Highly heat-resistant and flame-retardant composition for cable coating, and polymer composite resin produced from said composition

Abstract

The present invention relates to a flame-retardant polymer composite composition that can be used as a cable covering material, and more specifically, to a highly heat-resistant and flame-retardant composition for cable covering that has excellent flame retardancy and heat resistance, low hardness, excellent flexibility, oil resistance, and processability, and has particularly improved mechanical properties, through a special combination of various organic and inorganic substances, and a polymer composite resin produced from the composition.

Description

[Technical Field]

[0001] The present invention relates to a flame-retardant polymer composite composition that can be used as a cable covering material. More specifically, the present invention relates to a highly heat-resistant and flame-retardant composition for cable covering that has excellent flame retardancy and heat resistance, low hardness, excellent flexibility and processability, and particularly improved mechanical properties through a special combination of various organic and inorganic substances, and a polymer composite resin produced from the composition. [Background technology]

[0002] Insulated wires, cables, and cords used for internal and external wiring of electric / electronic devices and energy storage devices (ESS) for electric vehicles must have flame retardancy, heat resistance, and electrical and mechanical properties (e.g., tensile strength and abrasion resistance).

[0003] Standards required for wiring materials for electric / electronic devices and energy storage devices (ESS), such as flame retardancy, heat resistance, and mechanical properties (e.g., tensile strength and abrasion resistance), are specified by UL, JIS, ASTM, etc. Specifically, in the case of flame retardancy, the flame retardancy test method varies depending on the required level (applied use), etc. Therefore, it is sufficient for the wiring material to have at least the required level of flame retardancy. For example, if the wiring material passes the vertical flame test (VW-1) specified in UL1581 (Reference Standard for Electric Wires, Cables, and Flexible Cords) or the horizontal and inclined tests (Test Methods for Rubber / Plastic Insulated Wire) specified in JIS C3005, it can be said to be flame retardant.

[0004] Typically, halogen-containing base resins such as polyvinyl chloride, polychloroprene, and polychlorinated polyethylene are used as cable covering materials for electric vehicles. However, these halogen-containing base resins have drawbacks, such as difficulty in obtaining flame-retardant covering materials with a halogen content of 0.5% or less and a toxicity index of 1.5 or less, as well as poor thermal properties at high temperatures. Furthermore, stricter environmental regulations are being put in place regarding the halogen content of existing halogen-based flame retardants. Therefore, numerous cable covering materials using environmentally friendly, non-halogen flame-retardant materials to replace polyvinyl chloride composite materials have been developed.

[0005] Recently, flame-retardant compositions containing polyolefin and metal hydroxides such as magnesium hydroxide and aluminum hydroxide have been developed to replace polyvinyl chloride and halogen flame retardants. However, in order for such compositions to exhibit flame retardant properties, an excessive amount of metal hydroxide must be added, which results in problems such as reduced flexibility and mechanical properties of the wire.

[0006] Therefore, there was a need to develop an environmentally friendly flame-retardant resin composition that is environmentally friendly because it does not use halogen-based flame retardants, and that is flexible yet has excellent mechanical properties in order to meet the flame retardancy standards in accordance with UL-1581 and JIS C3005. Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, an object of the present invention is to provide a highly heat-resistant and flame-retardant polymer composite composition for cable coating, which has high elongation and heat resistance, low hardness and flexibility, excellent flame retardancy, and improved mechanical properties, especially tensile strength, which satisfies the UL3817 standard.

[0008] Another object of the present invention is to provide a flame-retardant polymer composite resin comprising the polymer composite composition for cable coating, which has high melt flow index, elongation, and heat resistance, low hardness, flexibility, and therefore excellent processability, and also has improved mechanical properties, especially tensile strength, making it suitable for use in cables for charging electric vehicles and energy storage systems (ESS), and a cable coated with the resin layer.

[0009] The objectives of the present invention are not limited to those mentioned above, and may naturally include objectives of the invention that a person with ordinary skill in the art can recognize from the detailed description of the invention described below, even if they are not explicitly mentioned. [Means for solving the problem]

[0010] To achieve the above object, the present invention provides a highly heat-resistant and flame-retardant polymer composite composition for cable coating, comprising 45% by weight to 70% by weight of a polyolefin resin composition, 20% by weight to 35% by weight of a calcium-based flame retardant, 1% by weight to 10% by weight of a non-halogen flame retardant, and 1% by weight to 10% by weight of a crosslinking aid.

[0011] In a preferred embodiment, the polyolefin resin composition contains a polar polyolefin resin and a polyolefin resin in a weight ratio of 1:9 to 7:3. In a preferred embodiment, the polar polyolefin resin has a structure in which a polar monomer is grafted onto a polyolefin resin, and the polar monomer is contained in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the total weight. In a preferred embodiment, the polar monomer is at least one selected from the group consisting of maleic anhydride, acrylic acid, glyceryl methacrylate, and combinations thereof. In a preferred embodiment, the polyolefin resin is any one selected from the group consisting of polyethylene, polypropylene, polyethylene / α-olefin, ethylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, ethylene-propylene-diene copolymer, and combinations thereof. In a preferred embodiment, the polar polyolefin resin has a weight average molecular weight of 50,000 g / mol to 500,000 g / mol, a melt flow index of 1 g / 10 min to 10 g / 10 min, and a Shore hardness (Shore D) of 60 or less.

[0012] In a preferred embodiment, the calcium-based flame retardant is any one selected from the group consisting of calcium carbonate, calcium sulfate, and combinations thereof. In a preferred embodiment, the calcium-based flame retardant has a water content of 10 parts by weight or less.

[0013] In a preferred embodiment, the non-halogen flame retardant is any one of a metal hydroxide flame retardant, a phosphorus flame retardant, and a nitrogen flame retardant.

[0014] In a preferred embodiment, the phosphorus-based flame retardant is any one selected from the group consisting of ammonium polyphosphate, pentaerythritol, red phosphorus, melamine, melamine cyanurate, melamine polyphosphate, aluminum diethylphosphinate, piperazine pyrophosphate, and combinations thereof.

[0015] In a preferred embodiment, the crosslinking coagent is any one selected from the group consisting of triaryl cyanurate, triaryl isocyanurate, trimethylolpropane trimethacrylate, and combinations thereof.

[0016] In a preferred embodiment, the composition further comprises at least one of a styrenic block copolymer, an organosilane, an antioxidant, a lubricant, and a colorant. In a preferred embodiment, the styrene-based block copolymer is any one selected from the group consisting of styrene-ethylene-butadiene-styrene copolymer, styrene-butadiene-styrene copolymer, and combinations thereof. In a preferred embodiment, the styrene-based block copolymer is contained in an amount of 1 to 15% by weight, the organosilane is contained in an amount of 0.1 to 2% by weight, the antioxidant is contained in an amount of 0.1 to 7% by weight, the lubricant is contained in an amount of 0.1 to 5% by weight, and the colorant is contained in an amount of 0.1 to 3% by weight.

[0017] In a preferred embodiment, the organosilane is any one selected from the group consisting of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltributoxysilane, propyltrimethoxysilane, propyltriethoxysilane, and combinations thereof; the antioxidant is at least one selected from the group consisting of phenolic antioxidants selected from the group consisting of pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), 2,3-bis[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionyl]propionohydrazide, 2,2'-thiodiethylbis[3-(3,5-di-tert-butyl-4-hydroxydiphenyl)propionate], and combinations thereof; phosphorus-based antioxidants including tris(2,4-di-tert-butylphenyl)phosphite; sulfur-based antioxidants including distearyl thiodipropionate; and combinations thereof; the lubricant is any one selected from the group consisting of paraffin, polyethylene wax, alkaline earth metal stearates, vinylidene fluoride-hexafluoropropylene copolymers, polyester polyols, erucamide, oleic acid amide, and combinations thereof; The colorant is any one selected from the group consisting of carbon black, titanium dioxide, pigments, and combinations thereof.

[0018] The present invention also provides a highly heat-resistant and flame-retardant polymer composite resin for cable coating, which is formed from any one of the above-mentioned highly heat-resistant and flame-retardant polymer composite compositions for cable coating. In a preferred embodiment, the high heat resistance and flame retardant polymer composite resin for cable coating has flame retardancy that meets the UL1581VW-1 standard and heat resistance at a use temperature of 125°C or higher. The present invention also provides a flame-retardant polymer composite resin for cable coating, which is formed from the above-mentioned highly heat-resistant and flame-retardant polymer composite composition for cable coating. The present invention also provides a flame-retardant cable including one or more insulating coating layers formed from the above-mentioned polymer composite resin. [Effects of the Invention]

[0019] The high heat-resistant and flame-retardant polymer composite composition for cable coating of the present invention has high elongation and heat resistance, low hardness, and hence flexibility, and has excellent extrusion processability. In addition, the mechanical properties, particularly the tensile strength, satisfy the UL3817 standard, and therefore have properties suitable for use as a coating material for electric vehicle charging cables and energy storage system (ESS) cables.

[0020] The flame-retardant polymer composite resin of the present invention and the cable coated with the resin layer thereof have flame retardancy and mechanical properties that meet not only the UL1581VW-1 standard but also the UL3817 standard.

[0021] These technical effects of the present invention are not limited to the scope mentioned above, and naturally include effects of the invention that can be recognized by a person with ordinary skill in the art from the description of specific details for implementing the invention described below, even if not explicitly mentioned. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a diagram showing types of flame retardants. DETAILED DESCRIPTION OF THE INVENTION

[0023] The terms used in the present invention are merely used to describe specific embodiments and are not intended to limit the present invention. A singular expression includes a plural expression unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" and the like are intended to specify the presence of a feature, number, step, operation, component, part, or combination thereof described in the description of the invention, and should be understood not to preclude the presence or possibility of addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0024] Terms such as "first" and "second" may be used to describe various components, but these components should not be limited by these terms. These terms are used only to distinguish one component from another. For example, a first component could be designated a second component, and similarly, a second component could be designated a first component, without departing from the scope of the present invention.

[0025] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted to have a meaning consistent with the contextual meaning of the relevant art, and should not be interpreted in an ideal or overly formal sense unless expressly defined in this invention.

[0026] When interpreting elements, it is understood that a range of error is included unless otherwise expressly stated. In particular, when terms such as "weak" and "substantially" are used, they can be understood to mean a numerical value or a value close to that numerical value when the manufacturing and material tolerances inherent in the referred meaning are presented. Furthermore, when a range of numerical values ​​is disclosed in the description, such a range is continuous and includes all values ​​from the minimum value to the maximum value, inclusive, unless otherwise specified. Furthermore, when such a range refers to integers, all integers from the minimum value to the maximum value, inclusive, are included unless otherwise specified.

[0027] When describing a temporal relationship, for example, when the temporal precedence is described using expressions such as "after," "following," "next to," or "before," this also includes cases where the relationship is not consecutive, unless "immediately" or "directly" is used.

[0028] The technical configuration of the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments.

[0029] However, the present invention is not limited to the embodiments described herein, and like reference numerals may refer to like elements in various forms.

[0030] The technical feature of the present invention is a flame-retardant polymer composite composition for cables that has excellent flame retardancy and heat resistance due to a special combination of various organic and inorganic materials, and has excellent flexibility and extrusion processability due to its low hardness. Its mechanical properties, especially its tensile strength, meet the UL3817 standard, making it suitable as a covering material for electric vehicle charging cables and charging cables for energy storage systems (ESS).

[0031] Therefore, the highly heat-resistant and flame-retardant polymer composite composition for cable coating of the present invention contains 45 to 70% by weight of a polyolefin resin composition, 20 to 35% by weight of a calcium-based flame retardant, 1 to 10% by weight of a non-halogen flame retardant, and 1 to 10% by weight of a crosslinking aid, and may further contain at least one of a styrene-based block copolymer, an organosilane, an antioxidant, a lubricant, and a colorant, as necessary.

[0032] The polyolefin resin composition is not limited as long as it is composed of a polar polyolefin resin and a polyolefin resin, but in one embodiment, the polar polyolefin resin and the polyolefin resin may be contained in a weight ratio of 1:9 to 7:3. This is because if the ratio is less than 1:9, there is a risk of a decrease in physical properties due to insufficient compatibility with additives, and if it exceeds 7:3, there is a risk of a decrease in heat resistance due to residual initiator in the polar polyolefin resin.

[0033] The polar polyolefin resin is a modified resin prepared by introducing a polar functional group into a polyolefin resin. In one embodiment, the polar polyolefin resin may have a structure in which a polar monomer is grafted onto the polyolefin resin. The polar polyolefin resin may be prepared by grafting a polar monomer containing a polar functional group onto the polyolefin resin through reactive extrusion. A reaction initiator may be added to the graft reaction to obtain the polar polyolefin resin. The reaction initiator may be an organic peroxide.

[0034] As a result, the polar polyolefin-based resin may include a polyolefin-based resin main chain, a polar monomer grafted to the main chain, and a polar functional group contained in the polar monomer. The polar monomer may be one or more selected from the group consisting of maleic anhydride, acrylic acid, glyceryl methacrylate, and combinations thereof. The polyolefin-based resin may be one or more selected from the group consisting of polyethylene, polypropylene, polyethylene / α-olefin, ethylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, ethylene-propylene-diene copolymer, and combinations thereof.

[0035] The graft amount of the polar monomer contained in the polar polyolefin resin is not particularly limited, but in one embodiment, it may be 0.1 to 5 parts by weight based on 100 parts by weight of the polar polyolefin resin. This is because if it is less than 0.1 part by weight, the effect of modifying the polyolefin resin may not be significant, and if it exceeds 5 parts by weight, defects such as reduced processability and yellowing may occur.

[0036] In one embodiment, the polar polyolefin resin contained in the highly heat-resistant and flame-retardant polymer composite composition for cable coating of the present invention may have a weight-average molecular weight of 50,000 g / mol to 500,000 g / mol, a melt flow index of 1 g / 10 min to 10 g / 10 min (230°C, 2.16 kgf), and a Shore hardness (Shore D) of 60 or less. The lower limit of the Shore hardness is not particularly limited, but may be, for example, 20 or more or 30 or more. If the physical properties of the polar polyolefin resin fall outside the above-mentioned ranges, the physical properties of the finally obtained highly heat-resistant and flame-retardant polymer composite composition for electric vehicle cable coating of the present invention, such as the melt flow index, Shore hardness (Shore D), tensile strength, and elongation, may not meet the required values.

[0037] The polyolefin resin contained in the polyolefin resin composition may be any known olefin resin, but in one embodiment, it may be any one selected from the group consisting of polyethylene, polypropylene, polyethylene / α-olefin, ethylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, ethylene-propylene-diene copolymer, and combinations thereof.

[0038] The polyolefin resin composition having these properties may be contained in the highly heat-resistant and flame-retardant polymer composite composition for cable coating of the present invention in an amount of 45 to 70 wt %. This is because if the content of the polyolefin resin composition is less than 45 wt %, the extrusion appearance and processability may be reduced due to insufficient filler loading, and if it exceeds 70 wt %, the flame retardancy of the polymer composite resin may be reduced due to insufficient flame retardant content.

[0039] The calcium-based flame retardant is a component for improving the flame retardancy of the polymer composite composition. The calcium-based flame retardant is not limited as long as it is a calcium-based compound having flame retardancy, but in one embodiment, it may be at least one selected from the group consisting of calcium carbonate, calcium sulfate, and combinations thereof.

[0040] If necessary, the calcium-based flame retardant may be surface-modified to enhance compatibility with other compounds. In one embodiment, the calcium-based flame retardant may be modified so that its surface is coated with silane or stearic acid.

[0041] The calcium-based flame retardant used in the present invention may have a water content of 10 parts by weight or less and an average particle size of 1 to 20 μm. The average particle size can be measured using a commercially available laser diffraction / scattering particle size analyzer, such as a Microtrac particle size analyzer. Alternatively, 200 particles may be randomly selected from an electron microscope photograph and the average particle size may be calculated.

[0042] The calcium-based flame retardant having such properties can be contained in the highly heat-resistant and flame-retardant polymer composite composition for cable coating of the present invention in an amount of 20 to 35 wt %. If the amount is less than 20 wt %, the flame retardancy may be reduced, and if the amount is more than 35 wt %, the extrusion processability and the quality of the extrusion appearance may be reduced.

[0043] The non-halogen flame retardant is a component that exhibits flame retardancy and may be any of the metal hydroxide-based flame retardants, phosphorus-based flame retardants, and nitrogen-based flame retardants shown in FIG. 1. The metal hydroxide-based flame retardant may include magnesium hydroxide, aluminum hydroxide, etc. The nitrogen-based flame retardant may include melamine resin, melamine cyanurate, etc. The phosphorus-based flame retardant may be one or more selected from the group consisting of ammonium polyphosphate, pentaerythritol, red phosphorus, melamine, melamine cyanurate, melamine polyphosphate, aluminum diethylphosphinate, piperazine pyrophosphate, and combinations thereof. The flame retardant may be surface-treated with a silane-based or titanate-based coupling agent, and the surface-treated flame retardant may have improved dispersibility in the polymer composite resin.

[0044] The non-halogen flame retardant having these properties can be included in the highly heat-resistant and flame-retardant polymer composite composition for cable coating of the present invention in an amount of 1 to 10 wt%, but a sufficient amount can be used to meet the UL1581VW-1 standard. If the non-halogen flame retardant content is less than 1 wt%, the flame retardancy of the flame-retardant polymer composite composition will be insufficient. If the content is more than 10 wt%, molding processability such as flexibility, elongation, and extrusion may be reduced, resulting in a poor extrusion appearance and whitening of the wire surface.

[0045] The crosslinking aid is a component for improving crosslinking properties and heat and oil resistance during the preparation of the polymer composite resin of the present invention, and any crosslinking aid that can be used for polyolefin resins may be used. In one embodiment, the crosslinking aid may be at least one selected from the group consisting of triaryl cyanurate, triaryl isocyanurate, trimethylolpropane trimethacrylate, and combinations thereof.

[0046] The crosslinking aid may be contained in the highly heat-resistant and flame-retardant polymer composite composition for cable coating of the present invention in an amount of 1 to 10 wt %. If the content of the crosslinking aid is less than 1 wt %, the crosslinking efficiency of the composition will be low, resulting in poor physical properties. If the content of the crosslinking aid is more than 10 wt %, the crosslinking aid may leach out of the resin, resulting in poor quality and possibly a decrease in elongation due to an excessive crosslinking reaction during irradiation crosslinking.

[0047] The styrene-based block copolymer is a type of rubber component and may be included as an insulating material, and may be any one selected from the group consisting of styrene-ethylene-butadiene-styrene copolymer, styrene-butadiene-styrene copolymer, and combinations thereof. In one embodiment, the styrene-ethylene-butadiene-styrene copolymer may be formed to have a styrene content of 10% by weight to 40% by weight, and in one embodiment, the styrene-butadiene-styrene copolymer may be formed to have a styrene content of 20% by weight to 50% by weight.

[0048] In addition, as an embodiment, the styrene-ethylene-butadiene-styrene copolymer may have a melt flow index of 0.1 g / 10 min to 10 g / 10 min (190°C, 2.16 kg, 10 minutes) and a Shore hardness (Shore A) of 90 or less. In an embodiment, the styrene-butadiene-styrene copolymer may have a melt flow index of 0.1 g / 10 min to 10 g / 10 min (190°C, 2.16 kg, 10 minutes) and a Shore hardness (Shore A) of 50 to 80.

[0049] The styrene-based block copolymer having these properties may be included in the highly heat-resistant and flame-retardant polymer composite composition for cable coating of the present invention in an amount of 1 to 15 wt %. This is because, if it is less than 1 wt %, the hardness becomes too high, resulting in a problem in flexibility, and if it exceeds 15 wt %, not only does it reduce the tensile strength but it also inhibits the condensation reaction of the polar polyolefin-based resin, resulting in a problem in flame retardancy.

[0050] The organosilane is a component for introducing a basic functional group into the highly heat-resistant and flame-retardant polymer composite composition for cable coating, and may be an organic compound having a silicon atom (Si) at its center and to which a hydrogen atom, a hydroxyl group (-OH), an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 2 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms and one or more double bonds is bonded.

[0051] Therefore, organic silane undergoes a condensation reaction with maleic acid in polar olefin resins, and water is produced in the process, which can result in high flame retardancy with an oxygen index of 40% or more.

[0052] In one embodiment, the organosilane is not limited as long as it contains at least one functional group selected from a hydroxy group and an alkoxy group, and may be at least one selected from the group consisting of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltributoxysilane, propyltrimethoxysilane, propyltriethoxysilane, and combinations thereof.

[0053] The organosilane having such properties may be contained in the highly heat-resistant and flame-retardant polymer composite composition for cable coating of the present invention in an amount of 0.1 to 2 wt %. This is because if the amount is less than 0.1 wt %, the flame retardancy of the flame-retardant polymer composite composition may not be improved due to a decrease in acid-base reaction, and if the amount is more than 2 wt %, the extrusion processability may be reduced due to a decrease in the melt flow index.

[0054] The antioxidant is a component for preventing oxidation and improving heat resistance, and any known antioxidant may be used. In one embodiment, the antioxidant may be selected from the group consisting of a phenol-based primary antioxidant, a phosphorus-based secondary antioxidant, a sulfur-based secondary antioxidant, and combinations thereof.

[0055] The phenol-based primary antioxidant is any one selected from the group consisting of pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), 2,3-bis[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionyl]propionohydrazide, 2,2'-thiodiethyl bis-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and combinations thereof. The phosphorus-based secondary antioxidant may include tris(2,4-di-tert-butylphenyl)phosphite, and the sulfur-based secondary antioxidant may include distearyl thiodipropionate.

[0056] The antioxidant having such properties can be contained in the highly heat-resistant and flame-retardant polymer composite composition for cable coating of the present invention in an amount of 0.1 to 7 wt %. If the amount is less than 0.1 wt %, the effect of improving the antioxidant and heat resistance cannot be expected, and if the amount is more than 7 wt %, whitening due to precipitation on the surface of the electric wire may occur.

[0057] The lubricant is a component for improving processability, and any lubricant commonly used in the art can be used. In one embodiment, the lubricant may be any one selected from the group consisting of low-molecular-weight paraffin having a weight-average molecular weight of 100 to 1,000, polyethylene wax, alkaline earth metal stearates, vinylidene fluoride-hexafluoropropylene polymers, polyester polyols, erucamide, oleic acid amide, and combinations thereof.

[0058] The lubricant having the above-described properties may be contained in the highly heat-resistant and flame-retardant polymer composite composition for cable coating of the present invention in an amount of 0.1 to 5 wt %. This is because if the amount is less than 0.1 wt %, the effect of improving processability cannot be expected, and if the amount is more than 5 wt %, the dispersion of the mixture may be reduced and poor appearance may occur due to the generation of low-molecular-weight gases.

[0059] The colorant is a component that imparts color to the high heat-resistant and flame-retardant polymer composite composition for cable coating of the present invention, and may further include a conventional colorant. In one embodiment, the colorant is selected from the group consisting of carbon black, titanium dioxide, pigments, and combinations thereof. The colorant may be included in the high heat-resistant and flame-retardant polymer composite composition for cable coating of the present invention in an amount of 0.1 to 3 wt %. This is because if the colorant is less than 0.1 wt %, the desired color cannot be achieved, and if the colorant is more than 3 wt %, problems such as reduced melt flow index, tensile strength, and elongation may occur.

[0060] Next, the polymer composite resin for cable coating of the present invention can be formed from a high heat-resistant and flame-retardant polymer composite composition for cable coating containing the above-mentioned components. Any known method for producing a resin can be used to obtain the polymer composite resin for cable coating from the high heat-resistant and flame-retardant polymer composite composition for cable coating of the present invention. In one embodiment, the polymer composite resin for cable coating can be obtained by feeding a mixed raw material containing the high heat-resistant and flame-retardant polymer composite composition for cable coating into a twin screw extruder, kneader, Banbury mixer, etc., and melt-processing the mixed raw material.

[0061] The polymer composite resin for cable coating of the present invention has high flame retardancy that meets the UL1581VW-1 standard, heat resistance at an operating temperature of 125°C or higher, and a low Shore hardness (Shore A) of 75 to 90, making it flexible, making it suitable for use as a coating for electric vehicle charging cables and energy storage system (ESS) cables.

[0062] Next, the flame-retardant cable of the present invention can be manufactured by covering a conductor with an insulating coating layer formed from the polymer composite resin having the above-described configuration. Specifically, the flame-retardant cable can be manufactured by forming an insulating coating layer on a conductor such as copper or aluminum using a polymer composite resin produced by melt-processing a highly heat-resistant and flame-retardant polymer composite composition for cable coating. One or more insulating coating layers formed from the polymer composite resin can be formed. That is, when manufacturing a low-voltage cable, only one layer can be coated using a single-layer extruder, and when manufacturing a high-voltage cable, multiple layers can be coated using a double-layer or triple-layer extruder.

[0063] As described above, the polymer composite resin of the present invention has high flame retardancy and excellent mechanical properties, and can be stably extruded for a long period of time due to minimal pressure increase in the extruder during the extrusion molding process for cable production.

[0064] Examples 1 to 12 The components shown in Table 1 below were uniformly mixed in the amounts shown to prepare highly heat-resistant and flame-retardant polymer composite compositions 1 to 12 for cable coating.

[0065] [Table 1]

[0066] The polyolefin resin composition used here consisted of polyethylene resin and polar polyethylene / α-olefin resin in a weight ratio of 7:3. The polar polyethylene / α-olefin resin was a polar ethylene-α-olefin block copolymer grafted with 0.5 wt% maleic anhydride and had a melt flow index of 0.8 g / 10 min. The styrene-based block copolymer used was a styrene-ethylene-butadiene-styrene copolymer. The styrene-ethylene-butadiene-styrene copolymer used had a melt flow index of 1 g / 10 min and a Shore hardness of 72. Calcium carbonate coated with stearic acid (particle size: 1.5 μm) was used as the calcium-based flame retardant, propyltrimethoxysilane was used as the organosilane, and aluminum diethylphosphinate, a phosphorus-based flame retardant, was used as the non-halogen-based flame retardant. Trimethylolpropane triacrylate was used as the crosslinking aid. The lubricant used was a 50% by weight masterbatch of hexafluoropropylene-vinylidene fluoride copolymer (carrier resin: polyethylene), and the antioxidants used were as follows: A: pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate), B: tris(2,4-di-tert-butylphenyl)phosphite, C: 2',3-bis[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionyl]propionohydrazide, D: distearyl thiodipropionate.

[0067] Examples 13 to 24 The highly heat-resistant and flame-retardant polymer composite compositions 1 to 12 for cable coating obtained in Examples 1 to 12 were melted and then processed to produce polymer composite resins 1 to 12. Here, the processing equipment used was a 30φ twin screw extruder (L / D 40), and the processing temperature was 100 to 230°C.

[0068] Comparative Examples 1 to 8 Comparative compositions 1 to 8 were prepared by uniformly mixing the components shown in Table 2 below in the amounts indicated.

[0069] [Table 2]

[0070] Comparative Examples 9 to 16 Comparative compositions 1 to 8 obtained in Comparative Examples 1 to 8 were treated in the same manner as in Example 13 to produce comparative composite resins 1 to 8.

[0071] Experimental Example Test pieces were prepared for polymer composite resins 1 to 12 prepared in Examples 13 to 24 and comparative resins 1 to 8 prepared in Comparative Examples 9 to 16, and the physical properties were measured as follows. The results are shown in Table 3.

[0072] 1. Evaluation of room temperature tensile strength and elongation In accordance with the IEC 60811-501 standard, the room temperature tensile strength and elongation of each test piece obtained in the examples and comparative examples were evaluated at a speed of 508 mm / min. The pass criteria were a tensile strength of 13.79 MPa or more and an elongation of 300% or more.

[0073] 2. Heat resistance evaluation According to the KS M 6518 standard, the test piece was heated at 158°C for 168 hours, and then the tensile strength and elongation were measured. Based on the UL3817 product standard, the value that was the same as the initial value was taken as 100%, and if the change rate was less than 20%, it was evaluated as passing.

[0074] 3. Flame retardancy evaluation After producing cables conforming to the UL1581VW-1 standard, the cables produced in the examples and comparative examples were stood vertically and exposed to flame for 15 seconds (repeated five times), after which the extinguishing time was evaluated based on the residual flame. If the total extinguishing time for the residual flame after five exposures to flame was within 60 seconds, the cable was rated as passing.

[0075] 4. Appearance evaluation Although there is no numerical evaluation method for appearance in the UL3817 standard, if there are no appearance defects such as surface protrusions or pores, it is evaluated as passing.

[0076] From Table 3, it can be seen that all of the polymer composite resins 1 to 12 obtained in Examples 13 to 24 exhibit flame retardancy that meets the UL1581VW-1 standard. Although not specifically shown, the Shore hardness (Shore D) is good at a level of 42 to 44, and the rate of change in the heat resistance test is within 10%, which clearly meets the pass standard of less than 20%. Not only that, the tensile strength and elongation also meet all the required values.

[0077] [Table 3]

[0078] In contrast, Comparative Resin 1 was prepared from a composition containing less than the polyolefin-based resin content and more than the calcium-based flame retardant content, and therefore failed to meet all other criteria except for flame retardancy. Comparative Resin 2, like Comparative Resin 1, was prepared from a composition containing less than the polyolefin-based resin content and more than the calcium-based flame retardant content. However, because it contained a higher polyolefin-based resin content and less calcium-based flame retardant than Comparative Resin 1, Comparative Resin 2 showed better results in tensile strength and elongation than Comparative Resin 1, but passed the flame retardancy, heat resistance, and appearance standards. Comparative Resins 3 and 4 were both prepared from compositions containing the polyolefin-based resin content within the specified range and less than the calcium-based flame retardant content. Although Comparative Resin 4 did not meet the flame retardancy standards, it passed the remaining standards. However, Comparative Resin 4 did not have as good flame retardancy as Comparative Resin 3 due to the absence of a phosphorus-based flame retardant, and it was inferior in tensile strength and elongation due to the absence of an organosilane. Comparative Resin 5 does not contain a crosslinking aid, and therefore the polyolefin resin content is within the appropriate range, but crosslinking is insufficient, resulting in unsatisfactory tensile strength and heat resistance at high temperatures. Comparative Resin 6 is made from a composition containing a calcium-based flame retardant below the appropriate content range, and its heat resistance and appearance are below the acceptable standards. Comparative Resin 7 is made from a composition containing a calcium-based flame retardant at a content higher than the optimal range, and does not meet the heat resistance standards. Comparative Resin 8 is made from a composition containing a polyolefin resin at a content lower than the optimal range, and its tensile strength does not meet the required value.

[0079] Although the present invention has been described with reference to the preferred embodiments described above, it is not limited to the above embodiments and various changes and modifications can be made by those skilled in the art to which the invention pertains without departing from the spirit of the present invention.

Claims

1. A highly heat-resistant and flame-retardant polymer composite composition for cable coating, comprising: 47% by weight to 65% by weight of a polyolefin-based resin composition containing a polyethylene resin as a polyolefin-based resin and an ethylene-α-olefin resin grafted with 0.5% by weight of maleic anhydride as a polar polyolefin-based resin, in a weight ratio of 7:3; 20% by weight to 29.5% by weight of calcium carbonate coated with stearic acid as a calcium-based flame retardant; 1% by weight to 3.5% by weight of aluminum diethylphosphinate as an organometallic phosphinate-based flame retardant; and 1% by weight to 4% by weight of trimethylolpropane triacrylate as a crosslinking aid.

2. 10. The highly heat-resistant and flame-retardant polymer composite composition for cable coating according to claim 1, wherein the polar polyolefin resin has a weight-average molecular weight of 50,000 g / mol to 500,000 g / mol, a melt flow index of 1 g / 10 min to 10 g / 10 min, and a Shore hardness (Shore D) of 60 or less.

3. 2. The highly heat-resistant and flame-retardant polymer composite composition for cable coating according to claim 1, wherein the calcium-based flame retardant has a water content of 10 parts by weight or less.

4. The highly heat-resistant and flame-retardant polymer composite composition for cable coating according to any one of claims 1 to 3, further comprising at least one of a styrene-based block copolymer, an organosilane, an antioxidant, a lubricant, and a colorant.

5. 5. The highly heat-resistant and flame-retardant polymer composite composition for cable coating according to claim 4, wherein the styrene-based block copolymer is at least one selected from the group consisting of a styrene-ethylene-butadiene-styrene copolymer, a styrene-butadiene-styrene copolymer, and a combination thereof.

6. 5. The highly heat-resistant and flame-retardant polymer composite composition for cable coating according to claim 4, wherein the styrene-based block copolymer is contained in an amount of 1 to 15 wt %, the organosilane in an amount of 0.1 to 2 wt %, the antioxidant in an amount of 0.1 to 7 wt %, the lubricant in an amount of 0.1 to 5 wt %, and the colorant in an amount of 0.1 to 3 wt %.

7. the organosilane is any one selected from the group consisting of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltributoxysilane, propyltrimethoxysilane, propyltriethoxysilane, and combinations thereof; the antioxidant is at least one selected from the group consisting of a phenolic antioxidant selected from the group consisting of pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate), 2,3-bis[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionyl]propionohydrazide, 2,2'-thiodiethylbis[3-(3,5-di-tert-butyl-4-hydroxydiphenyl)-propionate], and combinations thereof; a phosphorus-based antioxidant including tris(2,4-di-tert-butylphenyl)phosphite; a sulfur-based antioxidant including distearyl thiodipropionate; and combinations thereof; the lubricant is any one selected from the group consisting of paraffin, polyethylene wax, alkaline earth metal stearates, vinylidene fluoride-hexafluoropropylene copolymers, polyester polyols, erucamide, oleic acid amide, and combinations thereof; 5. The highly heat-resistant and flame-retardant polymer composite composition for cable coating according to claim 4, wherein the colorant is any one selected from the group consisting of carbon black, titanium dioxide, pigments, and combinations thereof.

8. A highly heat-resistant and flame-retardant polymer composite resin for cable coating, which is formed from the highly heat-resistant and flame-retardant polymer composite composition for cable coating according to any one of claims 1 to 3.

9. 9. The highly heat-resistant and flame-retardant polymer composite resin for cable coating according to claim 8, which has flame retardancy that meets the UL1581VW-1 standard and heat resistance at a usage temperature of 125°C or higher.

10. A flame-retardant polymer composite resin for cable coating, which is formed from the highly heat-resistant and flame-retardant polymer composite composition for cable coating according to claim 4.

11. A flame-retardant cable comprising one or more insulating coating layers formed from the polymer composite resin according to claim 8.

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