Polypropylene-based semiconductive shielding material and preparation method thereof

Abstract

The invention relates to a polypropylene-based semiconductive shielding material and a preparation method thereof, and belongs to the technical field of cable materials. The polypropylene-based semiconductive shielding material provided by the invention is prepared from the following raw materials in parts by weight: 60 to 70 parts of polypropylene, 30 to 40 parts of polar monomer grafted elastomer, 5 to 10 parts of polar monomer grafted polypropylene, 30 to 50 parts of conductive carbon black, 0.5 to 3 parts of lubricant, 0.2 to 0.4 part of initiator, 0.05 to 2 parts of copper inhibitor and 0.1 to 2 parts of antioxidant. The polar monomer grafted elastomer and the polar monomer grafted polypropylene are introduced, the compatibility among the polypropylene resin, the polar monomer grafted elastomer and the conductive carbon black is improved through the chemical coupling effect among polar monomers, and the phenomena of agglomeration and stress concentration of the conductive carbon black are slowed down; therefore, the electrical performance and the mechanical performance of the polypropylene-based semi-conductive shielding material can be improved at the same time.

Description

Technical Field

[0001] The invention belongs to the technical field of cable materials, and particularly relates to a polypropylene-based semi-conductive shielding material and a preparation method thereof. Background Art

[0002] A semiconductive shielding layer, a specialized material located between the conductor and insulator, is a crucial component of high-voltage AC and DC cables. It eliminates defects at the interface between the cable insulation and the conductor / metal shield, creates a uniform electric field, and prevents partial discharge between the conductor and insulation caused by uneven conductor surfaces and air gaps created by twisted wires. Semiconductive shielding materials typically consist of a base resin, conductive fillers, crosslinkers, antioxidants, and other processing aids. These layers are formed through extrusion. The research and development of composite semiconductive shielding materials has become both a hot topic and a challenge.

[0003] In recent years, due to the advantages of polypropylene (PP) such as recyclability, high temperature resistance, and the lack of cross-linking during the extrusion process, the research and development of PP-based insulating cable materials has been in full swing. Therefore, the development of complementary non-cross-linked PP-based semi-conductive shielding materials is also imperative. The production of semi-conductive shielding materials requires the addition of conductive carbon black as a conductive material. However, the presence of a large number of polar groups such as hydroxyl, amino, and carboxyl groups on the surface of conductive carbon black, while polypropylene resin is non-polar, leads to poor compatibility between the two, resulting in conductive carbon black agglomeration and stress concentration, which significantly reduces the mechanical and electrical properties of PP-based semi-conductive shielding materials.

[0004] Therefore, how to improve the compatibility of polypropylene resin and conductive carbon black has become the focus of research. Summary of the Invention

[0005] The purpose of the present invention is to overcome the problems existing in the above-mentioned prior art and provide a polypropylene-based semi-conductive shielding material and a preparation method thereof.

[0006] The present invention is achieved through the following technical solutions:

[0007] In the first aspect, the present invention provides a polypropylene-based semiconductive shielding material, which includes the following raw materials, by weight: 60 to 70 parts of polypropylene, 30 to 40 parts of polar monomer grafted elastomer, 5 to 10 parts of polar monomer grafted polypropylene, 30 to 50 parts of conductive carbon black, 0.5 to 3 parts of lubricant, 0.2 to 0.4 parts of initiator, 0.05 to 2 parts of anti-copper agent, 0.1 to 2 parts of antioxidant, and 0 to 16 parts of radiation protection agent.

[0008] The polypropylene-based semiconductive shielding material of the present invention introduces an elastomer grafted with a polar monomer and polypropylene grafted with a polar monomer. Through the chemical coupling between the polar monomers, the compatibility between the polypropylene resin and the elastomer grafted with the polar monomer and the conductive carbon black is improved, and the agglomeration of the conductive carbon black and the stress concentration phenomenon are slowed down, thereby simultaneously improving the electrical and mechanical properties of the polypropylene-based semiconductive shielding material.

[0009] Preferably, the polypropylene has a melting point of no more than 130° C. and a melt index of no more than 4 g / 10 min.

[0010] The present invention does not limit the type of polypropylene, and can select homopolymer polypropylene, copolymer polypropylene, or a mixture of the two. The melt index can be tested using a melt flow rate tester.

[0011] Preferably, the polar monomer includes at least one of maleic anhydride and styrene.

[0012] Preferably, the polar monomer grafted elastomer is at least one of styrene grafted polyolefin elastomer (POE-g-St), maleic anhydride grafted polyolefin elastomer (POE-g-MAH), styrene grafted styrene-butadiene-styrene block copolymer (SEBS-g-St), and maleic anhydride grafted styrene-butadiene-styrene block copolymer (SEBS-g-MAH).

[0013] Preferably, the polar monomer grafted elastomer is at least one of styrene grafted styrene-butadiene-styrene block copolymer (SEBS-g-St) and maleic anhydride grafted styrene-butadiene-styrene block copolymer (SEBS-g-MAH).

[0014] Studies have shown that SEBS grafted with polar monomers has better mechanical and conductive properties than POE grafted with polar monomers.

[0015] Preferably, the grafting rate of the polar monomer in the polar monomer grafted elastomer is 10% to 15%.

[0016] Preferably, the polar monomer grafted polypropylene is at least one of styrene grafted polypropylene (PP-g-St) and maleic anhydride grafted polypropylene (PP-g-MAH).

[0017] Preferably, the grafting rate of the polar monomer in the polar monomer grafted polypropylene is 2% to 5%; more specifically, the grafting rate of the polar monomer in the polar monomer grafted polypropylene is 2% to 5%, and is not 5%.

[0018] Specifically, the grafting rate is measured by comparing the weight change of the polypropylene or elastomer before and after grafting, and calculating the mass fraction of the grafted monomer based on the excess mass. This test method is subject to error, and the grafting rate is generally a range value.

[0019] Furthermore, the present invention selects polar monomer grafted polypropylene with a polar monomer grafting rate of 2% to 5% as a compatibilizer, and better forms a gradient transition between the elastomer grafted with a polar monomer with a polar monomer grafting rate of 10% to 15% and the polypropylene matrix. The polar monomer is grafted onto the polypropylene and the elastomer, and at the same time chemically couples with the polar groups on the surface of the conductive carbon black to form macromolecular flexible chain segments that are entangled with each other, thereby better ensuring the mechanical properties of the polypropylene-based insulating material.

[0020] Preferably, the polar monomer grafted elastomer is composed of SEBS-g-St and SEBS-g-MAH in a weight ratio of (2-3):1.

[0021] Preferably, the polar monomer grafted polypropylene consists of PP-g-St and PP-g-MAH in a weight ratio of 1:(1-2).

[0022] Specifically, the polar monomer grafted elastomer is obtained by melt-kneading the polar monomer and the elastomer under the action of an initiator; the amount of the polar monomer added is 2% to 5% of the mass of the elastomer.

[0023] Specifically, the polar monomer grafted polypropylene is obtained by melt-mixing the polar monomer and polypropylene under the action of an initiator; the added amount of the polar monomer is 10% to 15% of the mass of the polypropylene.

[0024] Preferably, the conductive carbon black has an iodine absorption value of ≥160 g / kg and an oil absorption value of ≥130 mL / 100 g.

[0025] Preferably, the initiator comprises at least one of dilauroyl peroxide, dicyclohexyl peroxydicarbonate, cumene hydroperoxide and dicumyl peroxide.

[0026] Preferably, the anti-copper agent includes at least one of bis(3,5-di-tert-butyl-4-hydroxy-phenylpropionyl)hydrazine (antioxidant MD-1024) and 2,2-oxalamido-bis[ethyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)]propionate (antioxidant MD-697).

[0027] Preferably, the antioxidant includes at least one of a hindered phenol antioxidant and a phosphite antioxidant.

[0028] Preferably, the lubricant includes at least one of polypropylene wax, polyethylene wax, and microcrystalline wax.

[0029] Preferably, the polypropylene-based semi-conductive shielding material further comprises 0 to 16 parts of a radiation protection agent.

[0030] The material of the present invention may or may not be added with a radiation protection agent as required. If added, the anti-copper agent may optionally include at least one of Bi2O3, Bi2WO6, and titanium dioxide.

[0031] In a second aspect, the present invention provides a method for preparing the polypropylene-based semi-conductive shielding material, comprising the following steps: high-temperature melt mixing of 90 wt% to 95 wt% of polypropylene with a polar monomer grafted elastomer, a polar monomer grafted polypropylene, and an initiator, adding conductive carbon black, high-temperature melt mixing, and then adding the remaining polypropylene, antioxidant, anti-copper agent, and lubricant, continuing high-temperature melt mixing, and extruding and granulating to obtain the polypropylene-based semi-conductive shielding material.

[0032] The preparation method of the polypropylene-based semi-conductive shielding material of the present invention is simple and applicable to industrial production.

[0033] Preferably, the high-temperature melt mixing is carried out at a temperature of 170° C. to 180° C., and for a time of 2 min to 10 min.

[0034] Preferably, the high-temperature melt mixing is carried out in an internal mixer or a torque rheometer; and the granulation is carried out by extrusion through a twin-screw extruder.

[0035] The present invention has the following beneficial effects: by introducing polar monomer-grafted elastomers and polar monomer-grafted polypropylene, the present invention improves the compatibility between polypropylene resin and the polar monomer-grafted elastomer and conductive carbon black, thereby being able to simultaneously improve the electrical and mechanical properties of polypropylene-based semiconductive shielding materials. DETAILED DESCRIPTION

[0036] To better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. Those skilled in the art should understand that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0037] Unless otherwise specified, the experimental methods used in the examples are conventional methods; the materials, reagents, etc. used are all available from commercial sources unless otherwise specified.

[0038] In the preparation methods of the polypropylene-based semi-conductive shielding materials of the following examples and comparative examples, an internal mixer is used for high-temperature melting and a twin-screw extruder is used for granulation.

[0039] In the polypropylene-based semiconductive shielding materials of the following examples and comparative examples,

[0040] The polypropylene has a melt index of 1.9 g / 10 min and is commercially available;

[0041] The conductive carbon black has an oil absorption value of 174 mL / 100 g and an iodine absorption value of 253 g / kg, and is manufactured by CABOT. XC72;

[0042] The grafting rate of the SEBS-g-St is 2% to 5%. The preparation method comprises: uniformly mixing SEBS, styrene, an initiator, and an antioxidant in a certain mass ratio, pouring the mixture into a twin-screw mixer, setting the mixing temperature to 190°C, adjusting the screw speed, and controlling the reaction time of the entire grafting reaction (the time from feeding to discharging) to be approximately 40 seconds. After the reaction is completed, the mixture is extruded through a multi-hole die, cooled by water, and pelletized by a pelletizer. (Formulation ratio: SEBS 100 parts, styrene 5 parts, initiator 0.2 parts, antioxidant 1010 0.1 parts, antioxidant 168 0.1 parts)

[0043] The grafting rate of the SEBS-g-MAH is 2% to 5%. The preparation method comprises: uniformly mixing SEBS, maleic anhydride, an initiator, and an antioxidant in a certain mass ratio, pouring the mixture into a twin-screw mixer, setting the mixing temperature to 190°C, adjusting the screw speed, and controlling the reaction time of the entire grafting reaction (the time from feeding to discharging) to be approximately 40 seconds. After the reaction is completed, the mixture is extruded through a multi-hole die, cooled in water, and pelletized by a pelletizer. (Formulation ratio: SEBS 100 parts, maleic anhydride 5 parts, initiator 0.2 parts, antioxidant 1010 0.1 parts, antioxidant 168 0.1 parts)

[0044] The grafting rate of the PP-g-St is 10% to 15%. The preparation method comprises: uniformly mixing PP, styrene, an initiator, and an antioxidant in a certain mass ratio, pouring the mixture into a twin-screw mixer, setting the mixing temperature to 190°C, adjusting the screw speed, and controlling the reaction time of the entire grafting reaction (the time from feeding to discharging) to be approximately 40 seconds. After the reaction is completed, the mixture is extruded through a multi-hole die, cooled by water, and pelletized by a pelletizer. (Formulation ratio: 100 parts PP, 15 parts styrene, 0.4 parts initiator, 0.1 parts antioxidant 1010, and 0.1 parts antioxidant 168)

[0045] The grafting rate of the PP-g-MAH is 10% to 15%. The preparation method comprises: uniformly mixing PP, maleic anhydride, an initiator, and an antioxidant in a certain mass ratio, pouring the mixture into a twin-screw mixer, setting the mixing temperature to 190°C, adjusting the screw speed, and controlling the reaction time of the entire grafting reaction (the time from feeding to discharging) to be approximately 40 seconds. After the reaction is completed, the mixture is extruded through a multi-hole die, cooled by water, and pelletized by a pelletizer. (Formulation ratio: 100 parts PP, 15 parts maleic anhydride, 0.4 parts initiator, 0.1 parts antioxidant 1010, and 0.1 parts antioxidant 168)

[0046] Unless otherwise specified, the components and raw materials used in the examples and comparative examples of the present invention are all commercially available raw materials, and the components and raw materials used in each parallel experiment are all of the same kind.

[0047] Example 1

[0048] A polypropylene-based semiconductive shielding material comprises the following raw materials, calculated by weight: 65 parts of polypropylene, 24 parts of SEBS-g-St, 8 parts of SEBS-g-MAH, 4 parts of PP-g-St, 4 parts of PP-g-MAH, 45 parts of conductive carbon black, 2 parts of polypropylene wax, 0.3 parts of dicyclohexyl peroxydicarbonate, 0.8 parts of antioxidant MD1024, and 0.4 parts of antioxidant 1010.

[0049] The method for preparing the polypropylene-based semiconductive shielding material described in this embodiment comprises the following steps:

[0050] 95 wt% of polypropylene was melt-mixed with SEBS-g-St, SEBS-g-MAH, PP-g-St, PP-g-MAH and dicyclohexyl peroxydicarbonate at 175°C for 5 minutes, and conductive carbon black was added and melt-mixed at high temperature for 8 minutes. Then, the remaining polypropylene, antioxidant 1010, antioxidant MD1024 and polypropylene wax were added and melt-mixed at high temperature for 8 minutes. The mixture was extruded and granulated to obtain the polypropylene-based semi-conductive shielding material of this embodiment.

[0051] Example 2

[0052] A polypropylene-based semiconductive shielding material comprises the following raw materials, calculated by weight: 65 parts of polypropylene, 22 parts of POE-g-St, 10 parts of POE-g-MAH, 2.5 parts of PP-g-St, 5 parts of PP-g-MAH, 45 parts of conductive carbon black, 2 parts of polypropylene wax, 0.3 parts of dicyclohexyl peroxydicarbonate, 0.8 parts of antioxidant MD-1024, and 0.4 parts of antioxidant 1010.

[0053] The method for preparing the polypropylene-based semiconductive shielding material described in this embodiment comprises the following steps:

[0054] 95 wt% of polypropylene was melt-mixed with POE-g-St, POE-g-MAH, PP-g-St, PP-g-MAH and dicyclohexyl peroxydicarbonate at 175°C for 5 minutes, and conductive carbon black was added and melt-mixed at high temperature for 8 minutes. Then, the remaining polypropylene, antioxidant 1010, antioxidant MD-1024 and polypropylene wax were added and melt-mixed at high temperature for 8 minutes. The mixture was extruded and granulated to obtain the polypropylene-based semi-conductive shielding material of this embodiment.

[0055] Example 3

[0056] A polypropylene-based semiconductive shielding material comprises the following raw materials, calculated by weight: 65 parts of polypropylene, 32 parts of SEBS-g-St, 8 parts of PP-g-St, 45 parts of conductive carbon black, 2 parts of polypropylene wax, 0.3 parts of dicumyl peroxide, 0.8 parts of antioxidant MD-1024, and 0.4 parts of antioxidant 1010.

[0057] The method for preparing the polypropylene-based semiconductive shielding material described in this embodiment comprises the following steps:

[0058] 95 wt% of polypropylene was melt-mixed with SEBS-g-St, PP-g-St and dicumyl peroxide at 175°C for 5 minutes, and conductive carbon black was added and melt-mixed at high temperature for 8 minutes. Then, the remaining polypropylene, antioxidant 1010, antioxidant MD-1024 and polypropylene wax were added and melt-mixed at high temperature for 8 minutes. The mixture was extruded and granulated to obtain the polypropylene-based semi-conductive shielding material of this embodiment.

[0059] Example 4

[0060] A polypropylene-based semiconductive shielding material comprises the following raw materials, calculated by weight: 65 parts of polypropylene, 32 parts of SEBS-g-MAH, 8 parts of PP-g-MAH, 45 parts of conductive carbon black, 2 parts of polypropylene wax, 0.3 parts of dicumyl peroxide, 0.8 parts of antioxidant MD1024, and 0.4 parts of antioxidant 1010.

[0061] The method for preparing the polypropylene-based semiconductive shielding material described in this embodiment comprises the following steps:

[0062] 95 wt% of polypropylene was melt-mixed with SEBS-g-MAH, PP-g-MAH, and dicumyl peroxide at 175°C for 5 minutes, and conductive carbon black was added and melt-mixed at high temperature for 8 minutes. Then, the remaining polypropylene, antioxidant 1010, antioxidant MD-1024, and polypropylene wax were added and melt-mixed at high temperature for 8 minutes. The mixture was extruded and granulated to obtain the polypropylene-based semi-conductive shielding material of this embodiment.

[0063] Example 5

[0064] A polypropylene-based semiconductive shielding material comprises the following raw materials, calculated by weight: 67 parts of polypropylene, 32 parts of POE-g-St, 7.5 parts of PP-g-St, 47 parts of conductive carbon black, 2 parts of polypropylene wax, 0.3 parts of dicyclohexyl peroxydicarbonate, 0.8 parts of antioxidant MD1024, and 0.4 parts of antioxidant 1010.

[0065] The method for preparing the polypropylene-based semiconductive shielding material described in this embodiment comprises the following steps:

[0066] 95 wt% of polypropylene was melt-mixed with POE-g-St, PP-g-St and dicyclohexyl peroxydicarbonate at 180°C for 4 minutes, and conductive carbon black was added and melt-mixed at high temperature for 10 minutes. Then, the remaining polypropylene, antioxidant 1010, antioxidant MD-1024 and polypropylene wax were added and melt-mixed at high temperature for 5 minutes. The mixture was extruded and granulated to obtain the polypropylene-based semi-conductive shielding material of this embodiment.

[0067] Example 6

[0068] A polypropylene-based semiconductive shielding material comprises the following raw materials, calculated by weight: 67 parts of polypropylene, 32 parts of POE-g-MAH, 7.5 parts of PP-g-MAH, 47 parts of conductive carbon black, 2 parts of polypropylene wax, 0.3 parts of dicyclohexyl peroxydicarbonate, 0.8 parts of antioxidant MD1024, and 0.4 parts of antioxidant 1010.

[0069] The method for preparing the polypropylene-based semiconductive shielding material described in this embodiment comprises the following steps:

[0070] 95 wt% of polypropylene was melt-mixed with POE-g-MAH, PP-g-MAH and dicyclohexyl peroxydicarbonate at 180°C for 4 minutes, and conductive carbon black was added. The mixture was melt-mixed at high temperature for 10 minutes. Then, the remaining polypropylene, antioxidant 1010, antioxidant MD-1024 and polypropylene wax were added. The mixture was melt-mixed at high temperature for 8 minutes and extruded into granules to obtain the polypropylene-based semi-conductive shielding material of this embodiment.

[0071] Example 7

[0072] A polypropylene-based semiconductive shielding material comprises the following raw materials, calculated by weight: 65 parts of polypropylene, 24 parts of SEBS-g-St, 8 parts of SEBS-g-MAH, 4 parts of PP-g-St, 4 parts of PP-g-MAH, 45 parts of conductive carbon black, 2 parts of polypropylene wax, 0.3 parts of dicyclohexyl peroxydicarbonate, 0.8 parts of antioxidant MD1024, and 0.4 parts of antioxidant 1010.

[0073] The method for preparing the polypropylene-based semiconductive shielding material of this embodiment comprises the following steps: melting all the above raw materials together at a high temperature of 180° C. for 21 minutes to obtain the polypropylene-based semiconductive shielding material of this embodiment.

[0074] Comparative Example 1

[0075] A polypropylene-based semiconductive shielding material comprises the following raw materials, calculated by weight: 65 parts of polypropylene, 24 parts of SEBS-g-St, 8 parts of SEBS-g-MAH, 43 parts of conductive carbon black, 2 parts of polypropylene wax, 0.3 parts of dicyclohexyl peroxydicarbonate, 0.8 parts of antioxidant MD1024, and 0.4 parts of antioxidant 1010.

[0076] The preparation method of the polypropylene-based semiconductive shielding material described in this comparative example comprises the following steps:

[0077] 95 wt% of polypropylene was melt-mixed with SEBS-g-St, SEBS-g-MAH and dicyclohexyl peroxydicarbonate at 175°C for 5 minutes, and conductive carbon black was added and melt-mixed at high temperature for 8 minutes. Then, the remaining polypropylene, antioxidant 1010, antioxidant MD1024 and polypropylene wax were added and melt-mixed at high temperature for 8 minutes. The mixture was extruded and granulated to obtain the polypropylene-based semi-conductive shielding material of this comparative example.

[0078] Comparative Example 2

[0079] A polypropylene-based semiconductive shielding material comprises the following raw materials, calculated by weight: 65 parts of polypropylene, 32 parts of SEBS-g-MAH, 43 parts of conductive carbon black, 2 parts of polypropylene wax, 0.3 parts of dicyclohexyl peroxydicarbonate, 0.8 parts of antioxidant MD-1024, and 0.4 parts of antioxidant 1010.

[0080] The preparation method of the polypropylene-based semiconductive shielding material described in this comparative example comprises the following steps:

[0081] 95 wt% of polypropylene was melt-mixed with SEBS-g-MAH and dicyclohexyl peroxydicarbonate at 175°C for 5 minutes, and conductive carbon black was added and melt-mixed at high temperature for 8 minutes. Then, the remaining polypropylene, antioxidant 1010, antioxidant MD-1024 and polypropylene wax were added and melt-mixed at high temperature for 8 minutes. The mixture was extruded and granulated to obtain the polypropylene-based semi-conductive shielding material of this comparative example.

[0082] Comparative Example 3

[0083] A polypropylene-based semiconductive shielding material comprises the following raw materials, calculated by weight: 67.9 parts of polypropylene, 32 parts of POE-g-MAH, 43 parts of conductive carbon black, 2 parts of polypropylene wax, 0.3 parts of dicumyl peroxide, 0.8 parts of antioxidant MD-1024, and 0.4 parts of antioxidant 1010.

[0084] The preparation method of the polypropylene-based semiconductive shielding material described in this comparative example comprises the following steps:

[0085] 95 wt% of polypropylene was melt-mixed with POE-g-MAH and diisopropylbenzene peroxide at 175°C for 5 minutes, and conductive carbon black was added and melt-mixed at high temperature for 8 minutes. Then, the remaining polypropylene, antioxidant 1010, antioxidant MD-1024 and polypropylene wax were added and melt-mixed at high temperature for 8 minutes. The mixture was extruded and granulated to obtain the polypropylene-based semi-conductive shielding material of this comparative example.

[0086] Comparative Example 4

[0087] A polypropylene-based semiconductive shielding material comprises the following raw materials, calculated by weight: 65 parts of polypropylene, 32 parts of SEBS, 4 parts of PP-g-St, 4 parts of PP-g-MAH, 45 parts of conductive carbon black, 2 parts of polypropylene wax, 0.3 parts of dicyclohexyl peroxydicarbonate, 0.8 parts of antioxidant MD1024, and 0.4 parts of antioxidant 1010.

[0088] The preparation method of the polypropylene-based semi-conductive shielding material in this comparative example is the same as that in Example 1, to obtain the polypropylene-based semi-conductive shielding material in this comparative example.

[0089] Performance Testing

[0090] The polypropylene-based semiconductive shielding materials obtained in the examples and comparative examples were subjected to performance tests. The performance test methods are as follows:

[0091] 1. Tensile strength: Determine the tensile strength of the sample in accordance with the provisions of GB / T 1040.2-2006;

[0092] 2. Elongation at break: Refer to the provisions of GB / T 1040-2006 to test the elongation at break of the specimen;

[0093] 3. DC volume resistivity (room temperature), DC volume resistivity (105°C): refer to the provisions of JB / T 10738-2007 to test the DC volume resistivity of the sample;

[0094] 4. Melt flow rate: Melt flow rate was tested according to ASTM D1238-04 (210°C*2.16kg).

[0095] The test results are shown in Table 1.

[0096] Table 1 Performance test results of polypropylene-based semiconductive shielding materials obtained in Examples and Comparative Examples

[0097]

[0098] It can be seen from Table 1 that the polypropylene-based semiconductive shielding material obtained in the embodiment of the present invention has excellent electrical conductivity and mechanical properties.

[0099] The polypropylene-based semiconductive shielding materials of the present invention exhibit higher tensile strength and elongation at break than the polypropylene-based semiconductive shielding materials of Comparative Examples 1-4, and exhibit superior electrical conductivity at room temperature and 105°C. Comparative Examples 1-3 demonstrate that the absence of polar monomer graft modification in polypropylene leads to decreased mechanical properties, increased volume resistivity, and poor processing performance. Comparative Example 4 demonstrates that the addition of an elastomer without polar monomer modification also results in decreased mechanical properties, increased volume resistivity, and poor processing performance.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A polypropylene-based semiconductive shielding material, characterized in that: The raw materials include, by weight: 60-70 parts of polypropylene, 30-40 parts of polar monomer grafted elastomer, 5-10 parts of polar monomer grafted polypropylene, 30-50 parts of conductive carbon black, 0.5-3 parts of lubricant, 0.2-0.4 parts of initiator, 0.05-2 parts of anti-copper agent and 0.1-2 parts of antioxidant.

2. The polypropylene-based semiconductive shielding material according to claim 1, characterized in that: The polar monomer includes at least one of maleic anhydride and styrene.

3. The polypropylene-based semiconductive shielding material according to claim 1, characterized in that: The polar monomer grafted elastomer is at least one of styrene grafted polyolefin elastomer, maleic anhydride grafted polyolefin elastomer, styrene grafted styrene-butadiene-styrene block copolymer, and maleic anhydride grafted styrene-butadiene-styrene block copolymer.

4. The polypropylene-based semiconductive shielding material according to claim 1, characterized in that: The grafting rate of the polar monomer in the polar monomer grafted elastomer is 10% to 15%.

5. The polypropylene-based semiconductive shielding material according to claim 1, characterized in that: The polar monomer grafted polypropylene is at least one of styrene grafted polypropylene and maleic anhydride grafted polypropylene.

6. The polypropylene-based semiconductive shielding material according to claim 1, characterized in that: The grafting rate of the polar monomer in the polar monomer grafted polypropylene is 2% to 5%.

7. The polypropylene-based semiconductive shielding material according to claim 1, characterized in that: The polar monomer grafted elastomer is composed of styrene grafted styrene-butadiene-styrene block copolymer and maleic anhydride grafted styrene-butadiene-styrene block copolymer in a weight ratio of (2-3):

1.

8. The polypropylene-based semiconductive shielding material according to claim 1, characterized in that: The polar monomer grafted polypropylene is composed of styrene grafted polypropylene and maleic anhydride grafted polypropylene in a weight ratio of 1:(1-2).

9. The polypropylene-based semiconductive shielding material according to claim 1, characterized in that: The polypropylene-based semiconductive shielding material also includes 0 to 16 parts of a radiation protection agent; and / or the melting point of the polypropylene does not exceed 130°C, and the melt index does not exceed 4g / 10min; and / or the iodine absorption value of the conductive carbon black is ≥160g / kg, and the oil absorption value is ≥130mL / 100g; and / or the initiator includes at least one of dilauroyl peroxide, dicyclohexyl peroxydicarbonate, isopropylbenzene hydroperoxide and diisopropylbenzene peroxide; and / or the anti-copper agent includes at least one of bis(3,5-di-tert-butyl-4-hydroxy-phenylpropionyl)hydrazine and 2,2-oxalamido-bis[ethyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)]propionate; and / or the antioxidant includes at least one of a hindered phenol antioxidant and a phosphite antioxidant; and / or the lubricant includes at least one of polypropylene wax, polyethylene wax and microcrystalline wax.

10. A method for preparing the polypropylene-based semiconductive shielding material according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: 90wt% to 95wt% of polypropylene, a polar monomer grafted elastomer, a polar monomer grafted polypropylene and an initiator are melt-mixed at high temperature, conductive carbon black is added, melt-mixed at high temperature, and then the remaining polypropylene, an antioxidant, an anti-copper agent and a lubricant are added, melt-mixed at high temperature is continued, and extrusion granulation is performed to obtain the polypropylene-based semi-conductive shielding material.

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