Liquid antioxidant, aging-resistant modified material and preparation method therefor

Abstract

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 therefor. Starting materials for preparing the liquid antioxidant provided by the present invention comprise a methyl propionate compound, a catalyst and a small molecule polyol. Compared with a traditional solid antioxidant 1076, the liquid antioxidant, when applied to the production of modified materials, can endow products with more excellent yellowing resistance and heat resistance stability; and because of the liquid property, the production safety is further improved, and the actual use effect is excellent.

Description

A liquid antioxidant, an aging-resistant modified material and its preparation method Technical Field

[0001] This invention belongs to the field of materials, specifically relating to a liquid antioxidant, an aging-resistant modified material, and its preparation method. Background Technology

[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 to ensure efficient polymerization and high product stability. Under specific temperature and pressure conditions, ethylene and vinyl acetate undergo a copolymerization reaction in a reactor. During the copolymerization process, a polymerization catalyst is generally added to accelerate the reaction, and the temperature and pressure of the reactor need to be precisely controlled to ensure high efficiency. By adjusting the feed ratio of ethylene and vinyl acetate and further granulating, EVA particles with different vinyl acetate contents can be produced to meet the needs of different application fields.

[0003] Granulated EVA granules can be directly used in various subsequent processing steps, such as injection molding, extrusion, and blown film production. EVA granules can be processed into products of various shapes and sizes, such as EVA films, EVA foams, and EVA tubes. Due to their excellent physical and chemical properties, they are widely used in packaging, construction, electronics, and automotive industries. For example, EVA films, with their excellent transparency, flexibility, and weather resistance, are widely used in food packaging and agricultural greenhouses; EVA foam, due to its good cushioning and sound insulation properties, is widely used in electronic product packaging and sports shoe insoles. Therefore, the production and application of EVA are of great significance in promoting the development of related industries.

[0004] During the granulation process, functional antioxidants are typically added to maintain the color stability of EVA products and prevent oxidative degradation during storage and transportation. For example, Chinese patent application CN105542434A discloses a PU / EVA composite plastic material and its preparation method, whose raw materials include EVA and antioxidant 1076. However, antioxidant 1076 is a solid powder, and its addition generates a large amount of dust, which not only pollutes the environment but may also harm the health of operators. Therefore, in practical applications, appropriate measures need to be taken to reduce dust generation, such as using a closed addition system and wearing protective equipment. However, complete protection is difficult to achieve and may increase process costs and operational difficulty to some extent.

[0005] Therefore, how to further reduce the risks and costs in the production process while ensuring that EVA products have high antioxidant properties has become an urgent industry-wide technical problem that needs to be solved. Summary of the Invention

[0006] To address the aforementioned technical problems, the first aspect of this invention provides a liquid antioxidant, the raw materials for which include methyl propionate compound, catalyst, and small molecule polyol.

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

[0008] Furthermore, the structural formula of the methyl propionate compound is as follows:

[0009] Furthermore, the small molecule polyols include 1,2,6-hexanetriol.

[0010] Furthermore, the catalyst includes an alkali metal amine catalyst.

[0011] Furthermore, the alkali metal amine catalyst includes lithium amino.

[0012] Furthermore, the mass ratio of the methyl propionate compound to the catalyst is 1:(0.01-0.1).

[0013] As an implementable example, the method for preparing the liquid antioxidant includes:

[0014] S1. Mix methyl propionate compound and small molecule polyol, heat to 100-110℃ under vacuum, and dehydrate for 1-2 hours.

[0015] S2, then add the catalyst at 1 atm atmospheric pressure;

[0016] S3. Under vacuum conditions, heat to 155-160℃ and maintain the temperature for 3-5 hours.

[0017] S4. Under vacuum conditions, heat to 170-175℃ and maintain the temperature for 5-8 hours. After the reaction is complete, take a sample for analysis. When the content of methyl propylene ester compound is less than 1 wt%, filter, collect the liquid product, and purify it to obtain the liquid antioxidant.

[0018] A second aspect of the present invention provides an aging-resistant modified material, the raw materials for which preparation includes a substrate and the liquid antioxidant.

[0019] As an example of implementation, the mass ratio of the substrate to the liquid antioxidant is 100:(0.1-1).

[0020] As an example of implementation, the substrate includes one of PP, PE, PVC, EVA, PET, PA, and PBT.

[0021] Furthermore, the substrate is EVA.

[0022] A third aspect of the present invention provides a method for preparing an aging-resistant modified material, comprising:

[0023] The base material is added to a twin-screw extruder, and then a liquid antioxidant is pumped into the twin-screw extruder using a liquid metering pump. The mixture is then hot-melt extruded and granulated to obtain an aging-resistant modified material.

[0024] In traditional EVA material production, antioxidants are added during the manufacturing process to ensure superior anti-aging properties and stability during transportation and storage. These are typically phosphite oxidants, including antioxidant 1076. Antioxidant 1076 primarily inhibits oxidation by scavenging free radicals. When EVA products are exposed to external factors such as oxygen and light, free radicals are generated. These free radicals can trigger a chain reaction, leading to the production of more free radicals and accelerating the oxidation process. Antioxidant 1076 contains a p-cresol and propane skeleton and has two alkyl substituents, enabling it to react rapidly with free radicals and prevent further oxidation chain reactions, thus inhibiting the oxidation process.

[0025] However, during the feeding process of solid powder antioxidant 1076, a certain amount of dust will escape, polluting the production workshop environment and affecting the health of production personnel. More seriously, it may even cause serious safety accidents such as dust explosions. Therefore, in the process of modifying and preparing EVA, this invention creatively uses liquid antioxidants, especially the liquid products of methyl propionate compounds and small molecule polyols under the catalysis of amino lithium, which can effectively avoid the safety problems caused by solid powder antioxidants and improve the utilization rate of antioxidant raw materials.

[0026] Furthermore, compared to the traditional antioxidant 1076, the liquid antioxidant provided by this invention, when applied in EVA production, can impart superior resistance to yellowing and heat stability to the product. The inventors speculate that this is mainly because the liquid antioxidant molecule provided by this invention contains phenolic and alcoholic hydroxyl groups, which can act as hydrogen donors. These hydroxyl groups react with unstable free radicals generated during the thermal oxidation of polymer materials. By removing a hydrogen atom, the original free radicals can be eliminated, and the antioxidant itself can be transformed into a more stable free radical form, making it less likely to trigger new free radical chain reactions, thereby terminating the chain reaction and achieving highly efficient antioxidant and high-temperature yellowing resistance. Beneficial effects

[0027] (i) The liquid antioxidant provided by the present invention can be continuously added by a liquid metering pump, which avoids the dust pollution caused by the powder characteristics of the traditional solid antioxidant 1076, significantly reduces the risk of dust flash explosion at the production site, and simplifies the operation process, improves the accuracy and efficiency of addition.

[0028] (II) When the liquid oxidant provided by this invention is applied to the modification and processing of EVA, the average OIT (oxidation induction time) of the product is 15.62 minutes, which is significantly better than the 13.28 minutes of antioxidant 1076. This indicates that it can more effectively delay the oxidation of EVA materials and extend the storage stability and service life of the product.

[0029] (III) When the liquid oxidant provided by this invention is applied to the modification and processing of EVA, the product obtained after aging in an oven at 80°C for 168 hours has a YI (yellowing index) of only 1.1, which is much lower than the 2.1 of antioxidant 1076. Therefore, the liquid antioxidant provided by this 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.

[0030] (iv) The liquid antioxidant prepared by this invention can be precisely metered through a closed pipeline, avoiding the carbonization and black spot problems caused by the adhesion of traditional powder antioxidants 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.

[0031] (V) In this invention, the use of liquid antioxidants can effectively eliminate dust pollution, making the production site environment cleaner, reducing the risk of workers inhaling harmful dust, meeting occupational health and safety standards, and reducing equipment cleaning and maintenance costs. At the same time, experiments have shown that the liquid antioxidants provided by this invention have better antioxidant and aging resistance properties than similar liquid antioxidants on the market, including antioxidants 1135 and antioxidants 1315, when applied to the preparation of EVA. Attached Figure Description

[0032] Figure 1 is a schematic diagram of the high-temperature aging performance test of the modified material prepared in Example 1.

[0033] Figure 2 is a schematic diagram of the high-temperature aging performance test of the modified material prepared in Comparative Example 1. Detailed Implementation

[0034] Example 1

[0035] The first aspect of this example provides a liquid antioxidant, the raw materials for which, by mass parts, are specifically 35 parts of methyl propionate compound, 55 parts of 1,2,6-hexanetriol, and 1 part of aminolithium.

[0036] The structural formula of the methyl propionate compound is:

[0037] The specific method for preparing the liquid antioxidant is as follows:

[0038] S1. Mix the methyl propionate compound and 1,2,6-hexanetriol, add them to a four-necked flask equipped with a thermometer and a condenser, and heat to 105°C under a vacuum of -0.1 MPa for 1 hour to dehydrate.

[0039] S2, then add lithium amino acid at 1 atm;

[0040] Under vacuum conditions of S3 and -0.1 MPa, the temperature was raised to 160°C and the reaction was maintained at that temperature for 3 hours.

[0041] Under vacuum conditions of -0.1 MPa, the temperature was raised to 175°C and maintained for 7 hours. After the reaction was completed, samples were taken for analysis, and the content of methyl propylene ester compound was found to be less than 1 wt%. The product was filtered, collected, and purified to obtain the liquid antioxidant.

[0042] The second aspect of this example provides an aging-resistant modified material, the raw materials for which, by mass, are: 100 parts EVA and 0.5 parts liquid antioxidant.

[0043] The EVA mentioned was purchased from Jiangsu Sirbang Petrochemical Co., Ltd., and the model is V5120J.

[0044] The third aspect of this example provides a method for preparing an aging-resistant modified material, specifically as follows:

[0045] EVA is added to a twin-screw extruder, and then liquid antioxidant is pumped into the twin-screw extruder using a liquid metering pump. The mixture is then hot-melt extruded and granulated at 190°C to obtain an aging-resistant modified material.

[0046] Comparative Example 1

[0047] The first aspect of this example provides an aging-resistant modified material, the raw materials for which are prepared by mass parts are: 100 parts EVA and 0.5 parts solid antioxidant.

[0048] The EVA mentioned was purchased from Jiangsu Sirbang Petrochemical Co., Ltd., and the model is V5120J.

[0049] The solid antioxidant mentioned is antioxidant 1076 (CAS: 2082-79-3), purchased from BASF AG.

[0050] The second aspect of this example provides a method for preparing an aging-resistant modified material, specifically as follows:

[0051] EVA and antioxidant 1076 are added to a twin-screw extruder and hot-melt extrusion granulation is carried out at 190°C to obtain an aging-resistant modified EVA material.

[0052] Comparative Example 2

[0053] The first aspect of this example provides an aging-resistant modified material, the raw materials for which are prepared by mass parts are: 100 parts EVA and 0.5 parts liquid antioxidant.

[0054] The EVA mentioned was purchased from Jiangsu Sirbang Petrochemical Co., Ltd., and the model is V5120J.

[0055] The liquid antioxidant mentioned is antioxidant 1135 (CAS: 125643-61-0), purchased from BASF AG.

[0056] The second aspect of this example provides a method for preparing an aging-resistant modified material, specifically as follows:

[0057] EVA is added to a twin-screw extruder, and then antioxidant 1135 is pumped into the twin-screw extruder using a liquid metering pump. The mixture is then hot-melt extruded and granulated at 190°C to obtain an aging-resistant modified EVA material.

[0058] Comparative Example 3

[0059] The first aspect of this example provides an aging-resistant modified material, the raw materials for which are prepared by mass parts are: 100 parts EVA and 0.5 parts liquid antioxidant.

[0060] The EVA mentioned was purchased from Jiangsu Sirbang Petrochemical Co., Ltd., and the model is V5120J.

[0061] The liquid antioxidant mentioned is antioxidant 1315 (CAS: 171090-93-0), purchased from BASF AG.

[0062] The second aspect of this example provides a method for preparing an aging-resistant modified material, specifically as follows:

[0063] EVA is added to a twin-screw extruder, and then antioxidant 1315 is pumped into the twin-screw extruder using a liquid metering pump. The mixture is then hot-melt extruded and granulated at 190°C to obtain an aging-resistant modified EVA material.

[0064] Performance testing

[0065] I. Oxidation Induction Time (OIT) Test

[0066] Test subjects: the modified materials prepared in the examples and comparative examples 1-3.

[0067] Test method: Turn on the DSC device and calibrate it to ensure the accuracy of temperature and heat flow measurements. Connect nitrogen and oxygen, and check the gas flow rate and purity to ensure there is no impurity interference. Place the prepared modified material sample into the DSC sample tray and heat the sample to the predetermined temperature of 200℃ in a nitrogen atmosphere. After the sample reaches the predetermined temperature, switch to an oxygen atmosphere and maintain a constant temperature. Record the oxygen flow rate and switching time. Observe the changes in the heat flow signal through the DSC curve to determine the time point when the oxidation reaction begins, i.e., the time when the heat flow signal rises significantly. Record this time as the oxidation induction time. Test each sample twice and calculate the average OIT. The test results are detailed in Table 1.

[0068] Table 1

[0069] As can be seen from the experimental results in Table 1, the liquid antioxidant provided by this invention has a longer OIT value when applied to EVA modification compared to comparative examples 1-3, indicating that the liquid antioxidant provided by this invention can extend the storage performance and physical stability of the product.

[0070] II. Yellowing Index Test

[0071] Test subjects: the modified materials prepared in the examples and comparative examples 1-3.

[0072] Test method: Refer to ASTM E313 method to test the yellowing index of the modified material at room temperature (25°C). The experimental results are detailed in Table 2.

[0073] Table 2

[0074] Experimental results show that the liquid antioxidant provided by this invention has a certain degree of improvement in yellowing resistance compared with antioxidant 1076 after application.

[0075] III. High-Temperature Aging Performance Test

[0076] Test subjects: the modified materials prepared in the examples and comparative examples 1-3.

[0077] Test method: The modified EVA material was aged in an oven at 80℃ for 168h. The color of the modified material was then observed and the yellowing index was tested. The experimental results are shown in Figure 1-2 and Table 3.

[0078] Table 3

[0079] Experimental results show that, based on the color comparison of the products, the liquid antioxidant provided by this invention provides significantly better high-temperature aging protection for the products than antioxidant 1076, and its actual application effect is even better.

Claims

1. A liquid antioxidant, characterized in that, The raw materials for preparation include methyl propionate compounds, catalysts, and small molecule polyols.

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 polyols mentioned include 1,2,6-hexanetriol.

5. The liquid antioxidant according to claim 1, characterized in that, The catalysts mentioned include alkali metal amine catalysts.

6. The liquid antioxidant according to claim 5, characterized in that, The alkali metal amine catalysts include lithium amino groups.

7. An aging-resistant modified material, characterized in that, The raw materials for preparation include a substrate and the liquid antioxidant as described in any one of claims 1-6.

8. The aging-resistant modified material according to claim 7, characterized in that, The mass ratio of the substrate 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 7-9, characterized in that, include: The base material is added to a twin-screw extruder, and then a liquid antioxidant is pumped into the twin-screw extruder using a liquid metering pump. The mixture is then hot-melt extruded and granulated to obtain an aging-resistant modified material.

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