Voltage stabilizer, crosslinked polyethylene cable insulation material and preparation method thereof

Abstract

The invention provides a voltage stabilizer, a crosslinked polyethylene cable insulating material and a preparation method thereof, and relates to the technical field of cable insulating materials. The 5-oleoyloxy p-naphthoquinone is used as a voltage stabilizer of the crosslinked polyethylene cable insulating material, so that the energy of high-energy electrons can be consumed more quickly and efficiently; the electrical resistance of the cross-linked polyethylene insulating material is improved, and the problems that a voltage stabilizer added in an existing cross-linked polyethylene insulating material is prone to migration loss in the cable production, storage and use processes, and the action effect of the voltage stabilizer is reduced are solved.

Description

Technical Field

[0001] The invention relates to the technical field of cable insulation materials, and in particular to a voltage stabilizer, a cross-linked polyethylene cable insulation material and a preparation method thereof. Background Art

[0002] In the field of power transmission and communication, cable insulation materials are an important component of cables, which directly affects the safety, reliability and service life of cables. With the continuous development of power systems and the increasing popularity of communication networks, the requirements for the electrical resistance of cable insulation materials are becoming higher and higher. Improving the electrical strength of cross-linked polyethylene insulation materials is a crucial technical challenge. At present, 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 the electrical strength, the purification process of cable materials and cable manufacturing has made great progress, and the electrical strength of cross-linked polyethylene has certain limits. Therefore, it is difficult to further improve the working voltage level and operating stability of the cable insulation layer by relying on the improvement of purity. In order to achieve a greater improvement in the electrical resistance of cross-linked polyethylene insulation materials, it is necessary to rely on material modification technology.

[0003] Adding voltage stabilizers to cross-linked polyethylene insulation is an effective and easy-to-implement method to improve its electrical resistance. However, current voltage stabilizers have poor compatibility with polymers, which causes the tiny molecules of the voltage stabilizer to easily migrate and precipitate from the macromolecules of the polymer. This situation will eventually lead to the loss of the modification function of the voltage stabilizer, and may even cause the service life and electrical resistance of the cable insulation layer to be significantly weakened after the voltage stabilizer migrates and precipitates. In addition, the conjugated structure of most current voltage stabilizer molecules is small and has limited absorption capacity for high-energy electrons. The current grafted voltage stabilizers have limited absorption effect on high-energy electrons. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a voltage stabilizer, a cross-linked polyethylene cable insulation material containing the voltage stabilizer and a preparation method thereof, which improves the electrical resistance of the cross-linked polyethylene insulation material and solves the problem that the voltage stabilizer added to the existing cross-linked polyethylene insulation material is easily lost during the production, storage and use of the cable, thereby reducing the effect of the voltage stabilizer.

[0005] One of the objectives of the present invention is to provide a voltage stabilizer.

[0006] A second object of the present invention is to provide a method for preparing the voltage stabilizer.

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

[0008] A fourth object of the present invention is to provide a method for preparing the cross-linked polyethylene cable insulation material.

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

[0010] In a first aspect, the present invention provides a voltage stabilizer as shown in Formula 1,

[0011]

[0012] In a second aspect, the present invention provides a method for preparing the voltage stabilizer, comprising the following steps:

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

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

[0015] 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.

[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, preferably 4-dimethylaminopyridine (DMAP);

[0018] In some embodiments, the reaction temperature of step (2) is room temperature, and the reaction time is 2 to 7 hours, preferably 3 to 4 hours;

[0019] In some embodiments, in step (2), 1 M hydrochloric acid solution is added to quench the reaction; the mixture is extracted with ethyl acetate and dried with anhydrous sodium sulfate, and the solvent is spin-dried; and the crude product is purified by column chromatography, with the eluent being petroleum ether / ethyl acetate.

[0020] The reaction route is as follows:

[0021]

[0022] The invention adopts 5-hydroxyl-p-naphthoquinone and oleoyl chloride to react to obtain 5-oleoyloxy-p-naphthoquinone grafted voltage stabilizer, which has a naphthalene ring, two carbonyl groups and an ester group and has a significant electron-withdrawing effect.

[0023] In a third aspect, the present invention provides a cross-linked polyethylene cable insulation material, which is prepared from raw materials comprising the following parts by mass: 100 parts of low-density polyethylene, 1.6 to 2.0 parts of dicumyl peroxide, 0.2 to 0.5 parts of an antioxidant and 0.3 to 1.0 parts of the voltage stabilizer.

[0024] It should be noted that phr can also be used to express.

[0025] The source of low-density polyethylene is not particularly limited, and it can be obtained from the market or prepared by methods known in the art. Preferably, 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 .

[0026] The added amount of low-density polyethylene was 100 parts.

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

[0028] The antioxidant may 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), β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (Antioxidant 1076), 4,4'-thiobis(6-tert-butyl-m-cresol) (Antioxidant 300), etc., preferably 4,4'-thiobis(6-tert-butyl-m-cresol).

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

[0030] The added amount of the voltage stabilizer of the present invention is, for example, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.0 part.

[0031] In a fourth aspect, the present invention provides a method for preparing a cross-linked polyethylene cable insulation material, comprising the following steps:

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

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

[0034] (c) crosslinking 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 to 120° C.;

[0036] In some embodiments, in step (c), the temperature for crosslinking and grafting is 140-280° C., and the pressure is 15-20 MPa.

[0037] Beneficial effects:

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

[0039] The present invention has been described in detail above, but the above embodiments are only illustrative in nature and are not intended to limit the present invention. In addition, this article is not limited by any theory described in the above prior art or invention content or the following examples. DETAILED DESCRIPTION

[0040] The present invention is further described below in conjunction with examples. It should be noted that the following examples are provided for illustrative purposes only and do not constitute a limitation on the scope of protection claimed for the present invention.

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

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

[0043] 5-Hydroxy-p-naphthoquinone was purchased from Aladdin Biochemical Technology Co., Ltd.

[0044] The low-density polyethylene was obtained from Sinopec Qilu Petrochemical Plastics Plant, with a melt index of 2.0 g / 10 min (190 °C, 2.16 kg) and a density of 0.920 g / cm 3 .

[0045] Preparation Example 1 Preparation of voltage stabilizer

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

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

[0048] (2) Under a nitrogen atmosphere, the mixture obtained in (1) was mixed with 19 mL of oleoyl chloride and 53 mg of DMAP and stirred at room temperature for 3 h for reaction. After the reaction was completed, a 1 M hydrochloric acid solution was added to quench the reaction. The obtained mixture was extracted with ethyl acetate and dried over anhydrous sodium sulfate. The solvent was spin-dried and finally the crude product was purified by column chromatography using petroleum ether / ethyl acetate as an eluent to obtain a 5-oleoyloxy naphthoquinone voltage stabilizer; wherein the molar ratio of 5-hydroxy naphthoquinone to oleoyl chloride, DMAP, and pyridine was 1:2:0.015:40.

[0049] Example 1

[0050] A 5-oleoyloxy naphthoquinone voltage stabilizer modified cross-linked polyethylene cable insulation material comprises the following raw materials in parts by mass: 100 parts of low-density polyethylene, 1.8 parts of diisopropylbenzene peroxide, 0.2 parts of antioxidant 300, and 0.4 parts of the voltage stabilizer of Preparation Example 1.

[0051] This embodiment provides a method for preparing a cross-linked polyethylene cable insulation material, comprising the following steps:

[0052] (1) low-density polyethylene, antioxidant 300, and voltage stabilizer are mixed and kneaded uniformly at 115° C.;

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

[0054] (3) The blended pellets obtained in step (2) are cross-linked and grafted at 160° C. and a pressure of 15 MPa for 40 minutes to obtain a voltage stabilizer grafted cross-linked polyethylene cable insulation material.

[0055] Example 2

[0056] A 5-oleoyloxy naphthoquinone voltage stabilizer modified cross-linked polyethylene cable insulation material comprises the following raw materials in parts by mass: 100 parts of low-density polyethylene, 1.8 parts of diisopropylbenzene peroxide, 0.2 parts of antioxidant 300, and 0.6 parts of the voltage stabilizer of Preparation Example 1.

[0057] The preparation method of the cross-linked polyethylene cable insulation material is the same as that in Example 1.

[0058] Example 3

[0059] A 5-oleoyloxy naphthoquinone voltage stabilizer modified cross-linked polyethylene cable insulation material comprises the following raw materials in parts by mass: 100 parts of low-density polyethylene, 1.8 parts of diisopropylbenzene peroxide, 0.2 parts of antioxidant 300, and 0.8 parts of the voltage stabilizer of Preparation Example 1.

[0060] The preparation method of the cross-linked polyethylene cable insulation material is the same as that in Example 1.

[0061] Example 4

[0062] A 5-oleoyloxy naphthoquinone voltage stabilizer modified cross-linked polyethylene cable insulation material comprises the following raw materials in parts by mass: 100 parts of low-density polyethylene, 1.8 parts of diisopropylbenzene peroxide, 0.2 parts of antioxidant 300, and 1.0 parts of the voltage stabilizer of Preparation Example 1.

[0063] The preparation method of the cross-linked polyethylene cable insulation material is the same as that in Example 1.

[0064] Comparative Example 1

[0065] A cross-linked polyethylene cable insulation material comprises the following raw materials in parts by mass: 100 parts of low-density polyethylene, 1.8 parts of diisopropylbenzene peroxide, and 0.2 parts of antioxidant 300.

[0066] The preparation method of cross-linked polyethylene cable insulation material comprises the following steps:

[0067] (1) 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) The blended pellets obtained in step (2) are cross-linked at 160° C. and a pressure of 15 MPa for 40 min to obtain a cross-linked polyethylene cable insulation material.

[0070] Comparative Example 2

[0071] A voltage stabilizer modified cross-linked polyethylene cable insulation material comprises the following raw materials in parts by mass: 100 parts of low-density polyethylene, 1.8 parts of diisopropylbenzene peroxide, 0.2 parts of antioxidant 300, and 0.24 parts of 5-hydroxynaphthoquinone voltage stabilizer (0.6 parts of 5-oleoyloxynaphthoquinone voltage stabilizer contains 0.24 parts of 5-hydroxynaphthoquinone).

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

[0073] (1) low-density polyethylene, antioxidant 300, and 5-hydroxy-p-naphthoquinone voltage stabilizer are mixed and kneaded uniformly at 115° C.;

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

[0075] (3) Cross-linking the blended pellets obtained in step (2) at 160° C. 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 5-hydroxy-p-naphthoquinone in the voltage stabilizer of Preparation Example 1 is replaced with 5-hydroxy-1-naphthoic acid to prepare the voltage stabilizer, and the added amount is 0.26 parts.

[0078] Effect Example 1

[0079] The test results of the DC breakdown field strength of the cross-linked polyethylene cable insulation materials of Examples 1 to 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 to 4 and Comparative Examples 1 and 3 were made into circular samples with a diameter of 80 mm and a thickness of 100 μm. The diameter of the high-voltage electrode was 25 mm, and the diameter of the ground electrode was 50 mm. The samples and electrodes were immersed in silicone oil and tested at room temperature with a pressurization rate of 0.5 kV / s. The test data were statistically analyzed using Weibull distribution.

[0081] Table 1 DC breakdown field strength

[0082]

[0083] As shown in Table 1, the DC breakdown field strength of the cross-linked polyethylene cable insulation material increases with the increase of the amount of voltage stabilizer added. When 1.0 part of 5-oleoyloxy naphthoquinone voltage stabilizer is added, the DC breakdown field strength (488kV / mm) of the cross-linked polyethylene cable insulation material is increased by about 32% compared with the DC breakdown field strength (370kV / mm) of the cross-linked polyethylene cable insulation material without adding voltage stabilizer. 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 naphthoquinone, because the electron-withdrawing ability of the carboxyl group is weaker than that of the carbonyl group, and the delocalization ability of the conjugated electrons of the naphthalene ring is weaker. It can be seen that the addition of 5-oleoyloxy naphthoquinone voltage stabilizer can improve the DC insulation performance of the cross-linked polyethylene cable insulation material.

[0084] Effect Example 2

[0085] The current density values ​​of the cross-linked polyethylene cable insulation materials of Example 2 and Comparative Examples 1 to 2 were tested at an electric field strength of 20 kV / mm. The test results are shown in Table 2.

[0086] Test method: The cross-linked polyethylene cable insulation materials of Example 2 and Comparative Examples 1-2 are made into samples with a thickness of 200μm and a side length of 10cm×10cm, and the test field strength is 20kV / mm, the measuring pole diameter is 50mm, the inner diameter of the protective pole is 54mm, the outer diameter is 74mm, and the high-voltage pole diameter is 76mm. The sample and the electrode are placed in a shielding box, and the field strength is gradually increased by 5kV / mm. The quasi-steady-state current value after applying different voltages for 15 minutes 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 <![CDATA[Current density (A / m 2 )]]> <![CDATA[1.12×10 -7 ]]> <![CDATA[1.78×10 -7 ]]> <![CDATA[4.14×10 -6 ]]>

[0089] It can be seen from Table 2 that adding 0.6 parts of 5-oleoyloxy naphthoquinone voltage stabilizer can increase the current density of cross-linked polyethylene cable insulation material from 1.78×10 -7 A / m 2 Down to 1.12×10 -7 A / m 2 , which is an order of magnitude lower than the current density of the cross-linked polyethylene cable insulation material with 0.24 parts of 5-hydroxy naphthoquinone voltage stabilizer added. This shows that 5-oleoyloxy naphthoquinone voltage stabilizer can be evenly distributed in the material through the grafting reaction, inhibiting the field conductivity and reducing the serious negative impact of naphthoquinone voltage stabilizers on the conductivity of cross-linked polyethylene.

[0090] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents, without departing from the spirit and essence of the claims of the present invention; and these modifications or replacements are still within the scope defined by the claims of the present invention.

Claims

1. A voltage stabilizer of formula 1, 2. A method for preparing the voltage stabilizer according to claim 1, characterized in that: The following steps are involved: (1) dissolving 5-hydroxy-p-naphthoquinone in a solvent to obtain a mixed solution; (2) under a nitrogen atmosphere, mixing the mixed solution obtained in step (1) with oleoyl chloride and a catalyst to react, quenching the reaction after the reaction is completed, extracting, drying, and purifying the obtained crude product to obtain a voltage stabilizer; 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 preparation method according to claim 2, characterized in that: 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, preferably 4-dimethylaminopyridine (DMAP); The reaction temperature of step (2) is room temperature, and the reaction time is 2 to 7 hours, preferably 3 to 4 hours.

5. A cross-linked polyethylene cable insulation material, characterized in that: The invention is prepared from the following raw materials in parts by weight: 100 parts of low-density polyethylene, 1.6 to 2.0 parts of dicumyl peroxide, 0.2 to 0.5 parts of antioxidant and 0.3 to 1.0 parts of the voltage stabilizer according to claim 1.

6. The cross-linked polyethylene cable insulation material according to claim 5, characterized in that: 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 .

7. The cross-linked polyethylene cable insulation material according to claim 5, characterized in that: The antioxidant is one or more of N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and 4,4'-thiobis(6-tert-butyl-m-cresol), preferably 4,4'-thiobis(6-tert-butyl-m-cresol).

8. A method for preparing the cross-linked polyethylene cable insulation material according to any one of claims 5 to 7, characterized in that: The following steps are involved: (a) mixing low-density polyethylene, an antioxidant and the voltage stabilizer uniformly to obtain a mixture; (b) spraying dicumyl peroxide heated to a molten state into the mixed material 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 cross-linked polyethylene cable insulation material.

9. The preparation method according to claim 8, characterized in that: In step (a), the mixing temperature is 110-120°C.

10. The preparation method according to claim 8, characterized in that: In step (c), the temperature for crosslinking and grafting is 140-280° C., and the pressure is 15-20 MPa.

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