Insulating material and preparation method and application thereof

Abstract

The present invention relates to the field of insulating materials, and in particular to an insulating material and a preparation method and application thereof. The present invention provides an insulating material, comprising the following raw materials by weight: 60-90 parts of a polyolefin elastomer, 10-40 parts of a thermoplastic elastomer, 0.1-0.65 parts of an antioxidant, and 0.05-0.2 parts of a cross-linking agent; the polyolefin elastomer comprises an ethylene-octene copolymer; the thermoplastic elastomer comprises a hydrogenated styrene-butadiene block copolymer. The uniformity of the insulating material provided by the present invention is improved, and on the basis of maintaining the high temperature resistance of the polyolefin elastomer, the insulating performance and breakdown strength of the insulating material are improved, and the dielectric loss of the material is reduced.

Description

Technical Field

[0001] The present invention relates to the field of insulating materials, and in particular to an insulating material and a preparation method and application thereof. Background Art

[0002] With the development of my country's economy, electricity consumption has grown rapidly annually. As a key component of my country's urban power grids, power cables have also seen rapid growth. By the end of 2018, the length of transmission cable lines reached 28,000 kilometers, and the length of distribution cable lines reached 620,000 kilometers. Currently, the annual output value of distribution cable in my country is approximately 200 billion yuan, and continues to grow at a rate of 10% annually. Insulation materials account for approximately 20% of this output value, representing a huge market potential.

[0003] Compared with traditional thermosetting cross-linked polyethylene (XLPE) insulated cables, the insulated cables prepared using thermoplastic elastomers as the base material have higher mechanical strength, but poor insulation performance, low breakdown strength and large dielectric loss, which greatly limits their practical application. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defects of the insulated cables prepared in the prior art using thermoplastic elastomers as base materials, such as poor insulation performance, low breakdown strength and large dielectric loss, thereby providing an insulating material and its preparation method and application.

[0005] The present invention provides an insulating material, which comprises the following raw materials in parts by weight: 60-90 parts of a polyolefin elastomer, 10-40 parts of a thermoplastic elastomer, 0.1-0.65 parts of an antioxidant, and 0.05-0.2 parts of a cross-linking agent;

[0006] The polyolefin elastomer comprises ethylene-octene copolymer (POE);

[0007] The thermoplastic elastomer includes hydrogenated styrene-butadiene block copolymer (SEBS).

[0008] Preferably, the mass ratio of the polyolefin elastomer, thermoplastic elastomer, antioxidant and cross-linking agent is (80-90):(10-15):(0.2-0.35):(0.05-0.1).

[0009] Preferably, the antioxidant is composed of 0.1-0.5 parts of thiobisphenol antioxidant and 0.025-0.15 parts of phosphite antioxidant in parts by weight;

[0010] The melting point of the thiobisphenol antioxidant is 161-164°C, and the ash content is <300ppm; the melting point of the phosphite antioxidant is 183-187°C, and the ash content is <300ppm;

[0011] Preferably, the thiobisphenol antioxidant includes 4,4'-thiobis(6-tert-butyl-3-methylphenol), and the phosphite antioxidant includes tris(2,4-di-tert-butylphenyl)phosphite.

[0012] Preferably, the mass ratio of the thiobisphenol antioxidant to the phosphite antioxidant in the antioxidant is (3-7):1.

[0013] Optionally, the density of the phosphite antioxidant is 1-1.1 g / cm 3 .

[0014] Preferably, the polyolefin elastomer has a density of 0.87-0.93 g / cm 3 , molecular weight distribution is 5-11, melting point is 50-165℃, volume resistivity is 10 15 -10 18 Ω·cm;

[0015] Optionally, the polyolefin elastomer has a density of 0.92-0.93 g / cm 3 , molecular weight distribution is 5.5-5.9, melting point is 161-164℃, volume resistivity is 10 16 -10 18 Ω·cm;

[0016] Optionally, the polyolefin elastomer has a melt flow rate of 1.1-1.7 g / 10 min at 190° C. and a pressure of 2.16 kg, a brittle temperature of -60 to -30° C., and an elongation at break of 100-1000%.

[0017] Preferably, the brittle temperature of the thermoplastic elastomer is -70 to -60°C, the maximum operating temperature is 149°C, and the decomposition temperature in an oxygen atmosphere is 270-350°C.

[0018] Preferably, the crosslinking agent includes an organic peroxide crosslinking agent having a melting point of 41-42°C and a relative density of 1.00-1.6 g / cm 3 , purity ≥99.9%.

[0019] Preferably, the cross-linking agent comprises dicumyl peroxide.

[0020] The present invention also provides a method for preparing the above-mentioned insulating material, comprising the following steps: pre-mixing, blending, filtering, and granulating the raw materials according to a formula to obtain the insulating material.

[0021] Preferably, the premixing temperature in the premixing step is 30-40°C, the time is 1-3 minutes, and the speed is 80-150 r / min;

[0022] The blending is melt blending, the blending temperature is 140-200° C., and the blending speed is 200-250 r / min;

[0023] The filter used in the filtration process has a pore size of 500 mesh;

[0024] The granulation is water-cooled strand granulation.

[0025] Optionally, the blending and filtering processes are completed in a twin-screw extruder.

[0026] Optionally, the twin-screw extruder includes a blending section and a filtering section. The raw materials are blended in the blending section, filtered in the filtering section, and then extruded and granulated. The blending section can be divided into nine zones, namely zone 1 to zone 9, and the temperatures from zone 1 to zone 9 are 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 20 ...

[0027] The present invention also provides a use of the above-mentioned insulating material or the insulating material prepared by the above-mentioned preparation method in cable insulating materials.

[0028] The technical solution of the present invention has the following advantages:

[0029] The insulating material provided by the present invention comprises the following raw materials, measured by weight: 60-90 parts of a polyolefin elastomer, 10-40 parts of a thermoplastic elastomer, 0.1-0.65 parts of an antioxidant, and 0.05-0.2 parts of a cross-linking agent; the polyolefin elastomer comprises an ethylene-octene copolymer; and the thermoplastic elastomer comprises a hydrogenated styrene-butadiene block copolymer. The present invention utilizes the polyolefin elastomer ethylene-octene copolymer as a base material and the thermoplastic elastomer hydrogenated styrene-butadiene block copolymer as an auxiliary modifying component. The two cooperate with each other to form an interconductive network by controlling the ratio of the thermoplastic elastomer to the polyolefin elastomer, thereby improving the uniformity of the insulating material. While maintaining the high-temperature resistance of the polyolefin elastomer, the insulating material improves its insulation performance and breakdown strength and reduces the dielectric loss of the material.

[0030] Furthermore, the insulating material provided by the present invention has a low relative dielectric constant. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 Weibull distribution diagram of the breakdown strength of the insulating materials of Example 3 and Comparative Example 3;

[0033] Figure 2 The DSC spectra of three tests of the insulating material of Example 3 are as follows;

[0034] Figure 3 The DSC spectra of the insulating material of Comparative Example 3 were tested three times. DETAILED DESCRIPTION

[0035] The following examples are provided for a better understanding of the present invention and are not intended to limit the best mode of implementation. They do not limit the content and scope of protection of the present invention. Any product identical or similar to the present invention obtained by anyone under the guidance of the present invention or by combining the features of the present invention with other prior arts shall fall within the scope of protection of the present invention.

[0036] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in this field can be used. If the manufacturer of the reagents or instruments is not specified, they are all commercially available conventional reagents.

[0037] The twin-screw extruder used in the examples and comparative examples includes a blending section and a filtration section. The raw materials are blended in the blending section, filtered in the filtration section, and then extruded and granulated. The blending section can be divided into nine zones, namely zone 1 to zone 9, and the temperatures from zone 1 to zone 9 are 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 200°C, and 200°C, respectively.

[0038] The polyolefin elastomer used in the examples and comparative examples is ethylene-octene copolymer purchased from ExxonMobil Chemical Company, model number VM6202, and the density of the polyolefin elastomer is 0.87 g / cm 3 , molecular weight distribution is 5-11, melting point is 50℃, volume resistivity is 1.6×10 17 Ω·cm, melt flow rate under 2.16kg pressure at 190℃ is 1.7g / 10min, brittle temperature is -30℃, and elongation at break is 300%;

[0039] The thermoplastic elastomer used in the examples and comparative examples is a hydrogenated styrene-butadiene block copolymer purchased from Kuraray Co., Ltd. of Japan, model P2000, with a brittle temperature of -60°C, a maximum operating temperature of 149°C, and a decomposition temperature of 270°C in an oxygen atmosphere;

[0040] The thiobisphenol antioxidant used in the examples and comparative examples is 4,4'-thiobis(6-tert-butyl-3-methylphenol), purchased from Lianyungang Ningkang Chemical Co., Ltd., model number 300#, the thiobisphenol antioxidant has a melting point of 161-164°C and an ash content of 200 ppm;

[0041] The phosphite antioxidant used in the examples and comparative examples is tris (2.4-di-tert-butylphenyl) phosphite, purchased from Dongguan Zhenming Chemical Co., Ltd., model 168. The phosphite antioxidant has a melting point of 183-187 ° C and a density of 1.03 g / cm 3 , ash content is 200ppm;

[0042] The crosslinking agent used in the examples and comparative examples is dicumyl peroxide, purchased from Shanghai Kaiyin Chemical Co., Ltd., model DCP, with a melting point of 41-42 ° C and a relative density of 1.56 g / cm 3 , purity is 99.9%.

[0043] Example 1

[0044] The preparation process of the insulating material provided in this embodiment includes the following steps:

[0045] 70 kg of ethylene-octene copolymer, 30 kg of hydrogenated styrene-butadiene block copolymer, 0.1 kg of 4,4'-thiobis(6-tert-butyl-3-methylphenol), 0.025 kg of tris(2,4-di-tert-butylphenyl)phosphite and 0.1 kg of dicumyl peroxide are pre-mixed at 30°C at a speed of 150 r / min for 2 minutes, the pre-mixed materials are put into a twin-screw extruder and melt-blended from zone 1 to zone 9 at a speed of 200 r / min, the melt is filtered through a filter with a pore size of 500 mesh, extruded from a die, and then granulated by water-cooling to obtain the insulating material.

[0046] Example 2

[0047] The preparation process of the insulating material provided in this embodiment includes the following steps:

[0048] 80 kg of ethylene-octene copolymer, 20 kg of hydrogenated styrene-butadiene block copolymer, 0.2 kg of 4,4'-thiobis(6-tert-butyl-3-methylphenol), 0.03 kg of tris(2,4-di-tert-butylphenyl)phosphite and 0.1 kg of dicumyl peroxide are pre-mixed at 30°C at a speed of 150 r / min for 2 minutes, the pre-mixed materials are put into a twin-screw extruder and melt-blended from zone 1 to zone 9 at a speed of 200 r / min, the melt is filtered through a filter with a pore size of 500 mesh, extruded from a die, and then granulated by water-cooling to obtain the insulating material.

[0049] Example 3

[0050] The preparation process of the insulating material provided in this embodiment includes the following steps:

[0051] 90 kg of ethylene-octene copolymer, 10 kg of hydrogenated styrene-butadiene block copolymer, 0.3 kg of 4,4'-thiobis(6-tert-butyl-3-methylphenol), 0.05 kg of tris(2,4-di-tert-butylphenyl)phosphite and 0.1 kg of dicumyl peroxide are pre-mixed at 30°C at a speed of 150 r / min for 2 minutes, the pre-mixed materials are put into a twin-screw extruder and melt-blended from zone 1 to zone 9 at a speed of 200 r / min, the melt is filtered through a filter with a pore size of 500 mesh, extruded from a die, and then granulated by water-cooling to obtain the insulating material.

[0052] Example 4

[0053] The preparation process of the insulating material provided in this embodiment includes the following steps:

[0054] 90 kg of ethylene-octene copolymer, 10 kg of hydrogenated styrene-butadiene block copolymer, 0.4 kg of 4,4'-thiobis(6-tert-butyl-3-methylphenol), 0.1 kg of tris(2,4-di-tert-butylphenyl)phosphite and 0.1 kg of dicumyl peroxide are pre-mixed at 30°C at a speed of 150 r / min for 2 minutes, the pre-mixed materials are put into a twin-screw extruder and melt-blended from zone 1 to zone 9 at a speed of 200 r / min, the melt is filtered through a filter with a pore size of 500 mesh, extruded from a die head, and then granulated by water-cooling strands to obtain the insulating material.

[0055] Example 5

[0056] The preparation process of the insulating material provided in this embodiment includes the following steps:

[0057] 90 kg of ethylene-octene copolymer, 10 kg of hydrogenated styrene-butadiene block copolymer, 0.5 kg of 4,4'-thiobis(6-tert-butyl-3-methylphenol), 0.15 kg of tris(2,4-di-tert-butylphenyl)phosphite and 0.2 kg of dicumyl peroxide are pre-mixed at 30°C at a speed of 150 r / min for 2 minutes, the pre-mixed materials are put into a twin-screw extruder and melt-blended from zone 1 to zone 9 at a speed of 200 r / min, the melt is filtered through a filter with a pore size of 500 mesh, extruded from a die head, and then granulated by water-cooling strands to obtain the insulating material.

[0058] Comparative Example 1

[0059] The preparation process of the insulating material provided in this comparative example includes the following steps:

[0060] 100 kg of ethylene-octene copolymer, 0.08 kg of 4,4'-thiobis(6-tert-butyl-3-methylphenol), 0.18 kg of tris(2,4-di-tert-butylphenyl)phosphite and 0.1 kg of dicumyl peroxide were pre-mixed at 30°C at a speed of 150 r / min for 2 minutes, the pre-mixed materials were put into a twin-screw extruder and melt-blended from zone 1 to zone 9 at a speed of 200 r / min, the melt was filtered through a filter with a pore size of 500 mesh, extruded from a die, and then granulated by water-cooling to obtain the insulating material.

[0061] Comparative Example 2

[0062] The preparation process of the insulating material provided in this comparative example includes the following steps:

[0063] 100 kg of hydrogenated styrene-butadiene block copolymer, 0.05 kg of 4,4'-thiobis(6-tert-butyl-3-methylphenol), 0.2 kg of tris(2,4-di-tert-butylphenyl)phosphite and 0.1 kg of dicumyl peroxide are pre-mixed at 30°C at a speed of 150 r / min for 2 minutes, the pre-mixed materials are put into a twin-screw extruder and melt-blended from zone 1 to zone 9 at a speed of 200 r / min, the melt is filtered through a filter with a pore size of 500 mesh, extruded from a die, and then granulated by water-cooling to obtain the insulating material.

[0064] Comparative Example 3

[0065] The insulating material provided in this comparative example is high-voltage cross-linked polyethylene, domestically produced, model 110kV, produced by Zhejiang Wanma Polymer Materials Co., Ltd.

[0066] Test Case

[0067] The insulating materials obtained in the examples and comparative examples were hot-pressed using a flat-plate vulcanizer. The molding process involved pre-pressing the insulating materials at 200°C for 5 minutes, followed by pressing at 200°C and 15 MPa for 20 minutes. This produced circular thin sheets with a radius of 15 mm and a thickness of 0.2 mm. Dielectric and breakdown field strength tests were performed on the test samples.

[0068] The breakdown strength test was conducted using a sphere-to-sphere electrode with a diameter of 10 mm, in accordance with GB / T 1408.2-2006. At 25°C, a continuously increasing voltage method was used. At least 20 data points were measured for each test sample, and the Weibull distribution was used for analysis. The test results are shown in Table 1 (breakdown strength units are kV / mm).

[0069] Figure 1 3 is a Weibull distribution diagram of the breakdown strength of the insulating materials of Example 3 and Comparative Example 3.

[0070] The relative dielectric constant and dielectric loss tests were conducted at 25°C in accordance with the provisions of GB / T1409-2006. The measurement results of the relative dielectric constant and dielectric loss at 50 Hz are shown in Table 1.

[0071] The electrical conductivity of the materials was measured using a high-voltage DC power supply, a constant-temperature drying oven (shielded box), and a three-electrode test system. The measuring electrodes had a diameter of 15 cm. Quasi-steady-state current was measured using a Keithley 6517A ammeter with data logging software. The electrical conductivity of the insulating materials was tested at 25°C and a field strength of 5 kV / mm using a step-up voltage method. The sampling time for each sample was 3600 s. The test results for the insulating materials of the Examples and Comparative Examples are shown in Table 1.

[0072] The thermal stability of the insulating materials of Example 3 and Comparative Example 3 was analyzed by differential scanning calorimetry (DSC). Figure 2 The DSC spectra of three tests of the insulating material of Example 3 are as follows; Figure 3 The DSC spectra of the insulating material of Comparative Example 3 were tested three times.

[0073] Table 1

[0074]

[0075] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for preparing an insulating material, characterized in that: The steps include: 90 kg of ethylene-octene copolymer, 10 kg of hydrogenated styrene-butadiene block copolymer, 0.3 kg of 4,4'-thiobis(6-tert-butyl-3-methylphenol), 0.05 kg of tris(2.4-di-tert-butylphenyl)phosphite and 0.1 kg of diisopropylbenzene peroxide are premixed at 30° C. and 150 r / min for 2 min, and the premixed materials are put into a twin-screw extruder and melt-blended from zone 1 to zone 9 at 200 r / min. The melt is filtered through a filter with an aperture of 500 mesh and extruded from a die, and then granulated by water-cooling to obtain the insulating material.

2. Use of the insulating material prepared by the preparation method according to claim 1 in cable insulating materials.

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