Sealant for aging-resistant cable joint and preparation method thereof

Abstract

The invention discloses an aging-resistant sealant for cable joints and a preparation method thereof, and belongs to the technical field of sealants, the aging-resistant sealant for cable joints comprises the following raw materials by mass: 35-50 parts of hydroxyl silicone oil, 45-60 parts of a filler, 3-5 parts of fumed silica, and 2-5 parts of a fluorine-containing hydroxyl-terminated hyperbranched polymer; 3-6 parts of hydrogen-containing silicone oil, 1-5 parts of a silane coupling agent, 1-3 parts of a ketoxime cross-linking agent, 0.05-0.1 part of an organic tin catalyst, 0.1-0.2 part of a lubricant and 1-3 parts of carbon black; the fluorine-containing hydroxyl-terminated hyperbranched polymer is prepared by taking trimethylolpropane, dimethylolbutyric acid and 2, 2-difluoro-3-hydroxy-succinic acid as monomers. The sealant disclosed by the invention has excellent comprehensive performance and aging resistance, and still has excellent performance under the conditions of high temperature, high humidity and high salt mist.

Description

Technical Field

[0001] The invention belongs to the technical field of sealants, and in particular relates to a sealant for an aging-resistant cable joint and a preparation method thereof. Background Art

[0002] Cable joints are key components for connecting the lines of various electrical equipment. The ends of the cold shrink tube are the weak points of the cable middle joint. Due to the breathing effect of the cable middle joint, water and other pollutants may enter the cold shrink tube from both ends, causing the insulation strength inside the joint to decrease, which may destroy the internal electric field balance and cause material aging and other problems. In serious cases, electrical tree aging, cable breakdown, and even cable explosion accidents may occur.

[0003] Therefore, high quality requirements are placed on cable cold shrink tube sealants. In particular, some electrical equipment is placed in an environment that is prone to sealant aging for a long time, such as high temperature, high humidity, high salt fog, and areas with large temperature differences between morning and evening. Poor sealing can easily lead to water vapor intrusion, and the sealant needs to maintain good waterproof and mechanical properties after various aging conditions in a humid environment.

[0004] At present, the main sealants for cables are silicone rubber, epoxy resin, and polyurethane. Epoxy resin and polyurethane generally require two components, and have strict requirements on curing conditions and high requirements on construction technology. Moreover, polyurethane sealants are easily corroded by fungi, resulting in poor performance. Silicone rubber is the most widely used due to its excellent performance in various aspects. CN107365503A discloses a waterproof cable water-blocking sealant, which is composed of 100 parts of methyl vinyl silicone rubber, 10 to 25 parts of fumed silica, 25 to 30 parts of calcium bicarbonate, 5 to 10 parts of rutile titanium dioxide, 1 to 5 parts of zinc stearate, and 5 to 10 parts of aniline methyl triethoxysilane according to mass ratio, and is mechanically stirred at 25°C for 20 to 30 minutes, and then 0.5 to 1 parts of a mixture of dibutyltin dilaurate curing agent and dibutyl phthalate are added to form a finished sealant. CN106590517A discloses a sealant, which is mainly made of 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 decabromodiphenylethane, 200-1000 parts of calcium carbonate, and 100-500 parts of talc. CN105153993A discloses an intumescent fireproof sealant, which is composed of the following raw materials in parts by weight: 70-90 parts of 50000cp α, ω-dihydroxy polydimethylsiloxane, 10-30 parts of 2000cp α, ω-dihydroxy polydimethylsiloxane, 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-aminopropyl triethoxysilane, 1-3 parts of vinyl tributanoximosilane, 3-7 parts of methyl trimethyloxysilane, 1-3 parts of acrylic acid-methacrylate, 1-2 parts of butyl titanate, and 0.3-1 parts of dibutyl tin dilaurate.

[0005] However, the above-mentioned sealants in the prior art have poor weather resistance, especially cannot withstand the harsh environment of high temperature and high humidity for a long time, and are not resistant to water vapor erosion at high temperature, resulting in a decrease in internal insulation strength, and in serious cases, accidents such as cable breakdown may occur. Therefore, it is necessary to develop a sealant with excellent comprehensive performance, mechanical properties, waterproofness and aging resistance. Summary of the invention

[0006] In order to solve the deficiencies in the prior art, the present invention provides an aging-resistant sealant for cable joints, which is a new type of single-component cable-specific waterproof sealant. When applied to the surface of the cold shrink tube, it is fully moistened and then completely cured, thereby improving the adhesion between the cold shrink tube and the outer semi-conductive layer, and preventing water from entering the conductor area of ​​the cable intermediate joint. At the same time, it has excellent aging resistance, and still has excellent performance under high temperature, high humidity, and high salt fog conditions, and its waterproof and electrical insulation properties meet the national grid standards. It can be used in the construction scenario of waterproof packaging protection of the cold shrink tube position of high and low voltage cable joints.

[0007] The present invention adopts the following technical solution.

[0008] The first aspect of the present invention discloses a sealant for an aging-resistant cable joint, comprising the following raw materials in parts by mass: 35-50 parts of hydroxy silicone oil, 45-60 parts of filler, 3-5 parts of fumed silica, 2-5 parts of fluorine-containing terminal hydroxyl hyperbranched polymer; 3-6 parts of hydrogenated 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 terminal hydroxyl hyperbranched polymer is prepared by 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 hydroxy silicone oil is a compound of terminal hydroxy silicone oil and side chain hydroxy silicone oil in a mass ratio of 6-8:1, the terminal hydroxy silicone oil has a hydroxy content of 0.7-1.2wt%, and the side chain hydroxy silicone oil has a hydroxy content of 5-8wt%.

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

[0013] Preferably, the silane coupling agent is a compound of a fluorine-containing silane coupling agent and an 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 epoxysilane coupling agent is at least one of 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-glycidyloxypropylmethyldimethoxysilane, 3-glycidyloxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

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

[0017] 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;

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

[0019] The ketoxime crosslinking agent is selected from at least one of methyltributylacetoximosilane, vinyltributylacetoximosilane, phenyltributylacetoximosilane and methyltetrabutylketoximesilane;

[0020] The specific surface area of ​​the fumed silica is 150-180 m 2 / g.

[0021] The second aspect of the present invention discloses a method for preparing a sealant for an aging-resistant cable joint, comprising the following steps:

[0022] Under closed conditions, hydroxy silicone oil and filler are mixed evenly in a container and heated for degassing at the same time;

[0023] Add fumed silica, fluorine-containing terminal hydroxyl hyperbranched polymer, hydrogen-containing silicone oil, silane coupling agent, ketoxime crosslinking agent, lubricant and carbon black, and mix well;

[0024] Add an organic tin catalyst, evacuate the mixture and continue stirring to mix evenly, and extrude it by machine to obtain a cold shrink tube sealant for aging-resistant cables.

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

[0026] Trihydroxymethylpropane, dihydroxymethylbutyric acid, 2,2-difluoro-3-hydroxy-succinic acid and a catalyst are added into a reactor, reacted under reflux conditions of an aromatic solvent, and distilled under reduced pressure to obtain a fluorine-containing terminal hydroxyl hyperbranched polymer.

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

[0028] The catalyst is p-toluenesulfonic acid, and its addition amount is 1-3wt% of the total weight of the monomers.

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

[0030] 1. The sealant of the present invention has excellent comprehensive performance through reasonable optimization of the formula, especially the addition of homemade fluorine-containing hyperbranched terminal hydroxyl polymer, and can take into account the mechanical properties, waterproof properties and aging resistance of the sealant at the same time. It still has excellent performance under high temperature, high humidity and high salt fog conditions. The waterproof and electrical insulation properties meet the national grid standards and can be used in the construction scenario of waterproof packaging protection of high and low voltage cable joint cold shrink tubes.

[0031] Second, the aging-resistant cable cold shrink tube sealant of the present invention is easy to construct. Before the construction of the cable cold shrink tube waterproof sealant, the cold shrink tube does not need to be treated in any way, and the waterproof sealing layer can be constructed. When in use, it is only necessary to fill or apply the sealing glue to the cable joint, such as the two ends of the cold shrink tube, fully wet it and then completely cure it, so as to improve the bonding force between the cold shrink tube and the outer semi-conductive layer and prevent water from entering the conductor area of ​​the cable middle joint. When in use, it can be directly pressed by hand to a suitable shape and cured at room temperature for 10-20 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a flow chart for preparing the sealant of the present invention;

[0033] Figure 2 It is the construction drawing of the sealant of the present invention. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only embodiments of a part of the present invention, rather than all embodiments. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0035] Unless otherwise specified, the “parts” in the embodiments of the present invention are parts by mass, and the “%” are percentages by mass.

[0036] An embodiment of the present invention provides a sealant for an aging-resistant cable joint, comprising the following raw materials in parts by mass: 35-50 parts of hydroxyl silicone oil, 45-60 parts of filler, 3-5 parts of fumed silica, 2-5 parts of fluorine-containing terminal hydroxyl hyperbranched polymer; 3-6 parts of hydrogenated 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.

[0037] The cold shrink tube sealant provided by the present invention has very good bonding strength with the cold shrink tube. When applied on the surface of the cold shrink tube, it is quickly compatible and fully wetted, breaking through the effect that traditional adhesives cannot form bonding strength with the surface of the cold shrink tube, and improving the bonding strength between the cold shrink tube and the outer semi-conductive layer.

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

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

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

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

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

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

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

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

[0046] The silane coupling agent is obtained by compounding a fluorine-containing silane coupling agent and an epoxy silane coupling agent in a mass ratio of 1-2:2-5;

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

[0048] The epoxysilane 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, and 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, 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 methyltributylacetoximosilane, vinyltributylacetoximosilane, phenyltributylacetoximosilane and methyltetrabutylketoximesilane.

[0053] The specific surface area of ​​the fumed silica is 150-180 m 2 / g, the surface of fumed silica has hydroxyl groups, which can form a cross-linked network structure through chemical bonds and hydrogen bonds. Fumed silica is used as a filler in sealants to improve the mechanical properties of sealants and as a cross-linking agent.

[0054] The larger the specific surface area of ​​fumed silica, the stronger its role as a crosslinking agent, and the better its mechanical properties and aging resistance. However, if the specific surface area is too large, it will increase its water absorption, which is not conducive to the formation of a crosslinking network. Therefore, choosing an appropriate specific surface area is also key. After a lot of practice by the inventors, 150-180m 2 / g is appropriate.

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

[0056] Under closed conditions, hydroxy silicone oil and filler are mixed evenly in a planetary mixer and heated for degassing at the same time, then gas phase silica, fluorine-terminated hydroxyl hyperbranched polymer, hydrogen-containing silicone oil, silane coupling agent, ketoxime crosslinking agent, lubricant and carbon black are added, mixed evenly, and finally an organic tin catalyst is added, vacuum is drawn and stirring is continued to mix evenly, and an aging-resistant cable cold shrink tube sealant is obtained by extrusion.

[0057] The heating conditions for the heating degassing are 110° C., 1 hour, and a negative pressure of 0.1 MPa.

[0058] like Figure 2 As shown in the figure, it is the construction drawing of the sealant of the present invention. Before the construction of the cable cold shrink tube waterproof sealant, no treatment is required on the cold shrink tube. Only the interface agent is applied to the outer semi-conductive layer to construct the waterproof sealing layer. When using, it can be directly pressed by hand into a suitable shape and cured at room temperature for 10-20 hours.

[0059] The cable cold shrink tube waterproof sealant should be applied by hand or scraper, and the product should be evenly applied to the interface between the cable cold shrink tube and the outer semi-conductive layer. During the construction process, the sealant should be applied in one go, and it 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 there should not be obvious steps to ensure the waterproof effect. After the application is completed, the next step can be carried out to restore the middle joint of the cable, and ensure that the subsequent process does not touch the cable cold shrink tube waterproof sealant.

[0060] Preparation Example 1

[0061] Trihydroxymethylpropane, dihydroxymethylbutyric acid and 2,2-difluoro-3-hydroxy-succinic acid are added in a molar ratio of 1:7:2, 2wt% of the total mass of the monomers is added as a catalyst, xylene is added as a solvent and a water-carrying agent, the reaction is carried out under reflux conditions for 5 hours, and reduced pressure distillation is performed to obtain a fluorine-containing terminal hydroxyl hyperbranched polymer.

[0062] Preparation Example 2

[0063] The other conditions were the same as those in Preparation Example 1, except that the molar ratio of trihydroxymethylpropane, dihydroxymethylbutyric acid and 2,2-difluoro-3-hydroxy-succinic acid was 1:9:1.

[0064] Comparative Preparation Example 1

[0065] The other conditions were the same as those in Preparation Example 1, except that the monomer was a mixture of trihydroxymethylpropane and dihydroxymethylbutyric acid in a molar ratio of 1:9, and 2,2-difluoro-3-hydroxy-succinic acid was not added.

[0066] Example 1

[0067] Under closed conditions, 50 parts of hydroxy silicone oil (a mixed hydroxy silicone oil of 1 wt% terminal hydroxy silicone oil and 6 wt% side chain hydroxy silicone oil in a mass ratio of 6:1) and 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 mixed evenly in a planetary mixer, and then heated to 120°C under a vacuum condition of 100 Pa for heating and degassing. After cooling, 5 parts of a silica gel with a specific surface area of ​​150 m 2 / g of fumed silica, 5 parts of fluorine-terminated hydroxyl hyperbranched polymer obtained in Preparation Example 1, 4 parts of hydrogen-containing silicone oil (active hydrogen content is 0.5mmol / g, viscosity is about 40000cst), 2 parts of silane coupling agent (tridecafluorooctyltrimethoxysilane and 3-glycidyloxypropyltrimethoxysilane are compounded in a mass ratio of 1:2), 2 parts of methyl tributylidene oxime silane, 0.2 parts of polyethylene wax, and 2 parts of carbon black are mixed evenly, and finally 0.1 parts of butyl tin dilaurate are added, and the mixture is vacuumed and stirred to be evenly mixed, and an aging-resistant cable cold shrink tube sealant is obtained by extrusion.

[0068] Example 2

[0069] The other conditions are the same as those in Example 1, except that the fluorinated hydroxyl-terminated hyperbranched polymer is prepared in Preparation Example 2.

[0070] Example 3

[0071] Other conditions are the same as those in Example 1, except that the hydroxy silicone oil is a mixed hydroxy silicone oil of terminal hydroxy silicone oil with a hydroxy content of 0.7 wt % and side chain hydroxy silicone oil with a hydroxy content of 5 wt % in a mass ratio of 8:1.

[0072] Example 4

[0073] The other conditions are the same as those in Example 1, except that the hydroxy silicone oil is 86 parts of 1 wt % terminal hydroxy silicone oil.

[0074] Example 5

[0075] The other conditions are the same as those in Example 1, except that the hydroxy silicone oil is 15 parts of 6 wt % side chain hydroxy silicone oil.

[0076] Example 6

[0077] The other conditions are the same as those in Example 1, except that the amount of hydroxy silicone oil is 35 parts, the filler is 25 parts of calcium carbonate with a particle size of 20 μm, 20 parts of talc with a particle size of 50 μm, the amount of fumed silica is 3 parts, and the specific surface area is 180 m 2 / g, the amount of the fluorine-containing terminal hydroxyl hyperbranched polymer prepared in Preparation Example 1 is 2 parts, the amount of hydrogen-containing silicone oil is 3 parts, and the active hydrogen content is 0.7mmol / g.

[0078] Comparative Example 1

[0079] Other conditions are the same as those in Example 1, except that the fluorine-containing terminal hydroxyl hyperbranched polymer is prepared in Comparative Preparation Example 1.

[0080] Comparative Example 2

[0081] Other conditions were the same as those in Example 1, except that the fluorinated hydroxyl-terminated hyperbranched polymer was replaced with an equal mass of castor oil-modified polyol CY-750.

[0082] Application Examples

[0083] The sealants obtained in the above examples and comparative examples were subjected to the following performance tests, and the results are shown in Table 1 below.

[0084] The standards for tensile strength and elongation at break can refer to GB / T 528-2009; the standards for electrical breakdown can refer to GB / T1408.1-2016.

[0085] Moisture and heat resistance: Under double 85 (85℃, 85RH%) experimental conditions, experimental period: 60 days, test the resistance and mechanical properties after the double 85 experiment.

[0086] Salt spray resistance: Keep it in neutral salt spray conditions of 45±2℃, 50±5RH% for 20 days, then test the corrosion situation. According to the corrosion area, no corrosion is level one, corrosion of less than 2% is level two, corrosion of less than 5% is level three, corrosion of less than 10% is level three, and corrosion of more than 10% is unqualified.

[0087] Table 1 Sealant performance test

[0088]

[0089]

[0090] It can be seen from the test results in the above table that, compared with the comparative example, the sealant in the embodiment shows better performance in various performance tests, especially in tensile strength, elongation at break, electrical breakdown strength and performance retention after the double 85 test.

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

[0092] 1. The sealant of the present invention has excellent comprehensive performance through reasonable optimization of the formula, especially the addition of homemade fluorine-containing hyperbranched terminal hydroxyl polymer, and can take into account the mechanical properties, waterproof properties and aging resistance of the sealant at the same time. It still has excellent performance under high temperature, high humidity and high salt fog conditions. The waterproof and electrical insulation properties meet the national grid standards and can be used in the construction scenario of waterproof packaging protection of high and low voltage cable joint cold shrink tubes.

[0093] Second, the aging-resistant cable cold shrink tube sealant of the present invention is easy to construct. Before the construction of the cable cold shrink tube waterproof sealant, the cold shrink tube does not need to be treated in any way, and the waterproof sealing layer can be constructed. When in use, it is only necessary to fill or apply the sealing glue to the cable joint, such as the two ends of the cold shrink tube, fully wet it and then completely cure it, so as to improve the bonding force between the cold shrink tube and the outer semi-conductive layer and prevent water from entering the conductor area of ​​the cable middle joint. When in use, it can be directly pressed by hand to a suitable shape and cured at room temperature for 10-20 hours.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A sealant for aging-resistant cable joints, characterized in that: The invention comprises the following raw materials in parts by weight: 35-50 parts of hydroxy silicone oil, 45-60 parts of filler, 3-5 parts of fumed silica, 2-5 parts of fluorine-containing terminal hydroxyl hyperbranched polymer; 3-6 parts of hydrogenated 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; The fluorine-containing terminal hydroxyl hyperbranched polymer is prepared by using trihydroxymethylpropane, dihydroxymethylbutyric acid and 2,2-difluoro-3-hydroxy-succinic acid as monomers.

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

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

4. The sealant for aging-resistant cable joint according to claim 1, characterized in that: The active hydrogen content of the hydrogen-containing silicone oil is 0.5-0.7 mmol / g, and the viscosity is 10000-100000 cst.

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

6. The sealant for aging-resistant cable joint according to claim 5, characterized in that: The fluorine-containing silane coupling agent is at least one of tridecafluorooctyltrimethoxysilane and heptadecafluorodecyltriethoxysilane; The epoxysilane coupling agent is at least one of 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-glycidyloxypropylmethyldimethoxysilane, 3-glycidyloxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

7. The sealant for aging-resistant cable joint 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 methyltributylacetoximosilane, vinyltributylacetoximosilane, phenyltributylacetoximosilane and methyltetrabutylketoximesilane; The specific surface area of ​​the fumed silica is 150-180 m 2 / g.

8. The method for preparing the sealant for aging-resistant cable joints according to any one of claims 1 to 7, characterized in that: The following steps are involved: Under closed conditions, hydroxy silicone oil and filler are mixed evenly in a container and heated for degassing at the same time; Add fumed silica, fluorine-containing terminal hydroxyl hyperbranched polymer, hydrogen-containing silicone oil, silane coupling agent, ketoxime crosslinking agent, lubricant and carbon black, and mix well; Add an organic tin catalyst, evacuate the mixture and continue stirring to mix evenly, and extrude it by machine to obtain a cold shrink tube sealant for aging-resistant cables.

9. The method for preparing the sealant for aging-resistant cable joints according to claim 8, characterized in that: The fluorine-containing hydroxyl-terminated hyperbranched polymer is prepared by the following preparation method: Trihydroxymethylpropane, dihydroxymethylbutyric acid, 2,2-difluoro-3-hydroxy-succinic acid and a catalyst are added into a reactor, reacted under reflux conditions of an aromatic solvent, and distilled under reduced pressure to obtain a fluorine-containing terminal hydroxyl hyperbranched polymer.

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

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