Medium-voltage cable for photovoltaic power generation

Abstract

The invention provides a medium-voltage cable for photovoltaic power generation, which is prepared from the following raw materials in parts by mass: 15 to 30 parts of styrene-ethylene-butylene-styrene block copolymer, 15 to 30 parts of ethylene propylene rubber, 10 to 20 parts of polyethylene, 10 to 30 parts of brominated epoxy resin, 20 to 40 parts of magnesium hydroxide, 5 to 10 parts of vinyl trimethoxy silane, 1 to 5 parts of hindered phenol antioxidant additive and 1 to 3 parts of diluent. And 0.1-1 part of a vulcanizing agent. By designing the raw material formula, the interaction among the components in the raw material composition jointly endows the cable with a series of beneficial effects, and the effects are crucial for ensuring the reliable operation of the cable in a photovoltaic system.

Description

Technical Field

[0001] The present invention belongs to the technical field of cables for photovoltaic power generation, and particularly relates to a medium-voltage cable for photovoltaic power generation. Background Art

[0002] As an important part of renewable energy, photovoltaic power generation has developed rapidly worldwide in recent years. As a key component in a photovoltaic power generation system, a photovoltaic cable undertakes the important task of transmitting electric energy. Especially in medium-voltage power transmission, the performance and quality of a photovoltaic cable are directly related to the safety and reliability of the entire photovoltaic power generation system.

[0003] A photovoltaic cable needs to be exposed to the outdoor environment for a long time and is affected by natural environments such as ultraviolet rays, high temperature, low temperature, and humidity. In some special environments, such as saline-alkali land and near chemical plants, the cable may also be corroded by chemical substances. Therefore, the conductor and outer sheath of the cable need to have good corrosion resistance, weather resistance, and anti-aging performance to extend the service life of the cable.

[0004] To improve the weather resistance and anti-aging performance of the cable, high molecular materials such as cross-linked polyethylene (XLPE), ethylene-vinyl acetate copolymer (EVA), and thermoplastic polyurethane (TPU) are widely used as the insulating layer and outer sheath of the cable in the prior art. These materials have excellent ultraviolet resistance, high and low temperature resistance, and moisture resistance, and can effectively resist the erosion of the outdoor environment. Although the high-performance materials in the prior art already have relatively high weather resistance and anti-aging performance, their performance may still decline in extreme environments (such as extreme high temperature, low temperature, and strong ultraviolet radiation). In addition, chemical substances in some special environments may have unknown corrosive effects on the existing materials. Summary of the Invention

[0005] The purpose of this part is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this part, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this part, the abstract, and the title. However, such simplifications or omissions shall not be used to limit the scope of the present invention.

[0006] In view of the above and / or problems existing in the prior art, the present invention is proposed.

[0007] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a medium-voltage cable for photovoltaic power generation.

[0008] To solve the above technical problems, the present invention provides the following technical solutions: calculated by mass parts of the raw materials of the medium-voltage cable, including,

[0009] 15 - 30 parts of styrene - ethylene - butene - styrene block copolymer, 15 - 30 parts of ethylene - propylene rubber, 10 - 20 parts of polyethylene, 10 - 30 parts of brominated epoxy resin, 20 - 40 parts of magnesium hydroxide, 5 - 10 parts of vinyltrimethoxysilane, 1 - 5 parts of hindered phenol antioxidant auxiliary agent, 1 - 3 parts of diluent, 0.1 - 1 part of vulcanizing agent.

[0010] Preferably, among them: the brominated epoxy resin is EP - type brominated epoxy resin, and the relative molecular mass is 8000 - 25000.

[0011] Preferably, among them: the hindered phenol antioxidant auxiliary agent includes one or more of poly - hindered phenol antioxidant 1010, 1076, 1098, 1330, 3114.

[0012] Preferably, among them: the diluent is ethyl acetate.

[0013] Preferably, among them: the vulcanizing agent is 2,5 - dimethyl - 2,5 - bis(tert - butylperoxy)hexane.

[0014] Another object of the present invention is to provide a preparation method of a medium - voltage cable for photovoltaic power generation.

[0015] To solve the above - mentioned technical problems, the present invention provides the following technical solutions: including,

[0016] Stir and mix brominated epoxy resin, magnesium hydroxide, vinyltrimethoxysilane, and diluent under high - temperature conditions to obtain mixture I;

[0017] Mix and knead mixture I with styrene - ethylene - butene - styrene block copolymer, ethylene - propylene rubber, polyethylene, and hindered phenol antioxidant auxiliary agent under pressurized conditions to obtain mixture II;

[0018] Put mixture II into a twin - screw extruder for co - extrusion, and add a vulcanizing agent during the extrusion process to extrude and obtain a medium - voltage cable.

[0019] Preferably, among them: the stirring speed of the stirring and mixing under high - temperature conditions is 2000 - 3000 rpm, and the stirring temperature is 150 - 160 °C.

[0020] Preferably, among them: the pressure of the stirring and kneading under pressurized conditions is 2 - 5 MPa, and the kneading temperature is 150 - 200 °C.

[0021] Preferably, wherein: the extrusion temperature for the co - blending extrusion is as follows: the first zone is 130 - 145 °C, the second zone is 130 - 145 °C, the third zone is 130 - 145 °C, the fourth zone is 130 - 145 °C, the fifth zone is 130 - 145 °C, the sixth zone is 130 - 145 °C, the seventh zone is 130 - 145 °C, the eighth zone is 130 - 145 °C, the ninth zone is 130 - 145 °C, and the die head is 140 - 155 °C.

[0022] Preferably, wherein: during the co - blending extrusion, the pressure of the vacuum pump is set to 0.1 - 0.2 ATM.

[0023] Advantages of the present invention:

[0024] The present invention provides a medium - voltage cable for photovoltaic power generation. The interactions between the components in the raw material composition jointly endow the cable with a series of beneficial effects. These interactions mainly include:

[0025] Styrene - ethylene - butene - styrene block copolymer (SEBS), as a thermoplastic elastomer, when used in combination with ethylene - propylene rubber (EPR), can provide good elasticity and flexibility, while maintaining good strength, which helps the durability of the cable in complex environments. It can also improve the toughness of polyethylene (PE) and enhance the impact resistance of the cable.

[0026] Brominated epoxy resin and magnesium hydroxide are both flame retardants with excellent flame - retardant properties. There is a synergistic flame - retardant effect between them. The combination of the two can significantly improve the flame - retardant performance of the cable and reduce the fire risk. In addition, brominated epoxy resin may decompose to generate free radicals at high temperatures, and the polyhydric hindered phenol antioxidant 1010, as an antioxidant, can capture these free radicals to prevent the aging and degradation of the cable material.

[0027] These effects are crucial for ensuring the reliable operation of the cable in the photovoltaic system. Detailed implementation manners

[0028] To make the above - mentioned objects, features, and advantages of the present invention more obvious and understandable, the following detailed description of the specific implementation manners of the present invention is made in conjunction with the embodiments of the specification.

[0029] Unless otherwise specified, the raw materials used in the present invention are all ordinary commercially available analytical pure in the art.

[0030] The styrene - ethylene - butene - styrene block copolymer is purchased from Dongguan Huibai Plastic Raw Material Co., Ltd., with the product number 7131, and the melt flow rate (melt mass - flow rate) (230 °C / 5.0 kg);

[0031] The ethylene - propylene rubber is purchased from Shanghai Oshuo Plastic Co., Ltd., with the product number IP 4640; the polyethylene is purchased from Shanghai Oshuo Plastic Co., Ltd., with the product number 80064;

[0032] The brominated epoxy resin was purchased from Zhongshan Dixin Chemical Co., Ltd., with a CAS number of 68928-70-1;

[0033] Unless otherwise specified, the remaining raw materials are commonly commercially available in this field.

[0034] The performance test method for the cable prepared in the present invention:

[0035] Refer to the standard IEC 60167 to measure the volume resistivity of the cable at 20°C / Ω·cm;

[0036] Refer to the standard IEC 60811 to measure the tensile strength / MPa and the elongation at break / %;

[0037] Refer to the standard ISO 6722 to measure the abrasion resistance;

[0038] Refer to the standard ISO 4589-2 to measure the oxygen index / %;

[0039] The weather resistance is characterized by measuring the change rates of the tensile strength / MPa and the elongation at break / % of the cable after heat aging treatment at 100°C for 240 h.

[0040] Example 1

[0041] This example provides a preparation method for a medium-voltage cable for photovoltaic power generation. Specifically:

[0042] 1) Weigh the raw materials according to the following components:

[0043] 15 parts of styrene-ethylene-butene-styrene block copolymer, 30 parts of ethylene-propylene rubber, 15 parts of polyethylene, 20 parts of brominated epoxy resin, 30 parts of magnesium hydroxide, 8 parts of vinyltrimethoxysilane, 3 parts of a hindered phenol antioxidant (multi-functional hindered phenol antioxidant 1010), 3 parts of a diluent (ethyl acetate), 0.5 part of a vulcanizing agent (2,5-dimethyl-2,5-di(tert-butylperoxy)hexane);

[0044] 2) Preparation of the cable material:

[0045] The brominated epoxy resin and magnesium hydroxide were mixed and put into a high-speed mixer. Set the rotation speed to 2500 rpm and the temperature to 150°C. During this period, vinyltrimethoxysilane and ethyl acetate were slowly added. After all were added, mix at 3000 rpm for 10 min to obtain mixture I;

[0046] Mixture I, styrene-ethylene-butene-styrene block copolymer, ethylene-propylene rubber, polyethylene, and the hindered phenol antioxidant were put into a pressure kneader. Control the pressure to 4 MPa and the temperature to 180°C, and knead for 45 min to make each component evenly mixed to obtain mixture II;

[0047] The mixture II was put into a twin-screw extruder for blending and extrusion. The temperatures of the twin-screw extruder were as follows: the first zone was 130 °C, the second zone was 130 °C, the third zone was 135 °C, the fourth zone was 135 °C, the fifth zone was 140 °C, the sixth zone was 140 °C, the seventh zone was 140 °C, the eighth zone was 145 °C, the ninth zone was 145 °C, and the die head was 150 °C. The pressure of the vacuum pump was set to 0.1 ATM. 2,5-Dimethyl-2,5-bis(tert-butylperoxy)hexane was added through side feeding in the third zone, and a vulcanizing agent was added during the extrusion process to obtain a medium-voltage cable.

[0048] Example 2

[0049] The difference between this example and Example 1 was that the raw material formula was adjusted as follows:

[0050] 20 parts of styrene-ethylene-butene-styrene block copolymer, 15 parts of ethylene-propylene rubber, 20 parts of polyethylene, 10 parts of brominated epoxy resin, 20 parts of magnesium hydroxide, 5 parts of vinyltrimethoxysilane, 1 part of a hindered phenol antioxidant (multi-hindered phenol antioxidant 1010), 1 part of a diluent (ethyl acetate), and 0.1 part of a vulcanizing agent (2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane);

[0051] The remaining process steps were all referred to Example 1 to obtain the medium-voltage cable of this example.

[0052] Example 3

[0053] The difference between this example and Example 1 was that the raw material formula was adjusted as follows:

[0054] 25 parts of styrene-ethylene-butene-styrene block copolymer, 25 parts of ethylene-propylene rubber, 10 parts of polyethylene, 30 parts of brominated epoxy resin, 30 parts of magnesium hydroxide, 10 parts of vinyltrimethoxysilane, 5 parts of a hindered phenol antioxidant (multi-hindered phenol antioxidant 1010), 3 parts of a diluent (ethyl acetate), and 1 part of a vulcanizing agent (2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane);

[0055] The remaining process steps were all referred to Example 1 to obtain the medium-voltage cable of this example.

[0056] Comparative Example 1

[0057] The difference between this comparative example and Example 1 was that the brominated epoxy resin in the raw materials was omitted and replaced with an equal amount of magnesium hydroxide. The remaining process steps were all referred to Example 1 to obtain the medium-voltage cable of this comparative example.

[0058] Comparative Example 2

[0059] The difference between this comparative example and Example 1 is that magnesium hydroxide in the raw materials is omitted and replaced with an equal amount of brominated epoxy resin. The remaining steps and processes are all referred to Example 1 to obtain the medium-voltage cable of this comparative example.

[0060] Comparative Example 3

[0061] The difference between this comparative example and Example 1 is that vinyltrimethoxysilane in the raw materials is omitted. The remaining steps and processes are all referred to Example 1 to obtain the medium-voltage cable of this comparative example.

[0062] The relevant properties of the medium-voltage cables prepared in Example 1 and Comparative Examples 1 to 3 were measured, and the results are shown in Table 1.

[0063] Table 1 Statistical results of performance test for omitting vinyltrimethoxysilane in raw materials

[0064]

[0065] As can be seen from Table 1, the cable obtained under the formula of the present invention has the optimal performance. In the solution of the present invention, there is a synergistic effect between brominated epoxy resin and magnesium hydroxide. Brominated epoxy resin is an efficient flame retardant, which can release bromine free radicals during combustion, thus inhibiting the spread of the flame; magnesium hydroxide is also an effective flame retardant, which can decompose to produce water vapor at high temperature, thus diluting combustible gases and reducing the combustion temperature. The two act synergistically to jointly improve the flame retardant performance of the cable. Vinyltrimethoxysilane, as a coupling agent, is crucial for improving the adhesion and overall performance between different materials in the solution of the present invention. Omitting it will lead to a decrease in the interaction force between materials, thus affecting the mechanical properties and weather resistance of the cable.

[0066] Comparative Example 4

[0067] The difference between this comparative example and Example 1 is that vinyltrimethoxysilane is adjusted to tridecyl alcohol polyoxyethylene ether phosphate, silane coupling agent KH-570, and titanate coupling agent respectively. The remaining steps and processes are all referred to Example 1 to obtain the cables of this comparative example, denoted as D4-1, D4-2, and D4-3 respectively, and compared with Example 1. The results are shown in Table 2.

[0068] Table 2 Statistical results of performance test for adjusting vinyltrimethoxysilane to other components

[0069]

[0070] As can be seen from Table 2, in the solution of the present invention, vinyltrimethoxysilane (VTMS) plays an important role. Through its unique functional group structure, namely vinyl and hydrolyzable methoxy groups, it interacts with other components in the cable, thereby significantly improving the mechanical properties, electrical properties, weather resistance and flame retardancy of the cable.

[0071] The methoxy functional group of VTMS can react with the hydroxyl groups on the surface of magnesium hydroxide to form chemical bonding, thereby improving the dispersibility and adhesion of inorganic fillers in the polymer matrix, and reacting with double bonds or other active functional groups in the polymer matrix (such as styrene-ethylene-butene-styrene block copolymer, ethylene-propylene rubber, polyethylene) to form covalent bonds or crosslinked structures, thereby enhancing the mechanical properties and electrical properties of the cable. In addition, the introduction of VTMS can also improve the antioxidant performance and weather resistance of the cable, which may be related to its ability to form a protective film on the surface of the cable.

[0072] When VTMS is replaced with other surfactants, such as tridecanol polyoxyethylene ether phosphate as a non-ionic surfactant, it is mainly used to improve the wettability and dispersibility of materials, but lacks the ability to form chemical bonding with inorganic fillers and polymer matrices; although KH-570 is also a silane coupling agent, there are differences in its functional group structure from VTMS. KH-570 contains methoxysilane and acryloyloxy functional groups. Among them, the acryloyloxy group may react with the double bond in the polymer matrix, but the reaction activity of methoxysilane with inorganic fillers may be lower than that of the methoxy group of VTMS. In addition, the spatial structure and reaction activity of KH-570 may also be different from those of VTMS, resulting in a decrease in the performance of the cable after replacement. The titanate coupling agent mainly forms chemical bonding through the alkoxy groups on its titanium atom reacting with the hydroxyl groups on the surface of inorganic fillers, and its bonding ability is much lower than that of vinyltrimethoxysilane.

[0073] Example 4

[0074] The difference between this example and Example 1 is that the dosages of vinyltrimethoxysilane are adjusted to 2 parts, 5 parts, 8 parts, 10 parts, and 12 parts respectively, and the remaining process steps are all referred to Example 1 to obtain the cable of this example. Comparing with Example 1 (8 parts), the results are shown in Table 3.

[0075] Table 3 Test results of the dosage of vinyltrimethoxysilane on the cable performance

[0076]

[0077] As can be seen from Table 3, the dosage of vinyltrimethoxysilane also has a significant impact on the cable performance. Vinyltrimethoxysilane is a colorless and transparent liquid with an ester odor. Its molecular structure contains a vinyl functional group with an unsaturated double bond structure and three hydrolyzable methoxy groups. This dual reactivity enables it to enhance the bonding, adhesion, and compatibility between inorganic materials and organic polymers through bidirectional chemical reactions with them. Specifically, it can act as a coupling agent, adhesion promoter, crosslinking agent, surface modifier, etc. in the present invention.

[0078] The vinyl functional group of vinyltrimethoxysilane may interact with certain parts of the styrene-ethylene-butene-styrene block copolymer, thereby improving the overall performance. However, this interaction may not always be beneficial to the improvement of cable performance. Therefore, when the dosage of vinyltrimethoxysilane increases, it may disrupt the original performance balance of SEBS, resulting in a decrease in cable performance.

[0079] When vinyltrimethoxysilane is used as a crosslinking agent or coupling agent, it may help improve the compatibility between ethylene-propylene rubber and inorganic fillers or other polymers. However, excessive vinyltrimethoxysilane may interfere with the crosslinking process of ethylene-propylene rubber, leading to a decrease in the degree of crosslinking and thus affecting the mechanical properties of the cable.

[0080] Vinyltrimethoxysilane can react with functional groups such as hydroxyl or carboxyl groups in polyethylene to improve the bonding strength and water resistance of polyethylene. However, excessive vinyltrimethoxysilane may cause changes in the molecular chain structure of polyethylene, thereby affecting its original performance.

[0081] Vinyltrimethoxysilane can react with the hydroxyl groups on the surface of magnesium hydroxide to improve the compatibility and bonding strength between inorganic fillers and polymers. However, excessive vinyltrimethoxysilane may cause the dispersion of magnesium hydroxide in the polymer to deteriorate, thereby affecting the flame retardant performance of the cable.

[0082] Comparative Example 5

[0083] The difference between this comparative example and Example 1 is that the brominated epoxy resin is adjusted to pentabromobenzyl acrylate, brominated styrene-butadiene-styrene copolymer, and brominated polystyrene respectively. The remaining process steps are all referred to Example 1 to obtain the cables of this comparative example, denoted as D5-1, D5-2, and D5-3 respectively. Comparing with Example 1, the results are shown in Table 4.

[0084] Table 4 Statistical Results of Performance Tests for Adjusting Brominated Epoxy Resin to Other Components

[0085]

[0086] As can be seen from Table 4, the selection of brominated epoxy resin in the present invention has a significant impact on the overall performance of the cable. This is because the brominated epoxy resin has good compatibility with SEBS, and both contain styrene structural units, which helps to form good interfacial bonding force when they are mixed. Moreover, there is a synergistic flame retardant effect between it and magnesium hydroxide. The combined use of the two can significantly improve the flame retardant performance of the cable. When the brominated epoxy resin is replaced with other flame retardants of the same type, due to the structural differences, the compatibility with the matrix polymer becomes poor, thus affecting the overall performance.

[0087] In summary, the present invention provides a medium-voltage cable for photovoltaic power generation. The interactions among the components in the raw material composition jointly endow the cable with a series of beneficial effects. These interactions mainly include:

[0088] Styrene-ethylene-butene-styrene block copolymer (SEBS), as a thermoplastic elastomer, when used in combination with ethylene-propylene rubber (EPR), can provide good elasticity and flexibility, while maintaining good strength, which helps the durability of the cable in complex environments. It can also improve the toughness of polyethylene (PE) and enhance the impact resistance of the cable.

[0089] Both brominated epoxy resin and magnesium hydroxide are flame retardants with excellent flame retardant properties. There is a synergistic flame retardant effect between the two, and their combination can significantly improve the flame retardant performance of the cable and reduce the fire risk. In addition, brominated epoxy resin may decompose to generate free radicals at high temperatures, and the multi-functional hindered phenol antioxidant 1010 can capture these free radicals to prevent the aging and degradation of the cable material.

[0090] These effects are crucial for ensuring the reliable operation of the cable in the photovoltaic system.

[0091] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not restrictive. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A medium voltage cable for photovoltaic power generation, characterized in that: Measured by mass percentage of medium voltage cable raw materials, including: 15-30 parts of styrene-ethylene-butylene-styrene block copolymer, 15-30 parts of ethylene-propylene rubber, 10-20 parts of polyethylene, 10-30 parts of brominated epoxy resin, 20-40 parts of magnesium hydroxide, 5-10 parts of vinyl trimethoxy silane, 1-5 parts of hindered phenol antioxidant, 1-3 parts of diluent, and 0.1-1 part of vulcanizing agent.

2. The medium voltage cable for photovoltaic power generation according to claim 1, characterized in that: The brominated epoxy resin is an EP type brominated epoxy resin with a relative molecular mass of 8000 to 25000.

3. The medium voltage cable for photovoltaic power generation according to claim 1, characterized in that: The hindered phenol antioxidant aid includes one or more of the polyhydric hindered phenol antioxidants 1010, 1076, 1098, 1330, and 3114.

4. The medium voltage cable for photovoltaic power generation according to claim 1, characterized in that: The diluent is ethyl acetate.

5. The medium voltage cable for photovoltaic power generation according to claim 1, characterized in that: The vulcanizing agent is 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

6. The method for preparing a medium voltage cable according to any one of claims 1 to 5, characterized in that: include, The brominated epoxy resin, magnesium hydroxide, vinyl trimethoxy silane and a diluent are stirred and mixed under high temperature conditions to obtain a mixture I; Mixture I is stirred and kneaded with styrene-ethylene-butylene-styrene block copolymer, ethylene-propylene rubber, polyethylene and hindered phenol antioxidant under pressure to obtain mixture II; The mixture II is put into a twin-screw extruder for blending and extrusion, and a vulcanizing agent is added during the extrusion process to obtain a medium-voltage cable.

7. The method for preparing a medium voltage cable according to claim 6, characterized in that: The stirring speed of the stirring and mixing under the high temperature condition is 2000-3000 rpm, and the stirring temperature is 150-160°C.

8. The method for preparing a medium voltage cable according to claim 6, characterized in that: The pressure of stirring and kneading under the pressurized conditions is 2-5 MPa, and the kneading temperature is 150-200°C.

9. The method for preparing a medium voltage cable according to claim 6, characterized in that: The extrusion temperature of the blending extrusion is 130-145°C in the first zone, 130-145°C in the second zone, 130-145°C in the third zone, 130-145°C in the fourth zone, 130-145°C in the fifth zone, 130-145°C in the sixth zone, 130-145°C in the seventh zone, 130-145°C in the eighth zone, 130-145°C in the ninth zone, and 140-155°C at the die head.

10. The method for preparing a medium voltage cable according to claim 9, characterized in that: During the co-extrusion process, the vacuum pump pressure is set at 0.1-0.2 ATM.

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