A cable insulation material and a method for producing the same

Abstract

The application relates to the technical field of automobile cables, and discloses a cable insulation material and a preparation method thereof.The cable insulation material provided by the application comprises, in parts by weight, the following raw materials: 20-35 parts of thermoplastic polyurethane, 40-60 parts of polydodecanamide, 0.5-2.0 parts of a compatilizer, 0.3-1.5 parts of a cross-linking curing agent, 5-15 parts of silane-modified fillers, 0.2-0.5 parts of an antioxidant, and 0.2-0.8 parts of a lubricant.The compatilizer containing double bonds, ester groups and carbonyl groups, the cross-linking curing agent and the silane-modified fillers are added to the cable insulation material, so that the heat resistance, dielectric properties, interface compatibility, hydrolysis resistance, tensile strength and elongation at break of the cable insulation material are simultaneously improved, the material has both flexibility and rigidity, the processing and use requirements of the cable, such as bending and stretching, can be met, and problems such as brittle fracture and falling-off can be avoided.

Description

Technical Field

[0001] This invention relates to the field of automotive cable technology, specifically to a cable insulation material and its preparation method. Background Technology

[0002] With the rapid development of the new energy vehicle industry, automobiles are iterating and upgrading towards higher voltage, higher power, and longer range, which places stringent requirements on the performance of automotive cables. As the core carrier for energy transmission and signal transmission in new energy vehicles, the insulation layer and sheath materials of cables must simultaneously possess excellent heat resistance, dielectric properties, hydrolysis resistance, and mechanical properties to ensure long-term stable operation of cables under high temperature, humidity, and high voltage conditions and avoid safety hazards caused by material failure.

[0003] Currently, the commonly used insulation materials for new energy vehicle cables mainly include polydodecanoic acid and thermoplastic polyurethane. Among them, polydodecanoic acid has excellent mechanical strength, chemical corrosion resistance and dimensional stability, and is one of the ideal matrix materials for cables. Thermoplastic polyurethane has good flexibility, impact resistance and wear resistance. It can be blended with polydodecanoic acid to achieve complementary performance and improve the high rigidity of polydodecanoic acid. However, the existing polydodecanoic acid and thermoplastic polyurethane blend materials have obvious technical bottlenecks and are difficult to meet the high-end requirements of new energy vehicles: (1) Polydodecanoic acid and thermoplastic polyurethane have large polarity differences and poor interfacial compatibility. After blending, phase separation and delamination are easy to occur, which leads to a decrease in the mechanical properties of the material and easy to cause problems such as brittleness and peeling; (2) The long-term service temperature of conventional blend materials is only 80℃-100℃, which cannot be adapted to the long-term high temperature environment of engine compartment above 120℃, and is prone to thermal aging and degradation; (3) In a humid environment, polyester thermoplastic polyurethane is prone to softening and hydrolysis, which leads to a decrease in the mechanical properties and dielectric properties of the material and significantly shortens the service life of the insulation material.

[0004] To address the aforementioned issues, existing technologies often employ a single modifier (such as a compatibilizer or silane coupling agent) to modify the blend system, or introduce inorganic fillers with excellent dielectric properties (such as high-purity fused silica powder or hydroxylated boron nitride) to reduce the dielectric constant and simultaneously increase the dielectric strength. However, these improvement schemes have significant shortcomings: on the one hand, a single modifier can only improve one property and cannot simultaneously improve heat resistance, dielectric properties, hydrolysis resistance, and interfacial compatibility; on the other hand, the inorganic filler surface is inert, with strong interlayer forces, making it prone to aggregation. This results in extremely poor dispersion of the inorganic phase in the organic system, which not only fails to improve dielectric properties but also disrupts the continuity of the polymer matrix, leading to poor interfacial bonding and a decline in the material's mechanical properties.

[0005] Therefore, how to prepare cable insulation materials with good mechanical properties, high temperature resistance, hydrolysis resistance, and excellent dielectric properties is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] This invention provides a cable insulation material to solve the problem that existing cable insulation materials cannot simultaneously meet the requirements of excellent mechanical properties, high temperature resistance, hydrolysis resistance, and high dielectric strength.

[0007] In a first aspect, the present invention provides a cable insulation material, wherein, by weight, the raw materials of the cable insulation material include: 20-35 parts of thermoplastic polyurethane, 40-60 parts of polydodecanoic acid, 0.5-2.0 parts of compatibilizer, 0.3-1.5 parts of crosslinking curing agent, 5-15 parts of silane-modified filler, 0.2-0.5 parts of antioxidant, and 0.2-0.8 parts of lubricant; The compatibilizer includes double bonds, ester groups, and carbonyl groups.

[0008] In one alternative embodiment, the compatibilizer includes at least one of ethylene-vinyl acetate-carbon monoxide terpolymer and ethylene-n-butyl acrylate-carbon monoxide terpolymer.

[0009] In one alternative embodiment, the crosslinking curing agent includes at least one of triglycidyl isocyanurate and 1,3-diglycidyl ester-5,5-dimethyl polymer.

[0010] In one alternative embodiment, the polydodecanoic acid has a number-average molecular weight of 15,000-25,000.

[0011] In one alternative embodiment, the thermoplastic polyurethane has a Shore hardness of 85A-95A.

[0012] In one optional embodiment, the method for preparing the silane-modified filler includes the following steps: heat-treating the filler with a silane coupling agent and hydroxyl silicone oil.

[0013] In one optional embodiment, the mass ratio of the silane coupling agent to the hydroxyl silicone oil is 3-6:0.5-1.

[0014] In one optional embodiment, the total mass of the silane coupling agent and the hydroxyl silicone oil is 2wt%-5wt% of the filler mass.

[0015] In one optional embodiment, the silane coupling agent includes at least one of γ-aminopropyltriethoxysilane and phenyltrimethoxysilane.

[0016] In one optional embodiment, the heat treatment includes: first stirring at 80℃-85℃ for 15min-25min, and then stirring at 95℃-100℃ for 20min-30min.

[0017] In an alternative implementation, a voltage stabilizer is also included.

[0018] In one alternative embodiment, the voltage stabilizer includes at least one of 2-hydroxy-4-n-octyloxybenzophenone and 2-hydroxy-4-n-heptyloxybenzophenone.

[0019] In one optional embodiment, the voltage stabilizer is present in 0.2-0.8 parts by weight.

[0020] In one optional embodiment, the thermoplastic polyurethane includes at least one of polyester-type polyurethane and polyether-type polyurethane.

[0021] In one alternative embodiment, the antioxidant comprises at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris[2,4-di-tert-butylphenyl]phosphite, 4-[(4,6-dioctylthio-1,3,5-triazin-2-yl)amino]-2,6-di-tert-butylphenol, and N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine.

[0022] In one alternative embodiment, the lubricant comprises at least one of calcium stearate, ethylene bis-stearamide, and polyethylene wax.

[0023] In one alternative embodiment, the filler includes at least one of silicon dioxide and hydroxylated boron nitride.

[0024] In a second aspect, the present invention provides a method for preparing the cable insulation material described in the first aspect, comprising the following steps: The raw materials for the cable insulation material are mixed and then extruded to obtain the cable insulation material.

[0025] In one optional embodiment, during the extrusion step, the temperature of the feeding section is 170℃-175℃, the temperature of the compression section is 185℃-190℃, the temperature of the melt reaction section is 195℃-200℃, the temperature of the homogenization section is 200℃-205℃, the temperature of the die head is 200℃-205℃, the melt pressure is 2.0MPa-2.5MPa, the residence time is 2.5min-3min, and the screw speed is 220r / min-250r / min.

[0026] The technical solution of this invention has the following advantages: 1. The cable insulation material provided by this invention, by weight, comprises the following raw materials: 20-35 parts thermoplastic polyurethane, 40-60 parts polydodecanoic acid, 0.5-2.0 parts compatibilizer, 0.3-1.5 parts crosslinking curing agent, 5-15 parts silane-modified filler, 0.2-0.5 parts antioxidant, and 0.2-0.8 parts lubricant. This invention, by adding compatibilizer, crosslinking curing agent, and silane-modified filler to the cable insulation material for crosslinking modification, simultaneously improves the heat resistance, dielectric properties, interfacial compatibility, hydrolysis resistance, tensile strength, and elongation at break of the cable insulation material. Simultaneously, the material balances flexibility and rigidity, meeting the processing and usage requirements of cable bending and stretching, and avoiding problems such as brittleness and detachment. Detailed Implementation

[0027] The following embodiments are provided to better understand the present invention, but the following embodiments do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the scope of protection of the present invention.

[0028] Unless otherwise specified, all experimental steps or conditions in the examples were performed according to conventional experimental procedures and conditions in the art. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0029] To address the aforementioned problems, in a first aspect, the present invention provides a cable insulation material, wherein, by weight, the raw materials of the cable insulation material comprise: 20-35 parts of thermoplastic polyurethane, 40-60 parts of polydodecanoic acid, 0.5-2.0 parts of compatibilizer, 0.3-1.5 parts of crosslinking curing agent, 5-15 parts of silane-modified filler, 0.2-0.5 parts of antioxidant, and 0.2-0.8 parts of lubricant; The compatibilizer includes double bonds, ester groups, and carbonyl groups.

[0030] In this invention, a compatibilizer containing double bonds, ester groups, and carbonyl groups is added. The carbonyl group in its molecular structure can undergo a nucleophilic addition reaction with the amino group of polydodecanoic acid, and the ester group can undergo an ester exchange reaction with the hydroxyl group of thermoplastic polyurethane. This effectively breaks down the interfacial barrier between polydodecanoic acid and thermoplastic polyurethane, solves the problem of blending and delamination, improves the interfacial bonding force of the composite material, and significantly enhances the stability of mechanical and dielectric properties.

[0031] In one alternative embodiment, the compatibilizer includes at least one of ethylene-vinyl acetate-carbon monoxide terpolymer and ethylene-n-butyl acrylate-carbon monoxide terpolymer.

[0032] In one alternative embodiment, the crosslinking curing agent includes at least one of triglycidyl isocyanurate and 1,3-diglycidyl ester-5,5-dimethyl polymer (hydantoin epoxy resin).

[0033] In this invention, a crosslinking curing agent is added. The epoxy groups in its molecular structure have the following effects: they react with compatibilizers, polydodecanoic acid, thermoplastic polyurethane, and silane-modified fillers to form a stable three-dimensional crosslinking network, thereby improving the interfacial bonding force between the silane-modified filler and polydodecanoic acid and thermoplastic polyurethane, thus improving the heat resistance and hydrolysis resistance of the cable insulation material, preventing yellowing of the cable insulation material, and raising the long-term service temperature of the composite material to 130℃-150℃, which is fully suitable for the high-temperature use environment of new energy vehicles.

[0034] In one alternative embodiment, the polydodecanoic acid has a number-average molecular weight of 15,000-25,000.

[0035] In one alternative embodiment, the thermoplastic polyurethane has a Shore hardness of 85A-95A.

[0036] Furthermore, the purity of the triglycidyl isocyanurate and 1,3-diglycidyl ester-5,5-dimethyl polymer is ≥99%.

[0037] In one optional embodiment, the method for preparing the silane-modified filler includes the following steps: heat-treating the filler, silane coupling agent, and hydroxyl silicone oil to obtain the filler.

[0038] In one optional embodiment, the mass ratio of the silane coupling agent to the hydroxyl silicone oil is 3-6:0.5-1.

[0039] In one optional embodiment, the total mass of the silane coupling agent and the hydroxyl silicone oil is 2wt%-5wt% of the mass of the silica.

[0040] In one optional embodiment, the silane coupling agent includes at least one of γ-aminopropyltriethoxysilane and phenyltrimethoxysilane; preferably, the silane coupling agent includes γ-aminopropyltriethoxysilane and phenyltrimethoxysilane in a mass ratio of 2-4:1-2. Inorganic filler powders are prone to agglomeration and clumping. γ-aminopropyltriethoxysilane not only solves the filler agglomeration problem but also triggers the silane grafting reaction, pre-reserving the amino group to undergo epoxy ring-opening crosslinking with the crosslinking curing agent, thus building an inorganic-organic interface bonding bridge. Phenyltrimethoxysilane introduces a benzene ring hydrophobic structure on the filler surface, reducing the filler's water absorption rate and improving the material's heat resistance and dielectric stability. Hydroxyl silicone oil can spatially isolate powder particles, inhibit secondary agglomeration, improve powder flowability and melt processability, and enhance the material's extrusion molding appearance and dimensional stability.

[0041] In this invention, silane-modified fillers are added. The filler body has advantages such as high insulation, dielectric stability, and temperature resistance. It can be uniformly dispersed in polydodecylamine and thermoplastic polyurethane, so that the electric field distribution is uniform, the breakdown path is extended, and the overall dielectric strength and volume resistivity of the insulation material are significantly improved. After silane modification, amino or hydrophobic phenyl groups and flexible siloxane chains are grafted onto the filler surface, which fundamentally solves the three major pain points of inorganic fillers: agglomeration, high water absorption, and weak interfacial bonding. It can form an integrated three-dimensional cross-linked network with cross-linking curing agents and compatibilizers. On the one hand, it eliminates the interfacial defects between the filler and the polydodecylamine and thermoplastic polyurethane matrix, blocking leakage channels. On the other hand, it blocks water molecule penetration, greatly improving the stability after heat resistance and humid heat aging.

[0042] In one optional embodiment, the heat treatment includes: first stirring at 80℃-85℃ for 15min-25min, and then stirring at 95℃-100℃ for 20min-30min; thereby ensuring that the silane coupling agent, hydroxyl silicone oil and the silanol groups on the filler surface are fully grafted together.

[0043] Furthermore, the polyester-type thermoplastic polyurethane in this invention has the following molecular structure characteristics: the main chain of the molecule has polar ester groups (-COO-), which have a strong electron-withdrawing inductive effect, enhancing the polarity of the active hydrogens on the terminal hydroxyl groups and hard secondary amino groups of the thermoplastic polyurethane, and improving its nucleophilic ability; it first undergoes ring-opening addition with the crosslinking curing agent at high temperature, further realizing the covalent bonding of the carbonyl-ester groups of the compatibilizer and the amino groups on the surface of the silane-modified filler, and crosslinking between the thermoplastic polyurethane molecular chains to construct a three-dimensional crosslinking network, thereby improving the interfacial compatibility and overall thermal stability; after crosslinking, it can improve the problem of easy hydrolysis of polyester-type thermoplastic polyurethane, thereby improving the resistance to damp heat, ensuring that the material simultaneously meets the requirements of high voltage insulation and vehicle-mounted damp heat / high temperature aging.

[0044] Furthermore, the polyether-type thermoplastic polyurethane in this invention exhibits the following molecular structure and activity characteristics: the soft segment is a polyoxyalkylene ether segment, and the ether bond is a weakly polar group with no electron-withdrawing activation effect. The terminal hydroxyl and secondary amino active hydrogens of thermoplastic polyurethane are weakly polar, resulting in lower nucleophilic reactivity than polyester thermoplastic polyurethane. The molecular chain is highly flexible, with weak hydrogen bonding, limiting its activation effect on epoxy groups. Therefore, under the same process, the crosslinking density of the system is lower, and the crosslinking network is more flexible. Consequently, the heat resistance of the crosslinked material is not as good as that of polyester thermoplastic polyurethane, but its elongation at break and low-temperature bending resistance are superior. Because polyether thermoplastic polyurethane does not contain easily hydrolyzed ester bonds, the hydrolysis resistance of the crosslinked material is worse than that of the polyester thermoplastic polyurethane system.

[0045] In an alternative implementation, a voltage stabilizer is also included.

[0046] In one optional embodiment, the voltage stabilizer comprises at least one of 2-hydroxy-4-n-octyloxybenzophenone and 2-hydroxy-4-n-heptyloxybenzophenone (CAS No. 3550-43-4). Preferably, it is 2-hydroxy-4-n-octyloxybenzophenone and 2-hydroxy-4-n-heptyloxybenzophenone in a mass ratio of 0.25-0.4:0.25-0.4.

[0047] Furthermore, the voltage stabilizer, combined with polydodecanoic acid, thermoplastic polyurethane, crosslinking curing agent, and silane-modified filler, can effectively capture high-energy electrons under a high-voltage electric field, inhibit the accumulation of space charge at the interface between the filler and the elastomer, uniformly distribute the electric field, and significantly improve the breakdown voltage and long-term electrical aging resistance of the composite material; it also has the effects of ultraviolet absorption and thermal stabilization, which can inhibit high humidity and high temperature aging.

[0048] In one optional embodiment, the voltage stabilizer is present in 0.2-0.8 parts by weight, preferably 0.4-0.6 parts by weight.

[0049] In one optional embodiment, the antioxidant comprises at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (antioxidant 1010), tris[2,4-di-tert-butylphenyl]phosphite (antioxidant 168), 4-[(4,6-dioctylthio-1,3,5-triazin-2-yl)amino]-2,6-di-tert-butylphenol (antioxidant 565), and N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine (antioxidant 1098); preferably, the antioxidant comprises antioxidant 1010 and antioxidant 168 in a mass ratio of 0.1-0.25:0.1-0.25.

[0050] In one alternative embodiment, the lubricant comprises at least one of calcium stearate, ethylene bis-stearamide (EBS), and polyethylene wax.

[0051] Furthermore, the inorganic filler includes at least one of silicon dioxide and hydroxylated boron nitride.

[0052] Furthermore, the purity of the silica is ≥99.90%, and the median particle size D is... 50 The range is 2μm-8μm.

[0053] Furthermore, the preparation method of hydroxylated boron nitride includes the following steps: placing boron nitride powder in a corundum crucible, spreading it evenly with a thickness controlled at 0.7cm-0.9cm, heating it to 500℃-600℃ at a heating rate of 3℃ / min-7℃ / min under an air atmosphere, holding it at this temperature for 1h-2h to perform hydroxyl activation treatment, and then naturally cooling it to room temperature to obtain hydroxylated boron nitride.

[0054] In a second aspect, the present invention provides a method for preparing the cable insulation material described in the first aspect, comprising the following steps: mixing the raw materials of the cable insulation material and then extruding and granulating them to obtain the cable insulation material.

[0055] In one optional embodiment, during the extrusion step, the temperature of the feeding section is 170℃-175℃, the temperature of the compression section is 185℃-190℃, the temperature of the melt reaction section is 195℃-200℃, the temperature of the homogenization section is 200℃-205℃, the die head temperature is 200℃-205℃, the melt pressure is 2.0MPa-2.5MPa, the residence time is 2.5min-3min, and the screw speed is 220r / min-250r / min.

[0056] In this invention, the polyester-type thermoplastic polyurethane was purchased from Covestro, model number Desmopan® 445; the polyether-type thermoplastic polyurethane was purchased from Covestro, model number Desmopan® 9385A; the polydodecanoic acid lactone was purchased from EMS, model number Grilamid L 25; the ethylene-vinyl acetate-carbon monoxide terpolymer was purchased from Dow Chemical, model number Elvaloy® 741; and the ethylene-n-butyl acrylate-carbon monoxide terpolymer was purchased from Dow Chemical, model number Elvaloy® HP441; 1,3-diglycidyl ester-5,5-dimethyl polymer (Hyne epoxy resin) was purchased from Hubei Xitai Chemical Co., Ltd., model MHR-154B; hydroxyl silicone oil was purchased from Anhui Bithai Materials Co., Ltd., model BTH-6; triglycidyl isocyanurate was purchased from Huangshan Huahui Technology Co., Ltd., model HT-806; ethylene bis-stearamide was purchased from Kesai Chenggong, model WAX2001; antioxidant 1010 was purchased from Tianjin Lianlong New Materials Co., Ltd.; antioxidant 168 was purchased from Tianjin Lianlong New Materials Co., Ltd.

[0057] Preparation Example 1 This preparation example provides a method for preparing silane-modified silica, comprising the following steps: Purity ≥99.90%, D 50 100 parts of 8μm silica were added to a high-speed mixer and heated to 85℃ at 800r / min. Then, 4 parts of γ-aminopropyltriethoxysilane, 1 part of phenyltrimethoxysilane and 0.5 parts of hydroxyl silicone oil were added to the high-speed mixer and stirred for 15min. The mixture was then heated to 95℃ and stirred for 20min. After cooling to room temperature, silane-modified silica was obtained.

[0058] Preparation Example 2 This preparation example provides a method for preparing silane-modified boron nitride, comprising the following steps: (1) Take 150 parts of boron nitride powder and place it in a corundum crucible. The thickness of the powder is controlled at 0.8 cm. Under air atmosphere, the temperature is raised to 550°C at a heating rate of 5°C / min and kept at the temperature for 1.5 h for hydroxyl activation treatment. Then, it is naturally cooled to room temperature to obtain hydroxylated boron nitride. (2) Add 100 parts of hydroxylated boron nitride to a high-speed mixer, heat it to 80°C at 1000 r / min, add 2 parts of γ-aminopropyltriethoxysilane, 2 parts of phenyltrimethoxysilane and 1 part of hydroxyl silicone oil to the high-speed mixer, stir for 25 min, heat it to 100°C, stir for 30 min, and cool it to room temperature to obtain silane-modified boron nitride.

[0059] Example 1 This embodiment provides a method for preparing cable insulation material, including the following steps: (1) Dry the thermoplastic polyurethane elastomer and polydodecanoic acid at 85°C for 2.5 h respectively, and set aside for later use; (2) Add 50 parts of dried polydodecanoic acid and 28 parts of dried polyester thermoplastic polyurethane elastomer to a high-speed mixer and mix at 1100 r / min for 3 min. Then add 10 parts of silane-modified silica prepared in Preparation Example 1, 1.2 parts of ethylene-n-butyl acrylate-carbon monoxide terpolymer, 0.8 parts of triglycidyl isocyanurate, 0.15 parts of antioxidant 1010, 0.15 parts of antioxidant 168 and 0.5 parts of ethylene bis-stearamide. Continue mixing at 1100 r / min for 12 min to obtain a mixture. (3) The above mixture is added to a twin-screw extruder. The temperature of the feeding section is set to 172℃, the temperature of the compression section is set to 187℃, the temperature of the melt reaction section is set to 197℃, the temperature of the homogenization section is set to 202℃, the temperature of the die head is set to 203℃, the melt pressure is set to 2.25MPa, the residence time is set to 2.5min, and the screw speed is set to 235r / min. Melt extrusion and in-situ crosslinking reaction are carried out. After water cooling at 25℃, pelletizing, and drying at 80℃ for 1.5h, cable insulation material is obtained.

[0060] Example 2 This embodiment provides a method for preparing cable insulation material, which is basically the same as the steps in Example 1, except that the polydodecanoic acid is 40 parts, the polyester thermoplastic polyurethane is 20 parts, the ethylene-n-butyl acrylate-carbon monoxide terpolymer is 0.5 parts, the triglycidyl isocyanurate is 0.3 parts, and the silane-modified silica prepared in Example 1 is 5 parts.

[0061] Example 3 This embodiment provides a method for preparing cable insulation material, which is basically the same as the steps in Example 1, except that the polydodecanoic acid is 60 parts, ethylene-n-butyl acrylate-carbon monoxide terpolymer is 2 parts, triglycidyl isocyanurate is 1.5 parts, and the silane-modified silica prepared in Example 1 is 15 parts.

[0062] Example 4 This embodiment provides a method for preparing cable insulation material, which is basically the same as the steps in Embodiment 1, except that the polydodecanoic acid is 40 parts and the polyester thermoplastic polyurethane is 35 parts.

[0063] Example 5 This embodiment provides a method for preparing cable insulation material, which is basically the same as the steps in Embodiment 1, except that the polydodecanoic acid is 60 parts and the polyester thermoplastic polyurethane is 20 parts.

[0064] Example 6 This embodiment provides a method for preparing cable insulation material, which is basically the same as the steps in Embodiment 1, except that it also includes the addition of 0.5 parts of 2-hydroxy-4-n-octyloxybenzophenone.

[0065] Example 7 This embodiment provides a method for preparing cable insulation material, which is basically the same as the steps in Embodiment 1, except that it also includes the addition of 0.5 parts of 2-hydroxy-4-n-heptoxybenzophenone.

[0066] Example 8 This embodiment provides a method for preparing cable insulation material, which is basically the same as the steps in Embodiment 1, except that it further includes the addition of 0.25 parts of 2-hydroxy-4-n-octyloxybenzophenone and 0.25 parts of 2-hydroxy-4-n-heptyloxybenzophenone.

[0067] Example 9 This embodiment provides a method for preparing cable insulation material, which is basically the same as the steps in Example 8, except that the silane-modified silicon dioxide prepared in Preparation Example 1 is replaced with the silane-modified boron nitride prepared in Preparation Example 2.

[0068] Example 10 This embodiment provides a method for preparing cable insulation material, which is basically the same as the steps in Embodiment 8, except that the ethylene-n-butyl acrylate-carbon monoxide terpolymer is replaced with the same amount of ethylene-vinyl acetate-carbon monoxide terpolymer.

[0069] Example 11 This embodiment provides a method for preparing cable insulation material, which is basically the same as the steps in Embodiment 8, except that triglycidyl isocyanurate is replaced with the same amount of hydantoin epoxy resin.

[0070] Example 12 This embodiment provides a method for preparing cable insulation material, including the following steps: (1) Dry the thermoplastic polyurethane elastomer and polydodecanoic acid at 90°C for 2 hours, and set aside for later use; (2) 60 parts of dried polydodecanoic acid, 35 parts of dried polyester thermoplastic polyurethane elastomer, 0.4 parts of 2-hydroxy-4-n-octyloxybenzophenone and 0.4 parts of 2-hydroxy-4-n-heptyloxybenzophenone were added to a high-speed mixer and mixed at 1100 r / min for 3 min. Then, 10 parts of silane-modified silica prepared in Preparation Example 1, 2 parts of ethylene-n-butyl acrylate-carbon monoxide terpolymer, 0.8 parts of hydantoin epoxy resin, 0.25 parts of antioxidant 1010, 0.25 parts of antioxidant 168 and 0.8 parts of ethylene bis-stearamide were added and mixed at 1100 r / min for 12 min to obtain a mixture. (3) The above mixture is added to a twin-screw extruder. The temperature of the feeding section is set to 175℃, the temperature of the compression section is set to 185℃, the temperature of the melt reaction section is set to 200℃, the temperature of the homogenization section is set to 200℃, the temperature of the die head is set to 205℃, the melt pressure is set to 2.5MPa, the residence time is set to 2.5min, and the screw speed is set to 250r / min. Melt extrusion and in-situ crosslinking reaction are carried out. After water cooling at 25℃, pelletizing, and drying at 80℃ for 1.5h, cable insulation material is obtained.

[0071] Example 13 This embodiment provides a method for preparing cable insulation material, including the following steps: (1) Dry the thermoplastic polyurethane elastomer and polydodecanoic acid at 80°C for 3 hours, and set aside for later use; (2) Add 40 parts of dried polydodecanoic acid, 20 parts of dried polyester thermoplastic polyurethane elastomer, 0.1 parts of 2-hydroxy-4-n-octyloxybenzophenone and 0.1 parts of 2-hydroxy-4-n-heptyloxybenzophenone to a high-speed mixer and mix at 1100 r / min for 3 min. Then add 10 parts of silane-modified silica prepared in Preparation Example 1, 0.5 parts of ethylene-n-butyl acrylate-carbon monoxide terpolymer, 0.3 parts of hydantoin epoxy resin, 0.1 parts of antioxidant 1010, 0.1 parts of antioxidant 168 and 0.2 parts of ethylene bis-stearamide, and continue mixing at 1100 r / min for 12 min to obtain a mixture. (3) The above mixture is added to a twin-screw extruder. The temperature of the feeding section is set to 170℃, the temperature of the compression section is set to 190℃, the temperature of the melt reaction section is set to 195℃, the temperature of the homogenization section is set to 205℃, the temperature of the die head is set to 200℃, the melt pressure is set to 2.0MPa, the residence time is set to 3min, and the screw speed is set to 220r / min. Melt extrusion and in-situ crosslinking reaction are carried out. After water cooling at 25℃, pelletizing, and drying at 80℃ for 1.5h, cable insulation material is obtained.

[0072] Example 14 This embodiment provides a method for preparing cable insulation material, which is basically the same as the steps in Embodiment 1, except that the polyester thermoplastic polyurethane is replaced with the same amount of polyether thermoplastic polyurethane.

[0073] Comparative Example 1 This embodiment provides a method for preparing cable insulation material, which is basically the same as the steps in Embodiment 1, except that the ethylene-n-butyl acrylate-carbon monoxide terpolymer is replaced with the same amount of polyester thermoplastic polyurethane.

[0074] Comparative Example 2 This embodiment provides a method for preparing cable insulation material, which is basically the same as the steps in Embodiment 1, except that triglycidyl isocyanurate is replaced with the same amount of polyester thermoplastic polyurethane.

[0075] Comparative Example 3 This embodiment provides a method for preparing cable insulation material, which is basically the same as the steps in Example 1, except that the silane-modified silica prepared in Example 1 is replaced with the same amount of polyester thermoplastic polyurethane.

[0076] Comparative Example 4 This embodiment provides a method for preparing cable insulation material, which is basically the same as the steps in Example 1, except that the silane-modified silicon dioxide prepared in Example 1 is replaced with unmodified silicon dioxide.

[0077] Experimental Example The cable insulation materials prepared in Examples 1-14 and Comparative Examples 1-4 were tested for tensile strength, elongation at break, dielectric strength, and volume resistivity at room temperature. The results are shown in Table 1.

[0078] The cable insulation materials prepared in Examples 1-14 and Comparative Examples 1-4 were placed in an environment of 85°C and 85% relative humidity for 1000 hours. Tensile strength, elongation at break, dielectric strength, and volume resistivity were then tested. The tensile strength retention rate and elongation at break retention rate were calculated. The results are shown in Table 2.

[0079] The cable insulation materials prepared in Examples 1-14 and Comparative Examples 1-4 were placed at 175°C for 240 hours, and then tensile strength, elongation at break, dielectric strength, and volume resistivity were tested. The tensile strength retention rate and elongation at break retention rate were calculated, and the results are shown in Table 3.

[0080] Tensile strength: Refer to the test method in GB / T 528-2009; Elongation at break: Refer to the test method in GB / T 528-2009; Dielectric strength: Refer to the test method in GB / T 1408.1-2016; Volume resistivity: Refer to the test method in GB / T 31838.2-2019; Tensile strength retention rate (%) = Tensile strength after aging / Tensile strength before aging × 100; Elongation at break retention rate (%) = Elongation at break after aging / Elongation at break before aging × 100.

[0081] Table 1. Test results of room temperature performance of cable insulation materials in various embodiments and comparative examples.

[0082] Table 2 Performance test results of cable insulation materials in each embodiment and comparative example after 85°C, 85%RH, and 1000h.

[0083] Table 3 Performance test results of cable insulation materials in each embodiment and comparative example after 175°C and 240h.

[0084] As can be seen from Tables 1-3, the cable insulation materials prepared in Examples 1-14 of this invention possess excellent tensile properties, dielectric strength, resistance to damp heat, and high-temperature resistance. The material properties of polyester-type polyurethane and polyether-type polyurethane differ as follows: the polyester-type polyurethane system cable insulation material exhibits superior heat resistance and higher tensile strength; the polyether-type polyurethane system cable insulation material exhibits superior resistance to damp heat and higher elongation at break. In Comparative Example 1, the compatibilizer was omitted. The large differences in polarity and crystallinity between polydodecylamide and polyester thermoplastic polyurethane resulted in numerous interface defects and easy delamination during direct blending, leading to poor tensile properties, dielectric strength, heat resistance, and high-temperature resistance of the material. The hydrolysis performance was poor. In Comparative Example 2, the addition of the crosslinking curing agent was omitted, and the polyester thermoplastic polyurethane could not undergo etherification crosslinking, failing to form a three-dimensional network structure. As a result, the various properties of the material decreased. The polyester thermoplastic polyurethane would severely absorb water and undergo hydrolysis during the humid heat aging process, leading to a decrease in performance. In Comparative Example 3, the addition of the silane-modified filler was omitted, and the dielectric strength of the material was significantly lower. In Comparative Example 4, the silane-modified silica prepared in Preparation Example 1 was replaced with unmodified silica. The unmodified SiO2 surface had a large number of Si-OH atoms, which were highly polar and severely agglomerated. At the same time, the flexible siloxane chains that improve toughness were not formed, resulting in low tensile properties, heat resistance, and humid heat resistance of the material.

[0085] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A cable insulation material, characterized in that, By weight, the raw materials of the cable insulation material include: 20-35 parts of thermoplastic polyurethane, 40-60 parts of polydodecanoic acid, 0.5-2.0 parts of compatibilizer, 0.3-1.5 parts of crosslinking curing agent, 5-15 parts of silane-modified filler, 0.2-0.5 parts of antioxidant, and 0.2-0.8 parts of lubricant; The compatibilizer includes double bonds, ester groups, and carbonyl groups.

2. The cable insulation material according to claim 1, characterized in that, The compatibilizer includes at least one of ethylene-vinyl acetate-carbon monoxide terpolymer and ethylene-n-butyl acrylate-carbon monoxide terpolymer.

3. The cable insulation material according to claim 1, characterized in that, The crosslinking curing agent includes at least one of triglycidyl isocyanurate and 1,3-diglycidyl ester-5,5-dimethyl polymer.

4. The cable insulation material according to claim 1, characterized in that, The number-average molecular weight of the polydodecanoic acid is 15,000-25,000; And / or, the Shore hardness of the thermoplastic polyurethane is 85A-95A.

5. The cable insulation material according to claim 1, characterized in that, The preparation method of the silane-modified filler includes the following steps: heat-treating the filler with a silane coupling agent and hydroxyl silicone oil.

6. The cable insulation material according to claim 5, characterized in that, The mass ratio of the silane coupling agent to the hydroxyl silicone oil is 3-6:0.5-1; And / or, the total mass of the silane coupling agent and the hydroxyl silicone oil is 2wt%-5wt% of the mass of the filler; And / or, the silane coupling agent includes at least one of γ-aminopropyltriethoxysilane and phenyltrimethoxysilane; And / or, the heat treatment includes: stirring at 80℃-85℃ for 15min-25min, and then stirring at 95℃-100℃ for 20min-30min.

7. The cable insulation material according to any one of claims 1-6, characterized in that, This also includes the addition of voltage stabilizers; Optionally, the voltage stabilizer includes at least one of 2-hydroxy-4-n-octyloxybenzophenone and 2-hydroxy-4-n-heptyloxybenzophenone; Optionally, the voltage stabilizer is present in 0.2-0.8 parts by weight.

8. The cable insulation material according to claim 1, 5, or 6, characterized in that, The thermoplastic polyurethane includes at least one of polyester-type polyurethane and polyether-type polyurethane; And / or, the antioxidant comprises at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris[2,4-di-tert-butylphenyl]phosphite, 4-[(4,6-dioctylthio-1,3,5-triazin-2-yl)amino]-2,6-di-tert-butylphenol, and N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine; And / or, the lubricant includes at least one of calcium stearate, ethylene bis-stearamide, and polyethylene wax; And / or, the filler includes at least one of silicon dioxide and hydroxylated boron nitride.

9. A method for preparing the cable insulation material according to any one of claims 1-8, characterized in that, Includes the following steps: The raw materials for the cable insulation material are mixed and then extruded to obtain the cable insulation material.

10. The method for preparing cable insulation material according to claim 9, characterized in that, In the extrusion step, the temperature of the feeding section is 170℃-175℃, the temperature of the compression section is 185℃-190℃, the temperature of the melt reaction section is 195℃-200℃, the temperature of the homogenization section is 200℃-205℃, the temperature of the die head is 200℃-205℃, the melt pressure is 2.0MPa-2.5MPa, the residence time is 2.5min-3min, and the screw speed is 220r / min-250r / min.

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