Aging-resistant sealing glue for cable joint and preparation method thereof

Abstract

The application discloses a kind of ageing-resistant cable joint sealant and preparation method thereof, belong to sealant technical field, and the ageing-resistant cable joint sealant includes the following mass parts of raw materials: 35-50 parts of hydroxyl silicone oil, 45-60 parts of filler, 3-5 parts of fumed white carbon black, 2-5 parts of fluorine-containing hydroxyl-terminated hyperbranched polymer;3-6 parts of hydrogen-containing silicone oil, 1-5 parts of silane coupling agent, 1-3 parts of ketoxime crosslinking agent, 0.05-0.1 parts of organic tin catalyst, 0.1-0.2 parts of lubricant, 1-3 parts of carbon black;The fluorine-containing hydroxyl-terminated hyperbranched polymer is prepared by using trihydroxymethyl propane, dihydroxymethyl butyric acid and 2,2-difluoro-3-hydroxy-succinic acid as monomer.The sealant of the application has excellent comprehensive performance and ageing resistance, and still has excellent performance under high temperature and high humidity, high salt fog conditions.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sealant and specifically relates to a kind of sealant for aging-resistant cable joint and a preparation method thereof. BACKGROUND

[0002] The cable joint is a key component for connecting lines of various electrical equipment, and the cold shrink tube is a weak point of the cable intermediate joint. Due to the breathing effect of the cable intermediate joint, water and other pollutants may enter the cold shrink tube from the two ends of the cold shrink tube, causing the internal insulation strength of the joint to decrease, possibly damaging the internal electric field balance, and causing material aging and other problems. Serious problems may include electrical treeing, cable breakdown, and even cable explosion accidents.

[0003] Therefore, high quality requirements are put forward for the cold shrink tube sealant for cables. In particular, some electrical equipment is in an environment that easily causes the sealant to age for a long time, such as a high-temperature and high-humidity environment, a high-salt fog environment, and an environment with a large temperature difference between morning and evening. Poor sealing may easily lead to water and moisture intrusion, and the sealant needs to maintain good waterproofness and mechanical properties after various aging conditions in a humid environment.

[0004] Currently, the main types of sealants for cables are silicone rubber, epoxy resin, and polyurethane. Epoxy resin and polyurethane sealants generally require two components and have strict requirements for curing conditions and application processes. Furthermore, polyurethane sealants are susceptible to fungal corrosion, leading to performance degradation. Silicone rubber, due to its excellent performance, is the most widely used. CN107365503A discloses a waterproof cable sealant, which, by mass ratio, consists of 100 parts of methyl vinyl silicone rubber, 10-25 parts of fumed silica, 25-30 parts of calcium bicarbonate, 5-10 parts of rutile titanium dioxide, 1-5 parts of zinc stearate, and 5-10 parts of aniline methyltriethoxysilane. These components are mechanically stirred at 25°C for 20-30 minutes, and then 0.5-1 parts of a mixture of dibutyltin dilaurate curing agent and dibutyl phthalate are added to form the finished sealant. CN106590517A discloses a sealant, which is mainly made from the following raw materials in parts by weight: 100-200 parts of high molecular weight silicone rubber, 100-300 parts of low molecular weight silicone rubber, 200-600 parts of magnesium hydroxide, 10-100 parts of decabromodiphenyl ethane, 200-1000 parts of calcium carbonate, and 100-500 parts of talc. CN105153993A discloses an intumescent fire-retardant sealant composed of the following raw materials in parts by weight: 70-90 parts of 50000cp α,ω-dihydroxypolydimethylsiloxane, 10-30 parts of 2000cp α,ω-dihydroxypolydimethylsiloxane, 20-40 parts of activated calcium carbonate, 10-20 parts of fumed silica, 15-30 parts of ammonium polyphosphate, 3-10 parts of expanded graphite, 8-15 parts of glass fiber, 30-50 parts of micron-sized magnesium hydroxide, 3-10 parts of dimethyl silicone oil, 0.8-1.8 parts of γ-aminopropyltriethoxysilane, 1-3 parts of vinyltributylone oxime silane, 3-7 parts of methyltrimethyloxosilane, 1-3 parts of acrylic acid-methacrylate, 1-2 parts of tetrabutyl titanate, and 0.3-1 parts of dibutyltin dilaurate.

[0005] However, the existing sealants mentioned above have poor weather resistance, especially in the face of harsh environments with high temperature and humidity for extended periods. They are also susceptible to moisture erosion at high temperatures, leading to a decrease in internal insulation strength and potentially causing cable breakdowns. Therefore, there is a need to develop a sealant with superior overall performance, combining mechanical properties, waterproofing, and aging resistance. Summary of the Invention

[0006] To solve the problems in the prior art, the application provides a kind of sealing glue for aging-resistant cable joint, which is a new single-component waterproof sealing glue for cable, fully wetting when brushing on the surface of cold shrink tube and then completely curing, improving the adhesion of cold shrink tube and outer semiconductive layer, and preventing water from entering the conductor area of cable intermediate joint.At the same time, it has excellent aging resistance, excellent performance under high temperature and high humidity, high salt spray conditions, and waterproof and electrical insulation performance meeting the national grid standard.It can be used for waterproof packaging and protection of high and low voltage cable joint cold shrink tube position.

[0007] The application adopts the following technical solutions.

[0008] The first aspect of the application discloses a sealing glue for aging-resistant cable joint, comprising the following raw materials by mass fraction: 35-50 parts of hydroxyl silicone oil, 45-60 parts of filler, 3-5 parts of fumed white carbon black, 2-5 parts of fluorine-containing hydroxyl-terminated hyperbranched polymer, 3-6 parts of hydrogen-containing silicone oil, 1-5 parts of silane coupling agent, 1-3 parts of ketoxime crosslinking agent, 0.05-0.1 parts of organic tin catalyst, 0.1-0.2 parts of lubricant, and 1-3 parts of carbon black.

[0009] The fluorine-containing hydroxyl-terminated hyperbranched polymer is prepared using trihydroxymethylpropane, dihydroxymethylbutyric acid, and 2,2-difluoro-3-hydroxy-succinic acid as monomers.

[0010] Preferably, the molar ratio of trihydroxymethylpropane, dihydroxymethylbutyric acid, and 2,2-difluoro-3-hydroxy-succinic acid is 1:7-9:1-2.

[0011] Preferably, the hydroxyl silicone oil is a compound of end-hydroxyl silicone oil and side-chain hydroxyl silicone oil in a mass ratio of 6-8:1, the end-hydroxyl silicone oil has a hydroxyl content of 0.7-1.2 wt%, and the side-chain hydroxyl silicone oil has a hydroxyl content of 5-8 wt%.

[0012] Preferably, the hydrogen-containing silicone oil has an active hydrogen content of 0.5-0.7 mmol / g and a viscosity of 10000-100000 cst.

[0013] Preferably, the silane coupling agent is a compound of fluorine-containing silane coupling agent and epoxy silane coupling agent in a mass ratio of 1-2:2-5.

[0014] Preferably, the fluorine-containing silane coupling agent is at least one of tridecafluorooctyltrimethoxysilane and heptadecafluorodecyltriethoxysilane.

[0015] The epoxy silane coupling agent is at least one of 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-glycidyloxypropylmethyldimethoxysilane, 3-glycidyloxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

[0016] Preferably, the lubricant is at least one of polyethylene wax, polypropylene wax;

[0017] The filler is at least one of calcium carbonate, magnesium carbonate, dolomite, clay, talc powder, and the particle size of the filler is 1-100 μm;

[0018] The organotin catalyst is at least one of butyltin dilaurate, dioctyltin dilaurate, dibutyltin diacetate, and stannous octoate;

[0019] The ketoxime crosslinking agent is at least one of methyltributanoxysilane, vinyltributanoxysilane, phenyltributanoxysilane, and methyltetrabutanoxysilane;

[0020] The specific surface area of the fumed white carbon black is 150-180 m 2 / g.

[0021] The second aspect of the present application discloses a preparation method of a sealing glue for an aging-resistant cable joint, comprising the following steps:

[0022] Under a closed condition, the hydroxyl silicone oil and the filler are mixed uniformly in a container while being heated and degassed;

[0023] The fumed white carbon black, the fluorine-containing hydroxyl-terminated hyperbranched polymer, the hydrogen-containing silicone oil, the silane coupling agent, the ketoxime crosslinking agent, the lubricant, and the carbon black are added and mixed uniformly;

[0024] The organotin catalyst is added, vacuum is drawn, and stirring is continued to mix uniformly, and the aging-resistant cable cold shrink tube sealing glue is obtained by machine extrusion.

[0025] Preferably, the fluorine-containing hydroxyl-terminated hyperbranched polymer is prepared by the following preparation method:

[0026] The trihydroxymethylpropane, the dihydroxymethylbutyric acid, and the 2,2-difluoro-3-hydroxy-succinic acid and a catalyst are added to a reactor, reacted under the condition of refluxing of an aryl solvent, and distilled under reduced pressure to obtain the fluorine-containing hydroxyl-terminated hyperbranched polymer.

[0027] Preferably, the aryl solvent is at least one of toluene and xylene, and the reaction time is 4-10 h;

[0028] The catalyst is p-methyl benzene sulfonic acid, and the amount of addition is 1-3wt% of the total mass of monomers.

[0029] Compared with the prior art, the beneficial effects of the present application at least include:

[0030] First, the sealing glue of the present application has excellent comprehensive performance due to the reasonable optimization of the formula, especially the addition of self-made fluorine-containing hyperbranched hydroxyl-terminated polymer, and can simultaneously consider the mechanical properties, waterproof properties and aging resistance of the sealing glue. It still has excellent performance under high temperature and high humidity, high salt mist conditions, and the waterproof and electrical insulation properties reach the national power grid standard, and can be used for waterproof packaging protection of high and low voltage cable joint cold shrink tube position.

[0031] Second, the cold shrink tube sealing glue for aging-resistant cables of the present application is convenient to construct, and no treatment is needed for the cold shrink tube before construction of the waterproof sealing layer. When used, the sealing mortar is only needed to be filled or brushed to the cable joint, such as the two ends in the cold shrink tube, fully wetted and then completely cured, so as to improve the adhesion between the cold shrink tube and the outer semiconductive layer and prevent water from entering the conductor area of the cable joint. When used, it can be directly pressed to the appropriate shape by hand, and can be cured at room temperature for 10-20h. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is the preparation flow chart of the sealing glue of the present application;

[0033] Figure 2 is the construction drawing of the sealing glue of the present application. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. The embodiments described in the present application are only a part of the embodiments of the present application, not all the embodiments. All other embodiments obtained by those skilled in the art without creative labor based on the spirit of the present application are within the protection scope of the present application.

[0035] Unless otherwise specified, the "parts" in the embodiments of the present application are all mass parts, and the "%" is all mass percentage.

[0036] The embodiments of the present application provide a sealing glue for aging-resistant cable joints, which comprises the following mass parts of raw materials: 35-50 parts of hydroxyl silicone oil, 45-60 parts of filler, 3-5 parts of fumed white carbon black, 2-5 parts of fluorine-containing hydroxyl-terminated hyperbranched polymer; 3-6 parts of hydrogen-containing silicone oil, 1-5 parts of silane coupling agent, 1-3 parts of ketone oxime crosslinking agent, 0.05-0.1 parts of organic tin catalyst, 0.1-0.2 parts of lubricant and 1-3 parts of carbon black.

[0037] The cold shrink tube sealant and the cold shrink tube provided by the present application have very good adhesion, are quickly compatible and fully wet when applied on the surface of the cold shrink tube, break through the effect that traditional adhesives cannot form adhesion with the surface of the cold shrink tube, and improve the adhesion of the cold shrink tube and the outer semi-conductive layer.

[0038] The fluorine-containing end-hydroxyl hyperbranched polymer is prepared by using trihydroxymethylpropane, dihydroxymethyl butyric acid and 2,2-difluoro-3-hydroxy-succinic acid (CAS registration number: 137524-39-1) as monomers.

[0039] Further, the molar ratio of trihydroxymethylpropane, dihydroxymethyl butyric acid and 2,2-difluoro-3-hydroxy-succinic acid is 1:7-9:1-2.

[0040] Further, the fluorine-containing end-hydroxyl hyperbranched polymer is prepared by a preparation method comprising the following steps: trihydroxymethylpropane, dihydroxymethyl butyric acid and 2,2-difluoro-3-hydroxy-succinic acid and a catalyst p-toluenesulfonic acid are added to a reactor, reacted under the condition of refluxing of an aromatic solvent, and distilled under reduced pressure to obtain the fluorine-containing end-hydroxyl hyperbranched polymer.

[0041] In the preferred but non-limiting embodiments of the present application, the aromatic solvent is at least one selected from toluene and xylene, and the reaction time is 4-10h.

[0042] The amount of p-toluenesulfonic acid added is 1-3wt% of the total mass of the monomers (the total mass of trihydroxymethylpropane, dihydroxymethyl butyric acid and 2,2-difluoro-3-hydroxy-succinic acid), such as 2wt%.

[0043] The inventors unexpectedly found that adding a certain amount of fluorine-containing end-hydroxyl hyperbranched polymer to the silicone sealant can simultaneously improve the mechanical properties, waterproof performance and aging resistance of the sealant after curing.

[0044] Further, the hydroxyl silicone oil is obtained by compounding end-hydroxyl silicone oil and side-chain hydroxyl silicone oil at a mass ratio of 6-8:1, the end-hydroxyl silicone oil has a hydroxyl content of 0.7-1.2wt%, and the side-chain hydroxyl silicone oil has a hydroxyl content of 5-8wt%. The inventors found that the hydroxyl silicone oil compounded in the above manner has the best comprehensive performance as the main component of the sealant silicone.

[0045] Further, the active hydrogen content of the hydrogen-containing silicone oil is 0.5-0.7mmol / g, and the viscosity is 10000-100000cst, such as 30000-50000cst. The hydroxyl silicone oil and the hydrogen-containing silicone oil are both purchased from Bluestar Silicones.

[0046] The silane coupling agent is a compound of fluorine-containing silane coupling agent and epoxy silane coupling agent, and the mass ratio of the two is 1-2:2-5.

[0047] In the preferred but non-limiting embodiment of the present application, the fluorine-containing silane coupling agent is selected from at least one of tridecafluorooctyltrimethoxysilane and heptadecafluorodecyltriethoxysilane.

[0048] The epoxy silane coupling agent is selected from at least one of 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-glycidyloxypropylmethyldimethoxysilane, 3-glycidyloxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

[0049] The lubricant is selected from at least one of polyethylene wax and polypropylene wax, which is used to improve the processing performance of the resin.

[0050] The filler is selected from at least one of calcium carbonate, magnesium carbonate, dolomite, clay and talc powder, and the particle size of the filler is 1-100 μm, preferably 10-50 μm.

[0051] The organic tin catalyst is selected from at least one of butyltin dilaurate, dioctyltin dilaurate, dibutyltin diacetate and stannous octoate.

[0052] The ketoxime crosslinking agent is selected from at least one of methyltributanoxysilane, vinyltributanoxysilane, phenyltributanoxysilane and methyltetrabutanoxysilane.

[0053] The specific surface area of the fumed white carbon black is 150-180 m 2 / g, the surface of the fumed white carbon black has hydroxyl groups, and can form a crosslinked network structure through chemical bonds or hydrogen bonds. The fumed white carbon black not only serves as a filler to improve the mechanical properties of the sealant, but also serves as a crosslinking agent.

[0054] The larger the specific surface area of the fumed white carbon black is, the stronger the role of the fumed white carbon black as a crosslinking agent is, and the better the mechanical properties and aging resistance are. However, if the specific surface area is too large, the water absorption will be enhanced, which is not conducive to the formation of a crosslinked network. Therefore, selecting a suitable specific surface area is also crucial. Through the inventor's extensive practice, it is appropriate to select the specific surface area of the fumed white carbon black to be 150-180 m 2 / g.

[0055] As Figure 1 shown in the drawings, another embodiment of the present application provides a preparation method of a sealant for an aging-resistant cable joint, based on the sealant for an aging-resistant cable joint, comprising the following steps:

[0056] The hydroxyl silicone oil and the filler are mixed uniformly in a planetary mixer under closed conditions while being heated and degassed, then the fumed white carbon black, the fluorine-containing hydroxyl-terminated hyperbranched polymer, the hydrogen-containing silicone oil, the silane coupling agent, the ketone oxime crosslinking agent, the lubricant and the carbon black are added and mixed uniformly, finally the organotin catalyst is added, vacuum extraction is continued and mixing is uniform, and the aging-resistant cable cold shrink tube sealant is obtained by extrusion.

[0057] The heating condition of the heating and degassing is 110°C for 1 hour and negative pressure of 0.1 MPa.

[0058] As shown in the sealant construction drawing of the present application, Figure 2 The cable cold shrink tube waterproof sealant does not need any treatment of the cold shrink tube before construction, only needs to coat the interface agent on the outer semiconductive layer, and then the waterproof seal layer can be constructed. When used, it can be directly pressed to the appropriate shape by hand, and can be cured at room temperature for 10-20 h.

[0059] When used, the cable cold shrink tube waterproof sealant should be applied by hand or by scraping, and the product should be uniformly applied at the interface between the cable cold shrink tube and the outer semiconductive layer. During construction, the sealant should be applied in place at one time, and should be waterproof, sun-proof, pollution-proof, movement-proof, and bending-proof. The cable cold shrink tube waterproof sealant should be applied in an arc shape at the interface, and should not have obvious steps, so as to ensure the waterproof effect. After application, the next step of restoring the cable intermediate joint can be carried out, and the cable cold shrink tube waterproof sealant should not be touched in the subsequent process.

[0060] Preparation Example 1

[0061] The monomers of trihydroxymethylpropane, dihydroxymethylbutyric acid and 2,2-difluoro-3-hydroxy-butane dicarboxylic acid are added in a molar ratio of 1:7:2, 2wt% of p-methylbenzenesulfonic acid is added as a catalyst, xylene is added as a solvent and a water-carrying agent, and the reaction is carried out under reflux conditions for 5 h, and then vacuum distillation is carried out to obtain the fluorine-containing hydroxyl-terminated hyperbranched polymer.

[0062] Preparation Example 2

[0063] The other conditions are the same as those in Preparation Example 1, and the difference lies in that the molar ratio of trihydroxymethylpropane, dihydroxymethylbutyric acid and 2,2-difluoro-3-hydroxy-butane dicarboxylic acid is 1:9:1.

[0064] Comparative Preparation Example 1

[0065] The other conditions are the same as those in Preparation Example 1, and the difference lies in that the monomers are a mixture of trihydroxymethylpropane and dihydroxymethylbutyric acid in a molar ratio of 1:9, and 2,2-difluoro-3-hydroxy-butane dicarboxylic acid is not added.

[0066] Example 1

[0067] In a closed condition, 50 parts of hydroxyl silicone oil (mixed hydroxyl silicone oil with 1 wt% end hydroxyl silicone oil and 6 wt% side chain hydroxyl silicone oil in a mass ratio of 6:1), 30 parts of calcium carbonate with a particle size of 20 μm, and 20 parts of talc with a particle size of 50 μm were uniformly mixed in a planetary mixer. Then, the mixture was heated to 120°C under a vacuum of 100 Pa to perform heat degassing. After cooling, 5 parts of fumed white carbon black with a specific surface area of 150 m2 / g, 5 parts of the fluorine-containing end hydroxyl hyperbranched polymer prepared in Preparation Example 1, 4 parts of hydrogen-containing silicone oil (active hydrogen content of 0.5 mmol / g, viscosity of about 40,000 cst), 2 parts of a silane coupling agent (a mixture of tridecafluoro-octyltrimethoxysilane and 3-glycidyl ether propyltrimethoxysilane in a mass ratio of 1:2), 2 parts of methyltributyloctyloxysilane, 0.2 parts of polyethylene wax, and 2 parts of carbon black were uniformly mixed. Finally, 0.1 part of butyltin dilaurylate was added, vacuum was applied, and the mixture was uniformly mixed by stirring. The mixture was extruded by an extruder to obtain a cold shrink tube sealant for an aging-resistant cable. 2 / g, 5 parts of the fluorine-containing end hydroxyl hyperbranched polymer prepared in Preparation Example 1, 4 parts of hydrogen-containing silicone oil (active hydrogen content of 0.5 mmol / g, viscosity of about 40,000 cst), 2 parts of a silane coupling agent (a mixture of tridecafluoro-octyltrimethoxysilane and 3-glycidyl ether propyltrimethoxysilane in a mass ratio of 1:2), 2 parts of methyltributyloctyloxysilane, 0.2 parts of polyethylene wax, and 2 parts of carbon black were uniformly mixed. Finally, 0.1 part of butyltin dilaurylate was added, vacuum was applied, and the mixture was uniformly mixed by stirring. The mixture was extruded by an extruder to obtain a cold shrink tube sealant for an aging-resistant cable.

[0068] Example 2

[0069] The other conditions were the same as in Example 1, except that the fluorine-containing end hydroxyl hyperbranched polymer was prepared in Preparation Example 2.

[0070] Example 3

[0071] The other conditions were the same as in Example 1, except that the hydroxyl silicone oil was mixed hydroxyl silicone oil with 0.7 wt% end hydroxyl silicone oil and 5 wt% side chain hydroxyl silicone oil in a mass ratio of 8:1.

[0072] Example 4

[0073] The other conditions were the same as in Example 1, except that the hydroxyl silicone oil was 86 parts of 1 wt% end hydroxyl silicone oil.

[0074] Example 5

[0075] The other conditions were the same as in Example 1, except that the hydroxyl silicone oil was 15 parts of 6 wt% side chain hydroxyl silicone oil.

[0076] Example 6

[0077] The other conditions were the same as in Example 1, except that the amount of hydroxyl silicone oil was 35 parts, the fillers were 25 parts of calcium carbonate with a particle size of 20 μm and 20 parts of talc with a particle size of 50 μm, the amount of fumed white carbon black was 3 parts, the specific surface area of the fumed white carbon black was 180 m2 / g, the amount of the fluorine-containing end hydroxyl hyperbranched polymer prepared in Preparation Example 1 was 2 parts, and the amount of hydrogen-containing silicone oil was 3 parts, and the active hydrogen content of the hydrogen-containing silicone oil was 0.7 mmol / g. 2 / g, the amount of the fluorine-containing end hydroxyl hyperbranched polymer prepared in Preparation Example 1 was 2 parts, and the amount of hydrogen-containing silicone oil was 3 parts, and the active hydrogen content of the hydrogen-containing silicone oil was 0.7 mmol / g.

[0078] Comparative Example 1

[0079] Other conditions and example 1 are the same, the difference is that the fluorine-containing hydroxyl-terminated hyperbranched polymer is prepared by comparative preparation example 1.

[0080] Comparative example 2

[0081] Other conditions and example 1 are the same, the difference is that the fluorine-containing hydroxyl-terminated hyperbranched polymer is replaced by equal mass of castor oil modified polyol CY-750.

[0082] Application example

[0083] The sealant obtained by the above examples and comparative examples is tested for the following performance, and the results are shown in Table 1 below.

[0084] The standard of tensile strength and elongation at break can refer to GB / T 528-2009; the electric breakdown refers to GB / T 1408.1-2016.

[0085] Wet heat resistance: under the condition of double 85 (85℃, 85RH%), the experimental period is 60 days, and the resistance and mechanical properties after double 85 test are tested.

[0086] Salt spray resistance: under the condition of neutral salt spray at 45±2℃, 50±5RH%, for 20 days, and then test the corrosion. According to the corrosion area, no corrosion is first class, <2% corrosion is second class, <5% corrosion is third class, <10% corrosion is third class, and >10% corrosion is unqualified.

[0087] Table 1 Performance test of sealant

[0088]

[0089]

[0090] From the test results in the above table, compared with the comparative examples, the sealant in the examples shows good performance in each performance test, especially in tensile strength, elongation at break, electric breakdown strength and performance retention after double 85 test.

[0091] Compared with the prior art, the beneficial effects of the present application at least include:

[0092] Firstly, the sealant of the present application is prepared by reasonable optimization of the formula, especially by adding self-made fluorine-containing hyperbranched hydroxyl-terminated polymer, and the prepared sealant has excellent comprehensive performance, which can simultaneously consider the mechanical properties, waterproof performance and aging resistance of the sealant, and still has excellent performance under high temperature and high humidity, high salt spray conditions, and the waterproof and electric insulation performance reaches the national grid standard, and can be used for waterproof packaging protection of high and low voltage cable joint cold shrink tube position.

[0093] Secondly, the cold shrink tube sealing glue for the aging-resistant cable is convenient to construct, and the waterproof sealing layer can be constructed without any treatment of the cold shrink tube before the waterproof sealing glue for the cable is constructed. When in use, the sealing mortar is filled or brushed to the cable joint, such as the two ends in the cold shrink tube, is fully wetted and then is completely solidified, the adhesion between the cold shrink tube and the outer semiconductive layer is improved, and water is prevented from entering the conductor area of the cable intermediate joint. When in use, the sealing mortar can be directly pressed by hand to a suitable shape, and is solidified at normal temperature for 10-20h.

[0094] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and not to limit them. Although the present application has been described in detail with reference to the above examples, those skilled in the art should understand that the specific embodiments of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the present application, and any modification or equivalent replacement should be covered within the protection scope of the claims of the present application.

Claims

1. A sealant for aging-resistant cable joints, characterized in that: The raw materials include the following parts by weight: 35-50 parts hydroxyl silicone oil, 45-60 parts filler, 3-5 parts fumed silica, 2-5 parts fluorine-containing hydroxyl-terminated hyperbranched polymer; 3-6 parts hydrogen-containing silicone oil, 1-5 parts silane coupling agent, 1-3 parts ketoxime crosslinking agent, 0.05-0.1 parts organotin catalyst, 0.1-0.2 parts lubricant, and 1-3 parts carbon black; The fluorinated hydroxyl-terminated hyperbranched polymer was prepared using trihydroxymethylpropane, dihydroxymethylbutyric acid and 2,2-difluoro-3-hydroxy-succinic acid as monomers.

2. The aging-resistant cable joint sealant according to claim 1, characterized in that, The molar ratio of trihydroxymethylpropane, dihydroxymethylbutyric acid and 2,2-difluoro-3-hydroxy-succinic acid is 1:7-9:1-2.

3. The aging-resistant cable joint sealant according to claim 1, characterized in that, The hydroxyl silicone oil is a compound of terminal hydroxyl silicone oil and side-chain hydroxyl silicone oil in a mass ratio of 6-8:1, wherein the hydroxyl content of the terminal hydroxyl silicone oil is 0.7-1.2 wt%, and the hydroxyl content of the side-chain hydroxyl silicone oil is 5-8 wt%.

4. The aging-resistant cable joint sealant according to claim 1, characterized in that, The hydrogen-containing silicone oil has an active hydrogen content of 0.5-0.7 mmol / g and a viscosity of 10,000-100,000 cst.

5. The aging-resistant cable joint sealant according to claim 1, characterized in that, The silane coupling agent is a mixture of fluorinated silane coupling agent and epoxy silane coupling agent in a mass ratio of 1-2:2-5.

6. The aging-resistant cable joint sealant according to claim 5, characterized in that, The fluorinated silane coupling agent is at least one of tridecafluorooctyltrimethoxysilane and heptadecafluorodecyltriethoxysilane; The epoxy silane coupling agent is at least one of 3-glycidyl etheroxypropyltrimethoxysilane, 3-glycidyl etheroxypropyltriethoxysilane, 3-glycidyl etheroxypropylmethyldimethoxysilane, 3-glycidyl etheroxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

7. The aging-resistant cable joint sealant according to claim 1, characterized in that, The lubricant is selected from at least one of polyethylene wax and polypropylene wax; The filler is selected from at least one of calcium carbonate, magnesium carbonate, dolomite, clay, and talc, and the particle size of the filler is 1-100 μm. The organotin catalyst is selected from at least one of butyltin dilaurate, dioctyltin dilaurate, dibutyltin diacetate, and stannous octoate. The ketoxime crosslinking agent is selected from at least one of methyltributanone oxime silane, vinyltributanone oxime silane, and phenyltributanone oxime silane; The specific surface area of ​​the fumed silica is 150-180 m². 2 / g.

8. A method for preparing the aging-resistant cable joint sealant according to any one of claims 1-7, characterized in that, Includes the following steps: Under closed conditions, hydroxyl silicone oil and filler are mixed evenly in a container while being heated to degas; Add fumed silica, fluorinated hydroxyl-terminated hyperbranched polymer, hydrogen-containing silicone oil, silane coupling agent, ketoxime crosslinking agent, lubricant and carbon black, and mix evenly; Add organotin catalyst, vacuum and continue stirring to mix evenly, then extrude by machine to obtain cold shrink tubing sealant for aging resistant cables.

9. The method for preparing the aging-resistant cable joint sealant according to claim 8, characterized in that, The fluorine-terminated hydroxyl-terminated hyperbranched polymer was prepared by the following method: Trimethylolpropane, dimethylolbutyric acid, 2,2-difluoro-3-hydroxy-succinic acid, and a catalyst were added to a reactor and reacted under reflux conditions with an aryl solvent. The mixture was then distilled under reduced pressure to obtain a fluorinated hyperbranched polymer with terminal hydroxyl groups.

10. The method for preparing the aging-resistant cable joint sealant according to claim 9, characterized in that, The aryl solvent is at least one of toluene and xylene, and the reaction time is 4-10 h. The catalyst is p-toluenesulfonic acid, and its addition amount is 1-3 wt% of the total mass of the monomers.

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