A hindered phenolic antioxidant and a method for its preparation

Abstract

The application discloses a hindered phenolic antioxidant and a preparation method thereof in the field of high polymer material additives, and the antioxidant comprises modified hindered phenolic compound A, modified hindered phenolic compound B, tris(2,4-di-tert-butylphenyl) phosphite, dioctadecyl sulfide dipropionate, hindered amine light stabilizer and an antioxidant carrier. The modified hindered phenolic compound A is prepared from 4,6-di-tert-butyl resorcinol as raw material, which is reacted with chloroethyl sulfonyl chloride in potassium hydroxide and N,N-dimethylformamide, then ethylenediamine is added for continuous reaction, and the product is precipitated by ice water, recrystallized by ethanol and dried in vacuum. The antioxidant is prepared by pre-mixing the components in a high-speed mixer, transferring to a double-screw extruder for melt extrusion, granulation and drying.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polymer material additives, in particular to a hindered phenolic antioxidant and a preparation method thereof. BACKGROUND

[0002] As indispensable stabilizing additives in the processing and long-term use of polymer materials, hindered phenolic antioxidants effectively inhibit the aging degradation of materials caused by heat, oxygen, light and other factors through the capture of free radicals by phenolic hydroxyl groups and the steric hindrance effect of ortho-tert-butyl groups, and are widely used in the fields of plastics, rubbers, chemical fibers and the like. However, the traditional hindered phenolic antioxidant, although having basic antioxidant ability, has significant defects: firstly, in high-temperature processing scenarios, phenolic hydroxyl groups are prone to dehydrogenation or cleavage reactions, resulting in decomposition of the antioxidant itself, not only reducing the protection efficiency, but also possibly releasing small-molecule byproducts to affect material performance; secondly, in the long-term use process, antioxidant molecules migrate to the surface of the material due to thermal motion and gradually precipitate, causing the surface of the product to become sticky, the gloss to decrease, and even the contact medium to be contaminated; thirdly, the synergistic effect of a single hindered phenolic structure and auxiliary antioxidants is limited, making it difficult to cope with multi-factor aging problems in complex environments, thereby limiting its application in high-performance materials.

[0003] In view of the defects of traditional hindered phenolic antioxidants, such as easy decomposition at high temperature, poor migration resistance and insufficient compatibility with polymers, the existing technology mainly improves the comprehensive performance through chemical modification. Some studies attempt to introduce polar groups (such as sulfonamides) at the ortho or para position of the phenolic hydroxyl group to enhance the interfacial bonding between the antioxidant and the polymer through polar interaction, thereby improving the migration resistance; another part of the studies introduces long-chain alkyl groups (such as octadecanol) or rigid heterocyclic structures to increase the steric hindrance of the molecules to delay thermal decomposition, while improving the processing fluidity. For example, the patent with publication number CN113292431B discloses a preparation method of a hindered phenolic antioxidant, which uses 2,6-di-tert-butyl phenol as a raw material, reacts with methyl propiolate in acetonitrile under the catalysis of potassium carbonate to generate an intermediate, and then reacts with octadecanol through a titanium tetraethoxide-catalyzed alkylation reaction to obtain the target product, with a yield of 95%. This method attempts to enhance the migration resistance of the antioxidant by introducing a long-chain alkyl group (octadecanol), while optimizing the molecular structure through alkylation. However, this single functional group modification or simple alkylation modification method still has limitations: the introduction of polar groups (such as sulfonamides) may improve thermal stability, but may cause compatibility with hydrophobic polymers to decrease due to excessive polarity; the introduction of long-chain alkyl groups may enhance migration resistance, but may increase intermolecular entanglement and reduce processing fluidity; and the existing compounding system mainly relies on physical blending, and the components are not uniformly dispersed, the interfacial bonding force between the antioxidant and the polymer is weak, and it is difficult to achieve multiple optimization of thermal stability, migration resistance and synergistic effect, thereby limiting the improvement of overall protection efficiency.

[0004] In the above technical background, it is urgent to develop a new hindered phenolic antioxidant with high thermal stability, low migration and excellent synergistic effect. The present application designs two new structures of modified hindered phenolic compounds, respectively introduces sulfonamide and phosphonate functional groups, utilizes the synergistic effect of steric hindrance, hydrogen bond and free radical capture ability, and combines with optimized compounding process, effectively solves the problems of easy decomposition at high temperature, long-term migration and insufficient synergistic effect of traditional products. The modified hindered phenolic compound A is constructed by grafting reaction of chloroethylsulfonyl chloride and ethylenediamine on the hindered phenolic nucleus to build a steric hindrance structure containing sulfonamide side chain, which not only enhances the intramolecular hydrogen bond to improve the thermal stability, but also reduces the migration tendency through the interaction of polar groups and polymers; the modified hindered phenolic compound B is substituted by phosphonic acid di(octadecyl) ester group on the phenolic hydroxyl group, which utilizes the high reactivity of phosphonate and the steric effect of long chain alkyl to significantly improve the free radical capture efficiency and improve the processing fluidity. Further through high-speed mixing and melt blending process, the components are uniformly dispersed in the polymer matrix to form a synergistic network, and finally a hindered phenolic antioxidant with excellent comprehensive performance is prepared, which provides a new technical solution for high performance and long-term stabilization of high polymer materials. SUMMARY

[0005] The present application aims to provide a hindered phenolic antioxidant and its preparation method, which solves the technical problems of easy decomposition at high temperature, poor migration resistance and weak synergistic effect with auxiliary antioxidants of existing hindered phenolic antioxidants.

[0006] The present application realizes the above-mentioned purpose by the following technical solutions:

[0007] A hindered phenolic antioxidant, comprising the following raw materials by weight:

[0008] Modified hindered phenolic compound A: 10-50 parts by weight;

[0009] Modified hindered phenolic compound B: 20-60 parts by weight;

[0010] Tris(2,4-di-tert-butylphenyl) phosphite: 50-100 parts by weight;

[0011] Dioctadecyl thiodipropionate: 80-120 parts by weight;

[0012] Hindered amine light stabilizer: 30-50 parts by weight;

[0013] Antioxidant carrier: 20-40 parts by weight

[0014] The preparation method of the modified hindered phenol compound A comprises: A1, 4,6-di-tert-butyl resorcinol, potassium hydroxide and N,N-dimethylformamide are added into a reaction kettle, after being uniformly stirred, the temperature is raised to 80-84 DEG C, and the N,N-dimethylformamide solution of chloroethyl sulfonyl chloride is added dropwise, after the dropwise addition is completed, the reaction is preserved; A2, then the temperature is lowered to 50-52 DEG C, the N,N-dimethylformamide solution of ethylenediamine is added, and the reaction is continued; A3, after the reaction is completed, the system is poured into ice water for precipitation, the crude product is obtained by filtration, and is recrystallized by ethanol and vacuum dried.

[0015] In the application, the reaction mechanism of the modified hindered phenol compound A is derived from the chemical modification process of 4,6-di-tert-butyl resorcinol, and the core is to introduce a sulfonamide functional group on the phenolic hydroxyl group through two-step nucleophilic substitution reaction. First, the hydroxyl group in the 4,6-di-tert-butyl resorcinol molecule is dissociated under alkaline conditions (potassium hydroxide) to form a negatively charged oxygen anion, which significantly enhances its nucleophilicity. At this time, the chloroethyl sulfonyl chloride introduced into the reaction system as an electrophile has a high leaving ability because the chlorine atom in the molecule is connected to the sulfur atom with high electronegativity. Under the action of the polar aprotic solvent N,N-dimethylformamide, the oxygen anion attacks the alpha-carbon atom of chloroethyl sulfonyl chloride to form a transition state and finally complete the substitution of the chlorine atom to generate the intermediate product 4,6-di-tert-butyl resorcinol mono (chloroethyl sulfonyl) ether. The key to this step is the activation of the hydroxyl group in the alkaline environment and the stabilization of the reaction transition state by the solvent, which ensures the efficient progress of the substitution reaction. Subsequently, after the reaction system is cooled, ethylenediamine is added, and the amino group (-NH2) in the ethylenediamine molecule acts as a new nucleophile to continue attacking the sulfuryl chloride part in the intermediate product. The sulfur atom in the sulfuryl chloride is in an electron-deficient state due to the connection of two oxygen atoms with high electronegativity, becoming the site of nucleophilic attack. The amino nitrogen atom of ethylenediamine provides a lone pair of electrons to form a new covalent bond with the sulfur atom, while promoting the chlorine atom to be a leaving group to be removed, and finally generating the modified hindered phenol compound A containing a sulfonamide bond (-SO2-NH-). This step not only completes the construction of the sulfonamide side chain, but also forms a hydrogen bond network (the N-H bond of sulfonamide interacts with the O-H bond of the adjacent hydroxyl group) in the molecule by the introduction of the amino group. This hydrogen bond interaction significantly enhances the thermal stability of the compound A, laying a structural foundation for its antioxidant performance in high-temperature processing scenarios.

[0016] According to the preferred embodiment of the application, the 4,6-di-tert-butyl resorcinol is purchased from Jiangsu Lunfeng Synthetic Technology Co., Ltd., and the model number is R-100.

[0017] According to the preferred embodiment of the application, the potassium hydroxide is purchased from Qinghai Salt Lake Industry Co., Ltd., and the model number is industrial grade superior product.

[0018] According to the preferred embodiment of the present application, the N,N-dimethylformamide is purchased from Jiangsu Huachang Chemical Co., Ltd., with the model number of DMF-99.9%.

[0019] According to the preferred embodiment of the present application, the reaction kettle is purchased from Weihai Chemical Machinery Co., Ltd., with the model number of GSH-500L glass-lined reaction kettle.

[0020] According to the preferred embodiment of the present application, the chloroethyl sulfonyl chloride is purchased from Shanghai Maikelin Biochemical Technology Co., Ltd.

[0021] According to the preferred embodiment of the present application, the ethylenediamine is purchased from Jiangsu Feixing Chemical Co., Ltd., with the model number of EDA-industrial grade.

[0022] According to the preferred embodiment of the present application, the ethanol is purchased from COFCO Bio-Technology Co., Ltd., with the model number of food-grade anhydrous ethanol.

[0023] According to the preferred embodiment of the present application, the tris(2,4-di-tert-butylphenyl) phosphite is purchased from Jiangsu Yakc Technology Co., Ltd., with the model number of 168-industrial grade.

[0024] According to the preferred embodiment of the present application, the dioctadecyl sulfide dipropionate is purchased from Jiangsu Hai'an Petrochemical Technology Co., Ltd., with the model number of DSTDP-99%.

[0025] According to the preferred embodiment of the present application, the hindered amine light stabilizer is purchased from Jiangsu Litan Technology Co., Ltd., with the model number of light stabilizer 770.

[0026] According to the preferred embodiment of the present application, the antioxidant carrier is purchased from Sinopec Yangzi Petrochemical Co., Ltd., with the model number of low molecular weight polypropylene PP-2401.

[0027] According to the preferred embodiment of the present application, in step A1, the time for the heat preservation reaction is 4-6h.

[0028] According to the preferred embodiment of the present application, in step A2, the time for the continuous reaction is 8-10h.

[0029] According to the preferred embodiment of the present application, in step A3, the number of times for the ethanol recrystallization is 3-4 times; the temperature for the vacuum drying is 60-64℃, and the time is 12-14h.

[0030] According to the preferred embodiment of the present application, the preparation method of the modified hindered phenol compound B comprises: B1, adding 2,6-di-tert-butyl-4-methoxyphenol, phosphorus oxychloride and toluene into a round-bottom flask, and refluxing under nitrogen protection; after the reaction is completed, vacuum distillation is performed to obtain a 2,6-di-tert-butyl-4-chlorophenoxy phosphorus oxychloride intermediate; B2, adding the intermediate and tris(octadecyl)phosphite into tetrahydrofuran, adding pyridine, and heating to 70-74℃ to react; the reaction solution is filtered to remove pyridine hydrochloride, and the filtrate is concentrated under reduced pressure and then purified by column chromatography.

[0031] In the present application, the reaction mechanism of the modified hindered phenol compound B is based on the phosphorylation reaction, and the core is to introduce the phosphonate group into the phenolic hydroxyl position through two-step substitution reaction. First, the methoxy group (-OCH3) in the 2,6-di-tert-butyl-4-methoxyphenol molecule undergoes phosphorylation reaction under the action of phosphorus pentachloride (POCl3). The phosphorus atom in phosphorus pentachloride has empty d orbitals and strong affinity for oxygen atoms. The oxygen atom of the methoxy group attacks the phosphorus atom as a nucleophilic center, gradually replacing the chlorine atoms on the phosphorus atom, forming an intermediate product 2,6-di-tert-butyl-4-chlorophenoxy phosphorus oxychloride. This step is carried out under toluene refluxing conditions. High temperature promotes the removal of chlorine atoms and the formation of phosphorus-oxygen bond. Vacuum distillation removes excess phosphorus pentachloride by reducing the system pressure, ensuring the purity of the intermediate product. Subsequently, the intermediate product and tris(octadecyl)phosphite undergo phosphorus-oxygen bond exchange reaction in tetrahydrofuran. The phosphorus atom in tris(octadecyl)phosphite molecule is connected with three octadecyloxy groups, which have strong electron-donating ability. The phosphorus atom in the intermediate product is in a high electron-deficient state due to the connection of two chlorine atoms. Under the neutralization of pyridine (as an acid-binding agent), the chlorine atoms of the intermediate product are replaced by the octadecyloxy groups of tris(octadecyl)phosphite, forming a phosphonate di(octadecyl)ester structure. The key to this step is the absorption of hydrogen chloride generated by the acid-binding agent, which avoids the destruction of the phosphorylation product in the acidic environment. At the same time, through the polarity adjustment of the solvent tetrahydrofuran, the nucleophilic substitution reaction is promoted. The finally generated modified hindered phenol compound B significantly enhances the ability to capture free radicals through the high reactivity of the phosphonate group (high phosphorus-oxygen double bond bond energy), while the octadecyl long chain reduces the thermal motion activity of the molecule through the steric hindrance effect, improving the resistance to migration of the antioxidant.

[0032] According to the preferred embodiment of the present application, the 2,6-di-tert-butyl-4-methoxyphenol is purchased from Jiangsu Runfeng Synthetic Technology Co., Ltd., and the model number is RT-264.

[0033] According to the preferred embodiment of the present application, the phosphorus oxychloride is purchased from Jiangsu Feixing Chemical Co., Ltd., and the model number is industrial grade superior product.

[0034] According to the preferred embodiment of the present application, the toluene is purchased from Sinopec Yangzi Petrochemical Co., Ltd., and the model is industrial-grade solvent toluene.

[0035] According to the preferred embodiment of the present application, the round-bottom flask is purchased from Sichuan Shubo (Group) Co., Ltd., and the model is a 5000 mL high borosilicate glass round-bottom flask.

[0036] According to the preferred embodiment of the present application, the nitrogen is purchased from Yingde Gas (Shanghai) Co., Ltd., and the model is high-purity nitrogen (purity ≥ 99.999%).

[0037] According to the preferred embodiment of the present application, the tristearyl phosphite is purchased from Jiangsu Hai'an Petrochemical Technology Co., Ltd., and the model is TMP-18-99%.

[0038] According to the preferred embodiment of the present application, the tetrahydrofuran is purchased from Jiangsu Yida Chemical Co., Ltd., and the model is industrial-grade tetrahydrofuran.

[0039] According to the preferred embodiment of the present application, the pyridine is purchased from Jiangsu Xuzhou Jianping Chemical Co., Ltd., and the model is industrial-grade pyridine (purity ≥ 99.5%).

[0040] According to the preferred embodiment of the present application, the high-speed mixer is purchased from Changzhou Jintan Liangyou Machinery Co., Ltd., and the model is a SHR-1000 high-speed mixer.

[0041] According to the preferred embodiment of the present application, the twin-screw extruder is purchased from Nanjing Keya Chemical Complete Equipment Co., Ltd., and the model is a TE-60 twin-screw extruder.

[0042] According to the preferred embodiment of the present application, in step B1, the reflux reaction time is 6-8 h.

[0043] According to the preferred embodiment of the present application, in step B2, the reaction time at 70-74°C is 12-14 h.

[0044] The present application also provides a preparation method of the hindered phenolic antioxidant, and the steps include:

[0045] S1, the modified hindered phenolic compound A, the modified hindered phenolic compound B, tris (2, 4-di-tert-butyl phenyl) phosphite, dioctadecyl thiodipropionate, hindered amine light stabilizer, antioxidant carrier are added into a high-speed mixer for premixing;

[0046] S2, transfer to a twin-screw extruder for melt extrusion, granulation and drying.

[0047] In the present application, the synergistic mechanism of hindered phenolic antioxidants is reflected in the structural complementarity and functional synergy of multiple components. Modified hindered phenolic compounds A and B act as primary antioxidants, respectively, through the hydrogen bond network of the sulfonamide group and the high reactivity of the phosphonate group to play a core antioxidant role: A delays its thermal decomposition through intramolecular hydrogen bonding, extending the effective protection time; B quickly captures alkyl radicals and peroxide radicals through the phosphonate group to inhibit the transmission of oxidative chain reactions. As an auxiliary antioxidant, tris(2,4-di-tert-butylphenyl) phosphite decomposes hydroperoxide (ROOH) to generate stable alcohol compounds, reducing the source of free radicals, and forms a "free radical capture-peroxide decomposition" double protection chain with the primary antioxidant. The addition of hindered amine light stabilizer provides long-term light protection for the material, and the piperidine ring structure in its molecule can capture excited state radicals induced by ultraviolet light to inhibit the occurrence of photodegradation reactions, and the antioxidant mechanism of hindered phenol is complementary in time dimension (thermal oxidation protection and photooxidation protection). The antioxidant carrier (such as low molecular weight polypropylene) improves the dispersibility of each component by physical blending, and its melt flowability promotes the uniform distribution of antioxidants in the polymer matrix to form a continuous protection network. Each component is tightly combined through intermolecular forces (such as van der Waals force, hydrogen bond) and interfacial interaction, and synergistically plays a role during processing and use, ultimately achieving all-round and long-acting stabilization protection for high polymer materials.

[0048] According to the preferred embodiment of the present application, in step S1, the speed of the high-speed mixer is 800-1000 rpm; the premixing time is 5-10 min.

[0049] According to the preferred embodiment of the present application, in step S2, the temperature of the twin-screw extruder is 180-220℃, and the screw speed is 200-400 rpm; the temperature for granulation and drying is 60-64℃; and the time is 4-6h.

[0050] The present application has the following advantages:

[0051] 1.The hindered phenolic antioxidant of the present application exhibits significant advantages in thermal stability, migration resistance and comprehensive protection efficiency through novel modified structure design and multi-component synergistic compounding. Modified hindered phenolic compound A uses tert-butyl-containing resorcinol as the mother nucleus, and introduces a sulfonamide side chain to form an intramolecular hydrogen bond network, effectively inhibiting the dehydrogenation decomposition reaction of phenolic hydroxyl groups during high-temperature processing. The thermal decomposition temperature of the antioxidant itself is greatly improved, and the antioxidant can maintain structural integrity at higher temperatures, avoiding the failure of protection due to high-temperature decomposition. Modified hindered phenolic compound B replaces the phenolic hydroxyl group with a phosphonate group, which enhances the capture ability of alkyl radicals and peroxy radicals by utilizing the high reactivity of the phosphorus-oxygen double bond. At the same time, the long-chain alkyl structure increases the intermolecular entanglement, significantly reducing the migration tendency of the antioxidant to the material surface, greatly reducing the precipitation amount during long-term use, and solving the problem of product surface stickiness caused by the easy migration of traditional products.

[0052] 2.The synergistic compounding of the two modified hindered phenolic compounds further amplifies the overall protection efficiency. Modified hindered phenolic compound A forms a tight interfacial bond with the polymer matrix through the polar effect of the sulfonamide group, improving the dispersion uniformity of the antioxidant in the material. Modified hindered phenolic compound B constructs a free radical capture network by utilizing the high reactivity of the phosphonate group, and synergistically decomposes hydroperoxide with auxiliary antioxidants to inhibit the propagation of thermal oxidative chain reactions. The addition of hindered amine light stabilizers provides long-term light protection for the material, reducing oxidative degradation induced by ultraviolet light. The antioxidant carrier improves the processing fluidity, allowing the components to disperse more uniformly in the polymer matrix, forming a synergistic network, and ultimately achieving "main antioxidant-auxiliary stabilizer-light protection-processing optimization" multiple protection.

[0053] 3.In practical applications, the antioxidant exhibits good dispersibility and thermal stability during the processing of high molecular materials, effectively reducing the yellowing and degradation of the material during high-temperature processes such as extrusion and injection molding. During long-term use, its low migration property avoids the appearance and performance degradation of the product caused by antioxidant precipitation, significantly extending the service life of the material. Whether it is polyolefin, engineering plastic or rubber, the antioxidant can provide more comprehensive protection to meet the demand for long-term stabilization of high-performance materials. DETAILED DESCRIPTION

[0054] The following detailed description is only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0055] Example 1

[0056] Preparation of modified hindered phenol compound A: 4,6-di-tert-butylresorcinol 100 g, potassium hydroxide 50 g and N,N-dimethylformamide 300 g were added into a reaction kettle, the stirring device was started to stir at 200 rpm for 10 minutes until the material was completely dissolved, then the temperature was raised to 82°C, and a solution of chloroethylsulfonyl chloride 150 g dissolved in 150 mL of N,N-dimethylformamide was slowly added through a constant pressure dropping funnel, the dropping speed was controlled at 5 mL / min, after the addition was completed, the temperature was maintained and the reaction was continued for 5 hours, during which the reaction temperature was recorded every 30 minutes and the stirring speed was adjusted to maintain uniform mixing. After the temperature was lowered to 51°C, a solution of ethylenediamine 120 g dissolved in 200 mL of N,N-dimethylformamide was continuously added through a constant pressure dropping funnel, the dropping speed was 3 mL / min, after the addition was completed, the temperature was maintained at 51°C and the reaction was continued for 9 hours, during which the intermediate product concentration was detected every 1 hour until the reaction was complete. After the reaction was completed, the reaction liquid was slowly poured into a beaker containing 500 mL of ice water, stirred until the precipitation was complete, and then collected by Buchner funnel filtration to obtain the crude product. The crude product was placed in a beaker and 200 mL of ethanol was added, heated to 70°C, stirred and dissolved, then filtered to remove insoluble impurities while hot, and the filtrate was cooled to room temperature to precipitate crystals. The recrystallization operation was repeated 3 times, and finally the crystals were placed in a vacuum drying oven at 62°C, vacuum degree -0.09 MPa, and dried for 13 hours to obtain white powder modified hindered phenol compound A.

[0057] Preparation of modified hindered phenol compound B: 2,6-di-tert-butyl-4-methoxyphenol 100 g, phosphorus oxychloride 180 g and toluene 200 g were added into a round bottom flask, a reflux condenser was installed and nitrogen was introduced to remove air, a magnetic stirrer was started to stir at a speed of 300 rpm, the flask was placed in an oil bath and heated to the reflux temperature of toluene (about 110°C), and the reflux reaction was maintained for 7 hours. During the reaction, 5 mL of nitrogen was added every hour to maintain an oxygen-free environment. After the reflux was completed, the oil bath was turned off and the flask was cooled to 80°C. The excess phosphorus oxychloride was distilled at -0.08 MPa and 60°C using a vacuum distillation device. The remaining liquid was collected as the intermediate 2,6-di-tert-butyl-4-chlorophenoxyphosphorus trichloride. The intermediate 120 g and tris(octadecyl) phosphite 250 g were added to 500 mL of tetrahydrofuran, stirred and dissolved, and then pyridine 150 g 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. The dropwise addition was controlled at a rate of 10 mL / min. After the dropwise addition was completed, the temperature was maintained at 72°C for 13 hours to continue the reaction. A water bath was used to maintain the temperature during the reaction. After the reaction was completed, the mixture was filtered, the filter cake was washed twice with 50 mL of tetrahydrofuran, and the filtrate and wash were combined and concentrated under reduced pressure to remove the tetrahydrofuran solvent. The remaining concentrate was purified by silica gel column chromatography using a mixture of petroleum ether and ethyl acetate (10:1 by volume) as the eluent. The target fraction was collected and the eluent was removed by rotary evaporation to obtain modified hindered phenol compound B as a yellow viscous liquid.

[0058] Preparation of hindered phenolic antioxidant: Modified hindered phenol compound A 30 g, modified hindered phenol compound B 40 g, tris(2,4-di-tert-butylphenyl) phosphite 75 g, dioctadecyl thiodipropionate 100 g, hindered amine light stabilizer 40 g, and antioxidant carrier 30 g were sequentially added to a high-speed mixer, the stirring paddle was started at a speed of 900 rpm for 8 minutes of pre-mixing, and the materials were uniformly dispersed without clumping. The pre-mixed material was continuously added to a twin-screw extruder through a loss-in-weight feeder. The temperature settings for each section of the twin-screw extruder were as follows: feed section 180°C, compression section 190°C, melting section 200°C, homogenization section 210°C, and die head 220°C. The screw speed was set at 300 rpm. The material was extruded from the die head of the extruder after melting, mixing, and shearing, and fell into a water tank to solidify into a strip. The strip was cut into particles with a length of about 3 mm using a pelletizer, and the particles were collected and placed in a forced air drying oven at 62°C for 5 hours to reduce the moisture content to less than 0.1%. The hindered phenolic antioxidant was obtained as a finished product.

[0059] Example 2

[0060] The specific implementation is the same as example 1, except that the preparation of modified hindered phenol compound A: 4, 6-di-tert-butyl resorcinol 120 g, potassium hydroxide 60 g and N, N-dimethylformamide 350 g are added into a reaction kettle, after stirring uniformly, the temperature is raised to 83℃, and a solution of chloroethylsulfonyl chloride 170 g in N, N-dimethylformamide 170 mL is added dropwise, after the dropwise addition is completed, the reaction is maintained for 5.5 h; then the temperature is lowered to 51.5℃, and a solution of ethylenediamine 130 g in N, N-dimethylformamide 220 mL is added, and the reaction is continued for 9.5 h; after the reaction is completed, the system is poured into ice water 550 mL for precipitation, and the crude product is obtained by filtration, and is recrystallized with ethanol for 3 times, and vacuum dried (63℃×13.5 h) to obtain modified hindered phenol compound A. The preparation of modified hindered phenol compound B: 2, 6-di-tert-butyl-4-methoxyphenol 120 g, phosphorus oxychloride 200 g and toluene 250 g are added into a round-bottom flask, and the reaction is carried out under reflux for 7.5 h under nitrogen protection; after the reaction is completed, the excess phosphorus oxychloride is removed by distillation under reduced pressure to obtain an intermediate; the intermediate 130 g and tris (octadecyl) phosphite 280 g are added into tetrahydrofuran 350 g, pyridine 170 g is added, and the reaction is carried out at 73℃ for 13.5 h; the reaction liquid is filtered to remove pyridine hydrochloride, and the filtrate is concentrated under reduced pressure and then purified by column chromatography to obtain modified hindered phenol compound B. The preparation of hindered phenolic antioxidant: modified hindered phenol compound A 40 g, modified hindered phenol compound B 50 g, tris (2, 4-di-tert-butylphenyl) phosphite 85 g, dioctadecyl thiodipropionate 110 g, hindered amine light stabilizer 45 g, antioxidant carrier 35 g are added into a high-speed mixer (rotation speed 950 rpm, pre-mixing 9 min), and then transferred into a twin-screw extruder (temperature 200℃, screw rotation speed 350 rpm) for melt extrusion, granulation and drying (63℃×5.5 h) to obtain the hindered phenolic antioxidant.

[0061] Example 3

[0062] The specific implementation is the same as example 1, except that the preparation of the modified hindered phenol compound A: 4,6-di-tert-butyl resorcinol 140 g, potassium hydroxide 70 g and N,N-dimethylformamide 400 g are added to a reaction kettle, stirred uniformly, and then heated to 84°C. A solution of chloroethylsulfonyl chloride 190 g in N,N-dimethylformamide 190 mL is added dropwise, and after the addition is completed, the reaction is maintained for 6 h. Then, the temperature is lowered to 52°C, and a solution of ethylenediamine 140 g in N,N-dimethylformamide 240 mL is added, and the reaction is continued for 10 h. After the reaction is completed, the system is poured into ice water 600 mL for precipitation, and the crude product is obtained by filtration, and then recrystallized from ethanol for 3 times, and vacuum dried (64°C x 14 h) to obtain the modified hindered phenol compound A. The preparation of the modified hindered phenol compound B: 2,6-di-tert-butyl-4-methoxyphenol 140 g, phosphorus oxychloride 220 g and toluene 300 g are added to a round-bottom flask, and the reaction is carried out under reflux for 8 h under nitrogen protection. After the reaction is completed, the excess phosphorus oxychloride is removed by distillation under reduced pressure to obtain an intermediate. The intermediate 140 g and tris(octadecyl) phosphite 300 g are added to tetrahydrofuran 400 g, pyridine 190 g is added, and the reaction is carried out at 74°C for 14 h. The reaction liquid is filtered to remove pyridine hydrochloride, and the filtrate is concentrated under reduced pressure and then purified by column chromatography to obtain the modified hindered phenol compound B. The preparation of the hindered phenolic antioxidant: the modified hindered phenol compound A 50 g, the modified hindered phenol compound B 60 g, tris(2,4-di-tert-butylphenyl) phosphite 100 g, dioctadecyl thiodipropionate 120 g, hindered amine light stabilizer 50 g, and antioxidant carrier 40 g are added to a high-speed mixer (rotation speed 1000 rpm, pre-mixing 10 min), transferred to a twin-screw extruder (temperature 220°C, screw rotation speed 400 rpm) for melt extrusion, and then granulated and dried (64°C x 6 h) to obtain the hindered phenolic antioxidant.

[0063] Comparative example 1

[0064] The specific implementation is the same as example 1, except that the preparation of the hindered phenolic antioxidant: the modified hindered phenol compound B 40 g (without the modified hindered phenol compound A), tris(2,4-di-tert-butylphenyl) phosphite 75 g, dioctadecyl thiodipropionate 100 g, hindered amine light stabilizer 40 g, and antioxidant carrier 30 g are added to a high-speed mixer (rotation speed 900 rpm, pre-mixing 8 min), transferred to a twin-screw extruder (temperature 190°C, screw rotation speed 300 rpm) for melt extrusion, and then granulated and dried (62°C x 5 h).

[0065] Comparative example 2

[0066] The specific implementation is the same as Example 1, except that the preparation of the hindered phenolic antioxidant: modified hindered phenolic compound A 30 g (not containing modified hindered phenolic compound B), tris (2, 4-di-tert-butylphenyl) phosphite 75 g, dioctylthiodipropionate 100 g, hindered amine light stabilizer 40 g, antioxidant carrier 30 g are added into a high-speed mixer (speed 900 rpm, premixing 8 min), transferred to a twin-screw extruder (temperature 190°C, screw speed 300 rpm) for melt extrusion, and granulated and dried (62°C x 5h).

[0067] Comparative Example 3

[0068] The specific implementation is the same as Example 1, except that the preparation of the hindered phenolic antioxidant: modified hindered phenolic compound A 30 g (not containing modified hindered phenolic compound B), tris (2, 4-di-tert-butylphenyl) phosphite 75 g, dioctylthiodipropionate 100 g, hindered amine light stabilizer 40 g, antioxidant carrier 30 g are added into a high-speed mixer (speed 900 rpm, premixing 8 min), transferred to a twin-screw extruder (temperature 190°C, screw speed 300 rpm) for melt extrusion, and granulated and dried (62°C x 5h).

[0069] Performance test

[0070] The hindered phenolic antioxidants prepared in Examples 1-3 and Comparative Examples 1-3 above are subjected to performance tests according to the following methods:

[0071] 1. Thermal stability test: A thermogravimetric analyzer (TA Instruments Q500 type, accuracy ±0.1 mg) is used, and about 10 mg of modified hindered phenolic compound A, B and antioxidant finished product are placed in an aluminum crucible. The test is carried out under nitrogen atmosphere (nitrogen flow 50 mL / min), and the temperature program is set as follows: initial temperature 50°C, heating rate 10°C / min to 400°C, and the sample mass change with temperature curve is recorded throughout the test. The 5% thermal weight loss temperature (T5%, i.e. the temperature corresponding to a 5% reduction in sample mass) and decomposition temperature (Td, the temperature corresponding to the maximum weight loss rate on the thermogravimetric curve) are calculated by analysis software (TA Universal Analysis 2000).

[0072] 2. The specific steps of the migration resistance test are as follows: the antioxidant product is added into polypropylene (PP, melt flow rate MFR = 2.0 g / 10 min, grade T30S) at an addition amount of 2.0 wt%, and a Haake torque rheometer (Haake Rheomix OS type, rotor type 28 / 20G, temperature 180°C, rotation speed 100 rpm) is used to mix for 10 min to prepare a uniform blend; the blend is transferred to a flat vulcanizing machine (LabTech Electronics HT-200 type, temperature 180°C, pressure 10 MPa) to press into a flat sample with a thickness of 1.0 mm, and after cooling to room temperature, a 50 mm x 50 mm test piece is cut; the test piece is placed in a constant temperature oven at 120°C for aging for 7 days, and immediately after taking out, the surface of the test piece is immersed in anhydrous ethanol (analytical pure) for 30 seconds, the surface attachments are gently wiped with qualitative filter paper, and the wiping liquid is collected in a 10 mL volumetric flask, and after constant volume, the content of the antioxidant component in the wiping liquid is detected by high performance liquid chromatography (Agilent 1260 type, C18 chromatographic column, mobile phase is acetonitrile: water = 70:30, flow rate 1.0 mL / min, detection wavelength 275 nm); the migration extraction rate calculation formula is: (the mass of the antioxidant in the wiping liquid / the initial added antioxidant mass in the test piece) x 100%.

[0073] 3. The antioxidant efficiency test uses a differential scanning calorimeter (DSC, TA Instruments Q2000 type, accuracy ± 0.1 mW), the antioxidant product is added into polyethylene (PE, density 0.92 g / cm³, grade 5070) at an addition amount of 1.5 wt%, and a flat vulcanizing machine (temperature 180°C, pressure 10 MPa) is used to press into a round test piece with a diameter of 10 mm and a thickness of 1.0 mm; the test is carried out under a nitrogen atmosphere (nitrogen flow rate 50 mL / min), the initial temperature is set to 120°C, and the temperature is raised to 180°C at a rate of 20°C / min and kept for 5 min to eliminate the thermal history; then the oxygen atmosphere is switched (oxygen flow rate 50 mL / min), and the DSC curve is continuously monitored until the obvious oxidation exothermic peak appears; the oxidation induction time (OIT) is defined as the time (unit: min) from the time when the oxygen is switched to the starting point of the oxidation exothermic peak.

[0074] 4. Synergistic effect test method: modified hindered phenolic compound A and tris(2,4-di-tert-butylphenyl) phosphite (168) were compounded to prepare binary antioxidant A-168 at a mass ratio of 1:1, and modified hindered phenolic compound B and dilauryl thiodipropionate (DSTDP) were compounded to prepare binary antioxidant B-DSTDP at a mass ratio of 1:1; 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 tabletting conditions were the same as those in the migration resistance test; the OIT values of each system were determined by DSC oxidation induction period test, and the synergistic factor calculation formula was: (binary compound system OIT value) / (single component OIT average value), wherein the single component OIT average value was the arithmetic average of the OIT values of A and 168, and the arithmetic average of the OIT values of B and DSTDP.

[0075] 5. Performance test results:

[0076] Table 1: Performance test results of each example and comparative example

[0077] Test item Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Modified hindered phenol compound AT5% (°C) 285 290 295 — — — Modified hindered phenol compound BT5% (°C) 300 305 310 — — — Antioxidant finished product Td (°C) 265 270 275 240 245 220 Antioxidant finished product migration and separation rate (%) 0.3 0.25 0.2 1.2 1.0 2.5 Antioxidant finished product OIT (min) 125 130 135 75 80 45 Synergistic factor of A with 168 1.8 1.85 1.9 — — — Synergistic factor of B with DSTDP 1.7 1.75 1.8 — — —

[0078] As can be seen from Table 1, by structural design and compounding optimization of modified hindered phenolic compounds A and B, examples 1-3 effectively solve the problems of high temperature decomposition, poor migration resistance and weak synergistic effect of traditional hindered phenolic antioxidants. In terms of thermal stability, the 5% thermal weight loss temperature (T5%) of modified hindered phenolic compound A in examples 1-3 is 285°C, 290°C and 295°C respectively, and the T5% of compound B is 300°C, 305°C and 310°C respectively, which are significantly higher than the decomposition temperature (Td) of 220°C of 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, which inhibits the dehydrogenation decomposition of phenolic hydroxyl group at high temperature, and the phosphonate group of compound B delays the thermal decomposition process through the high reactivity of phosphorus-oxygen double bond, which improves the thermal stability of the antioxidant itself and solves the problem of easy decomposition of traditional antioxidants at high temperature. In terms of migration resistance, the migration and precipitation rate of antioxidant products in examples 1-3 is only 0.3%, 0.25% and 0.2%, which is far lower than that of comparative example 1 (1.2%), comparative example 2 (1.0%) and comparative example 3 (2.5%). This is because the phosphonate group of compound B is connected with long-chain octadecyl, which increases the intermolecular entanglement and reduces the thermal motion activity of antioxidant molecules, thereby reducing the migration tendency of the antioxidant on the material surface and effectively avoiding the problem of sticky surface and performance degradation of the product caused by migration and precipitation of traditional antioxidants. In terms of antioxidant efficiency, the oxidation induction time (OIT) of antioxidant products in examples 1-3 is 125 min, 130 min and 135 min respectively, which is significantly higher than that of comparative example 1 (75 min), comparative example 2 (80 min) and comparative example 3 (45 min). This is because compound A is tightly combined with the polymer matrix through the polar effect of sulfonamide group, and compound B quickly captures alkyl radicals and peroxide radicals through the phosphonate group. After compounding, a synergistic network of "main antioxidant (A / B capturing free radicals) - auxiliary stabilization (168 / DSTDP decomposing peroxide) - light protection (HALS inhibiting photodegradation)" is formed with auxiliary antioxidants (tris(2,4-di-tert-butylphenyl) phosphite, dioctadecyl thiodipropionate) and hindered amine light stabilizer, which significantly enhances the overall antioxidant efficiency and solves the problem of weak synergistic effect of traditional compounding system. In summary, examples 1-3 improve the thermal stability, migration resistance and synergistic effect of antioxidants by structural innovation and compounding process optimization of two modified hindered phenolic compounds, which effectively overcome the defects of traditional hindered phenolic antioxidants.

[0079] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the patent scope of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are within the protection scope of the present application.

Claims

1. A hindered phenolic antioxidant characterized in that, The raw materials include the following weight parts: Modified hindered phenol compound A: 10-50 parts by weight; Modified hindered phenol compound B: 20-60 parts by weight; Tris (2, 4-di-tert-butylphenyl) phosphite: 50-100 parts by weight; Dialkylthiodipropionate: 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 phenol compound A comprises: A1, adding 4, 6-di-tert-butyl resorcinol, potassium hydroxide and N, N-dimethylformamide into a reaction kettle, stirring uniformly, and then heating to 80-84℃, and then adding dropwise a solution of chloroethylsulfonyl chloride in N, N-dimethylformamide, and then keeping warm after dropwise addition is completed; A2, then cooling to 50-52℃, adding a solution of ethylenediamine in N, N-dimethylformamide, and continuing to react; A3, after the reaction is completed, pouring the system into ice water to precipitate, filtering to obtain a crude product, recrystallizing with ethanol, and vacuum drying; The preparation method of the modified hindered phenol compound B comprises: B1, adding 2, 6-di-tert-butyl-4-methoxyphenol, phosphorus oxychloride and toluene into a round-bottom flask, and refluxing under nitrogen protection; after the reaction is completed, distillation under reduced pressure is performed to obtain a 2, 6-di-tert-butyl-4-chlorophenoxyphosphorus trichloride intermediate; B2, adding the intermediate and tristearyl phosphite into tetrahydrofuran, adding pyridine, and heating to 70-74℃ to react; filtering the reaction solution to remove pyridine hydrochloride, and then concentrating the filtrate under reduced pressure and purifying by column chromatography.

2. The hindered phenolic antioxidant according to claim 1, characterized in that, In step A1, the time for keeping warm is 4-6h.

3. The hindered phenolic antioxidant according to claim 1, wherein In step A2, the time for continuing to react is 8-10h.

4. The hindered phenolic antioxidant according to claim 1, wherein In step A3, the recrystallization with ethanol is performed for 3-4 times; the temperature for vacuum drying is 60-64℃, and the time is 12-14h.

5. The hindered phenolic antioxidant according to claim 1, wherein In step B1, the time for refluxing is 6-8h.

6. The hindered phenolic antioxidant of claim 1, wherein In step B2, the time for reacting at 70-74℃ is 12-14h.

7. A process for the preparation of a hindered phenolic antioxidant according to any one of claims 1 to 6, characterized by the steps of Comprise: S1, adding the modified hindered phenol compound A, the modified hindered phenol compound B, tris (2, 4-di-tert-butylphenyl) phosphite, dialkylthiodipropionate, hindered amine light stabilizer and antioxidant carrier into a high-speed mixer for premixing; S2, transferring to a twin-screw extruder for melt extrusion, granulation and drying.

8. The preparation method according to claim 7, characterized in that, In step S1, the rotating speed of the high-speed mixer is 800-1000rpm; and the premixing time is 5-10min.

9. The preparation method according to claim 7, characterized in that, In step S2, the temperature of the twin-screw extruder is 180-220℃, the screw rotating speed is 200-400rpm; the temperature for granulation and drying is 60-64℃; and the time is 4-6h.