A water-blocking filling paste for cables and a method for preparing the same

Abstract

The application discloses a water-blocking filling paste for cables and a preparation method thereof, and belongs to the field of sealants. Sodium-based montmorillonite is first made into a suspension, octadecyl dimethyl benzyl ammonium chloride is added, and heating and stirring are carried out, then filtering, drying, mixing with polyether base oil, heating and dispersing, and then standing to obtain an intercalation compound, and then adding polyisobutylene and an antioxidant, stirring and mixing, and vacuum defoaming to obtain the water-blocking filling paste for cables; the quaternary ammonium salt groups are uniformly dispersed in the whole system with the montmorillonite layers, can long-acting inhibit the reproduction of molds and bacteria, inhibit the decomposition of the base oil and the additives by microorganisms, the intercalation compound structure makes the organic phase and the inorganic phase closely combined, enhances the interface bonding force and buffers the interface stress, can reduce the phase separation, agglomeration and sedimentation after cold and hot cycles, is beneficial to maintaining the uniformity of the system, and the thickening network constructed by the polyether and the polyisobutylene can reduce the base oil precipitation and volume shrinkage at high temperatures.

Description

Technical Field

[0001] This invention relates to a water-blocking filler paste for cables and its preparation method, belonging to the field of sealants. Background Technology

[0002] Water-blocking filler is a core component of power cables, primarily used to fill gaps between cable cores, conductors, and the sheath. It prevents external moisture and humidity from penetrating the cable, avoiding conductor oxidation and corrosion, and insulation breakdown due to moisture, thus ensuring the electrical safety of the cable during long-term operation. In the hot and humid regions of southern my country, there are a large number of buried and tunnel cables. These cables operate in high-temperature, high-humidity underground environments with active microbial communities. Existing water-blocking fillers exhibit significant performance shortcomings in these conditions, failing to meet the requirements for long-term stable operation.

[0003] Most existing water-blocking filler pastes use mineral oil and natural oils as base oils, combined with conventional thickeners such as soap bases and low-molecular-weight polyolefins, and also add small-molecule additives to adjust performance. These systems are rich in organic matter that can be utilized by microorganisms. The underground environment in the south has suitable temperatures for microbial reproduction, high soil moisture, and strong activity of molds, bacteria, and other microorganisms. Microorganisms can invade the interior of the paste, decompose the base oil and small-molecule additives, change the viscosity of the paste, destroy the gel structure, and ultimately cause the paste to lose its filling and supporting capacity, thus rendering the water-blocking barrier ineffective.

[0004] During cable operation, the conductor continuously heats up, with internal temperatures reaching 70-90℃. The temperature drops rapidly during nighttime shutdowns or when the air temperature decreases, creating repeated hot and cold cycles due to seasonal and diurnal temperature variations. Existing products often add inorganic water-blocking powders and mineral fillers to improve water-blocking performance. These inorganic components have significantly different coefficients of thermal expansion from the organic matrix, resulting in continuous alternating stress at the interface during temperature fluctuations. Over long-term cycling, the interface gradually peels off, the inorganic fillers agglomerate and settle, and significant phase separation occurs. The originally uniform water-blocking structure is destroyed, forming continuous seepage channels along which water vapor can quickly penetrate the conductor. Simultaneously, phase separation impairs the oil-holding capacity of the thickening network, accelerates base oil precipitation, causes overall volume shrinkage of the paste, and creates gaps between the paste and the insulation layer and sheath, further exacerbating sealing failure.

[0005] The temperature difference between hot and cold causes the antibacterial agent to peel off from the paste. After the antibacterial agent is lost, it is easier for microorganisms to multiply. The microorganisms also leave local pores at the point of reproduction, which increases thermal resistance and aggravates the local temperature difference on the cable. Summary of the Invention

[0006] In order to overcome the shortcomings of the prior art, the present invention provides a water-blocking filler paste for cables and its preparation method, which can reduce the alternating stress continuously generated at the interface between two phases during temperature alternation and effectively inhibit the reproduction of microorganisms.

[0007] The technical solution adopted by this invention to solve its technical problem is: In a first aspect, this application provides a method for preparing a water-blocking filler paste for cables, comprising the following steps: Sodium-based montmorillonite was prepared into a suspension, octadecyl dimethyl benzyl ammonium chloride was added, the mixture was heated and stirred, filtered, and dried to obtain modified montmorillonite. The polyether base oil was mixed with the modified montmorillonite, heated and dispersed, and then allowed to stand to obtain the intercalation complex. Polyisobutylene and an antioxidant were added to the intercalation composite, stirred and mixed, and then degassed under vacuum to obtain the water-blocking filler paste for cables.

[0008] Sodium-based montmorillonite has a well-developed layered structure and a large specific surface area. Sodium ions can undergo cation exchange between the layers. After octadecyl dimethyl benzyl ammonium chloride is grafted onto the montmorillonite layers through cation exchange, it will not be lost with the oil phase migration. It also has both long alkyl chains and quaternary ammonium salt groups. Quaternary ammonium salts have broad-spectrum antibacterial properties, and long alkyl chains can reduce the surface polarity of montmorillonite and improve its compatibility with the organic phase. The organic phase polyether base oil has moderate polarity, good aging resistance, and is not easily decomposed by microorganisms. It has strong interfacial forces with the modified montmorillonite. Polyisobutylene, as an auxiliary thickening component, has excellent compatibility with polyether and can further enhance the system's oil holding capacity and cohesive strength.

[0009] Further, by weight, the raw material usage is as follows: 60-75 parts of the polyether base oil, 8-15 parts of the sodium montmorillonite, 3-6 parts of the octadecyl dimethyl benzyl ammonium chloride, 10-18 parts of the polyisobutylene, and 0.3-1 part of the antioxidant.

[0010] Polyether base oil serves as a continuous oil-phase matrix, providing a continuous dispersion medium for the intercalation dispersion of montmorillonite and the uniform dispersion of various additives. This ensures moderate overall system fluidity, guaranteeing sufficient wetting and expansion of the modified montmorillonite for complete intercalation. Insufficient base oil will result in an overly viscous system, leading to incomplete dispersion of montmorillonite and localized agglomeration. Excessive base oil will result in a thin paste with insufficient oil-holding capacity. Polyisobutylene controls the paste's adhesion and sealing; excessive amounts result in excessive entanglement of the long polymer chains, leading to an overly hard paste. The proportions of each component are well-matched, maintaining long-term stability of the system's microstructure under humid and hot conditions and repeated temperature fluctuations, inhibiting multiple failure issues such as filler sedimentation, oil precipitation, and microbial decomposition.

[0011] Furthermore, the step of preparing sodium montmorillonite into a suspension includes mixing 8 to 15 parts of sodium montmorillonite with 5 to 10 parts of deionized water; the heating and stirring requirements are: heating to 60°C to 70°C and stirring for 2 to 3 hours.

[0012] When the water content is too low, it is insufficient to wet the montmorillonite particles, causing a large number of lamellar layers inside the particles to remain in an agglomerated and stacked state. This makes it difficult for subsequent cationic modifying reagents to penetrate the interlayer and complete ion exchange. Heating modification can enhance the molecular mobility of octadecyl dimethyl benzyl ammonium chloride, accelerate the migration rate of cations, and promote the rapid penetration of cations through the montmorillonite hydration layer into the interior of the lamellar layers. This replaces the original interlayer sodium ions, improves the completeness of the ion exchange reaction, and lays a preliminary foundation for the subsequent formation of intercalation complexes and the overall structural stability of the filling paste.

[0013] Furthermore, the molecular weight of the polyisobutylene is 1000~2000.

[0014] Polyisobutylene molecules with low molecular weight have a high degree of freedom of movement and are difficult to form effective entanglement and binding after penetrating into the montmorillonite intercalation network. Under long-term heating conditions, small molecule polyisobutylene is prone to slow migration and precipitation, and cannot maintain the density of the network for a long time. However, polyisobutylene molecules with high molecular weight have too long molecular chains, and the molecular steric hindrance is greatly increased, making it difficult to penetrate into the narrow gaps inside the montmorillonite intercalation structure. They can only attach to the outer surface of the intercalation skeleton.

[0015] Furthermore, before the step of adding polyisobutylene and antioxidant, 1 to 3 parts of terminal epoxy polyether are added to the intercalation composite.

[0016] Furthermore, in the step of mixing the polyether base oil with the modified montmorillonite, 0.8 to 2 parts of hydrophobic modified nanocellulose are also added.

[0017] Further, the steps for preparing the hydrophobic modified nanocellulose include: dispersing nanocellulose in an ethanol aqueous solution, adjusting the pH to 4-5, heating to 50℃-60℃, adding octadecyltrimethoxysilane dropwise, stirring and reacting for 3-4 hours, centrifuging, and drying to obtain the hydrophobic modified nanocellulose; the amount of octadecyltrimethoxysilane used is 12%-15% of the mass of the nanocellulose.

[0018] The hydrophobically modified nanocellulose obtained in this way, with appropriate grafting modification, can be stably and uniformly dispersed in the polyether base oil system and smoothly interweave with modified montmorillonite to form a composite water-blocking network. If the grafting amount is too low, the surface hydrophobic modification is insufficient, and the oleophilicity is inadequate; if the grafting amount is too high, the alkyl chains are excessively densely coated on the fiber surface, resulting in excessive steric hindrance of the fiber, making subsequent dispersion in the filler paste difficult and prone to entanglement and aggregation.

[0019] Furthermore, in the step of mixing the polyether base oil with the modified montmorillonite, the polyether base oil contains 0.2 to 0.8 parts of a benzotriazole derivative pre-dispersed.

[0020] Further, the preparation steps of the benzotriazole derivative include: preheating a terminal epoxy polyether to 80°C, adding 1-aminobenzotriazole at 6%~8% of the mass of the terminal epoxy polyether, and stirring the reaction for 2h~3h to obtain the benzotriazole derivative.

[0021] This benzotriazole derivative solves the problems of poor compatibility and easy migration / loss of traditional benzotriazole with the filler paste matrix. The amino group undergoes a ring-opening addition reaction with the epoxy group, and the benzotriazole corrosion inhibitor group is chemically grafted to the end of the polyether molecular chain. The long-chain structure of the polyether has a high compatibility with the polyether base oil inside the filler paste, and the terminal retains the active adsorption group of benzotriazole.

[0022] Furthermore, the heating and dispersion, followed by standing, steps include: heating to 80°C~90°C, dispersing at a high speed of 3000r / min~4000r / min for 30min~45min, and then keeping warm and standing for 2h~3h.

[0023] This process is used to control the uniformity of intercalation, avoid insufficient intercalation or excessive peeling of the sheets. Heating can improve the activity of polyether molecular chains, reduce the overall viscosity of the polyether system, weaken the intermolecular entanglement resistance, and make it easier for polyether molecules to complete intercalation. High-strength shear force can break up the modified montmorillonite agglomerates, creating contact conditions for polyether intercalation. Subsequent static setting completes the deep intercalation arrangement.

[0024] Furthermore, the requirements for stirring, mixing, and vacuum degassing are as follows: heat to 105℃~120℃, stir at 300r / min~500r / min for 1.5h~2h, then control the vacuum degree at -0.08MPa~-0.095MPa, and perform vacuum degassing for 20min~30min.

[0025] If the mixing temperature is too low, the system viscosity will be too high, hindering the diffusion of macromolecules and causing localized agglomeration of polyisobutylene, which may lead to uneven local aging resistance. If the temperature is too high, the risk of thermal degradation of organic components increases, and premature chain breakage of polymers may occur, impairing the stability of the paste. Low-speed stirring can achieve uniform mixing of components while avoiding excessive shear force tearing the already formed montmorillonite intercalation network, thus preventing the ordered intercalation structure from being sheared and destroyed.

[0026] Secondly, this application provides a water-blocking filler paste for cables, which is made by the method for preparing water-blocking filler paste for cables described in the first aspect, and has a longer service life and better environmental adaptability compared to traditional mineral oil-based filler pastes.

[0027] The beneficial effects of this invention are as follows: In the water-blocking filler paste for cables of this invention, the montmorillonite sheets extend the water vapor penetration path and improve the density of the water-blocking barrier. The quaternary ammonium salt groups are uniformly dispersed throughout the system along with the montmorillonite sheets, which can effectively inhibit the growth of mold and bacteria, inhibit the decomposition of base oil and additives by microorganisms, and prevent the viscosity of the paste from being changed by microorganisms. The intercalated composite structure makes the organic phase and inorganic phase tightly combined, enhances the interfacial bonding force and buffers the interfacial stress. After cold and hot cycling, it can reduce phase separation agglomeration and sedimentation, which is conducive to maintaining the uniformity of the system. The thickening network jointly constructed by polyether and polyisobutylene can reduce the precipitation and volume shrinkage of base oil at high temperatures. Overall, it can meet the long-term operation requirements of cables in the humid and hot southern regions. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure are described clearly and completely below. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this invention.

[0029] It should be understood that, without conflict, any and all embodiments of the present invention can be combined with technical features of any other embodiment or multiple other embodiments to obtain other embodiments. The present invention includes such combinations to obtain other embodiments.

[0030] In this specification, groups and their substituents may be selected by those skilled in the art to provide stable structural moieties and compounds. When a substituent is described by a conventional chemical formula written from left to right, the substituent also includes chemically equivalent substituents obtained when the structural formula is written from right to left.

[0031] Unless otherwise specified, all technical and scientific terms used herein have the standard meaning in the field to which the claimed subject matter pertains. Where multiple definitions exist for a term, the definition herein shall prevail.

[0032] This application provides a method for preparing a water-blocking filler paste for cables, comprising the following steps: S1: Sodium-based montmorillonite is made into a suspension, octadecyl dimethyl benzyl ammonium chloride is added, heated and stirred, filtered and dried to obtain modified montmorillonite.

[0033] S2: Mix polyether base oil with modified montmorillonite, heat to disperse, and then let stand to obtain intercalation complex.

[0034] S3: Add polyisobutylene and antioxidant to the intercalation compound, stir and mix, and degas under vacuum to obtain a water-blocking filler paste for cables.

[0035] The antibacterial functional groups grafted onto the surface of layered silicates can be uniformly dispersed throughout the system, inhibiting microbial growth and preventing the decomposition of organic matter. The intercalated composite structure allows silicate sheets to form molecular-level interactions with polyether molecules, significantly reducing the difference in thermal expansion at the two-phase interface. During thermal cycling, it can buffer interfacial stress, prevent phase separation and filler sedimentation, and maintain system homogeneity. At the same time, the layered structure of layered silicates can extend the water vapor permeation path and improve the compactness of the water barrier; the intercalated structure can also improve oil retention capacity and reduce base oil seepage at high temperatures. Overall, it improves the service life under humid and hot environments from both structural stability and functional protection perspectives.

[0036] The raw materials, by weight, include 60-75 parts polyether base oil, 8-15 parts sodium montmorillonite, 3-6 parts octadecyl dimethyl benzyl ammonium chloride, 10-18 parts polyisobutylene (molecular weight 1000-2000), 0.3-1 parts antioxidant, 5-10 parts deionized water, and 10-15 parts anhydrous ethanol.

[0037] Step S1 is as follows: Sodium-based montmorillonite is mixed with deionized water and stirred to form a uniform suspension. The temperature is raised to 60-70°C, and octadecyl dimethyl benzyl ammonium chloride is slowly added. The mixture is kept warm and stirred for 2-3 hours. After completion, the mixture is filtered, the filter cake is washed three times with anhydrous ethanol, dried, and then ground through a 200-mesh sieve to obtain organically modified montmorillonite.

[0038] Step S2 is as follows: Add polyether base oil to the reactor, heat to 80~90℃, add modified montmorillonite, disperse at high speed of 3000~4000r / min for 30~45min, then keep warm and stand for 2~3h to allow polyether molecules to fully insert into the montmorillonite layers.

[0039] Step S3 is as follows: add polyisobutylene and antioxidant to the reactor, heat to 110~120℃, stir at a low speed of 300~500r / min for 1.5~2h; then control the vacuum degree to -0.08~-0.095MPa, degas under vacuum for 20~30min, and cool to room temperature to obtain the finished product.

[0040] High-speed dispersion combined with heat preservation and static setting allows polyether molecules to fully diffuse into the montmorillonite interlayer, achieving molecular-level intercalation and significantly enhancing the interfacial bonding between the two phases. High-temperature blending ensures the complete dissolution and dispersion of polyisobutylene, which, together with the intercalation structure, constructs a composite thickening network.

[0041] If too much octadecyl dimethyl benzyl ammonium chloride is used, the grafting with montmorillonite will be incomplete, leaving residual free quaternary ammonium salts that easily migrate and precipitate at the interface, affecting the cable insulation performance. In a preferred embodiment, between steps S2 and S3, there is an additional step: adding 1 to 3 parts of terminal epoxy polyether to the intercalation composite, maintaining the system temperature at 80 to 90°C, and stirring at 500 r / min for 40 to 60 min.

[0042] End-epoxy polyethers can undergo ring-opening reactions with free amine molecules, firmly binding them to the polyether chain segments, preventing the small molecules from migrating to the interface, maintaining the stability of the surface resistivity of the insulation layer, and ensuring the electrical safety of the cable.

[0043] The performance degradation rate of the paste near the cable conductor is significantly faster than in other areas. This is because, during long-term operation, there is a possibility of copper ions from the cable precipitating and diffusing into the paste. Copper ions catalyze the oxidative degradation of the base oil and thickening components, leading to gel network breakage, paste softening, and oil separation. In a preferred embodiment, 0.2 to 0.8 parts of a benzotriazole derivative as a passivating agent are pre-dispersed in the polyether base oil of step S2, which can eliminate the catalytic aging effect of copper ions on organic components. It exhibits good compatibility with the system, does not affect the original antibacterial, water-blocking, and oil-holding properties, and can significantly reduce the aging rate of the conductor contact area, extend the overall service life of the paste, and improve its long-term compatibility with copper conductors.

[0044] Benzotriazole is highly polar. In order to make it evenly dispersed in base oil, 1-aminobenzotriazole can be added to a preheated terminal epoxy polyether at 80°C at 6% to 8% of the mass of the terminal epoxy polyether, and the mixture can be stirred and kept at this temperature for 2 to 3 hours to obtain the benzotriazole derivative.

[0045] Benzotriazole derivatives are covalently linked to the epoxy groups of terminal epoxy polyethers via amino groups, rather than being directly dispersed in the system. The polyether segments of the terminal epoxy polyethers are similar to and compatible with the polyether base oil, thus avoiding the free migration of passivating agents.

[0046] In a preferred embodiment, step S2 also involves adding 0.8 to 2 parts of hydrophobic modified nanocellulose.

[0047] Hydrophobic nanocellulose and montmorillonite sheets form a dense, interlocking barrier network, significantly extending the permeation path of gaseous water vapor and reducing its permeation rate. Simultaneously, nanocellulose physically strengthens the gel network structure, enhancing oil retention at high temperatures, further delaying the degradation of antibacterial group properties, and overall improving the long-term stability of the ointment in high-humidity environments.

[0048] The steps for preparing hydrophobically modified nanocellulose can be as follows: dispersing nanocellulose in an aqueous ethanol solution, adjusting the pH to 4-5, heating to 50℃-60℃, adding octadecyltrimethoxysilane dropwise, stirring and reacting for 3-4 hours, centrifuging, and drying to obtain hydrophobically modified nanocellulose; the amount of octadecyltrimethoxysilane used is 12%-15% of the mass of nanocellulose.

[0049] The modification introduces long alkylsiloxane chains, which can hydrophobically associate and physically entangle with the alkyl chains of polyisobutylene and polyether base oil in the system; the residual active hydroxyl groups on the surface of the modified cellulose can form hydrogen bonds with the quaternary ammonium salt on the surface of montmorillonite, and can even react with the epoxy groups of terminal epoxy polyethers to form covalent bonds, thus achieving multi-point anchoring with the original components.

[0050] Example 1 Raw materials (parts by weight): 68 parts polyether base oil (Dow UCON OSP-46), 11 parts sodium montmorillonite (Nanocor PGN), 4.5 parts octadecyl dimethyl benzyl ammonium chloride, 14 parts polyisobutylene (Dallin PB1300), 0.6 parts antioxidant (BASF Irganox L101), and 7 parts deionized water.

[0051] Sodium montmorillonite was passed through a 100-mesh coarse sieve to remove large particulate impurities; polyether base oil was preheated to 60°C for later use.

[0052] Sodium-based montmorillonite and deionized water were added to a mixing tank and stirred at 800 rpm for 30 minutes at room temperature to prepare a homogeneous suspension. The suspension was heated to 65°C, and octadecyl dimethyl benzyl ammonium chloride was slowly and uniformly added over a period of 30 minutes. After addition, the mixture was kept at this temperature and stirred for 2.5 hours. Heating was then stopped, and the mixture was allowed to cool naturally to 40°C. The mixture was then filtered under pressure, and the filter cake was collected. The filter cake was then transferred to anhydrous ethanol and soaked and stirred for 15 minutes before being filtered again under pressure. This process of washing was repeated three times. After washing, the filter cake was first drained under normal pressure, then dried in an 80°C vacuum oven to constant weight. After drying, the cake was pulverized using a grinder and passed through a 200-mesh standard sieve to obtain modified montmorillonite.

[0053] Add the preheated polyether base oil to the reactor, heat it to 85°C, add the modified montmorillonite in one go, and disperse it at 3500 r / min for 40 min. After dispersion, maintain the temperature and let it stand for 2.5 h to complete the intercalation.

[0054] Polyisobutylene and antioxidant were added to the reactor, and the temperature was raised to 120°C. The mixture was stirred at a low speed of 400 r / min for 1.8 h to ensure that the components were fully mixed. The material temperature was maintained, and the vacuum degree of the system was controlled at -0.09 MPa. The mixture was stirred at a low speed of 100 r / min for 25 min to remove air bubbles. After degassing, the mixture was slowly cooled to room temperature to obtain the water-blocking filler paste for cables of Example 1.

[0055] Example 2 Raw materials (parts by weight): 60 parts polyether base oil (Dow UCON OSP-46), 9 parts sodium montmorillonite (Nanocor PGN), 8 parts octadecyl dimethyl benzyl ammonium chloride, 16 parts polyisobutylene (Dailin PB1300), 0.5 parts antioxidant (BASF Irganox L101), and 8 parts deionized water.

[0056] Sodium montmorillonite was passed through a 100-mesh coarse sieve to remove large particulate impurities; polyether base oil was preheated to 60°C for later use.

[0057] Sodium-based montmorillonite and deionized water were added to a mixing tank and stirred at 800 rpm for 30 minutes at room temperature to prepare a homogeneous suspension. The suspension was heated to 70°C, and octadecyl dimethyl benzyl ammonium chloride was slowly and uniformly added over a period of 30 minutes. After addition, the mixture was kept at this temperature and stirred for 2 hours. Heating was then stopped, and the mixture was allowed to cool naturally to 40°C. The mixture was then filtered under pressure, and the filter cake was collected. The filter cake was then transferred to anhydrous ethanol and soaked and stirred for 15 minutes before being filtered again under pressure. This process of washing was repeated three times. After washing, the filter cake was first drained under normal pressure, then dried in an 80°C vacuum oven to constant weight. After drying, the cake was pulverized using a grinder and passed through a 200-mesh standard sieve to obtain modified montmorillonite.

[0058] Add the preheated polyether base oil to the reactor, heat it to 80°C, add the modified montmorillonite in one go, and disperse it at a high speed of 3000 r / min for 45 min. After dispersion, maintain the temperature and let it stand for 3 h to complete the intercalation.

[0059] Polyisobutylene and antioxidant were added to the reactor, and the temperature was raised to 110°C. The mixture was stirred at a low speed of 400 r / min for 1.5 h to ensure that the components were fully mixed. The material temperature was maintained, and the vacuum degree of the system was controlled at -0.09 MPa. The mixture was stirred at a low speed of 100 r / min for 30 min to remove air bubbles. After degassing, the mixture was slowly cooled to room temperature to obtain the water-blocking filler paste for cables of Example 2.

[0060] Example 3 Raw materials (parts by weight): 70 parts polyether base oil (Dow UCON OSP-46), 15 parts sodium montmorillonite (Nanocor PGN), 6 parts octadecyl dimethyl benzyl ammonium chloride, 15 parts polyisobutylene (Dalin PB1300), 0.4 parts antioxidant (BASF Irganox L101), 2 parts epoxy-terminated polyether (R-EPO-PEG-EPO-2k from Ruixi Biotechnology), and 9 parts deionized water.

[0061] Sodium montmorillonite was passed through a 100-mesh coarse sieve to remove large particulate impurities; polyether base oil was preheated to 60°C for later use.

[0062] Sodium-based montmorillonite and deionized water were added to a mixing tank and stirred at 800 rpm for 30 minutes at room temperature to prepare a homogeneous suspension. The suspension was heated to 60°C, and octadecyl dimethyl benzyl ammonium chloride was slowly and uniformly added over a period of 30 minutes. After addition, the mixture was kept at this temperature and stirred for 2.5 hours. Heating was then stopped, and the mixture was allowed to cool naturally to 40°C. The mixture was then filtered under pressure, and the filter cake was collected. The filter cake was then transferred to anhydrous ethanol and soaked and stirred for 15 minutes before being filtered again under pressure. This process of washing was repeated three times. After washing, the filter cake was first drained under normal pressure, then dried in an 80°C vacuum oven to constant weight. After drying, the cake was pulverized using a grinder and passed through a 200-mesh standard sieve to obtain modified montmorillonite.

[0063] Preheated polyether base oil was added to the reactor and heated to 85°C. Modified montmorillonite was added in one go and dispersed at 4000 r / min for 30 min. After dispersion, the temperature was maintained and the mixture was kept at this temperature for 2.5 h to complete the intercalation and obtain the intercalation composite.

[0064] Add terminal epoxy polyether to the intercalation composite, maintain the system temperature at 85℃, and stir at 500 r / min for 40~60 min.

[0065] Polyisobutylene and antioxidant were added to the reactor, and the temperature was raised to 105°C. The mixture was stirred at a low speed of 400 r / min for 1.5 h to ensure that the components were fully mixed. The material temperature was maintained, and the vacuum degree of the system was controlled at -0.08 MPa. The mixture was stirred at a low speed of 100 r / min for 20 min to remove air bubbles. After degassing, the mixture was slowly cooled to room temperature to obtain the water-blocking filler paste for cables of Example 3.

[0066] Example 4 Raw materials (parts by weight): 60 parts polyether base oil (Dow UCON OSP-46), 8 parts sodium montmorillonite (Nanocor PGN), 3 parts octadecyl dimethyl benzyl ammonium chloride, 10 parts polyisobutylene (Dalin PB1300), 0.3 parts antioxidant (BASF Irganox L101), 5 parts deionized water, and 1 part hydrophobically modified nanocellulose.

[0067] The preparation steps of hydrophobic modified nanocellulose are as follows: Nanocellulose (Wuhan Kemike Biomedical Technology Co., Ltd.) is dispersed in an 80% (v / v) aqueous ethanol solution to prepare a 3% (w / w) suspension; the pH is adjusted to 4.5 with glacial acetic acid, the temperature is raised to 55℃, and octadecyltrimethoxysilane is slowly added dropwise, with the amount being 15% of the mass of nanocellulose; the reaction is carried out with stirring for 4 hours, and after centrifugation, it is washed three times with anhydrous ethanol, dried under vacuum at 60℃, and ground to obtain hydrophobic modified nanocellulose.

[0068] Sodium montmorillonite was passed through a 100-mesh coarse sieve to remove large particulate impurities; polyether base oil was preheated to 60°C for later use.

[0069] Sodium-based montmorillonite and deionized water were added to a mixing tank and stirred at 800 rpm for 30 minutes at room temperature to prepare a homogeneous suspension. The suspension was heated to 65°C, and octadecyl dimethyl benzyl ammonium chloride was slowly and uniformly added over a period of 30 minutes. After addition, the mixture was kept at this temperature and stirred for 2.5 hours. Heating was then stopped, and the mixture was allowed to cool naturally to 40°C. The mixture was then filtered under pressure, and the filter cake was collected. The filter cake was then transferred to anhydrous ethanol and soaked and stirred for 15 minutes before being filtered again under pressure. This process of washing was repeated three times. After washing, the filter cake was first drained under normal pressure, then dried in an 80°C vacuum oven to constant weight. After drying, the cake was pulverized using a grinder and passed through a 200-mesh standard sieve to obtain modified montmorillonite.

[0070] Add the preheated polyether base oil to the reactor, heat it to 85°C, add the modified montmorillonite and hydrophobic modified nanocellulose at once, and disperse it at 4000 r / min for 40 min. After dispersion, maintain the temperature and let it stand for 2.5 h to complete the intercalation.

[0071] Polyisobutylene and antioxidant were added to the reactor, and the temperature was raised to 105°C. The mixture was stirred at a low speed of 500 r / min for 1.5 h to ensure that the components were fully mixed. The material temperature was maintained, and the vacuum degree of the system was controlled at -0.09 MPa. The mixture was stirred at a low speed of 100 r / min for 25 min to remove air bubbles. After degassing, the mixture was slowly cooled to room temperature to obtain the water-blocking filler paste for cables of Example 4.

[0072] Example 5 Raw materials (parts by weight): 72 parts polyether base oil (Dow UCON OSP-46), 14 parts sodium montmorillonite (Nanocor PGN), 5 parts octadecyl dimethyl benzyl ammonium chloride, 15 parts polyisobutylene (Dallin PB1300), 0.6 parts antioxidant (BASF Irganox L101), 0.8 parts 1-aminobenzotriazole, and 7 parts deionized water.

[0073] Sodium montmorillonite was passed through a 100-mesh coarse sieve to remove large particulate impurities; polyether base oil was preheated to 60°C, 1-aminobenzotriazole was added, and the mixture was stirred for 10 minutes until homogeneous and ready for use.

[0074] Sodium-based montmorillonite and deionized water were added to a mixing tank and stirred at 800 rpm for 30 minutes at room temperature to prepare a homogeneous suspension. The suspension was heated to 65°C, and octadecyl dimethyl benzyl ammonium chloride was slowly and uniformly added over a period of 30 minutes. After addition, the mixture was kept at this temperature and stirred for 2.5 hours. Heating was then stopped, and the mixture was allowed to cool naturally to 40°C. The mixture was then filtered under pressure, and the filter cake was collected. The filter cake was then transferred to anhydrous ethanol and soaked and stirred for 15 minutes before being filtered again under pressure. This process of washing was repeated three times. After washing, the filter cake was first drained under normal pressure, then dried in an 80°C vacuum oven to constant weight. After drying, the cake was pulverized using a grinder and passed through a 200-mesh standard sieve to obtain modified montmorillonite.

[0075] Add the preheated polyether base oil to the reactor, heat it to 85°C, add the modified montmorillonite in one go, and disperse it at a high speed of 3000 r / min for 40 min. After dispersion, maintain the temperature and let it stand for 3 h to complete the intercalation.

[0076] Polyisobutylene and antioxidant were added to the reactor, and the temperature was raised to 115°C. The mixture was stirred at a low speed of 400 r / min for 1.8 h to ensure thorough mixing of the components. The material temperature was maintained, and the vacuum degree of the system was controlled at -0.09 MPa. The mixture was stirred at a low speed of 100 r / min for 25 min to remove air bubbles. After degassing, the mixture was slowly cooled to room temperature to obtain the water-blocking filler paste for cables of Example 5.

[0077] Example 6 Raw materials (parts by weight): 72 parts polyether base oil (Dow UCON OSP-46), 18 parts sodium montmorillonite (Nanocor PGN), 5 parts octadecyl dimethyl benzyl ammonium chloride, 15 parts polyisobutylene (Dallin PB1300), 0.6 parts antioxidant (BASF Irganox L101), 0.5 parts benzotriazole derivative, and 5 parts deionized water.

[0078] The preparation steps of the benzotriazole derivative are as follows: preheat the terminal epoxy polyether to 80°C, add 1-aminobenzotriazole at 8% of the mass of the terminal epoxy polyether, keep warm and stir for 2 hours to obtain the benzotriazole derivative.

[0079] Sodium montmorillonite was passed through a 100-mesh coarse sieve to remove large particulate impurities; polyether base oil was preheated to 60°C, benzotriazole derivative was added, and the mixture was stirred for 10 minutes until homogeneous and ready for use.

[0080] Sodium-based montmorillonite and deionized water were added to a mixing tank and stirred at 800 rpm for 30 minutes at room temperature to prepare a homogeneous suspension. The suspension was heated to 65°C, and octadecyl dimethyl benzyl ammonium chloride was slowly and uniformly added over a period of 30 minutes. After addition, the mixture was kept at this temperature and stirred for 2.5 hours. Heating was then stopped, and the mixture was allowed to cool naturally to 40°C. The mixture was then filtered under pressure, and the filter cake was collected. The filter cake was then transferred to anhydrous ethanol and soaked and stirred for 15 minutes before being filtered again under pressure. This process of washing was repeated three times. After washing, the filter cake was first drained under normal pressure, then dried in an 80°C vacuum oven to constant weight. After drying, the cake was pulverized using a grinder and passed through a 200-mesh standard sieve to obtain modified montmorillonite.

[0081] Add the preheated polyether base oil to the reactor, heat it to 85°C, add the modified montmorillonite in one go, and disperse it at 3800 r / min for 40 min. After dispersion, maintain the temperature and let it stand for 3 h to complete the intercalation.

[0082] Polyisobutylene and antioxidant were added to the reactor, and the temperature was raised to 105°C. The mixture was stirred at a low speed of 400 r / min for 1.8 h to ensure thorough mixing of the components. The material temperature was maintained, and the vacuum degree of the system was controlled at -0.09 MPa. The mixture was stirred at a low speed of 100 r / min for 20 min to remove air bubbles. After degassing, the mixture was slowly cooled to room temperature to obtain the water-blocking filler paste for cables of Example 6.

[0083] Comparative Example 1 Raw materials (parts by weight): 75 parts mineral base oil (150SN), 6 parts aluminum stearate, 8 parts superabsorbent resin (funa1122 from Funa New Materials Technology (Shanghai) Co., Ltd.), 10 parts petrolatum, and 0.5 parts antioxidant (BASF Irganox L101).

[0084] Preparation steps: Heat the base oil to 120°C, add aluminum stearate and stir until fully swollen, add petrolatum and antioxidant and stir evenly, cool to 80°C and add superabsorbent resin to disperse evenly, vacuum degas and cool before discharging.

[0085] The following tests were performed on the examples and comparative examples, and the experimental results are shown in Table 1.

[0086] Antibacterial performance: Equal amounts of sample were weighed into sterile petri dishes and evenly spread to the same thickness. 0.1 mL of a 10^5 CFU / mL Aspergillus niger spore suspension and Escherichia coli bacterial suspension were inoculated onto the sample surface. The dishes were incubated in a humid environment at 28℃ and >90% relative humidity for 72 h. After incubation, the sample surface was repeatedly rinsed with sterile physiological saline, and all eluent was collected. Viable bacteria were counted using the plate count method. A 5:1 mixture of polyether base oil and polyisobutylene was used as a blank control to calculate the antibacterial rate. Antibacterial rate = (Number of colonies in blank sample - Number of colonies in sample) / Number of colonies in blank sample × 100% Thermal cycling stability: A cycle was set from -20℃ to 90℃, with each temperature held for 8 hours, for a total of 50 cycles. The cone penetration of the sample was tested before and after the cycles, and the rate of change in cone penetration was calculated.

[0087] High-temperature oil separation rate: The oil phase was collected by the steel mesh separation method, and the sample was kept at 100℃ for 168 hours. The mass of the separated oil was calculated as the proportion of the mass of the sample to the total mass of the sample, which characterizes the high-temperature oil retention capacity of the system.

[0088] Copper-catalyzed aging performance: A copper sheet was completely embedded in the sample, ensuring full contact, and placed in a 90℃ constant temperature oven for 168 hours. The cone penetration of the sample before and after aging was measured, and the rate of change in cone penetration was calculated to reflect the degree of degradation of organic components under copper ion catalysis.

[0089] Water vapor transmission rate: Under the conditions of 38℃ and 90% relative humidity, the water vapor transmission rate per unit area within 72 hours was tested using the cup method to characterize the ability of the paste to block gaseous water vapor.

[0090] Volume resistivity: The volume resistivity of the sample was tested at 25℃ according to GB / T1692 to examine the electrical insulation safety performance of the paste.

[0091] Table 1

[0092] The analysis results show that, in Comparative Example 1, which uses a mineral oil and aluminum stearate thickening system, microorganisms can more easily decompose organic matter and destroy the gel structure, resulting in significant sedimentation and phase separation of the filler.

[0093] In Example 2, the amount of octadecyl dimethyl benzyl ammonium chloride was slightly higher, which slightly improved the antibacterial rate, but the free polar small molecules reduced the insulation performance; at the same time, the free components weakened the interfacial bonding force, and the cold and hot cycle stability and high temperature oil retention were worse than those in Example 1.

[0094] Compared with Example 1, Example 3 shows further improvement in electrical insulation performance; the enhanced interfacial bonding not only eliminates the risk of migration of free small molecules, but also strengthens the interfacial bonding between montmorillonite and the oil phase, further improving the stability and electrical safety of the system.

[0095] Example 4 introduces hydrophobically modified nanocellulose to form an interlaced barrier network with montmorillonite sheets. Compared with Example 1, the water vapor permeability is reduced, significantly improving the gaseous water vapor barrier capability; the nanocellulose also physically reinforces the gel network, further enhancing the structural stability of the system and making it better suited for service in high-humidity environments.

[0096] Example 6 uses a grafted benzotriazole derivative, with the passivating group covalently anchored to the polyether chain, resulting in better compatibility and stability. The copper-catalyzed aging inhibition effect is significantly better than that of Example 5, which uses direct addition; meanwhile, other system properties are not negatively affected, with volume resistivity, oil separation rate, and thermal cycling stability being comparable to or even slightly better than Example 1, effectively extending the service life of the paste in the conductor contact area.

[0097] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0098] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for preparing a water-blocking filler paste for cables, characterized in that, Includes the following steps: Sodium-based montmorillonite was prepared into a suspension, octadecyl dimethyl benzyl ammonium chloride was added, the mixture was heated and stirred, filtered, and dried to obtain modified montmorillonite. The polyether base oil was mixed with the modified montmorillonite, heated and dispersed, and then allowed to stand to obtain the intercalation complex. Polyisobutylene and an antioxidant were added to the intercalation composite, stirred and mixed, and then degassed under vacuum to obtain the water-blocking filler paste for cables.

2. The method for preparing the water-blocking filler paste for cables according to claim 1, characterized in that, By weight, the raw materials used are: 60-75 parts of the polyether base oil, 8-15 parts of the sodium montmorillonite, 3-6 parts of the octadecyl dimethyl benzyl ammonium chloride, 10-18 parts of the polyisobutylene, and 0.3-1 part of the antioxidant.

3. The method for preparing water-blocking filler paste for cables according to claim 2, characterized in that, The step of preparing sodium montmorillonite into a suspension includes mixing 8 to 15 parts of sodium montmorillonite with 5 to 10 parts of deionized water; the heating and stirring requirements are: heating to 60°C to 70°C and stirring for 2 to 3 hours.

4. The method for preparing water-blocking filler paste for cables according to claim 2, characterized in that, The molecular weight of the polyisobutylene is 1000~2000.

5. The method for preparing water-blocking filler paste for cables according to claim 2, characterized in that, Before adding polyisobutylene and antioxidant, 1 to 3 parts of terminal epoxy polyether are added to the intercalation composite.

6. The method for preparing water-blocking filler paste for cables according to claim 2, characterized in that, In the step of mixing the polyether base oil with the modified montmorillonite, 0.8 to 2 parts of hydrophobic modified nanocellulose are also added.

7. The method for preparing the water-blocking filler paste for cables according to claim 6, characterized in that, The steps for preparing the hydrophobic modified nanocellulose include: dispersing nanocellulose in an ethanol aqueous solution, adjusting the pH to 4-5, heating to 50℃-60℃, adding octadecyltrimethoxysilane dropwise, stirring and reacting for 3-4 hours, centrifuging, and drying to obtain the hydrophobic modified nanocellulose; the amount of octadecyltrimethoxysilane used is 12%-15% of the mass of the nanocellulose.

8. The method for preparing water-blocking filler paste for cables according to claim 2, characterized in that, In the step of mixing the polyether base oil with the modified montmorillonite, the polyether base oil contains 0.2 to 0.8 parts of a benzotriazole derivative pre-dispersed.

9. The method for preparing the water-blocking filler paste for cables according to claim 1, characterized in that, The heating and dispersion, followed by standing, steps include: heating to 80°C to 90°C, dispersing at a high speed of 3000r / min to 4000r / min for 30min to 45min, and then keeping warm and standing for 2h to 3h.

10. A water-blocking filler paste for cables, characterized in that, It is made by the method for preparing water-blocking filler paste for cables according to any one of claims 1 to 9.

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