Novel cable semi-conductive buffer layer and preparation method thereof

Abstract

The invention discloses a novel cable semi-conductive buffer layer and a preparation method thereof, and relates to the field of electrical materials. The semi-conductive buffer layer comprises a semi-conductive buffer strip and a rubber coating located on the surface of the semi-conductive buffer strip, the semi-conductive buffer strip is a semi-conductive water-blocking tape or a semi-conductive nylon tape, and the rubber coating comprises butyl rubber, a conductive filler, a functional additive, paraffin and a vulcanizing agent. In order to solve the technical problem of poor water resistance of the cable semi-conductive buffer layer, the rubber coating is arranged on the surface of the semi-conductive buffer strip, butyl rubber in the rubber coating has good air tightness, permeation of water molecules is effectively prevented, the risk of breakdown does not exist when the cable runs in a humid environment for a long time, and the service life of the cable is prolonged. And the conductive filler is uniformly dispersed in the rubber coating, so that the volume resistivity and the surface resistance of the buffer layer can be maintained or reduced, the conductivity and the field intensity homogenization effect are good, and the application requirements are met.

Description

Technical Field

[0001] The present invention relates to the field of electrical materials, and particularly to a novel semi-conductive buffer layer for cables and a preparation method thereof. Background Art

[0002] In the design of the buffer layer of high-voltage cables, uneven distribution of electric field stress is a prominent problem. This uneven distribution often leads to ablation phenomena and the appearance of white spots. The main function of the buffer layer is to evenly distribute the electric field stress during the operation of the cable, thereby preventing electrical breakdown and protecting the internal insulating layer from damage. Under harsh external conditions, such as when the cable is exposed to moisture, it is extremely easy to cause uneven distribution of electric field stress. Some areas may bear excessive electric field stress, which may then lead to local breakdown or overall breakdown, thus triggering cable failures and damages. Therefore, it is particularly important to improve the electrical performance of the buffer layer.

[0003] Cable buffer layer tapes, such as semi-conductive non-woven fabrics, semi-conductive water-blocking tapes, and semi-conductive nylon tapes, play an important role in the cable buffer layer. Their main functions include: achieving uniform distribution of the electric field between the insulating layer and the metal sheath of the cable through the voltage equalization effect, significantly reducing the electric field gradient, thereby reducing the risk of partial discharge and breakdown; they also extend the service life of the cable, reduce insulation aging caused by electric field stress, and improve the reliability and durability of the cable. Currently, the moisture resistance of cable buffer tapes is poor, and there is a risk of breakdown under long-term moisture through the water-blocking powder method, and the tensile strength of the buffer tapes is not high enough. Therefore, it is still somewhat difficult to improve the water-blocking and tensile strength of the buffer tapes while ensuring good electrical performance. Summary of the Invention

[0004] The present invention provides a novel semi-conductive buffer layer for cables and a preparation method thereof to solve the technical problems that the current cable buffer layer tapes have poor water-blocking performance and a high risk of breakdown in a moisture environment. By coating a rubber coating containing conductive fillers on the surface of the semi-conductive tape, the rubber coating has excellent water-blocking properties, can simultaneously improve the tensile strength, is not easily broken down in a moisture environment, and maintains the electrical performance.

[0005] To solve the above technical problems, one of the objectives of the present invention is to provide a novel semi-conductive buffer layer for cables, which includes a semi-conductive buffer tape and a rubber coating located on the surface of the semi-conductive buffer tape. The semi-conductive buffer tape is a semi-conductive water-blocking tape or a semi-conductive nylon tape, and the rubber coating includes the following components in parts by weight:

[0006] Butyl rubber: 300 parts;

[0007] Conductive filler: 150 - 180 parts;

[0008] Functional additive: 13 - 30 parts;

[0009] Paraffin wax: 15 - 20 parts;

[0010] Vulcanizing agent: 4 - 7 parts;

[0011] The functional aid includes zinc oxide, magnesium oxide and calcium oxide with a mass ratio of 4:(0.5 - 1):(0.5 - 1).

[0012] In order to improve the water resistance and tensile strength of the cable buffer strip, in this application, by setting a rubber coating containing butyl rubber on the semiconductive buffer strip, a waterproof layer can be formed. Its water resistance is mainly based on the excellent water resistance, resistance to polar liquids and chemical structure of butyl rubber. The high - molecular structure of butyl rubber gives it good airtightness, effectively preventing the penetration of water molecules. It will not have the risk of being broken down when operating in a long - term humid environment, improving the electrical performance, obtaining a cable buffer layer material with more excellent tensile strength and water resistance, and conductive fillers are uniformly dispersed in the rubber coating, so that the buffer layer material still has a low volume resistivity and surface resistance, ensuring the electrical performance of the buffer layer material.

[0013] As a preferred solution, the rubber coating further includes 3 - 9 parts by weight of antioxidant.

[0014] As a preferred solution, the rubber coating further includes 1 - 6 parts by weight of vulcanization accelerator.

[0015] As a preferred solution, the vulcanization accelerator includes 2 - 4 parts by weight of accelerator TMTD and 1 - 2 parts by weight of accelerator M.

[0016] As a preferred solution, the functional aid includes zinc oxide, magnesium oxide and calcium oxide with a mass ratio of 4:0.5:0.5.

[0017] As a preferred solution, the conductive filler is at least one of carbon black, carbon nanotubes, graphene, graphite, and nano - metallic elements.

[0018] As a preferred solution, the antioxidant is N - cyclohexyl - N'- phenyl - p - phenylenediamine.

[0019] As a preferred solution, the vulcanizing agent is sulfur.

[0020] As a preferred solution, the thickness of the semiconductive buffer strip is 0.1 - 1 mm.

[0021] In order to solve the above - mentioned technical problems, the second object of the present invention is to provide a preparation method of a new - type cable semiconductive buffer layer, including the following steps:

[0022] (1) Cut the butyl rubber composite masterbatch into rubber particles, add No. 120 solvent naphtha, stir for 4 - 10 h, and then stir while heating in a water bath for 4 - 8 h to obtain a rubber solution;

[0023] (2) Coating a rubber solution on the surface of the semi-conductive buffer strip, drying and vulcanizing to form a rubber coating, thus obtaining a buffer layer.

[0024] As a preferred solution, in step (1), the preparation method of the butyl rubber composite mixed rubber is as follows: Add butyl rubber to an open mill, after plasticizing evenly, add functional additives, anti-aging agents, and paraffin and mix evenly. Subsequently, add carbon black in several batches, mix evenly, and finally add vulcanizing agents and vulcanization accelerators and mix evenly. Adjust the roll gap to thin the rubber sheet and take it off to obtain the butyl rubber composite mixed rubber.

[0025] In this application, the prepared butyl rubber composite mixed rubber is heated and dissolved with No. 120 solvent oil, and then evenly applied on the semi-conductive buffer strip. After curing, a water-blocking layer is formed, improving the water-blocking ability of the semi-conductive buffer strip. The rubber coating also has a certain elasticity and strength, improving the overall tensile strength of the buffer layer. At the same time, after applying a relatively thin rubber coating, the buffer layer tape still ensures high conductivity, with both volume resistivity and surface resistance being relatively low, verifying the feasibility of the solution.

[0026] As a preferred solution, in the preparation method of the butyl rubber composite mixed rubber, the rotor speed of the open mill is adjusted to 20 - 40 r / min.

[0027] As a preferred solution, in the preparation method of the butyl rubber composite mixed rubber, the plasticizing time is 2 - 5 min.

[0028] As a preferred solution, in the preparation method of the butyl rubber composite mixed rubber, the total mixing time is 10 - 20 min.

[0029] As a preferred solution, in step (1), the mass ratio of the rubber material to No. 120 solvent oil is (10 - 20):(80 - 90).

[0030] As a preferred solution, in step (1), the water bath heating temperature is 40 - 60 °C.

[0031] As a preferred solution, in step (2), the coating thickness of the rubber solution is 0.02 - 0.08 mm.

[0032] As a preferred solution, in step (2), the drying temperature is 60 - 100 °C, and the drying time is 5 - 15 min.

[0033] As a preferred solution, in step (2), the vulcanization temperature is 150 - 180 °C, and the vulcanization time is 5 - 15 min.

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

[0035] In order to solve the technical problem of poor water-blocking performance of the semi-conductive buffer layer of the cable, a rubber coating is provided on the surface of the semi-conductive buffer strip. The rubber coating contains butyl rubber material, and its polymer structure enables the rubber coating to have good airtightness, effectively preventing the penetration of water molecules. There is no risk of breakdown during long-term operation in a humid environment, improving the electrical performance. Moreover, the rubber coating can provide a certain strength for the semi-conductive buffer strip, improving the tensile strength of the overall buffer layer. Conductive fillers are evenly dispersed in the rubber coating, which has excellent conductive properties, does not affect the conductivity of the semi-conductive buffer strip, can maintain or reduce the volume resistivity and surface resistance of the buffer layer, has good conductive ability and homogenizing field strength effect, and meets the application requirements. Description of the Drawings

[0036] Figure 1 : Statistical chart of the volume resistivity of the semi-conductive buffer layer of the cable in Comparative Examples 7-11 of the present invention varying with temperature;

[0037] Figure 2 : Cross-sectional scanning electron microscope image of the butyl rubber composite compound prepared in Preparation Example 3 of the present invention (Note: Scale 10μm);

[0038] Figure 3 : Cross-sectional scanning electron microscope image of the butyl rubber composite compound prepared in Preparation Example 3 of the present invention (Note: Scale 5μm). Detailed Embodiments

[0039] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0040] It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded within the range.

[0041] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although this invention has been described only in terms of preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of this invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with those documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0042] As used herein, the terms:

[0043] "prepared from" is synonymous with "comprising". The terms "comprising", "including", "having", "containing", or any other variation thereof used herein are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that comprises the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0044] The connecting phrase "consisting of" excludes any unrecited element, step, or component. If used in a claim, this phrase renders the claim closed, excluding materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the claim body rather than immediately following the subject, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0045] When an equivalent, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values and lower preferred values, this should be understood to specifically disclose all ranges formed by any pairing of any upper range limit or preferred value with any lower range limit or preferred value, whether or not those ranges are separately disclosed. When a numerical range is described herein, unless otherwise stated, that range is intended to include its end values and all integers and fractions within that range.

[0046] In these examples, unless otherwise specified, the parts and percentages are by mass.

[0047] "parts by mass" refers to the basic measurement unit representing the proportional relationship of the masses of multiple components. One part can represent any unit mass. If we say that the mass part of component A is a parts and the mass part of component B is b parts, it means the ratio of the mass of component A to the mass of component B is a:b. Or, it means the mass of component A is aK and the mass of component B is bK (K is any number representing a multiple factor). It should not be misunderstood that, different from the number of mass parts, the sum of the mass parts of all components is not limited to 100 parts.

[0048] "And / or" is used to indicate that one or both of the described situations may occur. For example, A and / or B includes (A and B) and (A or B).

[0049] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "top", "bottom", etc. is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0050] To further illustrate the present invention, the present invention will be described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention. The raw materials used in the following embodiments and comparative examples of the present application can be obtained commercially unless otherwise specified, and the same raw materials are used in parallel experiments.

[0051] Preparation Example 1

[0052] A butyl rubber composite rubber compound includes 300 g of butyl rubber raw rubber, 16 g of zinc oxide, 2 g of magnesium oxide, 2 g of calcium oxide, 6 g of N-cyclohexyl-N'-phenyl-p-phenylenediamine, 18 g of paraffin wax, 150 g of carbon black, 5.625 g of sulfur, 3.75 g of accelerator TMTD, and 1.5 g of accelerator M. Its preparation method includes the following preparation steps:

[0053] Add butyl rubber raw rubber to an open mill, adjust the rotor speed to 30 r / min. After the rubber is uniformly plasticized for about 3 min, add zinc oxide, stearic acid, N-cyclohexyl-N'-phenyl-p-phenylenediamine, and paraffin wax and mix for 3 min. Subsequently, add carbon black in two portions and mix for 3 min until the carbon black is uniformly dispersed. Finally, add sulfur, accelerator TMTD, and accelerator M and mix for 3 min. Adjust the roll gap to thin the rubber sheet, and take off the sheet after 7 min to obtain the butyl rubber composite rubber compound.

[0054] Preparation Example 2

[0055] A butyl rubber composite rubber compound includes 300 g of butyl rubber raw rubber, 16 g of zinc oxide, 2 g of magnesium oxide, 2 g of calcium oxide, 6 g of N-cyclohexyl-N'-phenyl-p-phenylenediamine, 18 g of paraffin wax, 165 g of carbon black, 5.625 g of sulfur, 3.75 g of accelerator TMTD, and 1.5 g of accelerator M. Its preparation method includes the following preparation steps:

[0056] Add raw butyl rubber on an open mill, adjust the rotor speed to 30 r / min. After the rubber is evenly plasticized for about 3 min, add zinc oxide, stearic acid, N-cyclohexyl-N'-phenyl-p-phenylenediamine, and paraffin wax and mix for 3 min. Then add carbon black in two portions and mix for 3 min until the carbon black is evenly dispersed. Finally, add sulfur, accelerator TMTD, and accelerator M and mix for 3 min. Adjust the roll gap to thin the rubber sheet, and take off the sheet after 7 min to obtain a butyl rubber composite masterbatch.

[0057] Preparation Example 3

[0058] A butyl rubber composite masterbatch, comprising 300 g of raw butyl rubber, 16 g of zinc oxide, 2 g of magnesium oxide, 2 g of calcium oxide, 6 g of N-cyclohexyl-N'-phenyl-p-phenylenediamine, 18 g of paraffin wax, 180 g of carbon black, 5.625 g of sulfur, 3.75 g of accelerator TMTD, and 1.5 g of accelerator M. Its preparation method includes the following preparation steps:

[0059] Add raw butyl rubber on an open mill, adjust the rotor speed to 30 r / min. After the rubber is evenly plasticized for about 3 min, add zinc oxide, stearic acid, N-cyclohexyl-N'-phenyl-p-phenylenediamine, and paraffin wax and mix for 3 min. Then add carbon black in two portions and mix for 3 min until the carbon black is evenly dispersed. Finally, add sulfur, accelerator TMTD, and accelerator M and mix for 3 min. Adjust the roll gap to thin the rubber sheet, and take off the sheet after 7 min to obtain a butyl rubber composite masterbatch.

[0060] Comparative Preparation Example 1

[0061] A butyl rubber composite masterbatch, comprising 300 g of raw butyl rubber, 16 g of zinc oxide, 2 g of magnesium oxide, 2 g of calcium oxide, 6 g of N-cyclohexyl-N'-phenyl-p-phenylenediamine, 18 g of paraffin wax, 120 g of carbon black, 5.625 g of sulfur, 3.75 g of accelerator TMTD, and 1.5 g of accelerator M. Its preparation method includes the following preparation steps:

[0062] Add raw butyl rubber on an open mill, adjust the rotor speed to 30 r / min. After the rubber is evenly plasticized for about 3 min, add zinc oxide, stearic acid, N-cyclohexyl-N'-phenyl-p-phenylenediamine, and paraffin wax and mix for 3 min. Then add carbon black in two portions and mix for 3 min until the carbon black is evenly dispersed. Finally, add sulfur, accelerator TMTD, and accelerator M and mix for 3 min. Adjust the roll gap to thin the rubber sheet, and take off the sheet after 7 min to obtain a butyl rubber composite masterbatch.

[0063] Comparative Preparation Example 2

[0064] A butyl rubber composite mixing gum, comprising 300 g of butyl rubber raw gum, 16 g of zinc oxide, 2 g of magnesium oxide, 2 g of calcium oxide, 6 g of N-cyclohexyl-N'-phenyl-p-phenylenediamine, 18 g of paraffin wax, 135 g of carbon black, 5.625 g of sulfur, 3.75 g of accelerator TMTD and 1.5 g of accelerator M. Its preparation method includes the following preparation steps:

[0065] Add the butyl rubber raw gum on an open mill, adjust the rotor speed to 30 r / min. After the rubber is evenly plasticized for about 3 min, add zinc oxide, stearic acid, N-cyclohexyl-N'-phenyl-p-phenylenediamine, and paraffin wax and mix for 3 min. Then add carbon black in two portions and mix for 3 min until the carbon black is evenly dispersed. Finally, add sulfur, accelerator TMTD, and accelerator M and mix for 3 min. Adjust the roll gap to thin the rubber sheet, and take off the sheet after 7 min to obtain the butyl rubber composite mixing gum.

[0066] Comparative Preparation Example 3

[0067] A butyl rubber composite mixing gum, comprising 300 g of butyl rubber raw gum, 20 g of zinc oxide, 3 g of magnesium oxide, 3 g of calcium oxide, 6 g of N-cyclohexyl-N'-phenyl-p-phenylenediamine, 8 g of paraffin wax, 180 g of carbon black, 2.5 g of sulfur, 2 g of accelerator TMTD and 1.5 g of accelerator M. Its preparation method includes the following preparation steps:

[0068] Add the butyl rubber raw gum on an open mill, adjust the rotor speed to 30 r / min. After the rubber is evenly plasticized for about 3 min, add zinc oxide, stearic acid, N-cyclohexyl-N'-phenyl-p-phenylenediamine, and paraffin wax and mix for 3 min. Then add carbon black in two portions and mix for 3 min until the carbon black is evenly dispersed. Finally, add sulfur, accelerator TMTD, and accelerator M and mix for 3 min. Adjust the roll gap to thin the rubber sheet, and take off the sheet after 7 min to obtain the butyl rubber composite mixing gum.

[0069] Comparative Preparation Example 4

[0070] A butyl rubber composite mixing gum, comprising 300 g of butyl rubber raw gum, 20 g of stearic acid, 6 g of N-cyclohexyl-N'-phenyl-p-phenylenediamine, 18 g of paraffin wax, 180 g of carbon black, 5.625 g of sulfur, 3.75 g of accelerator TMTD and 1.5 g of accelerator M. Its preparation method includes the following preparation steps:

[0071] Add raw butyl rubber on the open mill, adjust the rotor speed to 30 r / min. After about 3 minutes when the rubber is evenly plasticized, add zinc oxide, stearic acid, N-cyclohexyl-N'-phenyl-p-phenylenediamine, and paraffin and mix for 3 minutes. Then add carbon black in two portions and mix for 3 minutes until the carbon black is evenly dispersed. Finally, add sulfur, accelerator TMTD, and accelerator M and mix for 3 minutes. Adjust the roll gap to thin out the rubber sheet, and take off the sheet after 7 minutes to obtain the butyl rubber composite masterbatch.

[0072] Example 1

[0073] A preparation method of a novel semi-conductive buffer layer for cables, comprising the following steps:

[0074] (1) Cut the butyl rubber composite masterbatch of Preparation Example 3 into rubber particles, then put them into a beaker, add solvent naphtha No. 120. The rubber particles account for 14 wt% of the total mass of the system. Place the beaker on a magnetic stirrer, set the rotation speed to 800 r / min, stir for 6 h, observe the dissolution situation, and then put it into a water bath heating pot and heat and stir for 6 h. The water bath heating temperature is 50 °C to obtain a rubber solution;

[0075] (2) Lay a semi-conductive water-resistant tape with a thickness of 0.3 mm flat on an automatic coater, pour in the rubber solution, adjust the coating thickness to 0.05 mm, automatically coat the rubber solution at a lower rate, and then put the made semi-conductive buffer layer into an oven at 80 °C and dry for 10 min. Then put it into an oven at 170 °C and vulcanize for 10 min to form a rubber coating and obtain the buffer layer.

[0076] Example 2

[0077] A preparation method of a novel semi-conductive buffer layer for cables, comprising the following steps:

[0078] (1) Cut the butyl rubber composite masterbatch of Preparation Example 3 into rubber particles, then put them into a beaker, add solvent naphtha No. 120. The rubber particles account for 14 wt% of the total mass of the system. Place the beaker on a magnetic stirrer, set the rotation speed to 800 r / min, stir for 6 h, observe the dissolution situation, and then put it into a water bath heating pot and heat and stir for 6 h. The water bath heating temperature is 50 °C to obtain a rubber solution;

[0079] (2) Lay a semi-conductive nylon tape with a thickness of 0.114 mm flat on an automatic coater, pour in the rubber solution, adjust the coating thickness to 0.05 mm, automatically coat the rubber solution at a lower rate, and then put the made semi-conductive buffer layer into an oven at 80 °C and dry for 10 min. Then put it into an oven at 170 °C and vulcanize for 10 min to form a rubber coating and obtain the buffer layer.

[0080] Comparative Example 1

[0081] A preparation method of a novel semi-conductive buffer layer for cables, comprising the following steps:

[0082] (1) Cut the butyl rubber composite masterbatch of Preparation Example 3 into rubber particles, then put them into a beaker, add No. 120 solvent naphtha. The rubber particles account for 14 wt% of the total mass of the system. Place the beaker on a magnetic stirrer, set the rotation speed to 800 r / min, stir for 6 h, observe the dissolution situation, and then put it into a water bath heating pot for heating and stirring for 6 h. The water bath heating temperature is 50 °C to obtain a rubber solution;

[0083] (2) Lay a semi-conductive non-woven fabric with a thickness of 0.31 mm flat on an automatic coater, pour the rubber solution, adjust the coating thickness to 0.05 mm, automatically coat the rubber solution at a lower rate, and then put the made semi-conductive buffer layer into an oven at 80 °C for drying for 10 min, and then put it into an oven at 170 °C for vulcanization for 10 min to form a rubber coating and obtain the buffer layer.

[0084] Comparative Example 2

[0085] A cable semi-conductive buffer layer, the buffer layer is a semi-conductive non-woven fabric tape with a thickness of 0.31 mm.

[0086] Comparative Example 3

[0087] A cable semi-conductive buffer layer, the buffer layer is a semi-conductive water-resistant tape with a thickness of 0.3 mm.

[0088] Comparative Example 4

[0089] A cable semi-conductive buffer layer, the buffer layer is a semi-conductive nylon tape with a thickness of 0.114 mm.

[0090] Comparative Example 5

[0091] A preparation method of a novel semi-conductive buffer layer for cables, comprising the following steps:

[0092] (1) Cut the butyl rubber composite masterbatch of Comparative Preparation Example 3 into rubber particles, then put them into a beaker, add No. 120 solvent naphtha. The rubber particles account for 14 wt% of the total mass of the system. Place the beaker on a magnetic stirrer, set the rotation speed to 800 r / min, stir for 6 h, observe the dissolution situation, and then put it into a water bath heating pot for heating and stirring for 6 h. The water bath heating temperature is 50 °C to obtain a rubber solution;

[0093] (2) Lay the semiconductive resistive water tape with a thickness of 0.3 mm flat on the automatic coater, pour in the rubber solution, adjust the coating thickness to 0.05 mm, automatically coat the rubber solution at a lower rate, and then put the made semiconductive buffer layer into an oven at 80 °C to dry for 10 min, and then put it into an oven at 170 °C to vulcanize for 10 min to form a rubber coating and obtain the buffer layer.

[0094] Comparative Example 6

[0095] A preparation method of a novel semiconductive buffer layer for cables includes the following steps:

[0096] (1) Cut the butyl rubber composite masterbatch of Comparative Preparation Example 4 into rubber particles, then put them into a beaker, add No. 120 solvent naphtha, the rubber particles account for 14 wt% of the total mass fraction of the system, place the beaker on a magnetic stirrer, set the rotation speed to 800 r / min, stir for 6 h, observe the dissolution situation, and then put it into a water bath heating pot to heat and stir for 6 h, and the water bath heating temperature is 50 °C to obtain a rubber solution;

[0097] (2) Lay the semiconductive resistive water tape with a thickness of 0.3 mm flat on the automatic coater, pour in the rubber solution, adjust the coating thickness to 0.05 mm, automatically coat the rubber solution at a lower rate, and then put the made semiconductive buffer layer into an oven at 80 °C to dry for 10 min, and then put it into an oven at 170 °C to vulcanize for 10 min to form a rubber coating and obtain the buffer layer.

[0098] Comparative Example 7

[0099] A preparation method of a novel semiconductive buffer layer for cables includes the following steps:

[0100] (1) Cut the butyl rubber composite masterbatch of Comparative Preparation Example 2 into rubber particles, then put them into a beaker, add No. 120 solvent naphtha, the rubber particles account for 14 wt% of the total mass fraction of the system, place the beaker on a magnetic stirrer, set the rotation speed to 800 r / min, stir for 6 h, observe the dissolution situation, and then put it into a water bath heating pot to heat and stir for 6 h, and the water bath heating temperature is 50 °C to obtain a rubber solution;

[0101] (2) Lay the semiconductive resistive water tape with a thickness of 0.3 mm flat on the automatic coater, pour in the rubber solution, adjust the coating thickness to 0.05 mm, automatically coat the rubber solution at a lower rate, and then put the made semiconductive buffer layer into an oven at 80 °C to dry for 10 min, and then put it into an oven at 170 °C to vulcanize for 10 min to form a rubber coating and obtain the buffer layer.

[0102] Performance detection test

[0103] 1. The butyl rubber composite masterbatches prepared in Preparation Examples 1-3 and Comparative Preparation Examples 1-2 above were respectively placed in a 70°C flat vulcanizer and melted for 30 min, and then cross-linked and compression-molded in a 15 MPa, 170°C flat vulcanizer for 10 min to obtain rubber sheets with a thickness of 1 mm. The rubber sheets were cut into specimens of 5 cm * 11 cm, and the volume resistivity at a temperature of 25-100°C was measured using a semi-conductive rubber and plastic resistance tester according to the national standard GB-3048.3-2007. The test results are as Figure 1 shown.

[0104] 2. The cross-section of the butyl rubber composite masterbatch prepared in Preparation Example 3 above was observed using a scanning electron microscope. The SEM images obtained are as Figures 2-3 shown, and it can be found that the carbon black component is evenly distributed and the dispersibility of the filler in the material is good.

[0105] 3. The volume resistivity and surface resistance of the semi-conductive buffer layers prepared in Examples 1-2 and Comparative Examples 1-7 above were measured. The volume resistivity of the buffer layer is required to be below 1*10 5 Ω·cm, and the surface resistance is required to be below 1000 Ω. The test standard is T / CEEIA 610—2022 "Semi-conductive Tape for Buffer Layers of Power Cables with Rated Voltage of 110 kV and Above". The test results are shown in Table 1 below.

[0106] 4. The maximum breaking force and elongation at break of the semi-conductive buffer layers prepared in Examples 1-2 and Comparative Examples 1-7 above were measured. The test standard is T / CEEIA 610—2022 "Semi-conductive Tape for Buffer Layers of Power Cables with Rated Voltage of 110 kV and Above". The test results are shown in Table 1 below. Table 1 - Performance Test Results of Semi-conductive Buffer Layers Prepared in Examples and Comparative Examples of This Application

[0107]

[0108] As Figure 1 and shown in Table 1, by vulcanizing the butyl rubber composites of Preparation Examples 1-3 and Comparative Preparation Examples 1-2 into rubber sheets, it can be found that the volume resistivity is between 10-90 Ω·cm, the volume resistivity is relatively small, and as the carbon black content increases, the volume resistivity gradually decreases. The volume resistivity of the rubber sheet prepared in Preparation Example 3 has been reduced to near the threshold and has good electrical conductivity, while the volume resistivity of the rubber sheet prepared in Comparative Preparation Example 1-2 of the comparative example is relatively high, and coating it on the surface of the semi-conductive buffer tape is likely to affect the overall volume resistivity of the buffer layer, resulting in a relatively high volume resistivity of the buffer layer and a decrease in the mechanical strength of the buffer layer.

[0109] As shown in Table 1, in Example 1, a semiconductive resistance water tape was used as the base material and a rubber coating was applied on the surface. In Example 2, a semiconductive nylon tape was used as the base material and a rubber coating was applied on the surface. The volume resistivity of the prepared buffer layer was lower than 1×10 5 Ω·cm, and the surface resistance was lower than 1000 Ω, having a good effect of homogenizing the field strength of the conductive ability; while in Comparative Example 1, a semiconductive non-woven fabric was used as the base material and a rubber coating was applied on the surface. The volume resistivity of the prepared buffer layer was higher than 1.5×10 5 Ω·cm, and the surface resistance was higher than 3000 Ω, with poor conductivity and unable to meet the requirements of higher electrical performance, indicating that using a semiconductive resistance water tape and a semiconductive nylon tape is more suitable as the base material of the cable buffer layer.

[0110] As shown in Table 1, the buffer layers of Comparative Examples 2-4 used semiconductive non-woven fabrics, semiconductive resistance water tapes, and semiconductive nylon tapes without rubber coatings. Compared with Examples 1-2 and Comparative Example 1, the buffer layers of Comparative Examples 2-4 had lower tensile strength, indicating that after coating with the butyl rubber composite coating, the tensile properties of the cable buffer layer were significantly improved, and the buffer layer prepared with the semiconductive nylon tape had significantly better tensile properties, indicating that the semiconductive nylon tape is more suitable as the basic tape material of the cable buffer tape. In addition, the volume resistivity and surface resistance of the semiconductive resistance water tape in Comparative Example 3 were higher than those of Example 1 without rubber coating.

[0111] As shown in Table 1, in Preparation Example 3 of the present application, zinc oxide, magnesium oxide, and calcium oxide reacted with hydrogen sulfide generated by sulfur vulcanization during the vulcanization of butyl rubber, avoiding the destruction of disulfide bonds in the rubber by hydrogen sulfide. After the rubber solution was vulcanized, a rubber coating was formed on the semiconductive buffer tape material, which could improve the overall mechanical strength of the buffer layer. In Comparative Preparation Example 1, due to too little zinc oxide, magnesium oxide, and calcium oxide and too much sulfur added, many disulfide bonds in the rubber coating formed after vulcanization were damaged by hydrogen sulfide, resulting in a significant decrease in the overall mechanical strength of the buffer layer.

[0112] The specific embodiments described above further detailed the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only specific embodiments of the present invention and is not used to limit the protection scope of the present invention. It is particularly pointed out that for those skilled in the art, any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A new type of cable semiconductive buffer layer, characterized in that: The invention comprises a semi-conductive buffer tape and a rubber coating on the surface of the semi-conductive buffer tape, wherein the semi-conductive buffer tape is a semi-conductive water-resistant tape or a semi-conductive nylon tape, and the rubber coating comprises the following components in parts by weight: Butyl rubber: 300 parts; Conductive filler: 150-180 parts; Functional additives: 13-30 parts; Paraffin: 15-20 parts; Vulcanizing agent: 4-7 parts; The functional additives include zinc oxide, magnesium oxide and calcium oxide in a mass ratio of 4:(0.5-1):(0.5-1).

2. The novel cable semiconductive buffer layer as claimed in claim 1, characterized in that: The rubber coating further comprises 3-9 parts by weight of an antioxidant; And / or, the rubber coating further comprises 1-6 parts by weight of a vulcanization accelerator.

3. The novel cable semiconductive buffer layer as claimed in claim 2, characterized in that: The vulcanization accelerator includes 2-4 parts by weight of accelerator TMTD and 1-2 parts by weight of accelerator M.

4. The novel cable semiconductive buffer layer as claimed in claim 1, characterized in that: The functional additives include zinc oxide, magnesium oxide and calcium oxide in a mass ratio of 4:0.5:0.

5.

5. The novel cable semiconductive buffer layer as claimed in claim 1, characterized in that: The conductive filler is at least one of carbon black, carbon nanotubes, graphene, graphite, and nano-metal elements.

6. The novel cable semiconductive buffer layer as claimed in claim 2, characterized in that: The antioxidant is N-cyclohexyl-N'-phenyl-p-phenylenediamine; And / or, the vulcanizing agent is sulfur.

7. The novel cable semiconductive buffer layer as claimed in claim 1, characterized in that: The thickness of the semi-conductive buffer tape is 0.1-1 mm.

8. A method for preparing a novel cable semiconductive buffer layer as claimed in any one of claims 1 to 7, characterized in that: The following steps are involved: (1) Cutting the butyl rubber composite material compound into rubber particles, adding No. 120 solvent oil, stirring for 4-10 hours, and then heating and stirring in a water bath for 4-8 hours to obtain a rubber solution; (2) A rubber solution is coated on the surface of the substrate, dried and vulcanized to form a rubber coating to obtain a buffer layer.

9. The method for preparing the novel cable semiconductive buffer layer according to claim 8, characterized in that: In step (1), the preparation method of the butyl rubber composite material mixed rubber is as follows: butyl rubber is added to an open mill, and after plasticizing evenly, functional additives, antioxidants, and paraffin are added and mixed evenly, then carbon black is added in several times, and after mixing evenly, vulcanizers and vulcanization accelerators are added and mixed evenly, and the roller distance is adjusted to thin the rubber sheet, and the butyl rubber composite material mixed rubber is obtained.

10. The method for preparing the novel cable semiconductive buffer layer according to claim 8, characterized in that: In step (1), the mass ratio of the rubber material to No. 120 solvent oil is (10-20): (80-90); and / or, in step (1), the water bath heating temperature is 40-60° C.; and / or, in step (2), the coating thickness of the rubber solution is 0.02-0.08 mm; and / or, in step (2), the drying temperature is 60-100° C. and the drying time is 5-15 min; And / or, in step (2), the vulcanization temperature is 150-180° C. and the vulcanization time is 5-15 min.

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