A pressure-resistant, crack-resistant, fire-resistant cable insulation material and a preparation method thereof

Abstract

The present application relates to the technical field of cable insulation materials, specifically a pressure-resistant, crack-resistant, and fire-resistant cable insulation material and its preparation method, comprising: uniformly mixing polypropylene, 3-methacryloxypropyltrimethoxysilane, acrylonitrile-butadiene-styrene resin, modified polymethyl methacrylate resin, a flame retardant, and a cross-linking catalyst, heating and plasticizing to a molten state, injecting supercritical carbon dioxide as a foaming agent, and uniformly mixing the foaming agent with the molten composite material; placing a composite mesh layer skeleton into a mold cavity, pouring the molten composite material uniformly mixed with the foaming agent, foaming and molding, pressing, and electron irradiation treatment to obtain a pressure-resistant, crack-resistant, and fire-resistant cable insulation material. By selecting specific raw materials for combination and adopting a specific preparation method, the pressure-resistant, crack-resistant, and fire-resistant cable insulation material has good pressure resistance, crack resistance, and fire resistance while maintaining good insulation performance.

Description

Technical Field

[0001] The present application relates to the technical field of cable insulation materials, and in particular to a pressure-resistant, crack-resistant and fire-resistant cable insulation material and a preparation method thereof. Background Art

[0002] Cable insulation material is an important component of wires and cables. Its main function is to ensure that current does not leak into the external environment during transmission, while protecting the cable from damage from the external environment.

[0003] There are many types of existing cable insulation materials. For example, polyvinyl chloride insulation has good insulation and chemical resistance, but it is prone to accelerated aging under high temperature or strong sunlight, and becomes hard and brittle at low temperatures; rubber insulation has good oil resistance, good softness and elasticity, and can maintain good performance in low temperature environments, but has weak mechanical strength and poor aging resistance; silicone rubber cable insulation is resistant to high temperature, has good weather resistance and excellent electrical properties, but has insufficient wear resistance and corrosion resistance, and poor tear resistance. If it is squeezed or scraped by external force, it is easy to cause damage to the insulation layer, thereby causing safety hazards such as short circuits.

[0004] Therefore, there is an urgent need to provide a better cable insulation material that is not only safe and durable, but also has multiple functions such as pressure resistance, crack resistance, and fire resistance to meet different usage scenarios. Summary of the Invention

[0005] The present application aims to overcome at least one of the defects of the prior art and provide a pressure-resistant, crack-resistant and fire-resistant cable insulation material and a preparation method thereof. By selecting specific raw materials for combination and adopting a specific preparation method, the pressure-resistant, crack-resistant and fire-resistant cable insulation material produced has good pressure resistance, crack resistance and fire resistance while maintaining good insulation performance.

[0006] In a first aspect, the embodiments of the present application provide a pressure-resistant, crack-resistant, and fire-resistant cable insulation material, which is implemented by the following technical solutions:

[0007] A method for preparing a pressure-resistant, crack-resistant and fire-resistant cable insulation material comprises the following steps:

[0008] (1) uniformly mixing 60-80 parts of polypropylene, 1-3 parts of 3-methacryloxypropyltrimethoxysilane, 25-40 parts of acrylonitrile-butadiene-styrene resin, 10-20 parts of modified polymethyl methacrylate resin, 2-4 parts of a flame retardant, and 0.5-1 part of a cross-linking catalyst according to parts by weight to form a precursor of a composite material, and heating and plasticizing the composite material precursor at a temperature of 190° C. to 230° C. to achieve a molten state, thereby obtaining a fully mixed molten composite material;

[0009] (2) injecting supercritical carbon dioxide into the molten composite material as a foaming agent, and uniformly mixing the foaming agent and the molten composite material through strong shearing action;

[0010] (3) placing the composite mesh layer skeleton into the mold cavity, pouring the molten composite material uniformly mixed with the foaming agent, and then foaming and molding it, placing it in a twin-screw extruder to press the sheet, and performing electron irradiation treatment through an irradiation process to fully solidify it to obtain a pressure-resistant, crack-resistant and fire-resistant cable insulation material.

[0011] According to an embodiment of the present application, a method for preparing a pressure-resistant, crack-resistant and fire-resistant cable insulation material has at least the following beneficial effects:

[0012] The preparation method of the present application uses a silane coupling agent to cross-link polypropylene, transforming the linear structure of the polypropylene molecular chain into a three-dimensional network structure, thereby improving the mechanical properties, heat resistance, melt strength and creep resistance of the cross-linked polypropylene; and mixing it with acrylonitrile-butadiene-styrene and modified polymethyl methacrylate polymer materials to further improve the mechanical strength and aging resistance of the material.

[0013] The preparation method of the present application pours the molten material into the interior of the composite mesh layer skeleton and melts and bonds it, thereby enhancing the bonding effect, causing the fibers to entangle and bond with each other to form a high-strength reinforced skeleton, and enhancing the strength and crack resistance of the pressure-resistant, crack-resistant and fire-resistant cable insulation material.

[0014] The present application adopts microporous foam injection molding. After being poured into the mold cavity, due to the sudden pressure drop and thermodynamic instability, the foaming agent precipitates inside the composite material to form a large number of bubble nuclei. In the subsequent cooling and molding process, the bubble nuclei continue to grow and solidify to form a microporous structure. Microporous foam injection molding can effectively reduce costs and energy consumption. The prepared pressure-resistant, crack-resistant and fire-resistant cable insulation material has a large number of pore structures inside. The pore structure improves the pressure resistance of the pressure-resistant, crack-resistant and fire-resistant cable insulation material, and also has the characteristics of high specific strength and crack resistance. At the same time, the process is simple and the molding quality is high, which is suitable for industrial production.

[0015] According to some embodiments of the present application, the preparation of the modified polymethyl methacrylate resin in step (1) comprises the following steps:

[0016] 40-50 parts of polymethyl methacrylate resin, 0.4-0.6 parts of dicumyl peroxide and 1-2 parts of trihydroxypropane triacrylate are mixed uniformly in a high-speed mixer according to weight parts, added to a torque rheometer at a speed of 50-70 r / min, and reacted at 160-170° C. for 2-3 hours to obtain a modified polymethyl methacrylate resin.

[0017] By modifying the polymethyl methacrylate resin, trimethylolpropane triacrylate can be grafted into the molecular chain structure of polymethyl methacrylate. Through the participation of multiple double bonds in the same trimethylolpropane triacrylate molecule in the reaction, polymethyl methacrylate forms a cross-linked network structure, which broadens the molecular weight distribution of polymethyl methacrylate, thereby reducing its melt flow rate, having better thermal stability and faster cleaning rate during the foaming process, and being easier to process and shape.

[0018] According to some embodiments of the present application, the preparation of the composite mesh layer skeleton in step (3) includes the following steps: combing and laying basalt fibers to form a basalt fiber mesh layer, combing and laying aramid fibers to form an aramid fiber mesh layer, and then compounding the upper and lower surfaces of the basalt fiber mesh layer with a layer of aramid fiber mesh layer respectively, and using a front and back needle punching method to insert all the aramid fibers of the aramid fiber mesh layer into the interior of the basalt fiber mesh layer to obtain a composite mesh layer skeleton.

[0019] The basalt fiber of the present application has excellent modulus and strength, as well as good corrosion resistance, high temperature resistance, and wear resistance, and has excellent comprehensive performance; basalt fiber can also be radiation-proof, shock-proof, and resist fungal and microbial attacks, thereby increasing the service life of cable insulation materials; aramid fiber has excellent properties such as ultra-high strength, high modulus, high temperature resistance, acid and alkali resistance, light weight, aging resistance, and long life cycle, and can enhance the toughness and mechanical strength of pressure-resistant and crack-resistant cable insulation materials.

[0020] Furthermore, the basalt fiber is prepared by the following pretreatment method: sodium hydroxide and 3-aminopropyltriethoxysilane are mixed to form a pretreatment liquid; the basalt fiber is immersed in the pretreatment liquid, and the basalt fiber is fully immersed by ultrasonic treatment to obtain the pretreated basalt fiber.

[0021] Furthermore, the aramid fiber is prepared by the following pretreatment method: sodium hydroxide and 3-aminopropyltriethoxysilane are mixed to form a pretreatment solution; the aramid fiber is immersed in the pretreatment solution, and the aramid fiber is fully immersed by ultrasonic treatment to obtain the pretreated aramid fiber.

[0022] In this application, sodium hydroxide treatment is first used to significantly increase the roughness of the surface of the basalt fiber and the aramid fiber, making the bonding between them and the acrylonitrile-butadiene-styrene resin and the modified polymethyl methacrylate resin matrix tighter; 3-aminopropyltriethoxysilane can react with the basalt fiber, aramid fiber and the acrylonitrile-butadiene-styrene resin and the modified polymethyl methacrylate resin matrix respectively, so that a bridge-like covalent bond can be formed between the basalt fiber, the aramid fiber and the acrylonitrile-butadiene-styrene resin and the modified polymethyl methacrylate resin matrix, thereby improving the internal bonding stability of the pressure-resistant, crack-resistant and fire-resistant cable insulation material; ultrasonic treatment can fully impregnate the fiber, ensuring that the 3-aminopropyltriethoxysilane is evenly distributed on the surface of the basalt fiber and the aramid fiber.

[0023] Furthermore, the mass ratio of the aramid fiber to the basalt fiber is (2-3):(1-2).

[0024] Furthermore, the diameter of the aramid fiber is 10 μm-1000 μm.

[0025] Furthermore, the length of the aramid fiber is 1 cm-4 cm.

[0026] Furthermore, the diameter of the basalt fiber is 10 μm-1000 μm.

[0027] Furthermore, the length of the basalt fiber is 1 cm-4 cm.

[0028] According to some embodiments of the present application, the flame retardant in step (1) is a mixture of a phosphate flame retardant and fumed silica. When the material burns, silica can form a silica covering, which has the functions of insulation and shielding, and can prevent heat transfer and escape of combustibles. The addition of fumed silica can also increase the residual carbon content of the material. As its dosage increases, the residual carbon content of the composite material gradually increases, and the carbon layer gradually becomes denser and more complete, effectively suppressing the flame, making the flame smaller and shorter, and reducing the heat and harm caused by the flame, thereby improving the flame retardant performance. At the same time, silica itself can also be further filled into the gaps of the polymer material, improving the mechanical properties and corrosion resistance of the pressure-resistant, crack-resistant, and fire-resistant insulating material.

[0029] Furthermore, the phosphate flame retardant is triethyl phosphate. Triethyl phosphate has extremely low viscosity and high phosphorus content, and has good flame retardant effect.

[0030] Furthermore, the average particle size of the fumed silica is 25-35 nm, for example, the average particle size of the fumed silica is 30 nm. Nano-sized fumed silica can capture free radicals released by the combustion reaction and form a dense and uniform barrier layer, thereby enhancing the flame retardant effect.

[0031] Furthermore, the weight ratio of the fumed silica to the phosphate flame retardant is 1:(1-3), for example, the weight ratio of the fumed silica to the phosphate flame retardant is 1:2.

[0032] According to some embodiments of the present application, the cross-linking catalyst in step (1) includes at least one of organic tin and organic bismuth.

[0033] Furthermore, the cross-linking catalyst in step (1) includes at least one of dibutyltin diacetate, stannous octoate, dibutyltin dilaurate, and bismuth laurate.

[0034] In a second aspect, embodiments of the present application provide a pressure-resistant, crack-resistant, and fire-resistant cable insulation material produced by the above-mentioned method for preparing the pressure-resistant, crack-resistant, and fire-resistant cable insulation material.

[0035] A pressure-resistant, crack-resistant, and fire-resistant cable insulation material according to an embodiment of the present application has at least the following beneficial effects:

[0036] The pressure-resistant, crack-resistant and fire-resistant cable insulation material of the present application is a mixture of silane coupling agent cross-linked polypropylene with acrylonitrile-butadiene-styrene and modified polymethyl methacrylate polymer materials, which has good mechanical properties and has good pressure resistance after foaming. The addition of specific flame retardants improves the fire resistance. A composite mesh layer skeleton is built into the material and fused with the polymer material, which not only improves the mechanical strength of the pressure-resistant, crack-resistant and fire-resistant cable insulation material, but also enhances the anti-cracking performance. DETAILED DESCRIPTION

[0037] To make the purpose, technical solutions and advantages of this application more clear, the following will be further described in detail with reference to specific embodiments. The embodiments described here are only part of the embodiments of this application and should not be understood as limiting the scope of protection of this application.

[0038] Example 1

[0039] Preparation of pressure-resistant, crack-resistant and fire-resistant cable insulation materials:

[0040] (1) Sodium hydroxide and 3-aminopropyltriethoxysilane are mixed to form a pretreatment solution; basalt fiber with a diameter of 500 μm and a length of 3 cm is immersed in the pretreatment solution, and the basalt fiber is fully immersed by ultrasonic treatment to obtain pretreated basalt fiber; aramid fiber with a diameter of 600 μm and a length of 2 cm is immersed in the pretreatment solution, and the aramid fiber is fully immersed by ultrasonic treatment to obtain pretreated aramid fiber; wherein the mass ratio of aramid fiber to basalt fiber is 2.5:1.5;

[0041] (2) combing and laying the pretreated basalt fibers into a basalt fiber mesh layer, combing and laying the pretreated aramid fibers into an aramid fiber mesh layer, and then compounding the upper and lower surfaces of the basalt fiber mesh layer with a layer of aramid fiber mesh layer respectively, and using a front and back needle punching method to completely insert the aramid fibers of the aramid fiber mesh layer into the interior of the basalt fiber mesh layer to obtain a composite mesh layer skeleton;

[0042] (3) 45 parts of polymethyl methacrylate resin, 0.5 parts of dicumyl peroxide and 1.5 parts of trihydroxypropane triacrylate were mixed uniformly in a high-speed mixer, added to a torque rheometer at a speed of 60 r / min, and reacted at 165° C. for 2.5 hours to obtain a modified polymethyl methacrylate resin;

[0043] (4) 70 parts of polypropylene, 2 parts of 3-methacryloxypropyltrimethoxysilane, 32 parts of acrylonitrile-butadiene-styrene resin, 15 parts of modified polymethyl methacrylate resin, 3 parts of flame retardant, and 0.8 parts of dibutyltin diacetate were mixed uniformly according to weight to form a precursor of a composite material, and the composite material precursor was heated and plasticized at a temperature of 210° C. to reach a molten state, thereby obtaining a fully mixed molten composite material;

[0044] (5) injecting supercritical carbon dioxide into the molten composite material as a foaming agent, and uniformly mixing the foaming agent and the molten composite material through strong shearing action;

[0045] (6) placing the composite mesh layer skeleton into a mold cavity, pouring the molten composite material uniformly mixed with the foaming agent, and then foaming and molding it, placing it in a twin-screw extruder to press the tablets, and performing electron irradiation treatment through an irradiation process to fully solidify it to obtain a pressure-resistant, crack-resistant and fire-resistant cable insulation material;

[0046] The flame retardant is prepared by mixing fumed silica with an average particle size of 30 nm and triethyl phosphate in a weight ratio of 1:2.

[0047] Example 2

[0048] Preparation of pressure-resistant, crack-resistant and fire-resistant cable insulation materials:

[0049] (1) Sodium hydroxide and 3-aminopropyltriethoxysilane are mixed to form a pretreatment solution; basalt fiber with a diameter of 1000 μm and a length of 1 cm is immersed in the pretreatment solution, and the basalt fiber is fully immersed by ultrasonic treatment to obtain pretreated basalt fiber; aramid fiber with a diameter of 1000 μm and a length of 1 cm is immersed in the pretreatment solution, and the aramid fiber is fully immersed by ultrasonic treatment to obtain pretreated aramid fiber; wherein the mass ratio of aramid fiber to basalt fiber is 3:1;

[0050] (2) combing and laying the pretreated basalt fibers into a basalt fiber mesh layer, combing and laying the pretreated aramid fibers into an aramid fiber mesh layer, and then compounding the upper and lower surfaces of the basalt fiber mesh layer with a layer of aramid fiber mesh layer respectively, and using a front and back needle punching method to completely insert the aramid fibers of the aramid fiber mesh layer into the interior of the basalt fiber mesh layer to obtain a composite mesh layer skeleton;

[0051] (3) 50 parts of polymethyl methacrylate resin, 0.4 parts of dicumyl peroxide and 2 parts of trihydroxypropane triacrylate were mixed uniformly in a high-speed mixer according to weight parts, added to a torque rheometer at a speed of 50 r / min, and reacted at 170° C. for 2 h to obtain a modified polymethyl methacrylate resin;

[0052] (4) 80 parts of polypropylene, 1 part of 3-methacryloxypropyltrimethoxysilane, 40 parts of acrylonitrile-butadiene-styrene resin, 10 parts of modified polymethyl methacrylate resin, 4 parts of flame retardant and 0.5 parts of stannous octoate were mixed uniformly according to weight parts to form a precursor of a composite material, and the composite material precursor was heated and plasticized at a temperature of 230° C. to reach a molten state to obtain a fully mixed molten composite material;

[0053] (5) injecting supercritical carbon dioxide into the molten composite material as a foaming agent, and uniformly mixing the foaming agent and the molten composite material through strong shearing action;

[0054] (6) placing the composite mesh layer skeleton into a mold cavity, pouring the molten composite material uniformly mixed with the foaming agent, and then foaming and molding it, placing it in a twin-screw extruder to press the tablets, and performing electron irradiation treatment through an irradiation process to fully solidify it to obtain a pressure-resistant, crack-resistant and fire-resistant cable insulation material;

[0055] The flame retardant is prepared by mixing fumed silica with an average particle size of 25 nm and triethyl phosphate in a weight ratio of 1:3.

[0056] Example 3

[0057] Preparation of pressure-resistant, crack-resistant and fire-resistant cable insulation materials:

[0058] (1) Sodium hydroxide and 3-aminopropyltriethoxysilane are mixed to form a pretreatment solution; basalt fiber with a diameter of 10 μm and a length of 4 cm is immersed in the pretreatment solution, and the basalt fiber is fully immersed by ultrasonic treatment to obtain pretreated basalt fiber; aramid fiber with a diameter of 10 μm and a length of 4 cm is immersed in the pretreatment solution, and the aramid fiber is fully immersed by ultrasonic treatment to obtain pretreated aramid fiber; wherein the mass ratio of aramid fiber to basalt fiber is 2:2;

[0059] (2) combing and laying the pretreated basalt fibers into a basalt fiber mesh layer, combing and laying the pretreated aramid fibers into an aramid fiber mesh layer, and then compounding the upper and lower surfaces of the basalt fiber mesh layer with a layer of aramid fiber mesh layer respectively, and using a front and back needle punching method to completely insert the aramid fibers of the aramid fiber mesh layer into the interior of the basalt fiber mesh layer to obtain a composite mesh layer skeleton;

[0060] (3) 40 parts of polymethyl methacrylate resin, 0.6 parts of dicumyl peroxide and 1 part of trihydroxypropane triacrylate were mixed uniformly in a high-speed mixer according to weight parts, added to a torque rheometer at a speed of 70 r / min, and reacted at 160° C. for 3 hours to obtain a modified polymethyl methacrylate resin;

[0061] (4) uniformly mixing 60 parts of polypropylene, 3 parts of 3-methacryloxypropyltrimethoxysilane, 25 parts of acrylonitrile-butadiene-styrene resin, 20 parts of modified polymethyl methacrylate resin, 2 parts of flame retardant, and 1 part of dibutyltin dilaurate according to parts by weight to form a precursor of a composite material, and heating and plasticizing the composite material precursor at a temperature of 190° C. to achieve a molten state, thereby obtaining a fully mixed molten composite material;

[0062] (5) injecting supercritical carbon dioxide into the molten composite material as a foaming agent, and uniformly mixing the foaming agent and the molten composite material through strong shearing action;

[0063] (6) placing the composite mesh layer skeleton into a mold cavity, pouring the molten composite material uniformly mixed with the foaming agent, and then foaming and molding it, placing it in a twin-screw extruder to press the tablets, and performing electron irradiation treatment through an irradiation process to fully solidify it to obtain a pressure-resistant, crack-resistant and fire-resistant cable insulation material;

[0064] The flame retardant is prepared by mixing fumed silica with an average particle size of 35 nm and triethyl phosphate in a weight ratio of 1:1.

[0065] Example 4

[0066] Preparation of pressure-resistant, crack-resistant and fire-resistant cable insulation materials:

[0067] (1) Sodium hydroxide and 3-aminopropyltriethoxysilane are mixed to form a pretreatment solution; basalt fiber with a diameter of 400 μm and a length of 2 cm is immersed in the pretreatment solution, and the basalt fiber is fully immersed by ultrasonic treatment to obtain pretreated basalt fiber; aramid fiber with a diameter of 600 μm and a length of 3 cm is immersed in the pretreatment solution, and the aramid fiber is fully immersed by ultrasonic treatment to obtain pretreated aramid fiber; wherein the mass ratio of aramid fiber to basalt fiber is 3:2;

[0068] (2) combing and laying the pretreated basalt fibers into a basalt fiber mesh layer, combing and laying the pretreated aramid fibers into an aramid fiber mesh layer, and then compounding the upper and lower surfaces of the basalt fiber mesh layer with a layer of aramid fiber mesh layer respectively, and using a front and back needle punching method to completely insert the aramid fibers of the aramid fiber mesh layer into the interior of the basalt fiber mesh layer to obtain a composite mesh layer skeleton;

[0069] (3) 45 parts of polymethyl methacrylate resin, 0.5 parts of dicumyl peroxide and 2 parts of trihydroxypropane triacrylate were mixed uniformly in a high-speed mixer, added to a torque rheometer at a speed of 60 r / min, and reacted at 165° C. for 3 hours to obtain a modified polymethyl methacrylate resin;

[0070] (4) 70 parts of polypropylene, 2 parts of 3-methacryloxypropyltrimethoxysilane, 30 parts of acrylonitrile-butadiene-styrene resin, 15 parts of modified polymethyl methacrylate resin, 3 parts of flame retardant and 0.7 parts of bismuth laurate were mixed uniformly according to weight to form a precursor of a composite material, and the composite material precursor was heated and plasticized at a temperature of 220° C. to reach a molten state to obtain a fully mixed molten composite material;

[0071] (5) injecting supercritical carbon dioxide into the molten composite material as a foaming agent, and uniformly mixing the foaming agent and the molten composite material through strong shearing action;

[0072] (6) placing the composite mesh layer skeleton into a mold cavity, pouring the molten composite material uniformly mixed with the foaming agent, and then foaming and molding it, placing it in a twin-screw extruder to press the tablets, and performing electron irradiation treatment through an irradiation process to fully solidify it to obtain a pressure-resistant, crack-resistant and fire-resistant cable insulation material;

[0073] The flame retardant is prepared by mixing fumed silica with an average particle size of 30 nm and triethyl phosphate in a weight ratio of 1:2.

[0074] Comparative Example 1

[0075] Preparation of pressure-resistant, crack-resistant and fire-resistant cable insulation materials:

[0076] (1) Sodium hydroxide and 3-aminopropyltriethoxysilane are mixed to form a pretreatment solution; basalt fiber with a diameter of 500 μm and a length of 3 cm is immersed in the pretreatment solution, and the basalt fiber is fully immersed by ultrasonic treatment to obtain pretreated basalt fiber; aramid fiber with a diameter of 600 μm and a length of 2 cm is immersed in the pretreatment solution, and the aramid fiber is fully immersed by ultrasonic treatment to obtain pretreated aramid fiber; wherein the mass ratio of aramid fiber to basalt fiber is 2.5:1.5;

[0077] (2) combing and laying the pretreated basalt fibers into a basalt fiber mesh layer, combing and laying the pretreated aramid fibers into an aramid fiber mesh layer, and then compounding the upper and lower surfaces of the basalt fiber mesh layer with a layer of aramid fiber mesh layer respectively, and using a front and back needle punching method to completely insert the aramid fibers of the aramid fiber mesh layer into the interior of the basalt fiber mesh layer to obtain a composite mesh layer skeleton;

[0078] (3) uniformly mixing 70 parts of polypropylene, 2 parts of 3-methacryloxypropyltrimethoxysilane, 32 parts of acrylonitrile-butadiene-styrene resin, 15 parts of polymethyl methacrylate resin, 3 parts of a flame retardant, and 0.8 parts of dibutyltin diacetate according to parts by weight to form a precursor of a composite material, and heating and plasticizing the composite material precursor at a temperature of 210° C. to achieve a molten state, thereby obtaining a fully mixed molten composite material;

[0079] (4) injecting supercritical carbon dioxide into the molten composite material as a foaming agent, and uniformly mixing the foaming agent and the molten composite material through strong shearing action;

[0080] (5) placing the composite mesh layer skeleton into a mold cavity, pouring the molten composite material uniformly mixed with the foaming agent, and then foaming and molding it, placing it in a twin-screw extruder to press the tablets, and performing electron irradiation treatment through an irradiation process to fully solidify it to obtain a pressure-resistant, crack-resistant and fire-resistant cable insulation material;

[0081] The flame retardant is prepared by mixing fumed silica with an average particle size of 30 nm and triethyl phosphate in a weight ratio of 1:2.

[0082] Comparative Example 2

[0083] Preparation of pressure-resistant, crack-resistant and fire-resistant cable insulation materials:

[0084] (1) 45 parts of polymethyl methacrylate resin, 0.5 parts of dicumyl peroxide and 1.5 parts of trihydroxypropane triacrylate were mixed uniformly in a high-speed mixer, added to a torque rheometer at a speed of 60 r / min, and reacted at 165° C. for 2.5 hours to obtain a modified polymethyl methacrylate resin;

[0085] (2) 70 parts of polypropylene, 2 parts of 3-methacryloxypropyltrimethoxysilane, 32 parts of acrylonitrile-butadiene-styrene resin, 15 parts of modified polymethyl methacrylate resin, 3 parts of flame retardant and 0.8 parts of dibutyltin diacetate were mixed uniformly according to weight to form a precursor of a composite material, and the composite material precursor was heated and plasticized at a temperature of 210° C. to reach a molten state, thereby obtaining a fully mixed molten composite material;

[0086] (3) injecting supercritical carbon dioxide into the molten composite material as a foaming agent, and uniformly mixing the foaming agent and the molten composite material through strong shearing action;

[0087] (4) pouring the molten composite material uniformly mixed with the foaming agent into a mold cavity, then foaming and molding it, placing it in a twin-screw extruder for tableting, and performing electron irradiation treatment through an irradiation process to fully solidify it to obtain a pressure-resistant, crack-resistant and fire-resistant cable insulation material;

[0088] The flame retardant is prepared by mixing fumed silica with an average particle size of 30 nm and triethyl phosphate in a weight ratio of 1:2.

[0089] Comparative Example 3

[0090] Preparation of pressure-resistant, crack-resistant and fire-resistant cable insulation materials:

[0091] (1) Sodium hydroxide and 3-aminopropyltriethoxysilane are mixed to form a pretreatment solution; basalt fiber with a diameter of 500 μm and a length of 3 cm is immersed in the pretreatment solution, and the basalt fiber is fully immersed by ultrasonic treatment to obtain pretreated basalt fiber; aramid fiber with a diameter of 600 μm and a length of 2 cm is immersed in the pretreatment solution, and the aramid fiber is fully immersed by ultrasonic treatment to obtain pretreated aramid fiber; wherein the mass ratio of aramid fiber to basalt fiber is 2.5:1.5;

[0092] (2) combing and laying the pretreated basalt fibers into a basalt fiber mesh layer, combing and laying the pretreated aramid fibers into an aramid fiber mesh layer, and then compounding the upper and lower surfaces of the basalt fiber mesh layer with a layer of aramid fiber mesh layer respectively, and using a front and back needle punching method to completely insert the aramid fibers of the aramid fiber mesh layer into the interior of the basalt fiber mesh layer to obtain a composite mesh layer skeleton;

[0093] (3) 45 parts of polymethyl methacrylate resin, 0.5 parts of dicumyl peroxide and 1.5 parts of trihydroxypropane triacrylate were mixed uniformly in a high-speed mixer, added to a torque rheometer at a speed of 60 r / min, and reacted at 165° C. for 2.5 hours to obtain a modified polymethyl methacrylate resin;

[0094] (4) 70 parts of polypropylene, 2 parts of 3-methacryloxypropyltrimethoxysilane, 32 parts of acrylonitrile-butadiene-styrene resin, 15 parts of modified polymethyl methacrylate resin, 3 parts of flame retardant, and 0.8 parts of dibutyltin diacetate were mixed uniformly according to weight to form a precursor of a composite material, and the composite material precursor was heated and plasticized at a temperature of 210° C. to reach a molten state, thereby obtaining a fully mixed molten composite material;

[0095] (5) injecting supercritical carbon dioxide into the molten composite material as a foaming agent, and uniformly mixing the foaming agent and the molten composite material through strong shearing action;

[0096] (6) placing the composite mesh layer skeleton into a mold cavity, pouring the molten composite material uniformly mixed with the foaming agent, and then foaming and molding it, placing it in a twin-screw extruder to press the tablets, and performing electron irradiation treatment through an irradiation process to fully solidify it to obtain a pressure-resistant, crack-resistant and fire-resistant cable insulation material;

[0097] Wherein, the flame retardant is triethyl phosphate.

[0098] Experimental example

[0099] The pressure-resistant, crack-resistant and fire-resistant cable insulation materials prepared in Examples 1-4 and Comparative Examples 1-3 were tested for tensile strength, compressive strength, flame retardancy and corrosion resistance, respectively. The test methods are as follows:

[0100] The tensile strength is tested according to GB / T 1040-92.

[0101] The compressive strength was tested according to GB / T 8813-2008, and the compressive stress at a relative deformation of 10% was recorded.

[0102] The flame retardant grade is tested according to the standard of GB 8624-2012.

[0103] Corrosion resistance is tested in accordance with GB / T 3857-2017. If the specimen's surface gloss, color, noticeable softening or hardening, cracks, delamination, exposed fibers, or swelling remain unchanged, the corrosion resistance is recorded as Level 1 (corrosion resistant). If at least one of these conditions shows a slight change, the corrosion resistance is recorded as Level 2 (moderately corrosion resistant). If at least one of these conditions shows a significant change, the corrosion resistance is recorded as Level 3 (not corrosion resistant).

[0104] The test data is shown in Table 1 below:

[0105] Table 1

[0106]

[0107] As can be seen from Table 1, the pressure-resistant, crack-resistant and fire-resistant cable insulation materials prepared in Examples 1-4 of the present application have excellent mechanical properties such as compressive strength and tensile strength, and also have good corrosion resistance and flame retardancy.

[0108] The polymethyl methacrylate resin in the preparation raw materials of Comparative Example 1 has not been modified, and the rest are the same as Example 1. The corrosion resistance of the pressure-resistant, crack-resistant and fire-resistant cable insulation material prepared in Comparative Example 1 is significantly poor, and the compressive strength and tensile strength also decrease. This shows that in the present application, by modifying the polymethyl methacrylate resin, trimethylolpropane triacrylate can be grafted into the molecular chain structure of polymethyl methacrylate, and multiple double bonds in the same trimethylolpropane triacrylate molecule participate in the reaction, so that polymethyl methacrylate forms a cross-linked network structure, which makes the molecular weight distribution of polymethyl methacrylate wider, thereby reducing its melt flow rate, having better thermal stability and faster cleaning rate during the foaming process, being easier to process and shape, and improving the comprehensive performance of the pressure-resistant, crack-resistant and fire-resistant cable insulation material.

[0109] There is no composite mesh layer skeleton in the preparation process of Comparative Example 2, and the rest are the same as Example 1. The compressive strength and tensile strength of the pressure-resistant, crack-resistant and fire-resistant cable insulation material prepared in Comparative Example 2 are significantly reduced, indicating that the preparation method of the present application pours the molten material into the interior of the composite mesh layer skeleton and melts and bonds it, thereby enhancing the bonding effect, causing the fibers to entangle and bond with each other to form a high-strength reinforced skeleton, thereby enhancing the strength and crack resistance of the pressure-resistant, crack-resistant and fire-resistant cable insulation material.

[0110] No fumed silica was added to the raw materials for the preparation of Comparative Example 3, and the rest were the same as in Example 1. The flame retardancy of the pressure-resistant, crack-resistant, and fire-resistant cable insulation material prepared in Comparative Example 3 was significantly deteriorated, and the compressive strength and tensile strength also decreased. The corrosion resistance was also inferior to that of the pressure-resistant, crack-resistant, and fire-resistant cable insulation material in Example 1, indicating that fumed silica can not only improve the flame retardancy, but also the silica itself can further fill the gaps in the polymer material, thereby improving the mechanical properties and corrosion resistance of the pressure-resistant, crack-resistant, and fire-resistant cable insulation material.

[0111] Although the embodiments of the present application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions or variations may be made to these embodiments without departing from the principles and purpose of the present application, and that the technical solutions after these changes, modifications, substitutions or variations will fall within the scope of protection of the present application.

Claims

1. A method for preparing a pressure-resistant, crack-resistant and fire-resistant cable insulation material, characterized in that: The following steps are involved: (1) uniformly mixing 60-80 parts of polypropylene, 1-3 parts of 3-methacryloxypropyltrimethoxysilane, 25-40 parts of acrylonitrile-butadiene-styrene resin, 10-20 parts of modified polymethyl methacrylate resin, 2-4 parts of a flame retardant, and 0.5-1 part of a cross-linking catalyst according to parts by weight to form a precursor of a composite material, and heating and plasticizing the composite material precursor at a temperature of 190° C. to 230° C. to achieve a molten state, thereby obtaining a fully mixed molten composite material; (2) injecting supercritical carbon dioxide into the molten composite material as a foaming agent, and uniformly mixing the foaming agent and the molten composite material through strong shearing action; (3) placing the composite mesh layer skeleton into the mold cavity, pouring the molten composite material uniformly mixed with the foaming agent, and then foaming and molding it, placing it in a twin-screw extruder to press the sheet, and performing electron irradiation treatment through an irradiation process to fully solidify it to obtain a pressure-resistant, crack-resistant and fire-resistant cable insulation material.

2. The method for preparing a pressure-resistant, crack-resistant and fire-resistant cable insulation material according to claim 1, characterized in that: The preparation of the modified polymethyl methacrylate resin in step (1) comprises the following steps: 40-50 parts of polymethyl methacrylate resin, 0.4-0.6 parts of dicumyl peroxide and 1-2 parts of trihydroxypropane triacrylate are mixed uniformly in a high-speed mixer according to weight parts, added to a torque rheometer at a speed of 50-70 r / min, and reacted at 160-170° C. for 2-3 hours to obtain a modified polymethyl methacrylate resin.

3. The method for preparing a pressure-resistant, crack-resistant and fire-resistant cable insulation material according to claim 1, characterized in that: The preparation of the composite mesh layer skeleton in step (3) includes the following steps: combing and laying basalt fibers to form a basalt fiber mesh layer, combing and laying aramid fibers to form an aramid fiber mesh layer, and then compounding the upper and lower surfaces of the basalt fiber mesh layer with a layer of aramid fiber mesh layer respectively, and using the front and back needle punching method to completely insert the aramid fibers of the aramid fiber mesh layer into the interior of the basalt fiber mesh layer to obtain a composite mesh layer skeleton.

4. The method for preparing a pressure-resistant, crack-resistant and fire-resistant cable insulation material according to claim 3, characterized in that: The mass ratio of the aramid fiber to the basalt fiber is (2-3):(1-2).

5. The method for preparing a pressure-resistant, crack-resistant and fire-resistant cable insulation material according to claim 3, characterized in that: The basalt fiber is prepared by the following pretreatment method: sodium hydroxide and 3-aminopropyltriethoxysilane are mixed to form a pretreatment solution; the basalt fiber is immersed in the pretreatment solution, and the basalt fiber is fully immersed by ultrasonic treatment to obtain the pretreated basalt fiber; The aramid fiber is prepared by the following pretreatment method: sodium hydroxide and 3-aminopropyltriethoxysilane are mixed to form a pretreatment solution; the aramid fiber is immersed in the pretreatment solution, and the aramid fiber is fully immersed by ultrasonic treatment to obtain the pretreated aramid fiber.

6. The method for preparing a pressure-resistant, crack-resistant and fire-resistant cable insulation material according to claim 1, characterized in that: The flame retardant in step (1) is prepared by mixing a phosphate flame retardant and fumed silica.

7. The method for preparing a pressure-resistant, crack-resistant and fire-resistant cable insulation material according to claim 6, characterized in that: The average particle size of the fumed silica is 25-35 nm.

8. The method for preparing a pressure-resistant, crack-resistant and fire-resistant cable insulation material according to claim 6, characterized in that: The weight ratio of the fumed silica to the phosphate flame retardant is 1:(1-3).

9. The method for preparing a pressure-resistant, crack-resistant and fire-resistant cable insulation material according to claim 1, characterized in that: The cross-linking catalyst in step (1) includes at least one of organic tin and organic bismuth.

10. A pressure-resistant, crack-resistant, and fire-resistant cable insulation material prepared by the method for preparing a pressure-resistant, crack-resistant, and fire-resistant cable insulation material according to any one of claims 1 to 9.

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