Voltage-resistant monomer, preparation method of voltage-resistant monomer, direct-current breakdown-resistant low-density polyethylene and preparation method of direct-current breakdown-resistant low-density polyethylene

Abstract

The invention provides a voltage-resistant monomer and a preparation method thereof, and direct-current breakdown-resistant low-density polyethylene and a preparation method thereof. The voltage-resistant monomer has a structure as shown in a formula I or a formula II, the preparation raw materials are cheap and easy to obtain, the voltage-resistant monomer can be synthesized by a one-step method, the experimental conditions are simple, and the yield is relatively high. After a small amount of the voltage-resistant monomer and the low-density polyethylene are subjected to melt blending, a trap effect can be achieved, and high-energy electron energy can be dissipated, so that the high-voltage direct current breakdown resistance of the low-density polyethylene material is improved. Tests show that the direct current breakdown strength of the direct current breakdown resistant low-density polyethylene material provided by the invention is more than 340KV / mm, the highest direct current breakdown strength reaches 440KV / mm, and compared with the direct current breakdown strength of an unmodified original low-density polyethylene material, the direct current breakdown strength of the direct current breakdown resistant low-density polyethylene material provided by the invention is increased by more than 42KV / mm, and the highest direct current breakdown strength of the direct current breakdown resistant low-density polyethylene material is increased by about 150KV / mm.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of polyethylene, and particularly relates to a voltage-resistant monomer and a preparation method thereof, and a low-density polyethylene resistant to DC breakdown and a preparation method thereof. BACKGROUND

[0002] In recent years, polyethylene (PE for short) is widely used in the electrical field as a kind of thermoplastic resin due to its good electrical insulation, chemical stability, processing performance, water resistance and mechanical properties.

[0003] At present, polyethylene can be generally divided into high-density polyethylene (HDPE for short), medium-density polyethylene (MDPE for short) and low-density polyethylene (LDPE for short) according to different densities. The high-density polyethylene and the medium-density polyethylene have poor flexibility and cannot be applied to occasions requiring frequent bending or twisting in the electrical field, such as movable electrical equipment connecting lines. The low-density polyethylene has long-chain branching and short-chain branching on the main chain, has the advantages of low melting point, high flexibility and good processing performance, but its low DC breakdown strength limits its application in the electrical field.

[0004] To solve the problem, researchers generally use a crosslinking agent to initiate the crosslinking of LDPE to increase the molecular weight and improve the DC breakdown strength, or blend polystyrene (PS for short) into LDPE and dope some inorganic nanoparticles to improve the DC breakdown strength. However, the crosslinking of LDPE by adding a crosslinking agent results in crosslinked polyethylene (XLPE for short) which is neither melted nor dissolved and has no processing performance; the blending of PS and LDPE causes phase separation of PS and LDPE, and doping of nanoparticles results in an island structure, which greatly limits the mechanical properties of the modified material. SUMMARY

[0005] Therefore, the application aims to provide a voltage-resistant monomer and a preparation method thereof, and a low-density polyethylene resistant to DC breakdown and a preparation method thereof. The voltage-resistant monomer can be grafted onto the low-density polyethylene as a voltage-resistant monomer to improve the DC breakdown strength.

[0006] To achieve the above object, the application adopts the following technical solutions.

[0007] In a first aspect, the application provides a voltage-resistant monomer having the following structural formula I or formula II:

[0008]

[0009] wherein, R1 is selected from C2-C8 alkenyl with a double bond at the end; R2 is selected from hydrogen, C1-C6 alkyl, oxygen-containing group, or R2 and the carbon it is on form an aromatic ring with the adjacent carbon atom; R3 is selected from null, -O-, or -CO-; n = 1 or 2.

[0010] Preferably, R1 is selected from C2-C6 alkenyl with a double bond at the end.

[0011] Preferably, R2 is selected from hydrogen, C1-C4 alkyl, hydroxyl, aldehyde group, or R2 and the carbon it is on form a benzene ring with the adjacent carbon atom.

[0012] Preferably, when n = 2, the two -OR1 are located at the ortho position or the para position of the benzene ring, respectively.

[0013] More preferably, the voltage-resistant monomer is selected from any one of the following formulas M1-M7:

[0014]

[0015]

[0016] In a second aspect, the present application provides a method for preparing the voltage-resistant monomer described above, comprising the following steps:

[0017] performing etherification reaction on a phenolic compound represented by formula A and a halogenated hydrocarbon compound R1X in the presence of a basic substance to obtain a voltage-resistant monomer represented by formula I;

[0018] or

[0019] performing etherification reaction on a phenolic compound represented by formula B and a halogenated hydrocarbon compound R1X in the presence of a basic substance to obtain a voltage-resistant monomer represented by formula II; X in R1X is a halogen atom.

[0020]

[0021] Preferably, the etherification reaction is performed in an inert atmosphere.

[0022] Preferably, the basic substance comprises sodium hydroxide and / or potassium hydroxide.

[0023] Preferably, the phenolic compound represented by formula A is dissolved in a solution of the basic substance in batches, and after complete dissolution, the halogenated hydrocarbon compound R1X is added to perform etherification reaction.

[0024] Preferably, the solution of the basic substance is obtained by dissolving the basic substance in a solvent, and the solvent comprises any one or more of anhydrous ethanol, anhydrous DMF, anhydrous acetonitrile, or THF.

[0025] Preferably, said R1X is selected from any one or more of 7-bromo-1-heptene, 6-bromo-1-hexene, 5-iodo-1-pentene, 4-bromo-1-butene or 3-chloro-1-propene.

[0026] Preferably, the temperature of the etherification reaction is 50-120℃ and the time is 7-10h.

[0027] In a third aspect, the present application provides a low-density polyethylene with DC breakdown resistance, which is prepared from raw materials including: low-density polyethylene 99.0-99.8wt%, voltage-resistant monomer 0.2-1.0wt%.

[0028] The voltage-resistant monomer is the voltage-resistant monomer as described above.

[0029] Preferably, the Mw of the low-density polyethylene with DC breakdown resistance is 10.70*10 w 4 4 .

[0030] In a fourth aspect, the present application provides a preparation method of the low-density polyethylene with DC breakdown resistance, which includes the following steps:

[0031] The low-density polyethylene and the voltage-resistant monomer are melt-blended at 150-200℃ to obtain the low-density polyethylene with DC breakdown resistance.

[0032] Preferably, the time of the melt-blending is 8-15min.

[0033] Preferably, the melt-blending is performed in a torque rheometer, and the rotation speed of the torque rheometer is 60-120rpm.

[0034] Compared with the prior art, the present application has the following beneficial effects:

[0035] The present application provides a voltage-resistant monomer with the structure as shown in Formula I or Formula II, which is prepared from cheap and readily available raw materials, can be synthesized in one step, has simple experimental conditions and high yield. After a small amount of the voltage-resistant monomer is melt-blended with low-density polyethylene, the voltage-resistant monomer can play a trapping role and dissipate the energy of high-energy electrons, thereby improving the high-voltage DC breakdown resistance of the low-density polyethylene material. Tests show that the DC breakdown strength of the low-density polyethylene material with DC breakdown resistance in the present application is above 340KV / mm, and the highest is 440KV / mm; the DC breakdown strength of the low-density polyethylene material is increased by more than 42KV / mm, and the highest is increased by about 150KV / mm.

[0036] ​​Meanwhile, the preparation method of the low-density polyethylene with DC breakdown resistance in the present application only needs to melt blend the low-density polyethylene with the voltage-resistant monomer, without pre-irradiation, and without complicated pretreatment and processing process, and is simple in operation and low in cost. Meanwhile, the omission of the pre-irradiation step makes the preparation method not change the excellent processing performance, thermal performance and mechanical performance of the original low-density polyethylene material. DETAILED DESCRIPTION

[0037] The technical solutions of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0038] The present application provides a voltage-resistant monomer with the following structural formula I or II:

[0039]

[0040] wherein R1 is selected from C2-C8 alkenyl with double bond at the end (such as vinyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl or octenyl, etc.); R2 is selected from hydrogen, C1-C6 alkyl (such as methyl, ethyl, propyl, butyl, pentyl or hexyl, etc.), oxygen-containing group or R2 and the adjacent carbon atom form an aromatic ring; R3 is selected from null, -O- or -CO-; and n = 1 or 2.

[0041] In some embodiments of the present application, the voltage-resistant monomer has the structural formula I or II, wherein R1 is selected from C2-C6 alkenyl with double bond at the end; and R2 is selected from hydrogen, C1-C4 alkyl, hydroxyl, aldehyde group or R2 and the adjacent carbon atom form a benzene ring.

[0042] In some embodiments of the present application, the voltage-resistant monomer has the structural formula I, and when n = 2, the two -OR1 are located at the ortho position or para position of the benzene ring.

[0043] In some specific embodiments of the present application, the voltage-resistant monomer is selected from any one of the following formulae M1-M7:

[0044]

[0045]

[0046] The voltage-resistant monomer represented by the above-mentioned formula I or formula II is used in a small amount and is melt-blended with low-density polyethylene, thereby playing a trapping role and dissipating high-energy electron energy, so as to improve the high-voltage direct-current breakdown resistance of the low-density polyethylene material.

[0047] The application further provides a preparation method of the voltage-resistant monomer represented by the above-mentioned formula I, comprising the following steps:

[0048] The phenolic compound represented by formula A and the halogenated hydrocarbon compound R1X are subjected to etherification reaction in the presence of a basic substance, so as to obtain the voltage-resistant monomer represented by formula I.

[0049]

[0050] In the application, the R2 group in the phenolic compound represented by formula A is consistent with the R2 group in the compound represented by the above-mentioned formula I. The R1 group in the halogenated hydrocarbon compound R1X is consistent with the R1 group in the compound represented by the above-mentioned formula I. The X in the R1X is a halogen atom, which can be Cl, Br, I, etc. Specifically, the R1X is selected from any one or more of 7-bromo-1-heptene, 6-bromo-1-hexene, 5-iodo-1-pentene, 4-bromo-1-butene or 3-chloro-1-propene.

[0051] According to the application, the phenolic compound represented by formula A and the halogenated hydrocarbon compound R1X are subjected to etherification reaction in the presence of a basic substance, so as to obtain the voltage-resistant monomer represented by formula I.

[0052] In some embodiments of the application, the phenolic compound represented by formula A is preferably dissolved in a solution of a basic substance in batches (specifically, 5-10 times), after complete dissolution, the halogenated hydrocarbon compound R1X is added, and etherification reaction is carried out at 50-120℃ (such as 50℃, 60℃, 70℃, 80℃, 90℃, 100℃, 110℃ or 120℃, etc.) in an inert atmosphere, and the reaction time is 7-10h (such as 7h, 7.5h, 8h, 8.5h, 9h, 9.5h or 10h, etc.). The halogenated hydrocarbon compound R1X is excessive compared with the phenolic compound represented by formula A, so that the phenolic hydroxyl group is completely reacted. The inert atmosphere is well known to those skilled in the art, such as nitrogen.

[0053] The solution of the above-mentioned basic substance is preferably obtained by dissolving the basic substance in a solvent, the basic substance includes sodium hydroxide and / or potassium hydroxide, and the solvent includes any one or more of anhydrous ethanol, anhydrous DMF, anhydrous acetonitrile or THF, and the preferred solvent is anhydrous ethanol. In some preferred embodiments of the application, the solvent is preferably subjected to ultrasonic conditions under reduced pressure to remove oxygen in the solvent, so as to prevent the occurrence of oxidation side reactions.

[0054] After the etherification reaction is completed, the voltage-resistant monomer shown in the above Formula I is obtained.

[0055] In some preferred embodiments of the present application, after the etherification reaction is completed, purification treatment is preferably performed: the solution after the reaction is filtered under reduced pressure to remove halide salt therein, and then saturated alkaline solution is used to wash the product to remove the reactants, and the product is spin-dried after being separated.

[0056] In some specific embodiments of the present application, the phenolic compound shown in Formula A is hydroquinone, and the halogenated hydrocarbon compound R1X is 6-bromo-1-hexene, and the obtained compound structure is shown in Formula M3 as an example, and the preparation method comprises the following steps:

[0057] First, 500 mL of anhydrous ethanol is subjected to ultrasonic reduction under reduced pressure to remove oxygen dissolved in the anhydrous ethanol; then 2-4 g of potassium hydroxide is added to the anhydrous ethanol and dissolved at room temperature; after the potassium hydroxide is completely dissolved, 5 g of phenol is added in batches; after the phenol is completely dissolved, excess 6-bromo-1-hexene is added, heated to micro-boiling, and returned to the reflux device, and the reaction time is about 7-10 h, the reaction is a Williamson etherification reaction process, and the reaction route is as follows (the bromine in 6-bromo-1-hexene is converted into potassium bromide):

[0058]

[0059] After the etherification reaction is completed, purification is performed: the solution after the reaction is filtered under reduced pressure to remove potassium bromide therein, and then saturated potassium hydroxide solution is used to wash the product to remove the reactants, and the product is spin-dried after being separated.

[0060] The present application also provides a preparation method of the voltage-resistant monomer shown in the above Formula II, comprising the following steps:

[0061] The phenolic compound shown in Formula B and the halogenated hydrocarbon compound R1X are subjected to etherification reaction in the presence of an alkaline substance to obtain the compound shown in Formula II;

[0062]

[0063] In the present application, the R3 group in the phenolic compound shown in Formula B is consistent with the R3 group in the compound shown in the above Formula II. The R1 group in the halogenated hydrocarbon compound R1X is consistent with the R1 group in the compound shown in the above Formula II. The X in R1X is a halogen atom, which can be F, Cl, Br, I, etc.

[0064] It is explained that the preparation method of the voltage-resistant monomer shown in formula I and the preparation method of the voltage-resistant monomer shown in formula II are different only in the structure of the phenolic compound, and the conditions and parameters involved in the preparation method are consistent. Therefore, the preparation method of the voltage-resistant monomer shown in formula II can refer to the preparation method of the voltage-resistant monomer shown in formula I, which will not be repeated here.

[0065] The raw material for preparing the voltage-resistant monomer shown in formula I or formula II is cheap and easy to obtain, and can be synthesized by one-step method. The experimental conditions are simple, and the yield is high. The product obtained by the preparation method of the present application is detected by nuclear magnetic resonance hydrogen spectrum, and the yield is more than 60% and the product is relatively pure.

[0066] The present application also provides a low-density polyethylene resistant to DC breakdown (referred to as modified LDPF), which comprises: low-density polyethylene 99.0-99.8 wt%, voltage-resistant monomer (i.e., the compound shown in formula I or formula II) 0.2-1.0 wt%, such as low-density polyethylene 99.0 wt%, voltage-resistant monomer 1.0 wt%; low-density polyethylene 99.5 wt%, voltage-resistant monomer 0.5 wt%; low-density polyethylene 99.8 wt%, voltage-resistant monomer 0.2 wt%, etc. It can be seen that the amount of voltage-resistant monomer added in the low-density polyethylene resistant to DC breakdown in the present application is small.

[0067] It should be noted that too much voltage-resistant monomer will increase the production cost and is not practical, on the contrary, too low will result in no obvious modification effect. Therefore, the voltage-resistant monomer is preferably introduced according to the above proportion range.

[0068] In the present application, the M w is 10.70 x 10 4 -11.19 x 10 4 .

[0069] The present application also provides a preparation method of the low-density polyethylene resistant to DC breakdown, comprising the following steps:

[0070] The low-density polyethylene and the voltage-resistant monomer are melt blended to obtain the low-density polyethylene resistant to DC breakdown.

[0071] In the present application, the low-density polyethylene and the voltage-resistant monomer are preferably melt blended at 150-200 ℃ (such as 150 ℃, 160 ℃, 170 ℃, 180 ℃, 190 ℃ or 200 ℃, etc.) for 8-15 min (such as 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min or 15 min, etc.) to obtain the modified low-density polyethylene.

[0072] In some embodiments of the application, the melt blending is performed in a torque rheometer at a rotational speed of 60-120 rpm, such as 60 rpm, 80 rpm, 100 rpm or 120 rpm.

[0073] It has been tested that the DC breakdown strength of the low-density polyethylene material prepared according to the above method provided by the application is above 340 KV / mm, and the highest is up to 440 KV / mm, which is increased by above 42 KV / mm, and the highest is increased by about 150 KV / mm, compared with the DC breakdown strength of the original low-density polyethylene (abbreviation: original LDPF) material. It can be seen that the method provided by the application not only does not need to be pre-irradiated, so that the preparation method does not change the excellent processing performance, thermal performance and mechanical performance of the original low-density polyethylene material, but also can improve the DC breakdown strength of the DC breakdown resistant LDPF material.

[0074] In order to further illustrate the application, the following examples are used for detailed description. The experimental raw materials used in the following preparation examples of the application are all general commercially available products.

[0075] Preparation Example 1

[0076] The preparation method of the voltage-resistant monomer shown as formula M1 provided by the present preparation example is as follows:

[0077] First, 500 mL of anhydrous ethanol is subjected to ultrasonic reduction under pressure to remove oxygen dissolved in the anhydrous ethanol; 2 g of potassium hydroxide is added to the anhydrous ethanol and dissolved at room temperature; after the potassium hydroxide is completely dissolved, 5 g of p-methylphenol is added in 5 times; after complete dissolution, 6 g of 6-bromo-1-hexene is added, heated to micro-boiling, connected to a reflux device, and the reaction time is 7 h, and the experiment is carried out under N2 atmosphere.

[0078] Preparation Example 2

[0079] The preparation method of the voltage-resistant monomer shown as formula M2 provided by the present preparation example is as follows:

[0080] First, 500 mL of anhydrous ethanol is subjected to ultrasonic reduction under pressure to remove oxygen dissolved in the anhydrous ethanol; 2 g of potassium hydroxide is added to the anhydrous ethanol and dissolved at room temperature; after the potassium hydroxide is completely dissolved, 5 g of p-methylphenol is added in 5 times; after complete dissolution, 6 g of 6-bromo-1-hexene is added, heated to micro-boiling, connected to a reflux device, and the reaction time is 7 h, and the experiment is carried out under N2 atmosphere.

[0081] Preparation Example 3

[0082] The preparation method of the voltage-resistant monomer shown as formula M3 provided by the present preparation example is as follows:

[0083] First, 500 mL of anhydrous ethanol is subjected to ultrasonic reduction pressure to remove oxygen dissolved in the anhydrous ethanol; 4 g of potassium hydroxide is dissolved in the anhydrous ethanol at room temperature; after the potassium hydroxide is completely dissolved, 5 g of hydroquinone is added in 8 portions; after complete dissolution, 12 g of 6-bromo-1-hexene is added, heated to micro-boiling, connected to a reflux device, and the reaction time is 10 h, and the experiment is carried out under N2 atmosphere.

[0084] Preparation Example 4

[0085] The present preparation example provides a voltage-resistant monomer represented by formula M4, and the preparation method is as follows:

[0086] First, 500 mL of anhydrous DMF is subjected to ultrasonic reduction pressure to remove oxygen dissolved in the anhydrous DMF; 4 g of potassium hydroxide is dissolved in the anhydrous DMF at room temperature; after the potassium hydroxide is completely dissolved, 5 g of α-naphthol is added in 10 portions; after complete dissolution, 6 g of 6-bromo-1-hexene is added, heated to 80°C, connected to a reflux device, and the reaction time is 10 h, and the experiment is carried out under N2 atmosphere.

[0087] Preparation Example 5

[0088] The present preparation example provides a compound represented by formula M5, and the preparation method is as follows:

[0089] First, 500 mL of THF is subjected to ultrasonic reduction pressure to remove oxygen dissolved in the THF; 4 g of potassium hydroxide is dissolved in the THF at room temperature; after the potassium hydroxide is completely dissolved, 5 g of 4,4'-dihydroxybiphenyl is added in 10 portions; after complete dissolution, 12 g of 6-bromo-1-hexene is added, heated to micro-boiling, connected to a reflux device, and the reaction time is 10 h, and the experiment is carried out under N2 atmosphere.

[0090] Preparation Example 6

[0091] The present preparation example provides a voltage-resistant monomer represented by formula M6, and the preparation method is as follows:

[0092] First, 500 mL of THF is subjected to ultrasonic reduction pressure to remove oxygen dissolved in the THF; 4 g of potassium hydroxide is dissolved in the THF at room temperature; after the potassium hydroxide is completely dissolved, 5 g of 4,4'-dihydroxybiphenyl is added in 10 portions; after complete dissolution, 12 g of 6-bromo-1-hexene is added, heated to micro-boiling, connected to a reflux device, and the reaction time is 10 h, and the experiment is carried out under N2 atmosphere.

[0093] Preparation Example 7

[0094] The present preparation example provides a voltage-resistant monomer represented by formula M7, and the preparation method is as follows:

[0095] Firstly, 500 mL THF was subjected to ultrasonic reduction pressure to remove oxygen dissolved in THF; 4 g of potassium hydroxide was dissolved in THF at room temperature; after the potassium hydroxide was completely dissolved, 5 g of 4, 4'-dihydroxybenzophenone was added in 10 times; after complete dissolution, 12 g of 6-bromo-1-hexene was added, heated to micro boiling, and returned to the reflux device, the reaction time was 10 h, and the experiment was carried out in N2 atmosphere.

[0096] Example 1

[0097] The present embodiment provides a low-density polyethylene resistant to direct current breakdown, and the preparation method is as follows:

[0098] Take LDPE 49.5 g, 0.5 g of voltage-resistant monomer represented by formula M1 obtained from Preparation Example 1, and stir uniformly in a small container. Set the torque rheometer speed to 60 rpm, melt blend graft at 170°C for 15 min, and obtain a low-density polyethylene resistant to direct current breakdown.

[0099] Put the low-density polyethylene resistant to direct current breakdown into a Soxhlet extractor, extract with THF and other solvents for 36 h, and then dry the sample to remove the ungrafted voltage-resistant monomer to interfere with subsequent experiments. Take a small amount of purified low-density polyethylene resistant to direct current breakdown and base material (i.e. original LDPE) for gel permeation chromatography characterization, and the mobile phase is 1, 2, 4-trichlorobenzene, the experimental temperature is 150°C, the flow rate is 1.0 mL / min, and the GPC data are shown in Table 1 (wherein, Additive amount represents the addition amount of voltage-resistant monomer, Mn represents the number average molecular weight, Mw represents the weight average molecular weight, and Mw / Mn represents the molecular weight distribution).

[0100] Table 1

[0101]

[0102] The direct current breakdown test method is as follows:

[0103] Firstly, put the original LDPE and low-density polyethylene resistant to direct current breakdown into a high-temperature resistant mold, and place it between two copper plates, then place it on a flat vulcanizing instrument for preheating for 5 min, and press in the process, the pressure gradually increases from 0 to 16 MPa, take out the mold and cool at room temperature, obtain a film with a thickness of about 100 μm, and naturally place it for more than 36 h to eliminate its stress.

[0104] The direct current breakdown strength of the original LDPE and low-density polyethylene resistant to direct current breakdown was measured in a silicone oil environment at room temperature using a GJW-50KV type direct current breakdown tester, and the direct current voltage was raised at a rate of 1KV / s. The experimental data of the breakdown strength was analyzed using a two-parameter Weibull distribution (i.e. Weibull distribution). The calculation formula for Weibull distribution evaluation is as follows:

[0105] P = 1 - exp[-(E / α) β ];

[0106] Wherein, P represents the cumulative breakdown probability, E represents the measured DC breakdown strength value, a represents the characteristic breakdown strength, i.e. the DC breakdown strength when the cumulative breakdown probability is 63.2%, and β represents the shape parameter, which is generated when the function is statistically fitted, reflecting the degree of data dispersion.

[0107] Each sample was tested 24 times, and 15 sets of effective breakdown voltage data were taken. After Weibull distribution fitting, the DC breakdown strength at a cumulative breakdown probability of 63.2% was taken as the DC breakdown strength of the sample, and the value was 362 (KV / mm), and the original LDPE was 298 (KV / mm).

[0108] Example 2

[0109] This example provides a low-density polyethylene resistant to DC breakdown, and the preparation method is as follows:

[0110] Take LDPE 49.6g, and the voltage-resistant monomer represented by formula M2 obtained in Preparation Example 2 0.4g, stir uniformly in a small container, set the torque rheometer speed at 120 rpm, melt blend graft at 180℃ for 15 min, and obtain the DC breakdown-resistant LDPE.

[0111] The gel permeation chromatography characterization method is referred to Example 1, and the test data are shown in Table 2 as follows:

[0112] Table 2

[0113]

[0114] The DC breakdown test method is referred to Example 1, and the DC breakdown strength of the DC breakdown-resistant LDPE is 350 (KV / mm), and the original LDPE is 298 (KV / mm).

[0115] Example 3

[0116] This example provides a low-density polyethylene resistant to DC breakdown, and the preparation method is as follows:

[0117] Take LDPE 49.5g, and the voltage-resistant monomer represented by formula M3 obtained in Preparation Example 3 0.5g, stir uniformly in a small container, set the torque rheometer speed at 60 rpm, melt blend graft at 200℃ for 15 min, and obtain the modified LDPE.

[0118] The gel permeation chromatography characterization method is referred to Example 1, and the test data are shown in Table 3 as follows:

[0119] Table 3

[0120]

[0121] The DC breakdown test method is as described in Reference Example 1. The DC breakdown strength of the DC breakdown resistant LDPE is 440 (KV / mm), and that of the original LDPE is 298 (KV / mm).

[0122] Example 4

[0123] This example provides a DC breakdown resistant low density polyethylene, which is prepared as follows:

[0124] LDPE 49.5 g, and the voltage resistant monomer represented by formula M4 obtained in Preparation Example 4 0.5 g were stirred uniformly in a small container. The speed of the torque rheometer was set to 110 rpm, and the temperature was set to 190°C. The mixture was melt blended and grafted for 15 min to obtain the modified LDPE.

[0125] The gel permeation chromatography characterization method is as described in Reference Example 1. The test data are shown in Table 4 below.

[0126] Table 4

[0127]

[0128] The DC breakdown test method is as described in Reference Example 1. The DC breakdown strength of the DC breakdown resistant LDPE is 343 (KV / mm), and that of the original LDPE is 298 (KV / mm).

[0129] Example 5

[0130] LDPE 49.7 g, and the voltage resistant monomer represented by formula M5 obtained in Preparation Example 5 0.3 g were stirred uniformly in a small container. The speed of the torque rheometer was set to 100 rpm, and the temperature was set to 170°C. The mixture was melt blended and grafted for 15 min to obtain the DC breakdown resistant LDPE.

[0131] The gel permeation chromatography characterization method is as described in Reference Example 1. The test data are shown in Table 5 below.

[0132] Table 5

[0133]

[0134] The DC breakdown test method is as described in Reference Example 1. The DC breakdown strength of the DC breakdown resistant LDPE is 357 (KV / mm), and that of the original LDPE is 298 (KV / mm).

[0135] Example 6

[0136] LDPE 49.7 g, and the voltage resistant monomer represented by formula M6 obtained in Preparation Example 6 0.3 g were stirred uniformly in a small container. The speed of the torque rheometer was set to 90 rpm, and the temperature was set to 200°C. The mixture was melt blended and grafted for 9 min to obtain the DC breakdown resistant LDPE.

[0137] Gel permeation chromatography characterization method is referenced to example 1, and the test data is shown in table 6 below:

[0138] Table 6

[0139]

[0140] DC breakdown test method is referenced to example 1, and the DC breakdown strength of the DC breakdown resistant LDPE is 370 (KV / mm), and that of the original LDPE is 298 (KV / mm).

[0141] Example 7

[0142] Take 49.5g of LDPE and 0.5g of the voltage resistant monomer represented by formula M6 obtained in preparation example 7, stir them uniformly in a small container, set the speed of the torque rheometer at 120rpm, melt blend and graft at 180℃ for 9min, and obtain the DC breakdown resistant LDPE.

[0143] Gel permeation chromatography characterization method is referenced to example 1, and the test data is shown in table 7 below:

[0144] Table 7

[0145]

[0146] DC breakdown test method is referenced to example 1, and the DC breakdown strength of the DC breakdown resistant LDPE is 365 (KV / mm), and that of the original LDPE is 298 (KV / mm).

[0147] Comparative example 1

[0148] Take 49.5g of LDPE and 0.5g of 4-vinylphenylboronic acid, stir them uniformly in a small container, set the speed of the torque rheometer at 120rpm, melt blend and graft at 190℃ for 11min, and obtain the modified LDPE.

[0149] Gel permeation chromatography characterization method is referenced to example 1, and the test data is shown in table 8 below:

[0150] Table 8

[0151]

[0152] DC breakdown test method is referenced to example 1, and the DC breakdown strength of the modified LDPE is 210 (KV / mm), and that of the original LDPE is 307 (KV / mm).

[0153] The foregoing description of the disclosed embodiments enables one of ordinary skill in the art to make or use the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A voltage-resistant single body, characterized by, having a structural formula as shown in Formula I or Formula II: wherein R1 is selected from C2-C8 alkenyl with a double bond at the end; R2 is selected from hydrogen, C1-C6 alkyl, oxygen-containing group, or R2 and the carbon on which it is located and the adjacent carbon atom form an aromatic ring; R3 is selected from null, -O-, or -CO-; n = 1 or 2.

2. The voltage-resistant single body according to claim 1, characterized in that, R1 is selected from C2-C6 alkenyl with a double bond at the end; R2 is selected from hydrogen, C1-C4 alkyl, hydroxyl, aldehyde group, or R2 and the carbon on which it is located and the adjacent carbon atom form a benzene ring; when n = 2, the two -OR1 are located at the ortho position or the para position of the benzene ring.

3. The voltage-resistant single body according to claim 1 or 2, characterized in that, The voltage-resistant monomer is selected from any one of the following Formula M1-M7:

4. The method for producing a voltage-resistant single cell according to any one of claims 1 to 3, characterized by, comprising the following steps: etherification of a phenolic compound shown in Formula A and a halogenated hydrocarbon compound R1X in the presence of a basic substance to obtain a voltage-resistant monomer shown in Formula I; or etherification of a phenolic compound shown in Formula B and a halogenated hydrocarbon compound R1X in the presence of a basic substance to obtain a voltage-resistant monomer shown in Formula II; X in R1X is a halogen atom; 5. The preparation method according to claim 4, characterized in that, The etherification reaction is carried out in an inert atmosphere; The basic substance includes sodium hydroxide and / or potassium hydroxide.

6. The production method according to claim 5, wherein The phenolic compound shown in Formula A is dissolved in a solution of the basic substance in batches, after complete dissolution, the halogenated hydrocarbon compound R1X is added to undergo etherification reaction; The solution of the basic substance is obtained by dissolving the basic substance in a solvent, and the solvent includes any one or more of anhydrous ethanol, anhydrous DMF, anhydrous acetonitrile, or THF; R1X is selected from any one or more of 7-bromo-1-heptene, 6-bromo-1-hexene, 5-iodo-1-pentene, 4-bromo-1-butene, or 3-chloro-1-propene; The temperature of the etherification reaction is 50-120°C, and the time is 7-10h.

7. A low density polyethylene resistant to DC breakdown, characterized in that, The raw materials include: low-density polyethylene 99.0-99.8wt%, voltage-resistant monomer 0.2-1.0wt%; The voltage-resistant monomer is the voltage-resistant monomer according to any one of claims 1-3 or prepared according to the preparation method of any one of claims 4-6.

8. The low density polyethylene of claim 7, wherein, M of the low-density polyethylene resistant to direct current breakdown w 10.70 x 10 4 11.19 x 10 4 .

9. A process for the production of the low-density polyethylene resistant to DC breakdown according to claim 7 or 8, characterized in that, comprising the following steps: melt blending of the low-density polyethylene and the voltage-resistant monomer at 150-200°C to obtain a direct-current breakdown-resistant low-density polyethylene.

10. The method of claim 9, wherein, The time of the melt blending is 8-15min; The melt blending is carried out in a torque rheometer, and the rotation speed of the torque rheometer is 60-120rpm.

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