Intramolecular synergistic antioxidant, polypropylene cable material and preparation method thereof

Abstract

The application discloses an intramolecular synergistic antioxidant, a polypropylene cable material and a preparation method thereof, and relates to the technical field of wires and cables.The application provides an intramolecular synergistic antioxidant which has a hindered phenol group and a thioether group, combines the advantages of a hindered phenol antioxidant and a sulfur antioxidant, and can improve the antioxidation capacity of a material through synergistic action of the two.The application prepares a polypropylene cable material by using the prepared intramolecular synergistic antioxidant, the cable material prepared by the application has excellent mechanical properties and high-temperature heat aging resistance, maintains the insulation properties of the polypropylene cable material, and has a simple preparation process and a large application prospect.

Description

Technical Field

[0001] This invention relates to the field of wire and cable technology, and in particular to an intramolecular synergistic antioxidant, polypropylene cable material, and their preparation method. Background Technology

[0002] Cross-linked polyethylene (XLPE) insulated cables can no longer meet the needs of modern green and sustainable socio-economic development. Developing thermoplastic insulated cables that can replace XLPE insulation is an important direction for the development of power cables. Power cables with thermoplastic materials as the main insulation can be recycled after their service life, meeting the environmental protection requirements of sustainable development. Furthermore, thermoplastic materials do not require cross-linking agents in the cable production process, reducing by-products and impurities introduced by cross-linking, thereby simplifying the production process.

[0003] Polypropylene, one of the five major general-purpose plastics, is a common thermoplastic material with a melting temperature exceeding 150℃, more than 40% higher than polyethylene. It can operate continuously at 90℃. This excellent high-temperature resistance is crucial for improving the operating temperature and voltage rating of power cables. Furthermore, polypropylene does not require cross-linking in high-temperature environments, and cables can be recycled and re-thermoplasticized after long-term use, aligning with global environmental trends. Therefore, current researchers primarily use physical blending or chemical modification methods to improve polypropylene properties, but these methods still have certain limitations.

[0004] Studies have shown that the presence of tertiary carbon atoms in the polypropylene structure makes it susceptible to free radical generation under the influence of heat, oxygen, and light, leading to chain-to-chain free radical reactions and causing polypropylene aging and deterioration. During thermo-oxidative aging, polypropylene molecular chains break and degrade, resulting in a decrease in molecular weight and melt viscosity, thus reducing polypropylene strength. Furthermore, peroxides and other oxidizing agents generated during thermo-oxidative aging reduce the insulation properties of polypropylene and increase its sensitivity to photo-induced degradation. Therefore, these environmental factors affect the performance and usability of polypropylene. The addition of antioxidants can improve the antioxidant capacity of polypropylene, thereby enhancing its heat aging resistance. However, compared to polypropylene itself, antioxidants are generally highly polar substances, which can reduce the material's insulation properties.

[0005] Therefore, research on polypropylene cable insulation materials is of great significance. Improving the high-temperature aging resistance of polypropylene while maintaining its high insulation performance is a major challenge. Summary of the Invention

[0006] Based on this, the purpose of the present invention is to overcome the shortcomings of the prior art and provide an intramolecular synergistic antioxidant, polypropylene cable material and its preparation method.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: an intramolecular synergistic antioxidant, wherein the structural formula of the intramolecular synergistic antioxidant is shown in the following formula (I), wherein R is one of formula (II), formula (III), and formula (IV);

[0008]

[0009] Hindered phenolic antioxidants can capture peroxide free radicals, interrupting the diffusion of free radical chain reactions, while sulfur-based antioxidants can decompose hydroperoxides, terminating free radical formation at its source. The intramolecular synergistic antioxidant prepared in this invention possesses both hindered phenolic and thioether groups, combining the advantages of both. Their synergistic effect enhances the material's antioxidant capacity. Furthermore, this intramolecular synergistic antioxidant has a symmetrical molecular structure and low polarity, preventing deterioration of the material's insulation properties. Compared to commonly used hindered phenolic and sulfur-based antioxidants, the intramolecular synergistic antioxidant prepared in this invention significantly increases the oxidation induction period and volume resistivity of the material at the same dosage, demonstrating superior performance.

[0010] Preferably, the present invention provides a method for preparing the aforementioned intramolecular synergistic antioxidant, comprising the following steps:

[0011] S1. Dissolve the hindered phenolic olefin compound in an organic solvent to obtain mixture A;

[0012] S2. Mix ethylene glycol dithiocarbamate, a tertiary amine catalyst and an organic solvent evenly to obtain mixture B;

[0013] S3. Mix mixture A and mixture B evenly, and after reaction, the intramolecular synergistic antioxidant is obtained.

[0014] Preferably, the molar ratio of the hindered phenolic olefin compound to ethylene glycol dimercaptoacetate is 2:1.

[0015] Preferably, in S1, the mass ratio of hindered phenolic olefin compound to organic solvent is hindered phenolic olefin compound: organic solvent = 1:(5-10); in S2, the molar ratio of ethylene glycol dimercaptoacetate to tertiary amine catalyst is ethylene glycol dimercaptoacetate: tertiary amine catalyst = 100:(1-5), and the mass ratio of ethylene glycol dimercaptoacetate to organic solvent is ethylene glycol dimercaptoacetate: organic solvent = 1:(5-10).

[0016] Preferably, the hindered phenolic olefin compound is at least one of 2,6-di-tert-butyl-4-vinylphenol, 2,6-di-tert-butyl-4-allylphenol, and 2-tert-butyl-6-(2-hydroxy-3-tert-butyl-5-methylphenyl)methyl-4-methylphenyl acrylate; the organic solvent is at least one of tetrahydrofuran and N,N'-dimethylformamide; and the tertiary amine catalyst is at least one of triethylamine and N,N'-dimethylpyridine.

[0017] Preferably, in step S3, the reaction temperature is 40-80℃ and the reaction time is 2-16h.

[0018] Furthermore, this invention provides the application of the aforementioned intramolecular synergistic antioxidant in the preparation of polypropylene cable materials.

[0019] Furthermore, the present invention provides a polypropylene cable material comprising the following components in parts by weight: 25-45 parts homopolymer polypropylene, 25-45 parts copolymer polypropylene, 25-45 parts ethylene-octene copolymer, 0.1-1 parts ultraviolet light absorber, 0.1-1 parts light stabilizer, and 0.1-1 parts of the intramolecular synergistic antioxidant.

[0020] This invention utilizes the intramolecular synergistic antioxidant prepared above to prepare polypropylene cable material. In this invention, homopolymer polypropylene, copolymer polypropylene, ethylene-octene copolymer, ultraviolet light absorber, light stabilizer, and intramolecular synergistic antioxidant are all components of the polypropylene cable material, and each component works synergistically with the others. Homopolymer polypropylene is used to maintain the overall strength and melting point of the material; copolymer polypropylene is used to improve the material's impact resistance; ethylene-octene copolymer is used to improve the material's toughness and maintain volume resistivity; and ultraviolet light absorber and light stabilizer are used to improve resistance to ultraviolet light. The addition of the intramolecular synergistic antioxidant can significantly improve the material's resistance to high-temperature thermal aging without significantly reducing the material's insulation performance, and a high-performance polypropylene cable material can be obtained without requiring a very high addition amount.

[0021] The cable material prepared by this invention has excellent mechanical properties and high-temperature thermal aging resistance, while maintaining the insulation properties of polypropylene cable material. Furthermore, the preparation process is simple and has great application prospects.

[0022] Preferably, the melt flow rate of the homopolymer polypropylene is ≤3.5g / 10min, and the test conditions are 230℃ / 2.16kg; the melt flow rate of the copolymer polypropylene is ≤2.5g / 10min, and the test conditions are 230℃ / 2.16kg; the α-olefin mass fraction of the ethylene-octene copolymer is 20%-35%.

[0023] More preferably, the ethylene-octene copolymer is at least one of POE 8150, POE 6202, POE 3980, and POE 2070.

[0024] Preferably, the ultraviolet light absorber is at least one of UV329, UV326, and C81, and the light stabilizer is UV770.

[0025] Preferably, the present invention provides a method for preparing the polypropylene cable material, comprising the following steps:

[0026] (1) Put all the above raw materials into the mixer and mix them evenly;

[0027] (2) The uniformly mixed material is fed into a twin-screw extruder, extruded and granulated, and then dried to obtain the polypropylene cable material.

[0028] Preferably, the extruder heating zones in S2 are as follows: Zone 1: 100-140℃, Zone 2: 175-215℃, Zone 3: 175-215℃, Zone 4: 180-220℃, Zone 5: 180-220℃, Zone 6: 180-220℃, Zone 7: 175-215℃, Zone 8: 175-215℃, Zone 9: 180-220℃, Zone 10: 180-220℃, and the screw speed is 150-350 r / min.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] The intramolecular synergistic antioxidant prepared by this invention possesses hindered phenolic and thioether groups, combining the advantages of hindered phenolic antioxidants and sulfur-based antioxidants. Their synergistic effect enhances the antioxidant capacity of the material. Furthermore, this intramolecular synergistic antioxidant has a symmetrical molecular structure and low polarity, thus not deteriorating the insulation performance of the material. Compared to commonly used hindered phenolic and sulfur-based antioxidants, the intramolecular synergistic antioxidant prepared by this invention significantly increases the oxidation induction period and volume resistivity of the material at the same dosage, demonstrating superior performance.

[0031] This invention utilizes the intramolecular synergistic antioxidant prepared above to prepare polypropylene cable material. In this invention, homopolymer polypropylene, copolymer polypropylene, ethylene-octene copolymer, ultraviolet light absorber, light stabilizer, and intramolecular synergistic antioxidant are all components of the polypropylene cable material, and each component works synergistically with the others. Homopolymer polypropylene is used to maintain the overall strength and melting point of the material; copolymer polypropylene is used to improve the material's impact resistance; ethylene-octene copolymer is used to improve the material's toughness and maintain volume resistivity; and ultraviolet light absorber and light stabilizer are used to improve resistance to ultraviolet light. The addition of the intramolecular synergistic antioxidant can significantly improve the material's resistance to high-temperature thermal aging without significantly reducing the material's insulation performance, and a high-performance polypropylene cable material can be obtained without requiring a very high addition amount.

[0032] The cable material prepared by this invention has excellent mechanical properties and high-temperature thermal aging resistance, while maintaining the insulation properties of polypropylene cable material. Furthermore, the preparation process is simple and has great application prospects. Attached Figure Description

[0033] Figure 1 The infrared spectrum of intramolecular synergistic antioxidant-1;

[0034] Figure 2 A reaction mechanism diagram of intramolecular synergistic antioxidant-1;

[0035] Figure 3 A reaction mechanism diagram of intramolecular synergistic antioxidant-8;

[0036] Figure 4 This is a reaction mechanism diagram of intramolecular synergistic antioxidant-9. Detailed Implementation

[0037] To better illustrate the purpose, technical solution, and advantages of this invention, the invention will be further described below in conjunction with the accompanying drawings and specific embodiments. The purpose is to provide a detailed understanding of the invention, not to limit it. All other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention. Unless otherwise specified, the experimental reagents and instruments designed in the embodiments and comparative examples of this invention are commonly used reagents and instruments, all of which are commercially available. Unless otherwise specified, the experimental methods used in the embodiments and comparative examples are conventional methods; and unless otherwise specified, the raw materials used in parallel experiments are from the same batch.

[0038] The main raw materials used in the embodiments and comparative examples of this invention are described below, as shown in Table 1, but are not limited to these materials:

[0039] Homopolymer polypropylene-1: melt flow rate 3.4 g / 10 min (230℃ / 2.16 kg), T30S, Fujian United;

[0040] Homopolymer polypropylene-2: melt flow rate 1.5 g / 10 min (230℃ / 2.16 kg), RB707CF, Borouge Chemicals;

[0041] Copolymer polypropylene-1: melt flow rate 1.9 g / 10 min (230℃ / 2.16 kg), PPB-M02, Yangzi Petrochemical;

[0042] Copolymer polypropylene-2: melt flow rate 2.5 g / 10 min (230℃ / 2.16 kg), Yanshan Petrochemical;

[0043] Ethylene-octene copolymer: POE8150, Yangzi Petrochemical;

[0044] UV absorber: UV329, commercially available;

[0045] Light stabilizer: UV 770, commercially available;

[0046] Intramolecular synergistic antioxidant-1: In-house prepared as follows: 0.01 mol of 2,6-di-tert-butyl-4-vinylphenol was dissolved in 23.2 g of tetrahydrofuran; simultaneously, 0.005 mol of ethylene glycol dimercaptoacetate, 0.05 g of triethylamine, and 10.5 g of tetrahydrofuran were mixed thoroughly. The two were reacted at 60 °C under a nitrogen atmosphere. After 8 hours of reaction, the reaction solution was distilled under reduced pressure, washed with water, and dried to obtain intramolecular synergistic antioxidant-1 with a yield of 75.7%.

[0047] Intramolecular synergistic antioxidant-2: self-made, the preparation method is as follows: the difference from intramolecular synergistic antioxidant-1 is that the reaction solvent is changed from tetrahydrofuran to N,N'-dimethylformamide.

[0048] First, 0.01 mol of 2,6-di-tert-butyl-4-vinylphenol was dissolved in 23.2 g of N,N'-dimethylformamide; simultaneously, 0.005 mol of ethylene glycol dimercaptoacetate, 0.05 g of triethylamine, and 10.5 g of N,N'-dimethylformamide were mixed thoroughly. The two were reacted at 60 °C under a nitrogen atmosphere. After a certain reaction time of 8 h, the reaction solution was distilled under reduced pressure, washed with water, and dried to obtain intramolecular synergistic antioxidant-2 with a yield of 73.2%.

[0049] Intramolecular synergistic antioxidant-3: self-made, the preparation method is as follows: the difference from intramolecular synergistic antioxidant-1 is that the reaction time has been changed.

[0050] First, 0.01 mol of 2,6-di-tert-butyl-4-vinylphenol was dissolved in 23.2 g of tetrahydrofuran; simultaneously, 0.005 mol of ethylene glycol dimercaptoacetate, 0.05 g of triethylamine, and 10.5 g of tetrahydrofuran were mixed thoroughly. The two were reacted at 60 °C under a nitrogen atmosphere. After a reaction time of 4 h, the reaction solution was distilled under reduced pressure, washed with water, and dried to obtain intramolecular synergistic antioxidant-3 with a yield of 45.7%.

[0051] Intramolecular synergistic antioxidant-4: self-made, the preparation method is as follows: unlike intramolecular synergistic antioxidant-1, the reaction time is further changed.

[0052] First, 0.01 mol of 2,6-di-tert-butyl-4-vinylphenol was dissolved in 23.2 g of tetrahydrofuran; simultaneously, 0.005 mol of ethylene glycol dimercaptoacetate, 0.05 g of triethylamine, and 10.5 g of tetrahydrofuran were mixed thoroughly. The two were reacted at 60 °C under a nitrogen atmosphere. After a reaction time of 12 h, the reaction solution was distilled under reduced pressure, washed with water, and dried to obtain intramolecular synergistic antioxidant-4 with a yield of 76.2%.

[0053] Intramolecular synergistic antioxidant-5: self-made, preparation method as follows: Unlike intramolecular synergistic antioxidant-1, the reaction temperature was changed.

[0054] First, 0.01 mol of 2,6-di-tert-butyl-4-vinylphenol was dissolved in 23.2 g of tetrahydrofuran; simultaneously, 0.005 mol of ethylene glycol dimercaptoacetate, 0.05 g of triethylamine, and 10.5 g of tetrahydrofuran were mixed thoroughly. The two were reacted at 40 °C under a nitrogen atmosphere. After 8 hours of reaction, the reaction solution was distilled under reduced pressure, washed with water, and dried to obtain intramolecular synergistic antioxidant-5 with a yield of 55.7%.

[0055] Intramolecular synergistic antioxidant-6: self-made, preparation method as follows: Unlike intramolecular synergistic antioxidant-1, the reaction temperature is further changed.

[0056] First, 0.01 mol of 2,6-di-tert-butyl-4-vinylphenol was dissolved in 23.2 g of tetrahydrofuran; simultaneously, 0.005 mol of ethylene glycol dimercaptoacetate, 0.05 g of triethylamine, and 10.5 g of tetrahydrofuran were mixed thoroughly. The two were reacted at 80 °C under a nitrogen atmosphere. After 8 hours of reaction, the reaction solution was distilled under reduced pressure, washed with water, and dried to obtain intramolecular synergistic antioxidant-6 with a yield of 47.7%.

[0057] Intramolecular synergistic antioxidant-7: self-made, preparation method as follows: Unlike intramolecular synergistic antioxidant-1, the tertiary amine catalyst used in the reaction is changed from triethylamine to N,N'-dimethylpyridine.

[0058] First, 0.01 mol of 2,6-di-tert-butyl-4-vinylphenol was dissolved in 23.2 g of tetrahydrofuran; simultaneously, 0.005 mol of ethylene glycol dimercaptoacetate, 0.055 g of N,N'-dimethylpyridine, and 10.5 g of tetrahydrofuran were mixed thoroughly. The two were reacted at 60 °C under a nitrogen atmosphere. After a certain reaction time of 8 h, the reaction solution was distilled under reduced pressure, washed with water, and dried to obtain intramolecular synergistic antioxidant-7 with a yield of 46.2%.

[0059] The preparation of intramolecular synergistic antioxidants-1 to-7 yielded identical intramolecular synergistic antioxidants, differing only in yield. The infrared spectra of intramolecular synergistic antioxidants-1 to-7 are shown below. Figure 1 As shown, the wavenumber is 3591.1 cm⁻¹. -1 This is the stretching vibration peak of the free phenolic hydroxyl group on the benzene ring, at 2954.2 cm⁻¹. -1 and 2914.1cm -1 Nearby are the symmetric and antisymmetric stretching vibration peaks of the methylene and methyl groups, at 1734.1 cm⁻¹. -1 The peak at 1434.7 cm⁻¹ represents the stretching vibration characteristic of the carbonyl group. -1 This is a characteristic peak of the skeletal vibration in the benzene ring. 1378.6 cm⁻¹ -1 The peak represents the stretching vibration of the methyl group on the tert-butyl group, at 1147.0 cm⁻¹. -1 The peak value is the stretching vibration peak of COC, at 768.5 cm⁻¹. -1 and 873.9cm -1 The peak is a characteristic peak of tetrasubstituted benzene ring, at 642.9 cm⁻¹. -1 These are characteristic stretching peaks of CSC in sulfides.

[0060] Intramolecular synergistic antioxidant-8: self-made, prepared as follows: First, dissolve 0.01 mol of 2,6-di-tert-butyl-4-allylphenol in 24.6 g of tetrahydrofuran; simultaneously, mix 0.005 mol of ethylene glycol dimercaptoacetate, 0.05 g of triethylamine, and 10.5 g of tetrahydrofuran evenly. The two are reacted at 60 °C under a nitrogen atmosphere. After 8 hours of reaction, the reaction solution is distilled under reduced pressure, washed with water, and dried to obtain intramolecular synergistic antioxidant-8.

[0061] Intramolecular synergistic antioxidant-9: Self-made, prepared as follows: First, 0.01 mol of 2-tert-butyl-6-(2-hydroxy-3-tert-butyl-5-methylphenyl)methyl-4-methylphenyl acrylate was dissolved in 39.4 g of tetrahydrofuran; simultaneously, 0.005 mol of ethylene glycol dimercaptoacetate, 0.05 g of triethylamine, and 10.5 g of tetrahydrofuran were mixed evenly. The two were reacted at 60 °C under a nitrogen atmosphere. After 8 hours of reaction, the reaction solution was distilled under reduced pressure, washed with water, and dried to obtain intramolecular synergistic antioxidant-9.

[0062] Intramolecular synergistic antioxidant-1, intramolecular synergistic antioxidant-8, and intramolecular synergistic antioxidant-9 have different structures. The reaction mechanism of intramolecular synergistic antioxidant-1 is as follows: Figure 2 As shown, the reaction mechanism of intramolecular cooperative antioxidant-8 is as follows: Figure 3 As shown, the reaction mechanism of intramolecular cooperative antioxidant-9 is as follows: Figure 4 As shown.

[0063] Examples and Comparative Examples

[0064] Example 1

[0065] A polypropylene cable material comprises the following components in parts by weight: 34 parts homopolymer polypropylene-1, 134 parts copolymer polypropylene-1, 30 parts ethylene-octene copolymer POE8150, 0.5 parts ultraviolet light absorber UV329, 0.5 parts light stabilizer UV770, and 0.5 parts intramolecular synergistic antioxidant-1.

[0066] This invention provides a polypropylene cable material, and the preparation method of the polypropylene cable material includes the following steps:

[0067] S1: Add the above raw materials into the mixer and mix evenly;

[0068] S2: The uniformly mixed material is fed into a twin-screw extruder, extruded and pelletized, and then dried to obtain the polypropylene cable material. The set temperature of the twin-screw extruder is: Zone 1: 140℃, Zone 2: 175℃, Zone 3: 215℃, Zone 4: 220℃, Zone 5: 220℃, Zone 6: 220℃, Zone 7: 215℃, Zone 8: 215℃, Zone 9: 220℃, Zone 10: 220℃, and the screw speed is 350 r / min.

[0069] Example 2

[0070] A polypropylene cable material, the only difference from Example 1 is the use of homopolymer polypropylene-2, while the other components, weight parts and preparation methods are exactly the same.

[0071] Example 3

[0072] A polypropylene cable material, the only difference from Example 1 is the use of copolymer polypropylene-2, while the other components, weight parts and preparation methods are exactly the same.

[0073] Example 4

[0074] A polypropylene cable material, the only difference from Example 1 is the use of intramolecular synergistic antioxidant-8, while the other components, weight parts and preparation methods are exactly the same.

[0075] Example 5

[0076] A polypropylene cable material, the only difference from Example 1 is the use of intramolecular synergistic antioxidant-9, while the other components, weight parts and preparation methods are exactly the same.

[0077] Comparative Example 1

[0078] A polypropylene cable material, the only difference from Example 1 is that 2,6-di-tert-butyl-4-vinylphenol is used to replace the intramolecular synergistic antioxidant-1, while the components, weight parts and preparation method are exactly the same.

[0079] Comparative Example 2

[0080] A polypropylene cable material, the only difference from Example 1 is that 2,6-di-tert-butyl-4-allylphenol is used to replace the intramolecular synergistic antioxidant-1, while the components, weight parts and preparation method are exactly the same.

[0081] Comparative Example 3

[0082] A polypropylene cable material, the only difference from Example 1, is that 2-tert-butyl-6-(2-hydroxy-3-tert-butyl-5-methylphenyl)methyl-4-methylphenyl acrylate is used to replace the intramolecular synergistic antioxidant-1. The components, parts by weight and preparation method are exactly the same.

[0083] Comparative Example 4

[0084] A polypropylene cable material, the only difference from Example 1 is that antioxidant 1076 is used instead of intramolecular synergistic antioxidant-1, while the components, weight parts and preparation method are exactly the same.

[0085] Comparative Example 5

[0086] A polypropylene cable material, the only difference from Example 1 is that antioxidant 1010 is used instead of intramolecular synergistic antioxidant-1, while the components, weight parts and preparation method are exactly the same.

[0087] Performance testing

[0088] 1. Volume resistivity at 20℃: T / SHPTA 014.1-2021;

[0089] 2. Oxidation induction period at 210℃: GB / T 19466.6-2009;

[0090] 3. Change rate of tensile strength under heat aging at 150℃ / 168h: T / SHPTA 014.1-2021;

[0091] 4. Change rate of elongation at break after heat aging at 150℃ / 168h: T / SHPTA 014.1-2021.

[0092] The performance test results are shown in Table 2.

[0093] Table 2

[0094]

[0095]

[0096] As shown in the table above, the polypropylene cable material prepared by the examples exhibits excellent mechanical properties. Its tensile strength and elongation at break are significantly higher than the relevant specifications in standard T / SHPTA 014.1-2021. Its high-temperature heat aging resistance is significantly increased, far exceeding the requirement in standard T / SHPTA 014.1-2021 that after aging at 150℃ for 168 hours, the retained values ​​of strength and elongation at break should not be less than 25% of the original values. This demonstrates the excellent performance and indicates that the polypropylene cable material prepared by this invention has strong resistance to high-temperature heat aging. Furthermore, compared to comparative examples 1-5, the polypropylene cable material prepared by the examples shows a significantly increased oxidation induction period, indicating that the polypropylene cable material prepared by this invention has strong resistance to thermal oxidation. The polypropylene cable material prepared by the examples also retains a relatively high volume resistivity at 10... 17 The value is on the order of Ω·cm, higher than the 20℃ volume resistivity of 10 in standard T / SHPTA 014.1-2021. 16 The order of magnitude and excellent performance indicate that the polypropylene cable material prepared by this invention maintains high insulation performance.

[0097] Comparing Examples 1 and 4, the change rates of tensile strength and elongation at break after aging in Example 1 are slightly higher than those in Example 4. This is because the thioether in the intramolecular synergistic antioxidant can catalyze the decomposition of hydroperoxides produced during aging, oxidizing them to sulfoxide groups or sulfonyl groups. Both of these groups are electron-withdrawing substituents, which greatly reduces the activity of hindered phenols. In Example 1, the sulfur atom of the intramolecular synergistic antioxidant 1 is closer to the hindered phenol, thus reducing its activity to some extent. Comparing Examples 4 and 5, the change rates of tensile strength and elongation at break after aging in Example 4 are slightly higher than those in Example 5. This is because the sulfur atom of the intramolecular synergistic antioxidant 9 in Example 5 is further away from the hindered phenol than that of the intramolecular synergistic antioxidant 8, thus having a lower impact on the activity of hindered phenols. Furthermore, the steric hindrance at the sulfur atom is relatively small, making it easier to react with hydroperoxides to form stable compounds, resulting in better heat aging resistance.

[0098] In summary, the cable material prepared by this invention possesses excellent mechanical properties and resistance to high-temperature thermal aging. While improving toughness and resistance to thermo-oxidative aging, it also maintains the insulation properties of polypropylene cable material. Furthermore, the preparation process is simple and has significant application prospects.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A polypropylene cable compound, characterized in that, Components including the following weight parts: homopolymer polypropylene 25-45 parts, copolymer polypropylene 25-45 parts, ethylene-octene copolymer 25-45 parts, ultraviolet light absorber 0.1-1 part, light stabilizer 0.1-1 part, intramolecular synergistic antioxidant 0.1-1 part; The structural formula of the intramolecular synergistic antioxidant is shown in the following formula (I), wherein R is one of formula (II), formula (III), formula (IV); Formula (I) Formula (II) Formula (III) Formula (IV).

2. The polypropylene cable compound of claim 1, wherein, The preparation method of the intramolecular synergistic antioxidant comprises the following steps: S1, dissolving the hindered phenol alkene compound in an organic solvent to obtain a mixed liquid A; S2, mixing diethyleneglycol bismercapate and tertiary amine catalyst with the organic solvent uniformly, and reacting to obtain a mixed liquid B; S3, mixing the mixed liquid A and the mixed liquid B uniformly, and obtaining the intramolecular synergistic antioxidant after reaction.

3. The polypropylene cable compound of claim 2, wherein, In the S1, the mass ratio of the hindered phenol alkene compound and the organic solvent is hindered phenol alkene compound: organic solvent = 1: (5-10); in the S2, the molar ratio of diethyleneglycol bismercapate and tertiary amine catalyst is diethyleneglycol bismercapate: tertiary amine catalyst = 100: (1-5), and the mass ratio of diethyleneglycol bismercapate and the organic solvent is diethyleneglycol bismercapate: organic solvent = 1: (5-10).

4. The polypropylene cable material according to claim 2, characterized in that The hindered phenol alkene compound is at least one of 2, 6-di-tert-butyl-4-vinylphenol, 2, 6-di-tert-butyl-4-allylphenol, 2-tert-butyl-6-(2-hydroxy-3-tert-butyl-5-methylphenyl)methyl-4-methylphenyl acrylate; the organic solvent is at least one of tetrahydrofuran, N, N'-dimethylformamide; and the tertiary amine catalyst is at least one of triethylamine, N , N’ dimethylpyridine.

5. The polypropylene cable material according to claim 1, wherein The melt flow rate of the homopolymer polypropylene is ≤3.5 g / 10 min, and the test condition is 230℃ / 2.16 kg; the melt flow rate of the copolymer polypropylene is ≤2.5 g / 10 min, and the test condition is 230℃ / 2.16 kg; the mass fraction of alpha-olefin of the ethylene-octene copolymer is 20%-35%.

6. A process for the production of a polypropylene cable material according to any one of claims 1 to 5, characterized in that Comprising the following steps: (1) putting the above raw materials into a mixer and mixing uniformly; (2) putting the uniformly mixed material into a double-screw extruder, extruding and pelletizing, drying, and obtaining the polypropylene cable material.

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