Liquid antioxidant, anti-aging modified material and preparation method thereof

Abstract

The invention belongs to the field of materials, and particularly relates to a liquid antioxidant, an anti-aging modified material and a preparation method of the anti-aging modified material. The preparation raw materials of the liquid antioxidant provided by the invention comprise the methyl propionate compound, the catalyst and the micromolecular polyol, compared with the traditional solid antioxidant 1076, the liquid antioxidant can endow a product with more excellent yellowing resistance and heat-resistant stability when being applied to the production of modified materials, and due to the liquid property of the liquid antioxidant, the anti-yellowing property of the product is greatly improved. And the production safety is further improved, and the actual use effect is excellent.

Description

Technical Field

[0001] The present invention belongs to the field of materials, and specifically relates to a liquid antioxidant, an aging-resistant modified material and a preparation method thereof. Background Art

[0002] The raw materials for preparing EVA (ethylene-vinyl acetate copolymer) mainly include ethylene and vinyl acetate. However, the raw materials need to undergo strict purification treatment to ensure the efficient progress of the polymerization reaction and the high stability of the product. Under specific temperature and pressure conditions, ethylene and vinyl acetate will carry out a copolymerization reaction in a reaction kettle. During the copolymerization reaction, a polymerization catalyst is generally added to accelerate the reaction, and at the same time, the temperature and pressure of the reaction kettle need to be precisely controlled to ensure the efficiency of the reaction. By adjusting the feeding ratio of ethylene and vinyl acetate and further granulation processing, EVA particles with different vinyl acetate contents can be produced to meet the requirements of different application fields.

[0003] The EVA particles after granulation can be directly used in various subsequent processing processes, such as injection molding, extrusion, blown film, etc. The EVA particles can be processed into products of various shapes and sizes, such as EVA films, EVA foams, EVA pipes, etc. Because of their excellent physical and chemical properties, they are widely used in the fields of packaging, construction, electronics, automobiles, etc. For example, EVA films have excellent transparency, flexibility and weather resistance, and are widely used in the fields of food packaging, agricultural greenhouses, etc.; EVA foams are widely used in the fields of electronic product packaging, sports shoe soles, etc. because of their good cushioning performance and sound insulation performance. Therefore, the production and application of EVA are of great significance for promoting the development of related industries.

[0004] During the granulation process, in order to maintain the color stability of EVA products and prevent them from undergoing oxidative degradation during storage and transportation, functional antioxidants are usually added. For example, Chinese Patent Application CN105542434A discloses a PU / EVA composite plastic material and a preparation method thereof, and its raw materials for preparation include EVA and antioxidant 1076. However, antioxidant 1076 is a solid powdery substance, and a large amount of dust will be generated during the addition process, which will not only pollute the environment, but also may cause harm to the health of operators. Therefore, in practical applications, appropriate measures need to be taken to reduce the generation of dust, such as using a closed addition system, wearing protective equipment, etc., but it is difficult to achieve complete protection, and it will also cause a certain degree of increase in process costs and operation difficulties.

[0005] Therefore, how to further reduce the danger and cost in the production process on the basis of ensuring the high antioxidant property of EVA products has become an industry-wide technical problem that needs to be solved urgently at present. Summary of the Invention

[0006] To solve the above technical problems, a first aspect of the present invention provides a liquid antioxidant, and the raw materials for its preparation include methyl propionate compounds, catalysts, and small molecule polyols.

[0007] As an implementable case, the mass ratio of the methyl propionate compound to the small molecule polyol is (30 - 40):(50 - 60).

[0008] Further, the structural formula of the methyl propionate compound is:

[0009]

[0010] Further, the small molecule polyol includes 1,2,6 - hexanetriol.

[0011] Further, the catalyst includes an alkali metal amide catalyst.

[0012] Further, the alkali metal amide catalyst includes lithium amide.

[0013] Further, the mass ratio of the methyl propionate compound to the catalyst is 1:(0.01 - 0.1).

[0014] As an implementable case, the preparation method of the liquid antioxidant includes:

[0015] S1. Mix the methyl propionate compound and the small molecule polyol, and raise the temperature to 100 - 110°C under vacuum conditions for 1 - 2 hours of dehydration;

[0016] S2. Then, under normal pressure of 1 atm, add the catalyst;

[0017] S3. Raise the temperature to 155 - 160°C under vacuum conditions and hold for 3 - 5 hours of reaction;

[0018] S4. Raise the temperature to 170 - 175°C under vacuum conditions and hold for 5 - 8 hours of reaction. After the reaction is completed, take a sample for analysis. When the content of the acrylate methyl compound is less than 1 wt%, filter, collect the liquid product, and purify to obtain the liquid antioxidant.

[0019] A second aspect of the present invention provides an anti - aging modified material, and the raw materials for its preparation include a substrate and the liquid antioxidant.

[0020] As an implementable case, the mass ratio of the substrate to the liquid antioxidant is 100:(0.1 - 1).

[0021] As an implementable case, the substrate includes one of PP, PE, PVC, EVA, PET, PA, and PBT.

[0022] Further, the substrate is EVA.

[0023] The third aspect of the present invention provides a method for preparing an anti-aging modified material, including:

[0024] Adding the substrate into a twin-screw extruder, then using a liquid metering pump to pump a liquid antioxidant into the twin-screw extruder, and performing hot melt extrusion granulation to obtain the anti-aging modified material.

[0025] In the production of traditional EVA materials, in order to ensure more excellent anti-aging performance and transportation and storage stability of EVA products, antioxidants are added during the preparation process. Generally, they are phosphite oxidants, including antioxidant 1076. Antioxidant 1076 mainly inhibits oxidation reactions by capturing free radicals. When EVA products are affected by external factors such as oxygen and light, free radicals will be generated. Free radicals will trigger the generation of more free radicals through a chain reaction, thus accelerating the progress of the oxidation reaction. The chemical structure of antioxidant 1076 contains p-cresol and a propane skeleton, with two alkyl substituents, so it can react quickly with free radicals and prevent free radicals from further initiating an oxidation chain reaction, thereby inhibiting the progress of the oxidation reaction.

[0026] However, a certain amount of dust will escape during the feeding process of solid powder antioxidant 1076, polluting the environment of the production workshop, affecting the health of production personnel, and more seriously, it may even cause serious safety accidents such as dust explosions. Therefore, in the modified preparation process of EVA in the present invention, a liquid antioxidant is creatively used, especially the liquid product of methyl propionate compound and small molecule polyol catalyzed by lithium amide, which can effectively avoid the safety problems brought by solid powder antioxidants and improve the utilization rate of antioxidant raw materials.

[0027] In addition, compared with the traditional antioxidant 1076, the liquid antioxidant provided by the present invention, when applied in EVA production, can endow the product with more excellent yellowing resistance and heat stability. The inventor speculates that this is mainly because the liquid antioxidant molecule provided by the present invention contains phenolic hydroxyl groups and alcoholic hydroxyl groups, which can act as hydrogen donors and react with unstable free radicals generated during the thermal oxidation process of high molecular materials. By removing a hydrogen atom, the original free radicals can be scavenged, and the liquid antioxidant itself is transformed into a relatively stable free radical form, which is not easy to initiate a new free radical chain reaction, thereby terminating the chain reaction and achieving the technical effects of high-efficiency antioxidant and high-temperature yellowing resistance.

[0028] Beneficial effects

[0029] (1) The liquid antioxidant provided by the present invention can be continuously added through a liquid metering pump, avoiding the dust pollution caused by the powder characteristics of the traditional solid antioxidant 1076, significantly reducing the risk of dust flash explosion at the production site, simplifying the operation process, and improving the addition accuracy and efficiency.

[0030] (2) The liquid antioxidant provided by the present invention is applied in the modification process of EVA. The average OIT (oxidation induction time) of the prepared product is 15.62 minutes, which is significantly better than 13.28 minutes of antioxidant 1076, indicating that it can more effectively delay the oxidation of EVA materials and extend the storage stability and service life of the product.

[0031] (3) The liquid antioxidant provided by the present invention is applied in the modification process of EVA. After the prepared product is aged in an 80 °C oven for 168 hours, the YI (yellowing index) of the product is only 1.1, which is much lower than 2.1 of antioxidant 1076. Therefore, the liquid antioxidant provided by the present invention has better long-term color stability and long-term anti-yellowing performance, and is suitable for application scenarios with high requirements for color stability.

[0032] (4) The liquid antioxidant prepared by the present invention can be accurately metered through a closed pipeline, avoiding the problems of carbon deposition and black spots caused by the adhesion of the traditional powder antioxidant to the reactor wall, reducing the quality loss of raw materials, improving the utilization rate of raw materials, and ensuring the uniform and stable performance of EVA products.

[0033] (5) In the present invention, due to the use of the liquid antioxidant, dust pollution can be effectively eliminated, the production site environment is cleaner, the risk of workers inhaling harmful dust is reduced, meeting the occupational health and safety standards, and at the same time reducing the equipment cleaning and maintenance costs; at the same time, experiments prove that the liquid antioxidant provided by the present invention also has more excellent antioxidant and aging resistance performance in the preparation of EVA compared with the same type of liquid antioxidants on the market, including antioxidant 1135 and antioxidant 1315. Description of the Drawings

[0034] Figure 1 Schematic diagram of the high-temperature aging performance test of the modified material prepared in Example 1.

[0035] Figure 2 Schematic diagram of the high-temperature aging performance test of the modified material prepared in Comparative Example 1. Detailed Description of the Invention

[0036] Example 1

[0037] In the first aspect of this example, a liquid antioxidant is provided. The preparation raw materials are as follows by mass fraction: specifically, 35 parts of methyl propionate compound, 55 parts of 1,2,6-hexanetriol, and 1 part of lithium amide.

[0038] The structural formula of the methyl propionate compound is as follows:

[0039]

[0040] The specific preparation method of the liquid antioxidant is as follows:

[0041] S1. Mix the methyl propionate compound and 1,2,6-hexanetriol, add them into a four-necked flask equipped with a thermometer and a condensation device, and heat up to 105 °C under a vacuum condition of -0.1 MPa to dehydrate for 1 h;

[0042] S2. Then, under normal pressure of 1 atm, add lithium amide;

[0043] S3. Heat up to 160 °C under a vacuum condition of -0.1 MPa and keep the temperature for reaction for 3 h;

[0044] S4. Heat up to 175 °C under a vacuum condition of -0.1 MPa and keep the temperature for reaction for 7 h. After the reaction is completed, take a sample for analysis. The content of the acrylate compound is measured to be less than 1 wt%. Filter, collect the liquid product, and purify it to obtain the liquid antioxidant.

[0045] In the second aspect of this example, a weather-resistant modified material is provided. The preparation raw materials are as follows by mass fraction: 100 parts of EVA and 0.5 part of the liquid antioxidant.

[0046] The EVA is purchased from Jiangsu Sierbang Petrochemical Co., Ltd. and the model is V5120J.

[0047] In the third aspect of this example, a preparation method of a weather-resistant modified material is provided, which is specifically as follows:

[0048] Add EVA into a twin-screw extruder, and then use a liquid metering pump to pump the liquid antioxidant into the twin-screw extruder, and carry out hot melt extrusion granulation at 190 °C to obtain the weather-resistant modified material.

[0049] Comparative Example 1

[0050] In the first aspect of this example, a weather-resistant modified material is provided. The preparation raw materials are as follows by mass fraction: 100 parts of EVA and 0.5 part of a solid antioxidant.

[0051] The EVA is purchased from Jiangsu Sierbang Petrochemical Co., Ltd. and the model is V5120J.

[0052] The solid antioxidant is antioxidant 1076 (CAS: 2082-79-3.), and it is purchased from BASF SE.

[0053] In the second aspect of this example, a preparation method of a weather-resistant modified material is provided, which is specifically as follows:

[0054] Add EVA and antioxidant 1076 into a twin-screw extruder, and melt-extrude and pelletize at 190 °C to obtain the aging-resistant EVA modified material.

[0055] Comparative Example 2

[0056] In the first aspect of this example, an aging-resistant modified material is provided. The specific preparation raw materials are as follows according to mass parts: 100 parts of EVA and 0.5 part of liquid antioxidant.

[0057] The EVA is purchased from Jiangsu Sierbang Petrochemical Co., Ltd., and the model is V5120J.

[0058] The liquid antioxidant is antioxidant 1135 (CAS: 125643-61-0), and it is purchased from BASF SE.

[0059] In the second aspect of this example, a preparation method of an aging-resistant modified material is provided, specifically as follows:

[0060] Add EVA into a twin-screw extruder, then use a liquid metering pump to pump antioxidant 1135 into the twin-screw extruder, and melt-extrude and pelletize at 190 °C to obtain the aging-resistant EVA modified material.

[0061] Comparative Example 3

[0062] In the first aspect of this example, an aging-resistant modified material is provided. The specific preparation raw materials are as follows according to mass parts: 100 parts of EVA and 0.5 part of liquid antioxidant.

[0063] The EVA is purchased from Jiangsu Sierbang Petrochemical Co., Ltd., and the model is V5120J.

[0064] The liquid antioxidant is antioxidant 1315 (CAS: 171090-93-0), and it is purchased from BASF SE.

[0065] In the second aspect of this example, a preparation method of an aging-resistant modified material is provided, specifically as follows:

[0066] Add EVA into a twin-screw extruder, then use a liquid metering pump to pump antioxidant 1315 into the twin-screw extruder, and melt-extrude and pelletize at 190 °C to obtain the aging-resistant EVA modified material.

[0067] Performance Test

[0068] I. Oxidation Induction Time (OIT) Test

[0069] Test objects: The modified materials prepared in the examples and Comparative Examples 1-3.

[0070] Test method: Turn on the DSC device, perform calibration to ensure the accuracy of temperature and heat flow measurements, connect nitrogen and oxygen, and check the gas flow rate and purity to ensure no impurity interference; place the prepared modified material sample into the DSC sample pan, heat the sample to the predetermined temperature of 200 °C in a nitrogen atmosphere, and when the sample reaches the predetermined temperature, switch to an oxygen atmosphere, maintain a constant temperature, record the oxygen flow rate and the switching time; observe the change of the heat flow signal through the DSC curve, determine the time point when the oxidation reaction starts, that is, the time when the heat flow signal significantly rises, record this time as the oxidation induction time, test each sample twice, calculate the average OIT value, and the test results are shown in Table 1 for details.

[0071] Table 1

[0072] First OIT value (min) Second OIT value (min) Average OIT value (min) Example 1 15.75 15.48 15.62 Comparative Example 1 13.05 13.51 13.28 Comparative Example 2 8.64 9.11 8.75 Comparative Example 3 10.18 10.09 10.42

[0073] From the experimental results in Table 1, it can be seen that when the liquid antioxidant provided by the present invention is applied to EVA modification, the OIT value is longer than that of Comparative Examples 1 - 3, indicating that the liquid antioxidant provided by the present invention can extend the storage performance of the product and the physical stability performance of the product itself.

[0074] II. Yellowing Index Test

[0075] Test object: The modified materials prepared in the examples and Comparative Examples 1 - 3.

[0076] Test method: Refer to the ASTM E313 method to test the yellowing index of the modified material at room temperature of 25 °C, and the experimental results are shown in Table 2 for details.

[0077] Table 2

[0078] Serial number Yellowing index Example 1 0.51 Comparative Example 1 0.52 Comparative Example 2 3.5 Comparative Example 3 2.1

[0079] The experimental results show that the yellowing resistance performance of the liquid antioxidant provided by the present invention is improved to a certain extent after application compared with that of antioxidant 1076.

[0080] III. High - temperature Aging Performance Test

[0081] Test object: The modified materials prepared in the examples and Comparative Examples 1 - 3.

[0082] Test method: Place the EVA modified material in an oven at 80 °C for aging for 168 h, then observe the color of the modified material and test the yellowing index, and the schematic diagram of the experimental results is shown in Figure 1-2 and Table 3.

[0083] Table 3

[0084] Serial number Yellowing index Example 1 1.1 Comparative Example 1 2.1 Comparative Example 2 8.2 Comparative Example 3 6.7

[0085] The experimental results show that, from the color comparison of the products, it can be seen that after the application of the liquid antioxidant provided by the present invention, the high-temperature aging resistance protection performance of the products is significantly better than that of antioxidant 1076, and the actual application effect is more excellent.

Claims

1. A liquid antioxidant, characterized in that: The preparation raw materials include methyl propionate compound, catalyst and small molecule polyol.

2. The liquid antioxidant according to claim 1, characterized in that The mass ratio of the methyl propionate compound to the small molecule polyol is (30-40):(50-60).

3. The liquid antioxidant according to claim 2, characterized in that The structural formula of the methyl propionate compound is:

4. The liquid antioxidant according to claim 2, characterized in that The small molecule polyol includes 1,2,6-hexanetriol.

5. The liquid antioxidant according to claim 1, characterized in that The catalyst includes an alkali metal amine-based catalyst.

6. The liquid antioxidant according to claim 5, characterized in that The alkali metal amine-based catalyst includes lithium amide.

7. An aging-resistant modified material, characterized in that: The preparation raw materials include a base material and the liquid antioxidant according to any one of claims 1-6.

8. The aging-resistant modified material according to claim 7, characterized in that: The mass ratio of the base material to the liquid antioxidant is 100:(0.1-1).

9. The aging-resistant modified material according to claim 8, characterized in that: The substrate includes one of PP, PE, PVC, EVA, PET, PA, and PBT.

10. A method for preparing an aging-resistant modified material according to any one of claims 7 to 9, characterized in that: include: The substrate is added into a twin-screw extruder, and then a liquid metering pump is used to pump a liquid antioxidant into the twin-screw extruder, and hot-melt extrusion granulation is performed to obtain an aging-resistant modified material.

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