An antioxidant and a method for preparing the same

Abstract

This invention belongs to the field of fine chemical technology, and particularly relates to an antioxidant and its preparation method. The antioxidant, by weight, comprises the following components: 30-60 parts of a primary antioxidant, 8-20 parts of a secondary antioxidant, 5-15 parts of modified tannic acid, 10-15 parts of a nucleating agent, and 15-20 parts of a lubricant; the primary antioxidant is a hindered phenolic antioxidant, and the secondary antioxidant is a thioester or phosphite antioxidant. This invention, by compounding modified tannic acid with common polymer antioxidants, can improve the oxidation induction period of polymers and significantly reduce their yellow index, further expanding the application of tannic acid in the field of polymer antioxidants.

Description

Technical Field

[0001] This invention belongs to the field of fine chemical technology, and in particular relates to an antioxidant and its preparation method. Background Technology

[0002] Antioxidants are used to inhibit the oxidative degradation of polymers during manufacturing, processing, and use, and their demand increases with the expansion of rubber and plastics production scale. Currently commonly used antioxidants include hindered phenols (such as 1010 and 1076), phosphites (such as 168 and 626), and thioethers (such as DSTDP and DLTDP), which are widely praised and in high demand. However, as the polymer processing industry pursues high-performance and high-value-added products, the requirements for antioxidant protection and color improvement in resin processing are increasing, highlighting the advantages and disadvantages of single antioxidants. Given the difficulty in developing new antioxidants, compounding existing products to improve their effectiveness has become a research hotspot in recent years.

[0003] CN106336526A discloses a composite antioxidant. This patent adds color powder to the antioxidant and then adds it during polymer processing. Only a small amount of color powder is needed to achieve long-term protection of the polymer material's color. CN104356507A discloses a hindered phenolic polypropylene composite antioxidant. The main antioxidant includes N,N-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hexanediamine, α-vitamin E, and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; the auxiliary antioxidant is tris(2,4-di-tert-butylphenyl) phosphite. This composite antioxidant can better meet the comprehensive performance requirements of polypropylene, improving antioxidant performance and reducing costs.

[0004] Existing technologies disclose methods for adjusting the yellow index of antioxidants using colorants and the antioxidant effect of tannic acid in the polymer field. However, the natural color of tannic acid affects its effectiveness as an antioxidant in optimizing the color index of polymers. Therefore, there is an urgent need to develop an antioxidant that includes modified tannic acid, thereby reducing the influence of tannic acid's own color on polymer color and expanding the application areas of tannic acid as an oxidant. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, one of the objectives of this invention is to provide an antioxidant that has good color stability and antioxidant properties.

[0006] One of the objectives of this invention is achieved through the following technical solution:

[0007] An antioxidant, by weight, comprises the following components: 30-60 parts of primary antioxidant, 8-20 parts of secondary antioxidant, 5-15 parts of modified tannic acid, 10-15 parts of nucleating agent, and 15-20 parts of lubricant.

[0008] The primary antioxidant is a hindered phenolic antioxidant, and the secondary antioxidant is a thioester or phosphite antioxidant.

[0009] The preparation process of the modified tannic acid includes the following steps:

[0010] (1) Add 4-hydroxy-7-N,N-diethylaminocoumarin, malononitrile, p-nitrobenzaldehyde and potassium hydrogen phthalate to water, react at 50-70℃ for 5-7h, and then treat to obtain intermediate 1.

[0011] (2) Intermediate 1 and N,N-dimethylformamide dimethyl acetal were mixed and reacted at 105-115℃ for 20-40 min, and then processed to obtain intermediate 2.

[0012] (3) Intermediate 2 and iron powder were added to acetic acid and reacted for 12-18 hours. After processing, intermediate 3 was obtained.

[0013] (4) Add intermediates 3,4-fluoro-3-aldehyde phenylboronic acid and magnesium sulfate to dichloromethane, react for 8-16 hours and then process to obtain tannic acid modifier.

[0014] (5) Add tannic acid modifier, tannic acid and magnesium sulfate to water and stir at room temperature for 12-16 hours to obtain the modified tannic acid.

[0015] The principle of this invention for preparing modified tannic acid is as follows: First, 4-hydroxy-7-N,N-diethylaminocoumarin, malononitrile, p-nitrobenzaldehyde, and potassium hydrogen phthalate are reacted with Knoevenagel to obtain intermediate 1; then, DMF-DMA is used as a formylation agent to react with the primary amine of intermediate 1 to generate the corresponding amidine compound, i.e., intermediate 2; then, intermediate 2 is reduced to an amino group by iron powder under acidic conditions to obtain intermediate 3; next, the amino group of intermediate 3 reacts with the aldehyde group of 4-fluoro-3-aldehydephenylboronic acid to obtain a Schiff base, i.e., a tannic acid modifier; finally, the active functional group boric acid of the tannic acid modifier and the active functional group phenolic hydroxyl group of tannic acid can generate modified tannic acid under relatively mild reaction conditions.

[0016] Further, the molar ratio of 4-hydroxy-7-N,N-diethylaminocoumarin, malononitrile, p-nitrobenzaldehyde and potassium hydrogen phthalate in step (1) is 1:(1~1.2):(1~1.2):(0.98~1).

[0017] Further, the molar ratio of intermediate 1 and N,N-dimethylformamide dimethyl acetal in step (2) is 1:(65-75).

[0018] Further, the molar ratio of intermediate 2 and iron powder in step (3) is 1:(15-18).

[0019] Further, the molar ratio of intermediate 3,4-fluoro-3-aldehyde phenylboronic acid and magnesium sulfate in step (4) is 1:(1~1.2):(0.02~0.04).

[0020] Further, the molar ratio of tannic acid, tannic acid modifier, and magnesium sulfate in step (5) is 1:(4.1-4.5):(4.2-4.5).

[0021] Furthermore, the hindered phenolic antioxidant is one of antioxidant 1010, antioxidant 1076 and antioxidant 736; the thioester is one of antioxidant DLTDP and antioxidant DTPDP; and the phosphite antioxidant is antioxidant 618.

[0022] Furthermore, the nucleating agent is one of HPN-20E and nucleating agent 713; the lubricant is selected from one of zinc stearate and calcium stearate.

[0023] The second objective of this invention is to provide a method for preparing an antioxidant.

[0024] The second objective of this invention is achieved by the following technical solution:

[0025] The preparation method of the above antioxidant includes the following steps: adding the main antioxidant, auxiliary antioxidant, modified tannic acid, nucleating agent and lubricant into a kneader and stirring for 30 minutes, then heating to 130-150°C and continuing to stir for 45-60 minutes. After the mixing is completed, the mixture is cooled to 20-45°C and granulated to obtain the antioxidant.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] This invention improves the oxidation induction period of polymers by combining modified tannic acid with common polymer antioxidants. At the same time, the modified tannic acid can reduce the influence of tannic acid's own color on the polymer color, significantly reducing its yellow index, thus further expanding the application of tannic acid in the field of polymer antioxidants. Attached Figure Description

[0028] Figure 1 This is a flowchart illustrating the preparation process of the modified tannic acid of this invention.

[0029] Figure 2 This is an IR schematic diagram of the modified tannic acid of this invention. Detailed Implementation

[0030] The present invention will now be further described with reference to the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. Specific conditions not specified in the embodiments are performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, all reagents or instruments used are conventional products obtained through commercial channels.

[0031] Example 1

[0032] An antioxidant, by weight, comprises the following components: 45 parts antioxidant 1010, 15 parts antioxidant 618, 8 parts modified tannic acid, 12 parts nucleating agent 713, and 17 parts zinc stearate.

[0033] The preparation process of the modified tannic acid is as follows: Figure 1 As shown, it includes the following steps:

[0034] (1) Add 0.1 mol of 4-hydroxy-7-N,N-diethylaminocoumarin, 0.1 mol of malononitrile, 0.1 mol of p-nitrobenzaldehyde, and 98 mmol of potassium hydrogen phthalate (KHP) to 150 mL of deionized water, stir well, and then heat to 50 °C for 6 h. After cooling the reaction solution to room temperature, filter, collect the filter cake (wash the filter cake with deionized water during filtration), dry it, and then slurry it with a mixed solvent (1 g filter cake: 3 mL mixed solvent, V 氯仿 V 乙醇 =1:2) to obtain intermediate 1.

[0035] (2) Take intermediate 1 (0.1 mol) and N,N-dimethylformamide dimethyl acetal (DMF-DMA, 7 mol) and react at 110℃ for 30 min; filter the reaction solution and collect the filter cake. During the filtration process, wash the filter cake with ethanol and dry it. Dissolve the filter cake with chloroform and then precipitate the solid from the chloroform solution with ethanol to obtain intermediate 2.

[0036] (3) Add 0.05 mol of intermediate 2 to 100 mL of acetic acid, then add 0.8 mol of iron powder and react at 25 °C for 16 h. Filter the reaction solution using Celite (washing the filter cake with ethyl acetate during filtration), collect the filtrate, concentrate it, dilute the concentrate with water, extract the aqueous phase with ethyl acetate, wash the ethyl acetate phase with saturated brine, dry the ethyl acetate phase with sodium sulfate, concentrate, and pass it through a column (eluent: petroleum ether: ethyl acetate = 10:1) to obtain intermediate 3. MS results for intermediate 3: [M+H] + m / z: 458.21, ESI-MS (m / z): 458.23.

[0037] (4) Take intermediate 3 (0.1 mol), 4-fluoro-3-aldehyde phenylboronic acid (0.11 mol), and magnesium sulfate (3 mmol) and add them to 200 mL of dichloromethane and react at 28 °C for 12 h. The reaction solution is dried, concentrated, and column filtered (1 wt% acetic acid is added to the eluent, and the eluent is petroleum ether: ethyl acetate = 7:1) to obtain tannic acid modifier.

[0038] MS results for tannic acid modifier: [M+H] + m / z: 608.24, ESI-MS (m / z): 608.25; NMR results of tannic acid modifier: 1 H NMR (C 33 H 31 BFN5O5, 400MHz, DMSO-d6): δ8.69 (d, 2H), 7.78 (m, 1H), 7.65 (d, 1H), 7.42 (m, 1H), 7.38 (m, 3H), 7.15 (m, 1H), 6.93 (m, 1H), 6.68 (m, 1H), 6.49 (s, 1H), 4.25 (s, 1H), 3.36 (q, 4H), 2.99 (s, 6H), 1.12 (t, 6H).

[0039] (5) Add tannic acid modifier (42 mmol) and tannic acid (10 mmol) to a mixed solvent of 150 mL THF and 3 mL water, stir for 20 min, then add magnesium sulfate (43 mmol) and stir at room temperature for 14 h; after concentrating the reaction solution, dilute the concentrate with ethanol, and dialyze through a dialysis bag (molecular weight cutoff 3000D) to remove impurities with molecular weight below 3000D. After concentrating and drying the solution in the dialysis bag, modified tannic acid is obtained.

[0040] The IR results of the above modified tannic acid are as follows: Figure 2 As shown: Compared to tannic acid, the absorption at the phenolic hydroxyl group of modified tannic acid (3600-3200 cm⁻¹) is higher. -1 The intensity decreased somewhat, and it was at 2240cm. -1 The presence of a cyano group (from the tannic acid modifier) ​​characteristic peak indicates that the present invention successfully prepared modified tannic acid.

[0041] This embodiment also provides a method for preparing the above-mentioned antioxidant, the process including the following steps:

[0042] Antioxidant 1010, antioxidant 618, modified tannic acid, nucleating agent 713 and zinc stearate are added to a kneader and stirred for 30 minutes. The temperature is then raised to 140°C and stirred for another 52 minutes. After the mixing is completed, the mixture is transferred to a storage tank through an insulated pipe. After cooling to 25°C, it is transported to a granulator for granulation to obtain the antioxidant.

[0043] Example 2

[0044] An antioxidant, by weight, comprises the following components: 30 parts antioxidant 1076, 8 parts antioxidant DLTDP, 5 parts modified tannic acid, 10 parts nucleating agent HPN-20E, and 15 parts calcium stearate.

[0045] The preparation process of the modified tannic acid includes the following steps:

[0046] (1) Add 0.1 mol of 4-hydroxy-7-N,N-diethylaminocoumarin, 0.11 mol of malononitrile, 0.11 mol of p-nitrobenzaldehyde, and 99 mmol of potassium hydrogen phthalate (KHP) to 150 mL of deionized water, stir well, and then heat to 70 °C for 5 h. After cooling the reaction solution to room temperature, filter, collect the filter cake (wash the filter cake with deionized water during filtration), dry it, and then slurry it with a mixed solvent (1 g filter cake: 3 mL mixed solvent, V 氯仿 V 乙醇 =1:2) to obtain intermediate 1;

[0047] (2) Take intermediate 1 (0.1 mol) and N,N-dimethylformamide dimethyl acetal (7.5 mol) and react at 105℃ for 40 min; filter the reaction solution and collect the filter cake. During the filtration process, wash the filter cake with ethanol, dry it and recrystallize it with a mixed solvent (dissolve the filter cake with chloroform and then precipitate the solid from the chloroform solution with ethanol) to obtain intermediate 2.

[0048] (3) 0.05 mol of intermediate 2 was added to 100 mL of acetic acid, followed by 0.75 mol of iron powder. The mixture was reacted at 23 °C for 18 h. The reaction solution was filtered through a Celite filter (the filter cake was washed with ethyl acetate during filtration). The filtrate was collected, concentrated, and diluted with water. The aqueous phase was extracted with ethyl acetate, and the ethyl acetate phase was washed with saturated brine. The ethyl acetate phase was dried with sodium sulfate, concentrated, and subjected to column chromatography (eluent: petroleum ether: ethyl acetate = 10:1) to obtain intermediate 3. The MS results of intermediate 3 in this example were consistent with those shown in Example 1.

[0049] (4) Intermediate 3 (0.1 mol), 4-fluoro-3-aldehyde phenylboronic acid (0.12 mol), and magnesium sulfate (2 mmol) were added to 200 mL of dichloromethane and reacted at 25 °C for 16 h. The reaction solution was dried, concentrated, and column chromatography (1 wt% acetic acid was added to the eluent, and the eluent was petroleum ether: ethyl acetate = 7:1) to obtain the tannic acid modifier. The MS and NMR results of the tannic acid modifier in this example are consistent with those shown in Example 1.

[0050] (5) Add tannic acid modifier (45 mmol) and tannic acid (10 mmol) to a mixed solvent of 150 mL THF and 3 mL water, stir for 20 min, then add magnesium sulfate (45 mmol) and stir at room temperature for 12 h. After concentrating the reaction solution, dilute the concentrate with ethanol, and dialyze through a dialysis bag (molecular weight cutoff 3000D) to remove impurities with molecular weight below 3000D. Concentrate and dry the solution in the dialysis bag to obtain modified tannic acid.

[0051] The IR results of the modified tannic acid in this embodiment are consistent with those shown in Example 1.

[0052] The preparation process of the antioxidant includes the following steps: antioxidant 1076, antioxidant DLTDP, modified tannic acid, nucleating agent HPN-20E and calcium stearate are added to a kneader and stirred for 30 minutes, then heated to 130°C and stirred for another 60 minutes. After the mixing is completed, the mixture is transferred to a storage tank through an insulated pipe, cooled to 35°C and then transported to a granulator for granulation to obtain the antioxidant.

[0053] Example 3

[0054] An antioxidant, by weight, comprises the following components: 60 parts antioxidant 736, 20 parts antioxidant DTPDP, 15 parts modified tannic acid, 15 parts nucleating agent 713, and 20 parts zinc stearate.

[0055] The preparation process of the modified tannic acid includes the following steps:

[0056] (1) Add 0.1 mol of 4-hydroxy-7-N,N-diethylaminocoumarin, 0.12 mol of malononitrile, 0.12 mol of p-nitrobenzaldehyde, and 0.1 mol of potassium hydrogen phthalate (KHP) to 150 mL of deionized water, stir well, and then heat to 50 °C for 7 h. After cooling the reaction solution to room temperature, filter, collect the filter cake (wash the filter cake with deionized water during filtration), dry it, and then slurry it with a mixed solvent (1 g filter cake: 3 mL mixed solvent, V 氯仿 V 乙醇 =1:2) to obtain intermediate 1;

[0057] (2) Take intermediate 1 (0.1 mol) and N,N-dimethylformamide dimethyl acetal (6.5 mol) and react at 115℃ for 20 min; filter the reaction solution and collect the filter cake. During the filtration process, wash the filter cake with ethanol, dry it and recrystallize it with a mixed solvent (dissolve the filter cake with chloroform and then precipitate the solid from the chloroform solution with ethanol) to obtain intermediate 2.

[0058] (3) Take intermediate 2 (0.05 mol) and add it to 100 mL of acetic acid. Then add iron powder (0.9 mol) and react at 28 °C for 12 h. Filter the reaction solution with Celite (wash the filter cake with ethyl acetate during filtration). Collect the filtrate and concentrate it. Dilute the concentrate with water and extract the aqueous phase with ethyl acetate. Wash the ethyl acetate phase with saturated brine. Dry the ethyl acetate phase with sodium sulfate, concentrate it, and pass it through a column (eluent: petroleum ether: ethyl acetate = 10:1) to obtain intermediate 3.

[0059] The MS results of intermediate 3 in this embodiment are consistent with those shown in Example 1.

[0060] (4) Intermediate 3 (0.1 mol), 4-fluoro-3-aldehyde phenylboronic acid (0.1 mol), and magnesium sulfate (4 mmol) were added to 200 mL of dichloromethane and reacted at 30 °C for 8 h. The reaction solution was dried, concentrated, and column chromatography (1 wt% acetic acid was added to the eluent, and the eluent was petroleum ether: ethyl acetate = 7:1) to obtain the tannic acid modifier. The MS and NMR results of the tannic acid modifier in this example are consistent with those shown in Example 1.

[0061] (5) Add tannic acid modifier (41 mmol) and tannic acid (10 mmol) to a mixed solvent of 150 mL THF and 3 mL water, stir for 20 min, then add magnesium sulfate (42 mmol) and stir at room temperature for 16 h. After concentrating the reaction solution, dilute the concentrate with ethanol, and dialyze through a dialysis bag (molecular weight cutoff 3000D) to remove impurities with molecular weight below 3000D. Concentrate and dry the solution in the dialysis bag to obtain modified tannic acid.

[0062] The IR results of the modified tannic acid in this embodiment are consistent with those shown in Example 1.

[0063] The preparation process of the antioxidant includes the following steps: antioxidant 736, antioxidant DTPDP, modified tannic acid, nucleating agent 713 and zinc stearate are added to a kneader and stirred for 30 minutes, then heated to 150°C and stirred for another 45 minutes. After the mixing is completed, the mixture is transferred to a storage tank through an insulated pipe, cooled to 35°C and then transported to a granulator for granulation to obtain the antioxidant.

[0064] Comparative Example 1

[0065] An antioxidant that differs from Example 1 in that it omits modified tannins.

[0066] Comparative Example 2

[0067] An antioxidant, which differs from Example 1 in that the modified tannic acid is replaced with an equal amount of tannic acid.

[0068] Test case

[0069] The antioxidant properties of the antioxidants prepared in Examples 1-3 and Comparative Examples 1-2 were determined. The oxidation induction period of the composite antioxidants was determined by DSC method, and the yellow index of the composite antioxidants was determined according to GB 2409-1980. The results are shown in Table 1.

[0070] Table 1 Antioxidant properties

[0071]

[0072] As shown in Table 1, compared with Comparative Examples 1-2 which omit modified tannic acid, the technical solutions of Examples 1-3 improved the oxidation induction period, indicating that modified tannic acid can optimize the oxidation performance of the polymer. Compared with Comparative Example 3, the technical solutions of Examples 1-3 improved the oxidation induction period and significantly reduced the yellow index, indicating that the modified tannic acid can optimize the yellow index of the polymer.

[0073] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. An antioxidant, characterized in that, By weight, it includes the following components: 30-60 parts primary antioxidant, 8-20 parts secondary antioxidant, 5-15 parts modified tannic acid, 10-15 parts nucleating agent, and 15-20 parts lubricant. The primary antioxidant is a hindered phenolic antioxidant, and the secondary antioxidant is a thioester or phosphite antioxidant. The preparation process of the modified tannic acid includes the following steps: (1) Add 4-hydroxy-7-N,N-diethylaminocoumarin, malononitrile, p-nitrobenzaldehyde and potassium hydrogen phthalate to water, react at 50-70℃ for 5-7h, and then treat to obtain intermediate 1. (2) Intermediate 1 and N,N-dimethylformamide dimethyl acetal were mixed and reacted at 105-115℃ for 20-40 min, and then processed to obtain intermediate 2. (3) Intermediate 2 and iron powder were added to acetic acid and reacted for 12-18 hours. After processing, intermediate 3 was obtained. (4) Add intermediates 3,4-fluoro-3-aldehyde phenylboronic acid and magnesium sulfate to dichloromethane, react for 8-16 hours and then process to obtain tannic acid modifier. (5) Add tannic acid modifier, tannic acid and magnesium sulfate to water and stir for 12-16 hours to obtain the modified tannic acid; The molar ratio of 4-hydroxy-7-N,N-diethylaminocoumarin, malononitrile, p-nitrobenzaldehyde and potassium hydrogen phthalate in step (1) is 1:(1-1.2):(1-1.2):(0.98-1); the molar ratio of intermediate 1 and N,N-dimethylformamide dimethyl acetal in step (2) is 1:(65-75); the molar ratio of intermediate 2 and iron powder in step (3) is 1:(15-18); the molar ratio of intermediate 3, 4-fluoro-3-aldehyde phenylboronic acid and magnesium sulfate in step (4) is 1:(1-1.2):(0.02-0.04); the molar ratio of tannic acid, tannic acid modifier and magnesium sulfate in step (5) is 1:(4.1-4.5):(4.2-4.5).

2. The antioxidant according to claim 1, characterized in that, The hindered phenolic antioxidant is one of antioxidant 1010, antioxidant 1076 and antioxidant 736; the thioester is one of antioxidant DLTDP and antioxidant DTPDP; the phosphite antioxidant is antioxidant 618.

3. The antioxidant according to claim 1, characterized in that, The nucleating agent is one of HPN-20E and nucleating agent 713; the lubricant is selected from one of zinc stearate and calcium stearate.

4. The method for preparing the antioxidant according to any one of claims 1 to 3, characterized in that, The process includes the following steps: adding the main antioxidant, auxiliary antioxidant, modified tannic acid, nucleating agent and lubricant into a kneader and stirring for 30 minutes, then heating to 130-150°C and continuing to stir for 45-60 minutes. After the mixing is completed, the mixture is cooled to 20-45°C and granulated to obtain the antioxidant.

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