Thermoplastic polyvinyl semiconductive shielding material and preparation method thereof

Abstract

The invention discloses a thermoplastic polyvinyl semiconductive shielding material and a preparation method thereof, and relates to the technical field of composite materials. The thermoplastic polyvinyl semiconductive shielding material comprises the following components in parts by weight: 65-74 parts of polyethylene resin; 20 to 30 parts of conductive carbon black; 2-6 parts of an auxiliary agent; the melt index of the polyethylene resin under the condition of 190 DEG C / 2.16 kg is 0.15-0.25 g / 10 min, and the polyethylene is linear low-density polyethylene. According to the semi-conductive shielding material and the preparation method thereof, polyethylene with set density and melt index is selected as matrix resin and conductive carbon black with set parts, and the semi-conductive shielding material prepared by the preparation method disclosed by the invention is adopted, so that the conductive carbon black in the shielding material is dispersed more uniformly, and the material has excellent electrical characteristics and good mechanical properties.

Description

Technical Field

[0001] The invention relates to the technical field of composite materials, and in particular to a thermoplastic polyethylene-based semi-conductive shielding material and a preparation method thereof. Background Art

[0002] Cross-linked polyethylene (XLPE) forms a spatial network structure through cross-linking reaction, which further improves its physical and chemical properties, making XLPE have excellent electrical insulation, mechanical and heat resistance. At the same time, XLPE cable has a simple structure and is easy to install. These advantages make it the mainstream of current cables and widely used in urban distribution networks. However, with the introduction of the "dual carbon" strategy, green, environmental protection and low carbon have become the direction of current industrial structure adjustment. XLPE is a thermosetting material with good thermal stability and is difficult to decompose, which makes it difficult to recycle and reuse XLPE cables after retirement and abandonment. Cables that are retired and abandoned are usually landfilled and incinerated naturally, which will cause great environmental pollution and waste of resources. In addition, XLPE cables require professional equipment to control during the industrial production process, the process is complex, and cross-linking and degassing are required. Therefore, XLPE not only pollutes the environment during the production process, but also has high manufacturing costs and energy consumption. Therefore, it is necessary to find an environmentally friendly cable insulation material to replace XLPE.

[0003] Non-cross-linked insulation materials have become the current research direction of medium and high voltage cable insulation materials due to their simple processing technology, recyclability and other low-carbon and environmentally friendly advantages. For example, thermoplastic polypropylene (PP)-based and polyethylene (PE)-based materials have become the research hotspots of non-cross-linked cable insulation materials at this stage. The research of semi-conductive shielding materials used in conjunction with non-cross-linked insulation materials is equally important.

[0004] For non-cross-linked polyethylene-based cable insulation materials, non-cross-linked shielding materials need to be used from both the environmental protection and processing perspectives. Non-cross-linked shielding materials do not have a cross-linking vulcanization process during preparation, which is beneficial to energy conservation and environmental protection. At present, extruded insulated cables usually use a three-layer co-extrusion cabling process, that is, the outer shielding layer, the insulating layer and the inner shielding layer are melted and extruded at the same time. In order to ensure that the three can be in close contact, the three need to have good compatibility. Therefore, for non-cross-linked polyethylene-based insulation materials, non-cross-linked semi-conductive shielding materials need to be used as well, which helps the two to form a good interface to achieve the purpose of uniform interface electric field distribution.

[0005] At present, the research on non-cross-linked polyethylene-based insulation materials has achieved certain results, but the research on matching non-cross-linked shielding materials is still relatively scarce, which limits the application of non-cross-linked polyethylene-based insulation materials. Therefore, it is of great significance to study non-cross-linked semi-conductive shielding materials. Therefore, it is necessary to provide a thermoplastic insulation polyethylene cable material that is easy to process. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a thermoplastic polyethylene-based semi-conductive shielding material and a preparation method thereof. The thermoplastic polyethylene-based semi-conductive shielding material provided by the present invention does not require cross-linking, and the prepared shielding material has no cross-linking byproducts and can be matched with thermoplastic polyethylene insulating materials.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] In a first aspect, the present invention provides a thermoplastic polyethylene-based semiconductive shielding material, comprising the following components in parts by weight:

[0009] Polyethylene resin 65-74 parts; conductive carbon black 20-30 parts; additives 2-6 parts;

[0010] The polyethylene resin is a linear low-density polyethylene, and the polyethylene resin has a melt index of 0.15-0.25 g / 10 min at 190° C. / 2.16 kg.

[0011] The present invention selects polyethylene of a specific type and melt index as the base resin and uses a specific amount of conductive carbon black for compounding, so that the conductive carbon black in the shielding material is more evenly dispersed, which is beneficial to improving the electrical and mechanical properties of the shielding material. At the same time, the present invention, through the design of the formula system, can make the material have excellent electrical properties and good mechanical properties without cross-linking, which can simplify the production process and effectively save production costs.

[0012] Preferably, the melt index of the polyethylene resin at 190°C / 2.16kg is in the range of any one or both of 0.15g / 10min, 0.16g / 10min, 0.17g / 10min, 0.19g / 10min, 0.20g / 10min, 0.22g / 10min, 0.24g / 10min, and 0.25g / 10min.

[0013] Preferably, the DBP absorption value of the conductive carbon black is 160-180 ml / 100 g, and the ash content is less than 0.1%.

[0014] More preferably, the DBP absorption value of the conductive carbon black is in the range of any one or both of 160 ml / 100 g, 165 ml / 100 g, 170 ml / 100 g, 175 ml / 100 g, and 180 ml / 100 g.

[0015] Preferably, the thermoplastic polyethylene-based semiconductive shielding material comprises the following components in parts by weight:

[0016] 66.5-71.5 parts of polyethylene resin; 25-30 parts of conductive carbon black; 3.5 parts of additives, a total of 100 parts.

[0017] Preferably, the auxiliary agent includes 0.5-1 parts of antioxidant and 2-4 parts of dispersant.

[0018] More preferably, the auxiliary agent includes 0.5 parts of antioxidant and 3 parts of dispersant.

[0019] Preferably, the antioxidant includes at least one of antioxidant 300 , antioxidant 1010 , and antioxidant 168 .

[0020] Preferably, the dispersant includes at least one of white oil, ethylene bisstearamide and oleamide.

[0021] In a second aspect, the present invention further provides a method for preparing a thermoplastic polyethylene-based semiconductive shielding material, comprising the following steps:

[0022] The polyethylene resin, conductive carbon black and additives are mixed evenly according to a proportion, and then melt-blended and extruded in an extruder. After compression, pelletization and drying, a thermoplastic polyethylene-based semi-conductive shielding material is obtained.

[0023] Preferably, the temperature of the melt blending extrusion is 150-180° C. and the rotation speed is 40-50 r / min.

[0024] Preferably, the drying temperature is 60-80°C and the drying time is 20-24h.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] Most of the existing commercial semi-conductive shielding materials for cables are products to be cross-linked, with a melting point of about 90°C, which are suitable for the manufacturing process of cross-linked polymer insulation cables. The thermoplastic polyethylene-based semi-conductive shielding material proposed in the present invention is a non-cross-linked material with high tensile strength and elongation at break. It has better compatibility with non-cross-linked polyethylene-based insulation materials in terms of thermal properties and material interface coordination, so as to meet the unique performance standards of thermoplastic non-cross-linked polyethylene-based cables, and greatly promote the application and promotion potential of non-cross-linked polyethylene insulated cables in the field of high-voltage power cables. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a preparation flow chart of the thermoplastic polyethylene-based semi-conductive shielding material of the present invention. DETAILED DESCRIPTION

[0028] In order 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, but the protection scope and implementation methods of the present invention are not limited thereto.

[0029] Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0030] Example 1

[0031] A thermoplastic polyethylene-based semiconductive shielding material comprises the following components in parts by weight: 66.5 parts of polyethylene resin, 30 parts of conductive carbon black, and 3.5 parts of auxiliary agent, which is a total of 100 parts.

[0032] The polyethylene resin is a linear low-density polyethylene, and the melt index at 190° C. / 2.16 kg is 0.15 g / 10 min.

[0033] The DBP absorption value of the conductive carbon black is 160 ml / 100 g, and the ash content is less than 0.1%.

[0034] The auxiliary agent includes 0.5 parts of antioxidant and 3 parts of dispersant; the antioxidant is antioxidant 300; and the dispersant is ethylene bis stearamide.

[0035] This embodiment also discloses a method for preparing a thermoplastic polyethylene-based semiconductive shielding material, comprising the following steps:

[0036] S1. Take out the corresponding polyethylene resin, conductive carbon black and additives according to the ratio, and dry them in an oven at 80°C for 24 hours;

[0037] S2, uniformly mixing the dried conductive carbon black and the additive; after uniform mixing, no aggregation of the conductive carbon black or the additive is visible to the naked eye, to obtain a conductive carbon black pre-treated product;

[0038] S3, melt-blending and extruding the conductive carbon black pretreated product obtained in step S2 and the polyethylene resin in a torque rheometer, and pelletizing after compression; the melt-blending and extrusion temperature is 150° C. and the rotation speed is 50 r / min;

[0039] S4, drying the mixture obtained in step S3, the oven temperature is constant at 60°C, and the drying time is 24h;

[0040] S5. The product obtained in step S4 is a thermoplastic polyethylene-based semi-conductive shielding material.

[0041] Example 2

[0042] A thermoplastic polyethylene-based semiconductive shielding material, which is different from Example 1 in that it comprises the following components in parts by weight: 71.5 parts of polyethylene resin; 25 parts of conductive carbon black; and 3.5 parts of additives, a total of 100 parts.

[0043] Comparative Example 1

[0044] A thermoplastic polyethylene-based semiconductive shielding material, which is different from Example 1 in that the polyethylene resin is a nonlinear low-density polyethylene having a melt index of 0.2 g / 10 min at 190° C. / 2.16 kg;

[0045] Comparative Example 2

[0046] A thermoplastic polyethylene-based semiconductive shielding material, which is different from Example 1 in that the polyethylene resin is high-density polyethylene, and the melt index at 190°C / 2.16kg is 0.2g / 10min;

[0047] Comparative Example 3

[0048] A thermoplastic polyethylene-based semiconductive shielding material, which is different from Example 1 in that the polyethylene resin is a linear low-density polyethylene having a melt index of 3 g / 10 min at 190° C. / 2.16 kg;

[0049] Comparative Example 4

[0050] A thermoplastic polyethylene-based semiconductive shielding material, which is different from Example 1 in that the conductive carbon black has a DBP absorption value of 200 ml / 100 g and an ash content of <0.1%;

[0051] Comparative Example 5

[0052] A thermoplastic polyethylene-based semiconductive shielding material, which is different from Example 1 in that it comprises the following components in parts by weight: 76.5 parts of polyethylene resin; 20 parts of conductive carbon black; and 3.5 parts of an auxiliary agent, a total of 100 parts.

[0053] Comparative Example 6

[0054] A thermoplastic polyethylene-based semiconductive shielding material, which is different from Example 1 in that it comprises the following components in parts by weight: 66.5 parts of polyethylene resin; 35 parts of conductive carbon black; and 3.5 parts of an auxiliary agent, a total of 100 parts.

[0055] Unless otherwise specified, the components and raw materials used in the embodiments 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.

[0056] Performance Testing

[0057] The properties of the thermoplastic polyethylene-based semiconductive shielding materials prepared in the above examples and comparative examples were tested, and the specific test items and test methods are as follows:

[0058] 1. Volume resistivity: tested by four-electrode system, refer to GB / T 1551-2009.

[0059] 2. Tensile properties: tested according to the method in the standard "GB / T 1040.2-2006". At room temperature (25±5℃), stretch at a speed of 100mm / min until it breaks, and record the tensile strength (MPa) and elongation at break (%).

[0060] 3. Melting point test: Using a differential scanning calorimeter (model: Swiss METTLER DSC822e), the temperature was raised from 30°C to 200°C at a heating rate of 10°C / min to obtain the melting peak temperature of the material, which was taken as the melting point of the material.

[0061] The test results are shown in Table 1.

[0062] Table 1

[0063]

[0064]

[0065] It can be seen from Examples 1-2 in Table 1 that the thermoplastic polyethylene-based semiconductive shielding material prepared by the present invention exhibits excellent mechanical properties and electrical properties.

[0066] It can be concluded from Comparative Examples 1-3 that the use of polyethylene of a specific type and melt index as the matrix resin of the semi-conductive shielding material can make the conductive carbon black in the material more evenly distributed and have more excellent mechanical properties.

[0067] From Comparative Examples 4-6, it can be concluded that adding a specific amount of conductive carbon black with a specific DCP value to a semi-conductive shielding material can make the carbon black content in the shielding material near the percolation threshold, and have excellent mechanical properties while having good electrical properties. In Comparative Example 5, the polyethylene resin content is too much, and only 20% of the conductive carbon black filler is added. The conductive network has not been fully established, and the distance between the conductive carbon blacks is large, resulting in a high volume resistivity of the composite material.

[0068] The melting point of the non-crosslinked polyethylene insulating material is 127.9°C. According to Examples 1-2 in Table 1, the melting point of the thermoplastic polyethylene-based semiconductive shielding material prepared by using a specified type of polyethylene in the present invention is close to the melting point of the thermoplastic insulating material. In general, the thermoplastic polyethylene-based semiconductive shielding material prepared by the present invention has excellent mechanical properties and electrical properties.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A thermoplastic polyethylene-based semi-conductive shielding material, characterized in that: The composition comprises the following components in parts by weight: Polyethylene resin 65-74 parts; conductive carbon black 20-30 parts; additives 2-6 parts; The polyethylene resin is a linear low-density polyethylene, and the melt index of the polyethylene resin at 190° C. / 2.16 kg is 0.15-0.25 g / 10 min.

2. The thermoplastic polyethylene-based semiconductive shielding material according to claim 1, characterized in that: The DBP absorption value of the conductive carbon black is 160-180 ml / 100 g, and the ash content is less than 0.1%.

3. The thermoplastic polyethylene-based semiconductive shielding material according to claim 1, characterized in that: The thermoplastic polyethylene-based semiconductive shielding material comprises the following components in parts by weight: Polyethylene resin 66.5-71.5 parts; conductive carbon black 25-30 parts; additives 3.5 parts.

4. The thermoplastic polyethylene-based semiconductive shielding material according to claim 1, characterized in that: The auxiliary agent includes 0.5-1 parts of antioxidant and 2-4 parts of dispersant.

5. The thermoplastic polyethylene-based semiconductive shielding material according to claim 4, characterized in that: The antioxidant includes at least one of the antioxidant 300 , the antioxidant 1010 , and the antioxidant 168 .

6. The thermoplastic polyethylene-based semiconductive shielding material according to claim 4, characterized in that: The dispersant includes at least one of white oil, ethylene bisstearamide and oleamide.

7. The method for preparing the thermoplastic polyethylene-based semiconductive shielding material according to any one of claims 1 to 6, characterized in that: The following steps are involved: The polyethylene resin, conductive carbon black and additives are mixed evenly according to a proportion, and then melt-blended and extruded in an extruder. After compression, pelletization and drying, a thermoplastic polyethylene-based semi-conductive shielding material is obtained.

8. The method for preparing the thermoplastic polyethylene-based semiconductive shielding material according to claim 7, characterized in that: The temperature of the melt blending extrusion is 150-180° C. and the rotation speed is 40-50 r / min.

9. The method for preparing the thermoplastic polyethylene-based semiconductive shielding material according to claim 7, characterized in that: The drying temperature is 60-80° C., and the drying time is 20-24 hours.

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