Intramolecular synergistic antioxidant, polypropylene cable material and preparation method thereof

Abstract

The invention 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 intramolecular synergistic antioxidant provided by the invention has hindered phenol groups and thioether groups, the advantages of hindered phenol antioxidants and sulfur antioxidants are combined, and the hindered phenol antioxidants and the sulfur antioxidants have a synergistic effect, so that the oxidation resistance of a material can be improved together. The polypropylene cable material is prepared by applying the prepared intramolecular synergistic antioxidant, the prepared cable material has excellent mechanical property and high temperature and thermal aging resistance, the insulating property of the polypropylene cable material is also maintained, the preparation process is simple, and the cable material has a relatively large application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of electric wires and cables, in particular to an intramolecular synergistic antioxidant, a polypropylene cable material and a preparation method thereof. Background Art

[0002] Cross-linked polyethylene (XLPE) insulated cables can no longer meet the needs of green and sustainable contemporary social and economic development. The development of 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 expires, meeting the environmental protection requirements of sustainable development. In addition, 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] As one of the five general-purpose plastics, polypropylene is a common thermoplastic material. Its melting temperature can reach over 150°C, which is more than 40% higher than that of polyethylene materials. It can work continuously in an environment of 90°C. The excellent high temperature resistance of polypropylene is of great significance to improving the working temperature of power cables and increasing the voltage level. Furthermore, polypropylene does not require cross-linking when used in high temperature environments, and the cables can still be recycled and thermoformed again after long-term use, which is in line with the global environmental protection trend. Therefore, researchers currently mainly choose physical blending or chemical modification methods to improve the performance of polypropylene, but there are still certain shortcomings.

[0004] Studies have shown that due to the presence of tertiary carbon atoms in the structure of polypropylene, it is easy to be affected by heat, oxygen, and light to produce free radicals, and then free radical reactions between chains occur, causing polypropylene to age and deteriorate. During the thermal oxidative aging process, the polypropylene molecular chain breaks and degrades, the molecular weight decreases, and the melt viscosity decreases, resulting in a decrease in the strength of polypropylene. In addition, oxidative structural substances such as peroxides generated during thermal oxidative aging will reduce the insulation properties of polypropylene and increase the sensitivity to light-induced degradation. Therefore, these environmental factors will affect the performance and use value of polypropylene. The addition of antioxidants can improve the antioxidant capacity of polypropylene, thereby enhancing its heat aging resistance. However, compared with polypropylene itself, antioxidants are generally more polar substances, which will reduce the insulation properties of the material.

[0005] Therefore, it is of great significance to study polypropylene cable insulation materials. It is a great challenge to improve the high temperature aging resistance of polypropylene while maintaining its high insulation performance. Summary of the invention

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

[0007] To achieve the above object, the technical solution adopted by the present invention is: an intramolecular synergistic antioxidant, 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 phenol antioxidants can capture peroxide free radicals and interrupt the diffusion of free radical chain reactions, while sulfur antioxidants can decompose hydroperoxides and terminate the formation of free radicals from the source. The intramolecular synergistic antioxidant prepared by the present invention has a hindered phenol group and a thioether group, and combines the advantages of hindered phenol antioxidants and sulfur antioxidants. The two work synergistically and can jointly improve the antioxidant capacity of the material. At the same time, the intramolecular synergistic antioxidant is a symmetrical molecular structure with low polarity, and will not deteriorate the insulating properties of the material. Moreover, the intramolecular synergistic antioxidant prepared by the present invention can significantly increase the oxidation induction period and volume resistivity of the material at the same addition amount compared with the commonly used hindered phenol antioxidants and sulfur antioxidants, and the intramolecular synergistic antioxidant prepared by the present invention has a better effect.

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

[0011] S1, dissolving the hindered phenol olefin compound in an organic solvent to obtain a mixed solution A;

[0012] S2, mixing ethylene glycol bis(thioglycolate), a tertiary amine catalyst and an organic solvent uniformly, and reacting to obtain a mixed solution B;

[0013] S3, mixing the mixed solution A and the mixed solution B evenly, and obtaining the intramolecular synergistic antioxidant after reaction.

[0014] Preferably, the molar ratio of the hindered phenol olefin compound to ethylene glycol bis(thioglycolate) is 2:1.

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

[0016] Preferably, the hindered phenol 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 S3, the reaction temperature is 40-80° C., and the reaction time is 2-16 h.

[0018] In addition, the present invention provides the use of the 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 of homopolypropylene, 25-45 parts of copolymer polypropylene, 25-45 parts of ethylene-octene copolymer, 0.1-1 parts of ultraviolet light absorber, 0.1-1 parts of light stabilizer, and 0.1-1 parts of the intramolecular synergistic antioxidant.

[0020] The present invention uses the above-prepared intramolecular synergistic antioxidant to prepare a polypropylene cable material. In the present invention, homopolypropylene, copolymer polypropylene, ethylene-octene copolymer, ultraviolet light absorber, light stabilizer and intramolecular synergistic antioxidant are used as components of the polypropylene cable material, and each component cooperates with each other. Homopolypropylene is used to maintain the overall strength and melting point of the material, copolymer polypropylene is used to improve the impact resistance of the material, ethylene-octene copolymer is used to improve the toughness of the material and maintain the volume resistivity, and ultraviolet light absorber and light stabilizer are used to improve the resistance to ultraviolet light. The addition of the intramolecular synergistic antioxidant can significantly improve the material's resistance to high temperature thermal aging, will not significantly reduce the material's insulation performance, and does not require a very high addition amount to obtain a polypropylene cable material with excellent performance.

[0021] The cable material prepared by the invention has excellent mechanical properties and high temperature heat aging resistance, and also maintains the insulation performance of the polypropylene cable material, and the preparation process is simple, and has great application prospects.

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

[0023] Further 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 a mixer and mix them evenly;

[0027] (2) The uniformly mixed materials are put into a twin-screw extruder, extruded and pelletized, and dried to obtain the polypropylene cable material.

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

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

[0030] The intramolecular synergistic antioxidant prepared by the present invention has a hindered phenol group and a thioether group, and combines the advantages of the hindered phenol antioxidant and the sulfur antioxidant. The two act synergistically to jointly improve the antioxidant capacity of the material. At the same time, the intramolecular synergistic antioxidant has a symmetrical molecular structure and low polarity, and will not deteriorate the insulating properties of the material. Moreover, compared with the commonly used hindered phenol antioxidant and the sulfur antioxidant, the intramolecular synergistic antioxidant prepared by the present invention can significantly increase the oxidation induction period and volume resistivity of the material under the same addition amount, and the intramolecular synergistic antioxidant prepared by the present invention has a better effect.

[0031] The present invention uses the above-prepared intramolecular synergistic antioxidant to prepare a polypropylene cable material. In the present invention, homopolypropylene, copolymer polypropylene, ethylene-octene copolymer, ultraviolet light absorber, light stabilizer and intramolecular synergistic antioxidant are used as components of the polypropylene cable material, and each component cooperates with each other. Homopolypropylene is used to maintain the overall strength and melting point of the material, copolymer polypropylene is used to improve the impact resistance of the material, ethylene-octene copolymer is used to improve the toughness of the material and maintain the volume resistivity, and ultraviolet light absorber and light stabilizer are used to improve the resistance to ultraviolet light. The addition of the intramolecular synergistic antioxidant can significantly improve the material's resistance to high temperature thermal aging, will not significantly reduce the material's insulation performance, and does not require a very high addition amount to obtain a polypropylene cable material with excellent performance.

[0032] The cable material prepared by the invention has excellent mechanical properties and high temperature heat aging resistance, and also maintains the insulation performance of the polypropylene cable material, and the preparation process is simple, and has great application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is the infrared spectrum of intramolecular synergistic antioxidant-1;

[0034] Figure 2 This is the reaction process diagram of intramolecular synergistic antioxidant-1;

[0035] Figure 3 This is the reaction process diagram of intramolecular synergistic antioxidant-8;

[0036] Figure 4 This is the reaction process diagram of intramolecular synergistic antioxidant-9. DETAILED DESCRIPTION

[0037] In order to better illustrate the purpose, technical scheme and advantages of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. Its purpose is to understand the content of the present invention in detail, rather than to limit the present invention. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Unless otherwise specified, the experimental reagents and instruments designed for the implementation and comparative examples of the present invention are all commonly used ordinary reagents and instruments, which can be obtained from commercial channels. In the implementation and comparative examples, the experimental methods used are conventional methods unless otherwise specified; and unless otherwise specified, the raw materials used in parallel experiments are the same batch of raw materials.

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

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

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

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

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

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

[0044] Ultraviolet light absorber: UV329, commercially available;

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

[0046] Intramolecular synergistic antioxidant-1: Homemade, the preparation method is as follows: first dissolve 0.01 mol of 2,6-di-tert-butyl-4-vinylphenol in 23.2 g of tetrahydrofuran; at the same time, mix 0.005 mol of ethylene glycol bis(thioglycolate), 0.05 g of triethylamine, and 10.5 g of tetrahydrofuran evenly, and react the two in a nitrogen atmosphere at 60°C. After 8 hours of reaction time, the reaction solution is 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: Homemade, the preparation method is as follows: Different from intramolecular synergistic antioxidant-1, 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; at the same time, 0.005 mol of ethylene glycol bis(thioglycolate), 0.05 g of triethylamine, and 10.5 g of N,N'-dimethylformamide were evenly mixed, and the two were reacted in a nitrogen atmosphere at 60°C. After a certain reaction time of 8 hours, the reaction solution was distilled under reduced pressure, washed with water, and dried to obtain an intramolecular synergistic antioxidant-2 with a yield of 73.2%.

[0049] Intramolecular synergistic antioxidant-3: Homemade, the preparation method is as follows: Different from intramolecular synergistic antioxidant-1, the reaction time is changed.

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

[0051] Intramolecular synergistic antioxidant-4: Homemade, the preparation method is as follows: Different from 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; at the same time, 0.005 mol of ethylene glycol bis(thioglycolate), 0.05 g of triethylamine, and 10.5 g of tetrahydrofuran were evenly mixed, and the two were reacted in a nitrogen atmosphere at 60°C. After 12 hours of reaction time, the reaction solution was distilled under reduced pressure, washed with water, and dried to obtain an intramolecular synergistic antioxidant-4 with a yield of 76.2%.

[0053] Intramolecular synergistic antioxidant-5: Homemade, the preparation method is as follows: Different from 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; at the same time, 0.005 mol of ethylene glycol bis(thioglycolate), 0.05 g of triethylamine, and 10.5 g of tetrahydrofuran were evenly mixed, and the two were reacted in a nitrogen atmosphere at 40°C. After 8 hours of reaction time, the reaction solution was distilled under reduced pressure, washed with water, and dried to obtain an intramolecular synergistic antioxidant-5 with a yield of 55.7%.

[0055] Intramolecular synergistic antioxidant-6: Homemade, the preparation method is as follows: Different from 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; at the same time, 0.005 mol of ethylene glycol bis(thioglycolate), 0.05 g of triethylamine, and 10.5 g of tetrahydrofuran were evenly mixed, and the two were reacted in a nitrogen atmosphere at 80°C. After 8 hours of reaction time, 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: Homemade, the preparation method is as follows: Different from 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; at the same time, 0.005 mol of ethylene glycol bis(thioglycolate), 0.055 g of N,N'-dimethylpyridine and 10.5 g of tetrahydrofuran were evenly mixed, and the two were reacted in a nitrogen atmosphere at 60°C. After a certain reaction time of 8 hours, 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] Preparation of intramolecular synergistic antioxidant-1 to intramolecular synergistic antioxidant-7. The intramolecular synergistic antioxidants finally prepared are exactly the same, only the preparation yields are different. The infrared spectra of intramolecular synergistic antioxidant-1 to intramolecular synergistic antioxidant-7 are as follows Figure 1 As shown, we can see that the wave number is 3591.1cm -1 It is the stretching vibration peak of the free phenolic hydroxyl group on the benzene ring, 2954.2cm -1 and 2914.1cm -1 Nearby are the symmetric and antisymmetric stretching vibration peaks of methylene and methyl, 1734.1cm -1 The characteristic peak of carbonyl stretching vibration is 1434.7 cm -1 It is the characteristic peak of skeleton vibration in benzene ring. 1378.6cm -1 is the stretching vibration peak of the methyl group on the tert-butyl group, 1147.0 cm -1 is the stretching vibration peak of COC, 768.5cm -1 and 873.9cm -1 It is the characteristic peak of benzene ring tetrasubstituted, 642.9cm -1 It is the characteristic stretching peak of CSC in thioether.

[0060] Intramolecular synergistic antioxidant-8: Homemade, the preparation method is as follows: first dissolve 0.01 mol of 2,6-di-tert-butyl-4-allyl phenol in 24.6 g of tetrahydrofuran; at the same time, evenly mix 0.005 mol of ethylene glycol bis(thioglycolate), 0.05 g of triethylamine, and 10.5 g of tetrahydrofuran, and react the two in a nitrogen atmosphere at 60°C. After 8 hours of reaction time, the reaction solution is distilled under reduced pressure, washed with water, and dried to obtain intramolecular synergistic antioxidant-8.

[0061] Intramolecular synergistic antioxidant-9: Homemade, the preparation method is as follows: first dissolve 0.01 mol of 2-tert-butyl-6-(2-hydroxy-3-tert-butyl-5-methylphenyl)methyl-4-methylphenyl acrylate in 39.4 g of tetrahydrofuran; at the same time, evenly mix 0.005 mol of ethylene glycol bis(thioglycolate), 0.05 g of triethylamine, and 10.5 g of tetrahydrofuran, and react the two in a nitrogen atmosphere at 60°C. After 8 hours of reaction time, the reaction solution is distilled under reduced pressure, washed with water, and dried to obtain intramolecular synergistic antioxidant-9.

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

[0063] Examples and Comparative Examples

[0064] Example 1

[0065] A polypropylene cable material comprises the following components in parts by weight: 34 parts of homopolypropylene-1, 34 parts of copolymer polypropylene-1, 30 parts of ethylene-octene copolymer POE8150, 0.5 parts of ultraviolet light absorber UV329, 0.5 parts of light stabilizer UV 770, and 0.5 parts of intramolecular synergistic antioxidant-1.

[0066] The present invention provides a polypropylene cable material. The preparation method of the polypropylene cable material comprises the following steps:

[0067] S1: Put all the above raw materials into a mixer and mix them evenly;

[0068] S2: putting the uniformly mixed materials into a twin-screw extruder, extruding and pelletizing, and drying to obtain the polypropylene cable material; the set temperatures of the twin-screw extruder are: zone 1: 140°C, zone 2: 175°C, zone 3: 215°C, zone 4: 220°C, zone 5: 220°C, zone 6: 220°C, zone 7: 215°C, zone 8: 215°C, zone 9: 220°C, zone 10: 220°C, and the screw speed is 350r / min.

[0069] Example 2

[0070] A polypropylene cable material, the only difference from Example 1 is that homopolymer polypropylene-2 ​​is used, and 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 that copolymerized polypropylene-2 ​​is used, and 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 that an intramolecular synergistic antioxidant-8 is used, and 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 that an intramolecular synergistic antioxidant-9 is used, and 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, and 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, and 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, and the components, weight parts and preparation method are exactly the same.

[0083] Comparative Example 4

[0084] A polypropylene cable material, the only difference from Example 1 is that the intramolecular synergistic antioxidant-1 is replaced by antioxidant 1076, and 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 the intramolecular synergistic antioxidant-1 is replaced by antioxidant 1010, and 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 after heat aging at 150℃ / 168h: T / SHPTA 014.1-2021;

[0091] 4. Change of elongation at break after thermal 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] It can be seen from the above table that the polypropylene cable material prepared by the embodiment has excellent mechanical properties, and the tensile strength and elongation at break are much higher than the relevant provisions in the standard T / SHPTA 014.1-2021, and the high temperature thermal aging resistance is significantly increased, which is much higher than the standard T / SHPTA 014.1-2021. The air thermal aging test evaluation conditions specified in the standard T / SHPTA 014.1-2021. After aging at 150°C / 168h, the retention values ​​of strength and elongation at break should not be less than 25% of the original value. The performance is very excellent, indicating that the polypropylene cable material prepared by the present invention has strong resistance to high temperature thermal aging. In addition, the oxidation induction period of the polypropylene cable material prepared by the embodiment is greatly improved compared with that of comparative examples 1-5, indicating that the polypropylene cable material prepared by the present invention has strong resistance to thermal oxidation. The polypropylene cable material prepared in the embodiment also retains a relatively high volume resistivity. At 10 17 The volume resistivity at 20℃ is higher than 10 in standard T / SHPTA 014.1-2021. 16 The performance is very excellent, which shows that the polypropylene cable material prepared by the present invention maintains high insulation performance.

[0097] By comparing Example 1 and Example 4, the change rate of tensile strength and the change rate of elongation 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 the hydroperoxide produced by aging and be oxidized to a sulfoxide group or a sulfonyl group. Both groups are electron-withdrawing substituents, which greatly reduce the activity of hindered phenol. In Example 1, the distance between the sulfur atom and the hindered phenol in the intramolecular synergistic antioxidant 1 is relatively close, so the activity of hindered phenol will be reduced to a certain extent. By comparing Example 4 and Example 5, the change rate of tensile strength and the change rate of elongation after aging in Example 4 are slightly higher than those in Example 5. This is also because the distance between the sulfur atom and the hindered phenol in the intramolecular synergistic antioxidant 9 in Example 5 is larger than that in the intramolecular synergistic antioxidant 8, so the effect on the activity of hindered phenol is lower, and the steric hindrance at the sulfur atom is relatively small, so it is easier to react with the hydroperoxide to form a stable compound, so the heat aging resistance is better.

[0098] In summary, the cable material prepared by the present invention has excellent mechanical properties and high temperature heat aging resistance. While improving toughness and heat oxidation aging resistance, it also maintains the insulation performance of polypropylene cable material, and the preparation process is simple, which has great application prospects.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. An intramolecular synergistic antioxidant, characterized in that: 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); 2. A method for preparing the intramolecular synergistic antioxidant as claimed in claim 1, characterized in that: The steps include: S1, dissolving the hindered phenol olefin compound in an organic solvent to obtain a mixed solution A; S2, mixing ethylene glycol bis(thioglycolate), a tertiary amine catalyst and an organic solvent uniformly, and reacting to obtain a mixed solution B; S3, mixing the mixed solution A and the mixed solution B evenly, and obtaining the intramolecular synergistic antioxidant after reaction.

3. The method for preparing the intramolecular synergistic antioxidant according to claim 2, characterized in that: In the S1, the mass ratio of hindered phenol olefin compound and organic solvent is hindered phenol olefin compound: organic solvent = 1: (5-10); in the S2, the molar ratio of ethylene glycol bisthioglycolate and tertiary amine catalyst is ethylene glycol bisthioglycolate: tertiary amine catalyst = 100: (1-5), and the mass ratio of ethylene glycol bisthioglycolate and organic solvent is ethylene glycol bisthioglycolate: organic solvent = 1: (5-10).

4. The method for preparing the intramolecular synergistic antioxidant according to claim 2, characterized in that: The hindered phenol 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.

5. Use of the intramolecular synergistic antioxidant as claimed in claim 1 in the preparation of polypropylene cable materials.

6. A polypropylene cable material, characterized in that: The invention comprises the following components in parts by weight: 25-45 parts of homopolypropylene, 25-45 parts of copolymer polypropylene, 25-45 parts of ethylene-octene copolymer, 0.1-1 parts of ultraviolet light absorber, 0.1-1 parts of light stabilizer and 0.1-1 parts of the intramolecular synergistic antioxidant according to claim 1.

7. The polypropylene cable material according to claim 6, characterized in that: The melt flow rate of the homopolypropylene is ≤3.5 g / 10 min, and the test condition is 230° C. / 2.16 kg; the melt flow rate of the copolymer polypropylene is ≤2.5 g / 10 min, and the test condition is 230° C. / 2.16 kg; the mass fraction of α-olefin in the ethylene-octene copolymer is 20%-35%.

8. A method for preparing a polypropylene cable material as claimed in claim 6 or 7, characterized in that: The following steps are involved: (1) Put all the above raw materials into a mixer and mix them evenly; (2) The uniformly mixed materials are put into a twin-screw extruder, extruded and pelletized, and dried to obtain the polypropylene cable material.

Images