Environment-friendly polypropylene cable insulating material and preparation method thereof

Abstract

The invention discloses an environment-friendly polypropylene cable insulating material, which belongs to the technical field of new electrical materials, and is prepared by mixing maleic anhydride grafted polypropylene, maleic anhydride grafted elastomer, polythiol or polyhydric alcohol or an epoxy material and a catalyst, carrying out melting treatment, and carrying out cross-linking reaction to obtain the environment-friendly polypropylene cable insulating material. The environment-friendly polypropylene cable insulating material prepared by the invention has toughness due to the existence of the elastomer, has excellent mechanical properties due to the existence of the cross-linked structure, and retains the recoverable and environment-friendly advantages of polypropylene due to the dynamic nature of the cross-linked structure, so that the environment-friendly polypropylene cable insulating material disclosed by the invention is suitable for practical application and has wide application prospects. Compared with an existing polypropylene cable insulating material, the electrical performance, the mechanical performance and the thermal performance of the polypropylene cable insulating material are greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of new electrical materials, and in particular relates to an environmentally friendly polypropylene cable insulating material and a preparation method thereof. Background Art

[0002] Cross-linked polyethylene (XLPE) is currently the most widely used cable insulation material due to its excellent electrical and mechanical properties. However, XLPE cable insulation consumes a lot of energy during the production process and cannot be recycled after retirement, which is increasingly inconsistent with the needs of low-carbon, environmentally friendly, and high-quality development of the power system. Polypropylene (PP) thermoplastic insulation has received widespread attention at home and abroad due to its low production cost, low production energy consumption, excellent insulation performance, and recyclability after retirement. A large number of studies have shown that polypropylene material is a highly potential alternative to XLPE and is expected to become the mainstream environmentally friendly main insulation material for power cables in the future.

[0003] However, pure PP insulation is difficult to be used directly as cable insulation due to its high hardness and poor toughness. Therefore, it must be modified to meet the requirements of electrical, mechanical and thermal properties of cable insulation materials in practical applications. Reducing the room temperature modulus, improving the mechanical strength at high temperature, and optimizing the electrical performance under a wide temperature range are the three mutually restrictive performance optimization goals currently faced by PP cable insulation, which restricts the practical application of PP-based high-voltage insulation.

[0004] At present, conventional modification methods include blending modification, copolymerization modification and nanoparticle modification. Among them, the most common elastomers for blending modification are ethylene propylene rubber (EPR), ethylene propylene diene monomer rubber (EPDM), polyolefin elastomer (POE), etc., but the blending method can only achieve the optimization of low-temperature toughness. The copolymerization modification method is the copolymerization of propylene with other olefins such as ethylene, butene, and pentene, which can optimize toughness and electrical properties, but the mechanical strength at high temperatures is weak. Nanoparticle modification is to evenly disperse nanoparticles such as MgO and TiO2 in the PP base material, which can form a transition zone with different physical and chemical properties from the matrix and nanoparticles through intermolecular forces or chemical bonds, thereby affecting the performance of the material, but this method has a complex synthesis process and high cost, and the nanoparticles are easy to agglomerate and difficult to disperse evenly. And conventional modification methods have limited effect in improving the mechanical properties of polypropylene cable insulation materials. Summary of the invention

[0005] In order to solve the above technical problems, the present invention proposes an environmentally friendly polypropylene cable insulation material and a preparation method thereof. The environmentally friendly polypropylene cable insulation material prepared by the present invention has toughness due to the presence of the elastomer, has excellent mechanical properties due to the presence of the cross-linked structure, and retains the recyclable environmental protection advantage of polypropylene due to the dynamic nature of the cross-linked structure. The environmentally friendly polypropylene cable insulation material of the present invention is suitable for practical applications, and its electrical properties, mechanical properties and thermal properties are greatly improved compared with existing polypropylene cable insulation materials.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] One of the technical solutions of the present invention:

[0008] The present invention provides an environmentally friendly polypropylene cable insulation material, wherein the environmentally friendly polypropylene cable insulation material has a cross-linked structure represented by formula (I) or formula (II):

[0009]

[0010] In formula (I) and formula (II), X is the part of polythiol of different structures excluding the thiol functional group, or the part of polyol excluding the hydroxyl functional group, or the part of epoxy material excluding the epoxy functional group; the solid line frame is the dynamic crosslinking part, which is connected between the polypropylene segments, between the elastomer segments, or between the polypropylene and the elastomer; the dotted line frame is the specific dynamic crosslinking site.

[0011] The dynamic crosslinking part of the present invention is any dynamic crosslinking structure with a dissociation temperature above 105°C, so as to ensure the structural stability of the polypropylene cable insulation material under normal working conditions and the structural rearrangement at relatively high temperatures. The specific dynamic crosslinking sites in the dotted circle will dissociate at high temperatures (≥105°C).

[0012] Preferably, the raw materials of the environmentally friendly polypropylene cable insulation material include: maleic anhydride grafted polypropylene, maleic anhydride grafted elastomer, and one of polythiol, polyol, and epoxy material.

[0013] Preferably, the grafting rate of the maleic anhydride grafted polypropylene is 0.5-5%.

[0014] Preferably, the grafting rate of the maleic anhydride grafted elastomer is 0.8-2%.

[0015] Preferably, the maleic anhydride grafted elastomer is a product obtained by grafting maleic anhydride onto an elastic material, and the elastic material is an elastic material capable of overcoming the rigidity and brittleness of polypropylene; and / or

[0016] The polythiol is a thiol containing two thiol groups or a thiol containing three or more thiol groups; and / or

[0017] The polyol is an alcohol containing two hydroxyl groups or an alcohol containing three or more hydroxyl groups; and / or

[0018] The epoxy material is a material containing two or more epoxy groups.

[0019] Reducing the room temperature modulus, improving the mechanical strength at high temperature, and optimizing the electrical performance under a wide temperature range are the three performance optimization goals currently faced by polypropylene cable insulation. The most effective way to improve mechanical strength is to establish a cross-linked network, but a permanent cross-linked network similar to that of cross-linked polyethylene cable insulation materials will make the material unrecyclable, so the introduction of a dynamic cross-linked structure is considered. The dynamic cross-linked part maintains a chemical connection at normal operating temperature, and a cross-linked network is established in the polypropylene cable insulation material to improve the mechanical properties of the material. The connection can be disconnected above the dissociation temperature, so that the polypropylene cable insulation material still has recyclable characteristics. The dynamic bond selects the more common dynamic ester bond. A relatively simple way to form a dynamic ester bond is to react a hydroxyl or epoxy group with an anhydride. Maleic anhydride is used as an example in the present invention. If the alkyl oxygen atom in the ester bond is replaced with a sulfur atom of the same family, a dynamic thioester bond can be formed. Since the radius of the sulfur atom is larger, it has a weaker ability to adsorb electrons than oxygen atoms, so the thioester bond is more dynamic than the ester bond. In order to form a dynamic connection between polypropylene segments, there must be two or more functional groups in the cross-linking agent (thiol / alcohol / epoxy) that react with anhydride.

[0020] Preferably, the elastic material includes ethylene propylene rubber (EPR), ethylene propylene diene monomer rubber (EPDM), styrene-butadiene-styrene block copolymer (SBS), polystyrene-polyethylene-polybutylene polystyrene copolymer (SEBS), polyolefin elastomer (POE), ethylene-1-octene block copolymer (OBC) or ethylene-vinyl acetate copolymer (EVA).

[0021] Preferably, the polythiol includes a thiol containing two thiols: 1,4-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, 1,7-heptanedithiol, 1,8-octanedithiol, 1,9-nonanedithiol, 1,10-decanedithiol, 2,6-dimercaptopurine, 1,4-benzenedithiol, 1,4-benzenedimethanethiol, 3,6-dioxa-1,8-octanedithiol, toluene-3,4-dithiol, 4,4'-thiobisbenzenedithiol; or a thiol containing three or more thiol groups: trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionate) or pentaerythritol tetrakis(3-mercaptobutyrate).

[0022] Preferably, the polyol includes an alcohol containing two hydroxyl groups: polyethylene glycol, polypropylene glycol or polybutylene glycol; or an alcohol containing three or more hydroxyl groups: glycerol, trimethylolpropane, sorbitol or fructose alcohol.

[0023] Preferably, the epoxy material is a material containing two or more epoxy groups: including diglycidyl phthalate, diglycidyl hexahydrophthalate, diglycidyl terephthalate, diglycidyl isophthalate, diglycidyl tetrahydrophthalate, diglycidyl methyltetrahydrophthalate, diglycidyl endonucleic acid, diglycidyl adipic acid, diglycidyl 4,5-epoxycyclohexane-1,2-dicarboxylate, bisphenol A type epoxy resin, bisphenol F type epoxy resin, hydrogenated bisphenol A type epoxy resin, tetrabromobisphenol A type epoxy resin, aliphatic alcohol polyglycidyl ether type epoxy resin, linear phenol polyglycidyl ether type epoxy resin, resorcinol type epoxy resin, resorcinol formaldehyde type epoxy resin, tetraphenol ethane type epoxy resin and trishydroxyphenylmethane type epoxy resin, tetraglycidyl diaminodiphenylmethane, triglycidyl triisocyanate, triglycidyl p-aminophenol, diisopropylphenylene type tetraglycidylamine and tetramethylisopropylphenylene tetraglycidylamine, N,N,N',N'-tetracyclyl-4,4'-diaminodiphenylmethane, N,N,N',N'-tetraglycidyl-2,2-bis[4-(4-aminophenoxy)phenyl]propane, N,N,N',N'-tetraglycidyl-4,4'-methylenedi-o-toluidine and 4,4'-diaminodiphenyl ether tetraglycidylamine, bis(3,4-epoxycyclohexylmethyl)adipic acid, epoxy soybean oil or sebacic acid derived epoxy resin.

[0024] The second technical solution of the present invention:

[0025] The present invention also provides a method for preparing the environmentally friendly polypropylene cable insulation material, comprising mixing maleic anhydride grafted polypropylene, maleic anhydride grafted elastomer, polythiol or polyol or epoxy material, and a catalyst, performing melt treatment, and obtaining the environmentally friendly polypropylene cable insulation material by causing a cross-linking reaction.

[0026] The preparation method of the environmentally friendly polypropylene cable insulation material of the present invention uses maleic anhydride grafted polypropylene, maleic anhydride grafted elastomer, polythiol or polyol or epoxy material as raw materials, and adds a catalyst, and melt cross-links at high temperature to react and prepare. The preparation method of the present invention is simple and has a fast reaction rate. The environmentally friendly polypropylene cable insulation material obtained by the present invention has excellent toughness, guarantees mechanical properties at high temperatures, and can retain the recyclable environmental protection characteristics of the polypropylene material. The environmentally friendly polypropylene cable insulation material prepared by the present invention has toughness due to the presence of the elastomer, has excellent mechanical properties due to the presence of the cross-linked structure, and retains the recyclable environmental protection advantage of polypropylene due to the dynamic nature of the cross-linked structure. The environmentally friendly polypropylene cable insulation material of the present invention is suitable for practical applications, and its electrical properties, mechanical properties and thermal properties are greatly improved compared with the existing polypropylene cable insulation materials.

[0027] Preferably, the catalyst is a catalyst capable of catalyzing the ring-opening of thiol / alcohol / epoxy to maleic anhydride; and / or

[0028] The molar ratio of the catalyst to the functional groups participating in the reaction in the polythiol, polyol or epoxy material is 0.01-0.1, wherein the functional groups participating in the reaction in the polythiol are thiol functional groups, the functional groups participating in the reaction in the polyol are hydroxyl functional groups, and the functional groups participating in the reaction in the epoxy material are epoxy functional groups.

[0029] Preferably, the catalyst includes a double metal cyanide complex catalyst, an initiator containing metal ions, a protonic acid, a Fe-Al-bipyridine catalyst system, 1,5,7-triazabicyclo (4.4.0) dec-5-ene, triethylamine, N,N-diisopropylethylamine, pyridine, 1-methyl-1H-imidazole, N-ethylmorpholine, N,N-dimethylbenzylamine or N,Nˋ-diethylpiperazine; more preferably, 1,5,7-triazabicyclo (4.4.0) dec-5-ene.

[0030] In the present invention, polythiol or polyol or epoxy material can be collectively referred to as a crosslinking agent. Such materials can react with the maleic anhydride groups grafted on the polypropylene / elastomer material to form dynamic thioester bonds or dynamic ester bonds, thereby forming a dynamic crosslinking structure between the polypropylene segment and the elastomer segment.

[0031] Preferably, the amount of the crosslinking agent polythiol or polyol or epoxy material added is determined according to the total amount of maleic anhydride in the mixture of maleic anhydride grafted polypropylene and maleic anhydride grafted elastomer and the thiol / hydroxyl / epoxy group in the polythiol or polyol or epoxy material. In terms of molar parts, 1 part of maleic anhydride corresponds to 0.1 to 1.5 parts of thiol / hydroxyl / epoxy groups. With the increase of the crosslinking agent added, more dynamic crosslinking structures will be formed between the polypropylene segments and the elastomer segments in the polypropylene cable insulation material, and a more complex network structure will be formed at the working temperature, which will be beneficial to improve the mechanical properties of the cable insulation material. On the one hand, too much crosslinking agent will introduce excessive polar groups, affecting the electrical properties of the polypropylene insulation material itself. On the other hand, the amount of maleic anhydride is limited, and too much crosslinking agent cannot fully participate in the reaction, resulting in a waste of raw materials.

[0032] Preferably, the mass ratio of the maleic anhydride grafted polypropylene to the maleic anhydride grafted elastomer is 10:(1-6). The addition of the elastomer is to toughen the polypropylene with high hardness and poor toughness. The introduction of the elastomer can significantly improve the elongation at break of the polypropylene cable insulation material, but at the same time it will cause space charge accumulation, reduce the breakdown strength of the cable insulation material, etc., threatening the insulation performance of the material. Therefore, the content of the elastomer needs to be adjusted according to the situation.

[0033] Preferably, the temperature of the melt treatment is 190-300°C and the time is 20-50 minutes. The treatment temperature needs to be above the melting temperature of the raw materials so that the raw materials can be melted and mixed, but too high a processing temperature will reduce the crystallinity of the polypropylene molecular chain, thereby affecting its physical properties, such as significantly reducing strength, toughness, ductility, etc., and high temperature may cause degradation and decomposition reactions of polypropylene.

[0034] The invention introduces a dynamic structure with a dissociation temperature above 105 DEG C into a polypropylene cable insulation material. One feasible scheme is as follows: by weight, 10 parts of maleic anhydride grafted polypropylene and 1 to 6 parts of maleic anhydride grafted polyolefin elastomer are melt-mixed, and the amount of maleic anhydride is obtained according to the total mass of the mixture and the grafting rate. By mole, 0.1 to 1.5 parts of mercapto / hydroxyl / epoxy groups are added to 1 part of maleic anhydride, and 0.01 to 0.1 parts of catalysts are added to 1 part of mercapto / hydroxyl / epoxy groups. The mixtures are melt-mixed and reacted at high temperature (190 to 300 DEG C) to obtain an environmentally friendly polypropylene cable insulation material.

[0035] Compared with the prior art, the present invention has the following advantages and technical effects:

[0036] At present, conventional polypropylene modification methods such as blending and copolymerization have limited effects in achieving high temperature and high strength of modified polypropylene. A beneficial way to improve mechanical strength is to introduce cross-linking, but permanent cross-linking will destroy the environmental advantage of PP's recyclability. The present invention introduces dynamic cross-linking, which is expected to achieve high temperature and high strength while retaining the recyclability of PP, achieving both thermoplasticity and thermosetting. At the same time, combined with the presence of elastomers, the material has the required toughness, which meets the requirements of electrical properties, mechanical properties and thermal properties of cable insulation materials in practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0038] Figure 1 This is the infrared spectra of the polypropylene (SH50) with dynamic thioester bond crosslinking introduced in Example 1 and the polypropylene (SH0) without dynamic crosslinking structure introduced.

[0039] Figure 2 It is the AC breakdown field strength of the polypropylene (SH25 and SH50) with different contents of dynamic thioester bond crosslinking introduced in Examples 1 and 2 and the polypropylene (SH0) without dynamic crosslinking structure introduced in Example 1.

[0040] Figure 3 It is the volume resistivity of the polypropylene (SH25 and SH50) with different contents of dynamic thioester bond crosslinking introduced in Examples 1 and 2 and the polypropylene (SH0) without dynamic crosslinking structure introduced in Example 1.

[0041] Figure 4 The relative dielectric constants at different temperatures are those of the polypropylenes (SH25 and SH50) with different contents of dynamic thioester crosslinking introduced in Examples 1 and 2 and the polypropylene (SH0) without dynamic crosslinking structure introduced in Example 1.

[0042] Figure 5 The dielectric loss tangent at different temperatures of the polypropylenes (SH25 and SH50) with different contents of dynamic thioester bond crosslinking introduced in Examples 1 and 2 and the polypropylene (SH0) without dynamic crosslinking structure introduced in Example 1.

[0043] Figure 6 The stress-strain curves at room temperature are those of the polypropylenes (SH25 and SH50) with different contents of dynamic thioester bond crosslinking introduced in Examples 1 and 2 and the polypropylene (SH0) without dynamic crosslinking structure introduced in Example 1. DETAILED DESCRIPTION

[0044] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0045] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0046] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0047] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0048] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0049] Unless otherwise specified, the room temperature in the present invention is 25±2°C.

[0050] All raw materials used in the embodiments of the present invention can be purchased from the market or prepared by conventional methods in the art.

[0051] In the present invention, grafting rate (%) = (mass of grafted functional groups / total mass of polymer) × 100%

[0052] The preparation method of the environmentally friendly polypropylene cable insulation material of the present invention uses maleic anhydride grafted polypropylene, maleic anhydride grafted elastomer, polythiol or polyol or epoxy material as raw materials, adds a catalyst, and reacts by melting and crosslinking at high temperature to prepare the material. The preparation method of the present invention is simple and has a fast reaction rate. The environmentally friendly polypropylene cable insulation material obtained by the present invention has excellent toughness, ensures mechanical properties at high temperatures, and can retain the recyclable and environmentally friendly characteristics of the polypropylene material.

[0053] The technical solution of the present invention is further illustrated by the following embodiments.

[0054] Example 1

[0055] This embodiment provides an environmentally friendly polypropylene cable insulation material: maleic anhydride grafted polypropylene (purchased from Foshan Nanhai Bochen Polymer New Materials Co., Ltd., model PC-3) with a grafting rate of 1% and maleic anhydride grafted POE elastomer (purchased from Shanghai Langte Industrial Co., Ltd.) are used as raw materials, tetrakis (3-mercaptopropionic acid) pentaerythritol ester (purchased from Aladdin Biochemical Technology Co., Ltd.) is used as a crosslinking agent, and 1,5,7-triazabicyclo (4.4.0) dec-5-ene (TBD) is used as a catalyst. The elastomer content is selected to be 20% (that is, the mass content of maleic anhydride grafted POE elastomer in the mixture of maleic anhydride grafted polypropylene and maleic anhydride grafted POE elastomer is 20%), the molar ratio of thiol to maleic anhydride is 0.5:1, and the molar ratio of thiol to TBD is 1:0.05.

[0056] The preparation method of the above-mentioned environmentally friendly polypropylene cable insulation material is as follows:

[0057] First, the torque rheometer was preheated to 200°C, 20 g of maleic anhydride grafted polypropylene and 5 g of maleic anhydride grafted POE elastomer were weighed, placed in the chamber, and stirred at a speed of 90 r / min for 10 min;

[0058] Then, 0.1527 g of pentaerythritol tetrakis(3-mercaptopropionate) and 0.0087 g of TBD were added, and the mixture was stirred at a rotation speed of 90 r / min for 30 min to obtain an environmentally friendly polypropylene cable insulation material, which was recorded as SH50.

[0059] As a control, a polypropylene cable insulation material without the introduction of thioester bonds was prepared:

[0060] The torque rheometer was preheated to 200°C, 20 g of maleic anhydride grafted polypropylene and 5 g of maleic anhydride grafted POE elastomer were weighed, placed in the cavity, and stirred at a speed of 90 r / min for 10 min. The obtained polypropylene material was recorded as SH0.

[0061] See also Figure 1Fourier transform infrared spectrometer (Nicolet 6700, Thermo Fisher Scientific, USA) was used in attenuated total reflection (ATR) mode with a wavelength range of 4000–400 cm -1 , the chemical structures of SH0 and SH50 were characterized. -1 The peak at SH50 is the characteristic peak corresponding to CO. It is inferred that the higher peak in SH50 is due to the ester bond structure contained in the crosslinking agent pentaerythritol tetra(3-mercaptopropionate); the characteristic peaks of sulfur-containing groups generally appear at 900-1200 cm -1 The position of the sulfide bond (RS-R') is usually between 1100 and 1200 cm -1 The thioester bond (-CO-SR) usually has a strong absorption peak at 1050-1150 cm -1 A strong absorption peak appears at the position of Figure 1 SH50 is shown at 1100cm -1 Characteristic peaks appeared near the surface, verifying the formation of dynamic cross-linking sites in the system.

[0062] Example 2

[0063] This embodiment provides an environmentally friendly polypropylene cable insulation material: maleic anhydride grafted polypropylene (purchased from Foshan Nanhai Bochen Polymer New Materials Co., Ltd., model PC-3) with a grafting rate of 1% and maleic anhydride grafted POE elastomer (purchased from Shanghai Langte Industrial Co., Ltd.) are used as raw materials, tetrakis (3-mercaptopropionic acid) pentaerythritol ester is used as a crosslinking agent, and 1,5,7-triazabicyclo (4.4.0) dec-5-ene (TBD) is used as a catalyst. The elastomer content is selected to be 20%, the molar ratio of mercapto group to maleic anhydride is 0.25:1, and the molar ratio of mercapto group to TBD is 1:0.05.

[0064] The preparation method of the environmentally friendly polypropylene cable insulation material is as follows: first, preheat the torque rheometer to 200° C., weigh 20 g of maleic anhydride grafted polypropylene and 5 g of maleic anhydride grafted POE elastomer, place them in a cavity, and stir at a speed of 90 r / min for 10 min;

[0065] Then, 0.0764 g of pentaerythritol tetrakis(3-mercaptopropionate) and 0.0044 g of TBD were added, and the mixture was stirred at a rotation speed of 90 r / min for 30 min to obtain an environmentally friendly polypropylene cable insulation material, which was recorded as SH25.

[0066] The AC breakdown strength of three samples (i.e., polypropylene (SH25 and SH50) with different contents of dynamic thioester crosslinking introduced in Examples 1 and 2 and polypropylene (SH0) without dynamic crosslinking structure introduced, the same below) was measured using a breakdown instrument (HJC, Huabotech Co., Ltd, China), the electrode diameter was 25mm. A film sample with a thickness of 0.1mm was immersed in silicone oil for a breakdown test, and the voltage was increased at a rate of 0.5kV / s until the sample broke down. The results are shown in Figure 2 , it can be seen that SH25 and SH50 have higher breakdown field strengths, which is closely related to the formation of cross-linked structures, while the reason for the lower breakdown field strength of SH50 may be the higher dynamic bond content and better network dynamics.

[0067] The volume resistivity of the three samples at room temperature was measured using a three-electrode high resistance meter (6517B, Keithley, America). Figure 3 ,Compared with SH0, the volume resistivity of SH25 and SH50 has been greatly improved, and the volume resistivity of SH50 is even greater, which is speculated to be due to the denser and more complex cross-linked network in SH50.

[0068] The dielectric properties of the three samples were tested at different temperatures, such as dielectric constant and loss tangent, using a Xilin bridge tester (QS37a, USA) and a temperature measuring and temperature controller (FY120B, USA). The sample diameter was 10 mm, the thickness was 0.9 mm, the pressure was set to 0.3 MPa, and the temperature range was 30-105 °C. The results are shown in Figure 4 and Figure 5 It can be seen that the dielectric constant of cross-linked polypropylene cable insulation material is small and the loss is slightly reduced. Due to the increase in dynamic sites, the chain entanglement is enhanced, which leads to a decrease in the dielectric constant compared with uncross-linked polypropylene. At the same time, the dielectric loss is relatively low at 30°C and increases rapidly at high temperatures.

[0069] The tensile properties of the samples were tested using a universal testing machine (CMT4503-5kN) according to standard GB / T 1040.3-2006. The results are as follows: Figure 6 As shown in the figure, the tensile strengths of the three samples SH0, SH25 and SH50 are 22.01MPa, 22.77MPa and 23.99MPa respectively. It can be seen that the formation of the cross-linked network improves the tensile strength of the sample.

[0070] Example 3

[0071] This embodiment provides an environmentally friendly polypropylene cable insulation material: maleic anhydride grafted polypropylene (purchased from Shanghai Langte Industrial Co., Ltd.) with a grafting rate of 1% and maleic anhydride grafted POE elastomer (purchased from Shanghai Langte Industrial Co., Ltd.) are used as raw materials, polyethylene glycol (average molecular weight 200, purchased from Aladdin Biochemical Technology Co., Ltd.) is used as a crosslinking agent, and stannous isooctanoate (Sn(Oct)2) (purity ≥98%, purchased from Aladdin Biochemical Technology Co., Ltd.) is used as a catalyst. The elastomer content is selected to be 20%, the molar ratio of hydroxyl to maleic anhydride is 0.5:1, and the molar ratio of hydroxyl to Sn(Oct)2 is 1:0.05.

[0072] The preparation method of the environmentally friendly polypropylene cable insulation material is as follows: first, preheat the torque rheometer to 200° C., weigh 20 g of maleic anhydride grafted polypropylene and 5 g of maleic anhydride grafted POE elastomer, place them in a cavity, and stir at a speed of 90 r / min for 10 min;

[0073] Then, 0.125 g of polyethylene glycol and 0.025 g of Sn(Oct)2 were added, and the mixture was stirred at a rotation speed of 90 r / min for 30 min to obtain an environmentally friendly polypropylene cable insulation material.

[0074] Example 4

[0075] This embodiment provides an environmentally friendly polypropylene cable insulation material: maleic anhydride grafted polypropylene (purchased from Shanghai Langte Industrial Co., Ltd.) with a grafting rate of 1% and maleic anhydride grafted POE elastomer (purchased from Shanghai Langte Industrial Co., Ltd.) are used as raw materials, polyethylene glycol (average molecular weight 200, purchased from Aladdin Biochemical Technology Co., Ltd.) is used as a crosslinking agent, and 1,5,7-triazabicyclo (4.4.0) dec-5-ene (TBD) (purchased from Aladdin Biochemical Technology Co., Ltd.) is used as a catalyst. The elastomer content is selected to be 20%, the molar ratio of hydroxyl to maleic anhydride is 0.5:1, and the molar ratio of hydroxyl to TBD is 1:0.05.

[0076] The preparation method of the environmentally friendly polypropylene cable insulation material is as follows: first, preheat the torque rheometer to 200° C., weigh 20 g of maleic anhydride grafted polypropylene and 5 g of maleic anhydride grafted POE elastomer, place them in a cavity, and stir at a speed of 90 r / min for 10 min;

[0077] Then, 0.125 g of polyethylene glycol and 0.0078 g of TBD were added, and the mixture was stirred at a rotation speed of 90 r / min for 30 min to obtain an environmentally friendly polypropylene cable insulation material.

[0078] Example 5

[0079] This embodiment provides an environmentally friendly polypropylene cable insulation material: maleic anhydride grafted polypropylene (purchased from Shanghai Langte Industrial Co., Ltd.) with a grafting rate of 1% and maleic anhydride grafted POE elastomer (purchased from Shanghai Langte Industrial Co., Ltd.) are used as raw materials, polyethylene glycol (average molecular weight 200, purchased from Aladdin Biochemical Technology Co., Ltd.) is used as a crosslinking agent, and 1,5,7-triazabicyclo (4.4.0) dec-5-ene (TBD) (purchased from Aladdin Biochemical Technology Co., Ltd.) is used as a catalyst. The elastomer content is selected to be 20%, the molar ratio of hydroxyl to maleic anhydride is 1:1, and the molar ratio of hydroxyl to TBD is 1:0.05.

[0080] The preparation method of the environmentally friendly polypropylene cable insulation material is as follows: first, preheat the torque rheometer to 200° C., weigh 20 g of maleic anhydride grafted polypropylene and 5 g of maleic anhydride grafted POE elastomer, place them in a cavity, and stir at a speed of 90 r / min for 10 min;

[0081] Then, 0.25 g of polyethylene glycol and 0.0157 g of TBD were added, and the mixture was stirred at a rotation speed of 90 r / min for 30 min to obtain an environmentally friendly polypropylene cable insulation material.

[0082] Example 6

[0083] This embodiment provides an environmentally friendly polypropylene cable insulation material: maleic anhydride grafted polypropylene (purchased from Shanghai Langte Industrial Co., Ltd.) with a grafting rate of 1% and maleic anhydride grafted POE elastomer (purchased from Shanghai Langte Industrial Co., Ltd.) are used as raw materials, polypropylene glycol (average molecular weight 400, purchased from Aladdin Biochemical Technology Co., Ltd.) is used as a crosslinking agent, and stannous isooctanoate (Sn(Oct)2) (purity ≥98%, purchased from Aladdin Biochemical Technology Co., Ltd.) is used as a catalyst. The elastomer content is selected to be 20%, the molar ratio of hydroxyl to maleic anhydride is 0.5:1, and the molar ratio of hydroxyl to Sn(Oct)2 is 1:0.05.

[0084] The preparation method of the environmentally friendly polypropylene cable insulation material is as follows: first, preheat the torque rheometer to 200° C., weigh 20 g of maleic anhydride grafted polypropylene and 5 g of maleic anhydride grafted POE elastomer, place them in a cavity, and stir at a speed of 90 r / min for 10 min;

[0085] Then, 0.25 g of polypropylene glycol and 0.025 g of Sn(Oct)2 were added, and the mixture was stirred at a rotation speed of 90 r / min for 30 min to obtain an environmentally friendly polypropylene cable insulation material.

[0086] Example 7

[0087] This embodiment provides an environmentally friendly polypropylene cable insulation material: maleic anhydride grafted polypropylene with a grafting rate of 1% (purchased from Shanghai Langte Industrial Co., Ltd.) and maleic anhydride grafted ethylene propylene rubber elastomer with a grafting rate of 1.18% (purchased from Dongguan Jingke Polymer Materials) are used as raw materials, polyethylene glycol (average molecular weight 200, purchased from Aladdin Biochemical Technology Co., Ltd.) is used as a crosslinking agent, and 1,5,7-triazabicyclo (4.4.0) dec-5-ene (TBD) (purchased from Aladdin Biochemical Technology Co., Ltd.) is used as a catalyst. The elastomer content is selected to be 20%, the molar ratio of hydroxyl to maleic anhydride is 0.5:1, and the molar ratio of hydroxyl to Sn(Oct)2 is 1:0.05.

[0088] The preparation method of the environmentally friendly polypropylene cable insulation material is as follows: first, preheat the torque rheometer to 200°C, weigh 20g of maleic anhydride grafted polypropylene and 5g of maleic anhydride grafted ethylene propylene rubber elastomer, place them in the cavity, and stir at a speed of 90r / min for 10min;

[0089] Then, 0.145 g of polyethylene glycol and 0.029 g of Sn(Oct)2 were added, and the mixture was stirred at a rotation speed of 90 r / min for 30 min to obtain an environmentally friendly polypropylene cable insulation material.

[0090] Example 8

[0091] This embodiment provides an environmentally friendly polypropylene cable insulation material: maleic anhydride grafted polypropylene (purchased from Shanghai Langte Industrial Co., Ltd.) with a grafting rate of 1% and maleic anhydride grafted POE elastomer (purchased from Shanghai Langte Industrial Co., Ltd.) are used as raw materials, bisphenol A epoxy resin (E51, purchased from Nantong Xingchen Synthetic Materials Co., Ltd.) is used as a crosslinking agent, and triethanolamine (TEOA) (purity ≥ 98%, purchased from Aladdin Biochemical Technology Co., Ltd.) is used as a catalyst. The elastomer content is selected to be 20%, the molar ratio of epoxy group to maleic anhydride is 0.5:1, and the molar ratio of epoxy group to TEOA is 1:0.05.

[0092] The preparation method of the environmentally friendly polypropylene cable insulation material is as follows: first, preheat the torque rheometer to 200° C., weigh 20 g of maleic anhydride grafted polypropylene and 5 g of maleic anhydride grafted POE elastomer, place them in a cavity, and stir at a speed of 90 r / min for 10 min;

[0093] Then, 0.245 g of bisphenol A epoxy resin and 0.0093 g of TEOA were added, and the mixture was stirred at a rotation speed of 90 r / min for 30 min to obtain an environmentally friendly polypropylene cable insulation material.

[0094] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. An environmentally friendly polypropylene cable insulation material, characterized in that: The environmentally friendly polypropylene cable insulation material has a cross-linked structure shown in formula (I) or formula (II): In formula (I) and formula (II), X is the part of polythiol of different structures excluding the thiol functional group, or the part of polyol excluding the hydroxyl functional group, or the part of epoxy material excluding the epoxy functional group; the solid line frame is the dynamic crosslinking part, which is connected between the polypropylene segments, between the elastomer segments, or between the polypropylene and the elastomer; the dotted line frame is the specific dynamic crosslinking site.

2. The environmentally friendly polypropylene cable insulation material according to claim 1, characterized in that: The raw materials of the environmentally friendly polypropylene cable insulation material include: maleic anhydride grafted polypropylene, maleic anhydride grafted elastomer and one of polythiol, polyol and epoxy material.

3. The environmentally friendly polypropylene cable insulation material according to claim 2, characterized in that: The maleic anhydride grafted elastomer is a product obtained by grafting maleic anhydride onto an elastic material, and the elastic material is an elastic material capable of overcoming the rigidity and brittleness of polypropylene; and / or The polythiol is a thiol containing two thiol groups or a thiol containing three or more thiol groups; and / or The polyol is an alcohol containing two hydroxyl groups or an alcohol containing three or more hydroxyl groups; and / or The epoxy material is a material containing two or more epoxy groups.

4. The environmentally friendly polypropylene cable insulation material according to claim 3, characterized in that: The elastic material includes ethylene propylene rubber, ethylene propylene diene monomer rubber, styrene-butadiene-styrene block copolymer, polystyrene-polyethylene-polybutylene polystyrene copolymer, polyolefin elastomer, ethylene-1-octene block copolymer or ethylene-vinyl acetate copolymer.

5. The environmentally friendly polypropylene cable insulation material according to claim 3, characterized in that: The polythiol includes 1,4-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, 1,7-heptanedithiol, 1,8-octanedithiol, 1,9-nonanedithiol, 1,10-decanedithiol, 2,6-dimercaptopurine, 1,4-benzenedithiol, 1,4-benzenedimethanethiol, 3,6-dioxa-1,8-octanedithiol, toluene-3,4-dithiol, 4,4'-thiobisbenzenedithiophenol, trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetra(3-mercaptopropionate) or pentaerythritol tetra(3-mercaptobutyrate).

6. The environmentally friendly polypropylene cable insulation material according to claim 3, characterized in that: The polyol includes polyethylene glycol, polypropylene glycol, polybutylene glycol, glycerol, trimethylolpropane, sorbitol or fructose alcohol.

7. The environmentally friendly polypropylene cable insulation material according to claim 3, characterized in that: The epoxy material includes diglycidyl phthalate, diglycidyl hexahydrophthalate, diglycidyl terephthalate, diglycidyl isophthalate, diglycidyl tetrahydrophthalate, diglycidyl methyltetrahydrophthalate, diglycidyl endomethyltetrahydrophthalate, diglycidyl adipate, diglycidyl 4,5-epoxycyclohexane-1,2-dicarboxylate, bisphenol A type epoxy resin, bisphenol F type epoxy resin, hydrogenated bisphenol A type epoxy resin, tetrabromobisphenol A type epoxy resin, aliphatic alcohol polyglycidyl ether type epoxy resin, linear phenol polyglycidyl ether type epoxy resin, resorcinol type epoxy resin, resorcinol-formaldehyde type epoxy resin, tetraphenol-based ethyl Alkane type epoxy resin and trishydroxyphenylmethane type epoxy resin, tetraglycidyl diaminodiphenylmethane, triglycidyl triisocyanate, triglycidyl p-aminophenol, diisopropylphenylene type tetraglycidylamine and tetramethylisopropylphenylene tetraglycidylamine, N,N,N',N'-tetracyclyl-4,4'-diaminodiphenylmethane, N,N,N',N'-tetraglycidyl-2,2-bis[4-(4-aminophenoxy)phenyl]propane, N,N,N',N'-tetraglycidyl-4,4'-methylenedi-o-toluidine and 4,4'-diaminodiphenyl ether tetraglycidylamine, bis(3,4-epoxycyclohexylmethyl)adipic acid, epoxy soybean oil or sebacic acid derived epoxy resin.

8. A method for preparing the environmentally friendly polypropylene cable insulation material according to any one of claims 1 to 7, characterized in that: The maleic anhydride grafted polypropylene, the maleic anhydride grafted elastomer, the polythiol or polyol or epoxy material and the catalyst are mixed, melt-treated and cross-linked to obtain the environmentally friendly polypropylene cable insulation material.

9. The method for preparing the environmentally friendly polypropylene cable insulation material according to claim 8, characterized in that: The catalyst is a catalyst capable of catalyzing the ring-opening of thiol / alcohol / epoxy maleic anhydride; and / or The molar ratio of the catalyst to the functional groups participating in the reaction in the polythiol, polyol or epoxy material is 0.01 to 0.

1.

10. The method for preparing the environmentally friendly polypropylene cable insulation material according to claim 9, characterized in that: The catalyst includes a double metal cyanide complex catalyst, an initiator containing metal ions, a protonic acid, a Fe-Al-bipyridine catalyst system, 1,5,7-triazabicyclo (4.4.0) dec-5-ene, triethylamine, N,N-diisopropylethylamine, pyridine, 1-methyl-1H-imidazole, N-ethylmorpholine, N,N-dimethylbenzylamine or N,N'-diethylpiperazine.

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