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

Abstract

The present application relates to the preparation method of the glycidyl ether containing acetophenone 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 acetophenone and DCP double crosslinking EAA and LDPE cable material in the present application is that: ethylene acrylic acid copolymer (EAA) and low density polyethylene (LDPE) are used as matrix, small molecule epoxy compound 5-acetyl resorcinol diglycidyl ether and DCP are used as crosslinking agent, and double crosslinking type high voltage direct current cable material is obtained on a flat curing machine by heating and pressurizing. The preparation method of the double crosslinking type high voltage direct current cable material prepared in 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 benzeneacetone-containing glycidyl ether and DCP double-crosslinking EAA and LDPE cable material and belongs to the technical field of high-voltage direct-current cable material preparation. BACKGROUND

[0002] At present, cable materials at home and abroad are all composed of low-density polyethylene and various stabilizers, antioxidants and other additives. The mechanical properties and thermal properties of the low-density polyethylene are poor, and the mechanical properties can be enhanced only by adding a free radical crosslinking agent DCP to generate crosslinked low-density polyethylene (XLPE). XLPE will accumulate a large amount of space charge under the continuous action of a high direct-current electric field, seriously distorts the electric field distribution in the cable insulation material, and directly affects the cable withstand voltage and service life. Adding a proper voltage stabilizer to XLPE can effectively inhibit space charge, and aromatic ketone compounds are reported to be the most effective voltage stabilizer. It is reported in the literature that the addition of benzeneacetone can increase the direct-current breakdown voltage by 30.4% (Jiang Chen et al., Research Progress of Voltage Stabilizers for Inhibiting Electrical Treeing in Cable Insulation Materials, Insulating Materials, 2018, 51(7)). Therefore, adding benzeneacetone derivatives with specific functional groups is a feasible direction for improving the insulation performance of high-voltage AC / DC cable XLPE insulation materials. However, long alkyl chains are usually introduced into the structure of benzeneacetone or benzeneacetone is introduced into XLPE in a grafted manner at present, which may cause problems such as migration, phase separation or unquantifiable grafting amount, so that the voltage stabilizer has not been commercialized.

[0003] The application is prepared by crosslinking reaction of EAA and diglycidyl ether containing benzeneacetone structural unit, so that the benzeneacetone structural fragment is introduced into the EAA molecule in equivalent, and the free radical crosslinking agent DCP is used to crosslink LDPE and EAA by free radical crosslinking, thereby improving the voltage grade of the cable material. The method not only quantitatively introduces benzeneacetone into the insulation material, but also quantitatively introduces benzeneacetone into the high molecular chain of polyolefin by direct nucleophilic addition reaction of benzeneacetone and crosslinking agent diglycidyl ether in a Click chemistry manner, thereby effectively avoiding the problems of migration and phase separation. SUMMARY

[0004] The preparation method of the benzeneacetone-containing glycidyl ether and DCP double-crosslinking EAA and LDPE cable material is characterized in that a certain amount of low-density polyethylene LDPE, a small molecule 5-acetyl resorcinol diglycidyl ether, an ethylene acrylic acid copolymer EAA and a dicumyl peroxide DCP are added into a torque rheometer for melt blending to obtain a mixed material; the mixed material is pressed and formed in a flat vulcanizing machine, and then crosslinked after being heated, so that a high-voltage direct-current cable material with significantly improved tensile strength is obtained.

[0005] Further, the DCP is used in an amount of 2.0% by mass of the LDPE, and the 5-acetylresorcinol diglycidyl ether / EAA / LDPE blend material has a mass comprising 1.0%-9.0% by mass of EAA, 91%-98% by mass of LDPE, and 0.2%-1.0% by mass of 5-acetylresorcinol diglycidyl ether.

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

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

[0008] S2, processing and molding; pressing and molding the blended composite material in a flat vulcanizing machine, then pressure crosslinking, and after cooling, placing it in vacuum drying treatment to obtain a high-voltage insulating cable material LEAD.

[0009] Further limitation, S1 specifically is: adding LDPE into a torque rheometer, melting at 115℃, the rotation speed is 60r / min, after mixing for 5min, adding EAA and epoxy compound 5-acetylresorcinol diglycidyl ether to continue mixing for 10min, and finally adding DCP to mix for 3min to obtain the blended composite material.

[0010] Further limitation, the pressing and molding temperature in S2 is 115℃, and the pressure is 15MPa.

[0011] Further limitation, the pressure crosslinking temperature in S2 is 175℃, and the pressure is 15MPa.

[0012] Further limitation, the vacuum drying treatment temperature in S2 is 80℃, and the time is 24h.

[0013] The second purpose of the present application is to provide an application of the composite material, and 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 acetophenone type, which can crosslink with polymers containing carboxyl groups, and combines with XLPE to construct a double crosslinking system, which significantly improves the mechanical tensile properties of the material.

[0016] (2) The acetophenone structure capable of effectively "trapping" electrons is integrated into the cable material through crosslinking, and an electron deep trap is introduced at the same time, which significantly enhances the direct-current breakdown performance of the high-voltage direct-current cable material.

[0017] (3) The LEAD composite insulating material prepared by the method has simple preparation process, low cost, and easy-to-obtain material, and has industrial production prospect. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 A thermal elongation rate diagram of the LEAD high-voltage direct-current cable material provided for different embodiments;

[0019] Figure 2 A tensile test result curve of the LEAD high-voltage direct-current cable material provided for different embodiments;

[0020] Figure 3 A Weibull distribution diagram of the DC breakdown field strength of the LEAD high-voltage direct-current cable material provided for different embodiments,

[0021] Figure 4 A conductive current characteristic curve of the LEAD high-voltage direct-current cable material provided for different embodiments; DETAILED DESCRIPTION

[0022] The experimental methods used in the following examples are all conventional methods unless otherwise specified. The materials, reagents, methods and instruments used are all conventional materials, reagents, methods and instruments in the art unless otherwise specified, and can be obtained by commercial channels by those skilled in the art.

[0023] Example 1:

[0024] The process of preparing the DCP / epoxy / LDPE / EAA modified composite material in this example is as follows:

[0025] Example 1:

[0026] (1) Melt blending: 35 g of LDPE was added to a torque rheometer and melted at 115°C with a rotation speed of 60 r / min. After mixing for 5 min, 0.7 g of EAA and 0.1 g of epoxy compound 5-acetyl resorcinol diglycidyl ether were added and mixed for another 10 min. Finally, 0.7 g of DCP was added and mixed for 3 min to obtain the blended composite material.

[0027] (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 for pressing and molding. Then, the material was crosslinked by pressing at a temperature of 175°C and a pressure of 15 MPa for 30 min to obtain the LE 1.17 AD 2.0 high-voltage direct-current cable material.

[0028] Example 2:

[0029] (1) melt blending: 35 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, 1.4 g EAA and 0.21 g epoxy compound 5-acetyl resorcinol diglycidyl ether were added and mixed for another 10 min, finally 0.7 g DCP was added and mixed for 3 min to obtain the blended composite material.

[0030] (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 LE 3.82 AD 2.0 High-voltage direct-current cable material.

[0031] Example 3

[0032] (1) melt blending: 35 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, 1.4 g EAA and 0.21 g epoxy compound 5-acetyl resorcinol diglycidyl ether were added and mixed for another 10 min, finally 0.7 g DCP was added and mixed for 3 min to obtain the blended composite material.

[0033] (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 LE 5.61 AD 2.0 High-voltage direct-current cable material.

[0034] Example 4:

[0035] ((1) melt blending: 35 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, 1.4 g EAA and 0.21 g epoxy compound 5-acetyl resorcinol diglycidyl ether were added and mixed for another 10 min, finally 0.7 g DCP was added and mixed for 3 min to obtain the blended composite material.

[0036] (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 LE 8.13 AD 2.0 High-voltage direct-current cable material.

[0037] The different content of acetophenone type small molecule epoxy compounds and DCP double crosslinking XLPE high voltage direct current cable materials prepared in the above embodiments 1-4 were tested for performance, and the specific test results are as follows:

[0038] (1) Prepare dumbbell test pieces and measure the cross-sectional area according to the test method specified in GB / T 2951.11-2008, cut the prepared modified high voltage direct current cable material sample into a dumbbell-shaped sample with a thickness of 1 mm, the total length is 75 mm, the effective test part width is 4±0.2 mm, the surface is smooth and free of visible defects, and mark the mark line with 20 mm interval on the narrow section using a marker. In a 200℃ natural ventilation oven, the test piece is hung down from the upper clamp, clamped with the lower clamp, and a weight is added to the lower clamp, the weight = 20.4 x test piece thickness x test piece width (including clamp, support rod and weight), the test piece is kept in the oven at 200℃, after 15 minutes, the distance between the mark lines is measured and the elongation is calculated.

[0039] According to the requirements of GB / T12527-2008, the thermal elongation of XLPE of the insulating cable should not be higher than 175%. It can be seen from Figure 1 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, and when the EAA content is 8.13%, the elongation is only 68.5%.

[0040] (2) The above 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, the total length was 75 mm, the effective test part width was 4±0.2 mm, the surface was smooth and free of visible defects, and the mark line was marked on the narrow section with a marker with 20 mm interval. The clamp distance was set to 20 mm, the tensile speed was 250 mm / min, and each material was tested 5 times.

[0041] According to 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. From Figure 2 it can be seen 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 1343.09%, the tensile strength reaches 26.08 MPa, the elongation at break is increased by 6.71 times compared with the standard, and the tensile strength is increased by 2.08 times compared with the standard.

[0042] (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.

[0043] The two-parameter Weibull distribution is used to perform statistics on the DC breakdown strength experimental data, which is described as follows:

[0044] P(E)=1-exp(-(E / E b ) β )

[0045] 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.

[0046] The Weibull distribution of DC breakdown strength of the above four materials is as follows: Figure 3 shown.

[0047] Depend on Figure 3 It can be seen that the DC breakdown strength of the four modified high-voltage DC cable materials is improved to varying degrees compared to the original materials. After the addition of epoxy compounds, the breakdown strength of each content is significantly improved. 3.82 AD 2.0 The breakdown strength reaches a maximum of 381kV / mm, which is 25.99% higher than that of pure LDPE. This content shows that the high-voltage DC cable material has excellent breakdown characteristics.

[0048] (5) According to the electric field strength and temperature of the insulation layer of the high-voltage DC cable during operation, the above four materials are tested for conductivity and current of 200 μm samples at a field strength of 5 kV to 35 kV within the cable operating temperature range of 30 ° C to obtain their EJ curves, as shown in Figure 2. Figure 4 As shown, the polarization time was set to 165 min.

[0049] Depend on Figure 4 It can be seen that the conductivity of the modified high-voltage DC cable material is reduced to 8.26×10 -12 S / m, which indicates that the introduced traps suppress the free movement of charges, which improves the electrical insulation of the HVDC cable material.

[0050] The above merely describes preferred embodiments of the present application, and the skilled in the art can make appropriate changes and modifications to the above embodiments, and the present application is not limited to the above specific embodiments. Some modifications and changes of the present application should fall within the protection scope of the claims of the present application.

Claims

1. A method for preparing a double cross-linked EAA and LDPE cable material containing glycidyl ether of acetophenone and DCP, characterized in that A certain amount of low-density polyethylene (LDPE), 5-acetylresorcinol diglycidyl ether, ethylene acrylic acid copolymer (EAA), and dicumyl peroxide (DCP) were melt-blended in a torque rheometer to obtain a mixed material; the mixed material was press-formed in a flat-plate vulcanizer, then heated and cross-linked, and cooled to obtain a high-voltage DC cable material with significantly improved breakdown strength and tensile strength. LDPE accounts for 91%-98% of the mass of the blend of 5-acetylresorcinol diglycidyl ether, EAA, and LDPE; EAA accounts for 1.0%-9.0% of the mass of the blend of 5-acetylresorcinol diglycidyl ether, EAA, and LDPE; 5-acetylresorcinol diglycidyl ether accounts for 0.2%-1.0% of the mass of the blended material of 5-acetylresorcinol diglycidyl ether, EAA and LDPE.

2. The method for preparing a double cross-linked EAA and LDPE cable material containing glycidyl ether of acetophenone and DCP according to claim 1, characterized in that The content of DCP is 2.0% of the mass of LDPE.

3. Application of double cross-linked EAA and LDPE cable materials containing glycidyl ether of acetophenone and DCP, characterized in that: Applicable to high-voltage direct current cable materials, the cable material is prepared by the preparation method according to any one of claims 1-2.

4. The use according to claim 3, characterized in that The thermal elongation of the high-voltage DC cable material is only 68.5%, the tensile elongation at break can reach 1058.21%-1343.09%, and the DC breakdown strength reaches 381kV / mm.

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