Weather-resistant flame-retardant crosslinked polyethylene insulation material, cable material and preparation method

Abstract

The invention discloses a weather-resistant flame-retardant crosslinked polyethylene insulating material, a cable material and a preparation method. The weather-resistant flame-retardant crosslinked polyethylene insulating material comprises the following components in parts by mass: 60-70 parts of linear low-density polyethylene (LLDPE), 20-25 parts of low-density polyethylene (LDPE) and 15-20 parts of a copolymerization mixture, the copolymerization mixture is prepared from a styrene-ethylene / butylene-styrene block copolymer (SEBS) and styrene-ethylene / butylene-styrene block copolymer grafted maleic anhydride (SEBS-g-MAH). The cable material disclosed by the invention not only can give consideration to the flame-retardant characteristic and light aging resistance of a cable insulating material, but also can inhibit the damage of moisture to the insulating material under an alternating electric field, reduce the moisture entering the insulating material in a natural environment, and improve the water tree resistance of the material.

Description

Technical Field

[0001] The invention relates to the technical field of insulating materials for overhead insulated cables, and in particular to a weather-resistant and flame-retardant cross-linked polyethylene insulating material, a cable material and a preparation method thereof. Background Art

[0002] In urban power distribution systems, as the space corridors for power transmission lines become increasingly tight, the use of overhead insulated cables is becoming more and more common, and they are widely used in power transmission lines that cross forests, hills, rivers, etc. Compared with overhead bare wires, the outer layer of the conductor of overhead cables is coated with solid insulating materials, which can reduce the risk of short circuits caused by overlapping branches, reduce the salt spray corrosion phenomenon commonly found in metal conductors in coastal air, and reduce the chemical corrosion phenomenon of acids, alkalis, salts and other substances in the air of urban industrial areas, and have a broad market space.

[0003] However, overhead cables with voltage levels of 20kV and below do not have complete protective structures such as water-blocking layers, metal sheaths and outer sheaths like buried cables. According to standards such as JB / T 13795 and GB / T 14049, single-core overhead cables of 20kV and below are only composed of conductors, conductor shields and insulation layers. The insulation layer of overhead cables is directly exposed to the air in nature and is aging due to factors such as sunlight, temperature, water vapor and vibration, which will cause the insulation of overhead cables to deteriorate, fail and spontaneously combust. Its dripping materials may also ignite the vegetation under the line, thereby inducing fires.

[0004] In view of the above problems, the solutions are as follows: 1. Enhance the weather resistance of materials; 2. Enhance the flame retardancy of insulating materials. In order to enhance the weather resistance and flame retardancy of overhead cable insulating materials, patent CN116987345A adds flame retardant fillers, light stabilizers and antioxidants to high-density polypropylene to achieve flame retardancy, light aging resistance and thermal oxidation aging performance; patent CN116189989A adds solid flame retardants and liquid flame retardants to PVC for compounding to achieve flame retardancy; patent CN116178873A adds PCS / ZB composite flame retardant and carbon black to high-density polyethylene to enhance the flame retardancy and light aging resistance of insulating materials. The above patents focus on improving the flame retardancy and light aging resistance of insulating materials. However, in the long-term operation of medium-voltage overhead cables, the performance degradation of the insulation layer due to moisture absorption is more prominent, and the existing overhead cable insulating materials have not received enough attention. Patent CN116023727A is based on common low-density polyethylene, blended with maleic anhydride grafted polyethylene and ethylene-butyl acrylate copolymer to achieve the purpose of reducing water tree aging, but the material system does not take flame retardancy into consideration; in addition, the low-density polyethylene in the material system accounts for more than 90% of the insulation material, and the raw material cost is slightly higher than that of the raw material with linear low-density polyethylene (LLDPE) as the main base material, and LLDPE has a slight advantage over LDPE in dielectric properties and mechanical properties.

[0005] Therefore, there is an urgent need for a medium voltage overhead cable insulation material that is flame retardant, light resistant and water tree resistant to extend its service life in a natural environment.

[0006] In view of this, this application is hereby filed. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides a weather-resistant flame-retardant cross-linked polyethylene insulation material, a cable material and a preparation method, which can not only take into account the flame retardant properties and light aging resistance of the cable insulation material, but also inhibit the damage of moisture to the insulation material under an alternating electric field, reduce the entry of moisture into the insulation material in the natural environment, and improve the material's anti-water treeing ability.

[0008] The present invention is achieved through the following technical solutions:

[0009] In a first aspect, the present invention provides a weather-resistant flame-retardant cross-linked polyethylene insulation material for overhead use, comprising the following components by weight: 60 to 70 parts of linear low-density polyethylene (LLDPE), 20 to 25 parts of low-density polyethylene (LDPE), and 15 to 20 parts of a copolymer mixture;

[0010] The copolymer mixture includes styrene-ethylene / butylene-styrene block copolymer (SEBS) and styrene-ethylene / butylene-styrene block copolymer grafted with maleic anhydride (SEBS-g-MAH).

[0011] The polyethylene insulating base material of the invention adopts LLDPE / LDPE / SEBS+SEBS-g-MAH blending, wherein the main components are LLDPE and LDPE compounded, LLDPE has low cost, excellent dielectric properties and mechanical properties, and can improve the working performance of the insulating material, and the SEBS+SEBS-g-MAH mixture can enhance the compatibility of the entire material system, inhibit the precipitation of polar flame retardants, and improve the uniformity of the dispersion of auxiliary agents such as carbon forming agents and carbon black; at the same time, the SEBS+SEBS-g-MAH mixture is an elastomer, which can inhibit the growth of micro cracks caused by electrical stress and water diffusion pressure, thereby inhibiting the growth of water trees; the presence of styrene groups absorbs the energy of high-energy electrons, improves the dielectric strength and water tree resistance of the polyethylene insulating base material, and the anhydride hydrophilic groups can generate strong interactions with water molecules, making it difficult for water molecules to condense into droplets in the blend, so that a significant water tree resistance effect can be achieved at a relatively low weight fraction.

[0012] In a specific embodiment, the density of the linear low-density polyethylene is 0.918-0.920 g / cm 3, melt flow rate is 1.3-1.8 g / 10 min; the density of the low-density polyethylene is 0.920-0.923 g / cm3, and the melt flow rate is 2.1-2.3 g / 10 min; the density of the styrene-ethylene / butylene-styrene block copolymer is 0.908-0.910 g / cm 3 , melt flow rate: 10g / 10min.

[0013] In a specific embodiment, the styrene-ethylene / butylene-styrene block copolymer grafted with maleic anhydride (SEBS-g-MAH) is prepared by blending maleic anhydride (MAH) as a grafting monomer and dicumyl peroxide (DCP) as an initiator with styrene-ethylene / butylene-styrene block copolymer (SEBS) using a melt grafting method.

[0014] The specific preparation method is as follows:

[0015] 1) placing maleic anhydride (MAH), dicumyl peroxide (DCP) and SEBS in a drying oven for drying;

[0016] 2) 100 parts of SEBS, 2 parts of MAH and 0.15 parts of DCP were put into a high-speed mixer for blending;

[0017] 3) putting the blended raw materials into a twin-screw extruder for melt blending, the temperature of each zone of the twin-screw extruder is 170-185°C, the neck temperature is 185-195°C, the head temperature is 195-205°C; the main engine speed is 25-50r / min;

[0018] 4) The extruded material is pulled through water for cooling and then pelletized in a pelletizer to obtain SEBS-g-MAH pellets.

[0019] In a second aspect, the present invention provides a high-performance flame-retardant overhead insulated cable material, comprising the following components by weight:

[0020] 92-98 parts of material A, 4-6 parts of material B and 17-30 parts of flame retardant masterbatch;

[0021] The material A comprises 96-98 parts of polyethylene insulating base material and 2-4 parts of silane cross-linking agent; the polyethylene insulating base material is the polyethylene insulating material;

[0022] The material B comprises 100 parts of the polyethylene insulating material, 2-5 parts of an antioxidant, 3-5 parts of an anti-copper agent, 4-5 parts of a catalyst, 3-4 parts of carbon black, and 0.2-0.6 parts of an ultraviolet light absorber;

[0023] The flame retardant masterbatch comprises 40-50 parts of the polyethylene insulating material, 30-40 parts of decabromodiphenylethane, 10-20 parts of antimony trioxide and 5-10 parts of a carbon forming agent.

[0024] The insulating cable material provided by the present invention is composed of the aforementioned polyethylene insulating material as the main component, combined with a flame retardant material and a catalyst, which can inhibit the damage of moisture to the insulating material under an alternating electric field, reduce the entry of moisture into the insulating material in the natural environment, improve the material's ability to resist water treeing, and can also improve the flame retardant properties and light aging resistance of the cable insulating material.

[0025] Among them, the flame retardant masterbatch adopts a flame retardant system of decabromodiphenylethane + antimony trioxide + carbon forming agent, and a small amount of addition can meet the flame retardant requirements, and has little effect on the mechanical properties, dielectric properties and other physical and chemical properties of the composite insulating material. Decabromodiphenylethane and antimony trioxide are the main flame retardant components, and the two have a synergistic flame retardant effect, mainly based on gas phase flame retardancy, and can release non-combustible gases, annihilate free radicals and destroy the chain reaction of combustion. The flame retardant performance of the flame retardant system selected by the present invention is only related to its own dosage, and will not be affected by the insulating base material, so it can ensure the effectiveness of flame retardancy, and the combustion of decabromodiphenylethane does not produce polybrominated benzene para-dioxins and polybrominated dibenzofurans, which is environmentally friendly.

[0026] In a specific embodiment, the preparation method of the carbon-forming agent is as follows:

[0027] 1) mixing sodium montmorillonite and deionized water with mechanical stirring, heating in a water bath and stirring to obtain a montmorillonite suspension;

[0028] 2) Mix octadecyltrimethylammonium chloride and deionized water, and stir thoroughly until completely dissolved;

[0029] 3) The solution obtained in 2) is mixed with a montmorillonite suspension, heated and mechanically stirred, and the mixed suspension is then centrifuged and washed with deionized water until all the Cl is washed out, and the white precipitate is ultrasonically vibrated, dried and ground to obtain an OMMT particle carbonizing agent with an exfoliated lamellar structure.

[0030] The carbon forming agent of the flame retardant masterbatch of the present invention is organic montmorillonite, which can not only enhance the flame retardant performance, but also improve the polyethylene crystal structure, fill the structure gaps, etc., thereby reducing the intrusion of water; at the same time, its layer peeling structure can weaken the destructive effect of water on the electro-induced stress in the material, and after ultrasonic treatment, OMMT can be dispersed more evenly in the system, so that the filling effect is more excellent.

[0031] In addition, the insulating material of the present invention is used for the insulation of overhead cables, which are not crowded places, so the requirements for low smoke and halogen-free are not high; on the contrary, for the smoke that emits sufficient recognition, it can help people quickly identify the fault location of the overhead line, thereby preventing the occurrence and expansion of fires and reducing personal and property losses. Therefore, the present invention selects the above-mentioned halogen-containing flame retardant system, which can significantly reduce the impact of the flame retardant system on the performance of composite insulating materials on the one hand; on the other hand, it can reduce the cost of raw materials and has more practical value. Overhead cables are suspended in the air, away from people, and the flame retardant system has a very low impact on the environment, meets environmental protection requirements, and is very suitable for the use of overhead cables.

[0032] In a specific embodiment, the silane cross-linking agent includes 100 parts of silane, 15-25 parts of initiator, 2-5 parts of anti-scorch agent and 1-3 parts of antioxidant.

[0033] In a specific embodiment, the silane is a mixture of one or more of unsaturated silane, vinyltrimethoxysilane, vinyl(β-methoxyethoxy)silane, and vinyltriethoxysilane;

[0034] The initiator is dicumyl peroxide (DCP);

[0035] The anti-scorch agent is dibenzothiazyl disulfide (DM);

[0036] The antioxidant is a mixture of one or more of antioxidant 1010, antioxidant 168, antioxidant 300, antioxidant 1035, and antioxidant 1076.

[0037] In a specific embodiment, the anti-copper agent is N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine (MD1024), which can inhibit the degradation of heavy metal-catalyzed insulating materials;

[0038] The catalyst is dibutyltin dilaurate (DBDTL), which plays a role in increasing the rate of silane hydrolysis condensation reaction;

[0039] The carbon black is channel black with a particle size of 10 to 30 μm;

[0040] The ultraviolet absorber is UV531.

[0041] In a third aspect, the present invention provides a method for preparing a high-performance flame-retardant overhead insulated cable material, comprising the following steps:

[0042] (1) uniformly mixing linear low-density polyethylene, low-density polyethylene, styrene-ethylene / butylene-styrene block copolymer and styrene-ethylene / butylene-styrene block copolymer grafted with maleic anhydride mixture and subjecting the mixture to twin-screw granulation to obtain a polyethylene insulation base material;

[0043] (2) mixing the polyethylene insulation base material and the silane cross-linking agent uniformly and subjecting the mixture to twin-screw granulation to prepare material A;

[0044] (3) 100 parts of polyethylene insulation base material, antioxidant, anti-copper agent, catalyst, carbon black and ultraviolet light absorber are uniformly mixed and granulated by twin screw extruder to prepare material B;

[0045] (4) blending and extruding the flame retardant masterbatch according to the proportion to prepare the flame retardant masterbatch;

[0046] (5) Material A, material B and flame retardant masterbatch are mixed evenly according to a proportion and extruded through a single screw to obtain a high-performance flame retardant overhead insulating cable material.

[0047] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0048] 1. A weather-resistant flame-retardant cross-linked polyethylene insulation material, cable material and preparation method provided in an embodiment of the present invention adopts LLDPE / LDPE / SEBS+SEBS-g-MAH blending, wherein the main components are compounded with LLDPE and LDPE, LLDPE has low cost, excellent dielectric properties and mechanical properties, and can improve the working performance of the insulation material, and the mixture of SEBS+SEBS-g-MAH can enhance the compatibility of the entire material system, inhibit the precipitation of polar flame retardants, and improve the uniformity of dispersion of additives such as carbonizing agents and carbon black;

[0049] 2. A weather-resistant and flame-retardant cross-linked polyethylene insulation material, a cable material and a preparation method provided by an embodiment of the present invention, wherein the SEBS+SEBS-g-MAH mixture is an elastomer, which can inhibit the growth of microcracks caused by electrical stress and water diffusion pressure, thereby inhibiting the growth of water trees; wherein the presence of styrene groups absorbs the energy of high-energy electrons, improves the dielectric strength and water tree resistance of the polyethylene insulation base material, and the anhydride hydrophilic groups can produce strong interactions with water molecules, making it difficult for water molecules to condense into droplets in the blend, so that a significant water tree resistance effect can be achieved at a relatively low weight fraction;

[0050] 3. A weather-resistant flame-retardant cross-linked polyethylene insulation material, cable material and preparation method provided in an embodiment of the present invention adopts a flame retardant system of decabromodiphenylethane + antimony trioxide + carbon-forming agent, and a small amount of addition can meet the flame retardant requirements, and has little effect on the mechanical properties, dielectric properties and other physical and chemical properties of the composite insulation material;

[0051] 4. A weather-resistant flame-retardant cross-linked polyethylene insulation material, cable material and preparation method provided by an embodiment of the present invention, wherein decabromodiphenylethane and antimony trioxide are used as main flame-retardant components, and the two have a synergistic flame-retardant effect, mainly based on gas phase flame retardancy, and can release non-combustible gas, annihilate free radicals and destroy the chain reaction of combustion. The flame-retardant performance of the flame-retardant system selected by the present invention is only related to its own dosage and will not be affected by the insulating base material, so the effectiveness of flame retardancy can be guaranteed, and the combustion of decabromodiphenylethane does not produce polybrominated benzene para-dioxins and polybrominated dibenzofurans, and is environmentally friendly;

[0052] 5. In the embodiments of the present invention, a weather-resistant and flame-retardant cross-linked polyethylene insulation material, a cable material and a preparation method are provided. The carbon-forming agent is organic montmorillonite, which can not only enhance the flame retardant properties, but also improve the polyethylene crystal structure, fill the structural gaps, etc., thereby reducing the intrusion of water. At the same time, its layer peeling structure can weaken the destructive effect of water on the electro-induced stress in the material. After ultrasonic treatment, OMMT can be dispersed more evenly in the system, making the filling effect more excellent. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments. The illustrative embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0054] In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is apparent to those of ordinary skill in the art that these specific details do not have to be employed to practice the present invention. In other embodiments, in order to avoid confusing the present invention, well-known structures are not specifically described.

[0055] Throughout the specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "one embodiment," "an embodiment," "an example," or "an example" appearing in various places throughout the specification do not necessarily all refer to the same embodiment or example. Furthermore, particular features, structures, or characteristics may be combined in one or more embodiments or examples in any appropriate combinations and / or subcombinations.

[0056] In the description of the present invention, terms such as "front", "rear", "left", "right", "up", "down", "vertical", "horizontal", "high", "low", "inside" and "outside" to indicate directions or positional relationships are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the scope of protection of the present invention.

[0057] In a first aspect, the present invention provides a weather-resistant flame-retardant cross-linked polyethylene insulation material for overhead use, comprising the following components by weight: 60 to 70 parts of linear low-density polyethylene (LLDPE), 20 to 25 parts of low-density polyethylene (LDPE), and 15 to 20 parts of a copolymer mixture;

[0058] The copolymer mixture includes styrene-ethylene / butylene-styrene block copolymer (SEBS) and styrene-ethylene / butylene-styrene block copolymer grafted with maleic anhydride (SEBS-g-MAH).

[0059] The polyethylene insulating base material of the invention adopts LLDPE / LDPE / SEBS+SEBS-g-MAH blending, wherein the main components are LLDPE and LDPE compounded, LLDPE has low cost, excellent dielectric properties and mechanical properties, and can improve the working performance of the insulating material, and the SEBS+SEBS-g-MAH mixture can enhance the compatibility of the entire material system, inhibit the precipitation of polar flame retardants, and improve the uniformity of the dispersion of auxiliary agents such as carbon forming agents and carbon black; at the same time, the SEBS+SEBS-g-MAH mixture is an elastomer, which can inhibit the growth of micro cracks caused by electrical stress and water diffusion pressure, thereby inhibiting the growth of water trees; the presence of styrene groups absorbs the energy of high-energy electrons, improves the dielectric strength and water tree resistance of the polyethylene insulating base material, and the anhydride hydrophilic groups can generate strong interactions with water molecules, making it difficult for water molecules to condense into droplets in the blend, so that a significant water tree resistance effect can be achieved at a relatively low weight fraction.

[0060] In a specific embodiment, the density of the linear low-density polyethylene is 0.918-0.920 g / cm 3 , melt flow rate is 1.3-1.8 g / 10 min; the density of the low-density polyethylene is 0.920-0.923 g / cm3, and the melt flow rate is 2.1-2.3 g / 10 min; the density of the styrene-ethylene / butylene-styrene block copolymer is 0.908-0.910 g / cm 3 , melt flow rate: 10g / 10min.

[0061] In a specific embodiment, the styrene-ethylene / butylene-styrene block copolymer grafted with maleic anhydride (SEBS-g-MAH) is prepared by blending maleic anhydride (MAH) as a grafting monomer and dicumyl peroxide (DCP) as an initiator with styrene-ethylene / butylene-styrene block copolymer (SEBS) using a melt grafting method.

[0062] The specific preparation method is as follows:

[0063] 1) placing maleic anhydride (MAH), dicumyl peroxide (DCP) and SEBS in a drying oven for drying;

[0064] 2) 100 parts of SEBS, 2 parts of MAH and 0.15 parts of DCP were put into a high-speed mixer for blending;

[0065] 3) putting the blended raw materials into a twin-screw extruder for melt blending, the temperature of each zone of the twin-screw extruder is 170-185°C, the neck temperature is 185-195°C, the head temperature is 195-205°C; the main engine speed is 25-50r / min;

[0066] 4) The extruded material is pulled through water for cooling and then pelletized in a pelletizer to obtain SEBS-g-MAH pellets.

[0067] In a second aspect, the present invention provides a high-performance flame-retardant overhead insulated cable material, comprising the following components by weight:

[0068] 92-98 parts of material A, 4-6 parts of material B and 17-30 parts of flame retardant masterbatch;

[0069] The material A comprises 96-98 parts of polyethylene insulating base material and 2-4 parts of silane cross-linking agent; the polyethylene insulating base material is the polyethylene insulating material;

[0070] The material B comprises 100 parts of the polyethylene insulating material, 2-5 parts of an antioxidant, 3-5 parts of an anti-copper agent, 4-5 parts of a catalyst, 3-4 parts of carbon black, and 0.2-0.6 parts of an ultraviolet light absorber;

[0071] The flame retardant masterbatch comprises 40-50 parts of the polyethylene insulating material, 30-40 parts of decabromodiphenylethane, 10-20 parts of antimony trioxide and 5-10 parts of a carbon forming agent.

[0072] The insulating cable material provided by the present invention is composed of the aforementioned polyethylene insulating material as the main component, combined with a flame retardant material and a catalyst, which can inhibit the damage of moisture to the insulating material under an alternating electric field, reduce the entry of moisture into the insulating material in the natural environment, improve the material's ability to resist water treeing, and can also improve the flame retardant properties and light aging resistance of the cable insulating material.

[0073] Among them, the flame retardant masterbatch adopts a flame retardant system of decabromodiphenylethane + antimony trioxide + carbon forming agent, and a small amount of addition can meet the flame retardant requirements, and has little effect on the mechanical properties, dielectric properties and other physical and chemical properties of the composite insulating material. Decabromodiphenylethane and antimony trioxide are the main flame retardant components, and the two have a synergistic flame retardant effect, mainly based on gas phase flame retardancy, and can release non-combustible gases, annihilate free radicals and destroy the chain reaction of combustion. The flame retardant performance of the flame retardant system selected by the present invention is only related to its own dosage, and will not be affected by the insulating base material, so it can ensure the effectiveness of flame retardancy, and the combustion of decabromodiphenylethane does not produce polybrominated benzene para-dioxins and polybrominated dibenzofurans, which is environmentally friendly.

[0074] In a specific embodiment, the preparation method of the carbon-forming agent is as follows:

[0075] 1) mixing sodium montmorillonite and deionized water with mechanical stirring, heating in a water bath and stirring to obtain a montmorillonite suspension;

[0076] 2) Mix octadecyltrimethylammonium chloride and deionized water, and stir thoroughly until completely dissolved;

[0077] 3) The solution obtained in 2) is mixed with a montmorillonite suspension, heated and mechanically stirred, and the mixed suspension is then centrifuged and washed with deionized water until all the Cl is washed out, and the white precipitate is ultrasonically vibrated, dried and ground to obtain an OMMT particle carbonizing agent with an exfoliated lamellar structure.

[0078] The carbon forming agent of the flame retardant masterbatch of the present invention is organic montmorillonite, which can not only enhance the flame retardant performance, but also improve the polyethylene crystal structure, fill the structure gaps, etc., thereby reducing the intrusion of water; at the same time, its layer peeling structure can weaken the destructive effect of water on the electro-induced stress in the material, and after ultrasonic treatment, OMMT can be dispersed more evenly in the system, so that the filling effect is more excellent.

[0079] In addition, the insulating material of the present invention is used for the insulation of overhead cables, which are not crowded places, so the requirements for low smoke and halogen-free are not high; on the contrary, for the smoke that emits sufficient recognition, it can help people quickly identify the fault location of the overhead line, thereby preventing the occurrence and expansion of fires and reducing personal and property losses. Therefore, the present invention selects the above-mentioned halogen-containing flame retardant system, which can significantly reduce the impact of the flame retardant system on the performance of composite insulating materials on the one hand; on the other hand, it can reduce the cost of raw materials and has more practical value. Overhead cables are suspended in the air, away from people, and the flame retardant system has a very low impact on the environment, meets environmental protection requirements, and is very suitable for the use of overhead cables.

[0080] In a specific embodiment, the silane cross-linking agent includes 100 parts of silane, 15-25 parts of initiator, 2-5 parts of anti-scorch agent and 1-3 parts of antioxidant.

[0081] In a specific embodiment, the silane is a mixture of one or more of unsaturated silane, vinyltrimethoxysilane, vinyl(β-methoxyethoxy)silane, and vinyltriethoxysilane;

[0082] The initiator is dicumyl peroxide (DCP);

[0083] The anti-scorch agent is dibenzothiazyl disulfide (DM);

[0084] The antioxidant is a mixture of one or more of antioxidant 1010, antioxidant 168, antioxidant 300, antioxidant 1035, and antioxidant 1076.

[0085] In a specific embodiment, the anti-copper agent is N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine (MD1024), which can inhibit the degradation of heavy metal-catalyzed insulating materials;

[0086] The catalyst is dibutyltin dilaurate (DBDTL), which plays a role in increasing the rate of silane hydrolysis condensation reaction;

[0087] The carbon black is channel black with a particle size of 10 to 30 μm;

[0088] The ultraviolet absorber is UV531.

[0089] In a third aspect, the present invention provides a method for preparing a high-performance flame-retardant overhead insulated cable material, comprising the following steps:

[0090] (1) uniformly mixing linear low-density polyethylene, low-density polyethylene, styrene-ethylene / butylene-styrene block copolymer and styrene-ethylene / butylene-styrene block copolymer grafted with maleic anhydride mixture and subjecting the mixture to twin-screw granulation to obtain a polyethylene insulation base material;

[0091] (2) mixing the polyethylene insulation base material and the silane cross-linking agent uniformly and subjecting the mixture to twin-screw granulation to prepare material A;

[0092] (3) 100 parts of polyethylene insulation base material, antioxidant, anti-copper agent, catalyst, carbon black and ultraviolet light absorber are uniformly mixed and granulated by twin screw extruder to prepare material B;

[0093] (4) blending and extruding the flame retardant masterbatch according to the proportion to prepare the flame retardant masterbatch;

[0094] (5) Material A, material B and flame retardant masterbatch are mixed evenly according to a proportion and extruded through a single screw to obtain a high-performance flame retardant overhead insulating cable material.

[0095] Example 1

[0096] The embodiment of the present invention provides a weather-resistant flame-retardant cross-linked polyethylene insulated cable material for overhead use of 20 kV and below, comprising the following components in parts by weight:

[0097] 95 parts of material A, 5 parts of material B and 25 parts of flame retardant masterbatch;

[0098] The material A comprises 96-98 parts of polyethylene insulation base material and 2-4 parts of silane cross-linking agent; the polyethylene insulation base material is blended by LLDPE / LDPE / SEBS+SEBS-g-MAH, and the ratio is 70 / 20 / 20 (10+10);

[0099] The material B comprises 100 parts of polyethylene insulation base material, 4 parts of antioxidant, 3 parts of anti-copper agent, 4 parts of dibutyltin dilaurate catalyst, 3.5 parts of channel carbon black and 0.5 parts of ultraviolet light absorber;

[0100] The flame retardant masterbatch comprises 40 parts of polyethylene insulation base material, 39 parts of decabromodiphenylethane, 13 parts of antimony trioxide and 8 parts of carbon forming agent.

[0101] The 20 kV and below overhead weather-resistant flame-retardant cross-linked polyethylene insulated cable material prepared using the above raw materials in this embodiment has a vertical combustion performance grade of V-0 and an oxygen index of not less than 28%. It also has excellent weather resistance, especially outstanding water tree resistance.

[0102] Example 2

[0103] The embodiment of the present invention provides a weather-resistant and flame-retardant cross-linked polyethylene insulated cable material for overhead use of 20 kV and below, which is basically the same as Example 1, except that the weight ratio of the raw materials is different. In this embodiment, the polyethylene insulation base material is made of raw materials with the following weight ratio: the ratio of LLDPE / LDPE / SEBS+SEBS-g-MAH is: 60 / 30 / 20 (10+10).

[0104] Example 3

[0105] The embodiment of the present invention provides a weather-resistant and flame-retardant cross-linked polyethylene insulated cable material for overhead use of 20 kV and below, which is basically the same as Example 1, except that the weight ratio of the raw materials is different. In this embodiment, the polyethylene insulation base material is made of raw materials with the following weight ratio: the ratio of LLDPE / LDPE / SEBS+SEBS-g-MAH is: 60 / 20 / 20 (10+10).

[0106] Comparative Example 1

[0107] The embodiment of the present invention provides an insulating cable material, which is basically the same as Example 1, except that the weight ratio of the raw materials is different. In this comparative example, the polyethylene insulating base material is made of raw materials with the following weight ratio: LLDPE / LDPE ratio is: 20 / 70.

[0108] Comparative Example 2

[0109] The embodiment of the present invention provides a weather-resistant flame-retardant cross-linked polyethylene insulated cable material for overhead use of 20 kV and below, which is basically the same as Example 1, except that the weight ratio of the raw materials is different. In this embodiment, 100 parts of material A / material B are taken according to a 95 / 5 ratio, and 10 parts of the flame-retardant masterbatch are taken.

[0110] Comparative Example 3

[0111] The embodiment of the present invention provides a weather-resistant flame-retardant cross-linked polyethylene insulated cable material for overhead use of 20 kV and below, which is basically the same as Example 1, except that the weight ratio of the raw materials is different. In this embodiment, 100 parts of material A / material B are taken according to a 95 / 5 ratio, and 15 parts of the flame-retardant masterbatch are taken.

[0112] Example 4

[0113] The embodiment of the present invention provides a weather-resistant flame-retardant cross-linked polyethylene insulated cable material for overhead use of 20 kV and below, which is basically the same as Example 1, except that the weight ratio of the raw materials is different. In this embodiment, 100 parts of material A / material B are taken according to a 95 / 5 ratio, and 25 parts of the flame-retardant masterbatch are taken.

[0114] Comparative Example 4

[0115] The embodiment of the present invention provides a weather-resistant flame-retardant cross-linked polyethylene insulated cable material for overhead use of 20 kV and below, which is basically the same as Example 1, except that the weight ratio of the raw materials is different. In this embodiment, 100 parts of material A / material B are taken according to a 95 / 5 ratio, and 50 parts of the flame-retardant masterbatch are taken.

[0116] The insulating materials obtained in Examples 1 to 4 and Comparative Examples 1 to 4 were subjected to relevant performance tests, and the results are shown in Table 1 below.

[0117] Table 1

[0118]

[0119]

[0120] It can be seen from Examples 1 to 3 that the introduction of hydrophilic groups leads to an increase in water absorption; SEBS + SEBS-g-MAH can inhibit the growth of water trees; and it can be seen from Comparative Example 1 that the mechanical properties and anti-water tree properties of the composite material without the addition of SEBS + SEBS-g-MAH are significantly worse than those of Examples 1 to 3. It can be seen from Example 4 and Comparative Examples 2 to 4 that with the increase in the amount of flame retardant masterbatch added, the flame retardancy first increases rapidly and then increases slowly, and the addition of flame retardant masterbatch has little effect on the mechanical properties and dielectric properties of the material. However, with the excessive addition of flame retardant masterbatch in Comparative Example 4, the oxygen index improvement effect is not obvious, but instead causes a decrease in the mechanical properties of the composite material.

[0121] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A weather-resistant flame-retardant cross-linked polyethylene insulation material for overhead use, characterized in that: The invention comprises the following components by weight: 60 to 70 parts of linear low-density polyethylene (LLDPE), 20 to 25 parts of low-density polyethylene (LDPE), and 15 to 20 parts of copolymer mixture; The copolymer mixture includes styrene-ethylene / butylene-styrene block copolymer (SEBS) and styrene-ethylene / butylene-styrene block copolymer grafted with maleic anhydride (SEBS-g-MAH).

2. The weather-resistant flame-retardant cross-linked polyethylene insulation material for aerial use according to claim 1, characterized in that: The density of the linear low-density polyethylene is 0.918-0.920 g / cm 3 , melt flow rate is 1.3~1.8g / 10min; The low-density polyethylene has a density of 0.920-0.923 g / cm3 and a melt flow rate of 2.1-2.3 g / 10 min; The density of the styrene-ethylene / butylene-styrene block copolymer is 0.908-0.910 g / cm 3 , melt flow rate: 10g / 10min.

3. The weather-resistant flame-retardant cross-linked polyethylene insulation material for aerial use according to claim 1, characterized in that: The styrene-ethylene / butylene-styrene block copolymer grafted with maleic anhydride (SEBS-g-MAH) is prepared by blending maleic anhydride (MAH) as a grafting monomer and dicumyl peroxide (DCP) as an initiator with styrene-ethylene / butylene-styrene block copolymer (SEBS) using a melt grafting method.

4. The weather-resistant flame-retardant cross-linked polyethylene insulation material for aerial use according to claim 3, characterized in that: The mass ratio of styrene-ethylene / butylene-styrene block copolymer (SEBS), maleic anhydride (MAH) and diisopropylbenzene peroxide (DCP) is 100:2:0.

15.

5. A high-performance flame-retardant overhead insulated cable material, characterized in that: Includes the following mass components: 92-98 parts of material A, 4-6 parts of material B and 17-30 parts of flame retardant masterbatch; The material A comprises 96-98 parts of polyethylene insulating base material and 2-4 parts of silane cross-linking agent; the polyethylene insulating base material is any one of the polyethylene insulating materials in claims 1-4; The material B comprises 100 parts of the polyethylene insulating material according to any one of claims 1 to 4, 2 to 5 parts of an antioxidant, 3 to 5 parts of an anti-copper agent, 4 to 5 parts of a catalyst, 3 to 4 parts of carbon black, and 0.2 to 0.6 parts of an ultraviolet light absorber; The flame retardant masterbatch comprises 40-50 parts of the polyethylene insulating material according to any one of claims 1 to 4, 30-40 parts of decabromodiphenylethane, 10-20 parts of antimony trioxide and 5-10 parts of a carbon forming agent.

6. A high performance flame retardant overhead insulated cable material according to claim 5, characterized in that: The preparation method of the carbon forming agent is as follows: 1) mixing sodium montmorillonite and deionized water with mechanical stirring, heating in a water bath and stirring to obtain a montmorillonite suspension; 2) Mix octadecyltrimethylammonium chloride and deionized water, and stir thoroughly until completely dissolved; 3) The solution obtained in 2) is mixed with a montmorillonite suspension, heated and mechanically stirred, and the mixed suspension is then centrifuged and washed with deionized water until all the Cl is washed out, and the white precipitate is ultrasonically vibrated, dried and ground to obtain an OMMT particle carbonizing agent with an exfoliated lamellar structure.

7. A high performance flame retardant overhead insulated cable material according to claim 5, characterized in that: The silane cross-linking agent comprises 100 parts of silane, 15-25 parts of initiator, 2-5 parts of anti-scorch agent and 1-3 parts of antioxidant.

8. A high performance flame retardant overhead insulated cable material according to claim 7, characterized in that: The silane is a mixture of one or more of unsaturated silane, vinyltrimethoxysilane, vinyl (β-methoxyethoxy) silane, and vinyltriethoxysilane; The initiator is dicumyl peroxide (DCP); The anti-scorch agent is dibenzothiazyl disulfide (DM); The antioxidant is a mixture of one or more of antioxidant 1010, antioxidant 168, antioxidant 300, antioxidant 1035, and antioxidant 1076.

9. A high performance flame retardant overhead insulated cable material according to claim 5, characterized in that: The anti-copper agent is N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine (MD1024); The catalyst is dibutyltin dilaurate (DBDTL); The carbon black is channel black with a particle size of 10 to 30 μm; The ultraviolet absorber is UV531.

10. The method for preparing the high performance flame retardant overhead insulated cable material according to any one of claims 5 to 9, characterized in that: The steps include: (1) uniformly mixing linear low-density polyethylene, low-density polyethylene, styrene-ethylene / butylene-styrene block copolymer and styrene-ethylene / butylene-styrene block copolymer grafted with maleic anhydride mixture and subjecting the mixture to twin-screw granulation to obtain a polyethylene insulation base material; (2) mixing the polyethylene insulation base material and the silane cross-linking agent uniformly and subjecting the mixture to twin-screw granulation to prepare material A; (3) mixing polyethylene insulation base material, antioxidant, anti-copper agent, catalyst, carbon black and ultraviolet light absorber uniformly and granulating by twin screw extruder to prepare material B; (4) blending and extruding the flame retardant masterbatch according to the proportion to prepare the flame retardant masterbatch; (5) Material A, material B and flame retardant masterbatch are mixed evenly according to a proportion and extruded through a single screw to obtain a high-performance flame retardant overhead insulating cable material.

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