Polypropylene-based semiconductive shielding material, preparation method thereof and cable

Abstract

The invention relates to the technical field of electric power engineering materials, in particular to a polypropylene-based semiconductive shielding material, a preparation method thereof and a cable. The polypropylene-based semiconductive shielding material provided by the invention is prepared from the following components in parts by weight: 34 to 63 parts of polypropylene resin, 7 to 28 parts of ethylene-propylene copolymer elastomer and 20 to 30 parts of conductive carbon black, wherein the crystallinity of the polypropylene resin is 30%-35%, and the melting point of the polypropylene resin is 155-160 DEG C; the mass percent of vinyl in the ethylene-propylene copolymer elastomer is 14%-18%; the carbon black oil absorption value of the conductive carbon black is 145 mL / 100 g to 150 mL / 100 g. In the polypropylene-based semi-conductive shielding material provided by the invention, the polypropylene resin and the ethylene-propylene copolymer elastomer have excellent compatibility, so that the use of the elastomer can be effectively reduced, and the polypropylene-based semi-conductive shielding material has the advantages of relatively low cost and excellent mechanical strength and electrical performance.

Description

Technical Field

[0001] The present application relates to the technical field of electric power engineering materials, and in particular to a polypropylene-based semi-conductive shielding material and a preparation method and a cable thereof. Background Art

[0002] High-voltage cable transmission has the characteristics of long distance, large capacity and low loss. It is the core electrical equipment for urban power transmission, cross-river and offshore power transmission. Among them, the semi-conductive shielding layer is an important component of the high-voltage cable. It has the function of eliminating the defects between the metal conductor and the insulation layer and uniform interface electric field distribution. Its existence plays an important role in ensuring the long-term operation, safety and stability of the cable.

[0003] At present, cross-linked polyethylene (XLPE) is usually used as the base resin in the semi-conductive shielding layer. It has excellent electrical insulation and high temperature resistance. However, XLPE has the disadvantages of high production equipment cost, easy mixing of impurities during the manufacturing process and difficulty in recycling. Therefore, finding or developing substitutes to make up for these shortcomings is one of the important directions of current research and development. Polypropylene resin (PP) is an environmentally friendly material, but its high hardness and brittleness also limit its application. At present, the hardness of polypropylene is usually reduced by adding a certain proportion of low modulus elastomer. However, the addition of a large amount of elastomer also has the disadvantages of a surge in costs; and the uneven distribution of conductive carbon black in the semi-conductive shielding material affects the mechanical strength of the shielding material. Summary of the invention

[0004] Based on this, the present application provides a polypropylene-based semi-conductive shielding material and a preparation method and a cable. In the polypropylene-based semi-conductive shielding material provided in the present application, the polypropylene resin and the ethylene-propylene copolymer elastomer have excellent compatibility, which can effectively reduce the use of the elastomer, making it have the advantages of low cost, excellent mechanical strength and electrical performance.

[0005] In a first aspect of the present application, a polypropylene-based semiconductive shielding material is provided. The raw materials for preparing the polypropylene-based semiconductive shielding material include the following components in parts by weight: 34 to 63 parts of polypropylene resin, 7 to 28 parts of ethylene-propylene copolymer elastomer, and 20 to 30 parts of conductive carbon black;

[0006] The crystallinity of the polypropylene resin is 30% to 35%, and the melting point of the polypropylene resin is 155° C. to 160° C. The mass percentage of vinyl in the ethylene-propylene copolymer elastomer is 14% to 18%;

[0007] The conductive carbon black has an oil absorption value of 145 mL / 100 g to 150 mL / 100 g.

[0008] In one embodiment, the polypropylene resin includes a polypropylene matrix and a rubber phase.

[0009] In one embodiment, the polypropylene resin has one or more of the following characteristics:

[0010] (1) In the polypropylene resin, the mass percentage of the rubber phase is 18% to 22%;

[0011] (2) In the polypropylene resin, the rubber phase is ethylene-propylene rubber;

[0012] (3) In the polypropylene resin, the phase size of the rubber phase is 0.5 μm to 1.5 μm.

[0013] In one embodiment, the ethylene-propylene copolymer elastomer has one or more of the following characteristics:

[0014] (1) The melt index of the ethylene-propylene copolymer elastomer at 230°C × 2.16kg load is 1g / 10min~1.2g / 10min;

[0015] (2) The crystallinity of the ethylene-propylene copolymer elastomer is 5% to 15%.

[0016] In one of the embodiments, the raw materials for preparing the polypropylene-based semi-conductive shielding material further include functional additives, and the functional additives include one or more of antioxidants, lubricants and dispersants.

[0017] In one embodiment, the raw materials for preparing the polypropylene-based semi-conductive shielding material include the following components, measured in parts by weight: 34 to 63 parts of polypropylene resin, 7 to 28 parts of ethylene-propylene copolymer elastomer, 20 to 30 parts of conductive carbon black, 0.5 to 1 part of antioxidant, 1 to 2 parts of lubricant, and 2 to 4 parts of dispersant.

[0018] In one embodiment, the polypropylene-based semiconductive shielding material has one or more of the following characteristics:

[0019] (1) The antioxidant includes one or more of hindered phenol antioxidants, phosphite antioxidants and thiophenol antioxidants;

[0020] (2) The lubricating oil includes one or more of zinc stearate and pentaerythritol;

[0021] (3) The dispersant includes one or more of oleic acid amide and ethylene bisstearamide.

[0022] In a second aspect of the present application, there is provided a method for preparing the polypropylene-based semiconductive shielding material according to any one of the embodiments of the first aspect of the present application, comprising the following steps:

[0023] The raw materials are selected according to weight proportions, and melt-blended to prepare the polypropylene-based semi-conductive shielding material.

[0024] In one embodiment, the melt blending method includes one or more of mixing and extrusion; and / or,

[0025] The temperature of the melt blending is 180°C to 220°C.

[0026] A third aspect of the present application provides a cable, comprising the polypropylene-based semi-conductive shielding material described in any one of the embodiments of the first aspect of the present application.

[0027] This application has the following beneficial effects:

[0028] The polypropylene-based semi-conductive shielding material provided in the present application is prepared by selecting a polypropylene resin with a specific crystallinity and a specific melting point. At this time, the crystalline region in the polypropylene resin can give the polypropylene resin appropriate mechanical strength and can effectively resist the movement of molecular chains at high temperatures to ensure the heat resistance of the polypropylene-based semi-conductive shielding material; at the same time, the non-crystalline region can give the polypropylene resin appropriate toughness.

[0029] Ethylene-propylene copolymer elastomer with a specific vinyl content can ensure sufficient elasticity, ensure its overall heat resistance, and improve the impact resistance of polypropylene resin. The above-mentioned polypropylene resin and ethylene-propylene copolymer elastomer have good compatibility, which can effectively reduce the phase interface between the components, which is conducive to reducing the addition amount of ethylene-propylene copolymer elastomer and making the conductive carbon black evenly dispersed. Furthermore, the conductive carbon black with a carbon black oil absorption value of 145 mL / 100g~150 mL / 100g has a moderate degree of structure and can form an effective conductive network. In summary, the present application can obtain a polypropylene-based semi-conductive shielding material with excellent mechanical properties, electrical properties and heat resistance by selecting specific polypropylene resins, ethylene-propylene copolymer elastomers and conductive carbon black, and by reasonably matching the weight proportions of each component. DETAILED DESCRIPTION

[0030] The following is a further complete and clear description of the polypropylene-based semiconductive shielding material and its preparation method and cable of the present application in conjunction with specific embodiments. The present application can be implemented 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 understanding of the disclosure of the present application more thorough and comprehensive.

[0031] In traditional semi-conductive shielding materials based on polypropylene resin, due to the properties of polypropylene resin, it is often necessary to add more elastomers, which not only increases production costs, but also reduces the heat resistance of the insulating material due to the poor heat resistance of the elastomer.

[0032] Based on this, the first aspect of the present application provides a polypropylene-based semi-conductive shielding material, wherein the raw materials for preparing the polypropylene-based semi-conductive shielding material include the following components in parts by weight: 34 to 63 parts of polypropylene resin, 7 to 28 parts of ethylene-propylene copolymer elastomer, and 20 to 30 parts of conductive carbon black;

[0033] The crystallinity of the polypropylene resin is 30% to 35%, and the melting point of the polypropylene resin is 155° C. to 160° C. The mass percentage of vinyl in the ethylene-propylene copolymer elastomer is 14% to 18%;

[0034] The conductive carbon black has an oil absorption value of 145 mL / 100 g to 150 mL / 100 g.

[0035] It is understandable that in the present application, the weight parts of polypropylene resin can be selected from any value between 34 parts ~ 63 parts. Specifically, the weight parts of polypropylene resin include but are not limited to 34 parts, 35 parts, 36 parts, 37 parts, 38 parts, 39 parts, 40 parts, 41 parts, 42 parts, 43 parts, 45 parts, 48 ​​parts, 50 parts, 53 parts, 55 parts, 56 parts, 57 parts, 58 parts, 60 parts, 62 parts or 63 parts. The weight parts of ethylene-propylene copolymer elastomer can be selected from any value between 7 parts ~ 28 parts. Specifically, the weight parts of ethylene-propylene copolymer elastomer include but are not limited to 7 parts, 8 parts, 9 parts, 12 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 20 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts or 28 parts. Specifically, the weight percentage of the conductive carbon black includes, but is not limited to, 20 parts, 22 parts, 25 parts, 28 parts, 29 parts or 30 parts.

[0036] The crystallinity of the polypropylene resin can be selected from any value between 30% and 35%. Specifically, the crystallinity of the polypropylene resin includes but is not limited to 30.5%, 31%, 31.5%, 32%, 32.5%, 33%, 33.2%, 33.3%, 33.4%, 33.5%, 33.6%, 33.8%, 34%, 34.3%, 34.6%, 34.8%, 34.9% or 35%. The melting point of the polypropylene resin can be selected from any value between 155°C and 160°C. Specifically, the melting point of the polypropylene resin includes but is not limited to 155°C, 156°C, 157°C, 158°C, 159°C or 160°C. The mass percentage of vinyl in the ethylene-propylene copolymer elastomer can be selected from any value between 14% and 18%. Specifically, the mass percentage of vinyl group in the ethylene-propylene copolymer elastomer includes but is not limited to 14%, 14.5%, 14.8%, 15%, 15.2%, 15.5%, 15.8%, 16%, 16.5%, 16.8%, 17%, 17.5%, 17.8% or 18%.

[0037] The carbon black oil absorption value of the conductive carbon black can be selected from any value between 145 mL / 100g and 150 mL / 100g. Specifically, the carbon black oil absorption value of the conductive carbon black includes but is not limited to 145 mL / 100g, 146 mL / 100g, 147 mL / 100g, 148 mL / 100g, 149 mL / 100g or 150 mL / 100g.

[0038] The polypropylene-based semi-conductive shielding material provided in the present application is prepared by selecting a polypropylene resin with a specific crystallinity and a specific melting point. At this time, the crystalline region in the polypropylene resin can give the polypropylene resin appropriate mechanical strength and can effectively resist the movement of molecular chains at high temperatures to ensure the heat resistance of the polypropylene-based semi-conductive shielding material; at the same time, the non-crystalline region can give the polypropylene resin appropriate toughness.

[0039] Ethylene-propylene copolymer elastomer with a specific vinyl content can ensure sufficient elasticity, ensure its overall heat resistance, and improve the impact resistance of polypropylene resin. The above-mentioned polypropylene resin and ethylene-propylene copolymer elastomer have good compatibility, which can effectively reduce the phase interface between the components, which is conducive to reducing the addition amount of ethylene-propylene copolymer elastomer and making the conductive carbon black evenly dispersed. Furthermore, the conductive carbon black with a carbon black oil absorption value of 145 mL / 100g~150 mL / 100g has a moderate degree of structure and can form an effective conductive network. In summary, the present application can obtain a polypropylene-based semi-conductive shielding material with excellent mechanical properties, electrical properties and heat resistance by selecting specific polypropylene resins, ethylene-propylene copolymer elastomers and conductive carbon black, and by reasonably matching the weight proportions of each component.

[0040] In one example, the polypropylene resin includes a polypropylene matrix and a rubber phase.

[0041] Defining the mass percentage of the rubber phase in the polypropylene resin plays an important role in ensuring the crystallinity and melting point of the polypropylene resin. At the same time, the rubber phase can also absorb and disperse stress, reduce stress concentration, and improve the brittleness of the polypropylene matrix. In one example, in the polypropylene resin, the mass percentage of the rubber phase is 18% to 22%. It can be understood that in the polypropylene resin, the mass percentage of the rubber phase can be selected from any value between 18% and 22%. Specifically, in the polypropylene resin, the mass percentage of the rubber phase includes but is not limited to 18%, 19%, 20%, 21% or 22%.

[0042] In one example, in the polypropylene resin, the rubber phase is ethylene-propylene rubber.

[0043] In order to make the rubber phase in the polypropylene resin evenly dispersed, the effective toughening of the polypropylene resin is achieved. In one example, in the polypropylene resin, the phase size of the rubber phase is 0.5μm~1.5μm. Specifically, the phase size of the rubber phase in the polypropylene resin includes but is not limited to 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1.0μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm or 1.5μm.

[0044] In one example, the melt index of the ethylene-propylene copolymer elastomer at 230°C×2.16kg load is 1g / 10min~1.2g / 10min. Specifically, the melt index of the ethylene-propylene copolymer elastomer includes but is not limited to 1g / 10min, 1.05g / 10min, 1.08g / 10min, 1.1g / 10min, 1.12g / 10min, 1.15g / 10min, 1.18g / 10min or 1.2g / 10min.

[0045] In one example, the crystallinity of the ethylene-propylene copolymer elastomer is 5% to 15%. Specifically, the crystallinity of the ethylene-propylene copolymer elastomer includes but is not limited to 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15%. The crystallinity of the ethylene-propylene copolymer elastomer is limited to 5% to 15%, and the amorphous region existing therein can interpenetrate and entangle with the amorphous region of the polypropylene resin, thereby achieving a tighter interface bonding and enhancing the compatibility between the polypropylene resin and the ethylene-propylene copolymer elastomer.

[0046] In one example, the raw materials for preparing the polypropylene-based semi-conductive shielding material further include functional additives, and the functional additives include one or more of antioxidants, lubricants and dispersants.

[0047] In one example, the raw materials for preparing the polypropylene-based semi-conductive shielding material include the following components, measured in parts by weight: 34 to 63 parts of polypropylene resin, 7 to 28 parts of ethylene-propylene copolymer elastomer, 20 to 30 parts of conductive carbon black, 0.5 to 1 part of antioxidant, 1 to 2 parts of lubricant, and 2 to 4 parts of dispersant.

[0048] It is understandable that the weight portion of the antioxidant can be selected from any value between 0.5 and 1. Specifically, the weight portion of the antioxidant includes but is not limited to 0.5, 0.6, 0.7, 0.8, 0.9 or 1. The weight portion of the lubricant includes but is not limited to 1, 1.1, 1.2, 1.3, 1.5, 1.6, 1.8, 1.9 or 2. The weight portion of the dispersant includes but is not limited to 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.5, 3.8 or 4.

[0049] Antioxidants can effectively capture free radicals, inhibit or delay the degradation of materials caused by oxidation during processing and use, and extend the service life of semi-conductive shielding materials. In one example, the antioxidant includes one or more of hindered phenol antioxidants, phosphite antioxidants and thiophenol antioxidants. It is understandable that the present application does not limit the specific types of hindered phenol antioxidants, phosphite antioxidants and thiophenol antioxidants. For example, hindered phenol antioxidants can be exemplified as antioxidant 1010. Phosphite antioxidants can be exemplified as antioxidant 168. Thiophenol antioxidants can be exemplified as antioxidant 300.

[0050] The lubricating oil can reduce the friction coefficient of the semi-conductive shielding material during the preparation process, reduce the heat and wear generated during the processing, and the adhesion of the material on the inner wall of the processing equipment, and ensure the surface finish of the semi-conductive shielding material. In one example, the lubricating oil includes one or more of zinc stearate and pentaerythritol.

[0051] In order to further increase the dispersibility of each component in the semi-conductive shielding material, avoid component agglomeration, and ensure the continuity of the conductive network, in one example, the dispersant includes one or more of oleic acid amide and ethylene bisstearamide.

[0052] In a second aspect of the present application, there is provided a method for preparing a polypropylene-based semiconductive shielding material as described in any example of the first aspect of the present application, comprising the following steps:

[0053] The raw materials are selected according to weight proportions, and melt-blended to prepare the polypropylene-based semi-conductive shielding material.

[0054] In one example, the melt blending method includes one or more of internal mixing and extrusion. It can be understood that internal mixing can make the raw materials mixed more uniformly; after extrusion, the polypropylene-based semi-conductive shielding material prepared at this time is a granular material.

[0055] In one example, the temperature of the melt blending is 180° C. to 220° C. Specifically, the temperature of the melt blending includes but is not limited to 180° C., 185° C., 190° C., 195° C., 200° C., 205° C., 210° C., 215° C. or 220° C.

[0056] In one example, the melt blending time is 5 min to 10 min.

[0057] In one example, the speed of the melt blending is 80 r / min to 150 r / min. Specifically, the speed of the melt blending includes but is not limited to 80 r / min, 85 r / min, 90 r / min, 95 r / min, 100 r / min, 105 r / min, 110 r / min, 115 r / min, 120 r / min, 130 r / min, 140 r / min, 145 r / min or 150 r / min.

[0058] In one specific example, the method for preparing the polypropylene-based semi-conductive shielding material includes the following steps: selecting the preparation raw materials according to weight proportions, and preparing the polypropylene-based semi-conductive shielding material after melt blending.

[0059] In one example, the method for preparing the polypropylene-based semi-conductive shielding material further includes the step of hot pressing the polypropylene-based semi-conductive shielding material, as follows:

[0060] The polypropylene-based semiconductive shielding material is hot-pressed at 170° C. to 190° C. and cooled.

[0061] Specifically, the equipment for hot pressing can be selected from a flat vulcanizer. The temperature of hot pressing includes but is not limited to 170° C., 172° C., 173° C., 175° C., 178° C., 180° C., 185° C., 188° C. or 190° C. The polypropylene-based semi-conductive shielding material is hot-pressed to obtain a high-precision molded product.

[0062] In one specific example, the step of hot pressing the polypropylene-based semi-conductive shielding material specifically includes:

[0063] The semi-conductive shielding material is placed in a flat plate vulcanizer, the pressing plate temperature is set to 170° C. to 190° C., hot-pressed for 10 min to 20 min, and then cooled.

[0064] A third aspect of the present application provides a cable, comprising the polypropylene-based semi-conductive shielding material described in any example of the first aspect of the present application.

[0065] The following further specific examples are provided to explain the present application in detail. It should also be understood that the following examples are only used to further explain the present application and cannot be understood as limiting the scope of protection of the present application. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present application belong to the scope of protection of the present application. The specific process parameters of the following embodiments are also only examples within a suitable range, that is, those skilled in the art can make a selection within a suitable range through the description herein, and are not necessarily limited to the specific values ​​of the embodiments below.

[0066] Example 1

[0067] 63 parts of polypropylene resin, 7 parts of ethylene-propylene copolymer elastomer and 30 parts of conductive carbon black were weighed as preparation raw materials; wherein, the polypropylene resin has a crystallinity of 33.4% and a melting point of 156°C, the polypropylene resin includes 20% by mass of ethylene-propylene rubber, and the average phase size of the ethylene-propylene rubber is 1.3 μm.

[0068] The melt index of the ethylene-propylene copolymer elastomer at 230° C.×2.16 kg load is 1.1 g / 10 min, the mass percentage of vinyl in the ethylene-propylene copolymer elastomer is 15%, and the crystallinity is 9%.

[0069] The carbon black oil absorption value of the conductive carbon black is 148 mL / 100 g.

[0070] Polypropylene resin, ethylene-propylene copolymer elastomer and conductive carbon black are placed in an internal mixer for melt blending to obtain a polypropylene-based semi-conductive shielding material. The melt blending process is: temperature 180° C., time 10 minutes, and rotation speed 80 r / min.

[0071] Example 2

[0072] 54 parts of polypropylene resin, 16 parts of ethylene-propylene copolymer elastomer and 30 parts of conductive carbon black were weighed as preparation raw materials; wherein, the polypropylene resin had a crystallinity of 33.4% and a melting point of 156°C, the polypropylene resin included 20% by mass of ethylene-propylene rubber, and the average phase size of the ethylene-propylene rubber was 1.3 μm.

[0073] The melt index of the ethylene-propylene copolymer elastomer at 230° C.×2.16 kg load is 1.1 g / 10 min, the mass percentage of vinyl in the ethylene-propylene copolymer elastomer is 15%, and the crystallinity is 9%.

[0074] The carbon black oil absorption value of the conductive carbon black is 148 mL / 100 g.

[0075] Polypropylene resin, ethylene-propylene copolymer elastomer and conductive carbon black are placed in an internal mixer for melt blending to obtain a polypropylene-based semi-conductive shielding material. The melt blending process is: temperature 180° C., time 10 minutes, and rotation speed 80 r / min.

[0076] Example 3

[0077] 46 parts of polypropylene resin, 24 parts of ethylene-propylene copolymer elastomer and 30 parts of conductive carbon black were weighed as preparation raw materials; wherein, the polypropylene resin had a crystallinity of 33.4% and a melting point of 156°C, the polypropylene resin included ethylene-propylene rubber accounting for 20% by mass, and the average phase size of the ethylene-propylene rubber was 1.3 μm.

[0078] The melt index of the ethylene-propylene copolymer elastomer at 230° C.×2.16 kg load is 1.1 g / 10 min, the mass percentage of vinyl in the ethylene-propylene copolymer elastomer is 15%, and the crystallinity is 9%.

[0079] The carbon black oil absorption value of the conductive carbon black is 148 mL / 100 g.

[0080] Polypropylene resin, ethylene-propylene copolymer elastomer and conductive carbon black are placed in an internal mixer for melt blending to obtain a polypropylene-based semi-conductive shielding material. The melt blending process is: temperature 180° C., time 10 minutes, and rotation speed 80 r / min.

[0081] Example 4

[0082] 42 parts of polypropylene resin, 28 parts of ethylene-propylene copolymer elastomer and 30 parts of conductive carbon black were weighed as preparation raw materials; wherein, the polypropylene resin had a crystallinity of 33.4% and a melting point of 156°C, the polypropylene resin included 20% by mass of ethylene-propylene rubber, and the average phase size of the ethylene-propylene rubber was 1.3 μm.

[0083] The melt index of the ethylene-propylene copolymer elastomer at 230° C.×2.16 kg load is 1.1 g / 10 min, the mass percentage of vinyl in the ethylene-propylene copolymer elastomer is 15%, and the crystallinity is 9%.

[0084] The carbon black oil absorption value of the conductive carbon black is 148 mL / 100 g.

[0085] Polypropylene resin, ethylene-propylene copolymer elastomer and conductive carbon black are placed in an internal mixer for melt blending to obtain a polypropylene-based semi-conductive shielding material. The melt blending process is: temperature 180° C., time 10 minutes, and rotation speed 80 r / min.

[0086] Example 5

[0087] 46 parts of polypropylene resin, 24 parts of ethylene-propylene copolymer elastomer and 30 parts of conductive carbon black were weighed as preparation raw materials; wherein, the polypropylene resin has a crystallinity of 30% and a melting point of 155°C, the polypropylene resin includes 22% by mass of ethylene-propylene rubber, and the average phase size of the ethylene-propylene rubber is 1.3 μm.

[0088] The melt index of the ethylene-propylene copolymer elastomer at 230° C.×2.16 kg load is 1.2 g / 10 min, the mass percentage of vinyl in the ethylene-propylene copolymer elastomer is 14%, and the crystallinity is 5%.

[0089] The carbon black oil absorption value of the conductive carbon black is 145 mL / 100 g.

[0090] Polypropylene resin, ethylene-propylene copolymer elastomer and conductive carbon black are placed in an internal mixer for melt blending to obtain a polypropylene-based semi-conductive shielding material. The melt blending process is: temperature 180° C., time 10 minutes, and rotation speed 80 r / min.

[0091] Example 6

[0092] 46 parts of polypropylene resin, 24 parts of ethylene-propylene copolymer elastomer and 30 parts of conductive carbon black were weighed as preparation raw materials; wherein, the polypropylene resin had a crystallinity of 35% and a melting point of 160°C, the polypropylene resin included 18% by mass of ethylene-propylene rubber, and the average phase size of the ethylene-propylene rubber was 1.3 μm.

[0093] The melt index of the ethylene-propylene copolymer elastomer at 230° C.×2.16 kg load is 1 g / 10 min, the mass percentage of vinyl in the ethylene-propylene copolymer elastomer is 18%, and the crystallinity is 5%.

[0094] The carbon black oil absorption value of conductive carbon black is 150 mL / 100g.

[0095] Polypropylene resin, ethylene-propylene copolymer elastomer and conductive carbon black are placed in an internal mixer for melt blending to obtain a polypropylene-based semi-conductive shielding material. The melt blending process is: temperature 180° C., time 10 minutes, and rotation speed 80 r / min.

[0096] Comparative Example 1

[0097] 70 parts of polypropylene resin and 30 parts of conductive carbon black were weighed as raw materials for preparation; wherein, the polypropylene resin had a crystallinity of 33.4% and a melting point of 156°C, the polypropylene resin included ethylene-propylene rubber accounting for 20% by mass, and the average phase size of the ethylene-propylene rubber was 1.3 μm.

[0098] The carbon black oil absorption value of the conductive carbon black is 148 mL / 100 g.

[0099] The polypropylene resin and the conductive carbon black are placed in an internal mixer for melt blending to obtain a polypropylene-based semi-conductive shielding material. The melt blending process is as follows: temperature 180° C., time 10 minutes, and rotation speed 80 r / min.

[0100] Comparative Example 2

[0101] 46 parts of polypropylene resin, 24 parts of ethylene-octene copolymer elastomer and 30 parts of conductive carbon black were weighed as preparation raw materials; wherein, the polypropylene resin had a crystallinity of 33.4% and a melting point of 156°C, the polypropylene resin included 20% by mass of ethylene-propylene rubber, and the average phase size of the ethylene-propylene rubber was 1.3 μm.

[0102] The melt index of the ethylene-octene copolymer elastomer at 230° C.×2.16 kg load is 2.5 g / 10 min, the mass percentage of octenyl in the ethylene-propylene copolymer elastomer is 38%, and the crystallinity is 6%.

[0103] The carbon black oil absorption value of the conductive carbon black is 148 mL / 100 g.

[0104] Polypropylene resin, ethylene-octene copolymer elastomer and conductive carbon black are placed in an internal mixer for melt blending to obtain a polypropylene-based semi-conductive shielding material. The melt blending process is: temperature 180° C., time 10 minutes, and rotation speed 80 r / min.

[0105] Comparative Example 3

[0106] 46 parts of polypropylene resin, 24 parts of ethylene-propylene-diene terpolymer elastomer and 30 parts of conductive carbon black were weighed as preparation raw materials; wherein the polypropylene resin had a crystallinity of 33.4% and a melting point of 156°C, the polypropylene resin included 20% by mass of ethylene-propylene rubber, and the average phase size of the ethylene-propylene rubber was 1.3 μm.

[0107] The melt index of the ethylene-propylene-diene terpolymer elastomer at 230° C.×2.16 kg load is 7.3 g / 10 min, the mass percentage of vinyl in the ethylene-propylene copolymer elastomer is 56%, and the crystallinity is 2%.

[0108] The carbon black oil absorption value of the conductive carbon black is 148 mL / 100 g.

[0109] Polypropylene resin, ethylene-propylene copolymer elastomer and conductive carbon black are placed in an internal mixer for melt blending to obtain a polypropylene-based semi-conductive shielding material. The melt blending process is: temperature 180° C., time 10 minutes, and rotation speed 80 r / min.

[0110] Comparative Example 4

[0111] 46 parts of polypropylene resin, 24 parts of styrene-ethylene-butylene-styrene block copolymer and 30 parts of conductive carbon black were weighed as preparation raw materials; wherein the polypropylene resin had a crystallinity of 33.4% and a melting point of 156°C, the polypropylene resin included 20% by mass of ethylene-propylene rubber, and the average phase size of the ethylene-propylene rubber was 1.3 μm.

[0112] The melt index of the styrene-ethylene-butylene-styrene block copolymer at 230° C.×2.16 kg load is 11 g / 10 min. The mass percentage of vinyl in the styrene-ethylene-butylene-styrene block copolymer is 35%, and the crystallinity is 20%.

[0113] The carbon black oil absorption value of the conductive carbon black is 148 mL / 100 g.

[0114] Polypropylene resin, styrene-ethylene-butylene-styrene block copolymer and conductive carbon black are placed in an internal mixer for melt blending to obtain a polypropylene-based semi-conductive shielding material. The melt blending process is: temperature 180° C., time 10 minutes, and rotation speed 80 r / min.

[0115] The weight percentages of the raw materials and the properties of the raw materials in the examples and comparative examples are shown in Tables 1 and 2 below.

[0116] Table 1

[0117]

[0118] Table 2

[0119]

[0120] The polypropylene-based insulating materials prepared in the examples and comparative examples were tested for tensile strength, elongation at break, volume resistivity at 23°C, and volume resistivity at 90°C. The corresponding test standards are as follows:

[0121] (1) Tensile strength: tested based on GB / T1040.2;

[0122] (2) Elongation at break: tested based on GB / T1040.2;

[0123] (3) Volume resistivity at 23°C: tested based on GB / T3048.3;

[0124] (4) Volume resistivity at 90°C, tested based on GB / T3048.3; the corresponding test results are shown in Table 3.

[0125] Table 3

[0126]

[0127] As can be seen from Table 1 to Table 3, in Comparative Example 1 and Example 1 to Example 4, the weight percentage of the conductive carbon black is the same, but the percentage of the added ethylene-propylene copolymer elastomer gradually increases, and the performance of the semi-conductive shielding material changes significantly. The main reason for the change in the performance of the semi-conductive shielding material in Comparative Example 1 and Example 1 to Example 4 is that the addition of the ethylene-propylene copolymer elastomer reduces the glass transition temperature (Tg) of the semi-conductive shielding material and improves the mobility of the polymer chain, thereby making the material more easily deformed when subjected to external force, increasing its flexibility and increasing its elongation at break.

[0128] In Example 3 and Comparative Examples 2 to 4, the polypropylene resin and the conductive carbon black are the same, but the added elastomers are different. It can be found from Example 3 and Comparative Examples 2 to 4 that the mechanical properties of the semi-conductive shielding material are significantly improved by adding ethylene-propylene copolymer elastomers with a vinyl mass percentage of 14% to 18% compared with other elastomers of the same amount. The main reason for this phenomenon is that the ethylene-propylene copolymer elastomer with specific properties defined in this application can effectively improve its compatibility with polypropylene resin and conductive carbon black to form a good microphase structure; this enables the elastomer and polypropylene to effectively transfer loads under the action of external forces, thereby improving the overall load-bearing capacity and elongation at break of the semi-conductive shielding material; in addition, the uniformity of the distribution of conductive carbon black also makes the semi-conductive shielding material have better electrical properties.

[0129] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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.

[0130] The above-described embodiments only express several implementation methods of the present application, which is convenient for understanding the technical solution of the present application in detail, but it 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 modifications and improvements can be made, which all belong to 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-based semiconductive shielding material, characterized in that: The raw materials for preparing the polypropylene-based semi-conductive shielding material include the following components in parts by weight: 34 to 63 parts of polypropylene resin, 7 to 28 parts of ethylene-propylene copolymer elastomer, and 20 to 30 parts of conductive carbon black; The crystallinity of the polypropylene resin is 30% to 35%, and the melting point of the polypropylene resin is 155° C. to 160° C. The mass percentage of vinyl in the ethylene-propylene copolymer elastomer is 14% to 18%; The conductive carbon black has an oil absorption value of 145 mL / 100 g to 150 mL / 100 g.

2. The polypropylene-based semiconductive shielding material according to claim 1, characterized in that: The polypropylene resin comprises a polypropylene matrix and a rubber phase.

3. The polypropylene-based semiconductive shielding material according to claim 2, characterized in that: The polypropylene resin has one or more of the following characteristics: (1) In the polypropylene resin, the mass percentage of the rubber phase is 18% to 22%; (2) In the polypropylene resin, the rubber phase is ethylene-propylene rubber; (3) In the polypropylene resin, the phase size of the rubber phase is 0.5 μm to 1.5 μm.

4. The polypropylene-based semiconductive shielding material according to claim 1, characterized in that: The ethylene-propylene copolymer elastomer has one or more of the following characteristics: (1) The melt index of the ethylene-propylene copolymer elastomer at 230°C × 2.16kg load is 1g / 10min~1.2g / 10min; (2) The crystallinity of the ethylene-propylene copolymer elastomer is 5% to 15%.

5. The polypropylene-based semiconductive shielding material according to any one of claims 1 to 4, characterized in that: The raw materials for preparing the polypropylene-based semi-conductive shielding material also include functional additives, and the functional additives include one or more of antioxidants, lubricants and dispersants.

6. The polypropylene-based semiconductive shielding material according to claim 5, characterized in that: The raw materials for preparing the polypropylene-based semi-conductive shielding material include the following components in parts by weight: 34 to 63 parts of polypropylene resin, 7 to 28 parts of ethylene-propylene copolymer elastomer, 20 to 30 parts of conductive carbon black, 0.5 to 1 part of antioxidant, 1 to 2 parts of lubricant, and 2 to 4 parts of dispersant.

7. The polypropylene-based semiconductive shielding material according to claim 6, characterized in that: The polypropylene-based semiconductive shielding material has one or more of the following characteristics: (1) The antioxidant includes one or more of hindered phenol antioxidants, phosphite antioxidants and thiophenol antioxidants; (2) The lubricating oil includes one or more of zinc stearate and pentaerythritol; (3) The dispersant includes one or more of oleic acid amide and ethylene bisstearamide.

8. A method for preparing the polypropylene-based semiconductive shielding material according to any one of claims 1 to 7, characterized in that: The following steps are involved: The raw materials are selected according to weight proportions, and melt-blended to prepare the polypropylene-based semi-conductive shielding material.

9. The method for preparing the polypropylene-based semiconductive shielding material according to claim 8, characterized in that: The melt blending method includes one or more of banburying and extrusion; and / or, The temperature of the melt blending is 180°C to 220°C.

10. A cable, characterized in that: The invention comprises the polypropylene-based semiconductive shielding material as described in any one of claims 1 to 7.

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