Cable encapsulating material and preparation method and application thereof

Abstract

The invention discloses a cable potting material as well as a preparation method and application thereof, and relates to the technical field of potting adhesives. According to the cable encapsulating material provided by the invention, the hydroxyl silicone oil capable of forming a silicon-oxygen dynamic bond is adopted as a base material, meanwhile, a specific substance is compounded as a water absorbing material, the base material can be softened at the initial stage of meeting water and is convenient to overhaul, and after the base material is placed for a period of time, water in the material can be automatically cured again after being fixed by the water absorbing material; and even if the environment humidity is still high, the obtained material still has excellent hardness due to the fact that the moisture is rapidly fixed. Therefore, the cable encapsulating material provided by the invention not only can maintain a good reversible curing effect, but also can stably exist in a humid environment.

Description

Technical Field

[0001] The present invention relates to the technical field of potting adhesives, and in particular to a cable potting material and a preparation method and application thereof. Background Art

[0002] Cables play a vital role in power transmission. During cable laying, cable joints are key components for achieving complete connections between wire segments. To prevent electrical conduction between cable joints and prevent failure due to moisture, they are typically sealed with an insulating potting compound.

[0003] However, existing cable potting materials usually use epoxy resin or silicone as a matrix, which easily absorbs water and moisture in a humid environment, resulting in moisture accumulation inside the cable and accelerated insulation aging. At the same time, the cable potting glue with epoxy resin and silicone as a matrix has an irreversible curing process, which requires mechanical cutting and removal during cable maintenance, damaging the cable and pipeline and increasing maintenance costs. Introducing reversibly cross-linked dynamic bonds into the potting glue material is beneficial for maintenance. However, the dynamic bonds are easily hydrolyzed under humid conditions, causing the potting glue to soften, which greatly reduces the safety of cable operation. Based on the above two reasons, existing cable potting glue is usually prone to deterioration and failure in the humid climate in southern my country, and its service life is greatly reduced. For this reason, there is an urgent need to provide a cable potting material that can stably exist in a humid environment and still has a good reversible curing effect. Summary of the Invention

[0004] To address the shortcomings of the prior art, the present invention provides a cable potting material that utilizes a hydroxyl silicone oil capable of forming dynamic silicon-oxygen bonds as a base material and is compounded with a specific substance as a water-absorbing material. The base material softens upon initial contact with water, facilitating maintenance. After a period of storage, the moisture within the material is fixed by the water-absorbing material, allowing the material to resolidify. Furthermore, even in high humidity environments, the rapid fixation of moisture allows the resulting material to maintain excellent hardness. Therefore, the cable potting material provided by the present invention maintains a good reversible curing effect while remaining stable in humid environments.

[0005] Another object of the present invention is to provide a method for preparing a cable potting material.

[0006] Another object of the present invention is to provide an application of a cable potting material.

[0007] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0008] A cable potting material, comprising the following raw materials in parts by weight:

[0009] 5-15 parts of water-absorbing material, 10-20 parts of base material, 65-85 parts of thermal conductive filler;

[0010] The water-absorbing material comprises a water-absorbing resin, bentonite and a molecular sieve in a mass ratio of (3-8): (2-5): (1-2), wherein the moisture absorption rate of the water-absorbing resin is ≥20 g / (g min), and the pore size of the molecular sieve is 0.1-1 nm;

[0011] The matrix material includes an organic silicone resin, and the organic silicone resin includes hydroxy silicone oil.

[0012] The cable potting material provided by the present invention adopts hydroxy silicone oil as the matrix material, and dynamic silicon-oxygen bonds can be formed between the molecular chains of the hydroxy silicone oil. When encountering liquid water, reversible fracture of the dynamic bonds and softening of the material can occur at specific parts, which is conducive to maintenance. After maintenance, timely drying can make the maintenance parts re-solidify. However, after re-solidification, the cable potting material may still need to face high humidity conditions. In this regard, the inventors of this application have found through a large number of experimental studies that when three water-absorbing substances, water-absorbing resin, bentonite and molecular sieve, are added to the system of the present invention at the same time, the resulting cable potting material can not only maintain the excellent reversible curing characteristics brought by the dynamic silicon-oxygen bonds, which is convenient for maintenance, but also can achieve rapid and sufficient absorption of moisture in the air through different mechanisms. When facing external humid conditions, the concentration of moisture absorbed in the matrix material can be reduced. The material softens only when encountering liquid water, and is therefore suitable for use in high humidity environments. Based on this, the potting material in the present invention only softens when it encounters liquid water. After the liquid water evaporates to form water vapor, the moisture inside the potting material can be quickly absorbed and fixed by the water-absorbing material, and the dynamic bonds provided by the matrix material are reformed and can re-solidify by itself, avoiding the performance degradation and shortened service life caused by the introduction of dynamic bonds.

[0013] It should be noted that the thermally conductive filler is incorporated into the present invention to ensure a good thermal conductivity path is formed within the potting material. This allows moisture absorbed into the potting material to evaporate and drain rapidly along the thermal conductivity path, ensuring that the cable potting material provided by the present invention can quickly achieve a balanced water absorption and desorption in humid environments, maintaining the rate of water absorption and evaporation. Without a thermally conductive filler, not only would the potting material's thermal conductivity be reduced, but the moisture absorbed into the absorbent material would not be able to be drained promptly, leading to excessive accumulation, which could easily lead to the breakage of dynamic bonds in the base material and softening and failure of the potting material.

[0014] In the cable potting material provided by the present invention, the water-absorbing material needs to be compounded with a water-absorbing resin with a moisture absorption rate of ≥20g / (gmin) and bentonite and a molecular sieve with a pore size of 0.1 to 1nm, wherein the water-absorbing resin can quickly absorb moisture in the air, and the moisture absorbed by the water-absorbing resin can then migrate to the bentonite and the molecular sieve with a specific pore size through capillary phenomena and other effects. Therefore, the compounding of the three substances can greatly increase the water absorption capacity and water absorption rate. At the same time, the porous structure of the molecular sieve and bentonite increases the specific surface area in contact with the thermal conductive filler, making it easy to transfer the absorbed moisture to the thermal conductive path, thereby achieving discharge. The water-absorbing resin has an insufficient moisture absorption rate and cannot quickly absorb moisture from the air, resulting in excessive water absorption by the matrix in a humid environment, and the cable potting material is prone to softening and failure. The inappropriate pore size of the molecular sieve also causes the material to soften easily.

[0015] Preferably, the water-absorbing resin includes at least one of sodium polyacrylate and polyacrylamide.

[0016] More preferably, the moisture absorption rate of the water-absorbing resin is 20 to 30 g / (g min).

[0017] More preferably, the moisture absorption rate of the sodium polyacrylate is 20 to 25 g / (g min).

[0018] More preferably, the moisture absorption rate of the polyacrylamide is 25 to 30 g / (g min).

[0019] It should be noted that the test method for the moisture absorption rate of the water-absorbing resin in the present invention comprises the following steps:

[0020] After drying the water-absorbing resin, measure the mass of the dried sample using an electronic balance. Place the dried sample in a beaker and add sufficient deionized water to allow the resin to absorb water until it is completely swollen. Then, filter the sample under normal pressure. After filtration, measure the mass again using an electronic balance. Calculate the sample's water absorption rate based on the difference in mass before and after water absorption.

[0021] More preferably, the molecular weight Mw of the water-absorbing resin is 1,000,000 to 4,000,000 g / mol.

[0022] More preferably, the molecular weight Mw of the sodium polyacrylate is 1,000,000 to 3,000,000 g / mol.

[0023] More preferably, the molecular weight Mw of the polyacrylamide is 2,000,000 to 4,000,000 g / mol.

[0024] Preferably, the bentonite includes at least one of sodium-based bentonite and calcium-based bentonite.

[0025] Preferably, the bentonite has a particle size range of 20 to 100 μm.

[0026] Preferably, the pore size of the molecular sieve is 0.2 to 0.5 nm.

[0027] Preferably, the molecular sieve includes at least one of 3A molecular sieve and 4A molecular sieve.

[0028] Preferably, the hydroxy silicone oil is modified with borate.

[0029] The borate modification of the hydroxy silicone oil-based material containing silicon-oxygen dynamic bonds can introduce additional borate dynamic bonds, further increase the speed of the material's water absorption and softening, and help improve the re-curing effect.

[0030] More preferably, the method for modifying hydroxy silicone oil with borate comprises the following steps:

[0031] S1. Take hydroxy silicone oil and trimethyl borate in a mass ratio of (5 to 15): 1 and add them to the reactor;

[0032] S2 was added to the reactor 0.5% by mass of hydroxy silicone oil dibutyltin dilaurate as a catalyst, through nitrogen protection;

[0033] S3. Raise the temperature to 80-90°C, stir and react at a speed of 300-500 rpm for 2-3 hours, and obtain borate-modified hydroxy silicone oil after the reaction is completed.

[0034] More preferably, the molecular weight of the hydroxy silicone oil is 4000-6000 g / mol.

[0035] Preferably, the thermally conductive filler includes at least one of aluminum nitride, aluminum oxide, and graphene.

[0036] More preferably, the particle size D50 of the aluminum oxide is ≤ 10 μm.

[0037] More preferably, the raw materials for preparing the alumina include coarse alumina particles, medium alumina particles and fine alumina particles, the particle size range of the coarse alumina particles is 40-50 μm, the particle size range of the medium alumina particles is 10-20 μm, and the particle size range of the fine alumina particles is 1-5 μm.

[0038] More preferably, the alumina comprises the following preparation raw materials in parts by mass:

[0039] 2 parts of coarse alumina particles, 1 to 4 parts of medium alumina particles, and 4 to 7 parts of fine alumina particles.

[0040] By compounding thermally conductive fillers of different particle sizes, more thermal conductive pathways can be created in the system, which is beneficial for the evaporation of water absorbed by the water-absorbing material, and further beneficial for the overall potting material to quickly reach a water absorption-drainage balance.

[0041] More preferably, the graphene has a lateral size of 5 to 20 μm and a thickness of 0.5 to 2 nm.

[0042] More preferably, the graphene is modified, and the modification is performed using a silane coupling agent.

[0043] More preferably, the aluminum nitride has a D50 particle size of 2 to 15 μm, a D10 particle size of 0.5 to 5 μm, and a D90 particle size of 15 to 30 μm.

[0044] More preferably, the thermally conductive filler comprises the following components in parts by mass:

[0045] 60-90 parts of aluminum oxide and / or aluminum nitride, 0.5-5 parts of graphene.

[0046] In a specific embodiment of the present invention, the "60 to 90 parts of aluminum oxide and / or aluminum nitride" means that when the thermal conductive filler contains only aluminum oxide or aluminum nitride, the added amount is 60 to 90 parts, and when the thermal conductive filler contains both aluminum oxide and aluminum nitride, the total added amount is 60 to 90 parts.

[0047] Preferably, the raw materials for preparing the cable potting material further include 2 to 5 parts of auxiliary agents, and the auxiliary agents include at least one of flame retardants, dispersants, leveling agents, and defoaming agents.

[0048] More preferably, the auxiliary agent includes the following components in parts by mass:

[0049] 2 to 4 parts flame retardant, 1 to 2 parts dispersant, 0 to 1 part leveling agent, 0 to 1 part defoaming agent.

[0050] More preferably, the flame retardant includes at least one of magnesium hydroxide, aluminum hydroxide, and aluminum hypophosphite.

[0051] More preferably, the dispersant includes a silane coupling agent.

[0052] More preferably, the silane coupling agent includes at least one of γ-methacryloxypropyltrimethoxysilane and γ-glycidoxypropyltrimethoxysilane.

[0053] More preferably, the leveling agent comprises polyether-modified silicone.

[0054] The present invention also protects a method for preparing the above-mentioned cable potting material, comprising the following steps:

[0055] Mix all the raw materials in proportion to obtain the product.

[0056] Preferably, when the raw materials for preparing the cable potting material include alumina, the step of preparing alumina is further included before mixing the raw materials in proportion. The preparing alumina includes: mixing the raw materials for preparing alumina in proportion, and ball milling to obtain alumina.

[0057] On the basis of compounding particles of different particle sizes, further ball milling is beneficial to improving the filling degree and compactness between particles and reducing the porosity.

[0058] More preferably, the ball milling speed is 200-500 rpm, and the time is ≤2h.

[0059] The above ball milling conditions are conducive to obtaining alumina with D50≤10μm.

[0060] More preferably, after the aluminum oxide is prepared, the method further comprises the step of modifying the aluminum oxide with a silane coupling agent, wherein the silane coupling agent comprises γ-methacryloxypropyltrimethoxysilane.

[0061] Preferably, the mixing of the raw materials in proportion comprises: mixing the water-absorbing material, the base material and the auxiliary agent at a temperature of 30-100° C. and a rotation speed of 600-1000 rpm, then adding the remaining raw materials and increasing the rotation speed to 1000-1400 rpm, and mixing to obtain the product.

[0062] Preferably, after mixing the raw materials in proportion, the method further comprises a degassing step, wherein the degassing is performed under a vacuum degree of ≤0.15 MPa.

[0063] The present invention also protects the application of the cable potting material in cables.

[0064] Preferably, the application conditions of the cable include: air humidity ≥ 80%.

[0065] Preferably, the potting thickness of the potting material in the cable is 5 to 20 mm.

[0066] Compared with the prior art, the present invention has the following beneficial effects:

[0067] The cable potting material provided by the present invention has excellent reversible maintenance performance and can be softened when exposed to liquid water. After maintenance, timely drying can make the repaired part re-solidify, and the hardness after re-solidification is no more than 10 Shore A hardness difference from the initial hardness, which is conducive to the maintenance of specific parts; at the same time, the water-absorbing material inside the potting material of the present invention can quickly absorb and fix water vapor, so the material will not be triggered to soften by water vapor. Its hardness retention rate can reach more than 60% after being placed in a high-humidity application environment for 12 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1This is a schematic diagram of the cable potting material obtained in Example 1 of the present invention softening when exposed to water.

[0069] Figure 2 This is a schematic diagram of the cable potting material obtained in Example 1 of the present invention after self-solidification. DETAILED DESCRIPTION

[0070] The present invention will be further described below in conjunction with specific embodiments, but the examples do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the examples of the present invention are conventionally purchased raw materials and reagents. Among them, the raw material information used in each example and comparative example is as follows:

[0071] Sodium polyacrylate: water absorption rate is 22 g / (g min), molecular weight Mw is 2000000 g / mol.

[0072] Polyacrylamide: water absorption rate is 27 g / (g min), molecular weight Mw is 3000000 g / mol.

[0073] Sodium carboxymethyl cellulose: water absorption rate is 16 g / (g·min), molecular weight Mw is 250,000 g / mol.

[0074] Sodium bentonite: particle size is 50μm.

[0075] Calcium-based bentonite: particle size is 50μm.

[0076] Hydroxy silicone oil-1: commercially available, molecular weight 5000 g / mol.

[0077] Hydroxy silicone oil-2: a product obtained by borate modification of hydroxy silicone oil-1, wherein the borate modification comprises the following steps:

[0078] S1. Take hydroxy silicone oil-1 and trimethyl borate in a mass ratio of 10:1 and add them to the reactor;

[0079] S2 was added to the reactor hydroxy silicone oil -1 mass 0.5% dibutyltin dilaurate as a catalyst, through nitrogen protection;

[0080] S3. Raise the temperature to 80-90°C and stir the mixture at a speed of 300-500 rpm for 2-3 hours. After the reaction, borate-modified hydroxy silicone oil is obtained, which is represented by hydroxy silicone oil-2.

[0081] Polydimethylsiloxane: commercially available, molecular weight 5000 g / mol.

[0082] Graphene: 10 μm in lateral dimension and 1 nm in thickness; modified with a silane coupling agent before use, including the following steps:

[0083] Graphene and silane coupling agent KH-560 were added to ethanol in a mass ratio of 1:1 to prepare a 10 wt% suspension, and ultrasonically treated for 30 minutes (power 300 W, frequency 40 kHz), and solid-liquid separation was performed to obtain the product.

[0084] Polyether modified siloxane: leveling agent BYK-333.

[0085] γ-Methacryloyloxypropyltrimethoxysilane: silane coupling agent KH570.

[0086] γ-Glycidyloxypropyltrimethoxysilane: Silane coupling agent KH560.

[0087] 3A molecular sieve: commercially available, pore size

[0088] 4A molecular sieve: commercially available, pore size

[0089] 13X molecular sieve: commercially available, pore size

[0090] MCM-41 molecular sieve: commercially available, pore size 3-5 nm.

[0091] Example 1

[0092] A cable potting material, comprising the following raw materials in parts by weight:

[0093] 9 parts of water-absorbing material, 15 parts of hydroxy silicone oil-1, 71.5 parts of thermal conductive filler, 5 parts of additives;

[0094] The water-absorbing material comprises a water-absorbing resin sodium polyacrylate, sodium bentonite and 4A molecular sieve in a mass ratio of 5:3:1;

[0095] The thermal conductive filler includes alumina and graphene in a mass ratio of 70:1.5. The raw materials for preparing the alumina include fine particles, medium particles and coarse particles in a mass ratio of 5:3:2. The particle size of the coarse particles ranges from 40 to 50 μm, the particle size of the medium particles ranges from 10 to 20 μm, and the particle size of the fine particles ranges from 1 to 5 μm.

[0096] The auxiliary agent includes magnesium hydroxide, gamma-glycidyloxypropyltrimethoxysilane and a leveling agent in a mass ratio of 3:1.5:0.5.

[0097] The preparation method of the cable potting material in this embodiment includes the following steps:

[0098] The raw materials for preparing alumina (coarse particles, medium particles, and fine particles) are mixed in proportion, placed in a ball mill, and milled for 2 hours using zirconium oxide balls as the grinding medium (ball-to-material ratio of 3:1) to obtain alumina with D50 ≤ 10 μm; hydroxy silicone oil-1, water-absorbing material, and additives are added to a high-speed stirring kettle in sequence, the temperature is raised to 60°C, and stirred at 800 rpm for 30 minutes. Subsequently, the remaining raw materials are added, the speed is increased to 1200 rpm, and the mixture is mixed for 1 hour. The mixture is degassed under a vacuum degree of 0.08 MPa for 15 minutes to obtain the cable potting material.

[0099] Example 2

[0100] A cable potting material, comprising the following raw materials in parts by weight:

[0101] 11.5 parts of water-absorbing material, 18 parts of hydroxy silicone oil-1, 82 parts of thermal conductive filler, 5.5 parts of additives;

[0102] The water-absorbing material comprises a water-absorbing resin sodium polyacrylate, calcium-based bentonite and 3A molecular sieve in a mass ratio of 6:4:1.5;

[0103] The thermal conductive filler includes alumina and graphene in a mass ratio of 80:2. The raw materials for preparing the alumina include fine particles, medium particles and coarse particles in a mass ratio of 6:2:2. The particle size of the coarse particles ranges from 40 to 50 μm, the particle size of the medium particles ranges from 10 to 20 μm, and the particle size of the fine particles ranges from 1 to 5 μm.

[0104] The auxiliary agent includes aluminum hydroxide, gamma-methacryloxypropyltrimethoxysilane and a leveling agent in a mass ratio of 4:1:0.5.

[0105] The preparation method of the cable potting material in this embodiment is basically the same as that in Example 1.

[0106] Example 3

[0107] A cable potting material, comprising the following raw materials in parts by weight:

[0108] 12 parts of water-absorbing material, 20 parts of hydroxy silicone oil-2, 78 parts of thermal conductive filler, 6 parts of additives;

[0109] The water-absorbing material comprises water-absorbing resin polyacrylamide, calcium-based bentonite and 3A molecular sieve in a mass ratio of 7:3:2;

[0110] The thermal conductive filler includes aluminum nitride, aluminum oxide, and graphene in a mass ratio of 65:10:3, the particle size D50 of the aluminum nitride is 10 μm, and the raw materials for preparing the aluminum oxide include fine particles, medium particles, and coarse particles in a mass ratio of 6:2:2. The particle size of the coarse particles ranges from 40 to 50 μm, the particle size of the medium particles ranges from 10 to 20 μm, and the particle size of the fine particles ranges from 1 to 5 μm.

[0111] The auxiliary agent includes aluminum hypophosphite and gamma-methacryloxypropyltrimethoxysilane in a mass ratio of 5:1.

[0112] The preparation method of the cable potting material in this embodiment is basically the same as that in Example 1.

[0113] Example 4

[0114] A cable potting material, which differs from Example 1 only in that:

[0115] The 4A molecular sieve was replaced with an equal mass of 13X molecular sieve.

[0116] The preparation method of the cable potting material in this embodiment is basically the same as that in Example 1.

[0117] Example 5

[0118] A cable potting material, which differs from Example 1 only in that:

[0119] Replace hydroxy silicone oil-1 with an equal mass of hydroxy silicone oil-2.

[0120] The preparation method of the cable potting material in this embodiment is basically the same as that in Example 1.

[0121] Example 6

[0122] A cable potting material, which differs from Example 1 only in that:

[0123] In the preparation method of the cable potting material in this embodiment, the raw materials for preparing alumina (coarse particles, medium particles, and fine particles) are mixed in proportion and then ball milling is not performed.

[0124] Example 7

[0125] A cable potting material, which differs from Example 1 only in that:

[0126] The raw materials for preparing alumina only include fine particles and medium particles with a mass ratio of 5:3.

[0127] The preparation method of the cable potting material in this embodiment is basically the same as that in Example 1.

[0128] Example 8

[0129] A cable potting material, which differs from Example 1 only in that:

[0130] The raw materials for preparing alumina only include fine particles and coarse particles with a mass ratio of 5:2.

[0131] The preparation method of the cable potting material in this embodiment is basically the same as that in Example 1.

[0132] Example 9

[0133] A cable potting material, which differs from Example 1 only in that:

[0134] The raw materials for preparing alumina only include medium particles and coarse particles with a mass ratio of 3:2.

[0135] The preparation method of the cable potting material in this embodiment is basically the same as that in Example 1.

[0136] Example 10

[0137] A cable potting material, which differs from Example 1 only in that:

[0138] The raw materials for preparing alumina include fine particles, medium particles and coarse particles in a mass ratio of 5:0.5:5.

[0139] The preparation method of the cable potting material in this embodiment is basically the same as that in Example 1.

[0140] Example 11

[0141] A cable potting material, which differs from Example 1 only in that:

[0142] The raw materials for preparing alumina include fine particles, medium particles and coarse particles in a mass ratio of 5:6:1.

[0143] The preparation method of the cable potting material in this embodiment is basically the same as that in Example 1.

[0144] Example 12

[0145] A cable potting material, which differs from Example 1 only in that:

[0146] The particle size of the coarse alumina particles ranges from 50 to 60 μm, the particle size of the medium particles ranges from 5 to 10 μm, and the particle size of the fine particles ranges from 0.5 to 2 μm.

[0147] The preparation method of the cable potting material in this embodiment is basically the same as that in Example 1.

[0148] Example 13

[0149] A cable potting material, which differs from Example 1 only in that:

[0150] The particle size of the coarse alumina particles ranges from 30 to 40 μm, the particle size of the medium particles ranges from 20 to 30 μm, and the particle size of the fine particles ranges from 5 to 10 μm.

[0151] The preparation method of the cable potting material in this embodiment is basically the same as that in Example 1.

[0152] Example 14

[0153] A cable potting material, which differs from Example 1 only in that:

[0154] The water-absorbing material comprises water-absorbing resin sodium polyacrylate, sodium bentonite and 4A molecular sieve in a mass ratio of 3:5:2.

[0155] The preparation method of the cable potting material in this embodiment is basically the same as that in Example 1.

[0156] Example 15

[0157] A cable potting material, which differs from Example 1 only in that:

[0158] The water-absorbing material comprises water-absorbing resin sodium polyacrylate, sodium bentonite and 4A molecular sieve in a mass ratio of 8:2:1.

[0159] The preparation method of the cable potting material in this embodiment is basically the same as that in Example 1.

[0160] Example 16

[0161] A cable potting material, which differs from Example 1 only in that:

[0162] The water-absorbing material comprises water-absorbing resin sodium polyacrylate, sodium bentonite and 4A molecular sieve in a mass ratio of 6:4:1.5.

[0163] The preparation method of the cable potting material in this embodiment is basically the same as that in Example 1.

[0164] Comparative Example 1

[0165] A cable potting material, which differs from Example 1 only in that:

[0166] The 4A molecular sieve was replaced with an equal mass of MCM-41 molecular sieve.

[0167] The preparation method of the cable potting material in this comparative example is basically the same as that in Example 1.

[0168] Comparative Example 2

[0169] A cable potting material, which differs from Example 1 only in that:

[0170] The water-absorbing material comprises water-absorbing resin sodium polyacrylate, sodium bentonite and 4A molecular sieve in a mass ratio of 10:1:0.5.

[0171] The preparation method of the cable potting material in this comparative example is basically the same as that in Example 1.

[0172] Comparative Example 3

[0173] A cable potting material, which differs from Example 1 only in that:

[0174] The water-absorbing material comprises water-absorbing resin sodium polyacrylate, sodium bentonite and 4A molecular sieve in a mass ratio of 2:6:3.

[0175] The preparation method of the cable potting material in this comparative example is basically the same as that in Example 1.

[0176] Comparative Example 4

[0177] A cable potting material, which differs from Example 1 only in that:

[0178] The preparation comprises the following raw materials in parts by weight:

[0179] 4 parts of water-absorbing material, 25 parts of hydroxy silicone oil-1, 90 parts of thermal conductive filler, and 5 parts of additives.

[0180] The preparation method of the cable potting material in this comparative example is basically the same as that in Example 1.

[0181] Comparative Example 5

[0182] A cable potting material, which differs from Example 1 only in that:

[0183] The preparation comprises the following raw materials in parts by weight:

[0184] 20 parts of water-absorbing material, 5 parts of hydroxy silicone oil-1, 60 parts of thermal conductive filler, and 5 parts of additives.

[0185] The preparation method of the cable potting material in this comparative example is basically the same as that in Example 1.

[0186] Comparative Example 6

[0187] A cable potting material, which differs from Example 1 only in that:

[0188] Sodium polyacrylate was replaced with an equal mass of sodium carboxymethyl cellulose.

[0189] The preparation method of the cable potting material in this comparative example is basically the same as that in Example 1.

[0190] Comparative Example 7

[0191] A cable potting material, which differs from Example 1 only in that:

[0192] Replace hydroxy silicone oil-1 with an equal mass of polydimethylsiloxane.

[0193] The preparation method of the cable potting material in this comparative example is basically the same as that in Example 1.

[0194] Performance Testing

[0195] Initial hardness test: The cable potting materials obtained in the examples and comparative examples were placed at a temperature of 25±2°C and a relative humidity of 60±5% for 24 hours to allow them to fully cure (simulating the natural curing scenario after cable potting). The test procedure was carried out in accordance with GB / T 531.1-2008 "Test method for indentation hardness of vulcanized rubber or thermoplastic rubber", including the following steps:

[0196] 1. Cut the cured sample into test blocks with a thickness of ≥6mm and an area of ​​≥20mm×20mm. The surface should be flat and free of bubbles.

[0197] 2. Place the test block on the test platform of the hardness tester (Shore A hardness tester) with the indenter in vertical contact with the sample surface (avoid the area within 10mm of the edge);

[0198] 3. Apply pressure until the indenter is fully inserted, hold for 5 seconds, and then read the value;

[0199] 4. Select 3 different test points (spacing ≥ 5mm) on the same test block and take the average value as the initial hardness.

[0200] Reversible repair performance test: A flat area with an area of ​​2 cm × 2 cm (avoiding the edges) in the cured sample test blocks of the cable potting materials obtained in the examples and comparative examples was randomly selected for water spraying, and 0.5 mL of deionized water was evenly sprayed on the test area (simulating liquid water contact during maintenance). The hardness of the water spraying position in the cured sample was tested at the initial stage of water contact (within 5 minutes); then, the sample after water contact was placed in an 80°C oven for drying (the sample weight no longer changed within 5 minutes), and the hardness of the water spraying position after re-solidification was tested.

[0201] Hardness retention test: Place the re-cured sample after the reversible repair performance test in a constant temperature and humidity chamber with a set temperature of 25±2°C and a relative humidity of 80±2% for 720 minutes (12 hours, simulating a high humidity application environment) to test its hardness retention.

[0202] The above performance test results are shown in Table 1 and Figures 1-2 As shown:

[0203] Table 1. Performance test data of cable potting materials obtained in Examples and Comparative Examples

[0204]

[0205]

[0206] Note: The hardness mentioned in the above table is Shore A hardness.

[0207] According to the data in Table 1 above, the cable potting material provided by the present invention has excellent reversible maintenance performance. It can be softened when exposed to liquid water. After maintenance, timely drying can make the repaired part re-solidify, and the hardness after re-solidification is no more than 10 Shore A hardness difference from the initial hardness, which is conducive to the maintenance of specific parts. At the same time, the water-absorbing material inside the potting material of the present invention can quickly absorb and fix water vapor, so the material will not be triggered to soften by water vapor. Its hardness retention rate can reach more than 60% after being placed in a high humidity application environment for 12 hours.

[0208] According to the data of Examples 1 and 4, it can be seen that when the pore size of the molecular sieve is 0.2 to 0.5 nm (Example 1) as preferred in the present invention, the compounding effect of the molecular sieve with the water-absorbing resin and bentonite is better, the water absorption performance is better, and the hardness retention rate is better in a high humidity application environment.

[0209] According to the data of Examples 1 and 5, the use of borate to modify the hydroxyl silicone oil matrix material (Example 5) can achieve better application effects. This is mainly because the borate modification of the hydroxyl silicone oil matrix material containing silicon-oxygen dynamic bonds can introduce additional borate dynamic bonds, further increasing the rate of water absorption and softening of the material, and is conducive to improving the re-curing effect.

[0210] According to Examples 1 and 6, it can be seen that on the basis of compounding particles of different particle sizes, further ball milling is performed (Example 1). On the basis of controlling the ball milling conditions, alumina with D50 ≤ 10 μm can be obtained, which is beneficial to improving the filling degree and compactness between the particles, reducing the porosity, and allowing more heat conduction paths to exist in the system, which is beneficial to the evaporation of water absorbed by the water-absorbing material, and further beneficial to the overall potting material to quickly achieve water absorption-drainage balance.

[0211] By comparing Examples 1 and 7 to 9, it can be seen that when the raw materials for preparing alumina include coarse alumina particles, medium alumina particles and fine alumina particles (Example 1), the internal tightness and the number of heat conduction paths of the obtained potting material are better, which is conducive to the evaporation of water absorbed by the water-absorbing material, and is more conducive to the potting material as a whole to quickly achieve water absorption and drainage balance.

[0212] According to Examples 1, 10 to 13, the particle size range of the coarse alumina particles is 40 to 50 μm as preferred in the present invention, the particle size range of the medium alumina particles is 10 to 20 μm as preferred, and the particle size range of the fine alumina particles is 1 to 5 μm as preferred (Example 1), and the compounding effect is optimal; when the mass ratio of the three components is the preferred 2: (1 to 4): (4 to 7), the effect is also better.

[0213] According to Examples 14 to 16 and Comparative Examples 2 to 3, the proportions of the substances in the water-absorbing material are not appropriate, and the resulting potting material cannot achieve the function of rapidly absorbing and fixing moisture, and is easily softened when used in a high humidity environment.

[0214] According to Comparative Example 1, the pore size of the molecular sieve is too large, and the compounding effect of the water-absorbing material is reduced, resulting in an inability to absorb water quickly. When used in a high humidity environment, it is easy to soften.

[0215] According to Comparative Examples 4 and 5, the mass ratio of the components in the potting material is not appropriate, resulting in the inability to achieve both excellent reversible repair performance and hardness retention under high humidity.

[0216] According to Comparative Example 6, an inappropriate moisture absorption rate of the water-absorbing material may also cause the material to soften and fail when used in a high humidity environment.

[0217] According to Comparative Example 7, PDMS does not have a dynamic bond and cannot achieve reversible repair.

[0218] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A cable potting material, characterized in that: The preparation comprises the following raw materials in parts by weight: 5-15 parts of water-absorbing material, 10-20 parts of base material, 65-85 parts of thermal conductive filler; The water-absorbing material comprises a water-absorbing resin, bentonite and a molecular sieve in a mass ratio of (3-8): (2-5): (1-2), wherein the moisture absorption rate of the water-absorbing resin is ≥20 g / (g min), and the pore size of the molecular sieve is 0.1-1 nm; The matrix material includes an organic silicone resin, and the organic silicone resin includes hydroxy silicone oil.

2. The cable potting material according to claim 1, characterized in that: Include at least one of the following (a) to (g): (a) the water-absorbing resin comprises at least one of sodium polyacrylate and polyacrylamide; (b) the bentonite comprises at least one of sodium bentonite and calcium bentonite; (c) the bentonite has a particle size range of 20 to 100 μm; (d) the pore size of the molecular sieve is 0.2 to 0.5 nm; (e) the hydroxy silicone oil is modified with borate; (f) the thermally conductive filler comprises at least one of aluminum nitride, aluminum oxide, and graphene; (g) The raw materials for preparing the cable potting material further include 2 to 5 parts of an auxiliary agent, wherein the auxiliary agent includes at least one of a flame retardant, a dispersant, and a leveling agent.

3. The cable potting material according to claim 2, characterized in that: Include at least one of the following (h) to (i): (h) the particle size D50 of the aluminum oxide is ≤ 10 μm; (i) The raw materials for preparing the alumina include coarse alumina particles, medium alumina particles and fine alumina particles. The particle size of the coarse alumina particles is in the range of 40 to 50 μm, the particle size of the medium alumina particles is in the range of 10 to 20 μm, and the particle size of the fine alumina particles is in the range of 1 to 5 μm.

4. The cable potting material according to claim 3, characterized in that: The alumina comprises the following raw materials in parts by mass: 2 parts of coarse alumina particles, 1 to 4 parts of medium alumina particles, and 4 to 7 parts of fine alumina particles.

5. The cable potting material according to claim 2, characterized in that: Include at least one of the following (j) to (s): (j) the molecular weight of the hydroxy silicone oil is 4000 to 6000 g / mol; (k) the graphene has a lateral dimension of 5 to 20 μm and a thickness of 0.5 to 2 nm; (1) The graphene is subjected to a modification treatment, wherein the modification is performed using a silane coupling agent; (m) the aluminum nitride has a D50 particle size of 2 to 15 μm; (n) The thermally conductive filler comprises the following components in parts by weight: 60-90 parts of aluminum oxide and / or aluminum nitride, 0.5-5 parts of graphene; (o) The auxiliary agent comprises the following components in parts by weight: 2-4 parts flame retardant, 1-2 parts dispersant, 0-1 part leveling agent, 0-1 part defoaming agent; (p) the flame retardant comprises at least one of magnesium hydroxide, aluminum hydroxide, and aluminum hypophosphite; (q) the dispersant comprises a silane coupling agent; (r) The leveling agent includes polyether-modified silicone.

6. A method for preparing the cable potting material according to any one of claims 1 to 5, characterized in that: The steps include: Mix all the raw materials in proportion to obtain the product.

7. The preparation method according to claim 6, characterized in that: When the raw materials for preparing the cable potting material include alumina, the step of preparing alumina is further included before mixing the raw materials in proportion. The preparing alumina includes: mixing the raw materials for preparing alumina in proportion, and ball milling to obtain alumina.

8. The preparation method according to claim 6, characterized in that: Include at least one of the following (s) to (t): (s) mixing the raw materials in proportion comprises: mixing the water-absorbing material, the base material, and the auxiliary agent at a temperature of 30 to 100° C. and a rotation speed of 600 to 1000 rpm, then adding the remaining raw materials and increasing the rotation speed to 1000 to 1400 rpm, and mixing to obtain the product; (t) After the raw materials are mixed in proportion, the method further comprises a degassing step, wherein the degassing is performed under a vacuum degree of ≤0.15 MPa.

9. Use of the cable potting material according to any one of claims 1 to 5 in cables.

10. The use according to claim 9, characterized in that The application conditions of the cable include: air humidity ≥ 80%.

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