High-voltage cable polypropylene insulation material and its preparation method and application

Abstract

In the high-voltage cable polypropylene insulation material provided by the present application, the alloy resin in the polypropylene kettle serves as a composite material skeleton, which can make the high-voltage cable polypropylene insulation material have excellent heat resistance; at the same time, the thermoplastic polyolefin elastomer can induce interface shear bands or silver cracks, thereby enabling the energy of external forces to be dissipated through the shear bands or silver cracks, so that the high-voltage cable polypropylene insulation material can maintain excellent mechanical strength even at high temperatures; and the alloy resin in the polypropylene kettle and the thermoplastic polyolefin elastomer in the present application have good compatibility, 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, and can meet the application conditions of high-voltage cable polypropylene insulation materials.

Description

Technical Field

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

[0002] High-voltage cables, a type of power cable, play a vital role in national power transmission and distribution, as well as in smart grid development. Currently, high-voltage cables primarily use cross-linked polyethylene (XLPE) as their primary insulation material. However, XLPE-insulated cables have poor heat resistance and cannot meet the requirements of larger-capacity power transmission systems. Furthermore, XLPE cables cannot be recycled after their lifespan expires, generating significant amounts of waste and posing a significant environmental challenge.

[0003] Thermoplastic polypropylene (TP) high-voltage cables offer high operating temperatures and are recyclable, making them a new generation of environmentally friendly cables that can replace cross-linked polyethylene (XLPE). However, PP as a cable insulation material lacks both excellent heat resistance and toughness. Summary of the Invention

[0004] Based on this, the present application provides a high-voltage cable polypropylene insulation material and its preparation method and application. The high-voltage cable polypropylene insulation material has both excellent heat resistance and toughness.

[0005] In a first aspect of the present application, a high-voltage cable polypropylene insulation material is provided, wherein the raw materials thereof, in parts by weight, comprise the following components:

[0006] 30 to 60 parts of alloy resin in polypropylene kettle,

[0007] 40 to 70 parts of thermoplastic polyolefin elastomer, and

[0008] 0.3 to 1 part of antioxidant.

[0009] In one embodiment, the alloy resin in the polypropylene kettle includes a rubber phase and homopolypropylene in a mass ratio of 1:(3-4).

[0010] In one embodiment, the isotacticity of the homopolypropylene is ≥95%.

[0011] In one embodiment, the phase size of the rubber phase in the alloy resin in the polypropylene kettle is 0.2-1 μm.

[0012] In one embodiment, the rubber phase is selected from ethylene-propylene random copolymer.

[0013] In one embodiment, the thermoplastic polyolefin elastomer has one or more of the following characteristics:

[0014] (1) The density of the thermoplastic polyolefin elastomer is 0.85 g / cm3 to 0.89 g / cm3;

[0015] (2) The thermoplastic polyolefin elastomer has a melt index of 0.5 g / 10 min to 0.8 g / 10 min at 230° C. and a load of 2.16 kg;

[0016] (3) The thermoplastic polyolefin elastomer is selected from polypropylene.

[0017] In one embodiment, the antioxidant is selected from hindered phenol antioxidants.

[0018] In a second aspect of the present application, there is provided a method for preparing the high-voltage cable polypropylene insulation material according to any one of the embodiments of the first aspect of the present application, comprising the following steps:

[0019] The polypropylene alloy in the autoclave, the thermoplastic polyolefin elastomer and the antioxidant are melt-blended in parts by weight, and the mixture is extruded to prepare the high-voltage cable polypropylene insulation material;

[0020] The temperature of the melt blending is 150°C to 200°C.

[0021] In one embodiment, the melt blending time is 5 minutes to 15 minutes.

[0022] The third aspect of the present application provides a use of the high-voltage cable polypropylene insulation material described in any embodiment of the first aspect of the present application in a high-voltage AC cable insulation material.

[0023] In the high-voltage cable polypropylene insulation material provided by the present application, the alloy resin in the polypropylene kettle serves as a composite material skeleton, which can make the high-voltage cable polypropylene insulation material have excellent heat resistance; at the same time, the thermoplastic polyolefin elastomer can induce interface shear bands or silver cracks, thereby enabling the energy of external forces to be dissipated through the shear bands or silver cracks, so that the high-voltage cable polypropylene insulation material can maintain excellent mechanical strength even at high temperatures; and the alloy resin in the polypropylene kettle and the thermoplastic polyolefin elastomer in the present application have good compatibility, 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, and can meet the application conditions of the high-voltage cable polypropylene insulation material. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a bar graph of the bending modulus of the high-voltage cable polypropylene insulation material prepared in Examples 1 to 4 and Comparative Examples 1 to 2 of the present application;

[0025] Figure 2A histogram of the breakdown field strength of the high-voltage cable polypropylene insulation materials prepared in Examples 1 to 4 and Comparative Examples 1 to 2 of the present application;

[0026] Figure 3 This is a melting temperature curve of the high-voltage cable polypropylene insulation material prepared in Examples 1 to 4 and Comparative Examples 1 to 2 of the present application. DETAILED DESCRIPTION

[0027] The following, in conjunction with specific examples, provides a further complete and clear description of the high-voltage cable polypropylene insulation material and the preparation method and application of the high-voltage cable polypropylene insulation material of the present application. The present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, the purpose of providing these embodiments is to provide a more thorough and comprehensive understanding of the disclosure of the present application.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0029] As used herein, "one or more" refers to any one, any two, or any two or more of the listed items.

[0030] In this application, terms such as "first aspect," "second aspect," "third aspect," "fourth aspect," and "fifth aspect" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or quantity, nor should they be understood as implicitly indicating the importance or quantity of the technical features indicated. Furthermore, terms such as "first," "second," "third," "fourth," and "fifth" serve only as non-exhaustive enumeration and description, and should not constitute a closed-ended limitation on quantity.

[0031] In this application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0032] In this application, when referring to numerical ranges, unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges subsumed therein.

[0033] Unless otherwise specified, the percentage contents mentioned in this application refer to mass percentage for solid-liquid mixture and solid-solid mixture, and refer to volume percentage for liquid-liquid mixture.

[0034] The percentage concentrations mentioned in this application, unless otherwise specified, refer to the final concentration, which refers to the percentage of the added component in the system after the addition of the component.

[0035] The temperature parameters in this application, unless otherwise specified, allow for both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows for temperature fluctuations within the precision range of instrument control.

[0036] In this application, unless otherwise specified, "isotacticity" refers to the mass fraction of stereoregular polymer in the total polymer, and is used to indicate the degree of stereoregularity of isotactic polymer.

[0037] In a first aspect of the present application, a high-voltage cable polypropylene insulation material is provided, wherein the raw materials thereof, in parts by weight, comprise the following components:

[0038] 30 to 60 parts of alloy resin in polypropylene kettle,

[0039] 40 to 70 parts of thermoplastic polyolefin elastomer, and

[0040] 0.3 to 1 part of antioxidant.

[0041] In the high-voltage cable polypropylene insulation material provided by the present application, the alloy resin in the polypropylene kettle serves as a composite material skeleton, which can make the high-voltage cable polypropylene insulation material have excellent heat resistance; at the same time, the thermoplastic polyolefin elastomer can induce interface shear bands or silver cracks, thereby enabling the energy of external forces to be dissipated through the shear bands or silver cracks, so that the high-voltage cable polypropylene insulation material can maintain excellent mechanical strength even at high temperatures; and the alloy resin in the polypropylene kettle and the thermoplastic polyolefin elastomer in the present application have good compatibility, 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, and can meet the application conditions of high-voltage cable polypropylene insulation materials.

[0042] It is understood that the weight percentage of the alloy resin in the polypropylene kettle can be selected from any value between 30 and 60 parts. Specifically, the weight percentage of the alloy resin in the polypropylene kettle includes, but is not limited to, 30, 35, 38, 40, 45, 50, 52, 55, 58, or 60 parts. The weight percentage of the thermoplastic polyolefin elastomer can be selected from any value between 40 and 70 parts. Specifically, the weight percentage of the thermoplastic polyolefin elastomer includes, but is not limited to, 40, 45, 48, 49, 50, 52, 55, 58, 60, 61, 62, 65, or 70 parts. The weight percentage of the antioxidant can be selected from any value between 0.3 and 1 part. Specifically, the weight percentage of the antioxidant includes, but is not limited to, 0.3, 0.5, 0.7, 0.9, or 1 part.

[0043] Preferably, the raw materials of the high-voltage cable polypropylene insulation material include the following components in parts by weight:

[0044] 38 to 52 parts of alloy resin in polypropylene kettle,

[0045] 48 to 62 parts of thermoplastic polyolefin elastomer, and

[0046] 0.3 to 1 part of antioxidant.

[0047] In one example, the alloy resin in the polypropylene kettle includes a rubber phase and homopolypropylene in a mass ratio of 1:(3-4).

[0048] In one example, the homopolypropylene has an isotacticity of ≥95%.

[0049] Traditional polypropylene kettle alloy resin as a high-voltage insulating material has the disadvantages of insufficient toughness, poor electrical properties, low breakdown field strength and poor thermal stability in high-temperature environments. The present application can ensure the regularity of the molecular chain by selecting homopolypropylene with an isotacticity ≥ 95%, and under the cooperation of a certain weight portion of rubber, the polypropylene kettle alloy resin has high crystallinity and large rigidity, and can use the obtained polypropylene kettle alloy resin as a composite material skeleton to improve the temperature resistance of high-voltage cable polypropylene insulation materials. Optionally, the weight portions of homopolypropylene include but are not limited to 80 parts, 82 parts, 85 parts, 90 parts, 93 parts or 95 parts. The weight portions of rubber include but are not limited to 5 parts, 8 parts, 10 parts, 15 parts or 20 parts. The isotacticity of homopolypropylene includes but is not limited to 95%, 96%, 97%, 98% or 99%.

[0050] In one example, the size of the rubber phase in the alloy resin in the polypropylene kettle is 0.2 to 1 μm. By limiting the size of the rubber phase, the influence of the rubber phase on the heat resistance of the alloy resin in the polypropylene kettle can be reduced.

[0051] In one specific example, the rubber phase is selected from ethylene-propylene random copolymer.

[0052] In one example, the density of the thermoplastic polyolefin elastomer is 0.85 g / cm 3 ~0.89g / cm 3 It is understood that the density of the thermoplastic polyolefin elastomer can be selected from 0.85 g / cm 3 ~0.89g / cm 3 Specifically, the density of the thermoplastic polyolefin elastomer includes but is not limited to 0.85 g / cm 3 , 0.86g / cm 3 , 0.87g / cm 3 , 0.88g / cm 3 or 0.89g / cm 3 .

[0053] In one example, the melt index of the thermoplastic polyolefin elastomer at 230°C × 2.16kg load is 0.5g / 10min to 0.8g / 10min. It is understandable that the melt index of the thermoplastic polyolefin elastomer at 230°C × 2.16kg load can be selected from any value between 0.5g / 10min and 0.8g / 10min. Specifically, the melt index of the thermoplastic polyolefin elastomer includes but is not limited to 0.5g / 10min, 0.6g / 10min, 0.7g / 10min or 0.8g / 10min. The density and melt index of the thermoplastic polyolefin elastomer are selected within this range to improve the mechanical toughness of the polypropylene insulation material of the high-voltage cable.

[0054] In one example, the thermoplastic polyolefin elastomer includes 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 a polypropylene elastomer comprising 50-70 parts by weight of ethylene-propylene rubber and 30-50 parts by weight of polypropylene. This ensures the dispersion of the polypropylene and enhances the compatibility of the thermoplastic polyolefin elastomer with the polypropylene in-vessel alloy.

[0055] Antioxidants can prevent aging of polypropylene insulation materials used in high-voltage cables. In one example, the antioxidant is selected from hindered phenolic antioxidants. Examples of antioxidants include pentaerythritol [β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], dilauryl thiodipropionate, and phosphite antioxidants.

[0056] In one example, the flexural modulus of the polypropylene insulation material for high-voltage cables is 100 MPa to 600 MPa. The polypropylene insulation material for high-voltage cables provided herein has a moderate flexural modulus, resulting in excellent toughness. A low flexural modulus would result in insufficient rigidity when used in cables, affecting the cable's long-term creep resistance. A high flexural modulus would result in insufficient toughness for the polypropylene insulation material, failing to meet cable requirements.

[0057] In one example, the load elongation of the polypropylene insulation material of the high-voltage cable is ≤13%.

[0058] In one example, the permanent deformation rate of the polypropylene insulation material of the high-voltage cable is ≤11%.

[0059] The high-voltage cable polypropylene insulation material provided in this application has excellent low modulus, high elasticity and excellent mechanical properties, which greatly reduces the bending modulus of the composite material and gives it excellent toughness.

[0060] In one example, the breakdown field strength of the high-voltage cable polypropylene insulation material is ≥130 MV / m. The high-voltage cable polypropylene insulation material provided in this application has a high breakdown field strength and excellent electrical properties.

[0061] In a second aspect of the present application, there is provided a method for preparing the high-voltage cable polypropylene insulation material according to any example of the first aspect of the present application, comprising the following steps:

[0062] The polypropylene in-reactor alloy, the thermoplastic polyolefin elastomer and the antioxidant are melt-blended according to weight parts, and then extruded to prepare the high-voltage cable polypropylene insulation material.

[0063] In one example, the melt blending temperature is 150° C. to 200° C. It is understood that the melt blending temperature can be selected from any value between 150° C. and 220° C. Specifically, the temperature includes but is not limited to 150° C., 180° C., 190° C., 200° C., 210° C., or 220° C.

[0064] In one example, the melt blending time is 5 min to 15 min. It is understood that the mixing time can be selected from any value between 5 min and 15 min. Specifically, the mixing time includes but is not limited to 5 min, 8 min, 12 min, 13 min or 15 min.

[0065] In one example, the mixing process parameters include: the rotation speed is set to 80 r / min to 180 r / min. It is understandable that the rotation speed can be set to any value between 80 r / min and 180 r / min. Specifically, the rotation speed value 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. Setting the mixing process parameters can enhance the dispersibility and compatibility between the various components of the high-voltage cable polypropylene insulation material.

[0066] A third aspect of the present application provides a use of the polypropylene insulation material for high-voltage cables described in any example of the present application in a high-voltage AC cable insulation material. The polypropylene insulation material for high-voltage cables provided in the present application has a wide range of applications. For example, the polypropylene insulation material for high-voltage cables can be used in 110 kV high-voltage AC cables.

[0067] The following are specific examples. Unless otherwise specified, the raw materials used in the examples are all commercially available products.

[0068] Example 1

[0069] Weigh 60 parts of polypropylene-based alloy resin in the kettle (the mass ratio of rubber phase to homopolymer polypropylene is 1:4; the isotacticity of homopolymer polypropylene is ≥95%; the rubber phase size is 0.2-1.0 μm, and the rubber phase is ethylene-propylene random copolymer), 40 parts of thermoplastic polypropylene elastomer (density 0.89 g / cm 3 , a melt index (230°C x 2.16 kg) of 0.8 g / 10 min), and 0.3 parts of an antioxidant (hindered phenolic antioxidant 1010, commercially available) were melt blended and extruded in an internal mixer to obtain a high-voltage cable polypropylene insulation material. The melt blending process was as follows: temperature 200°C, time 15 minutes, and rotation speed 90 r / min.

[0070] Example 2

[0071] Weigh 50 parts of polypropylene-based alloy resin in the kettle (the mass ratio of rubber phase to homopolymer polypropylene is 1:4; the isotacticity of homopolymer polypropylene is ≥95%; the rubber phase size is 0.2-1.0 μm, and the rubber phase is ethylene-propylene random copolymer), 50 parts of thermoplastic polypropylene elastomer (density 0.89 g / cm 3 , a melt index (230°C x 2.16 kg) of 0.8 g / 10 min), and 0.3 parts of an antioxidant (hindered phenolic antioxidant 1010, commercially available) were melt blended and extruded in an internal mixer to obtain a high-voltage cable polypropylene insulation material. The melt blending process was as follows: temperature 200°C, time 15 minutes, and rotation speed 90 r / min.

[0072] Example 3

[0073] Weigh 40 parts of polypropylene-based alloy resin in the kettle (the mass ratio of rubber phase to homopolymer polypropylene is 1:4; the isotacticity of homopolymer polypropylene is ≥95%; the rubber phase size is 0.2-1.0 μm, and the rubber phase is ethylene-propylene random copolymer), 60 parts of thermoplastic polypropylene elastomer (density 0.89 g / cm 3 , a melt index (230°C x 2.16 kg) of 0.8 g / 10 min), and 0.3 parts of an antioxidant (hindered phenolic antioxidant 1010, commercially available) were melt blended and extruded in an internal mixer to obtain a high-voltage cable polypropylene insulation material. The melt blending process was as follows: temperature 200°C, time 15 minutes, and rotation speed 90 r / min.

[0074] Example 4

[0075] Weigh 30 parts of polypropylene-based alloy resin in the kettle (the mass ratio of rubber phase to homopolymer polypropylene is 1:4; the isotacticity of homopolymer polypropylene is ≥95%; the rubber phase size is 0.2-1.0 μm, and the rubber phase is ethylene-propylene random copolymer), 70 parts of thermoplastic polypropylene elastomer (density 0.89 g / cm 3 , a melt index (230°C x 2.16 kg) of 0.8 g / 10 min), and 0.3 parts of an antioxidant (hindered phenolic antioxidant 1010, commercially available) were melt blended and extruded in an internal mixer to obtain a high-voltage cable polypropylene insulation material. The melt blending process was as follows: temperature 200°C, time 15 minutes, and rotation speed 90 r / min.

[0076] Example 5

[0077] Weigh 30 parts of polypropylene-based alloy resin in the kettle (the mass ratio of rubber phase to homopolymer polypropylene is 1:3; the isotacticity of homopolymer polypropylene is ≥95%; the rubber phase size is 0.2-1.0 μm, and the rubber phase is ethylene-propylene random copolymer), 70 parts of thermoplastic polypropylene elastomer (density 0.85 g / cm 3 , a melt index (230°C x 2.16 kg) of 0.5 g / 10 min), and 1 part antioxidant were placed in an internal mixer for melt blending and extrusion to obtain a high-voltage cable polypropylene insulation material. The melt blending process was as follows: temperature 150°C, time 5 minutes, and rotation speed 90 r / min.

[0078] Comparative Example 1

[0079] Weigh 70 parts of polypropylene alloy resin in the kettle (the mass ratio of rubber phase to homopolymer polypropylene is 1:4; the isotacticity of homopolymer polypropylene is ≥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 (density 0.89 g / cm 3 , a melt index (230°C x 2.16 kg) of 0.8 g / 10 min), and 0.3 parts of an antioxidant (hindered phenolic antioxidant 1010, commercially available) were melt blended and extruded in an internal mixer to obtain a high-voltage cable polypropylene insulation material. The melt blending process was as follows: a temperature of 200°C, a time of 15 minutes, and a rotation speed of 90 r / min.

[0080] Comparative Example 2

[0081] Weigh 20 parts of polypropylene alloy resin in the kettle (the mass ratio of rubber phase to homopolymer polypropylene is 1:4; the isotacticity of homopolymer polypropylene is ≥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 (density 0.89 g / cm 3 , a melt index (230°C x 2.16 kg) of 0.8 g / 10 min), and 0.3 parts of an antioxidant (hindered phenolic antioxidant 1010, commercially available) were melt blended and extruded in an internal mixer to obtain a high-voltage cable polypropylene insulation material. The melt blending process was as follows: temperature 200°C, time 15 minutes, and rotation speed 90 r / min.

[0082] Comparative Example 3

[0083] 100 parts of polypropylene-based in-autoclave alloy resin (rubber phase to homopolypropylene mass ratio of 1:4; homopolypropylene isotacticity ≥ 95%; rubber phase size 0.2-1.0 μm, ethylene-propylene random copolymer) and 0.3 parts of antioxidant (hindered phenol antioxidant 1010, commercially available) were weighed as raw materials, melt blended, and extruded in an internal mixer to produce a high-voltage cable polypropylene insulation material. The melt blending process was as follows: temperature 200°C, time 15 minutes, and rotation speed 90 rpm.

[0084] Comparative Example 4

[0085] 100 parts of homopolypropylene and 0.3 parts of an antioxidant (hindered phenolic antioxidant 1010, commercially available) were weighed as raw materials, melt blended, and extruded in an internal mixer to obtain a high-voltage cable polypropylene insulation material. The melt blending process was as follows: temperature 200°C, time 15 minutes, and rotation speed 90 rpm.

[0086] The flexural modulus, crystal structure and heat resistance of the high-voltage cable polypropylene insulation materials prepared in the examples and comparative examples were characterized and tested.

[0087] The test method or standard is:

[0088] (1) Flexural modulus: tested based on GB / T9341-2008;

[0089] (2) Electrical performance: tested based on GB / T 1408.1-2016;

[0090] (3) Crystal structure: Characterization was performed using a differential scanning calorimeter (TA Q250). About 5 mg of the sample was placed in an open crucible and heated from room temperature to 200 °C at a heating rate of 10 °C / min under a nitrogen atmosphere. The change in heat flow signal with temperature was recorded.

[0091] (4) Heat resistance test: To evaluate whether the insulating material can maintain the necessary mechanical strength under the expected overload temperature, prepare the specimen according to the tensile performance test method. Use the standard test method of the thermal extension test. Hang one end of the specimen in an oven set to 150°C. Place a weight on the other end that applies a tensile force of 0.2 MPa to the specimen cross section. After a set time of 15 minutes, measure the elongation of the specimen, which is defined as the elongation under load. The elongation after cooling is defined as the permanent set rate.

[0092] The test results are shown in Table 1:

[0093] Table 1

[0094]

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

[0096] Although the polypropylene insulation material prepared in Comparative Example 1 exhibited low elongation and permanent deformation under high temperature, its flexural modulus was too high (>600 MPa) and the material's toughness was insufficient, failing to meet cable requirements. The flexural modulus of the polypropylene insulation material prepared in Comparative Example 2 was slightly lower, resulting in slightly weaker rigidity. Furthermore, the polypropylene insulation material prepared in Comparative Example 2 exhibited poor heat resistance. During testing, the sample's deformation under load was excessive, reaching the bottom of the oven, preventing accurate values ​​from being obtained. The polypropylene insulation materials prepared in Comparative Examples 3 and 4 both suffered from excessively high flexural moduli, resulting in easy deformation and insufficient toughness, making them unsuitable for practical use.

[0097] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0098] The embodiments described above only express several implementation methods of the present application, which are convenient for understanding the technical solutions of the present application in a specific and detailed manner, but they cannot be understood as limiting the scope of protection of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several variations and improvements can be made, which all fall within the scope of protection of the present application. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided in the present application are all within the scope of protection of the claims attached to the present application. Therefore, the scope of protection of the patent of this application shall be based on the content of the attached claims, and the description can be used to interpret the content of the claims.

Claims

1. A polypropylene insulation material for high-voltage cables, characterized in that: The raw materials include the following components in parts by weight: 30 to 60 parts of alloy resin in polypropylene kettle, 40 to 70 parts of thermoplastic polyolefin elastomer, and 0.3 to 1 part of antioxidant; The alloy resin in the polypropylene kettle comprises a rubber phase and homopolypropylene in a mass ratio of 1:(3-4); the isotacticity of the homopolypropylene is ≥95%; The thermoplastic polyolefin elastomer is polypropylene.

2. The high-voltage cable polypropylene insulation material according to claim 1, characterized in that: The phase size of the rubber phase in the alloy resin in the polypropylene kettle is 0.2-1 μm.

3. The high-voltage cable polypropylene insulation material according to claim 1, characterized in that: The rubber phase is selected from ethylene-propylene random copolymer.

4. The high-voltage cable polypropylene insulation material according to any one of claims 1 to 3, characterized in that: The density of the thermoplastic polyolefin elastomer is 0.85 g / cm 3 ~0.89g / cm 3 .

5. The high-voltage cable polypropylene insulation material according to any one of claims 1 to 3, characterized in that: The thermoplastic polyolefin elastomer has a melt index of 0.5 g / 10 min to 0.8 g / 10 min at 230° C. and a load of 2.16 kg.

6. The high-voltage cable polypropylene insulation material according to any one of claims 1 to 3, characterized in that: The antioxidant is selected from hindered phenol antioxidants.

7. The high-voltage cable polypropylene insulation material according to any one of claims 1 to 3, characterized in that: The bending modulus of the polypropylene insulation material of the high-voltage cable is 100 MPa to 600 MPa; and / or, the load elongation of the polypropylene insulation material of the high-voltage cable is ≤13%; And / or, the permanent deformation rate of the polypropylene insulation material of the high-voltage cable is ≤11%; And / or, the breakdown field strength of the polypropylene insulation material of the high-voltage cable is ≥130MV / m.

8. A method for preparing a high-voltage cable polypropylene insulation material according to any one of claims 1 to 7, characterized in that: The following steps are involved: The polypropylene alloy in the autoclave, the thermoplastic polyolefin elastomer and the antioxidant are melt-blended in parts by weight, and the mixture is extruded to prepare the high-voltage cable polypropylene insulation material; The temperature of the melt blending is 150°C to 200°C.

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

10. Use 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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