remove pyridine hydrochloride, concentrating the filtrate under reduced pressure, and purifying by column chromatography.

[0023] In this invention, the reaction mechanism for modifying hindered phenolic compound B revolves around phosphorylation, the core of which involves introducing a phosphonate group into the phenolic hydroxyl position through a two-step substitution reaction. First, the methoxy group (-OCH3) in the 2,6-di-tert-butyl-4-methoxyphenol molecule undergoes phosphorylation in the presence of phosphorus pentachloride (POCl3). The phosphorus atom in phosphorus pentachloride has an empty d orbital, exhibiting a strong affinity for oxygen atoms. The oxygen atom of the methoxy group acts as a nucleophilic center, attacking the phosphorus atom and gradually replacing the chlorine atom on the phosphorus atom, forming the intermediate 2,6-di-tert-butyl-4-chlorophenoxytrichlorophosphine. This step is carried out under toluene reflux conditions. The high temperature promotes the departure of the chlorine atom and the formation of the phosphorus-oxygen bond, while vacuum distillation removes excess phosphorus pentachloride by reducing the system pressure, ensuring the purity of the intermediate. Subsequently, the intermediate undergoes a phosphorus-oxygen bond exchange reaction with tri(octadecyl) phosphite in tetrahydrofuran. In the tri(octadecyl) phosphite molecule, the phosphorus atom is bonded to three octadecyloxy groups, exhibiting a strong electron-donating ability; while in the intermediate product, the phosphorus atom is in a highly electron-deficient state due to its bond to two chlorine atoms. Under the neutralization of pyridine (as an acid-binding agent), the chlorine atom in the intermediate product is replaced by the octadecyloxy group of the tri(octadecyl) phosphite, forming a di(octadecyl) phosphonate structure. The key to this reaction step lies in the absorption of hydrogen chloride generated by the acid-binding agent, preventing the acidic environment from destroying the phosphorylated product. Simultaneously, the polarity of the solvent tetrahydrofuran promotes the nucleophilic substitution reaction. The resulting modified hindered phenolic compound B significantly enhances its free radical scavenging ability through the high reactivity of the phosphonate group (high phosphorus-oxygen double bond energy), while the long octadecyl chain reduces the molecular thermal activity through steric hindrance, improving the antioxidant's resistance to migration.

[0024] According to a preferred embodiment of the present invention, the 2,6-di-tert-butyl-4-methoxyphenol was purchased from Jiangsu Runfeng Synthetic Technology Co., Ltd., and the model number is RT-264.

[0025] According to a preferred embodiment of the present invention, the phosphorus oxychloride was purchased from Jiangsu Feixiang Chemical Co., Ltd., and is an industrial-grade superior product.

[0026] According to a preferred embodiment of the present invention, the toluene was purchased from Sinopec Yangzi Petrochemical Co., Ltd., and is industrial grade solvent toluene.

[0027] According to a preferred embodiment of the present invention, the round-bottom flask was purchased from Sichuan Shubo (Group) Co., Ltd., and is a 5000mL high borosilicate glass round-bottom flask.

[0028] According to a preferred embodiment of the present invention, the nitrogen gas is purchased from Yingde Gases (Shanghai) Co., Ltd., and is high-purity nitrogen gas (purity ≥99.999%).

[0029] According to a preferred embodiment of the present invention, the tri(octadecyl) phosphite was purchased from Jiangsu Haian Petrochemical Technology Co., Ltd., and the product name was TMP-18-99.

[0030] According to a preferred embodiment of the present invention, the tetrahydrofuran is purchased from Jiangsu Yida Chemical Co., Ltd., and is industrial grade tetrahydrofuran.

[0031] According to a preferred embodiment of the present invention, the pyridine was purchased from Jiangsu Xuzhou Jianping Chemical Co., Ltd., and the product was industrial grade pyridine (purity ≥99.5%).

[0032] According to a preferred embodiment of the present invention, the high-speed mixer was purchased from Changzhou Jintan Liangyou Machinery Co., Ltd., and the model is SHR-1000 high-speed mixer.

[0033] According to a preferred embodiment of the present invention, the twin-screw extruder was purchased from Nanjing Keya Chemical Complete Equipment Co., Ltd., and is a TE-60 twin-screw extruder.

[0034] According to a preferred embodiment of the present invention, in step B1, the reflux reaction time is 6-8 hours.

[0035] According to a preferred embodiment of the present invention, in step B2, the reaction time at 70-74°C is 12-14 hours.

[0036] The present invention also provides a method for preparing the hindered phenolic antioxidant, comprising the following steps: S1. Modified hindered phenolic compound A, modified hindered phenolic compound B, tris(2,4-di-tert-butylphenyl) phosphite, dioctadecyl thiodipropionate, hindered amine light stabilizer, and antioxidant carrier are added to a high-speed mixer for premixing. S2. Transfer to a twin-screw extruder for melt extrusion, granulation, and drying.

[0037] In this invention, the synergistic mechanism of hindered phenolic antioxidants is manifested in the structural complementarity and functional synergy of multiple components. Modified hindered phenolic compounds A and B, as primary antioxidants, exert their core antioxidant effects through the hydrogen bonding network of sulfonamide groups and the high reactivity of phosphonate groups, respectively: A delays its own thermal decomposition through intramolecular hydrogen bonds, extending the effective protection time; B rapidly captures alkyl and peroxide free radicals through its phosphonate groups, inhibiting the propagation of the oxidation chain reaction. Tris(2,4-di-tert-butylphenyl) phosphite, as a secondary antioxidant, decomposes hydroperoxides (ROOH) to generate stable alcohol compounds, reducing the source of free radical generation and forming a dual protection chain of "free radical capture - peroxide decomposition" with the primary antioxidant. Dioctadecanol thiodipropionate reacts with free radicals through its thioether structure (-S-) to generate stable thioether free radicals, further blocking the expansion of the chain reaction and enhancing the overall antioxidant efficiency. The addition of hindered amine light stabilizers provides long-lasting photoprotection for the material. The piperidine ring structure in their molecules can capture excited-state free radicals induced by ultraviolet radiation, inhibiting photodegradation reactions and complementing the antioxidant mechanism of hindered phenols in a time-dependent manner (thermal oxidation protection and photo-oxidation protection). Antioxidant carriers (such as low molecular weight polypropylene) improve the dispersibility of each component through physical blending. Their melt flowability promotes the uniform distribution of antioxidants in the polymer matrix, forming a continuous protective network. The components are tightly bound together through intermolecular forces (such as van der Waals forces and hydrogen bonds) and interfacial interactions, working synergistically during processing and use, ultimately achieving comprehensive and long-lasting stabilization and protection for the polymer material.

[0038] According to a preferred embodiment of the present invention, in step S1, the rotation speed of the high-speed mixer is 800-1000 rpm; the premixing time is 5-10 min.

[0039] According to a preferred embodiment of the present invention, in step S2, the temperature of the twin-screw extruder is 180-220°C, the screw speed is 200-400 rpm, the granulation drying temperature is 60-64°C, and the time is 4-6 hours.

[0040] The beneficial effects of this invention are as follows: 1. The hindered phenolic antioxidants of this invention, through novel modified structural design and multi-component synergistic compounding, exhibit significant advantages in thermal stability, migration resistance, and comprehensive protective efficacy. Modified hindered phenolic compound A uses resorcinol containing tert-butyl as the core, and the introduction of sulfonamide side chains forms an intramolecular hydrogen bond network, effectively inhibiting the dehydrogenation decomposition reaction of the phenolic hydroxyl group during high-temperature processing. This significantly increases the antioxidant's own thermal decomposition temperature, enabling it to maintain structural integrity at higher temperatures and avoiding protective failure due to high-temperature decomposition. Modified hindered phenolic compound B replaces the phenolic hydroxyl group with a phosphonate group, utilizing the high reactivity of the phosphorus-oxygen double bond to enhance the capture ability of alkyl and peroxy radicals. Simultaneously, the long-chain alkyl structure increases intermolecular entanglement, significantly reducing the antioxidant's migration tendency to the material surface. During long-term use, the amount of precipitation is greatly reduced, solving the problem of surface stickiness caused by easy migration in traditional products.

[0041] 2. The synergistic combination of two modified hindered phenolic compounds further amplifies the overall protective efficacy. Modified hindered phenolic compound A forms a tight interfacial bond with the polymer matrix through the polar effect of the sulfonamide group, improving the uniformity of antioxidant dispersion in the material. Modified hindered phenolic compound B, with its highly reactive phosphonate group, constructs a free radical scavenging network, synergistically decomposing hydrogen peroxide with the auxiliary antioxidant and inhibiting the transmission of thermal oxidation chain reactions. The addition of hindered amine light stabilizers provides long-lasting photoprotection and reduces UV-induced oxidative degradation. The antioxidant carrier improves processing fluidity, allowing for more uniform dispersion of each component in the polymer matrix, forming a synergistic network, ultimately achieving multiple protections of "primary antioxidant - auxiliary stabilizer - photoprotection - processing optimization".

[0042] 3. In practical applications, this antioxidant exhibits excellent dispersibility and thermal stability during polymer material processing, effectively reducing yellowing and degradation in high-temperature processes such as extrusion and injection molding. During long-term use, its low migration characteristics prevent appearance and performance degradation caused by antioxidant precipitation, significantly extending the material's service life. Whether for polyolefins, engineering plastics, or rubber, this antioxidant provides more comprehensive protection, meeting the long-term stabilization requirements of high-performance materials. Detailed Implementation

[0043] The following detailed embodiments are only used to further illustrate this application and should not be construed as limiting the scope of protection of this application. Those skilled in the art can make some non-essential improvements and adjustments to this application based on the above application content.

[0044] Example 1 Preparation of modified hindered phenolic compound A: 100g of 4,6-di-tert-butylresorcinol, 50g of potassium hydroxide, and 300g of N,N-dimethylformamide were added to a reaction vessel. The stirrer was turned on and stirred at 200 rpm for 10 minutes until the materials were completely dissolved. Then, the temperature was raised to 82℃, and 150g of chloroethylsulfonyl chloride dissolved in 150mL of N,N-dimethylformamide solution was slowly added dropwise through a constant pressure dropping funnel at a rate of 5mL / min. After the addition was completed, the temperature was maintained and the reaction was continued for 5 hours. During this period, the reaction temperature was recorded every 30 minutes, and the stirring speed was adjusted to maintain uniform mixing. After the temperature maintenance, the reaction system temperature was lowered to 51℃, and 120g of ethylenediamine dissolved in 200mL of N,N-dimethylformamide solution was added dropwise through a constant pressure dropping funnel at a rate of 3mL / min. After the addition was completed, the temperature was maintained at 51℃ and the reaction was continued for 9 hours. During the reaction, the concentration of intermediate products was measured every hour until the reaction was complete. After the reaction was complete, the reaction solution was slowly poured into a beaker containing 500 mL of ice water and stirred until precipitation was complete. The crude product was collected by suction filtration using a Buchner funnel. The crude product was then placed in a beaker and 200 mL of ethanol was added. The mixture was heated to 70 °C and stirred to dissolve. The mixture was then filtered while hot to remove insoluble impurities. After the filtrate was cooled to room temperature, crystals precipitated. The recrystallization operation was repeated three times. Finally, the crystals were placed in a vacuum drying oven and dried at 62 °C and a vacuum of -0.09 MPa for 13 hours to obtain a white powdery modified hindered phenol compound A.

[0045] Preparation of modified hindered phenolic compound B: 100g of 2,6-di-tert-butyl-4-methoxyphenol, 180g of phosphorus oxychloride, and 200g of toluene were added to a round-bottom flask. A reflux condenser was installed, and nitrogen gas was introduced to purge air. A magnetic stirrer was turned on and stirred at 300 rpm. The flask was placed in an oil bath and heated to the reflux temperature of toluene (approximately 110°C). The reflux reaction was maintained for 7 hours, with 5mL of nitrogen gas added every hour to maintain an anaerobic environment. After reflux, the oil bath heating was turned off. When the flask cooled to 80°C, excess phosphorus oxychloride was distilled off using a vacuum distillation apparatus at -0.08MPa and 60°C. The remaining liquid was collected as the intermediate 2,6-di-tert-butyl-4-chlorophenoxyphosphorus. 120 g of the intermediate and 250 g of trioctadecyl phosphite were added to 500 mL of tetrahydrofuran. After stirring and dissolving, 150 g of pyridine was added as an acid-binding agent. The mixture was transferred to a constant-pressure dropping funnel and added dropwise to a tetrahydrofuran solution heated to 72 °C at a rate of 10 mL / min. After the addition was complete, the reaction was continued at 72 °C for 13 hours, with a water bath used to maintain a stable temperature during the reaction. After the reaction was completed, the mixture was filtered, and the filter cake was washed twice with 50 mL of tetrahydrofuran. The filtrate and washings were combined and concentrated under reduced pressure to remove the tetrahydrofuran solvent. The remaining concentrate was purified by silica gel column chromatography using a 10:1 volume ratio of petroleum ether to ethyl acetate as the eluent. The target fraction was collected, and the eluent was removed by rotary evaporation to obtain a yellow, viscous liquid modified hindered phenol compound B.

[0046] Preparation of hindered phenolic antioxidants: 30g of modified hindered phenolic compound A, 40g of modified hindered phenolic compound B, 75g of tris(2,4-di-tert-butylphenyl) phosphite, 100g of dioctadecyl thiodipropionate, 40g of hindered amine light stabilizer, and 30g of antioxidant carrier were added sequentially to a high-speed mixer. The stirring paddle was turned on and premixed at 900 rpm for 8 minutes until the materials were evenly dispersed and free of lumps. The premixed material is continuously fed into a twin-screw extruder via a loss-in-weight feeder. The temperatures of each section of the twin-screw extruder are set as follows: feeding section 180℃, compression section 190℃, melting section 200℃, homogenization section 210℃, and die head 220℃. The screw speed is set to 300 rpm. After being melted, mixed, and sheared in the extruder, the material is extruded from the die head and falls into a water tank to cool and solidify into strips. The strips are then cut into granules of approximately 3 mm in length using a pelletizer. The granules are collected and placed in a forced-air drying oven and dried at 62℃ for 5 hours until the moisture content is below 0.1%, yielding the hindered phenolic antioxidant product.

[0047] Example 2 The specific implementation method is the same as in Example 1, except that the modified hindered phenolic compound A is prepared as follows: 120g of 4,6-di-tert-butylresorcinol, 60g of potassium hydroxide, and 350g of N,N-dimethylformamide are added to a reaction vessel, stirred evenly, and heated to 83°C. 170mL of N,N-dimethylformamide solution containing 170g of chloroethylsulfonyl chloride is added dropwise. After the addition is complete, the reaction is maintained at this temperature for 5.5h. Then, the temperature is lowered to 51.5°C, and 220mL of N,N-dimethylformamide solution containing 130g of ethylenediamine is added. The reaction continues for 9.5h. After the reaction is completed, the system is poured into 550mL of ice water to precipitate. The crude product is obtained by filtration, recrystallized three times with ethanol, and dried under vacuum (63°C × 13.5h) to obtain the modified hindered phenolic compound A. Preparation of modified hindered phenolic compound B: 120 g of 2,6-di-tert-butyl-4-methoxyphenol, 200 g of phosphorus oxychloride, and 250 g of toluene were added to a round-bottom flask and refluxed under nitrogen protection for 7.5 h. After the reaction, excess phosphorus oxychloride was removed by vacuum distillation to obtain an intermediate. 130 g of the intermediate and 280 g of tri(octadecyl) phosphite were added to 350 g of tetrahydrofuran and 170 g of pyridine, and the mixture was heated to 73 °C and reacted for 13.5 h. The reaction solution was filtered to remove pyridine hydrochloride, and the filtrate was concentrated under vacuum and purified by column chromatography to obtain modified hindered phenolic compound B. Preparation of hindered phenolic antioxidants: 40g of modified hindered phenolic compound A, 50g of modified hindered phenolic compound B, 85g of tris(2,4-di-tert-butylphenyl) phosphite, 110g of dioctadecyl thiodipropionate, 45g of hindered amine light stabilizer, and 35g of antioxidant carrier were added to a high-speed mixer (950 rpm, premixed for 9 min), transferred to a twin-screw extruder (200℃, screw speed 350 rpm) for melt extrusion, granulation, and drying (63℃ × 5.5 h) to obtain hindered phenolic antioxidants.

[0048] Example 3 The specific implementation method is the same as in Example 1, except that the modified hindered phenolic compound A is prepared as follows: 140g of 4,6-di-tert-butylresorcinol, 70g of potassium hydroxide, and 400g of N,N-dimethylformamide are added to a reaction vessel, stirred evenly, and heated to 84°C. 190mL of N,N-dimethylformamide solution containing 190g of chloroethylsulfonyl chloride is added dropwise, and the reaction is maintained at this temperature for 6h. Then, the temperature is lowered to 52°C, and 240mL of N,N-dimethylformamide solution containing 140g of ethylenediamine is added. The reaction is continued for 10h. After the reaction is completed, the system is poured into 600mL of ice water to precipitate, filtered to obtain the crude product, recrystallized three times with ethanol, and dried under vacuum (64°C × 14h) to obtain the modified hindered phenolic compound A. Preparation of modified hindered phenolic compound B: 140 g of 2,6-di-tert-butyl-4-methoxyphenol, 220 g of phosphorus oxychloride, and 300 g of toluene were added to a round-bottom flask and refluxed under nitrogen protection for 8 h. After the reaction was completed, excess phosphorus oxychloride was removed by vacuum distillation to obtain an intermediate. 140 g of the intermediate and 300 g of tri(octadecyl) phosphite were added to 400 g of tetrahydrofuran and 190 g of pyridine, and the mixture was heated to 74 °C and reacted for 14 h. The reaction solution was filtered to remove pyridine hydrochloride, and the filtrate was concentrated under vacuum and purified by column chromatography to obtain modified hindered phenolic compound B. Preparation of hindered phenolic antioxidants: 50g of modified hindered phenolic compound A, 60g of modified hindered phenolic compound B, 100g of tris(2,4-di-tert-butylphenyl) phosphite, 120g of dioctadecyl thiodipropionate, 50g of hindered amine light stabilizer, and 40g of antioxidant carrier were added to a high-speed mixer (1000 rpm, premixed for 10 min), transferred to a twin-screw extruder (220℃, screw speed 400 rpm) for melt extrusion, granulation, and drying (64℃×6h) to obtain hindered phenolic antioxidants.

[0049] Comparative Example 1 The specific implementation method is the same as in Example 1, except that the preparation of the hindered phenolic antioxidant is as follows: 40g of modified hindered phenolic compound B (excluding modified hindered phenolic compound A), 75g of tris(2,4-di-tert-butylphenyl) phosphite, 100g of dioctadecyl thiodipropionate, 40g of hindered amine light stabilizer, and 30g of antioxidant carrier are added to a high-speed mixer (900 rpm, premixed for 8 min), transferred to a twin-screw extruder (190℃, screw speed 300 rpm) for melt extrusion, granulation, and drying (62℃×5h).

[0050] Comparative Example 2 The specific implementation method is the same as in Example 1, except that the preparation of the hindered phenolic antioxidant is as follows: 30g of modified hindered phenolic compound A (excluding modified hindered phenolic compound B), 75g of tris(2,4-di-tert-butylphenyl) phosphite, 100g of dioctadecyl thiodipropionate, 40g of hindered amine light stabilizer, and 30g of antioxidant carrier are added to a high-speed mixer (900 rpm, premixed for 8 min), transferred to a twin-screw extruder (190°C, screw speed 300 rpm) for melt extrusion, granulation, and drying (62°C × 5 h).

[0051] Comparative Example 3 The specific implementation method is the same as in Example 1, except that the hindered phenolic antioxidant is prepared as follows: 50g of 2,6-di-tert-butyl-p-cresol (replacing modified hindered phenolic compounds A and B), 75g of tris(2,4-di-tert-butylphenyl) phosphite, 100g of dioctadecyl thiodipropionate, 40g of hindered amine light stabilizer, and 30g of antioxidant carrier are added to a high-speed mixer (900 rpm, premixed for 8 min), transferred to a twin-screw extruder (190°C, screw speed 300 rpm) for melt extrusion, granulation, and drying (62°C × 5 h).

[0052] Performance testing The hindered phenolic antioxidants prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance testing according to the following methods: 1. Thermal stability testing was performed using a thermogravimetric analyzer (TA Instruments Q500, accuracy ±0.1mg). Approximately 10mg each of the modified hindered phenolic compounds A and B and the finished antioxidant were placed in an aluminum crucible. The test was conducted under a nitrogen atmosphere (nitrogen flow rate 50mL / min). The heating program was set as follows: initial temperature 50℃, heating to 400℃ at a rate of 10℃ / min. The sample mass change curve with temperature was recorded throughout the process. The 5% thermogravimetric temperature (T5%, i.e., the temperature corresponding to a 5% reduction in sample mass) and the decomposition temperature (Td, the temperature corresponding to the maximum weight loss rate on the thermogravimetric curve) were calculated using analysis software (TA Universal Analysis 2000).

[0053] 2. The specific steps for the migration resistance test are as follows: Add 2.0 wt% of the finished antioxidant to polypropylene (PP, melt flow rate MFR = 2.0 g / 10 min, grade T30S), and mix for 10 min using a Haake torque rheometer (Haake Rheomix OS type, rotor model 28 / 20G, temperature 180℃, speed 100 rpm) to prepare a homogeneous blend; transfer the blend to a flat vulcanizing press (LabTech Electronics HT-200 type, temperature 180℃, pressure 10 MPa) to press it into a 1.0 mm thick flat sample, and cool to room temperature. Cut 50mm × 50mm test pieces; place the test pieces in a 120℃ constant temperature oven for 7 days for aging; immediately after removal, soak the surface of the test pieces in anhydrous ethanol (analytical grade) for 30 seconds; gently wipe the surface adhering substances with qualitative filter paper and collect the wiping liquid in a 10mL volumetric flask; after dilution, use a high performance liquid chromatograph (Agilent 1260, C18 column, mobile phase acetonitrile:water = 70:30, flow rate 1.0mL / min, detection wavelength 275nm) to detect the content of antioxidant components in the wiping liquid; the migration precipitation rate is calculated as: (mass of antioxidant in wiping liquid / initial mass of antioxidant added to the test piece) × 100%.

[0054] 3. The antioxidant efficiency test was performed using a differential scanning calorimeter (DSC, TA Instruments Q2000, accuracy ±0.1mW). The finished antioxidant was added to polyethylene (PE, density 0.92g / cm³, grade 5070) at a dosage of 1.5wt%, and the sample was pressed into a circular disc with a diameter of 10mm and a thickness of 1.0mm using a flat vulcanizing machine (temperature 180℃, pressure 10MPa). The test was conducted under a nitrogen atmosphere (nitrogen flow rate 50mL / min), with the initial temperature set at 120℃. The temperature was increased to 180℃ at a rate of 20℃ / min and held for 5min to eliminate thermal history. Then, the atmosphere was switched to oxygen (oxygen flow rate 50mL / min), and the DSC curve was monitored until a significant oxidation exothermic peak appeared. The oxidation induction period (OIT) was defined as the time from the moment of switching to oxygen to the start of the oxidation exothermic peak (unit: min).

[0055] 4. The synergistic effect test method is as follows: Modified hindered phenolic compound A and tris(2,4-di-tert-butylphenyl) phosphite (168) were compounded in a 1:1 mass ratio to prepare binary compound antioxidant A-168, and modified hindered phenolic compound B and dioctadecyl thiodipropionate (DSTDP) were compounded in a 1:1 mass ratio to prepare binary compound antioxidant B-DSTDP; A-168, B-DSTDP and single components A, B, 168 and DSTDP were added to polypropylene at an addition amount of 1.0 wt%, and the mixing and tableting conditions were the same as those for migration resistance test; the OIT value of each system was determined by DSC oxidation induction period test, and the synergistic factor was calculated by formula: (OIT value of binary compound system) / (average OIT value of single component), where the average OIT value of single component is the arithmetic mean of the OIT values ​​of A and 168, and the arithmetic mean of the OIT values ​​of B and DSTDP.

[0056] 5. Performance test results: Table 1: Performance test results of each embodiment and comparative example Test Project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Modified hindered phenolic compound AT5% (°C) 285 290 295 — — — Modified hindered phenolic compound BT5% (°C) 300 305 310 — — — Antioxidant finished product Td (°C) 265 270 275 240 245 220 Antioxidant migration and leaching rate (%) 0.3 0.25 0.2 1.2 1.0 2.5 Antioxidant finished product OIT (min) 125 130 135 75 80 45 A and 168 co-factors 1.8 1.85 1.9 — — — B and DSTDP synergistic factor 1.7 1.75 1.8 — — — As shown in Table 1, Examples 1-3 effectively solved the problems of easy high-temperature decomposition, poor migration resistance, and weak synergistic effect with auxiliary antioxidants of traditional hindered phenolic antioxidants through structural design and compound optimization of modified hindered phenolic compounds A and B. In terms of thermal stability, the 5% thermal weight loss temperatures (T5%) of modified hindered phenolic compound A in Examples 1-3 were 285℃, 290℃, and 295℃, respectively, and the T5% of compound B were 300℃, 305℃, and 310℃, respectively. These values ​​were significantly higher than the 220℃ decomposition temperature (Td) of the traditional 2,6-di-tert-butyl-p-cresol antioxidant product in Comparative Example 3. This is because the sulfonamide group of compound A forms an intramolecular hydrogen bond network, inhibiting the dehydrogenation decomposition of the phenolic hydroxyl group at high temperatures. The phosphonate group of compound B, through highly reactive phosphorus-oxygen double bonds, slows down the thermal decomposition process, jointly improving the thermal stability of the antioxidant itself and solving the problem of easy decomposition and failure of traditional antioxidants during high-temperature processing. Regarding migration resistance, the migration and precipitation rates of the antioxidant products in Examples 1-3 were only 0.3%, 0.25%, and 0.2%, respectively, which were much lower than those in Comparative Example 1 (1.2%), Comparative Example 2 (1.0%), and Comparative Example 3 (2.5%). This is because the octadecyl chain linked to the phosphonate group of compound B increases the intermolecular entanglement, reduces the thermal motion activity of antioxidant molecules, and reduces their tendency to migrate on the material surface. This effectively avoids the problems of stickiness and performance degradation of products caused by migration and precipitation of traditional antioxidants. In terms of antioxidant efficiency, the oxidation induction period (OIT) of the antioxidant products in Examples 1-3 reached 125 min, 130 min, and 135 min, respectively, which were significantly improved compared with Comparative Example 1 (75 min), Comparative Example 2 (80 min), and Comparative Example 3 (45 min). This is because compound A binds tightly to the polymer matrix through the polar effect of the sulfonamide group, and compound B rapidly captures alkyl free radicals and peroxide free radicals through the phosphonate group. After the two are combined, they form a complementary function with the auxiliary antioxidants (tris(2,4-di-tert-butylphenyl) phosphite and dioctadecyl thiodipropionate) and the hindered amine light stabilizer: "main antioxidant (A / B captures free radicals) - auxiliary stabilizer (168 / DSTDP decomposes peroxides) - photoprotection (HALS inhibits photodegradation)", which significantly enhances the overall antioxidant efficacy and solves the problem of weak synergistic effect in traditional compound systems. In summary, Examples 1-3, through structural innovation and compounding process optimization of two modified hindered phenolic compounds, comprehensively improved the thermal stability, migration resistance, and synergistic effect of antioxidants, effectively overcoming the defects of traditional hindered phenolic antioxidants.

[0057] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A hindered phenolic antioxidant, characterized in that, Including the following parts by weight of raw materials: Modified hindered phenolic compound A: 10-50 parts by weight; Modified hindered phenolic compound B: 20-60 parts by weight; Tris(2,4-di-tert-butylphenyl) phosphite: 50-100 parts by weight; Dioctadecyl thiodipropionate: 80-120 parts by weight; Hindered amine light stabilizer: 30-50 parts by weight; Antioxidant carrier: 20-40 parts by weight; The preparation method of the modified hindered phenolic compound A includes: A1, adding 4,6-di-tert-butylresorcinol, potassium hydroxide and N,N-dimethylformamide to a reaction vessel, stirring evenly, heating to 80-84℃, adding a solution of N,N-dimethylformamide in chloroethylsulfonyl chloride dropwise, and maintaining the temperature for reaction after the addition is complete; A2, then cooling to 50-52℃, adding a solution of N,N-dimethylformamide in ethylenediamine, and continuing the reaction; A3, after the reaction is complete, pouring the system into ice water to precipitate, filtering to obtain the crude product, recrystallizing with ethanol and drying under vacuum.

2. The hindered phenolic antioxidant according to claim 1, characterized in that, In step A1, the heat preservation reaction time is 4-6 hours.

3. The hindered phenolic antioxidant according to claim 1, characterized in that, In step A2, the reaction continues for 8-10 hours.

4. The hindered phenolic antioxidant according to claim 1, characterized in that, In step A3, the ethanol is recrystallized 3-4 times; the vacuum drying temperature is 60-64℃ and the time is 12-14h.

5. The hindered phenolic antioxidant according to claim 1, characterized in that, The preparation method of the modified hindered phenolic compound B includes: B1, adding 2,6-di-tert-butyl-4-methoxyphenol, phosphorus oxychloride and toluene to a round-bottom flask, and reacting under nitrogen protection by reflux; after the reaction is completed, distilling under reduced pressure to obtain 2,6-di-tert-butyl-4-chlorophenoxyphosphorus intermediate; B2, adding the intermediate and tri(octadecyl) phosphite to tetrahydrofuran, adding pyridine, and heating to 70-74℃ to react; filtering the reaction solution to remove pyridine hydrochloride, concentrating the filtrate under reduced pressure and purifying by column chromatography.

6. The hindered phenolic antioxidant according to claim 5, characterized in that, In step B1, the reflux reaction time is 6-8 hours.

7. The hindered phenolic antioxidant according to claim 5, characterized in that, In step B2, the reaction time is 12-14 hours at 70-74℃.

8. A method for preparing a hindered phenolic antioxidant according to any one of claims 1-7, characterized in that, step include: S1. Modified hindered phenolic compound A, modified hindered phenolic compound B, tris(2,4-di-tert-butylphenyl) phosphite, dioctadecyl thiodipropionate, hindered amine light stabilizer, and antioxidant carrier are added to a high-speed mixer for premixing. S2. Transfer to a twin-screw extruder for melt extrusion, granulation, and drying.

9. The preparation method according to claim 8, characterized in that, In step S1, the speed of the high-speed mixer is 800-1000 rpm; the premixing time is 5-10 min.

10. The preparation method according to claim 8, characterized in that, In step S2, the temperature of the twin-screw extruder is 180-220℃, the screw speed is 200-400rpm, the granulation drying temperature is 60-64℃, and the time is 4-6h.