Process for the preparation of glycidyl ether and dcp dual crosslinked eaa and ldpe cable materials containing benzophenone

Abstract

The present application relates to the preparation method of the glycidyl ether containing benzophenone and DCP double crosslinking EAA and LDPE cable material, belongs to the high voltage direct current cable technical field. The preparation method of the glycidyl ether containing benzophenone and DCP double crosslinking EAA and LDPE cable material in the present application: with ethylene acrylic acid copolymer (EAA) and low density polyethylene (LDPE) as matrix, using small molecule epoxy compound 4,4'-dihydroxybenzophenone diglycidyl ether and DCP as crosslinking agent, obtains double crosslinking type high voltage direct current cable material on the flat curing machine by heating and pressurizing. The double crosslinking type high voltage direct current cable material prepared by the preparation method of the present application is simple, and the breakdown performance and tensile performance of the high voltage cable material are significantly improved.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of a glycidyl ether containing benzophenone and DCP double-crosslinked EAA and LDPE cable material and belongs to the technical field of high-voltage direct-current cable material preparation. BACKGROUND

[0002] At present, low-density polyethylene is mainly used as a main component to prepare an insulating cable material by adding stabilizers, antioxidants, crosslinking aids and various other aids. Since the mechanical property of low-density polyethylene is poor, in order to enhance the mechanical property of polyethylene, a traditional method is to add a crosslinking agent DCP to make the polyethylene crosslink, thereby forming crosslinked polyethylene (XLPE). However, the addition of DCP and the stabilizers, the crosslinking aids and other aids will cause defects in the material, thereby reducing the performance of the cable. In order to ensure the purity of the cable material, it is necessary to reduce the use of other aids under the premise of ensuring excellent performance of the polyethylene.

[0003] The application uses LDPE and EAA as a base resin, uses DCP and 4,4'-dihydroxybenzophenone diglycidyl ether as a double crosslinking agent, makes LDPE and EAA simultaneously undergo free radical crosslinking and nucleophilic addition crosslinking, and in-situ introduces a voltage stabilizing fragment and an electronic deep trap at the same time when the double crosslinking system is formed, thereby avoiding the addition of other small molecule aids and significantly improving the mechanical property and the electrical property of the cable material. SUMMARY

[0004] The preparation method of the glycidyl ether containing benzophenone and the DCP double-crosslinked EAA and LDPE cable material is characterized in that a certain amount of low-density polyethylene LDPE, small molecule 4,4'-dihydroxybenzophenone diglycidyl ether, ethylene acrylic acid copolymer EAA and dicumyl peroxide DCP are added into a torque rheometer for melt blending, a mixed material is obtained, the mixed material is pressed and formed in a flat plate curing machine, is crosslinked after being heated, and high-voltage direct-current cable material LEBD with significantly improved breakdown strength and tensile property is obtained after being cooled.

[0005] Further, the amount of the DCP is 1.6% of the mass of the LDPE, and the mass of the 4,4'-dihydroxybenzophenone diglycidyl ether / EAA / LDPE blended material comprises 5%-11% of EAA in mass fraction, 85%-94% of LDPE in mass fraction and 1.6%-3.8% of 4,4'-dihydroxybenzophenone diglycidyl ether in mass fraction.

[0006] One of the purposes of the application is to provide a preparation method of the composite material, and the method comprises the following steps:

[0007] S1, melt blending; the DCP / epoxy / EAA / LDPE composite insulating material is uniformly blended to obtain a blended composite material;

[0008] S2, processing molding; the blended composite material is pressed and molded in a flat plate vulcanizing machine, then pressure crosslinking, after cooling, placed in vacuum drying treatment, to obtain high-voltage insulation cable material LEBD.

[0009] Further limited, S1 is specifically: LDPE is added to the torque rheometer, melted at 115 DEG C, the rotation speed is 60r / min, after mixing for 5 min, EAA and epoxy compound 4,4'-dihydroxybenzophenone diglycidyl ether are added to continue mixing for 10 min, finally DCP is added to mix for 3 min to obtain the blended composite material.

[0010] Further limited, the pressing molding temperature in S2 is 115 DEG C, and the pressure is 15MPa.

[0011] Further limited, the pressure crosslinking temperature in S2 is 175 DEG C, and the pressure is 15MPa.

[0012] Further limited, the vacuum drying treatment temperature in S2 is 80 DEG C, and the time is 24h.

[0013] The second object of the present application is to provide an application of the above-mentioned composite material, specifically the composite material is used for manufacturing high-voltage direct current cables.

[0014] The present application has the following beneficial effects:

[0015] (1) The present application designs a small molecule epoxy compound of benzophenone type, which can crosslink with the polymer containing carboxyl and fuse with XLPE to form a double crosslinking system, which significantly improves the mechanical tensile properties of the material.

[0016] (2) The benzophenone structure capable of effectively "trapping" electrons is introduced into the cable material in a crosslinked manner, and an electron deep trap is introduced in situ at the same time, which significantly enhances the DC breakdown performance of the high-voltage direct current cable material.

[0017] (3) The LEBD composite insulation material prepared by the present application has simple preparation process, low cost, and the material is easy to obtain, which has industrial production prospect. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The infrared spectrum test chart of the LEBD high-voltage direct current cable material provided by different embodiments is shown in the following table:

[0019] Figure 2 The thermal elongation rate chart of the LEBD high-voltage direct current cable material provided by different embodiments is shown in the following table:

[0020] Figure 3 The tensile test result curve of the LEBD high-voltage direct current cable material provided by different embodiments is shown in the following table:

[0021] Figure 4 Different embodiments provide a Weibull plot of the DC breakdown field strength of LEBD HVDC cable materials; DETAILED DESCRIPTION

[0022] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, methods and instruments used are conventional materials, reagents, methods and instruments in the art unless otherwise specified, which are available to those skilled in the art through commercial channels.

[0023] The process of preparing the DCP / epoxy / LDPE / EAA modified composite material in this example is as follows:

[0024] Example 1

[0025] (1) Melt blending: 37.33 g of LDPE was added into a torque rheometer and melted at 115 °C with a rotation speed of 60 r / min. After 5 min of mixing, 2 g of EAA and 0.67 g of epoxy compound 4,4'-dihydroxybenzophenone diglycidyl ether were added and mixed for another 10 min. Finally, 0.59 g of DCP was added and mixed for 3 min to obtain the blended composite material, wherein the EAA content was 5%.

[0026] (2) Processing and molding: the blended composite material was placed in a flat vulcanizing machine at a temperature of 115 °C and a pressure of 15 MPa for compression molding. Then, the crosslinking was completed under the conditions of a temperature of 175 °C and a pressure of 15 MPa for 30 min to obtain LE5BD 1.6 HVDC cable material.

[0027] Example 2

[0028] (1) Melt blending: 36.25 g of LDPE was added into a torque rheometer and melted at 115 °C with a rotation speed of 60 r / min. After 5 min of mixing, 2.8 g of EAA and 0.95 g of epoxy compound 4,4'-dihydroxybenzophenone diglycidyl ether were added and mixed for another 10 min. Finally, 0.58 g of DCP was added and mixed for 3 min to obtain the blended composite material, wherein the EAA content was 7%.

[0029] (2) Processing and molding: the blended composite material was placed in a flat vulcanizing machine at a temperature of 115 °C and a pressure of 15 MPa for compression molding. Then, the crosslinking was completed under the conditions of a temperature of 175 °C and a pressure of 15 MPa for 30 min to obtain LE7BD 1.6 HVDC cable material.

[0030] Example 3

[0031] (1) melt blending: 34.11 g LDPE was added into a torque rheometer and melted at 115 °C with a rotation speed of 60 r / min, after mixing for 5 min, 4.4 g EAA and 1.49 g epoxy compound 4,4'-dihydroxybenzophenone diglycidyl ether were added and mixed for another 10 min, finally 0.54 g DCP was added and mixed for 3 min to obtain the blended composite material, wherein the content of EAA was 11%.

[0032] (2) processing and molding: the blended composite material was placed in a flat vulcanizing machine with a temperature of 115 °C and a pressure of 15 MPa to be pressed and molded, and then cross-linked under the condition of a temperature of 175 °C and a pressure of 15 MPa for 30 min to obtain LE9BD 1.6 high-voltage direct-current cable material.

[0033] Example 4:

[0034] (1) melt blending: 34.11 g LDPE was added into a torque rheometer and melted at 115 °C with a rotation speed of 60 r / min, after mixing for 5 min, 4.4 g EAA and 1.49 g epoxy compound 4,4'-dihydroxybenzophenone diglycidyl ether were added and mixed for another 10 min, finally 0.54 g DCP was added and mixed for 3 min to obtain the blended composite material, wherein the content of EAA was 11%.

[0035] (2) processing and molding: the blended composite material was placed in a flat vulcanizing machine with a temperature of 115 °C and a pressure of 15 MPa to be pressed and molded, and then cross-linked under the condition of a temperature of 175 °C and a pressure of 15 MPa for 30 min to obtain LE 11 BD 1.6 high-voltage direct-current cable material.

[0036] Example 5:

[0037] (1) melt blending: 34.11 g LDPE was added into a torque rheometer and melted at 115 °C with a rotation speed of 60 r / min, after mixing for 5 min, 4.4 g EAA and 1.49 g epoxy compound 4,4'-dihydroxybenzophenone diglycidyl ether were added and mixed for another 10 min, finally 0.54 g DCP was added and mixed for 3 min to obtain the blended composite material, wherein the content of EAA was 11%.

[0038] (2) processing and molding: the blended composite material was placed in a flat vulcanizing machine with a temperature of 115 °C and a pressure of 15 MPa to be pressed and molded, and then cross-linked under the condition of a temperature of 175 °C and a pressure of 15 MPa for 30 min to obtain LE

[0039] Example 6:

[0040] (1) Melt blending: 35.18 g of LDPE was added into a torque rheometer and melted at 115 °C with a rotation speed of 60 r / min. After mixing for 5 min, 3.6 g of EAA and 1.22 g of epoxy compound 4,4'-dihydroxybenzophenone diglycidyl ether were added and mixed for another 10 min to obtain the blended composite material. The content of EAA was 9%.

[0041] (2) Processing and molding: the blended composite material was placed in a flat vulcanizing machine at a temperature of 115 °C and a pressure of 15 MPa for compression molding, and then crosslinked at a temperature of 110 °C and a pressure of 15 MPa for 30 min to obtain the LE9B high-voltage direct-current cable material.

[0042] Example 7:

[0043] (1) Melt blending: 36.4 g of LDPE was added into a torque rheometer and melted at 115 °C with a rotation speed of 60 r / min. After mixing for 5 min, 3.6 g of EAA was added and mixed for another 10 min, and finally 0.58 g of DCP was added and mixed for 3 min to obtain the blended composite material. The content of EAA was 9%.

[0044] (2) Processing and molding: the blended composite material was placed in a flat vulcanizing machine at a temperature of 115 °C and a pressure of 15 MPa for compression molding, and then crosslinked at a temperature of 175 °C and a pressure of 15 MPa for 30 min to obtain the LE9D 1.6 high-voltage direct-current cable material.

[0045] The different content of benzophenone type small molecule epoxy compounds and DCP double crosslinking XLPE high-voltage direct-current cable materials prepared in the above Examples 1-4 were tested for performance, and the specific test results are as follows:

[0046] (1) The molecular structure of the above materials was tested, analyzed and characterized by Fourier infrared spectrometer (FT / IR 6100) to verify whether it successfully participated in the crosslinking reaction. The thickness of the selected sample was 100 μm, the spectral wave number range was 500-4000 cm -1 , the scanning accuracy was 2 cm -1 , and the scanning number was 30 times, and the results are shown in Figure 1 .

[0047] As can be seen from Figure 1 , compared with the EAA / LDPE blended material, the modified high-voltage direct-current cable material has a new absorption peak near 3487 cm -1 , which corresponds to the absorption peak of the hydroxyl group in the composite material, and the sharp peak at 1700 cm -1 is red shifted to 1725 cm -1and became wide peak, corresponding to the characteristic peak of ester group in the composite material, indicating that the crosslinking was successful.

[0048] (2) The dumbbell test piece was prepared according to the test method specified in GB / T 2951.11-2008, and the cross-sectional area was measured. The prepared modified high-voltage direct-current cable material sample was cut into a dumbbell-shaped sample with a thickness of 1 mm, a total length of 75 mm, and an effective test part width of 4±0.2 mm. The surface was smooth and free of visible defects, and the marking line with a spacing of 20 mm was marked on the narrow section using a marker. The test was carried out in a 200℃ natural draft oven. The test piece was hung from the upper clamp, clamped with the lower clamp, and a weight was added to the lower clamp. The weight = 20.4 x thickness of test piece x width of test piece (including clamp, support rod and weight). The test piece was kept in the oven at 200℃ for 15 minutes. Then the distance between the marking lines was measured and the elongation was calculated.

[0049] According to the requirements specified in GB / T 12527-2008, the thermal elongation of XLPE of the insulating cable should not be higher than 175%. It can be seen from Figure 2 that the cable materials prepared by the present application all meet the standard requirements, and the thermal elongation decreases significantly with the increase of EAA. When the content of EAA is 11%, the thermal elongation is only 33.8%.

[0050] (3) The above four materials were tested according to the national standard GB / T528-2009 by SUNS UTM2203 electronic universal testing machine. According to the test method required in the standard, the prepared modified DCP / epoxy / EAA / LDPE composite material sample was cut into a dumbbell-shaped sample with a thickness of 1 mm, a total length of 75 mm, and an effective test part width of 4±0.2 mm. The surface was smooth and free of visible defects, and the marking line with a spacing of 20 mm was marked on the narrow section using a marker. The clamp distance was set to 20 mm, the tensile speed was 250 mm / min, and each material was tested 5 times.

[0051] According to the requirements of the standard GB / T22078.1-2008, the tensile strength and elongation at break of XLPE material for high-voltage power cable should be not less than 12.5 MPa and 200%, respectively. It can be seen from Figure 3 that under the same experimental conditions, the tensile properties of the modified high-voltage direct-current cable material are significantly improved. The elongation at break reaches 1382.24%, and the tensile strength reaches 31.06 MPa. The elongation at break is increased by 6.91 times compared with the standard, and the tensile strength is increased by 2.48 times compared with the standard.

[0052] (4) The DC breakdown field strength test of the above materials was conducted at 30°C using a cylindrical electrode, with a voltage ramp rate of 1 kV / s and a sample thickness of 50 μm. The sample and electrode were immersed in transformer oil throughout the entire process. Ten groups of samples were selected for repeated testing under each experimental condition.

[0053] The two-parameter Weibull distribution is used to perform statistics on the DC breakdown strength experimental data, which is described as follows:

[0054] P(E)=1-exp(-(E / E b ) β )

[0055] Where: P(E) is the cumulative failure probability, E is the measured breakdown field strength, E b is the characteristic breakdown field strength when the breakdown probability is 63.2%, and β is the shape parameter.

[0056] The Weibull distribution of DC breakdown strength of the above four materials is as follows: Figure 4 shown.

[0057] Depend on Figure 4 It can be seen that the DC breakdown strength of the four modified high-voltage DC cable materials has been improved to varying degrees compared to the unmodified ones. After adding epoxy compounds for modification, the breakdown field strength of each content is significantly improved. Compared with the unmodified ones, the breakdown strength of the modified high-voltage DC cable material reaches a maximum of 430kV / mm at 9% EAA content, which is higher than that of pure LDPE, LE9, and LE9D. 1.6 The four blank components of LE9B increased by 42.33%, 23.57%, 5.31% and 13.32% respectively. The high-voltage DC cable material with this content has good breakdown characteristics.

[0058] The above description is merely a preferred embodiment of the present invention. Given that those skilled in the art can make appropriate changes and modifications to the above embodiments, the present invention is not limited to the specific embodiments described above. Some modifications and changes to the present invention should also fall within the scope of protection of the claims of the present invention.

Claims

1. Process for the preparation of a benzophenone-containing glycidyl ether and DCP dual crosslinking EAA and LDPE cable material, characterized in that A certain amount of low-density polyethylene (LDPE) is melt-blended with 4,4'-dihydroxybenzophenone diglycidyl ether, ethylene acrylic acid copolymer (EAA) and dicumyl peroxide (DCP) in a torque rheometer to obtain a mixed material; the mixed material is pressed into a sheet in a flat vulcanizing machine, and then crosslinked by heating, to obtain a high-voltage direct-current cable material with significantly improved breakdown strength and tensile strength; The EAA accounts for 5%-11% of the total mass of 4,4'-dihydroxybenzophenone diglycidyl ether / EAA / LDPE; The LDPE accounts for 85%-94% of the total mass of 4,4'-dihydroxybenzophenone diglycidyl ether / EAA / LDPE; The content of DCP is 1.6% of the mass of LDPE; The 4,4'-dihydroxybenzophenone diglycidyl ether accounts for 1.6%-3.8% of the total mass of 4,4'-dihydroxybenzophenone diglycidyl ether / EAA / LDPE.

2. The process for the preparation of the benzophenone containing glycidyl ether and DCP dual crosslinking EAA and LDPE cable material according to claim 1, characterized in that The high-voltage direct-current cable material is mainly used for high-voltage direct-current cable materials.

3. The method of claim 2, wherein The prepared high-voltage direct-current cable material has a direct-current breakdown strength of 430.4KV / mm and a tensile elongation at break of 1008.4%-1382.24%.

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