Efficient compound antioxidant for polyolefin as well as preparation method and application of efficient compound antioxidant

Abstract

The invention relates to the field of antioxidants, and particularly discloses an efficient compound antioxidant for polyolefin as well as a preparation method and application of the efficient compound antioxidant. The high-efficiency compound antioxidant for polyolefin is prepared from the following raw materials: a main antioxidant, an auxiliary antioxidant and polyol in a weight ratio of 15: (0.8-1.2): (2-5), the auxiliary antioxidant comprises vitamin E and an o-vanillin derivative, and the polyol comprises one or more of trimethylolpropane, trimethylolethane, neopentyl glycol, pentaerythritol and dipentaerythritol. The product disclosed by the invention can be mixed into polyolefin and has a good antioxidant effect, the dosage of the efficient compound antioxidant is 0.18-0.19 wt% of the total amount of the polyolefin, so that the polyolefin has excellent processing stability and color stability, and the efficient compound antioxidant disclosed by the invention can control the yellowness index of the polyolefin subjected to five-time processing to be 1.83 or below, so that the polyolefin has a good anti-oxidation effect. And the change rate of the melt index before and after processing is controlled within 31%.

Description

Technical Field

[0001] The present application relates to the technical field of antioxidants, and in particular to a high-efficiency compounded antioxidant for polyolefins, and a preparation method and application thereof. Background Art

[0002] During processing and use, polymers are susceptible to external factors such as light, heat, and oxygen, leading to aging phenomena such as hardening, stickiness, powdering, cracking, and discoloration, significantly shortening their service life. Extending the service life of polymers while maintaining their excellent properties can directly reduce environmental pollution and resource waste. To extend the service life of polymer materials and enhance their performance during processing and use, antioxidants are often added to polymers without changing the production process to inhibit or delay oxidation reactions, thereby improving the material's processing stability and long-term thermal stability. Hindered phenolic primary antioxidants serve as both processing stabilizers and long-term thermal stabilizers. Phosphite-based secondary antioxidants, on the other hand, act during polymer processing and are typically used in combination with primary antioxidants. Most phenolic antioxidants cause varying degrees of discoloration, limiting their use in applications where product color is critical. A common approach is to add phosphite-based secondary antioxidants to inhibit phenolic discoloration and improve processing stability.

[0003] Currently, some researchers have used a method of combining phenolic antioxidants with phosphites to inhibit phenolic color change, but the effect is limited. In particular, for phenolic antioxidants with severe color change, such as butylated hydroxytoluene (BHT), vitamin E, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene (Antioxidant 1330), and 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanuric acid (Antioxidant 3114), even with the addition of phosphites, it is still difficult to inhibit the color change of the system. Therefore, how to further reduce the color change while ensuring the stability of material processing remains a technical problem that needs to be solved urgently. Summary of the Invention

[0004] In order to solve the above technical problems, the present application provides a high-efficiency compound antioxidant for polyolefins, and a preparation method and application thereof.

[0005] In the first aspect, the present application provides a high-efficiency compound antioxidant for polyolefins, the raw materials used including a primary antioxidant, a secondary antioxidant and a polyol in a weight ratio of 15:(0.8-1.2):(2-5), wherein the polyol includes one or more of trimethylolpropane, trimethylolethane, neopentyl glycol, pentaerythritol and dipentaerythritol.

[0006] By adopting the above technical solution, the present application compounds the primary antioxidant, the secondary antioxidant and the polyol according to a specific ratio, which can significantly improve the processing stability of the polyolefin material, while effectively suppressing the color change problem caused by the phenolic antioxidant. Specifically, the primary antioxidant provides basic antioxidant properties, and the vitamin E and o-vanillin derivatives in the secondary antioxidant contribute greatly to improving the material processing stability. The primary antioxidant and the secondary antioxidant compound can play a good synergistic role and greatly improve the processing stability of the polyolefin material; but after introducing vitamin E and o-vanillin derivatives, the yellowness index of the material becomes large, and the color change and color pollution of the material are serious at this time. Therefore, the present application adds a polyol composed of one or more of trimethylolpropane, trimethylolethane, neopentyl glycol, pentaerythritol and dipentaerythritol, which can significantly improve color stability. The compounding system under the synergistic effect of the three enables the polyolefin material to still maintain a low melt index change and yellowness index during multiple processing, thereby achieving excellent processing stability and color stability.

[0007] Optionally, the main antioxidant is antioxidant B215.

[0008] By adopting the above technical solution, the main antioxidant in this application is antioxidant B215, which is compounded by tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester (antioxidant 1010) and tris[2,4-di-tert-butylphenyl] phosphite (antioxidant 168) in a weight ratio of 1:2. It can provide stable antioxidant performance and synergize with vitamin E, o-vanillin derivatives and polyols to further improve the processing stability and color stability of the material. As a basic antioxidant, antioxidant B215 can significantly reduce the melt index change of the material during multiple processing processes after compounding with vitamin E and o-vanillin derivatives, thereby improving processing stability; after compounding with polyols, it can effectively inhibit the color change caused by phenolic antioxidants and improve the color stability of the material.

[0009] Preferably, the weight ratio of vitamin E to the o-vanillin derivative is 2:(1-2).

[0010] By adopting the above technical solution, the present application strictly controls the weight ratio of vitamin E and o-vanillin derivative, further optimizing the antioxidant effect of the secondary antioxidant and its synergistic effect with the primary antioxidant.

[0011] Preferably, the o-vanillin derivative is prepared by the following method: o-vanillin and 2,6-diaminopurine are mixed in a weight ratio of 15:(2-3), reacted, filtered to obtain a solid, immersed in DMF and allowed to stand, filtered to obtain a solid, and dried to obtain an o-vanillin derivative.

[0012] By adopting the above-mentioned technical solution, the present application obtains an o-vanillin derivative by co-reaction of o-vanillin and 2,6-diaminopurine, which can not only significantly improve the antioxidant capacity of polyolefin materials, but also has good thermal stability and processing stability. When used together with other substances, the melt index change rate of the polyolefin material after five processings can be controlled within 31%.

[0013] Preferably, the weight ratio of the primary antioxidant to the secondary antioxidant is 15:1.

[0014] By adopting the above technical solution, the present application compounds the primary and secondary antioxidants in a weight ratio of 15:1, further improving the processing stability of the polyolefin material while maintaining the material's excellent properties. Furthermore, compared to other ratios, this ratio can better leverage the synergistic effects of vitamin E and o-vanillin derivatives, reducing the degree of color change and thus improving the material's color stability.

[0015] Preferably, the weight ratio of the primary antioxidant to the polyol is 15:2.5.

[0016] By adopting the above technical solution, a weight ratio of primary antioxidant to polyol of 15:2.5 can further optimize the performance of the compounded antioxidant. Specific benefits include significantly reducing the discoloration caused by phenolic antioxidants while ensuring processing stability, thereby improving the material's color stability. Furthermore, this ratio exhibits excellent synergistic effects between the polyol, primary antioxidant, and secondary antioxidant, enabling the compounded antioxidant to maintain low melt index fluctuations and yellowness index during multiple processing steps, thereby achieving both enhanced processing stability and color stability.

[0017] Preferably, the polyol comprises neopentyl glycol, trimethylolethane and pentaerythritol in a weight ratio of 20:(2-3):(2-3).

[0018] By adopting the above technical solution, the present application prefers trimethylolethane, neopentyl glycol, and pentaerythritol in a weight ratio of 20:(2-3):(2-3) as the polyol component, further improving the color stability of the antioxidant system while reducing the color change problem caused by phenolic antioxidants. This selection not only optimizes the overall performance of the formula, but also achieves excellent levels of processing stability and color stability, thus meeting the needs of application scenarios with strict requirements on polymer material performance.

[0019] In a second aspect, the present application provides a method for preparing a high-efficiency compound antioxidant for polyolefins, comprising the following steps: blending a primary antioxidant, a secondary antioxidant, and a polyol to obtain a high-efficiency compound antioxidant.

[0020] By adopting the above technical solution, the synergistic compounding of the main antioxidant, the secondary antioxidant and the polyol is achieved, which significantly improves the processing stability and color stability of the polyolefin material.

[0021] In a third aspect, the present application provides an application of a high-efficiency compounded antioxidant for polyolefins, comprising the following steps: blending the above-mentioned high-efficiency compounded antioxidant, an acid scavenger and polyolefins, wherein the amount of the high-efficiency compounded antioxidant is 0.18-0.19 wt% of the total amount of polyolefins.

[0022] By adopting the above technical solution, the present application can significantly improve the processing stability of polyolefin materials after blending the high-efficiency compound antioxidant with the acid absorber and polyolefin, while effectively suppressing the color change problem caused by phenolic antioxidants, thereby greatly improving the color stability of the material. Specifically, the synergistic effect of the main antioxidant, secondary antioxidant and polyol in the high-efficiency compound antioxidant makes the melt index of polyolefin change less during multiple processing, indicating that its processing performance is more stable; and the introduction of polyol further reduces the yellowness index and improves the color performance of the material. In addition, by controlling the dosage of the high-efficiency compound antioxidant within the range of 0.18-0.19wt%, while ensuring its excellent performance, it also optimizes the cost and use effect. Experimental data show that the high-efficiency compound antioxidant of the present application can control the yellowness index of the polyolefin primary molding to below -1.19, the yellowness index of the five processings to below 1.83, and the melt index change rate of the five processings to within 31%.

[0023] The polyolefin in this application is described by taking polyethylene as an example. Those skilled in the art may replace different polyolefins according to actual conditions, and this does not limit the scope of protection of this application.

[0024] Preferably, the amount of the high-efficiency compounded antioxidant is 0.185 wt% of the total amount of polyolefin.

[0025] By employing the above-mentioned technical solution, the present application precisely controls the addition amount of a high-efficiency compounded antioxidant to polyolefins, achieving optimal processing stability and color stability. Specifically, setting the dosage of the high-efficiency compounded antioxidant to 0.185 wt% of the total polyolefin ensures a good synergistic effect between the antioxidant and the polyolefin matrix, further suppressing degradation and color change during processing.

[0026] Preferably, the acid scavenger is calcium stearate.

[0027] In summary, this application has the following beneficial technical effects: 1. This application introduces a polyol on the basis of a primary antioxidant and a secondary antioxidant, effectively suppressing the color change problem caused by phenolic antioxidants and significantly improving the color stability of the material. In particular, after multiple processing, the yellowness index is significantly reduced. The synergistic effect between the primary antioxidant, the secondary antioxidant, and the polyol greatly improves the processing stability of the polyolefin material, which is manifested in a significantly reduced fluctuation range of the melt index, thereby extending the service life of the material. 2. This application optimizes formulation costs while ensuring excellent processing stability and color stability. By reducing the amount of polyol used, it still maintains good performance, providing an economically feasible solution for practical applications. 3. After the high-efficiency compound antioxidant of the present application is blended with the acid absorber and polyolefin, it can significantly improve the processing stability of the polyolefin material, while effectively inhibiting the color change problem caused by the secondary antioxidant, thereby greatly improving the color stability of the material. Experimental data show that the high-efficiency compound antioxidant of the present application can control the yellowness index of the primary polyolefin molding to below -1.19, the yellowness index of the five-processing to below 1.83, and the melt index change rate of the five-processing to within 31%. DETAILED DESCRIPTION

[0028] Material Source Unless otherwise specified, the raw materials used in this application are all commercially available products, specifically: o-Vanillin was purchased from Aladdin (Shanghai) Biochemical Technology Co., Ltd. with a purity of 99 wt%; 2,6-Diaminopurine was purchased from Anaiji Chemical Reagent Co., Ltd. with a purity of 98 wt%; Antioxidant 1010 (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) was purchased from BASF under the brand name Irganox 1010; Antioxidant 168 (tris[2,4-di-tert-butylphenyl]phosphite), purchased from BASF, brand name Irgafos 168; Vitamin E, purchased from BASF, brand Irganox E201; Trimethylolpropane, trimethylolethane, neopentyl glycol, pentaerythritol, and dipentaerythritol were purchased from Sinopharm Chemical Reagent Co., Ltd.; Calcium stearate, purchased from BASF; Polyethylene powder was purchased from Sinopec Maoming Petrochemical Co., Ltd. with the specification of DFDA-7042.

[0029] The present application is further described in detail below with reference to preparation examples, embodiments and comparative examples.

[0030] Preparation Example 1 The preparation method of o-vanillin derivatives comprises the following steps: 15 g of o-vanillin was dispersed in 150 mL of ethanol, and then 3 g of 2,6-diaminopurine was weighed and dispersed in 100 mL of ethanol. The prepared o-vanillin ethanol solution was added dropwise to the 2,6-diaminopurine ethanol solution, and stirred and refluxed at 70°C for 6 hours. The solvent was then removed by filtration, and the mixture was washed with ethanol and dried to obtain a solid substance. The solid substance was immersed in DMF, allowed to stand overnight, and then the solid substance was taken out and vacuum dried at 60°C for 4 hours to obtain an o-vanillin derivative.

[0031] Preparation Example 2 The preparation method of o-vanillin derivatives comprises the following steps: 15 g of o-vanillin was dispersed in 150 mL of ethanol, and 2 g of 2,6-diaminopurine was weighed and dispersed in 100 mL of ethanol. The prepared o-vanillin ethanol solution was added dropwise to the 2,6-diaminopurine ethanol solution, and stirred and refluxed at 70°C for 6 hours. The solvent was then removed by filtration, and the mixture was washed with ethanol and dried to obtain a solid substance. The solid substance was immersed in DMF, allowed to stand overnight, and then the solid substance was taken out and vacuum dried at 60°C for 4 hours to obtain an o-vanillin derivative.

[0032] Example 1 A method for preparing a high-efficiency compound antioxidant for polyolefins comprises the following steps: 150 g of primary antioxidant (50 g of antioxidant 1010 and 100 g of antioxidant 168), 8 g of secondary antioxidant (4 g of vitamin E and 4 g of the o-vanillin derivative obtained in Preparation Example 1) and 50 g of polyol were blended to obtain a high-efficiency compound antioxidant. The specific substances of the polyol are shown in Table 1.

[0033] Example 2 A method for preparing a high-efficiency compound antioxidant for polyolefins comprises the following steps: 150 g of primary antioxidant (50 g of antioxidant 1010 and 100 g of antioxidant 168), 12 g of secondary antioxidant (8 g of vitamin E and 4 g of the o-vanillin derivative obtained in Preparation Example 2) and 20 g of polyol were blended to obtain a high-efficiency compound antioxidant. The specific substances of the polyol are shown in Table 1.

[0034] Examples 3-10 A method for preparing a high-efficiency compound antioxidant for polyolefins comprises the following steps: 150 g of primary antioxidant (50 g of antioxidant 1010 and 100 g of antioxidant 168), 10 g of secondary antioxidant (5 g of vitamin E and 5 g of the o-vanillin derivative obtained in Preparation Example 1) and 25 g of polyol were blended to obtain a high-efficiency compound antioxidant. The specific substances of the polyol are shown in Table 1.

[0035] Table 1 Polyol formulations of Examples 1-10 Examples 11-14 A method for preparing a high-efficiency compounded antioxidant for polyolefins, which differs from Example 8 in that the ratio of the polyols in Table 2 is used, and the rest is the same as Example 8.

[0036] Table 2 Polyol formulations of Examples 11-14 Example 11 12 13 14 Trimethylolethane 3g 2g 2.5g 1.5g Neopentyl glycol 20g 20g 10g 22g Pentaerythritol 2g 3g 2.5g 1.5g Comparative Example 1.1 The difference from Example 1 is that vitamin E is removed, the amount of the o-vanillin derivative prepared in Preparation Example 1 is 8 g, and the rest is the same as Example 1.

[0037] Comparative Example 1.2 The difference from Example 1 is that the o-vanillin derivative prepared in Preparation Example 1 is removed, the amount of vitamin E used is 8 g, and the rest is the same as Example 1.

[0038] Comparative Example 2 The difference from Example 1 is that the polyol is removed, and the rest is the same as Example 1.

[0039] Comparative Example 3 The difference from Example 1 is that the amount of the secondary antioxidant is 5 g (2.5 g of vitamin E and 2.5 g of the o-vanillin derivative obtained in Preparation Example 1), and the rest is the same as Example 1.

[0040] Comparative Example 4 The difference from Example 1 is that the amount of the secondary antioxidant is 15 g (7.5 g of vitamin E and 7.5 g of the o-vanillin derivative obtained in Preparation Example 1), and the rest is the same as Example 1.

[0041] Comparative Example 5 The difference from Example 1 is that the amount of polyol used is 15 g, and the rest is the same as Example 1.

[0042] Comparative Example 6 The difference from Example 1 is that the amount of polyol used is 60 g, and the rest is the same as Example 1.

[0043] Comparative Example 7 The difference from Example 1 is that all the o-vanillin derivatives prepared in Preparation Example 1 are replaced by o-vanillin, and the rest are the same as Example 1.

[0044] Performance testing The products obtained in the examples and comparative examples were mixed with polyethylene powder in a high-speed mixer at a speed of 1800 r / min for 2 min to obtain a uniformly mixed blended powder. The above blend was processed by a twin-screw extruder to obtain initial blended pellets, which were recorded as 0X; the twin-screw temperature from the barrel to the die was set to 80°C-205°C-210°C-215°C-220°C-225°C-230°C, the screw speed was 150 rpm, and the pelletizer speed was 40 rpm; the pellets obtained above were subjected to multiple extrusion processes using a single-screw extruder, and the pellets after the fifth process were collected and recorded as 5X. The single-screw temperature from the barrel to the die was set to 250°C-255°C-260°C, the screw speed was 70 rpm, and the pelletizer speed was 50 rpm.

[0045] The melt index (MFI) and yellowness index (YI) of 0X and 5X were tested with reference to ISO 1133:2005 and ASTM 313, respectively. The melt index test conditions were a temperature of 230° C. and a load of 2.16 kg.

[0046] Table 3 Test results Data Analysis: As can be seen from Table 1, the high-efficiency compounded antioxidants of Examples 1-10 can control the yellowness index of the primary polyolefin molding to -1.53 to -1.19, the yellowness index of the five processings to 0.50-1.83, and the melt index change rate of the five processings to 22.36-30.33%. This proves that in the high-efficiency compounded antioxidant of the present application, the compounded system formed by the synergistic effect of the primary antioxidant, the secondary antioxidant and the polyol can enable the polyolefin material to maintain a low melt index change and yellowness index during multiple processing, thereby achieving excellent processing stability and color stability.

[0047] The difference between Examples 11-14 and Example 8 is that the weight ratio of trimethylolethane, neopentyl glycol, and pentaerythritol is changed in this application. The results show that the melt index change rate of Examples 11-13 is lower than that of Examples 8 and 14, and also has a lower initial molding yellowness index and five-processing yellowness index. This proves that by optimizing the weight ratio of trimethylolethane, neopentyl glycol, and pentaerythritol, this application further improves the color stability of the antioxidant system and reduces the color change problem caused by phenolic antioxidants. This choice not only optimizes the overall performance of the formula, but also achieves excellent levels of processing stability and color stability, thereby meeting the requirements of use scenarios with strict requirements on the performance of polymer materials.

[0048] Comparative Examples 1.1-1.2 removed vitamin E and o-vanillin derivatives respectively compared to Example 1. The results showed that the melt index change rate of the five processes increased significantly, proving that vitamin E and o-vanillin derivatives in the secondary antioxidants can further enhance processing stability.

[0049] Compared with Example 1, the polyol was removed from Comparative Example 2. The results showed that the yellowness index of the initial molding and the yellowness index of the five-processing were significantly improved, proving that the polyol can significantly improve the color stability.

[0050] The difference between Comparative Examples 3-6 and Example 1 is that the dosage of each substance is different. The results show that the comprehensive data are worse than that of Example 1, which proves that the present application can significantly improve the processing stability of polyolefin materials by compounding the main antioxidant, secondary antioxidant and polyol in a specific proportion, while effectively suppressing the color change problem caused by phenolic antioxidants.

[0051] Compared with Example 1, Comparative Example 7 replaced all the o-vanillin derivatives with o-vanillin. The results showed that the comprehensive data were worse than those in Example 1, proving that the o-vanillin derivatives of the present application can not only significantly improve the antioxidant capacity of polyolefin materials, but also have good thermal stability and processing stability.

[0052] The embodiments of this specific implementation method are all preferred embodiments of the present application and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A high-efficiency compound antioxidant for polyolefins, characterized in that: The raw materials used include a primary antioxidant, a secondary antioxidant and a polyol in a weight ratio of 15:(0.8-1.2):(2-5), wherein the secondary antioxidant includes vitamin E and an o-vanillin derivative, and the polyol includes one or more of trimethylolpropane, trimethylolethane, neopentyl glycol, pentaerythritol and dipentaerythritol.

2. A high-efficiency compounded antioxidant for polyolefins according to claim 1, characterized in that: The weight ratio of the vitamin E to the o-vanillin derivative is 2:(1-2).

3. A high-efficiency compounded antioxidant for polyolefins according to claim 1, characterized in that: The o-vanillin derivative is prepared by the following method: o-vanillin and 2,6-diaminopurine are mixed in a weight ratio of 15:(2-3), reacted, filtered to obtain a solid, immersed the solid in DMF and allowed to stand, filtered to obtain a solid, and dried to obtain the o-vanillin derivative.

4. A high-efficiency compounded antioxidant for polyolefins according to claim 1, characterized in that: The weight ratio of the primary antioxidant to the secondary antioxidant is 15:

1.

5. A high-efficiency compounded antioxidant for polyolefins according to claim 1, characterized in that: The weight ratio of the primary antioxidant to the polyol is 15:2.

5.

6. A high-efficiency compounded antioxidant for polyolefins according to claim 1, characterized in that: The polyol includes neopentyl glycol, trimethylolethane and pentaerythritol in a weight ratio of 20:(2-3):(2-3).

7. A method for preparing a high-efficiency compounded antioxidant for polyolefins according to any one of claims 1 to 6, characterized in that: The following steps are involved: The primary antioxidant, the secondary antioxidant and the polyol are blended to obtain a high-efficiency compound antioxidant.

8. An application of a high-efficiency compound antioxidant for polyolefins, characterized in that: The following steps are involved: The high-efficiency compound antioxidant and the acid scavenger according to any one of claims 1 to 6 are blended with polyolefin, wherein the amount of the high-efficiency compound antioxidant is 0.18-0.19 wt% of the total amount of the polyolefin.

9. The use of a high-efficiency compounded antioxidant for polyolefins according to claim 8, characterized in that: The amount of the high-efficiency compound antioxidant is 0.185 wt % of the total amount of polyolefin.

10. The use of a high-efficiency compounded antioxidant for polyolefins according to claim 8, characterized in that: The acid scavenger is calcium stearate.

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