Application of 3-cinnamoyl-4-hydroxycoumarin, cable insulation material and preparation method of cable insulation material

Abstract

The invention provides application of 3-cinnamoyl-4-hydroxycoumarin, a cable insulation material and a preparation method of the cable insulation material, and relates to the technical field of cable insulation materials. 3-cinnamoyl-4-hydroxycoumarin is used as a voltage stabilizer to prepare the cable insulation material, so that the electrical resistance of the cable insulation material is improved, and the problems that the voltage stabilizer added in the existing cable insulation material is easy to migrate and lose in the production, storage and use processes of cables and the action effect of the voltage stabilizer is reduced are solved; and meanwhile, the problem of photodegradation caused under the action of a high-voltage electric field is solved.

Description

Technical Field

[0001] The invention relates to the technical field of cable insulation materials, and in particular to application of 3-cinnamoyl-4-hydroxycoumarin as a voltage stabilizer in the preparation of cable insulation materials, the cable insulation material and a preparation method thereof. Background Art

[0002] Building a new power system with new energy as the main body will accelerate the upgrade of the power grid to the energy Internet, which puts higher requirements on the electrical resistance of cross-linked polyethylene (XLPE) cable materials. At present, improving the purity of the XLPE insulation layer and modifying the material are two common methods. The purification process of cable materials and cable manufacturing has made great progress, but there is a certain upper limit to the improvement of the electrical resistance of XLPE. 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 XLPE insulation materials is an effective and easy-to-implement method to improve their 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 introduced voltage stabilizers often contain chromophores, which will be excited under the action of ultraviolet rays. The excited substances will break the carbon-carbon bonds of polyethylene and produce free radicals R·. The free radicals will react with oxygen molecules in the free volume of the polymer to form ROO·, which will then capture hydrogen from the polyethylene molecular chain to form hydrogen peroxide ROOH; the ground state oxygen molecules are in a triplet state, which can extinguish the excited state and form singlet oxygen 1 O 2 , singlet oxygen has strong oxidizing properties and can attack polyethylene molecular chains to form hydroperoxides. In this way, once the photodegradation chain reaction begins, it will quickly lead to the degradation of the polymer. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides an application of 3-cinnamoyl-4-hydroxycoumarin, a cable insulating material and a preparation method thereof. 3-cinnamoyl-4-hydroxycoumarin is used as a voltage stabilizer to prepare the cable insulating material, thereby improving the electrical resistance of the cable insulating material, solving the problem that the voltage stabilizer added to the existing cable insulating material is easily lost during the production, storage and use of the cable, and reducing the effect of the voltage stabilizer, and at the same time solving the problem of photodegradation caused by the action of a high voltage electric field.

[0005] One of the purposes of the present invention is to provide a use of 3-cinnamoyl-4-hydroxycoumarin as a voltage stabilizer in the preparation of cable insulation materials.

[0006] A second object of the present invention is to provide a cable insulation material prepared from 3-cinnamoyl-4-hydroxycoumarin.

[0007] The third object of the present invention is to provide a method for preparing the cable insulation material.

[0008] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0009] In a first aspect, the present invention provides a use of 3-cinnamoyl-4-hydroxycoumarin as shown in Formula 1 as a voltage stabilizer in the preparation of a cable insulation material.

[0010]

[0011] In a second aspect, the present invention provides a cable insulation material prepared from raw materials comprising the following parts by mass: 100 parts of low-density polyethylene, 1.6 to 2.0 parts of diisopropylbenzene peroxide, 0.2 to 0.5 parts of an antioxidant and 0.2 to 1.0 parts of a 3-cinnamoyl-4-hydroxycoumarin grafted voltage stabilizer.

[0012] It should be noted that phr can also be used to express.

[0013] There is no particular limitation on the source of the low-density polyethylene, which can be obtained from the market or prepared by methods known in the art.

[0014] Preferably, the low-density polyethylene has a melt index of 1.80 to 2.10 g / 10 min and a density of 0.91 to 0.93 g / cm 3 .

[0015] The added amount of low-density polyethylene is 100 parts.

[0016] The amount of dicumyl peroxide added is, for example, 1.6, 1.7, 1.8, 1.9, or 2.0 parts.

[0017] 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 pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (Antioxidant 1010).

[0018] The amount of antioxidant added is, for example, 0.2, 0.3, 0.4, or 0.5 parts.

[0019] 3-Cinnamoyl-4-hydroxycoumarin as a voltage stabilizer.

[0020] The amount of the voltage stabilizer added is, for example, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.0 parts. In a third aspect, the present invention provides a method for preparing a cable insulation material, comprising the following steps:

[0021] (a) mixing low-density polyethylene, an antioxidant, and a 3-cinnamoyl-4-hydroxycoumarin grafted voltage stabilizer uniformly to obtain a mixture;

[0022] (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;

[0023] (c) crosslinking and grafting the blended granules obtained in step (b) to obtain a cable insulation material.

[0024] In some embodiments, in step (a), the mixing temperature is 110 to 120° C.;

[0025] In some embodiments, in step (c), the temperature for crosslinking and grafting is 160-270° C., and the pressure is 15-20 MPa.

[0026] Beneficial effects:

[0027] The present invention uses 3-cinnamoyl-4-hydroxycoumarin 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 3-cinnamoyl-4-hydroxycoumarin 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 3-cinnamoyl-4-hydroxycoumarin grafted voltage stabilizer contains an oxonaphthalene ring and a benzene ring, which increases the range of the electron cloud action space. In addition, the hydroxyl group and the carbonyl group have an electron-donating and electron-withdrawing effect, forming an intramolecular charge transfer effect, thereby further enhancing the delocalization of the benzene ring π electrons, and then the energy of high-energy electrons can be consumed more quickly and more efficiently. More importantly, a hydrogen bond is formed between the hydroxyl group and the carbonyl group, and the light energy generated by the high-energy electrons will preferentially destroy the hydrogen bond, thereby avoiding the destruction of the polyethylene molecular chain by the excited state voltage stabilizer molecule. 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.

[0028] 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

[0029] 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.

[0030] Unless otherwise specified, the raw materials, reagents, methods, etc. used in the examples are conventional raw materials, reagents, methods in the art.

[0031] The raw materials involved in the embodiments and comparative examples are as follows:

[0032] 3-Cinnamoyl-4-hydroxycoumarin was purchased from Aladdin Biochemical Technology Co., Ltd.

[0033] The low-density polyethylene comes from Sinopec Qilu Petrochemical Plastics Plant, with a melt index of 2.1 g / 10 min (190 ° C, 2.16 kg) and a density of 0.922 g / cm 3 .

[0034] Example 1

[0035] A 3-cinnamoyl-4-hydroxycoumarin grafted voltage stabilizer modified cross-linked polyethylene cable insulation material, comprising the following components by mass: 100 parts of low-density polyethylene, 2.0 parts of diisopropylbenzene peroxide, 0.2 parts of antioxidant 1010, and 0.2 parts of voltage stabilizer; the low-density polyethylene has a melt index of 2.1 g / 10 min (190° C., 2.16 kg) and a density of 0.922 g / cm 3 ; The voltage stabilizer is 3-cinnamoyl-4-hydroxycoumarin.

[0036] This embodiment provides a method for preparing a cross-linked polyethylene cable insulation material, comprising the following steps:

[0037] (1) Low-density polyethylene, antioxidant 1010, and 3-cinnamoyl-4-hydroxycoumarin grafted voltage stabilizer were mixed and kneaded at 115° C.

[0038] (2) spraying dicumyl peroxide heated to a molten state into the mixture obtained in (1), and then cooling and granulating to obtain blended granules;

[0039] (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.

[0040] Example 2

[0041] A 3-cinnamoyl-4-hydroxycoumarin grafted voltage stabilizer modified cross-linked polyethylene cable insulation material, comprising the following components by mass: 100 parts of low-density polyethylene, 2.0 parts of diisopropylbenzene peroxide, 0.2 parts of antioxidant 1010, and 0.4 parts of voltage stabilizer; the low-density polyethylene has a melt index of 2.1 g / 10 min (190° C., 2.16 kg) and a density of 0.922 g / cm 3 ; The voltage stabilizer is 3-cinnamoyl-4-hydroxycoumarin.

[0042] The preparation method is the same as that of Example 1.

[0043] Example 3

[0044] A 3-cinnamoyl-4-hydroxycoumarin grafted voltage stabilizer modified cross-linked polyethylene cable insulation material, comprising the following components by mass: 100 parts of low-density polyethylene, 2.0 parts of diisopropylbenzene peroxide, 0.2 parts of antioxidant 1010, and 0.6 parts of voltage stabilizer; the low-density polyethylene has a melt index of 2.1 g / 10 min (190° C., 2.16 kg) and a density of 0.922 g / cm 3 ; The voltage stabilizer is 3-cinnamoyl-4-hydroxycoumarin.

[0045] The preparation method is the same as that of Example 1.

[0046] Example 4

[0047] A 3-cinnamoyl-4-hydroxycoumarin grafted voltage stabilizer modified cross-linked polyethylene cable insulation material, comprising the following components by mass: 100 parts of low-density polyethylene, 2.0 parts of diisopropylbenzene peroxide, 0.2 parts of antioxidant 1010, and 0.8 parts of voltage stabilizer; the low-density polyethylene has a melt index of 2.1 g / 10 min (190° C., 2.16 kg) and a density of 0.922 g / cm 3 ; The voltage stabilizer is 3-cinnamoyl-4-hydroxycoumarin.

[0048] The preparation method is the same as that of Example 1.

[0049] Comparative Example 1

[0050] A cross-linked polyethylene cable insulation material, comprising the following components by mass: 100 parts of low-density polyethylene, 2.0 parts of diisopropylbenzene peroxide, and 0.2 parts of antioxidant 1010; the low-density polyethylene has a melt index of 2.1 g / 10 min (190° C., 2.16 kg) and a density of 0.922 g / cm 3 .

[0051] The preparation method is the same as that of Example 1.

[0052] Comparative Example 2

[0053] A 3-acetyl-4-hydroxycoumarin voltage stabilizer modified cross-linked polyethylene cable insulation material, comprising the following components by weight: 100 parts of low-density polyethylene, 2.0 parts of diisopropylbenzene peroxide, 0.2 parts of antioxidant 1010, and 0.42 parts of 3-acetyl-4-hydroxycoumarin voltage stabilizer The low-density polyethylene has a melt index of 2.1 g / 10 min (190° C., 2.16 kg) and a density of 0.922 g / cm 3 .

[0054] The preparation method is the same as that of Example 1.

[0055] Effect Example 1

[0056] The test results of the DC breakdown field strength of the cross-linked polyethylene cable insulation materials of Examples 1 to 4 and Comparative Example 1 are shown in Table 1.

[0057] Test method: The cross-linked polyethylene cable insulation materials of Examples 1 to 4 and Comparative Example 1 were made into circular specimens 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 specimens and electrodes were immersed in silicone oil. The test was carried out at room temperature with a pressurization rate of 0.5 kV / s. The test data were statistically analyzed using Weibull distribution.

[0058] Table 1 DC breakdown field strength table

[0059]

[0060] As shown in Table 1, the DC breakdown field strength of the cross-linked polyethylene cable insulation material increases with the increase in the amount of voltage stabilizer added. When 0.8 parts of 3-cinnamoyl-4-hydroxycoumarin grafted voltage stabilizer is added, the DC breakdown field strength of the cross-linked polyethylene cable insulation material (453kV / mm) is about 24% higher than the DC breakdown field strength of the cross-linked polyethylene cable insulation material without adding voltage stabilizer (366kV / mm). It can be seen that adding 3-cinnamoyl-4-hydroxycoumarin grafted voltage stabilizer can improve the DC insulation performance of the cross-linked polyethylene cable insulation material.

[0061] Effect Example 2

[0062] The current density values ​​of the cross-linked polyethylene cable insulation materials of Example 3 and Comparative Examples 1-2 at an electric field strength of 20 kV / mm were tested. The test results are shown in Table 2.

[0063] Test method: The cross-linked polyethylene cable insulation materials of Example 3 and Comparative Examples 1-2 are made into samples with a thickness of 200 μm and a side length of 10 cm×10 cm, and the test field strength is 20 kV / mm, the measuring pole diameter is 50 mm, the inner diameter of the protective pole is 54 mm, the outer diameter is 74 mm, and the high-voltage pole diameter is 76 mm. The sample and the electrode are placed in a shielding box, and the field strength is gradually increased by 5 kV / 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.

[0064] Table 2 Current density table

[0065] Example 3 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 ]]>

[0066] As can be seen from Table 2, adding 0.6 parts of 3-cinnamoyl-4-hydroxycoumarin grafted 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, compared with the current density value of the cross-linked polyethylene cable insulation material with 0.42 parts of 3-acetyl-4-hydroxycoumarin voltage stabilizer (0.6 parts of 3-cinnamoyl-4-hydroxycoumarin grafted voltage stabilizer contains 0.42 parts of 3-acetyl-4-hydroxycoumarin units), it is one order of magnitude lower. This shows that the 3-cinnamoyl-4-hydroxycoumarin grafted voltage stabilizer can be more evenly distributed in the material through the grafting reaction, inhibiting the field conductivity and reducing the serious negative impact of the naphthoquinone voltage stabilizer on the conductivity of the cross-linked polyethylene.

[0067] Effect Example 3

[0068] The test results of the UV aging test of the cross-linked polyethylene cable insulation material of Examples 1 to 4 and Comparative Example 1 are shown in Table 3. The sample preparation was carried out according to GB / T 2951.21, with a temperature of 200°C, a load of 0.2 MPa, a time of 15 min, a small dumbbell-shaped specimen, and a gauge length of 10 mm.

[0069] Test method: Expose the sample to a UV light source for UV aging test, and measure the change in tensile strain at break of the sample before and after aging. The exposure conditions are designed with reference to GB / T 16422.3-2022 "Plastic Laboratory Light Source Exposure Test Method Part 3: Fluorescent UV Lamp", the fluorescent lamp model is UVA-340, the wavelength range is 295-365nm, the humidity range is 45%-98%RH, the illumination temperature range is 50℃-70℃, the condensation temperature range is 40℃-60℃, and the radiation is 0.76W / m 2 , put the sample into the test box and take samples in stages.

[0070] Table 3 Breaking tensile strain table

[0071]

[0072] As shown in Table 3, the tensile strain at break of Examples 1 to 4 and Comparative Example 1 is about 490% when not subjected to UV aging treatment. When irradiated with UV light for 2 days, the tensile strain at break of Examples 1 to 4 is about 400%, with a change rate of 18.9%, 18.8%, 19.6% and 22.5%, respectively. The tensile strain at break of Comparative Example 1 is 241%, with a change rate of 51%. When irradiated with UV light for 4 days and 6 days, the tensile strain at break of Comparative Example 1 basically does not change, with a change rate of about 92%. However, for Examples 1 to 4, when irradiated with UV light for 4 days, the change rates of tensile strain at break are about 48%, 44%, 45% and 40%, respectively. When irradiated with UV light for 6 days, the change rates of tensile strain at break are about 70%, 69%, 67% and 66%, respectively. This indicates that with the increase of voltage stabilizer, the change rate of tensile strain at break of the sample slows down, and the anti-UV aging ability of Examples 1 to 4 is significantly better than that of Comparative Example 1.

[0073] 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. Use of 3-cinnamoyl-4-hydroxycoumarin as shown in formula 1 as a voltage stabilizer in the preparation of cable insulation materials, 2. A 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, 1.6-2.0 parts of dicumyl peroxide, 0.2-0.5 parts of antioxidant and 0.2-1.0 parts of 3-cinnamoyl-4-hydroxycoumarin grafted voltage stabilizer.

3. The cable insulation material according to claim 2, characterized in that: The low-density polyethylene has a melt index of 1.80 to 2.10 g / 10 min and a density of 0.91 to 0.93 g / cm 3 .

4. The cable insulation material according to claim 2, 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).

5. The cable insulation material according to claim 4, characterized in that: The antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

6. A method for preparing a cable insulation material according to any one of claims 2 to 5, characterized in that: The following steps are involved: (a) mixing low-density polyethylene, an antioxidant, and a 3-cinnamoyl-4-hydroxycoumarin grafted 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 cable insulation material.

7. The preparation method according to claim 6, characterized in that: In step (a), the mixing temperature is 110-120°C.

8. The preparation method according to claim 6, characterized in that: In step (c), the temperature for crosslinking and grafting is 160-270°C.

9. The preparation method according to claim 6, characterized in that: In step (c), the pressure of crosslinking and grafting is 15 to 20 MPa.

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