A voltage stabilizer, a crosslinked polyethylene cable insulation material, and a method for producing the same

Abstract

The application provides a voltage stabilizer, a crosslinked polyethylene cable insulation material and a preparation method thereof, and relates to the technical field of cable insulation materials. 5-oleoyloxy p-naphthoquinone is used as a voltage stabilizer of the crosslinked polyethylene cable insulation material, the energy of high-energy electrons can be consumed more quickly and more efficiently, the problem that voltage stabilizers added in the existing crosslinked polyethylene insulation material are prone to migration and loss during the production, storage and use of the cable and the problem that the effect of the voltage stabilizer is reduced can be solved while the electric performance of the crosslinked polyethylene insulation material is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cable insulation materials, and particularly relates to a voltage stabilizer, a cross-linked polyethylene cable insulation material and a preparation method thereof. BACKGROUND

[0002] In the field of power transmission and communication, cable insulation materials are an important component of cables, directly affecting the safety, reliability and service life of cables. With the continuous development of power systems and the increasing popularity of communication networks, the demand for the electrical properties of cable insulation materials is also increasing. Improving the electrical strength of cross-linked polyethylene insulation materials is a crucial technical challenge. Currently, improving the purity of the insulation layer and modifying the material are two common methods. Although the improvement of purity can reduce the adverse effects of impurities in the insulation layer on electrical strength, the purification process of cable materials and cable manufacturing has made great progress, and there is a certain limit to the electrical strength of cross-linked polyethylene. Therefore, it is difficult to further improve the working voltage level and operational stability of the cable insulation layer by relying on the improvement of purity. In order to achieve a greater improvement in the electrical properties of cross-linked polyethylene insulation materials, it is necessary to rely on material modification technology.

[0003] Adding a voltage stabilizer to cross-linked polyethylene insulation materials is an effective and easy-to-implement method that can improve their electrical properties. However, the current voltage stabilizers have poor compatibility with polymers, causing small molecules of voltage stabilizers to easily migrate and precipitate from the large molecules of polymers. This ultimately leads to the loss of modification function of the voltage stabilizer, and may even cause the service life and electrical properties of the cable insulation layer to be significantly weakened after the voltage stabilizer migrates and precipitates. In addition, most of the current voltage stabilizer molecules have small conjugated structures and limited absorption capacity for high-energy electrons. The current grafting type voltage stabilizer has limited absorption effect on high-energy electrons. SUMMARY

[0004] In view of the deficiencies in the prior art, the present application provides a voltage stabilizer, a cross-linked polyethylene cable insulation material containing the voltage stabilizer and a preparation method thereof, which improves the electrical properties of cross-linked polyethylene insulation materials while solving the problem of the voltage stabilizer added in the current cross-linked polyethylene insulation materials being easily migrated and wasted during the production, storage and use of cables, thereby reducing the effect of the voltage stabilizer.

[0005] One of the purposes of the present application is to provide a voltage stabilizer.

[0006] The second purpose of the present application is to provide a preparation method of the voltage stabilizer.

[0007] The third purpose of the present application is to provide a cross-linked polyethylene cable insulation material containing the voltage stabilizer.

[0008] The fourth object of the present application is to provide a preparation method of the crosslinked polyethylene cable insulation material.

[0009] In order to achieve the above-mentioned objects of the present application, the following technical solutions are adopted:

[0010] In a first aspect, the present application provides a voltage stabilizer shown in formula 1,

[0011]

[0012] In a second aspect, the present application provides a preparation method of the voltage stabilizer, comprising the following steps:

[0013] (1) dissolving 5-hydroxy p-naphthoquinone in a solvent to obtain a mixed solution;

[0014] (2) mixing the mixed solution obtained in step (1) with oleoyl chloride and a catalyst under a nitrogen atmosphere to perform a reaction, quenching the reaction after the reaction is completed, and extracting, drying and purifying the obtained crude product to obtain the voltage stabilizer;

[0015] The molar ratio of 5-hydroxy p-naphthoquinone, oleoyl chloride, the catalyst and the solvent is 1:1.5-3:0.01-0.02:30-50.

[0016] In some embodiments, the solvent in step (1) is any one of dichloromethane, chloroform, dichloroethane, trichloroethane, pyridine and tetrahydrofuran;

[0017] In some embodiments, the catalyst in step (2) is one or more of triethylamine, 4-dimethylaminopyridine (DMAP), 1,8-diazabicyclo[5.4.0]-7-undecane (DBU), piperidine and N,N-diisopropylethylamine, and preferably 4-dimethylaminopyridine (DMAP);

[0018] In some embodiments, the reaction temperature in step (2) is room temperature, and the reaction time is 2-7h, and preferably 3-4h;

[0019] In some embodiments, 1M hydrochloric acid solution is added to quench the reaction in step (2); ethyl acetate is used for extraction, and anhydrous sodium sulfate is used for drying, and the solvent is rotary evaporated; column chromatography is used for purifying the crude product, and petroleum ether / ethyl acetate is used as the eluent.

[0020] The reaction route is as follows:

[0021]

[0022] The 5-hydroxy p-naphthoquinone and the oleoyl chloride are reacted to obtain the 5-oleoyloxy p-naphthoquinone grafted voltage stabilizer, and the structure has a naphthalene ring, two carbonyl groups and an ester group, and the electron-withdrawing effect is significant.

[0023] In a third aspect, the present application provides a cross-linked polyethylene cable insulation material, which is prepared from raw materials including low density polyethylene 100 parts, dicumyl peroxide 1.6-2.0 parts, antioxidant 0.2-0.5 parts and the voltage stabilizer 0.3-1.0 parts.

[0024] It should be noted that the parts can also be expressed in phr.

[0025] The low density polyethylene is not particularly limited in source, and can be commercially available or prepared by known methods in the art. Preferably, the low density polyethylene has a melt index of 1.8-2.1 g / 10 min and a density of 0.91-0.93 g / cm 3 .

[0026] The low density polyethylene is added in an amount of 100 parts.

[0027] The dicumyl peroxide is added in an amount of, for example, 1.6, 1.7, 1.8, 1.9, 2.0 parts.

[0028] The antioxidant can be an antioxidant known in the art, including but not limited to N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine (antioxidant 1098), pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (antioxidant 1010), n-octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant 1076), 4,4'-thiobis(6-tert-butyl-m-cresol) (antioxidant 300), etc., and is preferably 4,4'-thiobis(6-tert-butyl-m-cresol).

[0029] The antioxidant is added in an amount of, for example, 0.2, 0.3, 0.4, 0.5 parts.

[0030] The voltage stabilizer is added in an amount of, for example, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0 parts.

[0031] In a fourth aspect, the present application provides a preparation method of a cross-linked polyethylene cable insulation material, which includes the following steps:

[0032] (a) uniformly mixing low density polyethylene, an antioxidant and the voltage stabilizer to obtain a mixture;

[0033] (b) spraying the dicumyl peroxide heated to a molten state into the mixture obtained in step (a), and then cooling and granulating to obtain a blended granule;

[0034] (c) cross-linking and grafting the blended granules obtained in step (b) to obtain a cross-linked polyethylene cable insulation material.

[0035] In some embodiments, in step (a), the mixing temperature is 110-120℃;

[0036] In some embodiments, in step (c), the cross-linking and grafting temperature is 140-280℃, and the pressure is 15-20 MPa.

[0037] Advantages:

[0038] The present application provides a 5-oleoyloxy p-naphthoquinone grafted voltage stabilizer, which is used as a voltage stabilizer for cross-linked polyethylene cable insulation material. First, in the cross-linking process of low-density polyethylene, the unsaturated double bond in the 5-oleoyloxy p-naphthoquinone grafted voltage stabilizer can be grafted onto the polyethylene molecular chain through a free radical addition reaction, fundamentally improving the problem that small-molecule voltage stabilizers are easily migrated out when added to the polymer in a traditional blending manner, and ensuring the long-term effect of the voltage stabilizer. Second, the 5-oleoyloxy p-naphthoquinone grafted voltage stabilizer contains two parallel six-membered rings, which greatly increases the electron cloud action space range. In addition, the ester group and the carbonyl group have an electron-withdrawing effect, further enhancing the delocalization of π electrons on the naphthoquinone ring, and then more quickly and efficiently consuming the energy of high-energy electrons, avoiding the impact and damage of high-energy electrons on the polyethylene molecular chain, thereby inhibiting the initiation of electrical treeing and improving the DC breakdown strength of cross-linked polyethylene. Third, the stabilizer used in the present application is introduced into the polyethylene molecular chain through a grafting reaction of double bonds, so it has good uniformity, which allows it to form a uniform and dense electron action space in the polyethylene molecular chain, thereby reducing the serious negative impact of the voltage stabilizer on the electrical conductivity of cross-linked polyethylene.

[0039] The present application has been described in detail above, but the above embodiments are merely illustrative in nature and are not intended to limit the present application. Furthermore, the present text is not limited by any theory described in the foregoing prior art or summary of the invention or in the following examples. DETAILED DESCRIPTION

[0040] The present application is further illustrated below with reference to examples, and it should be noted that the following examples are provided only for illustrative purposes and do not constitute a limitation on the scope of the present application.

[0041] Unless otherwise specified, the raw materials, reagents, and methods used in the examples are conventional raw materials, reagents, and methods in the art.

[0042] The raw materials involved in the examples and comparative examples are as follows:

[0043] 5-hydroxy-p-naphthoquinone was purchased from Aldrich.

[0044] Low density polyethylene was from Qilu Petrochemical Plastic Factory, SINOPEC, with melt index of 2.0 g / 10 min (190℃, 2.16 kg) and density of 0.920 g / cm 3 .

[0045] Preparation of the voltage stabilizer of Preparation Example 1

[0046] A method for preparing a 5-oleoyloxy-p-naphthoquinone voltage stabilizer, comprising the following steps:

[0047] (1) dissolving 5 g of 5-hydroxy-p-naphthoquinone in 97 mL of pyridine to obtain a mixture;

[0048] (2) mixing the mixture obtained in (1) with 19 mL of oleoyl chloride and 53 mg of DMAP under a nitrogen atmosphere and stirring at room temperature for 3 h to perform a reaction, adding a 1M hydrochloric acid solution to quench the reaction after the reaction is completed, extracting the obtained mixture with ethyl acetate and drying with anhydrous sodium sulfate, spinning to dry the solvent, and finally purifying the crude product by column chromatography using petroleum ether / ethyl acetate as an eluent to obtain a 5-oleoyloxy-p-naphthoquinone voltage stabilizer; wherein the molar ratio of 5-hydroxy-p-naphthoquinone to oleoyl chloride, DMAP and pyridine is 1:2:0.015:40.

[0049] Example 1

[0050] A 5-oleoyloxy-p-naphthoquinone voltage stabilizer modified crosslinked polyethylene cable insulation material, comprising the following mass fractions of raw materials: 100 parts of low density polyethylene, 1.8 parts of dicumyl peroxide, 0.2 parts of antioxidant 300, and 0.4 parts of the voltage stabilizer of Preparation Example 1.

[0051] The present example provides a method for preparing a crosslinked polyethylene cable insulation material, comprising the following steps:

[0052] (1) uniformly mixing low density polyethylene, antioxidant 300 and voltage stabilizer at 115℃;

[0053] (2) spraying dicumyl peroxide heated to a molten state into the mixture obtained in (1), and then cooling and granulating to obtain a blended granule;

[0054] (3) crosslinking and grafting the blended granule obtained in step (2) at 160℃ and a pressure of 15 MPa for 40 min to obtain a voltage stabilizer grafted crosslinked polyethylene cable insulation material.

[0055] Example 2

[0056] A 5-oleoyloxy p-naphthoquinone voltage stabilizer modified crosslinked polyethylene cable insulating material, comprising the following raw materials in mass parts: 100 parts of low density polyethylene, 1.8 parts of dicumyl peroxide, 0.2 parts of antioxidant 300, 0.6 parts of the voltage stabilizer of Preparation Example 1.

[0057] The preparation method of the crosslinked polyethylene cable insulating material is the same as that of Example 1.

[0058] Example 3

[0059] A 5-oleoyloxy p-naphthoquinone voltage stabilizer modified crosslinked polyethylene cable insulating material, comprising the following raw materials in mass parts: 100 parts of low density polyethylene, 1.8 parts of dicumyl peroxide, 0.2 parts of antioxidant 300, 0.8 parts of the voltage stabilizer of Preparation Example 1.

[0060] The preparation method of the crosslinked polyethylene cable insulating material is the same as that of Example 1.

[0061] Example 4

[0062] A 5-oleoyloxy p-naphthoquinone voltage stabilizer modified crosslinked polyethylene cable insulating material, comprising the following raw materials in mass parts: 100 parts of low density polyethylene, 1.8 parts of dicumyl peroxide, 0.2 parts of antioxidant 300, 1.0 parts of the voltage stabilizer of Preparation Example 1.

[0063] The preparation method of the crosslinked polyethylene cable insulating material is the same as that of Example 1.

[0064] Comparative Example 1

[0065] A crosslinked polyethylene cable insulating material, comprising the following raw materials in mass parts: 100 parts of low density polyethylene, 1.8 parts of dicumyl peroxide, 0.2 parts of antioxidant 300.

[0066] The preparation method of the crosslinked polyethylene cable insulating material comprises the following steps:

[0067] (1) uniformly mixing low density polyethylene and antioxidant 300 at 115°C;

[0068] (2) spraying dicumyl peroxide heated to a molten state into the mixture obtained in (1), and then cooling and granulating to obtain blended granules;

[0069] (3) crosslinking the blended granules obtained in step (2) at 160°C and a pressure of 15 MPa for 40 min to obtain a crosslinked polyethylene cable insulating material.

[0070] Comparative Example 2

[0071] A voltage stabilizer modified cross-linked polyethylene cable insulation material, comprising the following raw materials in mass fraction: 100 parts of low density polyethylene, 1.8 parts of dicumyl peroxide, 0.2 parts of antioxidant 300, 0.24 parts of 5-hydroxy-p-naphthoquinone voltage stabilizer (0.6 parts of 5-octanoyloxy-p-naphthoquinone voltage stabilizer contains 0.24 parts of 5-hydroxy-p-naphthoquinone).

[0072] A preparation method of the cross-linked polyethylene cable insulation material comprises the following steps:

[0073] (1) uniformly mixing low density polyethylene, antioxidant 300 and 5-hydroxy-p-naphthoquinone voltage stabilizer at 115℃;

[0074] (2) spraying dicumyl peroxide heated to a molten state into the mixture obtained in (1), then cooling and granulating to obtain blended granules;

[0075] (3) cross-linking the blended granules obtained in step (2) at 160℃ and a pressure of 15 MPa for 40 min to obtain a voltage stabilizer grafted cross-linked polyethylene cable insulation material.

[0076] Comparative Example 3

[0077] The difference between this comparative example and Example 2 is that the voltage stabilizer of Preparation Example 1 is replaced by a voltage stabilizer prepared by using 5-hydroxy-1-naphthoic acid instead of 5-hydroxy-p-naphthoquinone, and the amount added is 0.26 parts.

[0078] Example 1

[0079] The DC breakdown field strengths of the cross-linked polyethylene cable insulation materials of Examples 1-4 and Comparative Examples 1 and 3 are shown in Table 1.

[0080] Test method: the cross-linked polyethylene cable insulation materials of Examples 1-4 and Comparative Examples 1 and 3 are made into circular samples with a diameter of 80 mm and a thickness of 100 μm, the high voltage electrode has a diameter of 25 mm, the ground electrode has a diameter of 50 mm, the sample and the electrodes are both immersed in silicone oil, the test is carried out at room temperature, the pressure rate is 0.5 kV / s, and the test data is statistically analyzed using Weibull distribution.

[0081] Table 1 DC breakdown field strength

[0082]

[0083] From Table 1, it can be seen that the DC breakdown field strength of the crosslinked polyethylene cable insulation material increases with the increase of the amount of the voltage stabilizer. When 5-oleoyloxy-p-naphthoquinone voltage stabilizer is added in an amount of 1.0 parts, the DC breakdown field strength of the crosslinked polyethylene cable insulation material (488 kV / mm) is increased by about 32% compared with the DC breakdown field strength of the crosslinked polyethylene cable insulation material without the voltage stabilizer (370 kV / mm). In Comparative Example 3, the addition of 5-hydroxy-1-naphthoic acid also improves the DC breakdown field strength of the material, but the effect is not as good as that of 5-oleoyloxy-p-naphthoquinone, because the electron-withdrawing ability of the carboxyl group is weaker than that of the carbonyl group, and the electron-withdrawing ability of the naphthalene ring is weaker. It can be seen that the addition of 5-oleoyloxy-p-naphthoquinone voltage stabilizer can improve the DC insulation performance of the crosslinked polyethylene cable insulation material.

[0084] Example 2

[0085] The current density values of the crosslinked polyethylene cable insulation materials of Test Example 2 and Comparative Examples 1-2 at an electric field strength of 20 kV / mm are shown in Table 2.

[0086] Test method: The crosslinked polyethylene cable insulation materials of Example 2 and Comparative Examples 1-2 are made into samples with a thickness of 200 μm and a side length of 10 cm x 10 cm, the test field strength is 20 kV / mm, the measurement electrode diameter is 50 mm, the inner diameter of the guard electrode is 54 mm, the outer diameter is 74 mm, and the high-voltage electrode diameter is 76 mm. The sample and the electrode are placed in a shielding box, and the field strength is gradually increased by steps of 5 kV / mm. The quasi-steady-state current value after applying different voltages for 15 min can be read by a picoammeter, which is the current density value.

[0087] Table 2 Current density

[0088] Performance Example 2 Comparative Example 1 Comparative Example 2 Current density (A / m 2 ) 1.12 x 10 -7 ]] 1.78 x 10 -7 ]] 4.14 x 10 -6 ]]

[0089] As can be seen from Table 2, the addition of 0.6 parts of 5-oleoyloxy-p-naphthoquinone voltage stabilizer can reduce the current density value of the crosslinked polyethylene cable insulation material from 1.78 x 10 -7 A / m 2 to 1.12 x 10 -7 A / m 2 , which is an order of magnitude lower than the current density value of the crosslinked polyethylene cable insulation material with 0.24 parts of 5-hydroxy-p-naphthoquinone voltage stabilizer. It shows that 5-oleoyloxy-p-naphthoquinone voltage stabilizer can be uniformly distributed in the material through grafting reaction, inhibit the field-induced conductivity, and reduce the serious negative impact of p-naphthoquinone voltage stabilizer on the conductivity of crosslinked polyethylene.

[0090] The above embodiments are only used to illustrate the technical solutions of the present application, but not limit the present application. Although the present application is described in detail with reference to the above embodiments, it should be understood by those skilled in the art that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced equivalently without departing from the spirit and essence of the present application defined in the claims of the present application.

Claims

1. A voltage stabilizer of formula 1, Formula 1.

2. A process for the preparation of the voltage stabilizer as claimed in claim 1, wherein, comprising the following steps: (1) dissolving 5-hydroxy-p-naphthoquinone in a solvent to obtain a mixture; (2) mixing the mixture obtained in step (1) with oleoyl chloride and a catalyst under a nitrogen atmosphere to perform a reaction, quenching the reaction after the reaction is completed, and obtaining the voltage stabilizer after extraction, drying and purification of the obtained crude product; wherein the molar ratio of 5-hydroxy-p-naphthoquinone to oleoyl chloride, catalyst and solvent is 1:1.5-3:0.01-0.02:30-50.

3. The preparation method according to claim 2, characterized in that, The solvent in step (1) is any one of dichloromethane, chloroform, dichloroethane, trichloroethane, pyridine and tetrahydrofuran.

4. The production method according to claim 2, characterized by, The catalyst in step (2) is one or more of triethylamine, 4-dimethylaminopyridine, 1,8-diazabicyclo[5.4.0]-7-undecane, piperidine and N,N-diisopropylethylamine; The reaction temperature in step (2) is normal temperature, and the reaction time is 2-7 h.

5. The preparation method according to claim 4, characterized in that, The catalyst in step (2) is 4-dimethylaminopyridine; The reaction time in step (2) is 3-4 h.

6. A crosslinked polyethylene cable insulation material characterized in that, It is prepared from raw materials including low-density polyethylene 100 parts, dicumyl peroxide 1.6-2.0 parts, an antioxidant 0.2-0.5 parts and the voltage stabilizer of claim 1 0.3-1.0 parts.

7. The crosslinked polyethylene cable insulation material of claim 6, wherein, The low density polyethylene has a melt index of 1.8 to 2.1 g / 10 min and a density of 0.91 to 0.93 g / cm 3 .

8. The crosslinked polyethylene cable insulation material of claim 6, wherein, The antioxidant is one or more of N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine, tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]pentaerythritol ester, β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid n-octadecyl ester and 4,4'-thiobis(6-tert-butyl-m-cresol).

9. The crosslinked polyethylene cable insulation material of claim 8, wherein, The antioxidant is 4,4'-thiobis(6-tert-butyl-m-cresol).

10. A process for the preparation of a crosslinked polyethylene cable insulation material as claimed in any one of claims 6 to 9, characterized in that, comprising the following steps: (a) uniformly mixing low-density polyethylene, an antioxidant and the voltage stabilizer to obtain a mixture; (b) spraying dicumyl peroxide heated to a molten state into the mixture obtained in step (a), and then cooling and granulating to obtain blended granules; (c) crosslinking and grafting the blended granules obtained in step (b) to obtain a crosslinked polyethylene cable insulation material.

11. The method of claim 10, wherein, In step (a), the mixing temperature is 110-120°C.

12. The method of claim 10, wherein, In step (c), the crosslinking and grafting temperature is 140-280°C, and the pressure is 15-20 MPa.

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