High-voltage cable polypropylene insulating material, preparation method therefor, and use thereof

Abstract

A high-voltage cable polypropylene insulating material is provided in the present application, wherein using a polypropylene in-reactor alloy resin as a composite material skeleton can endow the high-voltage cable polypropylene insulating material with excellent heat resistance; and a thermoplastic polyolefin elastomer can induce interface shear bands or crazes, and therefore by means of the shear bands or crazes, can dissipate the energy acted by the external force, so that the high-voltage cable polypropylene insulating material can hold an excellent mechanical strength even at a high temperature. In addition, the polypropylene in-reactor alloy resin and the thermoplastic polyolefin elastomer in said insulating material have good compatibility, and thus enable the high-voltage cable polypropylene insulating material to have relatively low bending modulus and relatively high breakdown field strength. Therefore, said insulating material has excellent toughness and electrical properties, thereby satisfying application conditions of high-voltage cable polypropylene insulating materials.

Description

High-voltage cable polypropylene insulation material and preparation method and application thereof TECHNICAL FIELD

[0001] The present application relates to the field of power engineering materials, in particular to a high-voltage cable polypropylene insulation material and a preparation method and application thereof. BACKGROUND

[0002] High-voltage cable is a kind of power cable, which plays an important role in national power transmission and distribution, smart grid construction, etc. At present, cross-linked polyethylene is mainly used as the main insulation material of high-voltage cable. The heat resistance of cross-linked polyethylene insulation cable is poor, which cannot meet the use requirements of larger capacity power transmission systems. At the same time, polyethylene cable cannot be recycled after its service life, resulting in a large amount of waste and posing a serious challenge to environmental protection.

[0003] Thermoplastic polypropylene high-voltage cable has the characteristics of high operating temperature and recyclability, and becomes a new generation of environmentally friendly cable that can replace cross-linked polyethylene. However, polypropylene as a cable insulation material cannot have excellent heat resistance and toughness at the same time.

[0004] SUMMARY

[0005] Therefore, the present application provides a high-voltage cable polypropylene insulation material and a preparation method and application thereof. The high-voltage cable polypropylene insulation material has excellent heat resistance and toughness.

[0006] In a first aspect of the present application, a high-voltage cable polypropylene insulation material is provided, which comprises the following components by weight fraction:

[0007] polypropylene in-reactor alloy resin 30-60 parts,

[0008] thermoplastic polyolefin elastomer 40-70 parts, and

[0009] antioxidant 0.3-1 part.

[0010] In one embodiment, the polypropylene in-reactor alloy resin comprises a rubber phase and a homopolymer polypropylene in a mass ratio of 1:(3-4).

[0011] In one embodiment, the homopolymer polypropylene has an isotacticity of ≥95%.

[0012] In one embodiment, the rubber phase in the polypropylene in-reactor alloy resin has a phase size of 0.2-1 μm.

[0013] In one embodiment, the rubber phase is selected from ethylene-propylene random copolymer.

[0014] In one of the embodiments, the thermoplastic polyolefin elastomer has one or more of the following characteristics:

[0015] (1) the thermoplastic polyolefin elastomer has a density of 0.85 g / cm3to 0.89 g / cm3;

[0016] (2) the thermoplastic polyolefin elastomer has a melt index of 0.5 g / 10 min to 0.8 g / 10 min at 230℃ under a load of 2.16 kg;

[0017] (3) the thermoplastic polyolefin elastomer is selected from polypropylene.

[0018] In one of the embodiments, the antioxidant is selected from hindered phenolic antioxidants.

[0019] In a second aspect of the present application, a preparation method of the high-voltage cable polypropylene insulation material according to any one of the embodiments of the first aspect of the present application is provided, and the preparation method comprises the following steps:

[0020] The polypropylene in-reactor alloy, the thermoplastic polyolefin elastomer and the antioxidant are melt blended in weight fractions, and the high-voltage cable polypropylene insulation material is prepared after extrusion;

[0021] In one of the embodiments, the temperature for melt blending is 150℃ to 200℃.

[0022] In one of the embodiments, the time for melt blending is 5 min to 15 min.

[0023] In a third aspect of the present application, the high-voltage cable polypropylene insulation material according to any one of the embodiments of the first aspect of the present application is applied to high-voltage AC cable insulation materials.

[0024] In the high-voltage cable polypropylene insulation material provided by the present application, the polypropylene in-reactor alloy resin serves as a composite material framework, which can enable the high-voltage cable polypropylene insulation material to have excellent heat resistance; meanwhile, the thermoplastic polyolefin elastomer can induce interface shear bands or crazes, and thus can enable the energy of external force to be dissipated through the shear bands or crazes, so that the high-voltage cable polypropylene insulation material can also maintain excellent mechanical strength at high temperatures; and the polypropylene in-reactor alloy resin and the thermoplastic polyolefin elastomer in the present application have good compatibility, which can enable the high-voltage cable polypropylene insulation material to have a lower flexural modulus and a higher breakdown field strength, so that the high-voltage cable polypropylene insulation material has excellent toughness and electrical properties, and can meet the application conditions of the high-voltage cable polypropylene insulation material. BRIEF DESCRIPTION OF DRAWINGS

[0025] FIG. 1 is a flexural modulus column chart of the high-voltage cable polypropylene insulation material prepared in Examples 1 to 4 and Comparative Examples 1 and 2 of the present application;

[0026] Figure 2 is a column chart of breakdown field strength of polypropylene insulating material of high voltage cable prepared in Examples 1-4 and Comparative Examples 1-2 of the present application;

[0027] Figure 3 is a melting temperature curve of polypropylene insulating material of high voltage cable prepared in Examples 1-4 and Comparative Examples 1-2 of the present application. DETAILED DESCRIPTION

[0028] The high voltage cable polypropylene insulating material of the present application, the preparation method and application thereof will be further described in detail below in conjunction with specific examples. The present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0030] Herein, "one or more" means any one, any two or more than two of the listed items.

[0031] In the present application, "first aspect", "second aspect", "third aspect", "fourth aspect", "fifth aspect" and the like are only for the purpose of description and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the technical features indicated.

[0032] In the present application, the technical features described in an open-ended manner include both a closed technical solution consisting of the listed features and an open technical solution containing the listed features.

[0033] In the present application, when referring to a numerical interval, the numerical interval is considered to be continuous and includes the minimum value and the maximum value of the range and each value between the minimum value and the maximum value, unless otherwise specified. Further, when the range refers to an integer, each integer between the minimum value and the maximum value of the range is included. In addition, when multiple ranges are provided to describe a feature or a characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges encompassed therein.

[0034] In the present application, the percentage content, unless otherwise specified, refers to mass percentage for solid-liquid mixing and solid-solid mixing, and refers to volume percentage for liquid-liquid mixing.

[0035] The percentage concentration referred to in the present application, if not specified, refers to the final concentration. The final concentration refers to the proportion of the added component in the system after the component is added.

[0036] The temperature parameter in the present application, if not specifically limited, allows both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument.

[0037] In the present application, unless otherwise specified, the "isotacticity" refers to the mass fraction of stereoregular polymer in the total polymer, which is used to represent the degree of stereoregularity of isotactic polymer.

[0038] In a first aspect of the present application, a high-voltage cable polypropylene insulation material is provided, the raw materials of which comprise the following components in parts by weight:

[0039] Polypropylene in-reactor alloy resin 30-60 parts,

[0040] Thermoplastic polyolefin elastomer 40-70 parts, and

[0041] Antioxidant 0.3-1 part.

[0042] In the high-voltage cable polypropylene insulation material provided by the present application, the polypropylene in-reactor alloy resin serves as the framework of the composite material, which can make the high-voltage cable polypropylene insulation material have excellent heat resistance; at the same time, the thermoplastic polyolefin elastomer can induce interfacial shear band or craze, thereby enabling the energy of external force to be dissipated through the shear band or craze, so that the high-voltage cable polypropylene insulation material can also maintain excellent mechanical strength at high temperatures; and the compatibility of the polypropylene in-reactor alloy resin and the thermoplastic polyolefin elastomer in the present application is good, which can make the high-voltage cable polypropylene insulation material have a lower bending modulus and a higher breakdown field strength, so that it has excellent toughness and electrical properties, which can meet the application conditions of high-voltage cable polypropylene insulation material.

[0043] It can be understood that the weight fraction of the polypropylene in-situ alloy resin can be selected from any value between 30 parts and 60 parts. Specifically, the weight fraction of the polypropylene in-situ alloy resin includes but is not limited to 30 parts, 35 parts, 38 parts, 40 parts, 45 parts, 50 parts, 52 parts, 55 parts, 58 parts or 60 parts. The weight fraction of the thermoplastic polyolefin elastomer can be selected from any value between 40 parts and 70 parts. Specifically, the weight fraction of the thermoplastic polyolefin elastomer includes but is not limited to 40 parts, 45 parts, 48 parts, 49 parts, 50 parts, 52 parts, 55 parts, 58 parts, 60 parts, 61 parts, 62 parts, 65 parts or 70 parts. The weight fraction of the antioxidant can be selected from any value between 0.3 parts and 1 part. Specifically, the weight fraction of the antioxidant includes but is not limited to 0.3 parts, 0.5 parts, 0.7 parts, 0.9 parts or 1 part.

[0044] As preferred, the polypropylene in-situ alloy resin for high-voltage cable insulation material, in terms of weight fraction, includes the following components:

[0045] polypropylene in-situ alloy resin 38 parts to 52 parts,

[0046] thermoplastic polyolefin elastomer 48 parts to 62 parts, and

[0047] antioxidant 0.3 parts to 1 part.

[0048] In one of the examples, the polypropylene in-situ alloy resin includes a rubber phase and a homopolymer polypropylene with a mass ratio of 1:(3-4).

[0049] In one of the examples, the homopolymer polypropylene has a degree of isotacticity ≥ 95%.

[0050] The conventional polypropylene in-situ alloy resin has the disadvantages of insufficient toughness, poor electrical performance, low breakdown field strength and poor thermal stability in high-temperature environment as a high-voltage insulation material. By selecting a homopolymer polypropylene with a degree of isotacticity ≥ 95%, the present application can ensure the regularity of the molecular chain, and in the cooperation of a certain weight fraction of rubber, the polypropylene in-situ alloy resin has high crystallinity and large rigidity, which can make the obtained polypropylene in-situ alloy resin as a composite material skeleton to improve the temperature resistance of the polypropylene in-situ alloy resin for high-voltage cable insulation material. Optionally, the weight fraction of the homopolymer polypropylene includes but is not limited to 80 parts, 82 parts, 85 parts, 90 parts, 93 parts or 95 parts. The weight fraction of the rubber includes but is not limited to 5 parts, 8 parts, 10 parts, 15 parts or 20 parts. The degree of isotacticity of the homopolymer polypropylene includes but is not limited to 95%, 96%, 97%, 98% or 99%.

[0051] In one example, the rubber phase in the polypropylene reactor alloy resin has a phase size of 0.2 to 1 μm. By limiting the phase size of the rubber phase, the influence of the rubber phase on the heat resistance of the polypropylene reactor alloy resin can be reduced.

[0052] In one specific example, the rubber phase is selected from ethylene-propylene random copolymer.

[0053] In one example, the thermoplastic polyolefin elastomer has a density of 0.85 g / cm 3 to 0.89 g / cm 3 . It is understood that the thermoplastic polyolefin elastomer can have a density selected from any value between 0.85 g / cm 3 to 0.89 g / cm 3 . In particular, the thermoplastic polyolefin elastomer can have a density selected from, but not limited to, 0.85 g / cm 3 , 0.86 g / cm 3 , 0.87 g / cm 3 , 0.88 g / cm 3 , or 0.89 g / cm 3 .

[0054] In one example, the thermoplastic polyolefin elastomer has a melt index of 0.5 g / 10 min to 0.8 g / 10 min at 230 °C under a 2.16 kg load. It is understood that the thermoplastic polyolefin elastomer can have a melt index selected from any value between 0.5 g / 10 min to 0.8 g / 10 min at 230 °C under a 2.16 kg load. In particular, the thermoplastic polyolefin elastomer can have a melt index selected from, but not limited to, 0.5 g / 10 min, 0.6 g / 10 min, 0.7 g / 10 min, or 0.8 g / 10 min. The density and the melt index of the thermoplastic polyolefin elastomer selected in this range can improve the mechanical toughness of the polypropylene insulation material for high voltage cables.

[0055] In one example, the thermoplastic polyolefin elastomer comprises one or more of ethylene-octene copolymer, polyethylene, ethylene-vinyl acetate copolymer, polypropylene, and ethylene-propylene rubber. Preferably, the thermoplastic polyolefin elastomer is selected from polypropylene elastomer comprising 50 to 70 parts by weight of ethylene-propylene rubber and 30 to 50 parts by weight of polypropylene; this can ensure the dispersibility of the polypropylene and can enhance the compatibility of the thermoplastic polyolefin elastomer with the polypropylene reactor alloy.

[0056] The antioxidant can prevent the high-voltage cable polypropylene insulation material from aging. In one example, the antioxidant is selected from hindered phenolic antioxidants. The antioxidant can be, for example, [beta-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] pentaerythrityl ester, dilauryl thiodipropionate, and phosphite antioxidant.

[0057] In one example, the high-voltage cable polypropylene insulation material has a bending modulus of 100 MPa to 600 MPa. The high-voltage cable polypropylene insulation material provided herein has a moderate bending modulus, which makes it have excellent toughness. A low bending modulus will result in insufficient cable rigidity when used in a cable, affecting the long-term creep resistance of the cable; a high bending modulus will result in insufficient toughness of the high-voltage cable polypropylene insulation material, which cannot meet the requirements of the cable.

[0058] In one example, the high-voltage cable polypropylene insulation material has a load elongation of ≤ 13%.

[0059] In one example, the high-voltage cable polypropylene insulation material has a permanent deformation rate of ≤ 11%.

[0060] The high-voltage cable polypropylene insulation material provided herein has excellent low modulus, high elasticity, and excellent mechanical properties, which greatly reduces the bending modulus of the composite material and makes it have excellent toughness.

[0061] In one example, the high-voltage cable polypropylene insulation material has a breakdown field strength of ≥ 130 MV / m. The high-voltage cable polypropylene insulation material provided herein has a high breakdown field strength and excellent electrical properties.

[0062] In a second aspect, the application provides a method for preparing the high-voltage cable polypropylene insulation material of any one of the examples of the first aspect of the application, comprising the following steps:

[0063] The polypropylene in-reactor alloy, the thermoplastic polyolefin elastomer, and the antioxidant are melt blended in a weight ratio, and the high-voltage cable polypropylene insulation material is prepared after extrusion.

[0064] In one example, the temperature for melt blending is 150°C to 200°C. It can be understood that the temperature for melt blending can be selected from any value between 150°C and 220°C. Specifically, the temperature values include, but are not limited to, 150°C, 180°C, 190°C, 200°C, 210°C, or 220°C.

[0065] In one example, the time for melt blending is 5 min to 15 min. It can be understood that the mixing time can be selected from any value between 5 min and 15 min. Specifically, the mixing time values include, but are not limited to, 5 min, 8 min, 12 min, 13 min, or 15 min.

[0066] In one example, the mixing process parameters include: the rotation speed is set to 80 r / min-180 r / min. It can be understood that the rotation speed can be set to any value between 80 r / min-180 r / min. Specifically, the rotation speed includes but is not limited to 80 r / min, 85 r / min, 90 r / min, 95 r / min, 100 r / min, 130 r / min, 150 r / min or 180 r / min. The setting of the mixing process parameters can enhance the dispersibility and compatibility of the components of the high-voltage cable polypropylene insulation material.

[0067] In a third aspect, the application provides a use of the high-voltage cable polypropylene insulation material of any one of the examples of the application in a high-voltage AC cable insulation material. The high-voltage cable polypropylene insulation material provided by the application has wide application. For example, the high-voltage cable polypropylene insulation material can be applied to a 110-kilovolt high-voltage AC cable.

[0068] The following are specific examples. Unless otherwise specified, the raw materials used in the examples are commercially available products.

[0069] Example 1

[0070] 60 parts of polypropylene-based in-kettle alloy resin (the mass ratio of the rubber phase to the homopolymer polypropylene is 1:4; the isotacticity of the homopolymer polypropylene is ≥95%; the rubber phase size is 0.2-1.0 μm, and the rubber phase is an ethylene-propylene random copolymer), 40 parts of thermoplastic polypropylene elastomer (the density is 0.89 g / cm 3 , the melt index (230℃× 2.16kg) is 0.8 g / 10 min), 0.3 parts of antioxidant (hindered phenolic antioxidant 1010, commercially available) are weighed as raw materials, and are placed in a mixing machine for melt blending and extrusion to obtain a high-voltage cable polypropylene insulation material. The melt blending process is: the temperature is 200℃, the time is 15 minutes, and the rotation speed is 90 r / min.

[0071] Example 2

[0072] 50 parts of polypropylene-based in-kettle alloy resin (the mass ratio of the rubber phase to the homopolymer polypropylene is 1:4; the isotacticity of the homopolymer polypropylene is ≥95%; the rubber phase size is 0.2-1.0 μm, and the rubber phase is an ethylene-propylene random copolymer), 50 parts of thermoplastic polypropylene elastomer (the density is 0.89 g / cm 3The following raw materials were used: a melt flow index (230℃×2.16kg) of 0.8g / 10min and an antioxidant (hindered phenolic antioxidant 1010, commercially available). These were melt-blended and extruded in an internal mixer to obtain high-voltage cable polypropylene insulation material. The melt-blending process was as follows: temperature 200℃, time 15 minutes, and rotation speed 90r / min.

[0073] Example 3

[0074] Weigh out 40 parts of polypropylene-based autoclave alloy resin (the mass ratio of rubber phase to homopolymer polypropylene is 1:4; the isotacticity of homopolymer polypropylene is ≥95%; the phase size of the rubber phase is 0.2~1.0μm, and the rubber phase is an ethylene-propylene random copolymer) and 60 parts of thermoplastic polypropylene elastomer (density is 0.89g / cm³). 3 The following raw materials were used: a melt flow index (230℃×2.16kg) of 0.8g / 10min and an antioxidant (hindered phenolic antioxidant 1010, commercially available). These were melt-blended and extruded in an internal mixer to obtain high-voltage cable polypropylene insulation material. The melt-blending process was as follows: temperature 200℃, time 15 minutes, and rotation speed 90r / min.

[0075] Example 4

[0076] Weigh out 30 parts of polypropylene-based autoclave alloy resin (the mass ratio of rubber phase to homopolymer polypropylene is 1:4; the isotacticity of homopolymer polypropylene is ≥95%; the phase size of the rubber phase is 0.2~1.0μm, and the rubber phase is an ethylene-propylene random copolymer) and 70 parts of thermoplastic polypropylene elastomer (density is 0.89g / cm³). 3 The following raw materials were used: a melt flow index (230℃×2.16kg) of 0.8g / 10min and an antioxidant (hindered phenolic antioxidant 1010, commercially available). These were melt-blended and extruded in an internal mixer to obtain high-voltage cable polypropylene insulation material. The melt-blending process was as follows: temperature 200℃, time 15 minutes, and rotation speed 90r / min.

[0077] Example 5

[0078] Weigh out 30 parts of polypropylene-based autoclave resin (the mass ratio of rubber phase to homopolymer polypropylene is 1:3; the isotacticity of homopolymer polypropylene is ≥95%; the phase size of the rubber phase is 0.2-1.0 μm, and the rubber phase is an ethylene-propylene random copolymer) and 70 parts of thermoplastic polypropylene elastomer (density is 0.85 g / cm³). 3 A high-voltage cable polypropylene insulation material was obtained by melt blending and extruding a mixture of raw materials, including a melt index (230℃×2.16kg) of 0.5g / 10min and one part antioxidant, in a Banbury mixer. The melt blending process was as follows: temperature 150℃, time 5 minutes, and rotation speed 90r / min.

[0079] Comparative Example 1

[0080] Take 70 parts of polypropylene alloy resin (rubber phase and the mass ratio of homopolymer polypropylene is 1:4; the isotacticity of homopolymer polypropylene is greater than or equal to 95%; the rubber phase size is 0.2-1.0 μm, and the rubber phase is ethylene-propylene random copolymer), 30 parts of thermoplastic polypropylene elastomer (the density is 0.89 g / cm 3 , the melt index (230℃×2.16 kg) is 0.8 g / 10 min), antioxidant (hindered phenolic antioxidant 1010, commercially available) 0.3 parts as raw materials, melt blend in the internal mixer, extrusion, get high voltage cable polypropylene insulation material. The melt blending process is: temperature 200℃, time is 15 minutes, the speed is 90 r / min.

[0081] Comparative Example 2

[0082] Take 20 parts of polypropylene alloy resin (rubber phase and the mass ratio of homopolymer polypropylene is 1:4; the isotacticity of homopolymer polypropylene is greater than or equal to 95%; the rubber phase size is 0.2-1.0 μm, and the rubber phase is ethylene-propylene random copolymer), 80 parts of thermoplastic polypropylene elastomer (the density is 0.89 g / cm 3 , the melt index (230℃×2.16 kg) is 0.8 g / 10 min), antioxidant (hindered phenolic antioxidant 1010, commercially available) 0.3 parts as raw materials, melt blend in the internal mixer, extrusion, get high voltage cable polypropylene insulation material. The melt blending process is: temperature 200℃, time is 15 minutes, the speed is 90 r / min.

[0083] Comparative Example 3

[0084] Take 100 parts of polypropylene alloy resin (rubber phase and the mass ratio of homopolymer polypropylene is 1:4; the isotacticity of homopolymer polypropylene is greater than or equal to 95%; the rubber phase size is 0.2-1.0 μm, and the rubber phase is ethylene-propylene random copolymer), antioxidant (hindered phenolic antioxidant 1010, commercially available) 0.3 parts as raw materials, melt blend in the internal mixer, extrusion, get high voltage cable polypropylene insulation material. The melt blending process is: temperature 200℃, time is 15 minutes, the speed is 90 r / min.

[0085] Comparative Example 4

[0086] Take 100 parts of homopolymer polypropylene, 0.3 parts of antioxidant (hindered phenolic antioxidant 1010, commercially available) as raw materials, melt blend in the internal mixer, extrusion, get high voltage cable polypropylene insulation material. The melt blending process is: temperature 200℃, time is 15 minutes, the speed is 90 r / min.

[0087] The high-voltage cable polypropylene insulating material prepared by the examples and comparative examples was characterized and tested in terms of bending modulus, crystal structure and heat resistance.

[0088] The test method or standard is:

[0089] (1) Bending modulus: tested according to GB / T9341-2008;

[0090] (2) Electrical properties: tested according to GB / T 1408.1-2016;

[0091] (3) Crystal structure: characterization was performed by using a differential scanning calorimeter (TAQ250), about 5 mg sample was placed in an open crucible, heated from room temperature to 200℃ at a heating rate of 10℃ / min under nitrogen atmosphere, and the change of heat flow signal with temperature was recorded.

[0092] (4) Heat resistance test: to evaluate whether the insulating material can maintain the necessary mechanical strength at the desired overload temperature, the sample was prepared according to the tensile property test method. The standard test method for heat extension test was used. One end of the sample was hung in an oven, the oven temperature was set to 150℃, the other end was subjected to a 0.2 MPa tensile force conversion mass weight according to the cross section of the sample, after setting time of 15 min, the elongation of the sample was measured, defined as the elongation under load. The elongation after cooling was defined as the permanent deformation rate.

[0093] The test results are shown in Table 1:

[0094] Table 1

[0095] As can be seen from the results of Table 1 and Figures 1-3, the insulating materials prepared in Examples 1-4 have suitable bending modulus, which can ensure the rigidity and toughness of the insulating material; at the same time, the insulating materials prepared in Examples 1-4 have high crystallinity and high melting temperature, and the load elongation and permanent deformation rate are small at high temperature, which indicates that the insulating materials obtained in Examples have excellent heat resistance; and the breakdown field strength is high, which indicates that it has excellent electrical stability; therefore, the insulating material provided in the application has excellent comprehensive performance. In Example 5, the increase of the content of polypropylene kettle alloy rubber phase and the decrease of the density of polypropylene elastomer are beneficial to increase the mechanical toughness; more antioxidants can reduce the electrical insulation performance to a certain extent, but it is still at a high level. Mainly due to the existence of polypropylene crystal skeleton, good thermal stability can still be maintained.

[0096] Although the polypropylene insulation material prepared by Comparative Example 1 has a small elongation under load and a small permanent set at high temperature, the bending modulus thereof is too high (>600 MPa), and the material toughness is insufficient, which cannot meet the requirements of the cable. The bending modulus of the polypropylene insulation material prepared by Comparative Example 2 is slightly low, and the material rigidity is slightly weak. Moreover, the polypropylene insulation material prepared by Comparative Example 2 has poor heat resistance, and the deformation amount of the sample under load is too large during the test, directly reaching the bottom of the oven, and no exact value is obtained. The polypropylene insulation materials prepared by Comparative Examples 3 and 4 both have a bending modulus that is too high, are easy to deform, and have insufficient material toughness, which cannot meet the actual use requirements.

[0097] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, but it should be considered that any combination of the technical features is within the scope of the present disclosure as long as the combination does not result in contradictions.

[0098] The above-described embodiments only express several implementation manners of the present application, facilitate the understanding of the technical solutions of the present application, and should not be considered as limitations on the patent protection scope of the present application. It should be noted that, for those skilled in the art, some modifications and improvements can be made without departing from the concept of the present application, and these modifications and improvements are also within the protection scope of the present application. It should be understood that, on the basis of the technical solutions provided by the present application, the technical solutions obtained by logical analysis, reasoning or limited experiments by those skilled in the art are also within the protection scope of the appended claims of the present application. Therefore, the patent protection scope of the present application should be subject to the contents of the appended claims, and the description can be used to explain the contents of the claims.

Claims

1. A polypropylene insulation material for high-voltage cables, characterized in that, Its raw materials, by weight, include the following components: 30 to 60 parts of alloying resin in the polypropylene autoclave 40 to 70 parts of thermoplastic polyolefin elastomer, and Antioxidant 0.3 to 1 part.

2. The polypropylene insulation material for high-voltage cables according to claim 1, characterized in that, The polypropylene in-reactor alloy resin comprises a rubber phase and homopolymer polypropylene in a mass ratio of 1:(3-4).

3. The high-voltage cable polypropylene insulation material according to claim 2, characterized in that, The isotacticity of the homopolymer polypropylene is ≥95%.

4. The polypropylene insulation material for high-voltage cables according to claim 2, characterized in that, The phase size of the rubber phase in the alloy resin inside the polypropylene reactor is 0.2–1 μm.

5. The high-voltage cable polypropylene insulation material according to claim 2, characterized in that, The rubber phase is selected from ethylene-propylene random copolymer.

6. The high-voltage cable polypropylene insulation material according to any one of claims 1 to 5, characterized in that, The thermoplastic polyolefin elastomer has one or more of the following characteristics: (1) The density of the thermoplastic polyolefin elastomer is 0.85 g / cm³. 3 ~0.89g / cm 3 ; (2) The melt index of the thermoplastic polyolefin elastomer at 230℃ × 2.16kg load is 0.5g / 10min~0.8g / 10min; (3) The thermoplastic polyolefin elastomer is selected from polypropylene.

7. The high-voltage cable polypropylene insulation material according to any one of claims 1 to 5, characterized in that, The antioxidant is selected from hindered phenolic antioxidants.

8. A method for preparing the polypropylene insulation material for high-voltage cables according to any one of claims 1 to 7, characterized in that, Includes the following steps: The polypropylene in-reactor alloy, the thermoplastic polyolefin elastomer, and the antioxidant are melt-blended in parts by weight, and then extruded to prepare the high-voltage cable polypropylene insulation material. The melt blending temperature is 150℃~200℃.

9. The method for preparing polypropylene insulation material for high-voltage cables according to claim 8, characterized in that, The melt blending time is 5 min to 15 min.

10. The application of the high-voltage cable polypropylene insulation material according to any one of claims 1 to 7 in high-voltage AC cable insulation materials.

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