Thermoplastic nanocomposite insulating material, manufacturing method therefor, and power cable comprising same

Abstract

The present invention relates to a thermoplastic nanocomposite insulating material, a manufacturing method therefor, and a power cable comprising same. More specifically, a thermoplastic nanocomposite insulating material is disclosed comprising: 95-99.99 wt% of a polyolefin-based thermoplastic elastomer resin; and 0.01-5 wt% of a silica nanoparticle powder surface-modified with two or more functional groups selected from a methyl group, an ethyl group, a phenyl group, a vinyl group, an amine group, a thiol group, and a fluorine group, wherein as for the surface-modified silica nanoparticle powder, water and a catalyst are added to a solvent containing an alkoxysilane, followed by a sol-gel reaction, thereby synthesizing a silica nanoparticle dispersion, and then silica nanoparticles are surface-modified by a reaction with an alkoxy silane having two or more functional groups selected from a methyl group, an ethyl group, a phenyl group, a vinyl group, an amine group, a thiol group, and a fluorine group, so the silica nanoparticles surface-modified with the functional groups are dispersed in the thermoplastic elastomer resin to provide insulating performance at a high temperature.

Description

Thermoplastic nanocomposite insulating material, method for manufacturing the same, and power cable comprising the same

[0001] The present invention relates to a thermoplastic nanocomposite insulating material, a method for producing the same, and a power cable including the same.

[0002] Thermoplastic polymers are polymer materials that can be reformed by heat. They are widely used across industries due to their excellent formability and easy processing, and they have the advantage of being recyclable, which allows them to be reformed by heat. Polyolefins, which are polymerized from alkene monomers and contain alkyl groups, such as polyethylene (PE) and polypropylene (PP), are representative examples. In particular, PE and PP are very inexpensive among industrial polymer materials and have excellent properties such as mechanical properties and chemical resistance, so they are widely used in various fields such as packaging materials, films, containers, pipes, and the electrical and electronic industries.

[0003] For example, in the case of power cables, crosslinked polyethylene (XLPE), obtained by crosslinking low-density polyethylene, is widely used, and recently, technology development to utilize PP-based materials is being actively conducted. This is because PP-based materials have a higher melting temperature than crosslinked polyethylene, which not only meets the need for increased heat resistance due to the trend of increasing power capacity, but also significantly reduce the burden on the process because there is no crosslinking or crosslinking byproduct removal process. In addition, while conventional XLPE is difficult to re-form due to its thermosetting nature, PP can secure environmental friendliness through recyclability.

[0004] However, PP itself has a high stiffness, that is, a high modulus of elasticity, making it unsuitable as an insulation material for cables that require flexibility. Therefore, to improve flexibility and thus impact strength, methods are being used to chemically synthesize polypropylene copolymers (PPC) or to produce blended materials through mechanical mixing with flexible materials. Active research is being conducted on the application of thermoplastic elastomers (TPEs), which have both thermoplastic and rubber-like flexibility, as cable insulation materials. TPEs produced through mechanical mixing are obtained through blending at temperatures above their melting points, and polyolefin elastomers (POEs) are the most widely used materials for melt blending with PP. POE refers to a material with rubber-like flexibility and elasticity, which is formed by copolymerization between ethylene (2 carbon atoms) and monomers with a high carbon number, such as ethylene-butene copolymer and ethylene-octene copolymer.

[0005] This is disclosed in Patent Document 1, 'Insulator for power cable (Korean Patent Registration No. 10-2174435)', which provides a method for producing a thermoplastic elastomer by blending a polyolefin elastomer with polypropylene or a polypropylene copolymer, and Patent Document 2, 'Ternary composition for cable insulation layer, method for producing same, and cable insulation layer and power cable comprising the same (Korean Patent Publication No. 10-2021-0052962)', which provides a ternary composition of polypropylene, polyolefin elastomer, and ethylene-propylene copolymer.

[0006] These TPE materials have the advantage of securing appropriate mechanical properties for use as cable insulation materials while reducing the stiffness of PP. However, problems such as low insulation properties of the flexible material itself mixed with PP, such as POE, and interface defects with PP may cause problems with insulation performance deterioration. In particular, in high-voltage cables such as HVDC and HVAC, insulation performance may be weakened due to heat generated within the insulation.

[0007] In this regard, research is being conducted on the development of nanocomposite insulating materials that can improve insulation performance by adding inorganic nanoparticles such as MgO, TiO2, and ZnO. However, there is still a need for material development that can minimize the degradation of insulation performance at high temperatures. Furthermore, even when using inorganic nanoparticles at a content of approximately 1 wt%, which is typically applied, the application of inexpensive inorganic materials such as silica (SiO2) is required for mass production in cable manufacturing, and thus there is a need for technology development that can minimize this content.

[0008] Accordingly, the inventors of the present invention completed the present invention by developing a thermoplastic nanocomposite insulating material that has excellent insulating performance, especially insulating performance at high temperatures, while securing price competitiveness through research on the surface treatment of inorganic nanoparticles in a thermoplastic elastomer nanocomposite material for high-voltage cable application.

[0009] Therefore, the present invention has as its technical solution the task of providing a thermoplastic nanocomposite insulating material.

[0010] In addition, the present invention provides a method for manufacturing the thermoplastic nanocomposite insulating material as another technical solution.

[0011] In addition, the present invention provides a power cable including the thermoplastic nanocomposite insulating material as another technical solution.

[0012] In order to solve the above technical problem, the present invention,

[0013] 95 to 99.99 wt% of polyolefin thermoplastic elastomer resin,

[0014] Consists of 0.01 to 5 wt% of silica nanoparticle powder surface-modified with two or more functional groups selected from methyl, ethyl, phenyl, vinyl, amine, thiol, and fluorine groups,

[0015] The above surface-modified silica nanoparticle powder is surface-modified by adding water and a catalyst to a solvent containing an alkoxy silane, synthesizing a silica nanoparticle dispersion through a sol-gel reaction, and then reacting the silica nanoparticle dispersion with an alkoxy silane having two or more functional groups selected from a methyl group, an ethyl group, a phenyl group, a vinyl group, an amine group, a thiol group, and a fluorine group.

[0016] A thermoplastic nanocomposite insulating material is provided, characterized in that silica nanoparticles surface-modified with the above functional group are dispersed within the thermoplastic elastomer resin and have insulating performance at high temperatures.

[0017] In the present invention, the silica nanoparticle powder surface-modified with two or more functional groups is characterized in that the surface is modified with one or more functional groups selected from a methyl group, an ethyl group, a phenyl group, and a vinyl group, and one or more functional groups selected from an amine group, a thiol group, and a fluorine group.

[0018] In addition, in the present invention, the insulating material has an insulation resistance of at least 1×10 at 110°C. 15 It is characterized by Ω·cm.

[0019] In addition, in the present invention, the thermoplastic elastomer resin is characterized by including a polypropylene resin, a polyolefin-based thermoplastic elastomer, and a dispersion modifier.

[0020] In addition, in order to solve the above other technical problems, the present invention,

[0021] A step of adding water and a catalyst to a solvent containing an alkoxy silane and synthesizing a silica nanoparticle dispersion through a sol-gel reaction;

[0022] A step of reacting the above silica nanoparticle dispersion with an alkoxy silane having a functional group for surface modification to produce a silica nanoparticle powder surface-modified with the functional group; and

[0023] A step of manufacturing a thermoplastic nanocomposite material by melt-mixing the surface-modified silica nanoparticle powder and a polyolefin-based thermoplastic elastomer resin; comprising;

[0024] The functional group for surface modification is at least two selected from a methyl group, an ethyl group, a phenyl group, a vinyl group, an amine group, a thiol group, and a fluorine group.

[0025] The above thermoplastic nanocomposite material provides a method for manufacturing a thermoplastic nanocomposite insulating material, characterized in that the silica nanoparticles are dispersed into the thermoplastic elastomer resin by the surface modification functional group, thereby having insulating performance at high temperatures.

[0026] In the present invention, the step of manufacturing the surface-modified silica nanoparticle powder is characterized by including a step of manufacturing a primary surface-modified silica nanoparticle powder by adding an alkoxy silane having the surface-modifying functional group to the silica nanoparticle dispersion, performing surface modification, and then removing the solvent; and a step of manufacturing a secondary surface-modified silica nanoparticle powder by adding an alkoxy silane having the surface-modifying functional group and a solvent together to the primary surface-modified silica nanoparticle powder.

[0027] In addition, in the present invention, it is characterized in that the surface-modified silica nanoparticle powder is mixed in an amount of 0.01 to 5.0 wt%.

[0028] In addition, in the present invention, the polyolefin-based thermoplastic elastomer resin is characterized by including a polypropylene resin, a polyolefin elastomer, and a dispersion modifier.

[0029] In addition, in order to solve the above-described further technical problem, the present invention provides a power cable including the thermoplastic nanocomposite insulating material.

[0030] The thermoplastic nanocomposite insulating material according to the present invention described above contains surface-modified silica nanoparticles, thereby improving the insulating properties of a thermoplastic elastomer composed of a polypropylene resin and a polyolefin elastomer, and has excellent insulating properties, particularly at high temperatures. In addition, the insulating material according to the present invention has excellent mechanical properties, and thus can be effectively utilized as an insulating material in various electrical and electronic fields, including power cables. Furthermore, the insulating material of the present invention can significantly reduce the burden of the process because it does not require crosslinking or crosslinking byproduct removal processes. In addition, while it is difficult to obtain re-molding properties with existing XLPE due to its thermosetting properties, the thermoplastic nanocomposite insulating material of the present invention has the effect of ensuring environmental friendliness through recyclability.

[0031] In addition, according to the method of the present invention, silica nanoparticles are manufactured by a sol-gel method, and by surface modification with two or more alkoxy silanes having functional groups through a two-step surface treatment process, a thermoplastic nanocomposite insulating material having the property of uniformly dispersing silica nanoparticles in a thermoplastic elastomer and excellent high-temperature insulating properties can be manufactured.

[0032] Figure 1 schematically illustrates a manufacturing process of a thermoplastic nanocomposite insulating material according to the present invention.

[0033] FIG. 2 is a surface photograph of a nanocomposite insulating material specimen manufactured using (a) silica surface-treated with an amine group and (b) silica surface-treated with a phenyl-amine group among thermoplastic nanocomposite insulating material specimens manufactured according to one embodiment of the present invention.

[0034] FIG. 3 is a cross-sectional SEM photograph of a nanocomposite insulating material specimen manufactured using (a) silica surface-treated with an amine group and (b) silica surface-treated with a phenyl-amine group among thermoplastic nanocomposite insulating material specimens manufactured according to one embodiment of the present invention.

[0035] FIG. 4 is a graph showing the insulation resistance values ​​at room temperature (25°C) and high temperature (110°C) of a thermoplastic nanocomposite insulating material manufactured according to one embodiment of the present invention.

[0036] FIG. 5 is a graph showing insulation resistance values ​​at room temperature (25°C) and high temperature (110°C) according to a test example for a 0.1 wt% silica content specimen of a thermoplastic nanocomposite insulating material manufactured according to one embodiment of the present invention.

[0037]

[0038] Hereinafter, the present invention will be described in detail.

[0039] First, the present invention is susceptible to various modifications and embodiments. Specific embodiments are illustrated and described in detail in the drawings. However, this is not intended to limit the present invention to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives within the spirit and technical scope of the present invention.

[0040] The terminology used herein is merely for the purpose of describing specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In the present invention, it should be understood that the terms "comprise" or "have" indicate the presence of a feature, number, step, reaction, component, or combination thereof described in the specification, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, reactions, components, or combinations thereof.

[0041] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and shall not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0042]

[0043] In one aspect, the present invention relates to a thermoplastic nanocomposite insulating material having improved insulation properties by introducing silica nanoparticles surface-modified with functional groups into a thermoplastic elastomer resin, comprising 95 to 99.99 wt% of a polyolefin thermoplastic elastomer resin and 0.01 to 5 wt% of silica nanoparticle powder surface-modified with two or more functional groups selected from a methyl group, an ethyl group, a phenyl group, a vinyl group, an amine group, a thiol group, and a fluorine group, wherein the surface-modified silica nanoparticle powder is prepared by adding water and a catalyst to a solvent containing an alkoxy silane, synthesizing a silica nanoparticle dispersion by a sol-gel reaction, and then introducing silica nanoparticles into a thermoplastic elastomer resin. It is characterized in that the silica nanoparticles surface-modified by reacting with an alkoxy silane having two or more functional groups are dispersed into the thermoplastic elastomer resin and have insulating performance at high temperatures.

[0044] In the present invention, the silica nanoparticle powder is formed into nanoparticles through a sol-gel reaction in a state where a precursor is dissolved in a solution, and is manufactured in the form of a silica nanoparticle dispersion with almost no aggregation, and is reacted with an alkoxy silane having the functional group as a surface modifier to evenly modify the surface of the nanoparticles with the functional group. Accordingly, the surface-modified silica nanoparticles are evenly dispersed in the thermoplastic elastomer resin by the functional group, and charge trapping is performed to improve insulation not only at room temperature but also at high temperatures.

[0045] Preferably, rather than introducing only a highly polar substance as the functional group, introducing a low-polarity or non-polar substance together can simultaneously improve dispersibility and insulation by increasing compatibility with hydrophobic polyolefin-based materials. Therefore, it is preferable that the silica nanoparticle powder surface-modified with the two or more functional groups is surface-modified with at least one functional group selected from among a methyl group, an ethyl group, a phenyl group, and a vinyl group as the low-polarity or non-polar functional group, and at least one functional group selected from among an amine group, a thiol group, and a fluorine group as the polar functional group.

[0046] In addition, preferably, the surface-modified silica nanoparticle powder is included in the thermoplastic nanocomposite insulating material in an amount of 0.01 to 5.0 wt%. If the silica nanoparticles are included in an amount of less than 0.01 wt%, the effect of adding the silica nanoparticles becomes very minimal, and if the silica nanoparticles are included in an amount of more than 5 wt%, there is a concern that agglomeration between silica nanoparticles may increase, resulting in a deterioration in physical properties.

[0047] The insulating material of the present invention can improve insulation resistance not only at room temperature but also at high temperatures due to improved dispersibility and insulation. Preferably, the insulation resistance at 110°C is at least 1×10 15 Ω·cm. According to a preferred embodiment of the present invention, even though the surface-modified silica nanoparticles are contained in a very small amount of 0.1 wt%, the surface-modified silica nanoparticles have a particle size of 6.27×10 15 It exhibited insulation resistance of Ω·cm.

[0048] In the insulating material of the present invention, the insulation resistance at room temperature (25°C) is at least 1×10 18 Ω·cm. According to a preferred embodiment of the present invention, even though the surface-modified silica nanoparticles are contained in a very small amount of 0.1 wt%, 5.00×10 18 It exhibited insulation resistance of Ω·cm.

[0049] In addition, in the present invention, the polyolefin-based thermoplastic elastomer resin may include a polypropylene resin, a polyolefin-based thermoplastic elastomer, and a dispersion modifier. Preferably, the polyolefin-based thermoplastic elastomer resin includes 40 to 60 parts by weight of a polypropylene resin, 40 to 60 parts by weight of a polyolefin elastomer dispersed in the polypropylene resin, and 1 to 20 parts by weight of a dispersion modifier compatible with the polypropylene resin and the polyolefin elastomer, and the dispersion modifier is characterized by satisfying the following relationship 1.

[0050] [Relationship 1]

[0051] E2 < E1 < E3

[0052] However, E1 is the elastic modulus of the dispersion modifier, E2 is the elastic modulus of the polyolefin elastomer, and E3 is the elastic modulus of the polypropylene resin.

[0053] If the polypropylene resin is added in amounts less than 40 parts by weight, the insulating layer will easily peel off due to external impact even if it is coated with an insulating layer on the conductor, making it unsuitable as an insulating material for the insulating layer surrounding the conductor. Conversely, if the polypropylene resin is added in amounts exceeding 60 parts by weight, the insulating material will not be able to provide flexibility, resulting in poor impact resistance even when completely coated with an insulating layer. Therefore, it is preferable to include 40 to 60 parts by weight of polypropylene resin to form a matrix.

[0054] The above polypropylene resin is characterized by being isotactic homo polypropylene (iPP), syndiotactic homo polypropylene (sPP), and a polypropylene copolymer (lypropylene copolymer (PPC)) derived therefrom.

[0055] The above polypropylene copolymer may be at least one of a propylene random copolymer, a propylene block copolymer, and a reactor-made thermoplastic olefin (RTPO).

[0056] In the present invention, the polyolefin elastomer is derived from a polyolefin structure and has rubber properties, can form a dispersed phase in a matrix of a polypropylene resin, and is characterized in that it is manufactured by copolymerizing ethylene and an alpha olefin (α-olefin) having 4 to 20 carbon atoms.

[0057] The polyolefin elastomer may be at least one of an ethylene-butene copolymer, an ethylene-octene copolymer, an ethylene propylene rubber (EPR), an ethylene propylene diene monomer (EPDM), a styrene-ethylene-styrene copolymer (SBS), and a styrene-ethylene-butadiene-styrene copolymer (SEBS).

[0058] In the case of polyolefin elastomers, they can have properties such as an elastic modulus of 1 to less than 100 MPa and a maximum strain of 500 to 1,500%. This is to complement the brittleness of polypropylene resin and provide flexibility. If the elastic modulus of the polyolefin elastomer is less than 1 MPa, the elastic modulus is too low to bring about a significant effect, and if it is 100 MPa or more, it has a value similar to the elastic modulus of the dispersion modifier, which has the disadvantage of being meaningless in complementing the brittleness of the polypropylene resin. If the maximum strain of the polyolefin elastomer is less than 500% or more than 1,500%, there is a problem that the elastic modulus of the polyolefin elastomer cannot be controlled in the range of 1 to less than 100 MPa.

[0059] In this way, the polyolefin elastomer having an elastic modulus of 1 to 100 MPa and a maximum strain of 500 to 1,500% can be included in an amount of 40 to 60 parts by weight. If the polyolefin elastomer is less than 40 parts by weight, even if the polyolefin elastomer is dispersed on a matrix made of a polypropylene resin, there are disadvantages of a high elastic modulus and insufficient flexibility. If it exceeds 60 parts by weight, the polyolefin elastomer having relatively low heat resistance does not form an elastic core but becomes a continuous phase and is exposed to the outer surface, or the polyolefin elastomers clump or aggregate on the polypropylene resin matrix depending on the environment, making it impossible to obtain the desired impact resistance performance. This causes a deterioration in mechanical strength or insulation performance, and therefore is not desirable for use as an insulating material.

[0060] In particular, in order to prevent destruction due to bending in consideration of the bending of the cable in order to be used as an insulating material, a low elastic modulus of less than 300 MPa is required. However, since the polypropylene resin is included in an amount of 40 to 60 parts by weight and the polyolefin elastomer dispersed in the polypropylene resin is included in an amount of 40 to 60 parts by weight, the elastic modulus of the thermoplastic nanocomposite material can be adjusted to less than 300 MPa. Accordingly, since the polyolefin elastomer can maintain the structure of an elastic core within the polypropylene resin matrix, excellent thermal, mechanical, and electrical insulation properties can be maintained.

[0061] In the present invention, the dispersion modifier includes a functional group of a propylene group contained in a polypropylene resin, an ethylene group forming a polyolefin elastomer, and an olefin group having 4 to 20 carbon atoms, thereby being compatible with the polypropylene resin and the polyolefin elastomer.

[0062] The above dispersion modifier may be a propylene-based copolymer such as an ethylene-propylene random copolymer and an ethylene-propylene block copolymer containing ethylene in a polypropylene structure, or a butylene-propylene random copolymer and a butylene-propylene block copolymer containing butylene in a polypropylene structure.

[0063] When melt blending polypropylene and polyolefin elastomers, a matrix-dispersed phase structure is generally formed due to phase separation between the two materials. However, by using the dispersion modifier, a thermoplastic elastomer having a finer and more uniform dispersed phase can be obtained.

[0064] The elastic modulus of the dispersion modifier may be higher than the elastic modulus of the polyolefin elastomer and lower than the elastic modulus of the polypropylene resin, as shown in Equation 1, and may range from 100 to 1,000 MPa.

[0065] If the elastic modulus is less than 100 MPa, it may be effective in compensating for the brittleness of polypropylene resin because it becomes similar to the elastic modulus of polyolefin elastomers, but as a result, the content of flexible materials increases further, which causes a decrease in mechanical strength, insulating strength, and physical properties at high temperatures. On the other hand, if the elastic modulus of the dispersion modifier exceeds 1,000 MPa, it becomes close to the elastic modulus range of propylene resin, making it difficult to complement the brittleness of polypropylene resin.

[0066] In this way, since the elastic modulus of the dispersion modifier compatible with polypropylene resin and polyolefin elastomer is in the range of 100 to 1,000 MPa, which is higher than that of the polyolefin elastomer and lower than that of the polypropylene resin, flexibility can be supplemented without further increasing the content of the flexible polyolefin elastomer, and a thermoplastic nanocomposite material having excellent impact resistance from room temperature (25 ℃) to low temperature (-40 ℃) as well as excellent mechanical strength, insulation strength, and high-temperature properties can be obtained.

[0067] The dispersion modifier can be added in a range of 1 to 20 parts by weight. If it is mixed in an amount less than 1 part by weight, it is an insufficient amount to improve the impact resistance of the polypropylene thermoplastic elastomer. If it exceeds 20 parts by weight, it exists not only at the interface between the matrix (polypropylene resin) and the dispersed phase (polyolefin elastomer) but also in the bulk phase inside and outside the interface, making it difficult to obtain a synergistic improvement in impact resistance due to the interface reinforcing effect.

[0068]

[0069] In another aspect, the present invention relates to a method for producing a thermoplastic nanocomposite insulating material, comprising the steps of: adding water and a catalyst to a solvent containing an alkoxy silane, and synthesizing a silica nanoparticle dispersion through a sol-gel reaction (S1); reacting the silica nanoparticle dispersion with an alkoxy silane having a functional group for surface modification to produce a silica nanoparticle powder surface-modified with the functional group (S2); And a step (S3) of manufacturing a thermoplastic nanocomposite material by melt-mixing the surface-modified silica nanoparticle powder and a polyolefin-based thermoplastic elastomer resin; wherein the functional group for surface modification is at least two selected from a methyl group, an ethyl group, a phenyl group, a vinyl group, an amine group, a thiol group, and a fluorine group, and the thermoplastic nanocomposite material is characterized in that the silica nanoparticles are dispersed into the thermoplastic elastomer resin by the functional group for surface modification, thereby having an insulating performance at high temperatures.

[0070] Figure 1 schematically illustrates the manufacturing process of the present invention. A silica nanoparticle dispersion is prepared by a sol-gel reaction, a surface-modified silica nanoparticle powder is prepared by reacting with a surface modifier, and then the silica nanoparticle powder is melt-mixed with a polyolefin thermoplastic elastomer resin to produce the thermoplastic nanocomposite insulating material.

[0071] The following steps are explained in detail.

[0072] First, a silica nanoparticle dispersion is synthesized by a sol-gel reaction (S1).

[0073] The above silica nanoparticle dispersion is characterized by being synthesized in the form of silica sol through a sol-gel reaction by adding water and a catalyst to a solvent containing a precursor, tetravalent alkoxy silane.

[0074] Here, the tetravalent alkoxy silane is a silane having four OH (hydroxyl groups), and is preferably one selected from the group consisting of tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraisopropoxysilane, tetrabutoxysilane, tetraphenoxysilane, and tetraacethoxysilane, and the group consisting of mixtures thereof.

[0075] It is preferable to use an alcohol-based solvent as the solvent, and it is preferable that it is one selected from the group consisting of methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, tert-butyl alcohol, pentyl alcohol, benzyl alcohol, and the group consisting of mixtures thereof.

[0076] The above catalyst uses a basic catalyst, and is preferably one selected from the group consisting of ammonium hydroxide, ammonium chloride, methyl amine, ethyl amine, propyl amine, isopropyl amine, butyl amine, cyclohexyl amine, dimethyl amine, diethyl amine, trimethyl amine, triethyl amine, and the group consisting of mixtures thereof.

[0077] It is preferable to use the above catalyst in an amount of 1 to 10 parts by weight per 100 parts by weight of the precursor.

[0078] The above catalyst is related to not only the reaction speed but also the size of the formed silica particles. The higher the catalyst content, the larger the silica particle size. The appropriate catalyst content varies depending on conditions such as the reaction temperature, reactant concentration, and catalyst type. However, in general, if the above catalyst is used in an amount of 10 parts by weight or more, there is a concern that the silica particle size may become excessively large, such as several hundred nm or more, and if the catalyst content is less than 1 part by weight, the reaction speed may become too slow, the reaction time may become excessively long, and the reaction may not be completed.

[0079] It is preferable to use distilled water as the water, and it is preferable to use 3 parts by weight or more per 100 parts by weight of the solvent.

[0080] The above silica nanoparticles are formed through hydrolysis and condensation reactions of the precursor tetravalent alkoxy silane. The appropriate amount of water varies depending on the reaction temperature, reactant concentration, catalyst type and content, etc., but in general, when water is less than 3 parts by weight, the hydrolysis of the precursor tetravalent alkoxy silane becomes excessively slow, which may prolong the reaction time and lead to incomplete reaction.

[0081] The temperature of the sol-gel reaction for producing the above silica nanoparticle dispersion is preferably 20 to 100°C. If the reaction temperature is lower than 20°C, a long reaction time is required for silica formation, and if the reaction temperature exceeds 100°C, evaporation may occur depending on the alcohol solvent.

[0082]

[0083] Next, surface-modified silica nanoparticle powder is manufactured (S2).

[0084] In the present invention, the surface-modified silica nanoparticle powder is characterized in that two or more alkoxy silanes having a surface-modifying functional group are added to the silica nanoparticle dispersion to perform surface treatment through a sol-gel reaction on the surface of the silica nanoparticles.

[0085] As described above, the functional group for surface modification may be two or more selected from a methyl group, an ethyl group, a phenyl group, a vinyl group, an amine group, a thiol group, and a fluorine group. Preferably, in order to improve dispersibility in a thermoplastic resin due to low polarity, at least one alkoxy silane having at least one functional group selected from a methyl group, an ethyl group, a phenyl group, and a vinyl group is included, and at least one alkoxy silane having a thiol group, an amine group, and a fluorine group that has high polarity and is effective in charge trapping is included.

[0086] That is, in relation to surface modification of inorganic particles, in order to increase the insulation, a substance with a high polarity is often introduced, which is known to be an effect due to appropriate charge trapping. However, since such substances with a high polarity tend to have high surface energy and high hydrophilicity, they have low compatibility with polyolefin-based substances with low surface energy and hydrophobicity, which may lead to a problem of low dispersibility when mixed. Therefore, in order to effectively obtain the insulation property of the polar surface-modified silane, it is recommended to use it together with a low-polarity surface-modified silane, and preferably, by using silica nanoparticle powder in which the surface of the silica nanoparticle is simultaneously treated with the two types of surface-modified silanes, dispersibility and insulation can be secured at the same time.

[0087] At this time, it is preferable that the alkoxy silane having a methyl group is at least one selected from the group consisting of methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylmethoxysilane, trimethylethoxysilane, etc. That is, it is preferable that it is selected from the group consisting of monovalent to trivalent silanes having a methyl group and the group of mixtures thereof.

[0088] In addition, it is preferable that the alkoxy silane having an ethyl group is at least one selected from the group consisting of ethyltrimethoxysilane, ethyltriethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, triethylmethoxysilane, triethylethoxysilane, etc. That is, it is preferable that it is selected from the group consisting of monovalent to trivalent alkoxy silanes having an ethyl group and the group consisting of mixtures thereof.

[0089] In addition, it is preferable that the alkoxy silane having a vinyl group is at least one selected from the group consisting of vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, and allyltriethoxysilane. That is, it is preferable that it is selected from the group consisting of monovalent to trivalent alkoxy silanes having a vinyl group and the group consisting of mixtures thereof.

[0090] In addition, it is preferable that the alkoxy silane having a phenyl group is at least one selected from the group consisting of phenyltrimethoxysilane, phenyltriethoxysilane, trimethoxysilyl naphthalene, etc. That is, it is preferable to select from the group consisting of monovalent to trivalent alkoxy silanes having a phenyl group and the group of mixtures thereof.

[0091] In addition, it is preferable that the alkoxy silane having the thiol group is at least one selected from the group consisting of mercaptopropyltrimethoxysilane ((3-Mercaptopropyl)trimethoxysilane), mercaptopropyltriethoxysilane ((3-Mercaptopropyl)triethoxysilane), mercaptopropyldimethoxymethylsilane (3-Mercaptopropyl(dimethoxy)methylsilane), etc. That is, it is preferable that it is selected from the group consisting of monovalent to trivalent alkoxy silanes having a thiol group and the group of mixtures thereof.

[0092] In addition, it is preferable that the alkoxy silane having an amine group is at least one selected from the group consisting of 3-Aminotrimethoxysilane, 3-Aminotriethoxysilane, 3-Aminopropyldimethoxymethylsilane, 3-(2-Aminoethylamino)propyldimethoxymethylsilane, etc. That is, it is preferable that it is selected from the group consisting of monovalent to trivalent alkoxy silanes having an amine group and the group of mixtures thereof.

[0093] The alkoxy silane having a fluorine group is preferably at least one selected from the group consisting of triethoxyfluorosilane, trimethoxy(3,3,3-trifluoropropyl)silane, trimethoxy(pentafluorophenyl)silane, triethoxy(pentafluorophenyl)silane, pentafluorophenylethoxydimethylsilane, dimethoxy (methyl)(3,3,3-trifluoropropyl)silane, trimethoxy (1H,1H,2H,2H-heptadecafluorodecyl) silane, triethoxy (1H,1H,2H,2H-nonafluorohexyl) silane, and triethoxy-1H,1H,2H,2H-tridecafluoro-n-octylsilane. That is, it is preferably selected from the group consisting of monovalent to trivalent alkoxy silanes having a fluorine group and the group consisting of mixtures thereof.

[0094] In addition, the step of manufacturing a surface-modified silica nanoparticle powder in the present invention is characterized by including a step of manufacturing a primary surface-modified silica nanoparticle powder by adding an alkoxy silane having a functional group for surface modification to the silica nanoparticle dispersion, performing surface modification, and then removing a solvent; and a step of manufacturing a secondary surface-modified silica nanoparticle powder by adding an alkoxy silane having a functional group for surface modification and a solvent together to the primary surface-modified silica nanoparticle powder.

[0095] In the first step, a certain amount of a surface treatment material is added to a silica sol solution, and then the solvent is removed to obtain silica nanoparticle powder. In the second step, the powder is redispersed in a solvent, and then the remaining surface treatment material is added and reacted, followed by a washing and drying process to obtain the final surface-modified silica nanoparticle powder.

[0096] In the first surface treatment step, some of the surface-modifying alkoxy silane is added to a silica nanoparticle dispersion, and a surface reaction occurs within the solution. Thereafter, the solvent is removed to produce a powder. In the first surface treatment, the surface-modifying alkoxy silane is preferably added in an amount of 1 to 10 parts by weight of the precursor.

[0097] In the above-mentioned second surface treatment step, the first surface-modified silica nanoparticle powder is redispersed in a solvent, and then the remaining surface-modifying alkoxy silane is added to allow a surface reaction to occur, and then washed and dried to manufacture a powder form. In the second surface treatment, the surface-modifying alkoxy silane is preferably added in an amount of 1 to 10 parts by weight of the precursor, and thus, through the first and second surface treatment processes, it is preferable that the final surface-modifying alkoxy silane for surface treatment be 3 to 20 parts by weight of the precursor.

[0098] In general, when surface-treating solid powder-type inorganic nanoparticles, the inorganic nanoparticle powder is redispersed in a solution and then a surface modifier is added. However, during this process, the nanoparticle powder is very difficult to properly disperse in a solvent due to agglomeration caused by physical and chemical bonds between nanoparticles due to the hydroxyl groups on the particle surface. In this case, if the surface modification reaction occurs in the form of clumped, aggregated particles, it is difficult to form the surface modifier evenly on the surface of the nanoparticles. On the other hand, the silica nanoparticles synthesized in the present invention are formed into nanoparticles through a sol-gel reaction while the precursor is dissolved in the solution, so they are manufactured in the form of a silica nanoparticle dispersion with almost no agglomeration. In this way, by adding the surface modifier while the silica nanoparticles are well dispersed in the solution, the surface modifier can be evenly bound to the surface of the nanoparticles.

[0099] Meanwhile, even in the case of a surface modification reaction in a solution such as this, if the content of the alkoxy silane for surface modification added for surface modification exceeds a certain amount, agglomeration or lumping may occur due to a sol-gel reaction between the alkoxy silane for surface modification in the solution separately from the silica nanoparticles, which may reduce the surface modification efficiency. Therefore, this problem can be solved by reducing the content of the alkoxy silane for surface modification as much as possible, and it is preferable to use it in an amount of 10 parts by weight or less compared to the precursor. On the other hand, if it is used in an amount of 1 part by weight or less compared to the precursor, the surface modification effect is minimal, making it difficult to secure dispersibility in the polymer in the future.

[0100] Meanwhile, the content of the primary surface-modifying alkoxysilane used to resolve the problem of self-bonding of the surface-modifying silane within the solution may ultimately be insufficient to secure dispersibility within the polymer and achieve the desired functionality. In this case, the secondary surface-modifying step, as described in the present invention, can be used to resolve the issue.

[0101] In this case, since the silica powder has already undergone primary surface treatment, particle aggregation due to the hydroxyl groups on the silica nanoparticle surface can be significantly reduced. Therefore, the secondary surface treatment process can achieve more complete surface modification of the silica nanoparticles.

[0102] In the above silica nanoparticle surface treatment process, the solvent can be removed by applying temperature and vacuum, and the particle powder can then be washed using a centrifuge or the like to remove reaction byproducts and foreign substances.

[0103] The manufactured silica nanoparticles are preferably 1 to 100 nm in diameter. If the particle size is less than 1 nm, the inherent inorganic properties of silica may not be fully realized. If the particle size exceeds 100 nm, the nanoscale effect, i.e., the increased surface and interfacial area, will likely not be expected to enhance physical properties.

[0104] Finally, the surface-modified silica nanoparticle powder and polyolefin thermoplastic elastomer resin are melt-mixed to produce a thermoplastic nanocomposite material (S3).

[0105] The above polyolefin-based thermoplastic elastomer resin may include a polypropylene resin, a polyolefin elastomer, and a dispersion modifier, and melt mixing is performed by adding surface-modified silica nanoparticle powder to the polypropylene resin, the polyolefin elastomer, and the dispersion modifier together and melt mixing at 150 to 250°C to produce a thermoplastic nanocomposite material including silica nanoparticles.

[0106] The above thermoplastic nanocomposite material may include 95 to 99.99 wt% of a polyolefin-based thermoplastic elastomer resin and 0.01 to 5 wt% of the surface-modified silica nanoparticle powder. In this case, if the silica nanoparticles are included in an amount of less than 0.01 wt%, the effect of adding the nanoparticles becomes very minimal, and if they are added in an amount exceeding 5 wt%, there is a concern that agglomeration between silica nanoparticles may increase, resulting in a deterioration in physical properties.

[0107] In addition, the polyolefin-based thermoplastic elastomer resin of the present invention may include a polypropylene resin, a polyolefin elastomer, and a dispersion modifier. Since this has been described above, a detailed description thereof will be omitted.

[0108] In addition, in the above S3 step, in the case of melt mixing, various methods can be applied as long as they are applied to the process of molding thermoplastic polymers, such as internal mixer, extrusion, and injection molding. Melt mixing is usually determined by the melting point of the thermoplastic resin, but can be performed in a preheated state in the range of 150 to 250 ℃. If the temperature is lower than 150 ℃ during melt mixing, not only is it difficult to completely melt the polypropylene resin, but it also takes a long time for the polyolefin elastomer to be uniformly dispersed in the matrix of the polypropylene resin, which makes the process inefficient. On the other hand, if the temperature exceeds 250 ℃ during melt mixing, the problem of deterioration of each material may occur, and in particular, it may cause deformation of the physical properties of the polyolefin elastomer, which may make it difficult to form a dispersed phase. Therefore, it is preferable to perform the process at 250 ℃ or lower in consideration of the thermal stability of the polyolefin elastomer.

[0109] As described above, according to the method of the present invention, silica nanoparticles are manufactured by a sol-gel method, and by surface modification with two or more alkoxy silanes having functional groups through a two-step surface treatment process, a thermoplastic nanocomposite insulating material having the property of uniformly dispersing silica nanoparticles in a thermoplastic elastomer and excellent high-temperature insulating properties can be manufactured.

[0110] In particular, the thermoplastic nanocomposite insulating material according to the present invention can obtain an excellent effect of insulating properties, especially at high temperatures, by improving the insulating properties of a thermoplastic elastomer composed of a polypropylene resin and a polyolefin elastomer, and further has excellent mechanical properties, so that it can be utilized as an insulating material in various electrical and electronic fields, including power cables. In addition, the present invention can be utilized as an insulating material forming an insulating layer wrapping a conductor of a wire-shaped power cable, or can be utilized as an insulating material in various electrical and electronic fields.

[0111] Accordingly, in another aspect, the present invention provides a power cable comprising a thermoplastic nanocomposite insulating material.

[0112]

[0113] The present invention will be described in more detail below with reference to an embodiment. However, the following embodiment is merely an example to aid understanding of the present invention and is not intended to limit the scope of the present invention.

[0114]

[0115] <Comparative Example 1> Manufacturing of polyolefin thermoplastic elastomer

[0116] In a comparative example, a thermoplastic elastomer without silica nanoparticles was manufactured to compare its physical properties.

[0117] A thermoplastic elastomer was prepared by melt blending 44 parts by weight, 56 parts by weight, and 10 parts by weight of isotactic homopolypropylene (iPP) as a polypropylene resin, ethylene-octene copolymer (EOC) as a polyolefin elastomer, and ethylene-propylene copolymer as a dispersion modifier, respectively, by stirring at 60 rpm for 10 minutes at 200°C using an internal mixer. Thereafter, a specimen was prepared by pressing and cooling at 200°C using a hot press.

[0118] The insulation resistance of the manufactured specimens was analyzed. The insulation resistance of the specimens was measured at 25°C and 110°C according to IEC 62631-1, and the analysis was performed using the current value obtained by applying 1 kV DC voltage for 30 min to ~500 μm thick specimens placed in an oven.

[0119]

[0120] <Comparative Example 2> Manufacture of thermoplastic elastomer nanocomposite using silica nanoparticles surface-modified with one type of alkoxysilane

[0121] A silica nanoparticle dispersion was prepared by mixing 200 parts by weight of ethanol, 100 parts by weight of distilled water, and 1.5 parts by weight of ammonia water with 100 parts by weight of tetraethoxysilane (TEOS) and reacting at 60°C for approximately 10 hours until the solid content reached 7% by weight.

[0122] Afterwards, the surface was modified by separately adding 10 parts by weight of vinyltrimethoxysilane, a vinyl silane, trimethoxy(3,3,3-trifluoropropyl)silane, a fluorine silane, aminopropyltriethoxysilane, an amine silane, and phenyltriethoxysilane, a phenyl silane, to the silica nanoparticle dispersion solution, relative to TEOS.

[0123] First, 5 parts by weight of the above silane was added and reacted at 60°C for 10 hours. Afterwards, vacuum was applied to remove the solvent, thereby producing a silica nanoparticle powder with a primary surface modification.

[0124] Afterwards, 5 parts by weight of the above silane was added together with cyclohexane for a second time, and the reaction was carried out at 60°C for 10 hours with strong stirring. Afterwards, the mixture was washed three times using a centrifuge and dried in a vacuum oven to obtain the final surface-modified silica nanoparticle powder.

[0125] Thereafter, in the process of manufacturing a thermoplastic elastomer in Comparative Example 1, the surface-modified silica nanoparticles were added together to manufacture a thermoplastic elastomer nanocomposite containing silica nanoparticles.

[0126] For the manufactured specimen, insulation resistance measurement was performed using the same method as in Comparative Example 1.

[0127]

[0128] <Example 1> Manufacture of thermoplastic elastomer nanocomposites using silica nanoparticles surface-modified with two types of alkoxysilanes

[0129] The process for manufacturing silica nanoparticle powder surface-modified with two types of alkoxy silanes was carried out in the same manner as Example 1, but phenyltriethoxysilane, a phenyl silane, and aminopropyltriethoxysilane, an amine silane, were used simultaneously in a weight ratio of 10:1 as surface-modifying materials.

[0130] Afterwards, the process of manufacturing the thermoplastic elastomer nanocomposite and measuring the insulation resistance were performed in the same manner as in Example 1.

[0131] The results are shown in Figs. 2 and 3. First, Figs. 2(a) and 3(a) are photographs and SEM images of thermoplastic nanocomposites manufactured from silica nanoparticles surface-modified with one type of amine-based silane in a comparative example. Referring to these, it can be confirmed that in Figs. 2(a) and 3(a) surface-modified with an amine-based silane, a lot of agglomeration of silica nanoparticles in the thermoplastic resin is observed. On the other hand, Figs. 2(b) and 3(b) are photographs and SEM images of thermoplastic nanocomposites manufactured from silica nanoparticles surface-modified with a phenyl-based silane and two types of amine-based silanes in an example. Referring to these, it can be confirmed that when the phenyl-based silane and the amine-based silane are treated simultaneously, agglomeration is significantly reduced and the silica nanoparticles are evenly distributed.

[0132]

[0133] Insulation resistance (Ωcm), 25℃without SNPSNP 0.1wt%SNP 0.5wt%SNP 1.0wt%Comparative example 1TPE2.98×10 17 Comparative Example 2 TPE / SNP-V-1.99×10 18 2.02×10 18 TPE / SNP-F-5.76×10 17 3.01×10 18TPE / SNP-P1.02×10 18 5.12×10 18 3.64×10 18 TPE / SNP-A5.89×10 16 7.88×10 16 2.46×10 16 Example 1 TPE / SNP-PA5.00×10 18 1.35×10 18 -

[0134] Insulation resistance (Ωcm), 110℃without SNPSNP 0.1wt%SNP 0.5wt%SNP 1.0wt%Comparative example 1TPE8.53×10 14 Comparative Example 2 TPE / SNP-V-3.34×10 16 1.82×10 16 TPE / SNP-F-8.64×10 15 1.49×10 15 TPE / SNP-P1.83×10 15 1.33×10 16 1.69×10 16 TPE / SNP-A7.75×10 15 2.04×10 16 1.16×10 16 Example 1 TPE / SNP-PA6.27×10 15 2.31×10 16 -

[0135] Also, Tables 1-2 and Figs. 4-5 show the results of insulation resistance measurements at 25℃ and 110℃ of the specimens manufactured according to Comparative Examples 1 and 2. Referring to these, in the table, TPE means thermoplastic elastomer resin, SNP means silica nanoparticles, V, F, P, and A mean vinyl, fluorine, phenyl, and amine silanes, respectively, and PA means that both phenyl and amine groups are treated simultaneously. When comparing the insulation resistance values ​​at room temperature (25℃) in Table 1 and Fig. 4, it can be seen that the insulation resistance of all thermoplastic nanocomposites containing silica nanoparticles is higher than that of pure thermoplastic resins, except for the case of silica surface-treated with amine groups. This is believed to be because, as shown in Figs. 2 and 3, the aggregated silica particles act as defects when treated with amine groups. At room temperature (25°C), thermoplastic nanocomposites prepared from silica nanoparticles surface-treated with phenyl groups exhibit the best insulating properties.

[0136] The insulation resistance at high temperature (110℃) also increased significantly for nanocomposites, similar to that at room temperature. Interestingly, when surface-treated with amine groups, the room-temperature insulation resistance decreased, whereas the high-temperature insulation resistance increased significantly compared to pure thermoplastic resins despite the reduced dispersibility. It also showed a comparable or higher level compared to silica nanoparticles with other surface functional groups. In other words, although the amine groups on the surface of silica nanoparticles are disadvantageous for dispersibility, they exhibit excellent high-temperature insulation properties.

[0137] Table 2 and Figure 5 show the results of an evaluation conducted by drastically reducing the amount of amine groups to 0.1 wt% to ensure insulation properties at both room and high temperatures and price competitiveness in mass production when simultaneously treating phenyl groups, which have good dispersibility and excellent insulation resistance, with amine groups. Referring to this, when an amine group is used alone, the insulation resistance at room temperature tends to decrease compared to a pure thermoplastic resin even at a low amount of 0.1 wt%, and the insulation resistance at high temperatures tends to increase. On the other hand, when a phenyl group is used alone, the room temperature insulation resistance increases somewhat, but the high temperature insulation resistance is somewhat lower than that of the amine group alone. In contrast, in the case of silica nanoparticles simultaneously treated with two types of surface functional groups, phenyl and amine groups, the high temperature insulation resistance is as excellent as that of an amine silane alone at a very low silica content of 0.1 wt%, and the room temperature insulation resistance also increases significantly compared to a pure thermoplastic resin.

[0138] These characteristics can be effectively achieved by surface-treating silica nanoparticles with amine groups having excellent insulating properties together with phenyl groups having excellent dispersibility, as previously mentioned in FIGS. 2 and 3, so that they are well dispersed in a thermoplastic resin without aggregation.

[0139] Therefore, due to these characteristics, it is expected that the thermoplastic nanocomposite material can be actively utilized as an insulating material in various industrial fields as well as a high-voltage cable insulating material.

[0140]

[0141] The above description is merely an illustrative illustration of the technical idea of ​​the present invention, and those skilled in the art will appreciate that various modifications and variations can be made without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the technical idea of ​​the present invention, and the scope of the technical idea of ​​the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted according to the claims, and all technical ideas within a scope equivalent thereto should be interpreted as being included in the scope of the rights of the present invention.

Claims

1. 95 to 99.99 wt% of polyolefin thermoplastic elastomer resin, Consists of 0.01 to 5 wt% of silica nanoparticle powder surface-modified with two or more functional groups selected from methyl, ethyl, phenyl, vinyl, amine, thiol, and fluorine groups, The above surface-modified silica nanoparticle powder is surface-modified by adding water and a catalyst to a solvent containing an alkoxy silane, synthesizing a silica nanoparticle dispersion through a sol-gel reaction, and then reacting the silica nanoparticle dispersion with an alkoxy silane having two or more functional groups selected from a methyl group, an ethyl group, a phenyl group, a vinyl group, an amine group, a thiol group, and a fluorine group. The silica nanoparticles surface-modified with the functional group are dispersed into the thermoplastic elastomer resin, and are characterized in that they have insulating performance at high temperatures. Thermoplastic nanocomposite insulating material.

2. In paragraph 1, Silica nanoparticle powder surface-modified with two or more functional groups mentioned above, At least one functional group selected from a methyl group, an ethyl group, a phenyl group, and a vinyl group, Characterized in that the surface is modified with at least one functional group selected from among an amine group, a thiol group, and a fluorine group. Thermoplastic nanocomposite insulating material.

3. In paragraph 1, The above insulating material has an insulation resistance of at least 1×10 at 110°C. 15 A thermoplastic nanocomposite insulating material characterized by a thickness of Ω·cm.

4. In paragraph 1, A thermoplastic nanocomposite insulating material, characterized in that the thermoplastic elastomer resin comprises a polypropylene resin, a polyolefin thermoplastic elastomer, and a dispersion modifier.

5. A step of adding water and a catalyst to a solvent containing an alkoxy silane and synthesizing a silica nanoparticle dispersion through a sol-gel reaction; A step of reacting the above silica nanoparticle dispersion with an alkoxy silane having a functional group for surface modification to produce a silica nanoparticle powder surface-modified with the functional group; and A step of manufacturing a thermoplastic nanocomposite material by melt-mixing the surface-modified silica nanoparticle powder and a polyolefin-based thermoplastic elastomer resin; comprising; The functional group for surface modification is at least two selected from a methyl group, an ethyl group, a phenyl group, a vinyl group, an amine group, a thiol group, and a fluorine group. The thermoplastic nanocomposite material is characterized in that the silica nanoparticles are dispersed into the thermoplastic elastomer resin by the surface modification functional group, thereby having insulating performance at high temperatures. Method for manufacturing thermoplastic nanocomposite insulating material.

6. In paragraph 5, The step of manufacturing the above surface-modified silica nanoparticle powder is: A step of manufacturing a first surface-modified silica nanoparticle powder by adding an alkoxy silane having a surface-modifying functional group to the silica nanoparticle dispersion, modifying the surface, and then removing the solvent; and A method for producing a thermoplastic nanocomposite insulating material, characterized by comprising a step of producing a second surface-modified silica nanoparticle powder by adding an alkoxy silane having a surface-modifying functional group and a solvent to the first surface-modified silica nanoparticle powder.

7. In paragraph 5, A method for producing a thermoplastic nanocomposite insulating material, characterized in that the surface-modified silica nanoparticle powder is mixed in an amount of 0.01 to 5.0 wt%.

8. In paragraph 5, A method for producing a thermoplastic nanocomposite insulating material, characterized in that the polyolefin-based thermoplastic elastomer resin comprises a polypropylene resin, a polyolefin elastomer, and a dispersion modifier.

9. A power cable comprising a thermoplastic nanocomposite insulating material according to any one of claims 1 to 4.

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