Polypropylene insulating material for anti-interference and anti-attenuation cable and preparation process thereof

Abstract

This invention relates to the field of polypropylene insulation material preparation technology, and discloses an anti-interference and anti-attenuation polypropylene insulation material for cables and its preparation process. Specifically, the process involves: preparing a vinylsiloxane hindered phenolic anti-aging monomer; based on the atom transfer radical polymerization mechanism, using the vinylsiloxane hindered phenolic anti-aging monomer as the polymerizing monomer, using the bromine functional groups on the surface of brominated nano-magnesium oxide as the initiator, and cuprous halide as the catalyst, to obtain modified nano-magnesium oxide with surface polymerized siloxane chains and hindered phenolic structures; using polypropylene as raw material, modified nano-magnesium oxide as filler, and lubricant and flame retardant as additives, and then processing through extrusion granulation, drying, and injection molding to obtain the polypropylene insulation material. This invention significantly improves the mechanical properties and thermo-oxidative aging resistance of polypropylene insulation materials by using modified nano-magnesium oxide with surface polymerized siloxane chains and hindered phenolic structures as a functional filler for polypropylene.

Description

Technical Field

[0001] This invention relates to the field of polypropylene insulation material preparation technology, specifically to an anti-interference and anti-attenuation type polypropylene insulation material for cables and its preparation process. Background Technology

[0002] Cables generally consist of a conductor, an insulation layer, and a shielding layer. The shielding layer primarily serves to resist interference (such as electromagnetic interference and radio frequency interference), while the insulation layer protects the conductor from damage caused by wear, oxidation, or other environmental factors. Insulation materials include plastic and rubber materials. Among many insulation materials, polypropylene (PP) has become an ideal cable insulation material due to its excellent electrical insulation properties, low dielectric loss, strong anti-attenuation ability, high volume resistivity, and low cost.

[0003] However, ordinary PP has problems with poor low-temperature toughness and low impact resistance. In cold environments, the insulation layer of PP cables may break due to mechanical impact or bending, leading to cable damage and power transmission interruption. In addition, the insulation temperature of the cable can reach up to 90°C during normal operation, but when the cable is overloaded or short-circuited, the insulation temperature can reach 150°C in a short time. There are a large number of low-energy tertiary hydrogen bonds in the PP molecular chain structure, which are easy to break at high temperatures and transform into active tertiary carbon free radicals. Tertiary carbon free radicals will undergo aging and degradation phenomena such as chain growth and chain breakage in the presence of oxygen, resulting in irreversible damage to the physicochemical structure and insulation properties of the material, affecting the reliability and service life of the cable system.

[0004] Currently, small-molecule antioxidants are often added to inhibit the thermo-oxidative aging of PP. However, small-molecule antioxidants have problems such as easy volatility and migration, resulting in insufficient resistance to thermo-oxidative aging and a significant reduction in the service life of cables. The main means to improve the low-temperature toughness of PP is to add rubber or polyolefin elastomers to PP for blending, but the insulation performance of the material will decrease. By introducing nanoscale fillers such as magnesium oxide, silicon dioxide, and aluminum oxide into the polypropylene matrix, its electrical, thermal, and mechanical properties can be improved. At the same time, the introduction of nanofillers can significantly improve the dielectric properties of the material. However, the interfacial compatibility between nanofillers and PP is poor, and agglomeration is prone to occur. Summary of the Invention

[0005] The purpose of this invention is to provide an anti-interference and anti-attenuation type polypropylene insulation material for cables and its preparation process, which solves the following technical problems: (1) It solves the problem of poor low-temperature toughness of polypropylene insulation material.

[0006] (2) The problem of poor resistance to thermo-oxidative aging of polypropylene insulation material has been solved.

[0007] The objective of this invention can be achieved through the following technical solution: a preparation process for an anti-interference and anti-attenuation type polypropylene insulation material for cables, comprising the following steps: Step 1: preparing vinylsiloxane hindered phenolic anti-aging monomer.

[0008] Step 2: Based on the atom transfer radical polymerization mechanism, using the vinylsiloxane hindered phenolic anti-aging monomer as the polymerization monomer, the bromine functional groups on the surface of brominated nano-magnesium oxide as the initiator, and cuprous halide as the catalyst, modified nano-magnesium oxide with siloxane chains and hindered phenolic structures on its surface was prepared.

[0009] Step 3: Using polypropylene as raw material, modified nano-magnesium oxide as filler, and lubricant and flame retardant as additives, polypropylene insulation material is obtained through extrusion granulation, drying and injection molding processes.

[0010] Preferably, the method for preparing the vinylsiloxane hindered phenolic anti-aging monomer is as follows: a condensation reaction is carried out between the silanol functional group in the 1,5-dichlorohexamethyltrisiloxane structure and the silanol functional group in the vinyldimethylethoxysilane structure at a molar ratio of 1:(2-2.01) to obtain the divinylpentasiloxane monomer.

[0011] In the presence of a photoinitiator, a carboxylated pentasiloxane monomer is prepared by a click reaction between the mercapto functional group of 1 molar equivalent of 3-mercaptopropionic acid and the alkenyl functional group of (1-1.02) molar equivalents of divinylpentasiloxane under ultraviolet light.

[0012] Under the action of an acid catalyst, the carboxyl group of the carboxylated pentasiloxane monomer undergoes an esterification reaction with the hydroxyl group of 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, and the molar ratio of the carboxylated pentasiloxane monomer to 3,5-di-tert-butyl-4-hydroxybenzyl alcohol is controlled to be 1:(1-1.02) to obtain a vinylsiloxane hindered phenolic anti-aging monomer.

[0013] Preferably, the photoinitiator is one of benzoin dimethyl ether, benzoin isopropyl ether, and benzoin ethyl ether.

[0014] Preferably, the acid catalyst is one of p-toluenesulfonic acid and trifluoromethanesulfonic acid.

[0015] Preferably, the cuprous halide is one of cuprous bromide, cuprous chloride, and cuprous iodide.

[0016] Preferably, the preparation method of the brominated nano-magnesium oxide is as follows: surface modification of nano-magnesium oxide is performed using 3-aminopropyltriethoxysilane to obtain amino-functionalized nano-magnesium oxide.

[0017] Brominated nano-magnesium oxide was prepared by reacting the amino groups in amino-functionalized nano-magnesium oxide with the acyl bromide groups in 2-bromoisobutyryl bromide.

[0018] Preferably, the particle size of the nano-magnesium oxide is 1-100 nm.

[0019] Preferably, the lubricant is one of calcium stearate or zinc stearate.

[0020] Preferably, the injection molding temperature is 200-220℃ and the pressure is 60-100 MPa.

[0021] Preferably, the polypropylene insulating material comprises the following raw materials in parts by weight: polypropylene resin, 60-100 parts by weight.

[0022] Modified nano-magnesium oxide, 1-10 parts by weight.

[0023] Lubricant, 0.5-1.5 parts by weight.

[0024] Flame retardant, 3-6 parts by weight.

[0025] The present invention has at least one of the following technical effects: 1. The present invention uses modified nano-magnesium oxide with surface polymerized siloxane chains and hindered phenolic structures as a functional filler for polypropylene, which significantly improves the mechanical properties and thermo-oxidative aging resistance of polypropylene insulation materials, and solves the problem of poor toughness at low temperature and poor anti-aging performance at high temperature of polypropylene insulation materials.

[0026] 2. This invention, based on molecular design and surface functionalization strategies, designs and synthesizes a vinylsiloxane hindered phenolic anti-aging monomer, and grafts it onto the surface of nano-magnesium oxide via atom transfer radical polymerization to construct a highly dispersed and highly stable modified nano-magnesium oxide. This modification strategy achieves multiple synergistic functions: through surface organic modification, the interfacial compatibility of nano-magnesium oxide in a non-polar polypropylene matrix is ​​significantly improved, enabling it to be uniformly dispersed in polypropylene insulating materials and effectively avoiding the aggregation problem of inorganic nanoparticles; by anchoring the hindered phenolic structure to the surface of nano-magnesium oxide through covalent bonds, the problem of easy volatility, easy migration, and poor durability of traditional small molecule anti-aging agents is fundamentally solved. The bottleneck issues such as poor extractability are addressed by providing the material with stable anti-aging capabilities. Nano-magnesium oxide, as a rigid inorganic filler, plays a reinforcing role in the polypropylene matrix. At the same time, the flexible siloxane segments grafted on its surface can toughen the material at the molecular level, synergistically improving the tensile strength and elongation at break of the material, effectively reducing the low-temperature brittleness of the polypropylene molecular chain, and significantly improving the low-temperature toughness of the material. Meanwhile, the synergistic effect of inorganic nanoparticles and hindered phenolic structures enhances the thermal stability of the material and broadens its operating temperature range. By utilizing the free radical scavenging ability of the hindered phenolic structure and the thermal stabilizing effect of nano-magnesium oxide, the anti-aging performance and mechanical properties of polypropylene insulation materials are improved simultaneously. Detailed Implementation

[0027] The present invention will now be described in detail through specific embodiments. However, these illustrative embodiments are for purposes and uses only to illustrate the invention and do not constitute any limitation on the actual scope of protection of the invention, nor are they intended to limit the scope of protection of the invention to these embodiments. All equivalent transformations or simple substitutions made based on the substantive content of this application should fall within the scope of protection of this application. For parameter ranges not mentioned, intermediate values ​​are selected. Furthermore, for mass percentages or weight percentages not explicitly stated or mentioned, they generally refer to the final concentration after addition.

[0028] The singular forms “for,” “or,” “a,” “any,” and “the” used in this application are intended to include the plural forms unless the context clearly indicates otherwise.

[0029] Example 1:

[0030] I. Preparation of Vinylsiloxane Hindered Phenolic Anti-Aging Monomer, comprising the following steps: Step S1: Preparation of divinylpentasiloxane monomer, the preparation mechanism of which is: by hydrolyzing the silanol functional group (Si-Cl) in the structure of 1,5-dichlorohexamethyltrisiloxane with the silanol functional group in the structure of vinyldimethylethoxysilane to generate the corresponding silanol intermediate, the two are then dehydrated and condensed to form Si-O-Si bonds to obtain divinylpentasiloxane monomer, the specific steps of which are as follows: 4.16g of 1,5-dichlorohexamethyltrisiloxane is added to... Mixed solution one was prepared by mechanically stirring a mixture of 30 mL anhydrous tetrahydrofuran and 20 mL deionized water for 25 min. 3.91 g of vinyldimethylethoxysilane was then added to the mixture and stirred until homogeneous to obtain mixed solution two. Mixed solution two and 1.5 mL of glacial acetic acid were added to mixed solution one, and the mixture was stirred at 60 °C for 8 h. After the reaction was complete, the mixture was cooled to room temperature, the solvent was removed by rotary evaporation, and the mixture was vacuum dried at 40 °C for 5 h to obtain divinylpentasiloxane monomer.

[0031] The chemical structural formula of the divinylpentasiloxane monomer is: .

[0032] The 1H NMR spectrum of the divinylpentasiloxane monomer is characterized as follows: 1 H NMR (CDCl3, 400MHz) δ: 0.01 (s, 12H), 0.09 (s, 18H), 5.72-5.84 (dd, 4H), 6.01-6.07 (t, 2H).

[0033] Step S2: Preparation of carboxylated pentasiloxane monomer. The preparation mechanism is as follows: In the presence of benzoin dimethyl ether photoinitiator, the alkenyl functional group in the divinylpentasiloxane molecule undergoes a photochemical reaction under ultraviolet light irradiation. The thiol functional group of 3-mercaptopropionic acid selectively undergoes a thiol-alkene click reaction with one of the vinyl groups, forming a thioether bond through free radical addition, thereby introducing the carboxyl group into the siloxane skeleton to obtain the carboxylated pentasiloxane monomer. The specific steps are as follows: 6.13g of divinylpentasiloxane monomer, 1.59g of 3-mercaptopropionic acid, 0.02g of benzoin dimethyl ether photoinitiator, and 60mL of tetrahydrofuran are added to a 250mL three-necked flask. The mixture is mechanically stirred until homogeneous, and the system is placed under an ultraviolet lamp for 1h. After the reaction is completed, the solvent is removed by rotary evaporation, and the mixture is dried in a vacuum drying oven at 40℃ to constant weight to obtain the carboxylated pentasiloxane monomer.

[0034] The chemical structural formula of the carboxylated pentasiloxane monomer is: .

[0035] The proton NMR spectrum of the carboxylated pentasiloxane monomer is characterized as follows: 1¹H NMR (CDCl₃, 400MHz) δ: 0.03 (s, 6H), 0.05 (s, 6H), 0.08 (s, 6H), 0.11 (s, 12H), 0.94–0.98 (t, 2H), 2.44–2.47 (t, 2H), 2.55–2.57 (t, 2H), 2.77–2.79 (t, 2H), 5.69–5.78 (dd, 2H), 5.97–6.02 (t, 1H); The active hydrogen in the carboxyl functional group of the carboxylated pentasiloxane monomer did not elute in CDCl₃ solvent.

[0036] Step S3: Preparation of vinylsiloxane hindered phenolic anti-aging monomer. The preparation mechanism is as follows: Under the catalysis of p-toluenesulfonic acid, the carboxyl group in the structure of the carboxylated pentasiloxane monomer undergoes an esterification reaction with the hydroxyl group in the structure of 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, resulting in dehydration and the formation of ester bonds, thus obtaining the vinylsiloxane hindered phenolic anti-aging monomer. The specific steps are as follows: 5.14 g of carboxylated pentasiloxane monomer and 2.37 g of 3,5-di-tert-butyl-4-hydroxybenzyl alcohol are added to 60 mL of toluene and mechanically stirred until homogeneous. 0.1 g of p-toluenesulfonic acid is added and mixed well. Three boiling chips are added, and the reaction is carried out at a reflux temperature of 90 °C for 4 h until the water volume in the separator no longer increases. After the reaction is completed, toluene is removed by rotary evaporation, and the product is vacuum dried at 60 °C for 8 h to obtain the vinylsiloxane hindered phenolic anti-aging monomer.

[0037] The chemical structural formula of the vinylsiloxane hindered phenolic anti-aging monomer is as follows: .

[0038] The 1H NMR characterization of the vinylsiloxane hindered phenolic anti-aging monomer is as follows: 1 H NMR (DMSO-d6, 400MHz) δ: 0.02 (s, 6H), 0.03 (s, 6H), 0.07 (s, 6H), 0.10 (s, 12H), 0.97-1.00 (t, 2H), 1.41 (s, 18H), 2.48-2.51 (t, 2H), 2.59-2.62 (t, 2H), 2.79-2.82 (t, 2H), 5.13-5.14 (t, 2H), 5.68 (s, 1H), 5.76-5.84 (dd, 2H), 6.01-6.07 (t, 1H), 7.13 (s, 2H).

[0039] II. Preparation of modified nano-magnesium oxide, including the following steps: Step SS1: Preparation of amino-functionalized nano-magnesium oxide. The preparation mechanism is as follows: Nano-magnesium oxide is treated with 3-aminopropyltriethoxysilane. The triethoxy functional group in 3-aminopropyltriethoxysilane undergoes a hydrolysis reaction in a mixed solvent of deionized water and anhydrous ethanol. The resulting Si-OH functional group readily forms hydrogen bonds with oxygen on the surface of nano-magnesium oxide, thereby tightly adsorbing 3-aminopropyltriethoxysilane onto the surface of nano-magnesium oxide. The specific steps for preparing amino-functionalized nano-magnesium oxide are as follows: 5g of nano-magnesium oxide (particle size of 50nm), 1g of 3-aminopropyltriethoxysilane, 10mL of deionized water and 50mL of anhydrous ethanol were added to a 250mL three-necked flask. The mixture was ultrasonically dispersed for 30min. Then, the three-necked flask was transferred to a water bath, the temperature was raised to 80℃, and the mixture was stirred for 60min. The mixture was then filtered, washed three times with anhydrous ethanol, and vacuum dried at 60℃ for 5h to obtain amino-functionalized nano-magnesium oxide.

[0040] Step SS2: Preparation of brominated nano-magnesium oxide. The preparation mechanism is as follows: Based on the amino-acylbromine amidation reaction mechanism, the amino groups on the surface of amino-functionalized nano-magnesium oxide act as nucleophiles to attack the carbonyl carbon atom in the acylbromine group of 2-bromoisobutyryl bromide, first forming a tetrahedral intermediate, then the bromide ion leaves as a leaving group, finally generating an amide bond, so that 2-bromoisobutyryl bromide is covalently grafted to the surface of nano-magnesium oxide through the amide bond, thus obtaining brominated nano-magnesium oxide. The specific steps are as follows: 5 0.5 g of amino-functionalized nano-magnesium oxide and 0.5 g of triethylamine were added to 50 mL of anhydrous dichloromethane and mechanically stirred until homogeneous. The mixture was cooled to 0 °C, and 0.9 g of 2-bromoisobutyryl bromide was added dropwise. The mixture was stirred at 0 °C for 30 min, and then stirred at room temperature for 12 h. After the reaction was completed, the mixture was centrifuged (12000 r / min, 5 min) to separate the components. After removing the supernatant, the mixture was washed three times with ethanol and deionized water, and then vacuum dried at 60 °C for 12 h to obtain brominated nano-magnesium oxide.

[0041] Step SS3: Preparation of modified nano-magnesium oxide. The preparation mechanism is as follows: Based on the atom transfer radical polymerization mechanism, the hindered phenolic anti-aging monomer of vinylsiloxane is used as the polymerization monomer, the bromine functional groups on the surface of brominated nano-magnesium oxide are used as the initiator, cuprous bromide is used as the catalyst, and N,N,N',N'',N''-pentamethyldiethylenetriamine is used as the ligand. The bromine functional groups (dormant species) on the surface of nano-magnesium oxide undergo a single-electron redox reaction with the catalyst cuprous bromide [Cu(I)], and the C-Br bond is homolytically cleaved to generate surface carbon free radicals (active species). At the same time, Cu(I) is oxidized to Cu(II). These surface free radicals rapidly attack the carbon-carbon double bonds of the hindered phenolic monomer of vinylsiloxane to initiate polymerization. The growing surface free radicals then undergo a reversible reaction with Cu(II) in the system, regaining bromine atoms and returning to the dormant state. At the same time, Cu(II) is reduced to Cu(I). This dynamic balance of "activation-deactivation" greatly reduces the concentration of free radicals in the system and effectively inhibits side reactions such as chain termination. Modified nano-magnesium oxide is obtained by continuously inserting and growing monomers on the surface of nano-magnesium oxide. The specific steps are as follows: 1g of brominated nano-magnesium oxide is added to 30mL of N,N-dimethylformamide and ultrasonically dispersed until a uniform dispersion is formed. 0.12g of cuprous bromide and 3g of vinylsiloxane hindered phenolic anti-aging monomer are added to the dispersion and mixed well. 0.15g of N,N,N',N'',N''-pentamethyldiethylenetriamine is added, and the system temperature is raised to 60℃. The reaction is stirred for 24h under nitrogen protection. After the reaction is completed, the solid material is separated by centrifugation (9000r / min, 5min), washed, and dried in a vacuum drying oven at 60℃ to constant weight to obtain modified nano-magnesium oxide.

[0042] III. Preparation of polypropylene insulation material a, the raw material formula is: polypropylene resin (brand name H920Y, density 0.90 g / cm³). 3 ), 80 parts by weight.

[0043] Modified nano-magnesium oxide, 5 parts by weight.

[0044] Calcium stearate lubricant, 1 part by weight.

[0045] Flame retardant FRC-2, 5 parts by weight.

[0046] The preparation method of polypropylene insulation material a includes the following steps: According to the formula of polypropylene insulation material a, the ingredients are prepared by adding polypropylene, modified nano-magnesium oxide, calcium stearate, and flame retardant FRC-2 into a high-speed mixer and mixing them evenly. The mixed material is then placed in a twin-screw extruder for extrusion granulation, wherein the screw speed is 150 r / min, and the temperatures of zones 1-4 are 170℃, 180℃, 190℃, and 200℃, respectively. The granules are then placed in a 105℃ forced-air drying oven for 2 hours to remove moisture, obtaining composite masterbatch. Samples are then prepared using an injection molding machine, wherein the injection molding machine temperature is 210℃ and the pressure is 80 MPa, thus obtaining polypropylene insulation material a.

[0047] Example 2:

[0048] Polypropylene insulating material b is prepared, and its only difference from polypropylene insulating material a is that the amount of modified nano magnesium oxide used is 1 part by weight.

[0049] Example 3:

[0050] The polypropylene insulating material c is prepared, and its only difference from that of polypropylene insulating material a is that the amount of modified nano-magnesium oxide used is 3 parts by weight.

[0051] Example 4:

[0052] The polypropylene insulating material d is prepared, and its only difference from that of polypropylene insulating material a is that the amount of modified nano-magnesium oxide used is 8 parts by weight.

[0053] Example 5:

[0054] The polypropylene insulating material e is prepared, and its only difference from that of polypropylene insulating material a is that the amount of modified nano-magnesium oxide used is 10 parts by weight.

[0055] Example 6:

[0056] The polypropylene insulating material f is prepared, and its only difference from that of polypropylene insulating material a is that the lubricant is magnesium stearate.

[0057] Comparative Example 1:

[0058] Polypropylene insulating material g is prepared, and its only difference from polypropylene insulating material a is that modified nano-magnesium oxide is replaced with nano-magnesium oxide.

[0059] Comparative Example 2:

[0060] Polypropylene insulation material i is prepared, and its only difference from polypropylene insulation material a is that the modified nano-magnesium oxide is replaced with vinylsiloxane hindered phenolic anti-aging monomer.

[0061] Comparative Example 3:

[0062] The polypropylene insulation material h is prepared in a manner that differs from polypropylene insulation material a only in that it does not contain modified nano-magnesium oxide.

[0063] Performance testing:

[0064] (1) The tensile strength and elongation at break of the polypropylene insulation materials prepared in the embodiments and comparative examples of the present invention were tested using a universal electronic testing machine in accordance with GB / T 2951.11-2008 General Test Methods for Insulation and Sheath Materials of Cables and Optical Cables Part 11: General Test Methods for Thickness and Dimensional Measurement and Mechanical Properties Test. The tests were conducted at room temperature.

[0065] (2) The polypropylene insulation materials prepared in the embodiments and comparative examples of the present invention were subjected to aging treatment according to GB / T 2951.12-2008 "General test methods for insulation and sheath materials of cables and optical cables - Part 12: General test methods - thermal aging test method". The air oven aging treatment method was used, the aging temperature was 135℃ and the aging time was 168h. The tensile strength of the polypropylene insulation materials was tested again.

[0066] (3) The polypropylene insulation materials prepared in the embodiments and comparative examples of the present invention were subjected to a low-temperature winding test according to GB / T 2951.14-2008 General Test Methods for Insulation and Sheath Materials of Cables and Optical Cables Part 14: General Test Methods for Low Temperature Test. The temperature was -15℃ and the time was 24h. The samples were observed to see if cracks appeared.

[0067] The test results are shown in Table 1 below:

[0068] Table 1 Performance test results of polypropylene insulation materials

[0069]

[0070] The experimental results above show that, by simply changing the amount of modified nano-magnesium oxide added, the tensile strength of the polypropylene insulation material at room temperature increases (35.6 MPa → 48.0 MPa) and the elongation at break increases (589.13 → 682.51) as the content of modified nano-magnesium oxide increases. After aging, the tensile strength of the polypropylene insulation material only decreases slightly (0.3-2.1 MPa), indicating excellent anti-aging performance. No cracks appeared in the polypropylene insulation material at low temperature, and the low-temperature toughness is good.

[0071] A comparison of Example 1 and Comparative Example 1 shows that by adding modified nano-magnesium oxide, the tensile strength of polypropylene insulation material at room temperature is enhanced (22.8 MPa → 45.2 MPa), the elongation at break increases (409.52 → 654.18), the tensile strength of polypropylene insulation material decreases only slightly after aging, and the polypropylene insulation material at low temperature is improved from having obvious cracks to having no cracks, which can significantly improve the anti-aging performance and low-temperature toughness of polypropylene insulation material.

[0072] As can be seen from the comparison between Example 1 and Comparative Example 1, by organically modifying nano-magnesium oxide, the tensile strength of polypropylene insulation material at room temperature is enhanced (26.1MPa→45.2MPa), and the elongation at break is increased (378.49→654.18). The tensile strength of polypropylene insulation material decreases by 0.7MPa after aging, which is a small decrease. In low-temperature environments, the appearance of obvious cracks is improved to no cracks, which significantly improves the anti-aging performance and low-temperature toughness of polypropylene insulation material.

[0073] A comparison of Example 1 and Comparative Example 2 shows that when vinylsiloxane hindered phenolic anti-aging monomers are coated onto the surface of nano-magnesium oxide via atom transfer radical polymerization, the tensile strength of polypropylene insulation material at room temperature increases (27.5 MPa → 45.2 MPa), and the elongation at break increases (565.31 → 654.18). The decrease in tensile strength of polypropylene insulation material after aging is relatively small, and at low temperatures, the polypropylene insulation material improves from slight cracks to no cracks at all. This indicates that grafting anti-aging monomers onto nano-carriers avoids the disadvantages of small molecules being free and volatile, and improves the toughening effect and anti-aging performance of the material.

[0074] The above results demonstrate and describe the basic principles and main features of this application, as well as its advantages.

[0075] Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this application. Various changes and modifications can be made to this application without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of this application as claimed. The scope of protection of this application is defined by the equivalents of the appended claims.

Claims

1. A preparation process for an anti-interference and anti-attenuation polypropylene insulation material for cables, characterized in that, Includes the following steps: Step 1: Prepare a vinylsiloxane hindered phenolic anti-aging monomer. The chemical structural formula of this anti-aging monomer is as follows: ； Step 2: Based on the atom transfer radical polymerization mechanism, using vinylsiloxane hindered phenolic anti-aging monomer as the polymerization monomer, bromine functional groups on the surface of brominated nano-magnesium oxide as the initiator, and cuprous halide as the catalyst, modified nano-magnesium oxide with siloxane chains and hindered phenolic structures on the surface was prepared. Step 3: Using polypropylene as raw material, modified nano-magnesium oxide as filler, and lubricant and flame retardant as additives, polypropylene insulation material is obtained through extrusion granulation, drying and injection molding processes.

2. The preparation process of the anti-interference and anti-attenuation polypropylene insulation material for cables according to claim 1, characterized in that, The preparation method of the vinylsiloxane hindered phenolic anti-aging monomer is as follows: Divinylpentasiloxane monomer was prepared by condensation reaction of the silanol functional group in the 1,5-dichlorohexamethyltrisiloxane structure with the silanol functional group in the vinyldimethylethoxysilane structure at a molar ratio of 1:(2-2.01). In the presence of a photoinitiator, a carboxylated pentasiloxane monomer was prepared by a click reaction between the mercapto functional group of 1 molar equivalent of 3-mercaptopropionic acid and the alkenyl functional group of (1-1.02) molar equivalent of divinylpentasiloxane under ultraviolet light. Under the action of an acid catalyst, the carboxyl group of the carboxylated pentasiloxane monomer undergoes an esterification reaction with the hydroxyl group of 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, and the molar ratio of the carboxylated pentasiloxane monomer to 3,5-di-tert-butyl-4-hydroxybenzyl alcohol is controlled to be 1:(1-1.02) to obtain a vinylsiloxane hindered phenolic anti-aging monomer.

3. The preparation process of the anti-interference and anti-attenuation polypropylene insulation material for cables according to claim 2, characterized in that, The photoinitiator is one of benzoin dimethyl ether, benzoin isopropyl ether, and benzoin ethyl ether.

4. The preparation process of the anti-interference and anti-attenuation polypropylene insulation material for cables according to claim 2, characterized in that, The acid catalyst is one of p-toluenesulfonic acid and trifluoromethanesulfonic acid.

5. The preparation process of the anti-interference and anti-attenuation polypropylene insulation material for cables according to claim 1, characterized in that, The cuprous halide is one of cuprous bromide, cuprous chloride, and cuprous iodide.

6. The preparation process of the anti-interference and anti-attenuation polypropylene insulation material for cables according to claim 1, characterized in that, The preparation method of the brominated nano-magnesium oxide is as follows: Amino-functionalized magnesium oxide nanoparticles were prepared by surface modification with 3-aminopropyltriethoxysilane. Brominated nano-magnesium oxide was prepared by reacting the amino groups in amino-functionalized nano-magnesium oxide with the acyl bromide groups in 2-bromoisobutyryl bromide.

7. The preparation process of an anti-interference and anti-attenuation type polypropylene insulation material for cables according to claim 6, characterized in that, The particle size of the nano-magnesium oxide is 1-100 nm.

8. The preparation process of the anti-interference and anti-attenuation polypropylene insulation material for cables according to claim 1, characterized in that, The lubricant is one of calcium stearate or zinc stearate.

9. The preparation process of the anti-interference and anti-attenuation polypropylene insulation material for cables according to claim 1, characterized in that, The temperature in the injection molding process is 200-220℃, and the pressure is 60-100Mpa.

10. A polypropylene insulation material for cables with anti-interference and anti-attenuation properties prepared by the process according to any one of claims 1-9, characterized in that, The polypropylene insulation material comprises the following raw materials in parts by weight: Polypropylene resin, 60-100 parts by weight; Modified nano-magnesium oxide, 1-10 parts by weight; Lubricant, 0.5-1.5 parts by weight; Flame retardant, 3-6 parts by weight.

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