Thermoplastic allyl resin composition and preparation method thereof, shielding material and cable

Abstract

The invention provides a thermoplastic propenyl resin composition and a preparation method thereof, a shielding material and a cable, the thermoplastic propenyl resin composition comprises a propylene heterophase copolymer and a styrene elastomer, the content of the styrene elastomer is 40-60 wt%; the composition of the propylene heterophase copolymer satisfies the following conditions: TGIC grading results: (T40-T30%) / 10 = 3-4 DEG C / % and (T80%-T50%) / 30 = 0.2-0.3 DEG C / %; the styrene elastomer comprises one or more of a linear triblock copolymer with a general formula of S-R-S and a linear diblock copolymer with a general formula of S-R, S represents a styrene block, and R represents a conjugated diene block; in the styrene elastomer, the weight ratio of S to R is (25-35): (75-65). The product provided by the invention shows high breakdown strength, low space charge characteristic, low conductivity and excellent water tree resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to a thermoplastic propylene-based resin composition and a preparation method thereof, a shielding material and a cable, and belongs to the technical field of cables. BACKGROUND

[0002] Traditional overhead line transmission is limited by environment and large land occupation, and it is difficult to meet the demand of urban power distribution, so power cable transmission has replaced overhead line transmission in more and more fields. At present, extruded insulation cables represented by cross-linked polyethylene (XLPE) cables are widely used in power transmission of various voltage levels. As an important part of power grid architecture, the environmental compatibility, disposal and recycling of cables after retirement have higher requirements. XLPE is a thermosetting material, which can only be buried or incinerated after retirement, causing adverse effects on the environment and being inconsistent with the concept of sustainable development. Therefore, the development of new environmentally friendly cables to replace XLPE cables has become the focus of attention and research. Using thermoplastic polypropylene material as the insulation layer material of the cable is an important development direction of new cables, which can realize recycling after the end of product life, simplify the process flow and thus reduce energy consumption and greenhouse gas emissions in the cable manufacturing process. The demand for green and sustainable economic development promotes the change of the insulation layer material of power cables to low-carbon, environmentally friendly and recyclable thermoplastic polypropylene materials. Polypropylene insulation materials have excellent insulation performance, do not need to be cross-linked, can be recycled, and have excellent insulation and heat resistance comparable to cross-linked polyethylene.

[0003] Cross-sea power transmission technology is an important way to realize cross-sea power grid interconnection, offshore energy development and long-distance transmission. Compared with mature overhead lines and power transformation technologies, power transmission lines are still the weak link of cross-sea power transmission. According to the carrier, cross-sea power transmission can be divided into four ways: submarine cable, cross-sea bridge cable, submarine tunnel cable and cross-sea overhead line. Among them, cross-sea bridge cable and submarine tunnel cable must have a bridge or tunnel as a carrier, otherwise a special carrier for power transmission must be built, which greatly reduces the economy; cross-sea overhead line usually requires shallow water or island conditions, and is usually suitable for offshore power transmission; while the application range of submarine cable is wide, and it does not need to build a special bridge or tunnel, and can support the demand of large-scale offshore energy transmission.

[0004] When cables are used underwater, lead alloy is usually used as a metal sheath layer to cover the cable, which has radial water-blocking ability to protect the cable from water ingress and moisture caused problems. This structure is called dry cable design. Although it plays a role in water-blocking and corrosion prevention, it significantly increases the raw material cost of the cable and the installation cost is also high. In addition, there is also a wet cable structure which does not set up a metal sheath layer. The wet cable structure reduces the production process, reduces the consumption of raw materials, makes the cable body more lightweight, and at the same time improves the recyclability of the cable. However, water or moisture can migrate to the inside of the cable, thereby shortening the service life of the cable. Due to the existence of unevenness, defects and impurities in the insulation material, water or moisture will generate water tree structure in the insulation material under the action of electric field, which causes local damage to the insulation material and increases the possibility of electrical breakdown. Especially the growth of water trees can trigger the generation of electrical trees, which can eventually lead to partial discharge breakdown. Therefore, in the wet cable, the insulation layer material must have excellent water tree resistance characteristics.

[0005] The submarine cable is exposed to corrosive seawater, which may contain magnesium, calcium, potassium and sulfate ions in addition to sodium chloride. These dissolved salts in seawater have a direct impact on the formation of water trees in the cable. Therefore, the requirements for the electrical and mechanical properties of the insulation material in a saltwater environment are increased.

[0006] WO2013110893A1 discloses a medium-high voltage cable comprising an elongated electrical conductor surrounded by a non-crosslinked layer of grafted polymer material, said grafted polymer material being obtained from a polymer composition comprising at least one polyolefin and a compound intended to be grafted onto the polyolefin, the compound intended to be grafted being a grafting compound comprising at least one epoxy group and a single reactive functional group capable of grafting onto the polyolefin. This technology provides a cable comprising at least one non-crosslinked polymer layer, intended for use in the field of medium voltage power cables or high voltage power cables, with significantly improved breakdown resistance after aging, especially in a humid environment, in the presence of a direct or alternating electric field (typically greater than 25 kV / mm), which conditions are generally conducive to the formation of charged species. Although this technology improves the water tree resistance of the insulation material by introducing an epoxy group, there is no support for the improved electrical effect in any description and specific examples, and the by-products generated by the side reactions such as degradation and crosslinking are unavoidable in the grafting method, whether it is direct beta radiation grafting or grafting through a coupling agent, and these by-products have a great damage to the long-term insulation performance of the cable.

[0007] CN116444727A discloses an anti-water tree modified propylene-based thermoplastic insulating material and its preparation method and application. The thermoplastic insulating material contains a propylene polymer grafted with an oxygen-containing polar monomer and an optional second monomer, a propylene polymer, an auxiliary agent, and an optional elastomer. In the thermoplastic insulating material, the content of the oxygen-containing polar monomer and the optional second monomer in the grafted state is 0.1-6wt%, the content of xylene-soluble matter is 0-70wt%, and the gel content is less than 2wt%. The melt flow rate of the thermoplastic insulating material under a load of 2.16kg at 230℃ is 0.2-7g / 10min. The bending modulus of the thermoplastic insulating material is 150-1600MPa. This technology can effectively improve the anti-water tree performance of the insulating material by selecting a propylene polymer grafted with an oxygen-containing polar monomer and an optional second monomer as the raw material. In addition, heat treatment after product forming can further improve the anti-water tree performance of the insulating material, which is suitable for long-term use under high temperature and high field strength. Although this technology considers inhibiting side reactions such as degradation, the grafting efficiency is low, and the polar monomer may not be completely reacted and remains in the polymer, which may damage the insulation performance of the cable during long-term operation. Moreover, the subsequent long-time annealing treatment of the granules seriously affects the production efficiency. The anti-water tree performance test only focuses on the control of the water tree initiation time, ignoring the control of the water tree growth and the conversion of water tree to electrical tree.

[0008] US20200251251A1 provides a cable comprising at least one polymer layer, which is obtained from a polymer composition comprising at least one polypropylene-based thermoplastic polymer material and at least one oxygen-containing compound having a melting temperature of about 110°C or higher. The cable provided by this technology has improved aging resistance in the presence of an electric field in a humid environment and at the same time can guarantee good mechanical properties. Due to the presence of the oxygen-containing compound having a melting temperature of about 110°C or higher in the polypropylene-based polymer layer of the cable, the aging resistance of the cable in the presence of an electric field in a humid environment is significantly improved, preferably while guaranteeing that the cable has good mechanical properties. However, the polarity gap between the oxygen-containing compound and polypropylene used in this technology is large, and dispersion problems caused by aggregation of polar groups are prone to occur, thereby affecting the anti-water tree effect.

[0009] Therefore, it has become a technical problem to be solved in the art to provide a novel thermoplastic propylene-based resin composition and its preparation method, shielding material and cable. SUMMARY

[0010] In order to solve the above-mentioned shortcomings and deficiencies, the purpose of the present application is to provide a thermoplastic propylene-based resin composition and its preparation method, shielding material and cable.

[0011] To achieve the above object, in one aspect, the present application provides a thermoplastic propylene-based resin composition, wherein the thermoplastic propylene-based resin composition comprises a propylene heterophasic copolymer and a styrene-based elastomer, the content of the styrene-based elastomer is 40-60 wt%, preferably 45-55 wt%, based on the total weight of the thermoplastic propylene-based resin composition;

[0012] wherein the matrix phase of the propylene heterophasic copolymer comprises a propylene homopolymer or a propylene copolymer, and the elastomer phase comprises a propylene-α-olefin copolymer, the composition of the propylene heterophasic copolymer satisfies the conditions of (T40%-T30%) / 10=3-4℃ / % and (T80%-T50%) / 30=0.2-0.3℃ / % according to TGIC classification results;

[0013] the styrene-based elastomer comprises one or more of linear triblock copolymers of the general formula S-R-S and linear diblock copolymers of the general formula S-R, wherein S represents a styrene block and R represents a conjugated diene block; and the weight ratio of S to R in the styrene-based elastomer is 25-35:75-65.

[0014] The present application does not make specific requirements on the content of the propylene heterophasic copolymer in the thermoplastic propylene-based resin composition, and the content can be reasonably determined according to the content of the styrene-based elastomer or the total content of the styrene-based elastomer and additives, as long as the total weight of the components is 100%.

[0015] In the thermoplastic propylene-based resin composition provided by the present application, the appropriate content of the styrene-based elastomer can improve the insulation performance and ensure the good compatibility of the styrene-based elastomer and the matrix resin, i.e. the propylene heterophasic copolymer. Further, the styrene group has a higher electron affinity energy, which can induce the generation of deep trap energy levels, thereby inhibiting the initiation and growth of water trees. Since the polymerization reaction of the styrene group is generated in the main chain, the potential crosslinking and degradation reactions caused by the grafting of the polar groups contained in the possible trace impurities in the system to the main chain through free radical reactions can be avoided.

[0016] By using the styrene-based elastomer with a specific structure and utilizing the microphase separation characteristics of the styrene-based elastomer block copolymer, the styrene group aggregates can be uniformly dispersed in the system, so that the electric stress cracks can be inhibited, and the effect of inhibiting the diffusion of water trees can be achieved.

[0017] The thermoplastic propylene-based resin composition provided by the present application has a relatively high content of styrene block, i.e. the weight ratio of S to R is 25-35:75-65, which ensures that the styrene elastomer has a high number of physical entanglement points of styrene microdomains, and in combination with the high molecular weight of the styrene elastomer, i.e. Mw≥200000 g / mol, a strong chain entanglement network can be formed, thereby improving the water treeing resistance of the material.

[0018] As a specific embodiment of the thermoplastic propylene-based resin composition described above, the propylene-based resin composition comprises ≥50 wt%, preferably 55-70 wt% of the matrix phase and the balance of the elastomer phase, based on the total weight of the propylene-based resin composition.

[0019] A polymer is a long chain formed by repeating units (monomers) through chemical bonding. Unlike low molecular weight compounds, a polymer does not have a fixed molecular weight, but is a mixed system formed by homologues of different molecular weights. Therefore, the molecular weight of a polymer is an average value, which has the concept of distribution.

[0020] The chain length is usually expressed in terms of the molecular weight of the polymer chain, which is related to the relative molecular weight of the monomer and the number of monomers in the chain. However, all synthetic polymers have polydispersity, containing polymer chains of different lengths, so the molecular weight of a polymer is not a single value, but a range of polymer chain lengths and molecular weights. Therefore, the molecular weight of a polymer must be described by calculating the average of the molecular weights of all polymer chains in the sample.

[0021] wherein Mw is the weight average molecular weight. In relation to the number average molecular weight Mn, the contribution of the size of the single chain molecular weight to Mw is also taken into account when determining the average molecular weight. The greater the mass of the chain, the greater the contribution to Mw.

[0022] Mz is the Z average molecular weight, which is a kind of average molecular weight, and its calculation formula is Mz = Σ (Ni × Mi 3 ) / ΣNi × Mi 2 , wherein Ni refers to the number of polymer molecules with a molecular weight of Mi in the sample.

[0023] Mz+1 is the Z+1 average molecular weight, and its calculation formula is Mz+1 = Σ (Ni × Mi 4 ) / ΣNi × Mi 3 .

[0024] As a specific embodiment of the thermoplastic propylene-based resin composition described above, the proportion of components with a molecular weight less than 7000 g / mol is less than 2 wt%, preferably less than 1 wt%, and Mz / Mw≥5, Mz+1 / Mz≥3.5, preferably Mz / Mw≥5.5, Mz+1 / Mz≥4, based on the total weight of the matrix phase being 100%.

[0025] wherein the low molecular weight component is less, in particular having a molecular weight below the entanglement molecular weight (7000 g / mol for polypropylene), and the high molecular weight component is more, which can reduce the presence of non-entangled low molecular weight component, increase the entanglement degree of the macromolecular component and increase the possibility of forming tie molecules, thereby playing a role in delaying the growth of water trees.

[0026] As a specific embodiment of the above-mentioned thermoplastic propylene-based resin composition of the present application, wherein the propylene copolymer comprises propylene-α-olefin copolymer and / or propylene-ethylene copolymer, preferably propylene-ethylene copolymer; the content of α-olefin structural units and / or ethylene structural units is 2-7 wt%, preferably 3-5 wt%, based on the total weight of the propylene copolymer being 100%. Wherein the propylene-α-olefin copolymer can be obtained by polymerization of propylene and α-olefin, the α-olefin includes one or a combination of 1-butene, 1-hexene and 1-octene, etc.

[0027] As a specific embodiment of the above-mentioned thermoplastic propylene-based resin composition of the present application, wherein the content of α-olefin structural units is ≥ 50 wt%, preferably ≤ 70 wt% and ≥ 55 wt%, based on the total weight of the propylene-α-olefin copolymer used as the elastic phase being 100%. Wherein the propylene-α-olefin copolymer can be obtained by polymerization of propylene and α-olefin, the α-olefin is one or a combination of C4-C8 olefins, preferably one or a combination of 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene and 1-octene, more preferably 1-butene, i.e. the propylene-α-olefin copolymer used as the elastic phase is more preferably propylene-1-butene copolymer.

[0028] In the present application, when the composition of the propylene heterophasic copolymer satisfies: (T40%-T30%) / 10=3-4 ℃ / % and (T80%-T50%) / 30=0.2-0.3 ℃ / %, the electrical breakdown resistance, water tree resistance and low space charge properties of the thermoplastic propylene-based resin composition and the cable insulation layer material made therefrom can be significantly improved.

[0029] Thermal Gradient Interaction Chromatography (TGIC) is a chromatographic technique based on temperature gradient. TGIC is mainly used for component analysis of special polyolefin resins such as propylene heterophasic copolymer, polyolefin elastomer, olefin block copolymer, etc. TGIC technology can realize the separation and quantitative analysis of different components in the insulation material by adjusting the temperature gradient, thereby evaluating the performance of the insulation material.

[0030] Thermal gradient interaction chromatography (TGIC) utilizes the combined effect of adsorption-desorption and crystallization properties of polyolefin chains with TGIC column to realize the separation and characterization of different components of polyolefin under certain solvent flow rate and temperature change conditions. In particular, the non-crystalline part which cannot be analyzed by some crystallization fractionation techniques can be analyzed by means of TGIC.

[0031] The present application can ensure the regular arrangement and uniform distribution of crystallization by controlling the structure of propylene heterophasic copolymer, and also realize the control of molecular chain length and its distribution, which is beneficial to the formation of physical entanglement network of amorphous region and connection between crystalline region and tie molecule lamella. The present application can not only improve the water tree growth resistance and water tree expansion resistance of the material, but also improve the electrical breakdown resistance of the material.

[0032] In thermal gradient interaction chromatography (TGIC):

[0033] The parameter "(T40%-T30%) / 10" represents the difference between the first 30% and the first 40% of the elution component content divided by 10, which is used to calculate the slope of the peak. When the value exceeds 4.0℃ / %, the low melting temperature component is too high, which will affect the heat resistance and breakdown strength at high temperature of the material, and when the value is lower than 3.0℃ / %, it will affect the compatibility of the elastomer and the crystalline phase, causing the decline of water tree resistance.

[0034] Specifically, "T30%" represents the time or position of the first 30% of the peak, and "T40%" represents the time or position of the first 40% of the peak. By calculating the difference between the two positions and dividing by 10, the slope of the peak can be obtained. The slope of the peak can be used to analyze the shape and steepness of the peak. A larger slope indicates a more steep change in the peak, while a smaller slope indicates a more gradual change in the peak. The larger the slope value, the more steep the change in the peak.

[0035] The parameter "(T80%-T50%) / 30" represents the difference between the first 50% and the first 80% of the peak divided by 30, which is also used to calculate the slope of the peak. The denominator of this parameter is 30, indicating that the width range of the peak selected for calculating the slope of the peak is between the first 50% and the first 80% of the peak. When the value exceeds 0.3℃ / %, the stereoregularity defect of the crystallization is more, which will affect the breakdown strength of the material, and when the value is lower than 0.2℃ / %, the high stereoregularity component increases, which will cause a significant decline in the softness of the material.

[0036] Specifically, "T50%" represents the time or position of the 50% position of the peak, and T80% represents the time or position of the 80% position of the peak. By calculating the difference between the two positions and dividing by 30, the slope of the peak can be obtained. The slope of the peak can be used to analyze the shape and steepness of the peak. A larger slope indicates that the change of the peak is more steep, and a smaller slope indicates that the change of the peak is more gentle. The larger the value of the slope, the more steep the change of the peak.

[0037] As a specific embodiment of the thermoplastic propylene-based resin composition described above in the present application, when the styrene-based elastomer comprises both linear triblock copolymer (triblock) of general formula S-R-S and linear diblock copolymer (diblock) of general formula S-R, the content of linear diblock copolymer of general formula S-R, i.e. the diblock content, is 2-10 wt%, preferably 4-8 wt%, based on the total weight of the styrene-based elastomer. In the present application, the linear diblock copolymer of general formula S-R can improve the tensile strength and extrusion flowability of the thermoplastic propylene-based resin composition and the cable insulation layer made therefrom.

[0038] In the thermoplastic propylene-based resin composition described above in the present application, the conjugated diene in the conjugated diene block can be reasonably selected as needed. For example, in some embodiments of the present application, the conjugated diene can be 1,3-butadiene or isoprene, etc.

[0039] As a specific embodiment of the thermoplastic propylene-based resin composition described above in the present application, in the styrene-based elastomer, the conjugated diene block is a hydrogenated block.

[0040] As a specific embodiment of the thermoplastic propylene-based resin composition described above in the present application, when the conjugated diene block is a hydrogenated butadiene block, the ratio of the molar content of ethylene structural units to the molar content of butylene structural units is 1.5-4:1, preferably 2-3:1. By controlling the ratio of the molar content of ethylene structural units to the molar content of butylene structural units to be 1.5-4:1, the present application can improve the compatibility of the styrene-based elastomer and the propylene heterophasic copolymer.

[0041] As a specific embodiment of the thermoplastic propylene-based resin composition described above in the present application, the Mw of the styrene-based elastomer is ≥200000 g / mol, preferably ≥220000 g / mol.

[0042] As a specific embodiment of the above-mentioned thermoplastic propylene-based resin composition of the present application, the styrene-based elastomer can be a commercial product, including but not limited to products with trade names of G1650, G1651, G1652, G1654, G1657, G1633, G1641, MD6944 and MD6917 from Kraton Polymers; products with trade names of 4055, 4055, 4077 and 4099 from Kuraray; products with trade names of H1221, H1041, H1051, H1043, H1053, N505, N504 from Asahi; products with trade names of 3150, 3151, 3152, 3154 from TSRC. Compositions containing elastomers of at least two of the above-mentioned products can also be used.

[0043] In the present application, by adjusting the content of each structural unit contained in the matrix phase, the elastomer phase and the styrene-based elastomer in the thermoplastic propylene-based resin composition, the comprehensive performance of the composition can be further improved.

[0044] As a specific embodiment of the above-mentioned thermoplastic propylene-based resin composition of the present application, the thermoplastic propylene-based resin composition further comprises an additive, which comprises one or a combination of several of an antioxidant, a voltage stabilizer, a processing aid and a nucleating agent.

[0045] As a specific embodiment of the above-mentioned thermoplastic propylene-based resin composition of the present application, the content of the antioxidant is 0.01-1 wt%, preferably 0.1-0.5 wt%, the content of the voltage stabilizer is 0.01-5 wt%, preferably 0.1-2 wt% and the content of the nucleating agent is 0.01-5 wt%, preferably 0.1-1 wt%, based on the total weight of the thermoplastic propylene-based resin composition being 100%.

[0046] In the present application, the antioxidant can play a role in improving the long-term stability of the material. As a specific embodiment of the above-mentioned thermoplastic propylene-based resin composition of the present application, the antioxidant includes one or more of tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]pentaerythritol ester, tris(2,4-di-tert-butylphenyl)phosphite, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, N,N-bis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine, 3,3-thiodipropionic acid octadecyl ester, and β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid n-octadecyl ester.

[0047] In the present application, the voltage stabilizer can play a role in further improving the electrical breakdown resistance and dielectric strength of the material. As a specific embodiment of the above-mentioned thermoplastic propylene-based resin composition of the present application, the voltage stabilizer includes substituted benzophenone and / or benzil derivatives, wherein the substituents in the substituted benzophenone can be alkyl, aryl, alkoxy, and aryloxy, etc., and the benzil derivatives include one or more of 4-methoxybenzil, 4-hydroxybenzil, 4,4'-bis(dioctylamino)benzil, 4,4'-dioctylaminobenzil, p-anisil, 4,4'-dihydroxybenzil, 4,4'-di(dodecyloxy)benzil, and 4,4'-di(undec-10-enyloxy)benzil, 4-hydroxybenzil, 4-dodecyloxybenzil, and 4-undec-10-enyloxybenzil.

[0048] In the present application, the nucleating agent can play a role in reducing the grain size in the crystalline phase and further improving the electrical breakdown resistance and dielectric strength of the material. As a specific embodiment of the above-mentioned thermoplastic propylene-based resin composition of the present application, the nucleating agent includes carboxylate nucleating agent and / or phosphate nucleating agent. Among them, the carboxylate nucleating agent includes one or both of sodium benzoate and p-tert-butyl benzoic acid hydroxy aluminum; the phosphate nucleating agent includes one or both of 2,2'-methylene-bis(4,6-di-tert-butylphenyl) sodium phosphate and bis[2,2'-methylene-bis(4,6-di-tert-butylphenyl)] aluminum phosphate.

[0049] As a specific embodiment of the above-mentioned thermoplastic propylene-based resin composition of the present application, the ESCR of the thermoplastic propylene-based resin composition obtained according to GB / T 1842-2008 is ≥750h, preferably ≥800h, and more preferably ≥1000h; and the FNCT of the thermoplastic propylene-based resin composition is ≥35h, preferably ≥40h, and more preferably ≥60h, under the conditions of a temperature of 80℃ and a pressure of 4.0MPa.

[0050] Both the ESCR and the FNCT are parameters used to evaluate the environmental stress cracking resistance of a resin material, and specifically, the time for a resin material to withstand a corrosive liquid under mechanical stress (such as internal pressure, thermal stress, etc.). The environmental stress cracking refers to the premature cracking and embrittlement of a plastic (resin material) due to the simultaneous action of stress and strain and contact with a specific chemical environment.

[0051] The thermoplastic propylene-based resin composition provided by the present application not only has high environmental stress cracking resistance, but also has high resistance to water tree growth and expansion.

[0052] In another aspect, the present application also provides a preparation method of the above-mentioned thermoplastic propylene-based resin composition, wherein the preparation method comprises:

[0053] The propylene multi-phase copolymer and the styrene-based elastomer are uniformly mixed, and the uniformly mixed material is placed into a twin-screw extruder for extrusion to obtain the thermoplastic propylene-based resin composition.

[0054] As a specific embodiment of the above-mentioned preparation method of the present application, the screw temperature of the twin-screw extruder is set to 180-230℃, and the feeding screw rotation speed is 50-200r / min.

[0055] As a specific embodiment of the above-mentioned preparation method of the present application, the preparation method of the propylene multi-phase copolymer comprises:

[0056] The catalyst system is pre-contacted and then continuously introduced into a first polymerization reactor to complete a first-stage polymerization reaction, and then propylene is introduced into the first polymerization reactor and hydrogen and another olefin-based comonomer are introduced to perform a second-stage polymerization reaction to obtain a propylene copolymer; or a propylene homopolymer is prepared in the first polymerization reactor by using a conventional method;

[0057] The product obtained from the first polymerization reactor is introduced into a second polymerization reactor, and propylene and an α-olefin are introduced into the second polymerization reactor to perform a third-stage polymerization reaction, and the reaction product obtained from the second polymerization reactor is subjected to inactivation and drying treatment to obtain a propylene copolymer or a propylene multi-phase copolymer formed by a propylene homopolymer and a propylene-α-olefin copolymer.

[0058] In the preparation method of the propylene heterogeneous copolymer, the catalyst system comprises a main catalyst, a cocatalyst and an external electron donor, wherein the main catalyst comprises a Ziegler-Natta catalyst, a metallocene catalyst, an organic metal catalyst or a coordination catalyst, the cocatalyst comprises an organic aluminum, and the external electron donor comprises an organic silicon compound.

[0059] In the preparation method of the propylene heterogeneous copolymer, the main catalyst such as the Ziegler-Natta catalyst, the metallocene catalyst, the organic metal catalyst or the coordination catalyst is a conventional substance, which can be selected as required, and can be obtained by commercial purchase or by using a conventional method.

[0060] The organic aluminum as the cocatalyst comprises one or a combination of several of trialkylaluminum (such as trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, trihexylaluminum and trioctylaluminum), monochlorodiethylaluminum, monochlorodiisobutylaluminum, dichloroethylaluminum and dichloroethylaluminum.

[0061] The organic silicon compound as the external electron donor comprises one or a combination of several of isobutyltriethoxysilane, diisopropyldimethoxysilane, cyclohexylmethyldimethoxysilane, tetramethoxysilane, tetraethoxysilane, trimethylmethoxysilane, trimethylethoxysilane, trimethylphenoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, methyl-tert-butyldimethoxysilane, methylisopropyldimethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, (1,1,1-trifluoro-2-propyl)-2-ethylpiperidyl dimethoxysilane and (1,1,1-trifluoro-2-propyl)-methyldimethoxysilane.

[0062] In the preparation method of the propylene heterogeneous copolymer, the molar ratio of the organic aluminum as the cocatalyst to the organic silicon compound as the external electron donor is 1:1-200:1, preferably 10:1-50:1, in terms of aluminum / silicon.

[0063] In the preparation method of the propylene heterogeneous copolymer, the polymerization temperature of the first-stage polymerization reaction, the second-stage polymerization reaction and the third-stage polymerization reaction is generally 40-100°C, preferably 60-100°C, and the residence time of each stage of the polymerization reaction is in the range of 30 min-10 h.

[0064] The first polymerization reaction (including the first stage polymerization reaction and the second stage polymerization reaction) in the preparation method of the propylene heterogeneous copolymer described above can be carried out in a liquid phase, and the second polymerization reaction (i.e. the third stage polymerization reaction) can be carried out in a gas phase; or both the first polymerization reaction and the second polymerization reaction can be carried out in a gas phase. When the polymerization reaction is carried out in a liquid phase, the polymerization pressure is preferably in the range of 3.0-4.5 MPa. When the polymerization reaction is carried out in a gas phase, the polymerization temperature is preferably 60-90°C, and the polymerization pressure is preferably 1.0-3.0 MPa. When the polymerization reaction is carried out in a gas phase, the gas phase reactor used can be a gas phase fluidized bed, a gas phase moving bed or a gas phase stirred bed reactor, etc.

[0065] In the present application, when the thermoplastic propylene-based resin composition further comprises an additive, the preparation method thereof comprises:

[0066] The propylene heterogeneous copolymer, the styrene-based elastomer and the additive are mixed uniformly, and then the uniformly mixed material is placed into a twin-screw extruder for extrusion to obtain the thermoplastic propylene-based resin composition.

[0067] and / or,

[0068] The preparation method of the thermoplastic propylene-based resin composition described above in the present application comprises: first preparing a propylene heterogeneous copolymer according to the preparation method described above, and mixing the polymer powder obtained after the reaction material from the second polymerization reactor is inactivated and dried with an additive, melt-extruding and granulating to obtain a mixture of the propylene heterogeneous copolymer and the additive; mixing the mixture with a styrene-based elastomer uniformly, and then placing the uniformly mixed material into a twin-screw extruder for extrusion to obtain the thermoplastic propylene-based resin composition. That is, in the present application, the additive can be added in step (1), or can be added when the propylene heterogeneous copolymer is prepared, or can be added at the same time in two steps.

[0069] The mixing uniformly in the preparation method of the thermoplastic propylene-based resin composition described above in the present application can be carried out in a high-speed mixer. In some specific embodiments of the present application, the mixing is carried out at a rotational speed of 50-200 r / min and at room temperature for 3-15 min to realize the uniform mixing of the propylene heterogeneous copolymer and the styrene-based elastomer.

[0070] The preparation method of the thermoplastic propylene-based resin composition described above in the present application further comprises, after the extrusion, sequentially carrying out water cooling, traction, drying and crushing on the extruded blend to obtain the thermoplastic propylene-based resin composition.

[0071] In another aspect, the present application also provides a shielding material, wherein the shielding material comprises the thermoplastic propylene-based resin composition described above.

[0072] In still another aspect, the present application also provides a cable comprising at least one cable core, preferably at least three cable cores, the cable core comprising a conductor and, in order, an inner semiconductive shielding layer, an insulation layer and an outer semiconductive shielding layer, wherein the insulation layer is made of the shielding material as described above, and the inner semiconductive shielding layer and / or the outer semiconductive shielding layer is made of the thermoplastic propylene-based resin composition as described above.

[0073] As a specific embodiment of the above-mentioned cable of the present application, the conductor is made of metal or the like.

[0074] As a specific embodiment of the above-mentioned cable of the present application, the cable is a submarine cable, preferably a wet-structure submarine cable.

[0075] The submarine cable provided by the present application can be used at various voltage levels, preferably for transmitting electric power at a voltage higher than 35 kV.

[0076] The present application does not make specific requirements on the manufacturing method of the cable, for example, the inner semiconductive shielding layer, the insulation layer and the outer semiconductive shielding layer can be co-extruded on the conductor by an extruder using corresponding raw materials.

[0077] In summary, the thermoplastic propylene-based resin composition provided by the present application and the cable insulation layer comprising the same exhibit high breakdown strength, low space charge characteristics, low electrical conductivity, and also have excellent water treeing resistance, solving the problem of insufficient water treeing resistance of the existing wet-structure submarine cable insulation material. DETAILED DESCRIPTION

[0078] It should be noted that the terms "comprise" and any variations thereof in the specification and claims of the present application are intended to cover non-exclusive inclusion, for example, a process, method, system, product or apparatus that comprises a list of steps or units need not be limited to those clearly listed, but can include other steps or units that are not clearly listed or inherent to such processes, methods, products or apparatus.

[0079] The ranges disclosed herein are meant to include both endpoints and any range between the endpoints. For example, the ranges of "60-120" and "80-110" are intended to include at least the endpoints 60 and 120, and 80 and 110, respectively, but also to include the ranges 60-110 and 80-120, respectively. Similarly, the ranges of "1-3" and "1-5" are intended to include at least the endpoints 1 and 3, and 1 and 5, respectively, but also to include the ranges 1-5 and 1-3, respectively.

[0080] In the present application, unless otherwise stated, the numerical range "a-b" means a shorthand notation for the inclusion of any integer within the range between a and b, wherein a and b are both real numbers. For example, the numerical range "0-5" means that all the integers between "0-5" have been listed in the present application, and "0-5" is just a shorthand notation for these numerical combinations.

[0081] In the present application, unless otherwise stated, all the embodiments and preferred embodiments mentioned in the present application can be combined with each other to form new technical solutions.

[0082] In the present application, unless otherwise stated, all the technical features and preferred features mentioned in the present application can be combined with each other to form new technical solutions.

[0083] In the present application, unless otherwise stated, "multiple", "a plurality of", "a plurality of" and the like in "multiple" represent a numerical value of 2 or more. Unless otherwise stated, "%" represents mass percentage; the content ratio is also measured by mass. The meaning of "may" includes both performing a certain treatment and not performing a certain treatment. "Optional" or "optionally" means that the event or circumstance described next can occur or can not occur, and the description includes the case where the event occurs and the case where the event does not occur.

[0084] In the present application, unless otherwise stated, all the steps mentioned in the present application can be performed in sequence or randomly, but preferably in sequence. For example, the method comprises steps (a) and (b), which means that the method can comprise steps (a) and (b) performed in sequence, or steps (b) and (a) performed in sequence. For example, the method also comprises step (c), which means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0085] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in combination with the accompanying drawings and examples. The examples described below are part of the examples of the present application, but not all the examples, and are only used to illustrate the present application, and should not be regarded as limiting the scope of the present application. Based on the examples in the present application, all other examples obtained by those skilled in the art without creative labor fall within the scope of protection of the present application. If the specific conditions are not specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are used. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be purchased on the market.

[0086] Analytical test method:

[0087] Molecular weight and distribution: The molecular weight distribution (MWD) in the present application can be represented as Mz / Mw and Mz+1 / Mz. The molecular weight and molecular weight distribution of the sample are tested by high temperature gel permeation chromatography (GPC) equipped with an Agilent PLgel MIXED-B chromatographic column in the present application. The sample to be tested is dissolved in 1,2,4-trichlorobenzene with a concentration of 1.0 mg / mL, and the test temperature is 150°C, and the solution flow rate is 1.0 mL / min. The molecular weight of polystyrene is used as an internal reference to prepare a standard curve, and the molecular weight and molecular weight distribution of the sample to be tested are calculated according to the elution time.

[0088] Thermal gradient interactive chromatography (TGIC): The crystallization elution fractionation (CEF) device of the Spanish Polymer Char company is used, which is equipped with an IR-5 infrared detector, and the chromatographic column is replaced with a Hypercarb porous graphite column (100x 4.6mm, 5μm), and the mobile phase is o-dichlorobenzene. The main parameters during the test include: cooling rate (CR), cooling process flow rate (FC), heating rate (HR), elution rate (FE), injection volume, cooling temperature (TC), and the test conditions are as follows: CR=20℃ / min; FC=0mL / min; HR=2℃ / min; FE=0.5mL / min; injection volume is 200μL; TC=40℃; after the test, the differential weight curve and the integral cumulative weight curve are obtained, and then the parameters involved in the present application are obtained according to the integral cumulative weight curve.

[0089] AC breakdown strength: The test is carried out in accordance with the standard IEC60243. The power frequency AC breakdown experiment is carried out by using HJC-100kV type computer controlled voltage breakdown tester, the ball-ball electrode is used in the experiment, the material is brass, the electrode diameter is 20mm, the experimental environment is room temperature, the whole experiment process is carried out in transformer oil, and the voltage rising rate is set as 2kV / s.

[0090] Volume resistivity: The volume resistivity of the sample to be measured is measured according to the national standard GB / T 3048.3-2007 using a four-electrode system at different temperatures (e.g. 30°C and 90°C).

[0091] Space charge characteristics: The space charge of the sample to be measured is measured according to the principle of the electro-acoustic pulse method (PEA) at different temperatures (e.g. 30°C and 90°C). During the test, the pulse power is 0-600V, the pulse width is 8ns, and the space charge resolution is 1 μm. A field strength of 50kV / mm is applied for 40min, short-circuited for 10min, and the space charge distortion rate ψ inside the sample to be measured is recorded.

[0092] Environmental stress cracking resistance (ESCR): The sample to be measured is tested according to GB / T 1842-2008, and the test conditions are given in condition B of Table 1 of GB / T 1842-2008.

[0093] Full-notch creep test (FNCT): The full-notch creep test is performed according to ISO 16770 at a stress of 4.0MPa and a temperature of 80°C. Specifically, the sample used for the FNCT test is a cuboid with a size of 10x10x100mm, which is obtained by grinding a plate with a thickness of 15mm; a notch with a depth of 1.5mm is formed on four sides of the sample, a stress of 4.0MPa is applied to the sample in a 10wt% Igepal solution at 80°C, and then the time taken until the sample breaks is measured.

[0094] Salt solution aging test:

[0095] Water treeing characteristics:

[0096] A sample of the cable to be measured with a length of about 50cm is taken, and the outer semiconductive shielding layer about 10cm long is stripped at both ends; the area of the outer semiconductive shielding layer in the middle of the sample to be measured is uniformly and vertically pierced with a steel needle at an interval of 0.5cm and a depth of about 3mm; a heat shrink tube is sleeved and shrunk at both ends as a container to store saturated NaCl solution; finally, the water treeing aging experiment is performed on the sample to be measured, and during the experiment, the voltage is set to a sinusoidal high voltage with a root mean square value of 7.5kV and a frequency of 400Hz, and the water treeing aging experiment is accelerated at room temperature, and during the aging process, the saturated NaCl solution is periodically supplemented into the cavity of the heat shrink tube until the sample to be measured is broken down due to water treeing bridging of the insulation.

[0097] After the cable sample to be tested is aged for a certain time, one cable in the experimental group is randomly selected, the cable insulation layer around the pinhole is cut into a slice with a thickness of about 100 μm, and the slice is immersed in a methylene blue solution to keep dyeing at 90°C for 0.5 h; after the slice is sufficiently dyed, the outer surface thereof is wiped clean, and the slice is placed under a microscope to observe the water tree morphology and count the water tree length and width. In the present application, the slice samples of unaged samples and samples aged for 30, 60 and 90 days are placed under a microscope for observation.

[0098] Electric breakdown resistance:

[0099] The cable core of the cable sample to be tested is aged in a water tank heated to 70°C, the NaCl content in the water is 3 wt%, and after aging for 90 days, the cable core is taken out, cut into six test samples each with an effective length of 1 meter, and subjected to breakdown strength test.

[0100] Examples 1-19, denoted as EX1-EX19

[0101] Examples 1-19 of the present application provide a series of submarine cables, which are prepared by a preparation method comprising the following specific steps:

[0102] I. Preparation of main catalyst:

[0103] The reaction kettle with a stirrer is replaced with nitrogen, 2000 mL of ethanol, 60 mL of 2-ethylhexanol and 40 mL of isopropyl alcohol are added to the reaction kettle, and 2 g of magnesium chloride is added to dissolve it; after stirring, the temperature is raised, and then 30 g of magnesium powder is added gradually; the reaction is carried out until completion. After the reaction is completed, washing, separation and drying are performed to obtain a dialkyl magnesium carrier.

[0104] The dialkyl magnesium carrier and 500 mL of toluene and 5 mL of di-n-butyl phthalate are prepared into a suspension; in a reaction kettle replaced with nitrogen, 600 mL of toluene and 820 mL of titanium tetrachloride are added, the temperature is lowered to -5°C, then the suspension is added to the reaction kettle, the temperature is kept constant for 1.5 hours, then the temperature is slowly raised, when the temperature rises to 80°C, 5 mL of di-n-butyl phthalate is added, the temperature is continuously slowly raised to 105°C, the temperature is kept constant for 1.5 hours, then the liquid is filtered clean; then a mixed liquid composed of 550 mL of toluene and 750 mL of titanium tetrachloride is added and the temperature is raised to 105°C for stirring for 1 hour, the liquid is filtered off, the obtained solid is washed with hexane for 3 times, the liquid is filtered off and dried to obtain the main catalyst.

[0105] II. Preparation of propylene heterogeneous copolymer, which is prepared according to the formula shown in Table 1, and the preparation process is carried out on a polypropylene device, which mainly includes a first loop reactor and a second gas phase reactor:

[0106] The main catalyst, co-catalyst (triethyl aluminum) and external electron donor (isobutyl triethoxysilane) prepared in I. are pre-contacted at 10°C for 30 minutes and then continuously introduced into the first loop reactor to complete the first stage polymerization reaction. The temperature of the first stage polymerization reaction in the first loop reactor is 70°C, and the reaction pressure is 4.0 MPa. Liquid propylene is added to the first loop reactor, and a certain amount of hydrogen and ethylene are introduced at the same time. The material is allowed to stay in the first loop reactor (temperature 70°C, pressure 4.0 MPa) for 1 hour to obtain a propylene-ethylene copolymer.

[0107] The product obtained from the first loop reactor is introduced into the second gas phase reactor, and propylene and 1-butene are introduced into the second gas phase reactor to continue the copolymerization reaction. The copolymerization reaction temperature is 75°C, the reaction pressure is 1.5 MPa, and the material stays in the reactor for 3 hours.

[0108] The reaction product obtained from the second gas phase reactor is dried by wet nitrogen to remove unreacted catalyst and heated to obtain a polymer powder. The polymer powder is mixed with pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] according to the content of antioxidant, which accounts for 0.2% of the total weight of the thermoplastic propylene-based resin composition, and is melt extruded and granulated to obtain a mixture of propylene heterophasic copolymer and antioxidant.

[0109] III. Preparation of thermoplastic propylene-based resin composition:

[0110] The mixture of propylene heterophasic copolymer and antioxidant prepared above, and styrene-based elastomer are weighed and placed in a high-speed mixer, mixed at a speed of 130 r / min at room temperature for 10 min. The uniformly mixed material is placed in a twin-screw extruder, and the screw temperature of the twin-screw extruder is set to 200°C, and the feeding screw speed is set to 140 r / min for extrusion. The extruded blend is water-cooled, pulled, dried, and broken to obtain an insulation layer resin composition, i.e. a thermoplastic propylene-based resin composition.

[0111] IV. Preparation of submarine cable:

[0112] 50 wt% of the above insulation layer resin composition, 20 wt% of vinyl acetate and 30 wt% of acetylene black are mixed in a high-speed mixer at a speed of 100 r / min at room temperature for 10 min. The uniformly mixed material is placed in a twin-screw extruder, and the screw temperature of the twin-screw extruder is set to 200°C, and the feeding screw speed is set to 140 r / min for extrusion. The extruded blend is water-cooled, pulled, dried, and broken to obtain a shielding material.

[0113] A copper alloy conductor core wire having a diameter of 14 mm was stranded to form a conductor; then, a shielding material for making an inner semiconductive shielding layer, an insulating layer resin composition, and a shielding material for making an outer semiconductive shielding layer were respectively fed into extruders A-C; the respective extrudates from the extruders A-C were guided to a co-extrusion die, and the inner semiconductive shielding layer, the insulating layer, and the outer semiconductive shielding layer were simultaneously extruded from the inside to the outside of the conductor's outer periphery, and the thicknesses of the inner semiconductive shielding layer, the insulating layer, and the outer semiconductive shielding layer were respectively set to 1 mm, 4 mm, and 1 mm. Thus, a submarine cable having a conductor layer, an inner semiconductive shielding layer, an insulating layer, and an outer semiconductive shielding layer from the center to the outer periphery was manufactured.

[0114] Table 1

[0115]

[0116] Comparative Examples 1-6, denoted as CX1-CX6, respectively

[0117] To more clearly show the effects of the present application, the inventors weighed each component according to the proportions listed in Table 2, and prepared the products of Comparative Examples 1-6 in the same manner as in Examples 1-19.

[0118] Table 2

[0119]

[0120] The volume resistivity, AC breakdown strength, space charge distortion rate, water tree length, water tree width, ESCR, and FNCT of the products obtained in Examples 1-19 and Comparative Examples 1-6 were respectively tested according to the analysis test methods provided above, and the results are shown in Tables 3 and 4, respectively.

[0121] Table 3

[0122]

[0123]

[0124] Table 4

[0125]

[0126] From the experimental data in Table 3 above, it can be seen that the products provided in Examples 1-19 exhibit excellent performance in multiple properties, such as volume resistivity and space charge distortion rate at 30°C, volume resistivity and space charge distortion rate at 90°C, AC breakdown strength before and after aging, water tree length and width at different aging days, ESCR, and FNCT.

[0127] In comparison, by comparing the experimental data in Table 3 and Table 4, it can be seen that, compared with the product provided by Example 1 of the present application, the products provided by Comparative Examples 1-6 are poor in volume resistivity and space charge distortion rate at 30℃, volume resistivity and space charge distortion rate at 90℃, AC breakdown strength before and after aging, water tree length and width at different aging days, ESCR and FNCT and other performances.

[0128] In summary, the thermoplastic propylene-based resin composition provided by the example of the present application and the cable insulation layer comprising the same exhibit high breakdown strength, low space charge characteristics, low conductivity, and also have excellent water tree resistance, solving the problem of insufficient water tree resistance of existing wet structure submarine cable insulation materials.

[0129] The above is only a specific embodiment of the present application, which cannot limit the scope of the application. Therefore, the replacement of equivalent components or equivalent changes and modifications made within the scope of the present application should still fall within the scope of the present patent. In addition, the technical features in the present application can be freely combined with each other, between technical features, between technical features and technical inventions, and between technical inventions.

Claims

1. A thermoplastic acrylic resin composition, characterized in that, The thermoplastic propylene-based resin composition comprises a propylene multiphase copolymer and a styrene elastomer, wherein the styrene elastomer content is 40-60 wt% based on 100% of the total weight of the thermoplastic propylene-based resin composition; The matrix phase of the propylene multiphase copolymer includes propylene homopolymer or propylene copolymer, and the elastic phase includes propylene-α-olefin copolymer. The composition of the propylene multiphase copolymer satisfies the following TGIC classification results: (T40%-T30%) / 10 = 3-4℃ / % and (T80%-T50%) / 30 = 0.2-0.3℃ / %. The styrene-based elastomers include one or more of linear triblock copolymers with the general formula SRS and linear diblock copolymers with the general formula SR, wherein S represents a styrene block and R represents a conjugated diene block; in the styrene-based elastomers, the weight ratio of S to R is 25-35:75-65.

2. The thermoplastic acrylic resin composition according to claim 1, characterized in that, The propylene multiphase copolymer comprises ≥50 wt% of a matrix phase and the balance being an elastic phase, based on a total weight of 100%.

3. The thermoplastic acrylic resin composition according to claim 1, characterized in that, Based on the total weight of the matrix phase as 100%, the proportion of components with a molecular weight of less than 7000 g / mol is less than 2 wt% and Mz / Mw≥5, Mz+1 / Mz≥3.

5.

4. The thermoplastic acrylic resin composition according to claim 1, characterized in that, The propylene copolymer includes propylene-α-olefin copolymer and / or propylene-ethylene copolymer, and the content of α-olefin structural units and / or ethylene structural units is 2-7 wt% based on 100% of the total weight of the propylene copolymer.

5. The thermoplastic acrylic resin composition according to claim 1, characterized in that, Based on the total weight of the propylene-α-olefin copolymer as 100%, the content of α-olefin structural units is ≥50wt%.

6. The thermoplastic acrylic resin composition according to claim 1, characterized in that, The content of the linear diblock copolymer of general formula SR is 2-10 wt%, based on 100% of the total weight of the styrene elastomer.

7. The thermoplastic acrylic resin composition according to claim 1 or 6, characterized in that, In the styrene-based elastomer, the conjugated diene block is a hydrogenated block.

8. The thermoplastic acrylic resin composition according to claim 7, characterized in that, When the conjugated diene block is a hydrogenated butadiene block, the molar ratio of the ethylene structural unit to the butene structural unit is 1.5-4:

1.

9. The thermoplastic acrylic resin composition according to claim 1 or 6, characterized in that, The styrene-based elastomer has a Mw ≥ 200000 g / mol.

10. The thermoplastic acrylic resin composition according to claim 1, characterized in that, The thermoplastic propylene-based resin composition further comprises additives, which include one or a combination of antioxidants, voltage stabilizers, processing aids, and nucleating agents.

11. The thermoplastic acrylic resin composition according to claim 10, characterized in that, Based on the total weight of the thermoplastic acrylic resin composition (100%), the content of antioxidant is 0.01-1 wt%, the content of voltage stabilizer is 0.01-5 wt%, and the content of nucleating agent is 0.01 to 5 wt%.

12. A method for preparing the thermoplastic acrylic resin composition according to any one of claims 1-11, characterized in that, The preparation method includes: A propylene multiphase copolymer and a styrene elastomer are mixed evenly, and then the evenly mixed material is placed into a twin-screw extruder for extrusion to obtain the thermoplastic propylene-based resin composition.

13. The preparation method according to claim 12, characterized in that, The screw temperature of the twin-screw extruder is set to 180-230℃, and the feed screw speed is 50-200 r / min.

14. A shielding material, characterized in that, The shielding material comprises the thermoplastic propylene-based resin composition according to any one of claims 1-13.

15. A cable comprising at least one cable core, the cable core comprising a conductor and an inner semiconductor shielding layer, an insulating layer, and an outer semiconductor shielding layer sequentially covering the conductor, characterized in that, The insulating layer is made of the shielding material as described in claim 14, and the inner semiconductor shielding layer and / or the outer semiconductor shielding layer are made of the thermoplastic propylene-based resin composition as described in any one of claims 1-13.

16. The cable according to claim 15, characterized in that, The cable is a submarine cable.

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